ORCID Profile
0000-0003-1899-005X
Current Organisation
Southern Cross University
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Geochemistry | Isotope Geochemistry | Ecosystem Function | Carbon Sequestration Science | Inorganic Geochemistry | Chemical Oceanography | Surfacewater Hydrology | Plant Physiology | Forestry Management and Environment | Land Capability and Soil Degradation | Plant Biology | Organic Geochemistry
ANZSRC Socio-Economic Objective (SEO)
Ecosystem Assessment and Management of Coastal and Estuarine Environments | Physical and Chemical Conditions of Water in Coastal and Estuarine Environments | Expanding Knowledge in the Environmental Sciences | Ecosystem Assessment and Management of Fresh, Ground and Surface Water Environments | Ecosystem Assessment and Management of Forest and Woodlands Environments | Climate Change Mitigation Strategies | Climate Variability (excl. Social Impacts) | Coastal and Estuarine Water Management |
Related Links
Publications
Mapping short-lived radium isotopes in estuarine residential canals (Gold Coast, Australia)
Publisher: Springer Science and Business Media LLC
Date: 23-06-2017
Submarine groundwater discharge and associated fluxes of alkalinity and dissolved carbon into Moreton Bay (Australia) estimated via radium isotopes
Publisher: Elsevier BV
Date: 08-2015
Net landscape carbon balance of a tropical savanna: Relative importance of fire and aquatic export in offsetting terrestrial production
Publisher: Wiley
Date: 13-08-2020
DOI: 10.1111/GCB.15287
The Role of Hydraulic Failure in a Massive Mangrove Die-Off Event
Publisher: Frontiers Media SA
Date: 27-04-2022
Abstract: Between late 2015 and early 2016, more than 7,000 ha of mangrove forest died along the coastline of the Gulf of Carpentaria, in northern Australia. This massive die-off was preceded by a strong 2015/2016 El Niño event, resulting in lower precipitation, a drop in sea level and higher than average temperatures in northern Australia. In this study, we investigated the role of hydraulic failure in the mortality and recovery of the dominant species, Avicennia marina , 2 years after the mortality event. We measured predawn water potential (Ψ pd ) and percent loss of stem hydraulic conductivity (PLC) in surviving in iduals across a gradient of impact. We also assessed the vulnerability to drought-induced embolism (Ψ 50 ) for the species. Areas with severe canopy dieback had higher native PLC (39%) than minimally impacted areas (6%), suggesting that hydraulic recovery was ongoing. The high resistance of A. marina to water-stress-induced embolism (Ψ 50 = −9.6 MPa), indicates that severe water stress (Ψ pd & −10 MPa) would have been required to cause mortality in this species. Our data indicate that the natural gradient of water-stress enhanced the impact of El Niño, leading to hydraulic failure and mortality in A. marina growing on severely impacted (SI) zones. It is likely that lowered sea levels and less frequent inundation by seawater, combined with lower inputs of fresh water, high evaporative demand and high temperatures, led to the development of hyper-salinity and extreme water stress during the 2015/16 summer.
Hypersaline tidal flats as important “blue carbon” systems: a case study from three ecosystems
Publisher: Copernicus GmbH
Date: 22-04-2021
Abstract: Abstract. Hypersaline tidal flats (HTFs) are coastal ecosystems with freshwater deficits often occurring in arid or semi-arid regions near mangrove supratidal zones with no major fluvial contributions. Here, we estimate that organic carbon (OC), total nitrogen (TN) and total phosphorus (TP) were buried at rates averaging 21 (±6), 1.7 (±0.3) and 1.4 (±0.3) gm-2yr-1, respectively, during the previous century in three contrasting HTF systems, one in Brazil (eutrophic) and two in Australia (oligotrophic). Although these rates are lower than those from nearby mangrove, saltmarsh and seagrass systems, the importance of HTFs as sinks for OC, TN and TP may be significant given their extensive coverage. Despite the measured short-term variability between net air–saltpan CO2 influx and emission estimates found during the dry and wet season in the Brazilian HTF, the only site with seasonal CO2 flux measurements, the OC sedimentary profiles over several decades suggest efficient OC burial at all sites. Indeed, the stable isotopes of OC and TN (δ13C and δ15N) along with C:N ratios show that microphytobenthos are the major source of the buried OC in these HTFs. Our findings highlight a previously unquantified carbon as well as a nutrient sink and suggest that coastal HTF ecosystems could be included in the emerging blue carbon framework.
Land-use intensity alters both the source and fate of CO2 within eight sub-tropical estuaries
Publisher: Elsevier BV
Date: 2020
Denitrification, N-fixation and nitrogen and phosphorus fluxes in different benthic habitats and their contribution to the nitrogen and phosphorus budgets of a shallow oligotrophic sub-tropical coasta
Publisher: Springer Science and Business Media LLC
Date: 20-03-2010
Spatial Distribution of CO2, CH4, and N2O in the Great Barrier Reef Revealed Through High Resolution Sampling and Isotopic Analysis
Publisher: American Geophysical Union (AGU)
Date: 08-2021
DOI: 10.1029/2021GL092534
Abstract: Methane (CH 4 ) and nitrous oxide (N 2 O) dynamics in coastal coral reef areas are poorly understood. We measured dissolved carbon dioxide (CO 2 ) and CH 4 (with δ 13 C‐CO 2 and δ 13 C‐CH 4 isotope fractions) and N 2 O in the Great Barrier Reef (GBR) to determine spatial distributions and emissions. CO 2 (379–589 μatm) was oversaturated due to calcification and riverine sources, as indicated by depleted δ 13 C‐CO 2 values. CH 4 (1.5–13.5 nM) was also oversaturated from nearshore biogenic sources indicated by depleted δ 13 C‐CH 4 and probable offshore aerobic production. N 2 O (5.5–6.6 nM) was generally undersaturated, with uptake highest near the coast. Daily CO 2 emissions were 5826 ± 1191 tonnes, with CO 2 equivalent ( eq ) N 2 O uptake (191 ± 44 tonnes) offsetting 3.3% of CO 2 or 89% of CH 4 eq (214 ± 45 tonnes) emissions based on 20‐year global warming potentials. The GBR was a slight CO 2 and CH 4 source and N 2 O sink during our study. However, further work is required to constrain diurnal, seasonal, and spatial dynamics.
Punching above their weight: Large release of greenhouse gases from small agricultural dams
Publisher: Wiley
Date: 20-11-2018
DOI: 10.1111/GCB.14477
Abstract: Freshwater ecosystems play a major role in global carbon cycling through the breakdown of organic material and release of greenhouse gases (GHGs). Carbon dioxide (CO
The spatial and temporal drivers of pCO2, pCH4 and gas transfer velocity within a subtropical estuary.
Publisher: Elsevier BV
Date: 08-2018
Mangrove mortality in a changing climate: An overview
Publisher: Elsevier BV
Date: 12-2018
A Multifaceted Approach for Determining Sediment Provenance to Coastal Shipping Channels
Publisher: MDPI AG
Date: 29-11-2019
DOI: 10.3390/JMSE7120434
Abstract: Maintenance dredging for shipping channels is required to maintain safe and efficient navigational channels and berths in ports around the world. Sediment that refills dredged channels can enter ports via alluvial transport of eroded materials from upstream and adjacent catchments, from marine transport due to tidal currents and wind driven currents and from longshore drift. Identifying the provenance of sediment infilling navigational channels allows port operators to mitigate and manage sediment transport, potentially reducing dredging requirements and costs. Further, understanding sediment sources can inform options for beneficial reuse or disposal of dredged sediments. A multi-faceted approach was used to assess whether sediment provenance in the Port of Gladstone could be characterized. A combination of particle size analysis, rare earth element composition, carbon stable isotope ratios, strontium isotopes, and beryllium-7 radioisotopes was employed. S les were collected at accumulation locations within the navigational channel. Potential sediment sources were s led from sites of longshore drift to the south of the Port of Gladstone, and intertidal sand and mud representative of transport from currents. Fluvial sediment s les were collected during dry and wet season conditions and from the three main local catchments. Potential source sediment s les yielded identifiable differences with respect to rare earth elements, while beryllium-7 isotope analysis indicated recent deposition of sediments from mudflats or catchment within the channels. The approach used here provided insights into the source of recently deposited sediments to the dredged channels, enabling managers to make informed decisions on mitigation and management strategies.
Stable isotopes track the ecological and biogeochemical legacy of mass mangrove forest dieback in the Gulf of Carpentaria, Australia
Publisher: Copernicus GmbH
Date: 02-03-2020
DOI: 10.5194/BG-2019-468
Abstract: Abstract. A combination of elemental analysis and stable isotope analysis (SIA) was used to assess and monitor C, N and S cycling of a mangrove ecosystem that suffered mass dieback of trees in the Gulf of Carpentaria, Australia in 2015–16, attributed to an extreme drought event. Three field c aigns were conducted over a period from 2016 to 2018, at 8, 20 and 32 months after the event. S les including invertebrates, mangroves, and sediment were analysed for CNS elemental and isotopic compositions including compound-specific stable isotope analysis (CSIA) of amino acid carbon. S les collected from the impacted ecosystem were enriched in 13C, 15N and 34S relative to those from an adjacent unimpacted reference ecosystem, likely indicating lower mangrove carbon fixation, lower nitrogen fixation and lower sulfate reduction in the impacted ecosystem. For ex le, invertebrates representing the feeding types of grazing, leaf feeding, and algae feeding were more 13C enriched at the impacted site, by 1.7–4.1 ‰ and these differences did not change over the period from 2016 to 2018. The CSIA data indicated widespread 13C enrichment across five essential amino acids and all groups s led (except filter feeders) within the impacted site. Mangrove seedling and sapling populations increased substantially from 2016 to 2018 in the impacted forest, suggesting recovery of the mangrove vegetation. Recovery of CNS cycling, however, was not evident even after 32 months, suggesting a biogeochemical legacy of the mortality event. Continued monitoring of the post-dieback forest would help to predict the long-term trajectory of ecosystem recovery. In such long-term monitoring programs, SIA that can track biogeochemical changes over time can help to detect underlying biological mechanisms that drive changes and recovery of the mangrove ecosystem. To gain further insight, our use of CSIA can help show feeding dependencies in mangrove food webs and their response to disturbances.
Divergent drivers of carbon dioxide and methane dynamics in an agricultural coastal floodplain: Post-flood hydrological and biological drivers
Publisher: Elsevier BV
Date: 11-2016
High CO2 evasion during floods in an Australian subtropical estuary downstream from a modified acidic floodplain wetland
Publisher: Wiley
Date: 31-12-2014
DOI: 10.1002/LNO.10004
Importance of budgets for estimating the input of groundwater-derived nutrients to an eutrophic tidal river and estuary
Publisher: Elsevier BV
Date: 04-2014
Role of carbonate burial in Blue Carbon budgets
Publisher: Springer Science and Business Media LLC
Date: 07-03-2019
DOI: 10.1038/S41467-019-08842-6
Abstract: Calcium carbonates (CaCO 3 ) often accumulate in mangrove and seagrass sediments. As CaCO 3 production emits CO 2 , there is concern that this may partially offset the role of Blue Carbon ecosystems as CO 2 sinks through the burial of organic carbon (C org ). A global collection of data on inorganic carbon burial rates (C inorg , 12% of CaCO 3 mass) revealed global rates of 0.8 TgC inorg yr −1 and 15–62 TgC inorg yr −1 in mangrove and seagrass ecosystems, respectively. In seagrass, CaCO 3 burial may correspond to an offset of 30% of the net CO 2 sequestration. However, a mass balance assessment highlights that the C inorg burial is mainly supported by inputs from adjacent ecosystems rather than by local calcification, and that Blue Carbon ecosystems are sites of net CaCO 3 dissolution. Hence, CaCO 3 burial in Blue Carbon ecosystems contribute to seabed elevation and therefore buffers sea-level rise, without undermining their role as CO 2 sinks.
Mapping Methane and Carbon Dioxide Concentrations and δ13C Values in the Atmosphere of Two Australian Coal Seam Gas Fields
Publisher: Springer Science and Business Media LLC
Date: 18-11-2014
Insights into estuarine benthic dissolved organic carbon (DOC) dynamics using δ13C-DOC values, phospholipid fatty acids and dissolved organic nutrient fluxes
Publisher: Elsevier BV
Date: 04-2011
Geomorphic controls on fluvial carbon exports and emissions from upland swamps in eastern Australia
Publisher: Elsevier BV
Date: 03-2018
DOI: 10.1016/J.SCITOTENV.2017.08.133
Abstract: Temperate Highland Peat Sw s on Sandstone (THPSS) are upland wetlands, similar to fens in the Northern Hemisphere and are found at the headwaters of low-order streams on the plateaus of Eastern Australia. They are classified as endangered ecological communities under State and National legislation. Previous works have identified particular geomorphic characteristics that are important to carbon storage in these low energy sediment accumulation zones. Changes in the geomorphic structure of THPSS, such as channelisation, may have profound implications for carbon storage. To assess the effect of channelisation on carbon budgets in these ecosystems it is essential to identify and quantify differences in carbon export, emissions and stocks of carbon of intact sw s and those that have become channelised. We undertook seasonal s ling of the perched sw aquifers and surface waters of two intact sw s and two channelised fills in the Blue Mountains of New South Wales, Australia, to investigate differences in carbon exports and emissions between the two sw types. We found that channelised fills' mean CO
Nitrous oxide and methane dynamics in a coral reef lagoon driven by pore water exchange: Insights from automated high‐frequency observations
Publisher: American Geophysical Union (AGU)
Date: 21-04-2015
DOI: 10.1002/2015GL063126
Automated, in situ measurements of dissolved CO2, CH4, and δ13C values using cavity enhanced laser absorption spectrometry: Comparing response times of air‐water equil
Publisher: Wiley
Date: 21-03-2016
DOI: 10.1002/LOM3.10092
Electroanalytical Applications of Semiintegral and Convolution Voltammetry in Room-Temperature Ionic Liquids
Publisher: Springer International Publishing
Date: 2015
Fresh meteoric versus recirculated saline groundwater nutrient inputs into a subtropical estuary
Publisher: Elsevier BV
Date: 10-2016
The carbon dioxide evasion cycle of an intermittent first-order stream: contrasting water–air and soil–air exchange
Publisher: Springer Science and Business Media LLC
Date: 30-12-2017
The Importance of Aquatic Carbon Fluxes in Net Ecosystem Carbon Budgets: A Catchment-Scale Review
Publisher: Springer Science and Business Media LLC
Date: 27-07-2018
Reconstructing extreme climatic and geochemical conditions during the largest natural mangrove dieback on record
Publisher: Copernicus GmbH
Date: 28-09-2020
Abstract: Abstract. A massive mangrove dieback event occurred in 2015–2016 along ∼1000 km of pristine coastline in the Gulf of Carpentaria, Australia. Here, we use sediment and wood chronologies to gain insights into geochemical and climatic changes related to this dieback. The unique combination of low rainfall and low sea level observed during the dieback event had been unprecedented in the preceding 3 decades. A combination of iron (Fe) chronologies in wood and sediment, wood density and estimates of mangrove water use efficiency all imply lower water availability within the dead mangrove forest. Wood and sediment chronologies suggest a rapid, large mobilization of sedimentary Fe, which is consistent with redox transitions promoted by changes in soil moisture content. Elemental analysis of wood cross sections revealed a 30- to 90-fold increase in Fe concentrations in dead mangroves just prior to their mortality. Mangrove wood uptake of Fe during the dieback is consistent with large apparent losses of Fe from sediments, which potentially caused an outwelling of Fe to the ocean. Although Fe toxicity may also have played a role in the dieback, this possibility requires further study. We suggest that differences in wood and sedimentary Fe between living and dead forest areas reflect sediment redox transitions that are, in turn, associated with regional variability in groundwater flows. Overall, our observations provide multiple lines of evidence that the forest dieback was driven by low water availability coinciding with a strong El Niño–Southern Oscillation (ENSO) event and was associated with climate change.
