ORCID Profile
0000-0003-0524-842X
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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 | Chemical Oceanography | Inorganic Geochemistry | Environmental Chemistry (incl. Atmospheric Chemistry) | Surfacewater Hydrology | Environmental Science and Management | Oceanography | Ecosystem Function | Environmental Management | Carbon Sequestration Science | Environmental Sciences not elsewhere classified | Geochemistry not elsewhere classified | Hydrogeology | Soil Sciences | Ecology | Biological Oceanography | Organic Geochemistry | Marine and Estuarine Ecology (incl. Marine Ichthyology) | Other Chemical Sciences | Soil Chemistry (excl. Carbon Sequestration Science) | Land Capability and Soil Degradation | Fisheries Management | Natural Resource Management |
ANZSRC Socio-Economic Objective (SEO)
Ecosystem Assessment and Management of Coastal and Estuarine Environments | Coastal and Estuarine Water Management | Physical and Chemical Conditions of Water in Coastal and Estuarine Environments | Ecosystem Assessment and Management of Fresh, Ground and Surface Water Environments | Expanding Knowledge in the Environmental Sciences | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Climate Variability (excl. Social Impacts) | Coastal and Estuarine Soils | Physical and Chemical Conditions of Water in Fresh, Ground and Surface Water Environments (excl. Urban and Industrial Use) | Marine Flora, Fauna and Biodiversity | Ecosystem Adaptation to Climate Change | Coastal and Estuarine Land Management | Climate Change Mitigation Strategies | Economic Incentives for Environmental Protection | Climate Change Models | Integrated (ecosystem) assessment and management | Climate change | Physical and Chemical Conditions of Water in Marine Environments | Integrated (ecosystem) assessment and management | Remnant Vegetation and Protected Conservation Areas in Coastal and Estuarine Environments | Climate and Climate Change not elsewhere classified | Expanding Knowledge in the Earth Sciences | Ecosystem Assessment and Management of Marine Environments | Rights to Environmental and Natural Resources (excl. Water Allocation)
Related Links
Publications
Surface Water and Groundwater Interactions in Salt Marshes and Their Impact on Plant Ecology and Coastal Biogeochemistry
Publisher: American Geophysical Union (AGU)
Date: 15-02-2022
DOI: 10.1029/2021RG000740
Abstract: Salt marshes are highly productive intertidal wetlands providing important ecological services for maintaining coastal bio ersity, buffering against oceanic storms, and acting as efficient carbon sinks. However, about half of these wetlands have been lost globally due to human activities and climate change. Inundated periodically by tidal water, salt marshes are subjected to strong surface water and groundwater interactions, which affect marsh plant growth and biogeochemical exchange with coastal water. This paper reviews the state of knowledge and current approaches to quantifying marsh surface water and groundwater interactions with a focus on porewater flow and associated soil conditions in connection with plant zonation as well as carbon, nutrients, and greenhouse gas fluxes. Porewater flow and solute transport in salt marshes are primarily driven by tides with moderate regulation by rainfall, evapotranspiration and sea level rise. Tidal fluctuations play a key role in plant zonation through alteration of soil aeration and salt transport, and drive the export of significant fluxes of carbon and nutrients to coastal water. Despite recent progress, major knowledge gaps remain. Previous studies focused on flows in creek‐perpendicular marsh sections and overlooked multi‐scale 3D behaviors. Understanding of marsh ecological‐hydrological links under combined influences of different forcing factors and boundary disturbances is lacking. Variations of surface water and groundwater temperatures affect porewater flow, soil conditions and biogeochemical exchanges, but the extent and underlying mechanisms remain unknown. We need to fill these knowledge gaps to advance understanding of salt marshes and thus enhance our ability to protect and restore them.
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
Whale carcass scavenging by sharks
Publisher: Elsevier BV
Date: 07-2019
The renaissance of Odum's outwelling hypothesis in 'Blue Carbon' science
Publisher: Elsevier BV
Date: 07-2021
Land use and episodic rainfall as drivers of nitrogen exports in subtropical rivers: Insights from δ15N-NO3 −, δ18O-NO3 − and 222Rn
Publisher: Elsevier BV
Date: 03-2021
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.
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.