An Australian blue carbon method to estimate climate change mitigation benefits of coastal wetland restoration
Publisher: Wiley
Date: 30-06-2022
DOI: 10.1111/REC.13739
Abstract: Restoration of coastal wetlands has the potential to deliver both climate change mitigation, called blue carbon, and adaptation benefits to coastal communities, as well as supporting bio ersity and providing additional ecosystem services. Valuing carbon sequestration may incentivize restoration projects however, it requires development of rigorous methods for quantifying blue carbon sequestered during coastal wetland restoration. We describe the development of a blue carbon accounting model (BlueCAM) used within the Tidal Restoration of Blue Carbon Ecosystems Methodology Determination 2022 of the Emissions Reduction Fund (ERF), which is Australia's voluntary carbon market scheme. The new BlueCAM uses Australian data to estimate abatement from carbon and greenhouse gas sources and sinks arising from coastal wetland restoration (via tidal restoration) and aligns with the Intergovernmental Panel for Climate Change guidelines for national greenhouse gas inventories. BlueCAM includes carbon sequestered in soils and biomass and avoided emissions from alternative land uses. A conservative modeled approach was used to provide estimates of abatement (as opposed to on‐ground measurements) and in doing so, this will reduce the costs associated with monitoring and verification for ERF projects and may increase participation in blue carbon projects by Australian landholders. BlueCAM encompasses multiple climate regions and plant communities and therefore may be useful to others outside Australia seeking to value blue carbon benefits from coastal wetland restoration.
New insights into the hydrogeology and groundwater flow in the Great Barrier Reef catchment, Australia, revealed through 3D modelling
Publisher: Elsevier BV
Date: 08-2020
Seasonal and temporal CO2 dynamics in three tropical mangrove creeks – A revision of global mangrove CO2 emissions
Publisher: Elsevier BV
Date: 02-2018
Tracer‐Aided Modeling in the Low‐Relief, Wet‐Dry Tropics Suggests Water Ages and DOC Export Are Driven by Seasonal Wetlands and Deep Groundwater
Publisher: American Geophysical Union (AGU)
Date: 04-2020
DOI: 10.1029/2019WR026175
Abstract: Our understanding of how wet‐dry tropical catchments process water and solutes remains limited. In this study, we attempt to gain understanding of water and dissolved organic carbon (DOC) transport, storage, and mixing in a 126 km 2 catchment of northern Australia. We developed a coupled, tracer‐aided, conceptual rainfall‐runoff model (SAVTAM) that simultaneously calculates water, isotope, and DOC‐based processes at a daily time step. The semidistributed model can account for the marked hydrological distinction between savanna woodlands and adjacent seasonal wetlands. Using the calibrated model, we tracked the fluxes and derived the age of water in fluxes and storages. Model output matched the seasonal variability, controlled by seasonal rainfall, which switched on and off water and carbon flow pathways from the savanna to seasonal wetlands and ultimately to the perennial river. Such hydrological connectivity is modulated by the karst aquifer system that continuously contributes older waters (decades to century old) to maintain relatively stable and older streamflow during the dry season (average stream water age = 9.7 to 16.2 years). Such older waters occur despite a rapid, monsoon‐driven streamflow response. The DOC fluxes were largely sourced from the wetland and riparian forest that transported DOC in the order of 1.9 t C km −2 year −1 to the stream, which was on average 90% of the total simulated DOC exports of 2 t C·km −2 ·year −1 . We conclude that coupled simulation of water and biogeochemistry is necessary to generate a more complete picture of catchment functioning, particularly in the tropics.
Response to Gallagher (2022)—the Australian Tidal Restoration for Blue Carbon method 2022 —conservative, robust, and practical
Publisher: Wiley
Date: 28-09-2023
DOI: 10.1111/REC.14027
Groundwater discharge and streams drive spatial alkalinity and pCO2 dynamics in two contrasting tropical lagoons
Publisher: Elsevier BV
Date: 2023
Factors controlling seasonal CO2 and CH4 emissions in three tropical mangrove-dominated estuaries in Australia
Publisher: Elsevier BV
Date: 12-2018
Carbon outwelling across the shelf following a massive mangrove dieback in Australia: Insights from radium isotopes
Publisher: Elsevier BV
Date: 05-2019
Drivers of carbon isotopic fractionation in a coral reef lagoon: Predominance of demand over supply
Publisher: Elsevier BV
Date: 03-2015
Rhizosphere to the atmosphere: contrasting methane pathways, fluxes and geochemical drivers across the terrestrial-aquatic wetland boundary
Publisher: Copernicus GmbH
Date: 22-01-2019
DOI: 10.5194/BG-2019-11
Abstract: Abstract. Although wetlands represent the largest natural source of atmospheric CH4, large uncertainties remain regarding the global CH4 flux. Wetland hydrological oscillations contribute to this uncertainty, dramatically altering wetland area, water table height, soil redox potentials and CH4 emissions. This study compares both terrestrial and aquatic CH4 fluxes over two distinct seasons in both permanent and seasonal remediated freshwater wetlands in subtropical Australia. We account for aquatic CH4 diffusion and ebullition rates, and plant-mediated CH4 fluxes from three distinct vegetation communities, thereby examining seasonal, diurnal and intra-habitat variability. CH4 emission rates were related to underlying sediment geochemistry. For ex le, distinct negative relationships between Fe(III) and SO42− and CH4 fluxes were observed, whereas distinct positive trends occurred between CH4 emissions and Fe(II) / AVS, where sediment Fe(III) and SO42− were depleted. The highest CH4 emissions of the seasonal wetland were measured during flooded conditions and always during daylight hours, which is consistent with soil redox potential and temperature being important co-drivers of CH4 flux. The highest CH4 fluxes were consistently emitted from the permanent wetland (1.5 to 10.5 mmol m−2 d−1), followed by the Phragmites australis community within the seasonal wetland (0.8 to 2.3 mmol m−2 d−1), whilst the lowest CH4 fluxes came from a region of forested Juncus sp. (−0.01 to 0.1 mmol m−2 d−1) which also corresponded with the highest sedimentary Fe(III) and SO42−. We suggest that wetland remediation strategies should consider geochemical profiles to help to mitigate excessive and unwanted methane emissions, especially during early system recovery periods.
Drivers of CO2 along a mangrove-seagrass transect in a tropical bay: Delayed groundwater seepage and seagrass uptake
Publisher: Elsevier BV
Date: 2019
Technical note: Coupling infrared gas analysis and cavity ring down spectroscopy for autonomous, high-temporal-resolution measurements of DIC and <i>δ</i><sup>
Publisher: Copernicus GmbH
Date: 15-03-2017
Abstract: Abstract. A new approach to autonomously determine concentrations of dissolved inorganic carbon (DIC) and its carbon stable isotope ratio (δ13C–DIC) at high temporal resolution is presented. The simple method requires no customised design. Instead it uses two commercially available instruments currently used in aquatic carbon research. An inorganic carbon analyser utilising non-dispersive infrared detection (NDIR) is coupled to a Cavity Ring-down Spectrometer (CRDS) to determine DIC and δ13C–DIC based on the liberated CO2 from acidified aliquots of water. Using a small s le volume of 2 mL, the precision and accuracy of the new method was comparable to standard isotope ratio mass spectrometry (IRMS) methods. The system achieved a s ling resolution of 16 min, with a DIC precision of ±1.5 to 2 µmol kg−1 and δ13C–DIC precision of ±0.14 ‰ for concentrations spanning 1000 to 3600 µmol kg−1. Accuracy of 0.1 ± 0.06 ‰ for δ13C–DIC based on DIC concentrations ranging from 2000 to 2230 µmol kg−1 was achieved during a laboratory-based algal bloom experiment. The high precision data that can be autonomously obtained by the system should enable complex carbonate system questions to be explored in aquatic sciences using high-temporal-resolution observations.
Mangrove pore water exchange across a latitudinal gradient
Publisher: American Geophysical Union (AGU)
Date: 14-04-2016
DOI: 10.1002/2016GL068289
Novel Use of Cavity Ring-down Spectroscopy to Investigate Aquatic Carbon Cycling from Microbial to Ecosystem Scales
Publisher: American Chemical Society (ACS)
Date: 11-2013
DOI: 10.1021/ES4027776
Abstract: Development of cavity ring-down spectroscopy (CRDS) has enabled real-time monitoring of carbon stable isotope ratios of carbon dioxide and methane in air. Here we demonstrate that CRDS can be adapted to assess aquatic carbon cycling processes from microbial to ecosystem scales. We first measured in situ isotopologue concentrations of dissolved CO2 ((12)CO2 and (13)CO2) and CH4 ((12)CH4 and (13)CH4) with CRDS via a closed loop gas equilibration device during a survey along an estuary and during a 40 h time series in a mangrove creek (ecosystem scale). A similar system was also connected to an in situ benthic chamber in a seagrass bed (community scale). Finally, a pulse-chase isotope enrichment experiment was conducted by measuring real-time release of (13)CO2 after addition of (13)C enriched phytoplankton to exposed intertidal sediments (microbial scale). Miller-Tans plots revealed complex transformation pathways and distinct isotopic source values of CO2 and CH4. Calculations of δ(13)C-DIC based on CRDS measured δ(13)C-CO2 and published fractionation factors were in excellent agreement with measured δ(13)C-DIC using isotope ratio mass spectroscopy (IRMS). The portable CRDS instrumentation used here can obtain real-time, high precision, continuous greenhouse gas data in lakes, rivers, estuaries and marine waters with less effort than conventional laboratory-based techniques.
Carbon dioxide dynamics driven by groundwater discharge in a coastal floodplain creek
Publisher: Elsevier BV
Date: 06-2013
Climate change mitigation and improvement of water quality from the restoration of a subtropical coastal wetland
Publisher: Wiley
Date: 23-05-2022
DOI: 10.1002/EAP.2620
Abstract: Coastal wetland restoration is an important activity to achieve greenhouse gas (GHG) reduction targets, improve water quality, and reach the Sustainable Development Goals. However, many uncertainties remain in connection with achieving, measuring, and reporting success from coastal wetland restoration. We measured levels of carbon (C) abatement and nitrogen (N) removal potential of restored coastal wetlands in subtropical Queensland, Australia. The site was originally a supratidal forest composed of Melaleuca spp. that was cleared and drained in the 1990s for sugarcane production. In 2010, tidal inundation was reinstated, and a mosaic of coastal vegetation (saltmarshes, mangroves, and supratidal forests) emerged. We measured soil GHG fluxes (CH 4 , N 2 O, CO 2 ) and sequestration of organic C in the trees and soil to estimate the net C abatement associated with the reference, converted, and restored sites. To assess the influence of restoration on water quality improvement, we measured denitrification and soil N accumulation. We calculated C abatement of 18.5 Mg CO 2−eq ha −1 year −1 when sugarcane land transitioned to supratidal forests, 11.0 Mg CO 2−eq ha −1 year −1 when the land transitioned to mangroves, and 6.2 Mg CO 2−eq ha −1 year −1 when the land transitioned to saltmarshes. The C abatement was due to tree growth, soil accumulation, and reduced N 2 O emissions due to the cessation of fertilization. Carbon abatement was still positive, even accounting for CH 4 emissions, which increased in the wetlands due to flooding and N 2 O production due to enhanced levels of denitrification. Coastal wetland restoration in this subtropical setting effectively reduces CO 2 emissions while providing additional cobenefits, notably water quality improvement.
Addressing calcium carbonate cycling in blue carbon accounting
Publisher: Wiley
Date: 24-10-2017
DOI: 10.1002/LOL2.10052
Uranium export from a sandy beach subterranean estuary in Australia
Publisher: Elsevier BV
Date: 11-2017
Multi-scale mapping of Australia’s terrestrial and blue carbon stocks and their continental and bioregional drivers
Publisher: Springer Science and Business Media LLC
Date: 06-2023
DOI: 10.1038/S43247-023-00838-X
Abstract: The soil in terrestrial and coastal blue carbon ecosystems is an important carbon sink. National carbon inventories require accurate assessments of soil carbon in these ecosystems to aid conservation, preservation, and nature-based climate change mitigation strategies. Here we harmonise measurements from Australia’s terrestrial and blue carbon ecosystems and apply multi-scale machine learning to derive spatially explicit estimates of soil carbon stocks and the environmental drivers of variation. We find that climate and vegetation are the primary drivers of variation at the continental scale, while ecosystem type, terrain, clay content, mineralogy and nutrients drive subregional variations. We estimate that in the top 0–30 cm soil layer, terrestrial ecosystems hold 27.6 Gt (19.6–39.0 Gt), and blue carbon ecosystems 0.35 Gt (0.20–0.62 Gt). Tall open eucalypt and mangrove forests have the largest soil carbon content by area, while eucalypt woodlands and hummock grasslands have the largest total carbon stock due to the vast areas they occupy. Our findings suggest these are essential ecosystems for conservation, preservation, emissions avoidance, and climate change mitigation because of the additional co-benefits they provide.
Editorial: Advances in understanding lateral blue carbon export from coastal ecosystems
Publisher: Frontiers Media SA
Date: 27-10-2022
Rhizosphere to the atmosphere: Contrasting methane pathways, fluxes, and geochemical drivers across the terrestrial-aquatic wetland boundary
Publisher: Copernicus GmbH
Date: 29-04-2019
Abstract: Abstract. Although wetlands represent the largest natural source of atmospheric CH4, large uncertainties remain regarding the global wetland CH4 flux. Wetland hydrological oscillations contribute to this uncertainty, dramatically altering wetland area, water table height, soil redox potentials, and CH4 emissions. This study compares both terrestrial and aquatic CH4 fluxes in permanent and seasonal remediated freshwater wetlands in subtropical Australia over two field c aigns, representing differing hydrological and climatic conditions. We account for aquatic CH4 diffusion and ebullition rates and plant-mediated CH4 fluxes from three distinct vegetation communities, thereby examining diel and intra-habitat variability. CH4 emission rates were related to underlying sediment geochemistry. For ex le, distinct negative relationships between CH4 fluxes and both Fe(III) and SO42- were observed. Where sediment Fe(III) and SO42- were depleted, distinct positive trends occurred between CH4 emissions and Fe(II) ∕ acid volatile sulfur (AVS). Significantly higher CH4 emissions (p 0.01) in the seasonal wetland were measured during flooded conditions and always during daylight hours, which is consistent with soil redox potential and temperature being important co-drivers of CH4 flux. The highest CH4 fluxes were consistently emitted from the permanent wetland (1.5 to 10.5 mmol m−2 d−1), followed by the Phragmites australis community within the seasonal wetland (0.8 to 2.3 mmol m−2 d−1), whilst the lowest CH4 fluxes came from a region of forested Juncus spp. (−0.01 to 0.1 mmol m−2 d−1), which also corresponded to the highest sedimentary Fe(III) and SO42-. We suggest that wetland remediation strategies should consider geochemical profiles to help to mitigate excessive and unwanted methane emissions, especially during early system remediation periods.
Enrichment of Radon and Carbon Dioxide in the Open Atmosphere of an Australian Coal Seam Gas Field
Publisher: American Chemical Society (ACS)
Date: 18-03-2013
DOI: 10.1021/ES304538G
Greenhouse gas emissions from tropical coastal wetlands and their alternative agricultural lands: Where significant mitigation gains lie
Publisher: Copernicus GmbH
Date: 19-03-2021
DOI: 10.5194/BG-2021-28
Abstract: Abstract. Tidal coastal wetlands are significant to the global carbon budgets through carbon sequestration and greenhouse gas (GHG CO2, CH4 and N2O) emissions. The conversion of tidal coastal wetlands to agriculture land alters soil processes changing GHG emissions. The GHG emissions associated with land-use change are important for restoration strategies that rely upon financial incentives such as carbon credits. We measured GHG fluxes from mangroves, saltmarsh and freshwater tidal forest and their alternative agricultural lands including sugarcane and ponded pastures. We investigated seasonal variations between June 2018 and February 2020 in tropical. Australia. The wet ponded pasture had by far the highest CH4 emissions with 1,231 ± 386 mg m−2 d−1, which were 200-fold higher than any other land use. Agricultural lands were the most significant sources of N2O emissions with 55 ± 9 mg m−2 d−1 from dry ponded pasture (wet-hot period) and 11 ± 3 mg m−2 d−1 from sugar cane (hot-dry period), coinciding with fertilisation. The N2O fluxes from the tidal coastal wetlands ranged between −0.55 ± 0.23 and 2.76 ± 0.45 mg m−2 d−1 throughout the study period. The highest CO2 fluxes of 20 ± 1 g m−2 d−1 were from the dry ponded pasture during the wet-hot period, while the saltmarsh had the lowest CO2 fluxes having an uptake of −1.19 ± 0.08 g m−2 d−1 in the dry-hot period. Overall, agricultural lands had significantly higher total cumulative GHG emissions (CH4 + N2O) of 7142 to 56,124 CO2-eq kg ha−1 y−1 compared to those of any type of tidal coastal wetlands, which ranged between 144 and 884 CO2-eq kg ha−1 y−1. Converting agricultural land, particularly wet ponded pasture, to tidal coastal wetlands could provide large GHG mitigation gains and potential financial incentives.
Alkalinity production coupled to pyrite formation represents an unaccounted blue carbon sink
Publisher: Wiley
Date: 17-08-2020
Examining 239+240 Pu, 210 Pb and historical events to determine carbon, nitrogen and phosphorus burial in mangrove sediments of Moreton Bay, Australia
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.JENVRAD.2015.04.018
Abstract: Two sediment cores were collected in a mangrove forest to construct geochronologies for the previous century using natural and anthropogenic radionuclide tracers. Both sediment cores were dated using (239+240)Pu global fallout signatures as well as (210)Pb, applying both the Constant Initial Concentration (CIC) and the Constant Rate of Supply (CRS) models. The (239+240)Pu and CIC model are interpreted as having comparable sediment accretion rates (SAR) below an apparent mixed region in the upper ∼5 to 10 cm. In contrast, the CRS dating method shows high sediment accretion rates in the uppermost intervals, which is substantially reduced over the lower intervals of the 100-year record. A local anthropogenic nutrient signal is reflected in the high total phosphorus (TP) concentration in younger sediments. The carbon/nitrogen molar ratios and δ(15)N values further support a local anthropogenic nutrient enrichment signal. The origin of these signals is likely the treated sewage discharge to Moreton Bay which began in the early 1970s. While the (239+240)Pu and CIC models can only produce rates averaged over the intervals of interest within the profile, the (210)Pb CRS model identifies elevated rates of sediment accretion, organic carbon (OC), nitrogen (N), and TP burial from 2000 to 2013. From 1920 to 2000, the three dating methods provide similar OC, N and TP burial rates, ∼150, 10 and 2 g m(-2) year(-1), respectively, which are comparable to global averages.
Shifts in methanogenic archaea communities and methane dynamics along a subtropical estuarine land use gradient
Publisher: Public Library of Science (PLoS)
Date: 24-11-2020
DOI: 10.1371/JOURNAL.PONE.0242339
Abstract: In coastal aquatic ecosystems, prokaryotic communities play an important role in regulating the cycling of nutrients and greenhouse gases. In the coastal zone, estuaries are complex and delicately balanced systems containing a multitude of specific ecological niches for resident microbes. Anthropogenic influences (i.e. urban, industrial and agricultural land uses) along the estuarine continuum can invoke physical and biochemical changes that impact these niches. In this study, we investigate the relative abundance of methanogenic archaea and other prokaryotic communities, distributed along a land use gradient in the subtropical Burnett River Estuary, situated within the Great Barrier Reef catchment, Australia. Microbiological assemblages were compared to physicochemical, nutrient and greenhouse gas distributions in both pore and surface water. Pore water s les from within the most urbanised site showed a high relative abundance of methanogenic Euryarchaeota (7.8% of all detected prokaryotes), which coincided with elevated methane concentrations in the water column, ranging from 0.51 to 0.68 μM at the urban and sewage treatment plant (STP) sites, respectively. These sites also featured elevated dissolved organic carbon (DOC) concentrations (0.66 to 1.16 mM), potentially fuelling methanogenesis. At the upstream freshwater site, both methane and DOC concentrations were considerably higher (2.68 μM and 1.8 mM respectively) than at the estuarine sites (0.02 to 0.66 μM and 0.39 to 1.16 mM respectively) and corresponded to the highest relative abundance of methanotrophic bacteria. The proportion of sulfate reducing bacteria in the prokaryotic community was elevated within the urban and STP sites (relative abundances of 8.0%– 10.5%), consistent with electron acceptors with higher redox potentials (e.g. O 2 , NO 3 - ) being scarce. Overall, this study showed that ecological niches in anthropogenically altered environments appear to give an advantage to specialized prokaryotes invoking a potential change in the thermodynamic landscape of the ecosystem and in turn facilitating the generation of methane–a potent greenhouse gas.
Coral Reef Calcification and Production After the 2016 Bleaching Event at Lizard Island, Great Barrier Reef
Publisher: American Geophysical Union (AGU)
Date: 06-2019
DOI: 10.1029/2018JC014698
Large variability in organic carbon and CaCO3 burial in seagrass meadows: a case study from three Australian estuaries
Publisher: Inter-Research Science Center
Date: 09-05-2019
DOI: 10.3354/MEPS12955
Constraining the annual groundwater contribution to the water balance of an agricultural floodplain using radon: The importance of floods
Publisher: American Geophysical Union (AGU)
Date: 2017
DOI: 10.1002/2016WR019735
Alkalinity Production Coupled to Pyrite Formation Represents an Unaccounted Blue Carbon Sink
Publisher: American Geophysical Union (AGU)
Date: 04-2021
DOI: 10.1029/2020GB006785
Abstract: Blue carbon ecosystems, including mangroves, saltmarshes, and seagrasses, mitigate climate change by storing atmospheric carbon. Previous blue carbon research has focused on organic carbon stocks. However, recent studies suggest that lateral inorganic carbon export might be equally important. Lateral export is a long‐term carbon sink if carbon is exported as alkalinity (TAlk) produced via sulfate reduction coupled to pyrite formation. This study evaluates drivers of pyrite formation in blue carbon ecosystems, compares pyrite production to TAlk outwelling rates, and estimates global pyrite stocks in mangroves. We quantified pyrite stocks in mangroves, saltmarshes, and seagrasses along a latitudinal gradient on the Australian East Coast, including a mangrove dieback area, and in the Everglades (Florida, USA). Our results indicate that pyrite stocks were driven by a combination of biomass, tidal litude, sediment organic carbon, sediment accumulation rates, rainfall, latitude, temperature, and iron availability. Pyrite stocks were three‐times higher in mangroves (103 ± 61 Mg/ha) than in saltmarshes (30 ± 30 Mg/ha) and seagrasses (32 ± 1 Mg/ha). Mangrove pyrite stocks were linearly correlated to TAlk export at sites where sulfate reduction was the dominant TAlk producing process. However, pyrite generation could not explain all TAlk outwelling. We present the first global model estimating pyrite stocks in mangroves, giving a first‐order estimate of 197 Mg/ha (RMSE = 24 Mg/ha). In mangroves, estimated global TAlk production coupled to pyrite formation (∼3 mol/m 2 /y) is equal to ∼24% of their global carbon burial rate, highlighting the importance of including TAlk export in future blue carbon budgets.
Tree stem methane emissions from subtropical lowland forest (Melaleuca quinquenervia) regulated by local and seasonal hydrology
Publisher: Springer Science and Business Media LLC
Date: 09-11-2020
A Small Nimble In Situ Fine-Scale Flux Method for Measuring Tree Stem Greenhouse Gas Emissions and Processes (S.N.I.F.F)
Publisher: Springer Science and Business Media LLC
Date: 11-03-2020
Assessing groundwater-surface water connectivity using radon and major ions prior to coal seam gas development (Richmond River Catchment, Australia)
Publisher: Elsevier BV
Date: 10-2016
TECHNICAL NOTE: Coupling infrared gas analysis and cavity ring down spectroscopy for autonomous, high temporal resolution measurements of DIC and δ<sup>13</sup>C-DIC
Publisher: Copernicus GmbH
Date: 22-11-2016
DOI: 10.5194/BG-2016-503
Abstract: Abstract. A new approach to autonomously determine concentrations of dissolved inorganic carbon (DIC) and its carbon stable isotope ratio (δ13C-DIC) at high temporal resolution is presented. The simple method requires no customised design. Instead it uses two commercially available instruments currently used in aquatic carbon research. An inorganic carbon analyser utilising non-dispersive infrared detection (NDIR) is coupled to a Cavity Ring-down Spectrometer (CRDS) to determine DIC and δ13C-DIC based on the liberated CO2 from acidified aliquots of water. Using a small s le volume of 2 ml, the precision and accuracy of the new method was comparable to standard isotope ratio mass spectrometry (IRMS) methods. The system achieved a s ling resolution of 16 mins, with a DIC precision of ±1.5 to 2 µmol kg−1 and δ13C-DIC precision of ±0.14 ‰ for concentrations spanning 1000 to 3600 µmol kg−1. Accuracy of 0.1 ± 0.06 ‰ based on DIC concentrations ranging from 2000 µmol kg−1 to 2230 µmol kg−1 was achieved during a laboratory-based algal bloom experiment. The high precision data that can be autonomously obtained by the system should enable complex carbonate system questions to be explored in aquatic sciences using high temporal resolution observations.
Coastal carbon cycle changes following mangrove loss
Publisher: Wiley
Date: 02-07-2020
DOI: 10.1002/LNO.11476
Abstract: Global mangrove loss is occurring from deforestation and extreme climatic events, but changes to the coastal carbon cycle following mangrove mortality and/or loss are not well understood. In 2015/2016, a massive climate‐driven mangrove dieback event occurred over ~ 1000 km of Australian coastline. To assess carbon loss following mortality, carbon fluxes in adjacent living and dead forest areas were compared 8 and 20 months postforest dieback. Dead areas experienced an increase in soil CO 2 efflux by ~ 189%, and a decrease in oceanic dissolved inorganic carbon (DIC) outwelling of ~ 50% relative to living areas. DIC outwelling (predominantly carbonate alkalinity) and soil CO 2 efflux accounted for 81% and 16% of losses from the living forest, in comparison to 51% and 47%, respectively, from the dead forest. The dieback drove a shift from a dominance of oceanic carbon outwelling to increased atmospheric CO 2 emissions and decreased alkalinity exports. This shift was likely driven by increased oxygen sediment permeation and the loss of mangrove net primary productivity. Combining our new observations with literature data, we found a logarithmic relationship between soil carbon loss and time since mangrove loss. Using this relationship, we estimate ongoing global carbon losses from historical mangrove deforestation and dieback could be 13.7 ± 9.4 Tg C yr −1 , which is eightfold higher than previous estimates and offsets global mangrove carbon burial by ~ 60%. Even if no future deforestation occurred, we estimate ongoing carbon losses to the atmosphere and ocean from current global mangrove losses of 27 Tg C over the next 30 yr.