The spatial and temporal drivers of pCO2, pCH4 and gas transfer velocity within a subtropical estuary.
Publisher: Elsevier BV
Date: 08-2018
Contrasting mercury and manganese deposition in a mangrove-dominated estuary (Guaratuba Bay, Brazil)
Publisher: Springer Science and Business Media LLC
Date: 30-04-2008
Mangrove mortality in a changing climate: An overview
Publisher: Elsevier BV
Date: 12-2018
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
The “salt wedge pump”: Convection-driven pore-water exchange as a source of dissolved organic and inorganic carbon and nitrogen to an estuary
Publisher: Wiley
Date: 21-08-2012
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
Global carbon dioxide efflux from rivers enhanced by high nocturnal emissions
Publisher: Springer Science and Business Media LLC
Date: 15-04-2021
A new conceptual framework for the transformation of groundwater dissolved organic matter
Publisher: Springer Science and Business Media LLC
Date: 20-04-2022
DOI: 10.1038/S41467-022-29711-9
Abstract: Groundwater comprises 95% of the liquid fresh water on Earth and contains a erse mix of dissolved organic matter (DOM) molecules which play a significant role in the global carbon cycle. Currently, the storage times and degradation pathways of groundwater DOM are unclear, preventing an accurate estimate of groundwater carbon sources and sinks for global carbon budgets. Here we reveal the transformations of DOM in aging groundwater using ultra-high resolution mass spectrometry combined with radiocarbon dating. Long-term anoxia and a lack of photodegradation leads to the removal of oxidised DOM and a build-up of both reduced photodegradable formulae and aerobically biolabile formulae with a strong microbial signal. This contrasts with the degradation pathway of DOM in oxic marine, river, and lake systems. Our findings suggest that processes such as groundwater extraction and subterranean groundwater discharge to oceans could result in up to 13 Tg of highly photolabile and aerobically biolabile groundwater dissolved organic carbon released to surface environments per year, where it can be rapidly degraded. These findings highlight the importance of considering groundwater DOM in global carbon budgets.
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
Carbon sequestration in aquatic ecosystems: Recent advances and challenges
Publisher: Wiley
Date: 11-2022
DOI: 10.1002/LNO.12268
Taking the metabolic pulse of the world's coral reefs
Publisher: Public Library of Science (PLoS)
Date: 09-01-2018
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
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
Heavy metal contamination in coastal sediments and soils near the Brazilian Antarctic Station, King George Island
Publisher: Elsevier BV
Date: 02-2005
DOI: 10.1016/J.MARPOLBUL.2004.10.009
Abstract: This paper investigates the natural and anthropogenic processes controlling sediment chemistry in Admiralty Bay, King George Island, Antarctica, emphasizing the area affected by the Brazilian Antarctic Station Comandante Ferraz (Ferraz). Total and bioavailable concentrations of sixteen elements were determined in 32 sediment and 14 soils s les. Factor analysis allowed us to distinguish three groups of s les: (1) Ferraz sediments, with higher content of total trace metals and organic matter (2) control sediments, with intermediate characteristics (3) Ferraz soils, with higher bioavailability of most metals due to its oxidizing condition and low organic matter content. Major elements such as Fe, Al, Ca and Ti presented similar levels in all three groups. Enrichment factor calculations showed that paints, sewage and petroleum contamination enhanced metal concentrations in Ferraz surface sediments as follows: B, Mo, and Pb (>90%) V and Zn (70-80%) Ni, Cu, Mg, and Mn (30-40%). Despite evidence of contamination in these sediments, the low bioavailability, probably caused by iron-sulfide, indicates small environmental risks.