CO2 and CH4 effluxes across six land uses in coastal wetlands of North Sumatra
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-13486
Abstract: & & Mangrove and other coastal wetlands such as saltmarsh and seagrass are termed & #8216 blue carbon& #8217 ecosystems due to their substantial capacity for carbon storage and sequestration over a long-term time scale. Policymakers and stakeholders are currently promoting mangroves into national carbon management as part of nature-based climate change mitigation and adaptation strategy. Unfortunately, global mangroves area with particularly in the tropics is decreasing at a rapid rate due to land-use and land-cover change (LULCC). Yet, there has been limited study of carbon emissions impacted by multiple mangrove conversions at the landscape scale. Here we assessed spatio-temporal patterns of soil CO& sub& & /sub& and CH& sub& & /sub& effluxes across six land uses, namely mangroves converted to 15 yrs oil palm, 20 yrs coconut, and 20 yrs aquaculture (pond wall and water surface), as well as newly logged mangrove, 10 yrs planted mangrove, and undisturbed mangrove forests reference in North Sumatra, Indonesia. Direct measurement of soil CO& sub& & /sub& and CH& sub& & /sub& effluxes were performed by using an ultra-portable LGR gas analyser during low tide condition between 08.00 and 16.00, with triplicated PVC 10-inch diameter and 25 cm height opaque static chambers (closed system) were installed at each land use in September-October 2021 -- representing wet season in the study site. The soil CO& sub& & /sub& and CH& sub& & /sub& effluxes were collected three times for each chamber and 3 days of measurement during this field c aign with a total of 193 measurements were performed. We observed that the top three highest soil CO& sub& & /sub& and CH& sub& & /sub& effluxes were among aquaculture pond wall soils (591& #177 mgCO& sub& & /sub& m& sup& & /sup& h& sup& -1& /sup& and 0.40& #177 .17 mgCH& sub& & /sub& m& sup& & /sup& h& sup& -1& /sup& ), logged mangroves (480& #177 mgCO& sub& & /sub& m& sup& & /sup& h& sup& -1& /sup& and 3.21& #177 .34 mgCH& sub& & /sub& m& sup& & /sup& h& sup& -1& /sup& ), and natural mangroves (274& #177 mgCO& sub& & /sub& m& sup& & /sup& h& sup& -1& /sup& and 0.58& #177 .28 mgCH& sub& & /sub& m& sup& & /sup& h& sup& -1& /sup& ). By contrast, relatively low effluxes (& 200 mgCO& sub& & /sub& m& sup& & /sup& h& sup& -1& /sup& and & 0.1 mgCH& sub& & /sub& m& sup& & /sup& h& sup& -1& /sup& ) were observed across other land-use types. Our preliminary results suggest that the variation of soil CO& sub& & /sub& and CH& sub& & /sub& in our study sites may be controlled by the duration of the disturbances, particularly we observed the highest CO& sub& & /sub& and CH& sub& & /sub& effluxes at newly (occurred at the same year with our measurement) constructed pond wall and logged mangrove locations. On the other hand, low CO& sub& & /sub& and CH& sub& & /sub& effluxes were observed at both oil palm and coconut plantations. These new land uses were constructed more than 10 years ago with the application of drainage and tidal blocking. Our current limited data constraint further essential factors that commonly control CO& sub& & /sub& and CH& sub& & /sub& in the coastal wetlands, such as tidal elevation, bioturbation, seasonal variation, and soil properties. Overall, our dataset will be essential to guide policymakers in related to the improvement of land-based low carbon development and climate change mitigation strategies for Indonesia to meet the targeted 29% of unconditional carbon emissions reduction by 2030 as outlined in the Nationally Determined Contributions (NDCs) as part of the Paris Agreement.& &
Cultural Competence of Australian Dental Students
Publisher: Research Square Platform LLC
Date: 20-08-2020
DOI: 10.21203/RS.3.RS-54665/V1
Abstract: Background: Australia possesses a highly multicultural demographic, and thus dental practitioners are likely to encounter culturally and linguistically erse in iduals regularly. It is important for dental practitioners to be culturally competent, however, cultural competency education is highly variable in the curricula of dentistry and oral health courses in Australia, and research is largely limited to dentistry students. This study aims to investigate and compare perceived attitudes, beliefs and practices of cultural competence amongst first and final year Doctor of Dental Surgery (DDS) and Bachelor of Oral Health (BOH) students at the University of Melbourne Dental School. Methods: Following ethics approval, anonymous questionnaires were completed by 213 participants. The questionnaire was adapted from Schwarz’s Healthcare Provider Cultural Competence Instrument (HPCCI) and consisted of five scales. Data was analysed using SPSS V 24.0 software. Results: A total of 213 students participated in this study (response rate = 88%) The majority of participants were female (n=114, 53.5%) and the mean age of 23.5 years (range 18 - 40). The majority of participants were Australian born (n=110) with 74.6 percent (n=159) first generation Australians. Participants who identified as Australian represented 35.7 percent (n=76) with 66.1 percent (n=141) identified as partly Australian. Multivariate analysis indicated that, after controlling for other independent variables in the model, those who had the highest cultural competence score were female, who self-identify as “Australian”, who were in the final year. Furthermore, those who were in the final BOH year scored significatively higher than final year DDS students. Conclusion: The findings of this study suggest that there is a significant difference in students self-reported cultural competence at different stages of their education. This may be attributed to differences in cultural competence education, scope of practice and the type of patient encounters that students may experience. Future research should involve follow up to create longitudinal data, as well as research at other dental schools in Australia and overseas.
Supplementary material to "Greenhouse gas emissions from tropical coastal wetlands and their alternative agricultural lands: Where significant mitigation gains lie"
Publisher: Copernicus GmbH
Date: 19-03-2021
Operationalizing marketable blue carbon
Publisher: Elsevier BV
Date: 05-2022
Applying cavity ring-down spectroscopy for the measurement of dissolved nitrous oxide concentrations and bulk nitrogen isotopic composition in aquatic systems: Correcting for interferences and field a
Publisher: Wiley
Date: 18-05-2015
DOI: 10.1002/LOM3.10032
Hydrological Versus Biological Drivers of Nutrient and Carbon Dioxide Dynamics in a Coastal Lagoon
Publisher: Springer Science and Business Media LLC
Date: 20-02-2019
Stable isotopes track the ecological and biogeochemical legacy of mass mangrove forest dieback in the Gulf of Carpentaria, Australia
Publisher: Copernicus GmbH
Date: 18-11-2020
Abstract: Abstract. A combination of elemental analysis, bulk stable isotope analysis (bulk SIA) and compound-specific stable isotope analysis of amino acids (CSIA-AA) was used to assess and monitor carbon (C), nitrogen (N) and sulfur (S) cycling of a mangrove ecosystem that suffered mass dieback of trees in the Gulf of Carpentaria, Australia in 2015–2016, attributed to an extreme drought event. Three field c aigns were conducted 8, 20 and 32 months after the event over a period from 2016 to 2018 to obtain biological time-series data. Invertebrates and associated organic matter including mangroves and sediments from the impacted ecosystem showed enrichment in 13C, 15N and 34S relative to those from an adjacent unimpacted reference ecosystem, likely indicating lower mangrove carbon fixation, lower nitrogen fixation and lower sulfate reduction in the impacted ecosystem. For ex le, invertebrates representing the feeding types of grazing, leaf feeding and algae feeding were more 13C enriched at the impacted site, by 1.7 ‰–4.1 ‰, and these differences did not change over the period from 2016 to 2018. The CSIA-AA data indicated widespread 13C enrichment across five essential amino acids and all groups s led (except filter feeders) within the impacted site. The seedling density increased from 0.2 m−2 in 2016 to 7.1 m−2 in 2018 in the impacted forest, suggesting recovery of the vegetation. Recovery of CNS cycling, however, was not evident even after 32 months, suggesting a biogeochemical legacy of the mortality event. Continued monitoring of the post-dieback forest is required to predict the long-term trajectory of ecosystem recovery. This study shows that time-series SIA can track biogeochemical changes over time and evaluate recovery of an impacted ecosystem from an extreme event.
Dissolved carbon, greenhouse gases, and δ13C dynamics in four estuaries across a land use gradient
Publisher: Springer Science and Business Media LLC
Date: 2019
Atmospheric Carbon Dioxide and Changing Ocean Chemistry
Publisher: Springer Nature Switzerland
Date: 2023
DOI: 10.1007/978-3-031-10127-4_11
Abstract: “ They call it life, we call it pollution ” is an infamous quote which ignores many facts about why carbon dioxide (CO 2 ) poses a significant problem for the ocean. But before we get to this, let’s start at the beginning. All organisms on Earth require a particular set of elements for growth. In the case of plants, these elements are needed to synthesise organic matter in a process called primary production via photosynthesis, and in the case of animals, these elements are directly assimilated by either consuming plant material or by preying on other animals. In this respect, one of the key elements is carbon. Being the molecular backbone for a number of vital organic compounds such as sugars, proteins and nucleic acids (containing genetic information), carbon can be considered as the building block of life.
Groundwater discharge into an estuary using spatially distributed radon time series and radium isotopes
Publisher: Elsevier BV
Date: 09-2015
Carbon dioxide and methane emissions from an artificially drained coastal wetland during a flood: Implications for wetland global warming potential
Publisher: American Geophysical Union (AGU)
Date: 08-2014
DOI: 10.1002/2013JG002544
Manganese and iron release from mangrove porewaters: A significant component of oceanic budgets?
Publisher: Elsevier BV
Date: 08-2016
Hot spot of CH4 production and diffusive flux in rivers with high urbanization
Publisher: Elsevier BV
Date: 10-2021
iAMES: An inexpensive, Automated Methane Ebullition Sensor
Publisher: American Chemical Society (ACS)
Date: 22-05-2019
Abstract: Atmospheric concentrations of methane have increased ∼2.4 fold since the industrial revolution with wetlands and inland waters representing the largest source of methane to the atmosphere. Substantial uncertainties remain in global methane budgets, due in part to the lack of adequate techniques and detailed measurements to assess ebullition in aquatic environments. Here, we present details of a low cost (∼$120 US per unit) ebullition sensor that autonomously logs both volumetric ebullition rate and methane concentrations. The sensor combines a traditional funnel bubble trap with an Arduino logger, a pressure sensor, thermal conductivity methane sensor, and a solenoid valve. Powered by three AA batteries, the sensor can measure autonomously for three months when programmed for a s ling frequency of 30 min. For field testing, four sensors were deployed for six weeks in a small lake. While ebullition was spatially and temporally variable, a distinct diurnal trend was observed with the highest rates from mid-morning to early afternoon. Ebullition rates were similar for all four sensors when integrated over the s ling period. The widespread deployment of low cost automated ebullition sensors such as the iAMES described here will help constrain one of the largest uncertainties in the global methane budget.
Carbon self-utilization may assist Caulerpa taxifolia invasion
Publisher: Wiley
Date: 28-08-2011
Are global mangrove carbon stocks driven by rainfall?
Publisher: American Geophysical Union (AGU)
Date: 10-2016
DOI: 10.1002/2016JG003510
Methane emissions partially offset “blue carbon” burial in mangroves
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-2018
Abstract: Water and sediment methane emissions have the potential to offset “blue carbon” burial in mangrove coastal ecosystems.
Estuarine canal estate waters: Hotspots of CO2 outgassing driven by enhanced groundwater discharge?
Publisher: Elsevier BV
Date: 12-2014
Stable isotopes reduce parameter uncertainty of an estuarine carbon cycling model
Publisher: Elsevier BV
Date: 05-2016
Linking climatic-driven iron toxicity and water stress to a massive mangrove dieback
Publisher: Copernicus GmbH
Date: 16-01-2020
DOI: 10.5194/BG-2019-478
Abstract: Abstract. A massive mangrove dieback event occurred in 2015/2016 along ~ 1000 km of pristine coastline in the Gulf of Carpentaria, Australia. To gain insights into dieback drivers, we combine sediment and wood chronologies to analyze geochemical and climatic changes. The unique combination of low rainfall and low sea level observed during the dieback event was unprecedented in the previous three decades. Multiple lines of evidence from iron (Fe) chronologies in wood and sediment, wood densities and mangrove water use efficiency suggest low water availability within the dead mangrove forest. Wood and sediment chronologies suggest a rapid and large mobilization of sedimentary Fe, which was likely associated with pyrite oxidation within mangrove sediments. High resolution elemental analysis of wood cross sections revealed 30–90 fold increase in Fe concentrations in dead mangrove areas just prior to mortality. Fe concentrations in wood s les correlated strongly with the El Niño Southern Oscillation (ENSO) index, suggesting ENSO was a major driver of Fe mobilization. Large Fe losses from sediments during the dieback are consistent with Fe uptake in the trees, further implying sediment pyrite oxidation. If our data are representative of the entire dieback region, we estimate that the dieback drove the mobilization and loss of 50 ± 173 Gg Fe, equivalent to 8–50 % of annual global atmospheric Fe deposition into the oceans, which is one of the major drivers of surface ocean productivity. Overall, our observations support the hypothesis that the forest dieback was associated with low water availability and Fe toxicity driven by a strong ENSO event.
Methane and carbon dioxide dynamics in a subtropical estuary over a diel cycle: Insights from automated in situ radioactive and stable isotope measurements
Publisher: Elsevier BV
Date: 2015
Groundwater–surface water exchange in a mangrove tidal creek: Evidence from natural geochemical tracers and implications for nutrient budgets
Publisher: Elsevier BV
Date: 10-2013
Bark-dwelling methanotrophic bacteria decrease methane emissions from trees
Publisher: Research Square Platform LLC
Date: 03-12-2020
DOI: 10.21203/RS.3.RS-119818/V1
Abstract: Tree stems are an important and unconstrained source of methane, yet it is uncertain if there are internal microbial controls (i.e. methanotrophy) within tree bark, that may reduce methane emissions. Using multiple lines of evidence, we demonstrate here that unique microbial communities dominated by methane oxidising bacteria (MOB) dwell within bark of Melaleuca quinquenervia , a common, invasive and globally distributed lowland species. Laboratory incubations of methane inoculated M. quinquenervia bark reveal methane consumption (up to 96.3 µmol m -2 bark d -1 ) and distinct isotopic δ 13 C-CH 4 enrichment characteristic of MOB. Molecular analysis indicates unique microbial communities reside within the bark, with methane-oxidising bacteria primarily from the genus Methylomonas comprising up to 25 % of the total microbial community. Methanotroph abundance was linearly correlated to methane uptake rates (R 2 = 0.76, p = 0.006). Finally, field-based methane oxidation inhibition experiments demonstrate that bark-dwelling MOB reduce methane emissions by 36 ± 5 %. These multiple, complementary lines of evidence indicate that bark-dwelling MOB represent a novel and potentially significant methane sink, and an important frontier for further research.
Estuaries as Sources and Sinks of N2O Across a Land Use Gradient in Subtropical Australia
Publisher: American Geophysical Union (AGU)
Date: 05-2018
DOI: 10.1029/2017GB005826
Stream respiration exceeds CO2 evasion in a low-energy, oligotrophic tropical stream
Publisher: Wiley
Date: 12-03-2023
DOI: 10.1002/LNO.12334
Abstract: Carbon dioxide (CO 2 ) can be either imported to streams through groundwater and subsurface inputs of soil‐respired CO 2 or produced internally through stream metabolism. The contribution of each source to the CO 2 evasion flux from streams is not well quantified, especially in the tropics, an underrepresented region in carbon (C) cycling studies. We used high‐frequency measurements of dissolved O 2 and CO 2 concentrations to estimate the potential contribution of stream metabolism to the CO 2 evasion flux in a tropical lowland headwater stream. We found that the stream was heterotrophic all year round, with net ecosystem productivity (NEP) values ranging from 0.84 to 4.06 g C m −2 d −1 (median 1.29 g C m −2 d −1 here we expressed gross primary productivity (GPP) as a negative flux and ecosystem respiration (ER) as a positive flux). Positive NEP values were the result of a relatively low and stable GPP through the seasons, compared to a higher and more variable ER favored by the high temperatures and organic matter availability, particularly during the wet season. The CO 2 evasion flux was relatively low due to low turbulence (median: 1.09 g C m −2 d −1 ). As a result, daily NEP rates exceeded the CO 2 evasion flux with a potential contribution of 129% (median 120–175% interquartile range), despite the strong seasonal changes in flow regime and landscape connectivity. The CO 2 excess was likely transported downstream, where it was ultimately emitted to the atmosphere. Our results highlight the overwhelming importance of ER to the C cycle of low‐energy, oligotrophic tropical streams.
Are mangroves drivers or buffers of coastal acidification? Insights from alkalinity and dissolved inorganic carbon export estimates across a latitudinal transect
Publisher: American Geophysical Union (AGU)
Date: 05-2016
DOI: 10.1002/2015GB005324
Carbon cycling and exports over diel and flood-recovery timescales in a subtropical rainforest headwater stream
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.SCITOTENV.2016.01.082
Abstract: Catchment headwaters comprise the majority of all stream length globally, however, carbon (C) dynamics in these systems remains poorly understood. We combined continuous measurements of pCO2 and radon ((222)Rn, a natural groundwater tracer) with discrete s ling for particulate organic, dissolved organic and inorganic carbon (POC, DOC, and DIC) to assess the short-term carbon dynamics of a pristine subtropical headwater stream in Australia, over contrasting hydrologic regimes of drought, flash-flooding and recovery. Observations over 23days revealed a shift from carbon losses dominated by CO2 outgassing under conditions of low flow (66.4±0.4% of carbon export) to downstream exports of carbon during the flood (87.8±9.7% of carbon export). DOC was the dominant form of downstream exports throughout the study (DOC:DIC:POC=0.82:0.05:0.13). The broadest diel variability among variables occurred during the drought phase, with diel variability up to 662μatmd(-1) (or 27μM[CO2*]d(-1)), 17μMd(-1) and 268Bqm(-3)d(-1) for pCO2, dissolved oxygen and (222)Rn, respectively. Diel dynamics indicated multiple interrelated drivers of stream water chemistry including groundwater seepage and in-stream metabolism. The catchment exported terrestrial carbon throughout the field c aign, with a mean net stream flux of 4.7±7.8mmolCm(-2)(catchment area)d(-1) which is equivalent to 1.4±2.3% of the estimated local terrestrial net primary production. Our observations highlight the importance of accounting for hydrological extremes when assessing the carbon budgets and ecosystem metabolism of headwater streams, and provide a first estimate of aquatic carbon exports from a pristine Australian subtropical rainforest.
Dissolved radon and uranium in groundwater in a potential coal seam gas development region (Richmond River Catchment, Australia)
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.JENVRAD.2016.01.014
Abstract: The extraction of unconventional gas resources such as shale and coal seam gas (CSG) is rapidly expanding globally and often prevents the opportunity for comprehensive baseline groundwater investigations prior to drilling. Unconventional gas extraction often targets geological layers with high naturally occurring radioactive materials (NORM) and extraction practices may possibly mobilise radionuclides into regional and local drinking water resources. Here, we establish baseline groundwater radon and uranium levels in shallow aquifers overlying a potential CSG target formation in the Richmond River Catchment, Australia. A total of 91 groundwater s les from six different geological units showed highly variable radon activities (0.14-20.33 Bq/L) and uranium levels (0.001-2.77 μg/L) which were well below the Australian Drinking Water Guideline values (radon 100 Bq/L and uranium 17 μg/L). Therefore, from a radon and uranium perspective, the regional groundwater does not pose health risks to consumers. Uranium could not explain the distribution of radon in groundwater. Relatively high radon activities (7.88 ± 0.83 Bq/L) in the fractured Lismore Basalt aquifer coincided with very low uranium concentrations (0.04 ± 0.02 μg/L). In the Quaternary Sediments aquifers, a positive correlation between U and HCO3(-) (r(2) = 0.49, p < 0.01) implied the uranium was present as uranyl-carbonate complexes. Since NORM are often enriched in target geological formations containing unconventional gas, establishing radon and uranium concentrations in overlying aquifers comprises an important component of baseline groundwater investigations.
High pore-water derived CO2 and CH4 emissions from a macro-tidal mangrove creek in the Amazon region
Publisher: Elsevier BV
Date: 02-2019
Mangrove outwelling is a significant source of oceanic exchangeable organic carbon
Publisher: Wiley
Date: 29-01-2017
DOI: 10.1002/LOL2.10031
Abstract: Exchangeable dissolved organic carbon (EDOC) makes up a significant proportion of the oceanic dissolved organic carbon (DOC) pool, yet EDOC sources to the coastal ocean are poorly constrained. We measured the exchange of EDOC and concentrations of EDOC and DOC in mangrove waters over a 26° latitudinal gradient. A clear latitudinal trend was observed, with the highest EDOC concentrations in the tropics. EDOC exports to the coastal ocean were 4.7 ± 1.9 mmol m −2 d −1 , equivalent to 11% of DOC exports (42.1 ± 6.7 mmol m −2 d −1 ). Pore‐water and groundwater exchange were minor sources of EDOC. EDOC concentrations were equal to 13% ± 4% of DOC concentrations. Based on previous global DOC export estimates, and our EDOC : DOC ratios, mangroves outwell 3.1 Tg C yr −1 as EDOC, equivalent to ∼ 60% of the global EDOC flux from the ocean to the atmosphere. However, seasonality of mangrove EDOC cycling requires further research.
Varying Biological Activity and Wind Stress Affect the DMS Response during the SAGE Iron Enrichment Experiment
Publisher: MDPI AG
Date: 09-04-2020
DOI: 10.3390/JMSE8040268
Abstract: Surface dissolved dimethylsulfide (DMS) and depth-integrated dimethylsulfoniopropionate (DMSP) measurements were made from March to April 2004 during the SOLAS Air–Sea Gas Exchange Experiment (SAGE), a multiple iron enrichment experiment in subantarctic waters SE of New Zealand. During the first two iron enrichments, chl a and DMS production were constrained, but during the third enrichment, large pulses of DMS occurred in the fertilised IN patch, compared with the unfertilised OUT patch. During the third and fourth iron infusions, total chl a concentrations doubled from 0.52 to 1.02 µg/L. Hapto8s and prasinophytes accounted for 50%, and 20%, respectively, of total chl a. The large pulses of DMS during the third iron enrichment occurred during high dissolved DMSP concentrations and wind strength changes in dinoflagellate, haptophyte, and cyanobacteria biomass and increased microzooplankton grazing that exerted a top down control on phytoplankton production. A further fourth iron enrichment did cause surface waters to increase in DMS, but the effect was not as great as that recorded in the third enrichment. Differences in the biological response between SAGE and several other iron enrichment experiments were concluded to reflect microzooplankton grazing activities and the microbial loop dominance, resulting from mixing of the MLD during storm activity and high winds during iron enrichment.
Changing sediment and surface water processes increase CH4 emissions from human-impacted estuaries
Publisher: Elsevier BV
Date: 07-2020
Development of an improved hydrogeological and hydro-geochemical conceptualization of a complex aquifer system in Ethiopia
Publisher: Springer Science and Business Media LLC
Date: 26-08-2020
Benthic fluxes of dissolved organic carbon in three temperate Australian estuaries: Implications for global estimates of benthic DOC fluxes
Publisher: American Geophysical Union (AGU)
Date: 21-12-2010
DOI: 10.1029/2010JG001433
Carbon outwelling and outgassing vs. burial in an estuarine tidal creek surrounded by mangrove and saltmarsh wetlands
Publisher: Wiley
Date: 02-01-2019
DOI: 10.1002/LNO.11090
Groundwater-derived dissolved inorganic and organic carbon exports from a mangrove tidal creek: The missing mangrove carbon sink?
Publisher: Wiley
Date: 09-02-2013
Drivers of pCO2 variability in two contrasting coral reef lagoons: The influence of submarine groundwater discharge
Publisher: American Geophysical Union (AGU)
Date: 04-2014
DOI: 10.1002/2013GB004598
Quantity and quality of organic matter (detritus) drives N2 effluxes (net denitrification) across seasons, benthic habitats, and estuaries
Publisher: American Geophysical Union (AGU)
Date: 12-11-2015
DOI: 10.1002/2013GB004631
The role of porewater exchange as a driver of CO2 flux to the atmosphere in a temperate estuary (Squamish, Canada)
Publisher: Springer Science and Business Media LLC
Date: 28-05-2019
The legacy and drivers of groundwater nutrients and pesticides in an agriculturally impacted Quaternary aquifer system
Publisher: Elsevier BV
Date: 2021
Mangroves as a Source of Alkalinity and Dissolved Carbon to the Coastal Ocean: A Case Study from the Everglades National Park, Florida
Publisher: Wiley
Date: 05-05-2020
Mapping ecosystem processes and function across shallow seascapes
Publisher: Elsevier BV
Date: 02-2011
The contribution of denitrification and burial to the nitrogen budgets of three geomorphically distinct Australian estuaries: Importance of seagrass habitats
Publisher: No publisher found
Date: 2016
DOI: 10.1002/LNO.10280
Erratum to: The carbon dioxide evasion cycle of an intermittent first-order stream: contrasting water–air and soil–air exchange (Biogeochemistry, (2017), 132, 1-2, (87-102), 10.1007/s10533-016-0289-2)
Publisher: Springer Science and Business Media LLC
Date: 29-05-2017
Spatial and temporal variability of CO2 and CH4 gas transfer velocities and quantification of the CH4 microbubble flux in mangrove dominated estuaries
Publisher: Wiley
Date: 02-12-2016
DOI: 10.1002/LNO.10444
Carbon dioxide dynamics in a lake and a reservoir on a tropical island (Bali, Indonesia)
Publisher: Public Library of Science (PLoS)
Date: 11-06-2018
Isotopic evidence for axial tree stem methane oxidation within subtropical lowland forests
Publisher: Copernicus GmbH
Date: 03-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-1923
Abstract: & & Knowledge regarding processes, pathways and mechanisms that may moderate methane (CH& sub& & /sub& ) sink/source behaviour along the sediment - tree stem - atmosphere continuum remains incomplete. Here, we applied stable isotope analysis (& #948 & sup& & /sup& C-CH& sub& & /sub& ) to gain insights into axial CH& sub& & /sub& transport and oxidation in two common and globally distributed subtropical lowland forest species (& em& Melaleuca quinquenervia& /em& and & em& Casuarina glauca& /em& ). We found consistent trends in CH& sub& & /sub& flux (decreasing with height) and & #948 & sup& & /sup& C-CH& sub& & /sub& enrichment (increasing with height) in relation to stem height from the ground. The average lower tree stem (0-40 cm) & #948 & sup& & /sup& C-CH& sub& & /sub& of & em& M. quinquenervia& /em& and & em& C. glauca& /em& flooded forests (-53.96 & #8240 and -65.89 & #8240 ) were similar to adjacent flooded sediment CH& sub& & /sub& ebullition (-52.87 & #8240 and -62.98 & #8240 ), suggesting that CH& sub& & /sub& is produced mainly via sedimentary sources. Upper stems (81-200 cm) displayed distinct & #948 & sup& & /sup& C-CH& sub& & /sub& enrichment (& em& M. quinquenervia& /em& -44.6 & #8240 and C. glauca -46.5 & #8240 respectively) compared to lower stems. Coupled 3D photogrammetry and novel 3D measurements on & em& M. quinquenervia& /em& revealed that distinct hotspots of CH& sub& & /sub& flux and isotopic fractionation were likely due to bark anomalies where preferential pathways of gas efflux were likely enhanced. By applying a& fractionation factor (derived from previous lab based tree stem bark experiments), diel experiments revealed greater & #948 & sup& & /sup& C-CH& sub& & /sub& enrichment and higher oxidation rates in the afternoon relative to the morning. Overall, we estimate CH& sub& & /sub& oxidation rates between the lower to upper stems across both species ranged from 1 to 69 % (average 33.1 & #177 3.4 %), representing a substantial tree-associated CH& sub& & /sub& sink occurring during axial transport.& &
Large methane emissions from tree stems complicate the wetland methane budget
Publisher: Authorea, Inc.