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
Radium tracing nutrient inputs through submarine groundwater discharge in the global ocean
Publisher: Springer Science and Business Media LLC
Date: 05-02-2018
DOI: 10.1038/S41598-018-20806-2
Abstract: Riverine and atmospheric inputs are often considered as the main terrestrial sources of dissolved inorganic nitrogen (DIN), phosphorus (DIP), and silicon (DSi) in the ocean. However, the fluxes of nutrients via submarine groundwater discharge (SGD) often exceed riverine inputs in different local and regional scale settings. In this study, we provide a first approximation of global nutrient fluxes to the ocean via total SGD, including pore water fluxes, by combining a global compilation of nutrient concentrations in groundwater and the SGD-derived 228 Ra fluxes. In order to avoid overestimations in calculating SGD - derived nutrient fluxes, the endmember value of nutrients in global groundwater was chosen from saline groundwater s les (salinity ) which showed relatively lower values over all regions. The results show that the total SGD-derived fluxes of DIN, DIP, and DSi could be approximately 1.4-, 1.6-, and 0.7-fold of the river fluxes to the global ocean (Indo-Pacific and Atlantic Oceans), respectively. Although significant portions of these SGD-derived nutrient fluxes are thought to be recycled within sediment-aquifer systems over various timescales, SGD-derived nutrient fluxes should be included in the global ocean budget in order to better understand dynamic interactions at the land-ocean interface.
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.
Whale carcass strandings on beaches: Management challenges, research needs, and examples from Australia
Publisher: Elsevier BV
Date: 09-2018
Submarine groundwater discharge impacts on coastal nutrient biogeochemistry
Publisher: Springer Science and Business Media LLC
Date: 30-03-2021
Anthropogenic land use substantially increases riverine CO2 emissions
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.JES.2021.12.040
Abstract: Carbon dioxide (CO
White shark behaviour altered by stranded whale carcasses: Insights from drones and implications for beach management
Publisher: Elsevier BV
Date: 02-2021
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
Linking riverine partial pressure of carbon dioxide to dissolved organic matter optical properties in a Dry-hot Valley Region
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.SCITOTENV.2019.135353
Abstract: The mineralization of dissolved organic matter (DOM) can partially explain riverine carbon dioxide (CO
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
Anthropogenic nitrate attenuation versus nitrous oxide release from a woodchip bioreactor
Publisher: Elsevier BV
Date: 05-2022
DOI: 10.1016/J.ENVPOL.2022.118814
Abstract: Nitrogen loss via overland flow from agricultural land use is a global threat to waterways. On-farm denitrifying woodchip bioreactors can mitigate NO
Alkalinity export to the ocean is a major carbon sequestration mechanism in a macrotidal saltmarsh
Publisher: Wiley
Date: 13-06-2022
DOI: 10.1002/LNO.12155
Abstract: Saltmarshes are a blue carbon ecosystem accumulating large quantities of organic carbon in sediments. Some of this carbon can be transformed into dissolved inorganic carbon (DIC) and methane (CH 4 ) that may eventually be exported to the ocean or atmosphere. Although extensive studies have quantified specific components of the carbon budget such as carbon burial, limited attention has been given to pore‐water‐derived carbon and total alkalinity (TA) exports to the ocean. Here, we quantified lateral exports to the ocean (outwelling) of 202 ± 160 and 78 ± 75 mmol m −2 d −1 of DIC and TA, respectively. The TA : DIC concentration ratio in the creek waters was ~ 1, implying TA production from anaerobic mineralization in sediments. The lateral TA exports were comparable to the local (94 ± 48 mmol m −2 d −1 ) and national (~ 50 mmol m −2 d −1 ) organic carbon burial. High TA exports could locally increase the ocean buffering capacity and contribute bicarbonate to the coastal ocean, acting as a long‐term carbon storage. Pore water traced by radon contributed 28–37% and 58–69% of DIC and TA exports. Separating the two major DIC components (i.e., CO 2 emissions and alkalinity exports) is essential to resolve the carbon sequestration potential from saltmarshes. Here, dissolved CO 2 emissions to the atmosphere accounted for 3–5% of total DIC outwelling. CH 4 emissions played a minor role offsetting around 0.3 to 6% of the carbon sequestration. Overall, we demonstrate that alkalinity export into the ocean can be an overlooked carbon sequestration pathway in saltmarshes at rates comparable to carbon burial.