Date: 13-09-2023
Mangroves as a Source of Greenhouse Gases to the Atmosphere and Alkalinity and Dissolved Carbon to the Coastal Ocean: A Case Study from the Everglades National Park, Florida
Publisher: American Geophysical Union (AGU)
Date: 12-2020
DOI: 10.1029/2020JG005812
Assessing the recharge of a coastal aquifer using physical observations, tritium, groundwater chemistry and modelling
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.SCITOTENV.2016.11.181
Abstract: Assessing recharge is critical to understanding groundwater and preventing pollution. Here, we investigate recharge in an Australian coastal aquifer using a combination of physical, modelling and geochemical techniques. We assess whether recharge may occur through a pervasive layer of floodplain muds that was initially hypothesized to be impermeable. At least 59% of the precipitation volume could be accounted for in the shallow aquifer using the water table fluctuation method during four significant recharge events. Precipitation events 14% of annual precipitation). Tritium dating revealed long term net vertical recharge rates ranging from 27 to 114mm/year (average 58mm/year) which were interpreted as minimum net long term recharge. Borehole experiments revealed more permeable conditions and heterogeneous infiltration rates when the floodplain soils were dry. Wet conditions apparently expand floodplain clays, closing macropores and cracks that act as conduits for groundwater recharge. Modelled groundwater flow paths were consistent with tritium dating and provided independent evidence that the clay layer does not prevent local recharge. Overall, all lines of evidence demonstrated that the coastal floodplain muds do not prevent the infiltration of rainwater into the underlying sand aquifer, and that local recharge across the muds was widespread. Therefore, assuming fine-grained floodplain soils prevent recharge and protect underlying aquifers from pollution may not be reasonable.
Correction: An integrated approach for aquifer characterization and groundwater productivity evaluation in the Lake Haramaya watershed, Ethiopia
Publisher: Springer Science and Business Media LLC
Date: 30-04-2019
Radon-traced pore-water as a potential source of CO2 and CH4 to receding black and clear water environments in the Amazon Basin
Publisher: Wiley
Date: 07-08-2018
DOI: 10.1002/LOL2.10089
Abstract: Groundwater is a primary source of dissolved CO 2 and CH 4 in Amazonian headwaters, yet in higher order rivers, a groundwater ore‐water source is difficult to constrain due to the high spatial and temporal heterogeneity of pore‐water exchange. Here, we report coupled, high resolution measurements of p CO 2 , CH 4 , and 222 Rn (a natural pore‐water and groundwater tracer) during receding waters in the three major water types of the Central Amazon Basin: black (Negro River) clear (Tapajós River) white (Madeira River). Considerable spatial heterogeneity was observed in p CO 2 , CH 4 , and 222 Rn concentrations ranging from 460 μatm to 8030 μatm, 7 nM to 281 nM, and 713 dpm m −3 to 8516 dpm m −3 , respectively. The significant correlations between p CO 2 and CH 4 to 222 Rn in the black and clear waters suggests that pore‐water further enhanced CO 2 supersaturation by 18–47% and is a driver of CH 4 dynamics in these waters.
Seasonal, daily and diel N<sub>2</sub> effluxes in permeable carbonate sediments
Publisher: Copernicus GmbH
Date: 10-12-2012
Abstract: Abstract. Benthic metabolism and inorganic nitrogen and N2 flux rates (denitrification) were measured in permeable carbonate sands from Heron Island (Great Barrier Reef). Some of the N2 flux rates were among the highest measured in sediments. All benthic fluxes showed a significant difference between seasons with higher rates in summer and late summer. There was no distinct response of the benthic system to mass coral spawning. Instead, changes in benthic fluxes over 12 days in summer appears to be driven by tidal changes in water depth and associated changes in phytosynthetically active radiation reaching the sediments. Dark N2 fluxes were strongly correlated to benthic oxygen consumption across all sites and seasons (r2 = 0.64 p 0.005 slope = 0.036). However, there were seasonal differences with a steeper slope in summer than winter reflecting either more efficient coupling between respiration and nitrification-denitrification at higher temperatures or different sources of organic matter. Adding data from published studies on carbonate sands revealed two slopes in the dark N2 flux versus benthic oxygen consumption relationship. The lower slope (0.035) was most likely due to high carbon : nitrogen (C : N) organic matter from coral reefs, but competition by benthic microalgae for nitrogen, N-fixation or inefficient coupling between respiration and nitrification-denitrification can not be excluded. The steeper slope (0.089) was most likely due to respiration being driven by low C : N phyto-detritus. If the different slopes were driven by the sources of organic matter then global estimates of continental shelf denitrification are probably about right. In contrast, global estimates of continental shelf may be over-estimated if the low slope was due to inefficient coupling between respiration and nitrification-denitrification and also due to reduced N2 effluxes in the light associated with competition by benthic microalgae for nitrogen and N-fixation.
Pristine mangrove creek waters are a sink of nitrous oxide
Publisher: Springer Science and Business Media LLC
Date: 12-05-2018
DOI: 10.1038/SREP25701
Abstract: Nitrous oxide (N 2 O) is an important greenhouse gas, but large uncertainties remain in global budgets. Mangroves are thought to be a source of N 2 O to the atmosphere in spite of the limited available data. Here we report high resolution time series observations in pristine Australian mangroves along a broad latitudinal gradient to assess the potential role of mangroves in global N 2 O budgets. Surprisingly, five out of six creeks were under-saturated in dissolved N 2 O, demonstrating mangrove creek waters were a sink for atmospheric N 2 O. Air-water flux estimates showed an uptake of 1.52 ± 0.17 μmol m −2 d −1 , while an independent mass balance revealed an average sink of 1.05 ± 0.59 μmol m −2 d −1 . If these results can be upscaled to the global mangrove area, the N 2 O sink (~2.0 × 10 8 mol yr −1 ) would offset ~6% of the estimated global riverine N 2 O source. Our observations contrast previous estimates based on soil fluxes or mangrove waters influenced by upstream freshwater inputs. We suggest that the lack of available nitrogen in pristine mangroves favours N 2 O consumption. Widespread and growing coastal eutrophication may change mangrove waters from a sink to a source of N 2 O to the atmosphere, representing a positive feedback to climate change.
Mangroves as source of alkalinity and dissolved carbon to the coastal ocean: A case study from the Everglades National Park, Florida
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-101
Abstract: & & Most research evaluating the potential of mangroves as a sink for atmospheric carbon has focused on carbon burial. However, the few studies that have quantified lateral exchange of carbon and alkalinity, indicate that the dissolved carbon and alkalinity export may be several-fold more important than burial. This study aims to investigate rates and drivers of alkalinity, dissolved carbon and greenhouse gas fluxes of the mangrove-dominated Shark River estuary located in the Everglades National Park in Florida, USA. Time series and spatial surveys were conducted to asses total alkalinity (TAlk), organic alkalinity (OAlk), dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), carbon dioxide (CO& sub& & /sub& ), methane (CH& sub& & /sub& ) and nitrous oxide (N& sub& & /sub& O). Dominant metabolic processes driving dissolved carbon and greenhouse gas dynamics varied along the estuary salinity gradient. Dissolved carbon and greenhouse gas concentrations were strongly coupled to porewater input, which was examined using Rn-222. Shark River was a source of CO& sub& & /sub& (92 mmol/m& sup& & #173 & /sup& /d), CH& sub& & /sub& (60 & #181 mol/m& sup& & #173 & /sup& /d) and N& sub& & /sub& O (2 & #181 mol/m& #173 & sup& & /sup& /d) to the atmosphere. Dissolved carbon export (DIC = 142 mmol/m& #173 & sup& & /sup& /d, DOC = 39 mmol/m& #173 & sup& & /sup& /d) was several-fold higher than burial (~28 mmol/m& sup& & /sup& /d) and represents an additional carbon sink. Furthermore, the estuary was a source of TAlk (97 mmol/m& #173 & sup& & /sup& /d) to the coastal ocean, potentially buffering coastal acidification. Despite accounting for only a small share of TAlk, OAlk had a large effect on the estuarine pH. By integrating our results with previous studies, we argue that alkalinity, dissolved carbon and greenhouse gas fluxes should be considered in future blue carbon budgets.& &
Hypersaline tidal flats as important Blue Carbon systems: A case study from three ecosystems
Publisher: Copernicus GmbH
Date: 24-11-2020
DOI: 10.5194/BG-2020-426
Abstract: Abstract. Hypersaline tidal flats (HTFs) are coastal ecosystems with freshwater deficits often occurring in arid or semi-arid regions near mangrove supratidal zones with no major fluvial contributions. Here, we estimate that organic carbon (OC), total nitrogen (TN) and total phosphorus (TP) are being buried at rates averaging 21 (± 6), 1.7 (± 0.3), and 1.4 (± 0.3) g m−2 y−1, respectively, during the previous century in three contrasting HTFs systems, one in Brazil (eutrophic) and two in Australia (oligotrophic). Although these rates are lower than those from nearby mangrove, saltmarsh and seagrass systems, the importance of HTFs as sinks for OC, TN and TP may be significant given their extensive coverage. Despite the measured short-term variability between net air-saltpan CO2 influx and emission estimates found during the dry and wet season in the Brazilian HTF, the only site with seasonal CO2 fluxes measurements, the OC sedimentary profiles over several decades suggests efficient OC burial at all sites. Indeed, the stable isotopes of OC and TN (δ13C and δ15N) along with C : N ratios show that microphytobenthos are the major source of the buried OC in these HTFs. Our findings highlight a previously unquantified carbon as well as nutrient sink and suggest that coastal HTF ecosystems could be included in the emerging blue carbon framework.
Winter emissions of CO 2, CH 4, and N2O from temperate agricultural dams: fluxes, sources, and processes
Publisher: Wiley
Date: 11-2019
DOI: 10.1002/ECS2.2914
Bark-dwelling methanotrophic bacteria decrease methane emissions from trees
Publisher: Springer Science and Business Media LLC
Date: 09-04-2021
DOI: 10.1038/S41467-021-22333-7
Abstract: Tree stems are an important and unconstrained source of methane, yet it is uncertain whether internal microbial controls (i.e. methanotrophy) within tree bark may reduce methane emissions. Here we demonstrate that unique microbial communities dominated by methane-oxidising bacteria (MOB) dwell within bark of Melaleuca quinquenervia , a common, invasive and globally distributed lowland species. In laboratory incubations, methane-inoculated M. quinquenervia bark mediated methane consumption (up to 96.3 µmol m −2 bark d −1 ) and reveal distinct isotopic δ 13 C-CH 4 enrichment characteristic of MOB. Molecular analysis indicates unique microbial communities reside within the bark, with MOB primarily from the genus Methylomonas comprising up to 25 % of the total microbial community. Methanotroph abundance was linearly correlated to methane uptake rates (R 2 = 0.76, p = 0.006). Finally, field-based methane oxidation inhibition experiments demonstrate that bark-dwelling MOB reduce methane emissions by 36 ± 5 %. These multiple complementary lines of evidence indicate that bark-dwelling MOB represent a potentially significant methane sink, and an important frontier for further research.
Shifting nitrous oxide source/sink behaviour in a subtropical estuary revealed by automated time series observations
Publisher: Elsevier BV
Date: 07-2017
In-situ measurement on air–water flux of CH4, CO2 and their carbon stable isotope in lakes of northeast Tibetan Plateau
Publisher: Elsevier BV
Date: 04-2022
Structure and Function of Warm Temperate East Australian Coastal Lagoons
Publisher: CRC Press
Date: 15-06-2010
Drought, megafires and flood - climate extreme impacts on catchment-scale river water quality on Australia's east coast
Publisher: Elsevier BV
Date: 06-2022
DOI: 10.1016/J.WATRES.2022.118510
Abstract: Increased frequency and intensity of drought, wildfires and flooding due to climate change has major implications for river water quality, yet there are limited high-temporal resolution data capturing the combined transient impacts of these extreme events at large catchment scales. We present flow-stratified water quality data from a large coastal catchment (Macleay River, Australia) spanning severe drought and extensive fires followed by flooding. We examine concentrations (C), discharge (Q) and flux of suspended sediment, major ions, dissolved organic carbon (DOC) and key nutrients (NO
Low-Cost Nitric Oxide Sensors: Assessment of Temperature and Humidity Effects
Publisher: MDPI AG
Date: 21-11-2022
DOI: 10.3390/S22229013
Abstract: High equipment cost is a significant entry barrier to research for small organizations in developing solutions to air pollution problems. Low-cost electrochemical sensors show sensitivity at parts-per-billion by volume mixing ratios but are subject to variation due to changing environmental conditions, in particular temperature. In this study, we demonstrate a low-cost Internet of Things (IoT)-based sensor system for nitric oxide analysis. The sensor system used a four-electrode electrochemical sensor exposed to a series of isothermal/isohume conditions. When deployed under these conditions, stable baseline responses were achieved, in contrast to ambient air conditions where temperature and humidity conditions may be variable. The interrelationship between working and auxiliary electrodes was linear within an environmental envelope of 20–40 °C and 30–80% relative humidity, with correlation coefficients from 0.9980 to 0.9999 when measured under isothermal/isohume conditions. These data enabled the determination of surface functions that describe the working to auxiliary electrode offsets and calibration curve gradients and intercepts. The linear and reproducible nature of in idual calibration curves for stepwise nitric oxide (NO) additions under isothermal/isohume environments suggests the suitability of these sensors for applications aside from their role in air quality monitoring. Such applications would include nitric oxide kinetic studies for atmospheric applications or measurement of the potential biocatalytic activity of nitric oxide consuming enzymes in biocatalytic coatings, both of which currently employ high-capital-cost chemiluminescence detectors.
A seasonal source and sink of nitrous oxide in mangroves: Insights from concentration, isotope, and isotopomer measurements
Publisher: Elsevier BV
Date: 10-2018
Groundwater seepage as a driver of CO2 evasion in a coastal lake (Lake Ainsworth, NSW, Australia)
Publisher: Springer Science and Business Media LLC
Date: 10-02-2015
Groundwater as a source of dissolved organic matter to coastal waters: Insights from radon and CDOM observations in 12 shallow coastal systems
Publisher: Wiley
Date: 24-09-2019
DOI: 10.1002/LNO.11028
Carbon outwelling and emissions from two contrasting mangrove creeks during the monsoon storm season in Palau, Micronesia
Publisher: Elsevier BV
Date: 03-2019
Stable isotopes indicate ecosystem restructuring following climate‐driven mangrove dieback
Publisher: Wiley
Date: 10-12-2019
DOI: 10.1002/LNO.11387
Intermittently Closed and Open Lakes and/or Lagoons (ICOLLs) as groundwater-dominated coastal systems: Evidence from seasonal radon observations
Publisher: Elsevier BV
Date: 04-2016
Dissolved iron exports from an estuary surrounded by coastal wetlands: Can small estuaries be a significant source of Fe to the ocean?
Publisher: Elsevier BV
Date: 11-2015
Seasonal and Diurnal Dynamics of Atmospheric Radon, Carbon Dioxide, Methane, δ13C-CO2 and δ13C-CH4 in a Proposed Australian Coal Seam Gas Field
Publisher: Springer Science and Business Media LLC
Date: 25-09-2015
Seasonal exports and drivers of dissolved inorganic and organic carbon, carbon dioxide, methane and δ13C signatures in a subtropical river network
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.SCITOTENV.2016.09.020
Abstract: Riverine systems act as important aquatic conduits for carbon transportation between atmospheric, terrestrial and oceanic pools, yet the magnitude of these exports remain poorly constrained. Interconnected creek and river sites (n=28) were s led on a quarterly basis in three subcatchments of the subtropical Richmond River Catchment (Australia) to investigate spatial and temporal dynamics of dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), carbon dioxide (CO
The mangrove CO2 pump: Tidally driven pore‐water exchange
Publisher: Wiley
Date: 21-01-2021
DOI: 10.1002/LNO.11704
Greenhouse gases and submarine groundwater discharge in a Sydney Harbour embayment (Australia)
Publisher: Elsevier BV
Date: 07-2018
Land use drives nitrous oxide dynamics in estuaries on regional and global scales
Publisher: Wiley
Date: 24-02-2020
DOI: 10.1002/LNO.11426
Are methane emissions from mangrove stems a cryptic carbon loss pathway? Insights from a catastrophic forest mortality
Publisher: Wiley
Date: 20-07-2019
DOI: 10.1111/NPH.15995
Abstract: Growing evidence indicates that tree-stem methane (CH
Seasonal Variations in Dissolved Carbon Inventory and Fluxes in a Mangrove‐Dominated Estuary
Publisher: American Geophysical Union (AGU)
Date: 12-2020
DOI: 10.1029/2019GB006515
Abstract: Two experiments were performed during the wet and dry seasons to quantify dissolved carbon dynamics and fluxes in the Shark River, a tidal estuary flowing through the largest contiguous mangrove forest in North America (Everglades National Park, Florida, USA). During these experiments, between 80% and 87% of the total dissolved carbon pool consisted of inorganic carbon (DIC). Carbon inputs from mangroves to the estuary were slightly higher during the wet season, whereas alkalinity inputs were comparable during the two experiments. Longitudinal dissolved carbon fluxes to the coastal ocean were slightly higher during the wet season (13.53 ± 0.76 × 10 5 mol day −1 during the wet and 11.70 ± 0.32 × 10 5 mol day −1 during the dry), whereas longitudinal alkalinity flux was comparable during both experiments (10.64 ± 0.74 in the wet vs. 9.88 ± 0.30 × 10 5 mol day −1 during the dry season). Overall, DIC production in surface water, porewater, and groundwater was dominated by oxic mineralization of mangrove‐derived organic matter and carbonate dissolution. Carbonate dissolution was the most important alkalinity production process in the system. The experiments show that regardless of the season and hydro‐climatic conditions, Shark River receives large inputs of dissolved carbon from the upstream marsh, mangroves, and carbonate dissolution, and that per area, it exports a greater amount of dissolved carbon than many other mangrove‐dominated estuaries in the world.
Alkalinity Production Coupled to Pyrite FormationRepresents an Unaccounted Blue Carbon Sink
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-9592
Abstract: & & Blue carbon ecosystems, including mangroves, saltmarshes, and seagrasses, mitigate climate& br& change by storing atmospheric carbon. Previous blue carbon research has focused on organic carbon& br& stocks. However, recent studies suggest that lateral inorganic carbon export might be equally important.& br& Lateral export is a long-term carbon sink if carbon is exported as alkalinity (TAlk) produced via sulfate& br& reduction coupled to pyrite formation. This study evaluates drivers of pyrite formation in blue carbon& br& ecosystems, compares pyrite production to TAlk outwelling rates, and estimates global pyrite stocks in& br& mangroves. We quantified pyrite stocks in mangroves, saltmarshes, and seagrasses along a latitudinal& br& gradient on the Australian East Coast, including a mangrove dieback area, and in the Everglades& br& (Florida, USA). Our results indicate that pyrite stocks were driven by a combination of biomass, tidal& br& litude, sediment organic carbon, sediment accumulation rates, rainfall, latitude, temperature, and& br& iron availability. Pyrite stocks were three-times higher in mangroves (103 & #177 61 Mg/ha) than in saltmarshes& br& (30 & #177 30 Mg/ha) and seagrasses (32 & #177 1 Mg/ha). Mangrove pyrite stocks were linearly correlated to& br& TAlk export at sites where sulfate reduction was the dominant TAlk producing process. However, pyrite& br& generation could not explain all TAlk outwelling. We present the first global model estimating pyrite& br& stocks in mangroves, giving a first-order estimate of 197 Mg/ha (RMSE = 24 Mg/ha). In mangroves,& br& estimated global TAlk production coupled to pyrite formation (& #8764 mol/m& sup& & /sup& /y) is equal to & #8764 % of their& br& global carbon burial rate, highlighting the importance of including TAlk export in future blue carbon& br& budgets.& &
Groundwater, Acid and Carbon Dioxide Dynamics Along a Coastal Wetland, Lake and Estuary Continuum
Publisher: Springer Science and Business Media LLC
Date: 25-04-2016
Metabolism of different benthic habitats and their contribution to the carbon budget of a shallow oligotrophic sub-tropical coastal system (southern Moreton Bay, Australia)
Publisher: Springer Science and Business Media LLC
Date: 19-03-2010
Determining coral reef calcification and primary production using automated alkalinity, pH and pCO measurements at high temporal resolution
Publisher: Elsevier BV
Date: 09-2018
Rainfall drives rapid shifts in carbon and nutrient source-sink dynamics of an urbanised, mangrove-fringed estuary
Publisher: Elsevier BV
Date: 02-2021
Differences in benthic metabolism, nutrient fluxes, and denitrification in Caulerpa taxifolia communities compared to uninvaded bare sediment and seagrass (Zostera capricorni ) habitats
Publisher: Wiley
Date: 27-08-2011
Net Drawdown of Greenhouse Gases (CO2, CH4 and N2O) by a Temperate Australian Seagrass Meadow
Publisher: Springer Science and Business Media LLC
Date: 17-03-2022
DOI: 10.1007/S12237-022-01068-8
Abstract: Seagrasses have some of the highest rates of carbon burial on the planet and have therefore been highlighted as ecosystems for nature-based climate change mitigation. However, information is still needed on the net radiative forcing benefit of seagrasses inclusive of their associated greenhouse gas (GHG) emissions. Here, we report simultaneous estimates of seagrass-associated carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) air–water emissions. Applying in situ s ling within a south-east Australian seagrass ecosystem, this study finds atmospheric GHG emissions from waters above seagrasses to range from − 480 ± 15.96 to − 16.2 ± 8.32 mg CO 2 -equivalents m 2 d −1 (net uptake), with large temporal and spatial variability. Using a combination of gas specific mass balance equations, dissolved stable carbon isotope values ( δ 13 C) and in situ time-series data, CO 2 -e flux is estimated at − 21.74 mg m 2 d −1 . We find that the net release of CH 4 (0.44 µmol m 2 h −1 ) and net uptake of N 2 O (− 0.06 µmol m 2 h −1 ) effectively negated each other at 16.12 and − 16.13 mg CO 2 -e m 2 d −1 , respectively. The results of this study indicate that temperate Australian seagrasses may function as net sinks of atmospheric CO 2 -e. These results contribute towards filling key emission accounting gaps both in the Australian region, and through the simultaneous measurement of the three key greenhouse gas species.
Large methane emission during ice-melt in spring from thermokarst lakes and ponds in the interior Tibetan Plateau
Publisher: Elsevier BV
Date: 11-2023
The tidal freshwater river zone: Physical properties and biogeochemical contribution to estuarine hypoxia and acidification - The “hydrologic switch”
Publisher: Elsevier BV
Date: 05-2022
Submarine groundwater discharge drives nitrous oxide source/sink dynamics in a metropolitan estuary
Publisher: Wiley
Date: 15-02-2021
DOI: 10.1002/LNO.11710
Supplementary material to "Stable isotopes track the ecological and biogeochemical legacy of mass mangrove forest dieback in the Gulf of Carpentaria, Australia"
Publisher: Copernicus GmbH
Date: 02-03-2020
Wetland methane emissions dominated by plant-mediated fluxes: Contrasting emissions pathways and seasons within a shallow freshwater subtropical wetland
Publisher: Wiley
Date: 13-03-2019
DOI: 10.1002/LNO.11158
Terrestrial versus aquatic carbon fluxes in a subtropical agricultural floodplain over an annual cycle
Publisher: Elsevier BV
Date: 10-2018
Seasonal, daily and diel N<sub>2</sub> effluxes in permeable carbonate sediments
Publisher: Copernicus GmbH
Date: 18-04-2013
Abstract: Abstract. Benthic metabolism and inorganic nitrogen and N2 flux rates (denitrification) were measured in permeable carbonate sands from Heron Island (Great Barrier Reef). Some of the N2 flux rates were among the highest measured in sediments. All benthic fluxes showed a significant difference between seasons with higher rates in summer and late summer. There was no distinct response of the benthic system to mass coral spawning. Instead, changes in benthic fluxes over 12 days in summer appear to be driven by tidal changes in water depth and associated changes in phytosynthetically active radiation reaching the sediments. Dark N2 fluxes were strongly correlated to benthic oxygen consumption across all sites and seasons (r2 = 0.63 p 0.005 slope = 0.035). However, there were seasonal differences with a steeper slope in summer than winter, reflecting either more efficient coupling between respiration and nitrification–denitrification at higher temperatures or different sources of organic matter. Adding data from published studies on carbonate sands revealed two slopes in the dark N2 flux versus benthic oxygen consumption relationship. The lower slope (0.035) was most likely due to high carbon : nitrogen (C : N) organic matter from coral reefs, and associated assimilation of nitrogen by heterotrophic bacteria including enhanced heterotrophic N-fixation, but competition by benthic microalgae or inefficient coupling between respiration and nitrification–denitrification cannot be excluded. The steeper slope (0.089) was most likely due to respiration being driven by low C : N phytodetritus. If the different slopes were driven by the sources of organic matter, then global estimates of continental shelf denitrification are probably about right. In contrast, global estimates of continental shelf denitrification may be over-estimated if the low slope was due to inefficient coupling between respiration and nitrification–denitrification and also due to reduced N2 effluxes in the light associated with competition by benthic microalgae for nitrogen and N-fixation.
Coupling Automated Radon and Carbon Dioxide Measurements in Coastal Waters
Publisher: American Chemical Society (ACS)
Date: 25-06-2012
DOI: 10.1021/ES301961B
Abstract: Groundwater discharge could be a major, but as yet poorly constrained, source of carbon dioxide to lakes, wetlands, rivers, estuaries, and coastal waters. We demonstrate how coupled radon ((222)Rn, a natural groundwater tracer) and pCO(2) measurements in water can be easily performed using commercially available gas analysers. Portable, automated radon and pCO(2) gas analysers were connected in series and a closed air loop was established with gas equilibration devices (GED). We experimentally assessed the advantages and disadvantages of six GED. Response times shorter than 30 min for (222)Rn and 5 min for pCO(2) were achieved. Field trials revealed significant positive correlations between (222)Rn and pCO(2) in estuarine waterways and in a mangrove tidal creek, implying that submarine groundwater discharge was a source of CO(2) to surface water. The described system can provide high resolution, high precision concentrations of both radon and pCO(2) with nearly no additional effort compared to measuring only one of these gases. Coupling automated (222)Rn and pCO(2) measurements can provide new insights into how groundwater seepage contributes to aquatic carbon budgets.
Spatial and temporal variability of carbon dioxide and methane fluxes over semi-diurnal and spring–neap–spring timescales in a mangrove creek
Publisher: Elsevier BV
Date: 02-2015
Submarine Groundwater Discharge Exceeds River Inputs as a Source of Nutrients to the Great Barrier Reef
Publisher: American Chemical Society (ACS)
Date: 08-10-2023
Isotopic evidence for axial tree stem methane oxidation within subtropical lowland forests
Publisher: Wiley
Date: 12-04-2021
DOI: 10.1111/NPH.17343
Abstract: Knowledge regarding mechanisms moderating methane (CH 4 ) sink/source behaviour along the soil–tree stem–atmosphere continuum remains incomplete. Here, we applied stable isotope analysis (δ 13 C‐CH 4 ) to gain insights into axial CH 4 transport and oxidation in two globally distributed subtropical lowland species ( Melaleuca quinquenervia and Casuarina glauca ). We found consistent trends in CH 4 flux (decreasing with height) and δ 13 C‐CH 4 enrichment (increasing with height) in relation to stem height from ground. The average lower tree stem δ 13 C‐CH 4 (0–40 cm) of Melaleuca and Casuarina (−53.96‰ and −65.89‰) were similar to adjacent flooded soil CH 4 ebullition (−52.87‰ and −62.98‰), suggesting that stem CH 4 is derived mainly by soil sources. Upper stems (81–200 cm) displayed distinct δ 13 C‐CH 4 enrichment ( Melaleuca −44.6‰ and Casuarina −46.5‰, respectively). Coupled 3D‐photogrammetry with novel 3D‐stem measurements revealed distinct hotspots of CH 4 flux and isotopic fractionation on Melaleuca , which were likely due to bark anomalies in which preferential pathways of gas efflux were enhanced. Diel experiments revealed greater δ 13 C‐CH 4 enrichment and higher oxidation rates in the afternoon, compared with the morning. Overall, we estimated that c . 33% of the methane was oxidised between lower and upper stems during axial transport, therefore potentially representing a globally significant, yet previously unaccounted for, methane sink.