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 and alkalinity outwelling across the groundwater-creek-shelf continuum off Amazonian mangroves
Publisher: Wiley
Date: 23-09-2021
DOI: 10.1002/LOL2.10210
Abstract: Lateral fluxes (i.e., outwelling) of dissolved organic (DOC) and inorganic (DIC) carbon and total alkalinity were estimated using radium isotopes at the groundwater, mangrove creek, and continental shelf scales in the Amazon region. Observations of salinity and radium isotopes in the creek indicated tidally driven groundwater exchange as the main source of carbon. Radium‐derived transport rates indicate that mangrove carbon is exported out of the continental shelf on timescales of 22 ± 7 d. Bicarbonate was the main form (82% ± 11%) of total dissolved carbon in all s les, followed by DOC (13% ± 12%) and CO 2 (5% ± 4%). DIC (18.7 ± 15.7 mmol m −2 d −1 ) exceeded DOC (3.0 ± 4.1 mmol m −2 d −1 ) outwelling at all spatial scales. The interpretation of outwelling across the mangrove‐ocean continuum is related to the spatial and temporal scales investigated. At all scales, outwelling represented a major coastal carbon pathway driving bicarbonate storage in the ocean.
Carbon dioxide dynamics driven by groundwater discharge in a coastal floodplain creek
Publisher: Elsevier BV
Date: 06-2013
Uranium export from a sandy beach subterranean estuary in Australia
Publisher: Elsevier BV
Date: 11-2017
Elevated concentrations of dissolved Ba, Fe and Mn in a mangrove subterranean estuary: Consequence of sea level rise?
Publisher: Elsevier BV
Date: 07-2012
Methane Emissions in Seagrass Meadows as a Small Offset to Carbon Sequestration
Publisher: American Geophysical Union (AGU)
Date: 26-05-2023
DOI: 10.1029/2022JG007295
Abstract: Seagrass meadows are effective carbon sinks due to high primary production and sequestration in sediments. However, methane (CH 4 ) emissions can partially counteract their carbon sink capacity. Here, we measured diffusive sediment‐water and sea‐air CO 2 and CH 4 fluxes in a coastal embayment dominated by Posidonia oceanica in the Mediterranean Sea. High‐resolution timeseries observations revealed large spatial and temporal variability in CH 4 concentrations (2–36 nM). Lower sea‐air CH 4 emissions were observed in an area with dense seagrass meadows compared to patchy seagrass. A 6%−40% decrease of CH 4 concentration in the surface water around noon indicates that photosynthesis likely limits CH 4 fluxes. Sediments were the major CH 4 source as implied from radon (a natural porewater tracer) observations and evidence for methanogenesis in deeper sediments. CH 4 sediment‐water fluxes (0.1 ± 0.1–0.4 ± 0.1 μmol m −2 d −1 ) were higher than average sea‐air CH 4 emissions (0.12 ± 0.10 μmol m −2 d −1 ), suggesting that dilution and CH 4 oxidation in the water column could reduce net CH 4 fluxes into the atmosphere. Overall, relatively low sea‐air CH 4 fluxes likely represent the net emissions from subtidal seagrass habitat not influenced by allochthonous CH 4 sources. The local CH 4 emissions in P. oceanica can offset less than 1% of the carbon burial in sediments (142 ± 69 g CO 2eq m −2 yr −1 ). Combining our results with earlier observations in other seagrass meadows worldwide reveals that global CH 4 emissions only offset a small fraction ( %) of carbon sequestration in sediments from seagrass meadows.
Mapping groundwater discharge to a coastal lagoon using combined spatial airborne thermal imaging, radon (222Rn) and multiple physicochemical variables
Publisher: Wiley
Date: 14-09-2020
DOI: 10.1002/HYP.13903
Baseline mercury and zinc concentrations in terrestrial and coastal organisms of Admiralty Bay, Antarctica
Publisher: Elsevier BV
Date: 03-2006
DOI: 10.1016/J.ENVPOL.2005.07.007
Abstract: This paper provides the first quantitative information on mercury in soil, coastal sediment, and in characteristic organisms of terrestrial and shallow coastal marine ecosystems from Admiralty Bay (King George Island, Antarctica). As expected for a remote area, mercury content is low in abiotic components of the ecosystem, and probably similar to natural levels. Mercury also occurs in very low concentrations in the vegetation, invertebrates and fish. These low mercury levels may be due to sulphide formation in reducing sediments of this environment. Higher concentrations of mercury occurred in bird feathers and mammal hair, indicating biomagnification. This was not found for Zinc. These results may be useful as a reference background to detect future inputs of trace elements in this remote area of the earth. Terrestrial vegetation and bird feathers are suggested as target regional biomonitors.
Heat transport dynamics at a sandy intertidal zone
Publisher: American Geophysical Union (AGU)
Date: 06-2013
DOI: 10.1002/WRCR.20325
Global coral reef ecosystems exhibit declining calcification and increasing primary productivity
Publisher: Springer Science and Business Media LLC
Date: 10-06-2021
DOI: 10.1038/S43247-021-00168-W
Abstract: Long-term coral reef resilience to multiple stressors depends on their ability to maintain positive calcification rates. Estimates of coral ecosystem calcification and organic productivity provide insight into the environmental drivers and temporal changes in reef condition. Here, we analyse global spatiotemporal trends and drivers of coral reef calcification using a meta-analysis of ecosystem-scale case studies. A linear mixed effects regression model was used to test whether ecosystem-scale calcification is related to seasonality, methodology, calcifier cover, year, depth, wave action, latitude, duration of data collection, coral reef state, Ω ar , temperature and organic productivity. Global ecosystem calcification estimated from changes in seawater carbonate chemistry was driven primarily by depth and benthic calcifier cover. Current and future declines in coral cover will significantly affect the global reef carbonate budget, even before considering the effects of sub-lethal stressors on calcification rates. Repeatedly studied reefs exhibited declining calcification of 4.3 ± 1.9% per year ( x̄ = 1.8 ± 0.7 mmol m −2 d −1 yr −1 ), and increasing organic productivity at 3.0 ± 0.8 mmol m −2 d −1 per year since 1970. Therefore, coral reef ecosystems are experiencing a shift in their essential metabolic processes of calcification and photosynthesis, and could become net dissolving worldwide around 2054.
Groundwater discharge rates and uncertainties in a coastal lagoon using a radon mass balance
Publisher: Elsevier BV
Date: 07-2021
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
Changes in organic carbon accumulation driven by mangrove expansion and deforestation in a New Zealand estuary
Publisher: Elsevier BV
Date: 06-2017
Global blue carbon accumulation in tidal wetlands increases with climate change
Publisher: Oxford University Press (OUP)
Date: 15-12-2020
DOI: 10.1093/NSR/NWAA296
Abstract: Coastal tidal wetlands produce and accumulate significant amounts of organic carbon (C) that help to mitigate climate change. However, previous data limitations have prevented a robust evaluation of the global rates and mechanisms driving C accumulation. Here, we go beyond recent soil C stock estimates to reveal global tidal wetland C accumulation and predict changes under relative sea level rise, temperature and precipitation. We use data from literature study sites and our new observations spanning wide latitudinal gradients and 20 countries. Globally, tidal wetlands accumulate 53.65 (95%CI: 48.52–59.01) Tg C yr−1, which is ∼30% of the organic C buried on the ocean floor. Modeling based on current climatic drivers and under projected emissions scenarios revealed a net increase in the global C accumulation by 2100. This rapid increase is driven by sea level rise in tidal marshes, and higher temperature and precipitation in mangroves. Countries with large areas of coastal wetlands, like Indonesia and Mexico, are more susceptible to tidal wetland C losses under climate change, while regions such as Australia, Brazil, the USA and China will experience a significant C accumulation increase under all projected scenarios.
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.
Recent 137Cs deposition in sediments of Admiralty Bay, Antarctica
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.JENVRAD.2010.02.006
Abstract: Cesium-137, radium-226 and lead-210 profiles of a 25 cm sediment core give an indication of recent changes in land-ocean interactions at a polar coastal environment (Admiralty Bay, King George Island, Antarctica). The linear sedimentation accumulation rate at the study site calculated from the unsupported (210)Pb profile was 6.7 mm/year from 1965 to 2005. A 3.5-fold increase in (137)Cs concentrations was observed in the top layer of this sediment core. This sharp increase seems to indicate a recent redistribution of fallout radionuclides previously deposited on soil, vegetation and snow. These results imply enhanced land-ocean interactions at this site likely as a result of climate change. Because our results are based on a single core, additional investigations are needed to confirm our observations.