Supplementary material to "TECHNICAL NOTE: Coupling infrared gas analysis and cavity ring down spectroscopy for autonomous, high temporal resolution measurements of DIC and δ<sup&g
Publisher: Copernicus GmbH
Date: 22-11-2016
Blue carbon oxidation revealed by radiogenic and stable isotopes in a mangrove system
Publisher: American Geophysical Union (AGU)
Date: 27-05-2017
DOI: 10.1002/2017GL073753
Seasonal Drivers of Carbon Dioxide Dynamics in a Hydrologically Modified Subtropical Tidal River and Estuary (Caboolture River, Australia)
Publisher: American Geophysical Union (AGU)
Date: 06-2018
DOI: 10.1029/2017JG004023
Radium-derived porewater exchange and dissolved N and P fluxes in mangroves
Publisher: Elsevier BV
Date: 03-2017
The Interplay Between Dimethyl Sulfide (DMS) and Methane (CH4) in a Coral Reef Ecosystem
Publisher: Frontiers Media SA
Date: 20-06-2022
DOI: 10.3389/FMARS.2022.910441
Abstract: Earth’s Radiation Budget is partly dictated by the fragile and complex balance between biogenic volatile organic compounds (BVOCs) and greenhouse gases (GHGs), which have the potential to impose cooling or warming once emitted to the atmosphere. Whilst methane (CH 4 ) is strictly associated with global warming due to its solar-radiation absorbing properties, dimethyl sulfide (DMS) is generally considered a cooling gas through the light scattering properties of its atmospheric oxidation products. However, DMS may also partially contribute to the Earth’s warming through a small portion of it being degraded to CH 4 in the water column. Coral reefs emit both DMS and CH 4 but they have not previously been simultaneously measured. Here, we report DMS and CH 4 fluxes as well as aerosol particle counts at Heron Island, southern Great Barrier Reef, during the austral summer of 2016. Sea-to-air DMS and CH 4 fluxes were on average 24.9 ± 1.81 and 1.36 ± 0.11 µmol m -2 d -1 , whilst intermediate (& 0.5-2.5 um) and large (& 2.5 um) particle number concentrations averaged 5.51 x 10 6 ± 1.73 x 10 5 m -3 and 1.15 x 10 6 ± 4.63 x 10 4 m -3 , respectively. Positive correlations were found between DMS emissions and the abundance of intermediate (R 2 = 0.1669, p & 0.001, n = 93) and large (R 2 = 0.0869, p = 0.004, n = 93) aerosol particles, suggesting that DMS sea-to-air emissions significantly contribute to the growth of existing particles to the measured size ranges at the Heron Island lagoon. Additionally, a strong positive correlation was found between DMS and CH 4 fluxes (R 2 = 0.7526, p & 0.00001, n = 93), suggesting that the emission of these volatile compounds from coral reefs is closely linked. The slope of the regression between DMS and CH 4 suggests that CH 4 emissions at the Heron Island lagoon represent 5% of that of DMS, which is consistent with the average sea-to-air fluxes reported in this study (i.e. 24.9 ± 1.81 µmol m -2 d -1 for DMS and 1.36 ± 0.11 for CH 4 ). These findings provide new insights on the complexity of BVOC and GHG emissions in coral reef systems and their potential role in climate regulation.
Carbon dioxide dynamics in a tropical estuary over seasonal and rain-event time scales
Publisher: Elsevier BV
Date: 12-2020
Commentary: Evaluating the Role of Seagrass in Cenozoic CO2 Variations
Publisher: Frontiers Media SA
Date: 29-08-2017
Carbon dioxide hydrodynamics along a wetland-lake-stream-waterfall continuum (Blue Mountains, Australia)
Publisher: Elsevier BV
Date: 07-2021
Groundwater methane in a potential coal seam gas extraction region
Publisher: Elsevier BV
Date: 09-2015
Methanogens limited to lower rhizosphere and to an atypical salt marsh niche along a pristine intertidal mangrove continuum
Publisher: Wiley
Date: 22-08-2023
DOI: 10.1002/LNO.12414
Abstract: Mangroves are valuable ecosystems that facilitate primary production, carbon sequestration, and regulation of greenhouse gas (GHG) cycles in coastal sediments, with microorganisms playing key roles. Specialized bacteria and archaea compete for energy and resources in mangrove sediments to inhabit optimal ecological niches and can produce or consume methane (CH 4 )—a potent GHG—in the process. CH 4 cycling in mangroves has gained growing attention, yet uncertainties regarding functional and spatial distributions of microorganisms remain. Here, we demonstrate that in a pristine mangrove forest, CH 4 concentrations and methanogen communities are concentrated within lower or below rhizosphere depths. We also reveal atypical niches for methanogens in the upper tidal salt marsh zone where vegetation is sparse and highest methanogens abundances were detected at deepest depths (4715 reads g −1 ) despite relatively high redox potentials ( 250 mV). Pore water CH 4 concentrations were highest at the deepest depth within the mangrove forest (max. 3.40 ± 0.21 μ M) and coincided with the highest sediment CH 4 fluxes (276.4 ± 54.2 μ mol m −2 d −1 ) and methanotroph abundances at the surface (1309 reads g −1 ). Sediment CH 4 oxidation fractions between the deepest (60 cm) and shallowest (5 cm) depths were estimated between 18.8% and 64.9%. Positive correlation between crab burrows and CH 4 fluxes suggests that CH 4 from deeper sediment and salt marsh niches can be transported via conduits to the atmosphere. The spatial data from this study highlights the importance of investigating CH 4 dynamics across estuarine ecosystem gradients to better understand the complex roles of vital coastal vegetation zones in the face of a changing climate.
How important are annual tree stem methane emissions to the total wetland flux? A seasonal case study of subtropical lowland Melaleuca forest.
Publisher: Copernicus GmbH
Date: 27-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-3300
Abstract: & & Tree stem methane emissions are gaining rapid research momentum, with about one-third of all literature in this field published in 2021 alone. Long term and seasonal studies are currently rare, limiting our ability to constrain spatial and seasonal emissions variability, and to resolve the tree stem contribution to the total wetland methane flux i.e. soil, water and trees. Here we present preliminary methane flux data from a lowland & em& Melaleuca quinquenervia& /em& forest. We measured emissions & em& in situ& /em& along a ~3 m litude topo-gradient, encompassing forest in lower, transitional and upper elevation zones. Eight (ongoing) field c aigns at monthly intervals, captured flooded to dry to re-flooded site conditions. We measured the stem fluxes from 30 trees at four stem heights, along with 30 adjacent soil and water CH& sub& & /sub& fluxes. Ancillary parameters such as pore water (CH& sub& & /sub& , DO%, pH, temp, redox, EC), water table depth, and soil moisture (VWC %) were also measured. Tree stem fluxes ranged several orders of magnitude between hydrological seasons and topo-gradient zones (ranging from negligible to 17, 426 mmol ha& sup& -1& /sup& d& sup& -1& /sup& ). Soil fluxes were similar in litude and shifted from maximal CH& sub& & /sub& emissions during the wet conditions, to CH& sub& & /sub& uptake in dry locations. The importance of tree stem flux to the net ecosystem flux (NEF) differed between c aigns and hydrological zones, but were most substantial during flooded conditions and ranged from 36-75% of the NEF in the lower and transitional zones during peak emissions respectively. In the upper zone, the tree stem emissions offset the soil sink capacity by ~50% when the water table was closest to the soil surface. This study shows the importance of quantifying lowland tree stem CH& sub& & /sub& emissions to the total wetland flux. This data provides important baseline readings for southern hemisphere and Australian wetland forests, that generally experience dynamic rainfall and soil redox oscillations between flooding and droughts.& &
An integrated approach for aquifer characterization and groundwater productivity evaluation in the Lake Haramaya watershed, Ethiopia
Publisher: Springer Science and Business Media LLC
Date: 08-03-2019
Porewater exchange as a driver of carbon dynamics across a terrestrial-marine transect: Insights from coupled 222Rn and pCO2 observations in the German Wadden Sea
Publisher: Elsevier BV
Date: 04-2015
Benthic carbon metabolism in southeast Australian estuaries: habitat importance, driving forces, and application of artificial neural network models
Publisher: Inter-Research Science Center
Date: 20-10-2011
DOI: 10.3354/MEPS09336
Australian vegetated coastal ecosystems as global hotspots for climate change mitigation
Publisher: Springer Science and Business Media LLC
Date: 02-10-2019
DOI: 10.1038/S41467-019-12176-8
Abstract: Policies aiming to preserve vegetated coastal ecosystems (VCE tidal marshes, mangroves and seagrasses) to mitigate greenhouse gas emissions require national assessments of blue carbon resources. Here, we present organic carbon (C) storage in VCE across Australian climate regions and estimate potential annual CO 2 emission benefits of VCE conservation and restoration. Australia contributes 5–11% of the C stored in VCE globally (70–185 Tg C in aboveground biomass, and 1,055–1,540 Tg C in the upper 1 m of soils). Potential CO 2 emissions from current VCE losses are estimated at 2.1–3.1 Tg CO 2 -e yr -1 , increasing annual CO 2 emissions from land use change in Australia by 12–21%. This assessment, the most comprehensive for any nation to-date, demonstrates the potential of conservation and restoration of VCE to underpin national policy development for reducing greenhouse gas emissions.
Soil greenhouse gas fluxes from tropical coastal wetlands and alternative agricultural land uses
Publisher: Copernicus GmbH
Date: 16-09-2021
Abstract: Abstract. Coastal wetlands are essential for regulating the global carbon budget through soil carbon sequestration and greenhouse gas (GHG – CO2, CH4, and N2O) fluxes. The conversion of coastal wetlands to agricultural land alters these fluxes' magnitude and direction (uptake/release). However, the extent and drivers of change of GHG fluxes are still unknown for many tropical regions. We measured soil GHG fluxes from three natural coastal wetlands – mangroves, salt marsh, and freshwater tidal forests – and two alternative agricultural land uses – sugarcane farming and pastures for cattle grazing (ponded and dry conditions). We assessed variations throughout different climatic conditions (dry–cool, dry–hot, and wet–hot) within 2 years of measurements (2018–2020) in tropical Australia. The wet pasture had by far the highest CH4 emissions with 1231±386 mgm-2d-1, which were 200-fold higher than any other site. Dry pastures and sugarcane were the highest emitters of N2O with 55±9 mgm-2d-1 (wet–hot period) and 11±3 mgm-2d-1 (hot-dry period, coinciding with fertilisation), respectively. Dry pastures were also the highest emitters of CO2 with 20±1 gm-2d-1 (wet–hot period). The three coastal wetlands measured had lower emissions, with salt marsh uptake of -0.55±0.23 and -1.19±0.08 gm-2d-1 of N2O and CO2, respectively, during the dry–hot period. During the s led period, sugarcane and pastures had higher total cumulative soil GHG emissions (CH4+N2O) of 7142 and 56 124 CO2-eqkgha-1yr-1 compared to coastal wetlands with 144 to 884 CO2-eqkgha-1yr-1 (where CO2-eq is CO2 equivalent). Restoring unproductive sugarcane land or pastures (especially ponded ones) to coastal wetlands could provide significant GHG mitigation.
Diel coral reef acidification driven by porewater advection in permeable carbonate sands, Heron Island, Great Barrier Reef
Publisher: American Geophysical Union (AGU)
Date: 02-2011
DOI: 10.1029/2010GL046053
Bioturbator‐stimulated loss of seagrass sediment carbon stocks
Publisher: Wiley
Date: 27-09-2018
DOI: 10.1002/LNO.11044
Carbon budgets for three autotrophic Australian estuaries: Implications for global estimates of the coastal air‐water CO2 flux
Publisher: American Geophysical Union (AGU)
Date: 03-2012
DOI: 10.1029/2011GB004075
Greenhouse Gas Dynamics in a Salt-Wedge Estuary Revealed by High Resolution Cavity Ring-Down Spectroscopy Observations
Publisher: American Chemical Society (ACS)
Date: 22-11-2017
Groundwater Discharge as a Source of Dissolved Carbon and Greenhouse Gases in a Subtropical Estuary
Publisher: Springer Science and Business Media LLC
Date: 03-11-2016
Beyond burial: Lateral exchange is a significant atmospheric carbon sink in mangrove forests
Publisher: The Royal Society
Date: 07-2018
Abstract: The blue carbon paradigm has evolved in recognition of the high carbon storage and sequestration potential of mangrove, saltmarsh and seagrass ecosystems. However, fluxes of the potent greenhouse gases CH 4 and N 2 O, and lateral export of carbon are often overlooked within the blue carbon framework. Here, we show that the export of dissolved inorganic carbon (DIC) and alkalinity is approximately 1.7 times higher than burial as a long-term carbon sink in a subtropical mangrove system. Fluxes of methane offset burial by approximately 6%, while the nitrous oxide sink was approximately 0.5% of burial. Export of dissolved organic carbon and particulate organic carbon to the coastal zone is also significant and combined may account for an atmospheric carbon sink similar to burial. Our results indicate that the export of DIC and alkalinity results in a long-term atmospheric carbon sink and should be incorporated into the blue carbon paradigm when assessing the role of these habitats in sequestering carbon and mitigating climate change.
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