Alkalinity of diverse water samples can be altered by mercury preservation and borosilicate vial storage
Publisher: Springer Science and Business Media LLC
Date: 11-05-2021
DOI: 10.1038/S41598-021-89110-W
Abstract: We compared the effects of preservation and storage methods on total alkalinity (A T ) of seawater, estuarine water, freshwater, and groundwater s les stored for 0 – 6 months. Water s les, untreated or treated with HgCl 2 , 0.45 µm filtration, or filtration plus HgCl 2 , were stored in polypropylene or borosilicate glass vials for 0, 1, or 6 months. Mean A T of s les treated with HgCl 2 was reduced by as much as 49.1 µmol kg −1 (1.3%). Borosilicate glass elevated A T , possibly due to dissolving silicates. There was little change in A T of control and filtered s les stored in polypropylene, except for untreated groundwater (~ 4.1% reduction at 6 months). HgCl 2 concentrations of 0.02–0.05% reduced the A T of fresh, estuarine, and ground water s les by as much as 35.5 µmol kg −1 after 1 month, but had little effect on the A T of seawater. Adding glucose as a carbon source for microbial growth resulted in no A T changes in 0.45 µm-filtered s les. We suggest water s les intended for A T analyses can be filtered to 0.45 µm, and stored in polypropylene vials at 4 °C for at least 6 months. Borosilicate glassware and HgCl 2 can be avoided to prevent analytical uncertainties and reduce risks related to use of Hg 2+ .
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
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
Nitrous oxide hot moments and cold spots in a subtropical estuary: Floods and mangroves
Publisher: Elsevier BV
Date: 2022
Fifty Years of Sporadic Coral Reef Calcification Estimates at One Tree Island, Great Barrier Reef: Is it Enough to Imply Long Term Trends?
Publisher: Frontiers Media SA
Date: 04-06-2019
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
Corrigendum to "Groundwater and porewater as major sources of alkalinity to a fringing coral reef lagoon (Muri Lagoon, Cook Islands)" published in Biogeosciences, 10, 2467–2480, 2013
Publisher: Copernicus GmbH
Date: 30-10-2014
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.
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
Corrigendum to “Inorganic nitrogen transformations within permeable carbonate sands” [Continental Shelf Research, vol. 77, doi:10.1016/j.csr.2014.02.002]
Publisher: Elsevier BV
Date: 06-2014
Dissolved carbon, greenhouse gases, and δ13C dynamics in four estuaries across a land use gradient
Publisher: Springer Science and Business Media LLC
Date: 2019
Reply to: ‘Global predictions of coral reef dissolution in the Anthropocene’
Publisher: Springer Science and Business Media LLC
Date: 25-02-2022
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
Community sentiment on whale carcass beach burial and potential shark attraction
Publisher: Elsevier BV
Date: 06-2021
The influence of groundwater inputs and age on nutrient dynamics in a coral reef lagoon
Publisher: Elsevier BV
Date: 11-2014
Manganese and iron release from mangrove porewaters: A significant component of oceanic budgets?
Publisher: Elsevier BV
Date: 08-2016
Contrasting Radium-Derived Groundwater Exchange and Nutrient Lateral Fluxes in a Natural Mangrove Versus an Artificial Canal
Publisher: Springer Science and Business Media LLC
Date: 28-07-2020
Publisher Correction: Reply to: ‘Global predictions of coral reef dissolution in the Anthropocene’ (Communications Earth & Environment, (2022), 3, 1, (41), 10.1038/s43247-022-00364-2)
Publisher: Springer Science and Business Media LLC
Date: 07-03-2022
Significant Organic Carbon Accumulation in Two Coastal Acid Sulfate Soil Wetlands
Publisher: American Geophysical Union (AGU)
Date: 20-03-2019
DOI: 10.1029/2019GL082076
Modeling Catchment-Scale Nitrogen Losses Across a Land-Use Gradient in the Subtropics
Publisher: Frontiers Media SA
Date: 20-10-2020
Hysteresis between coral reef calcification and the seawater aragonite saturation state
Publisher: American Geophysical Union (AGU)
Date: 10-09-2013
DOI: 10.1002/GRL.50802
Are global mangrove carbon stocks driven by rainfall?
Publisher: American Geophysical Union (AGU)
Date: 10-2016
DOI: 10.1002/2016JG003510
Estuarine canal estate waters: Hotspots of CO2 outgassing driven by enhanced groundwater discharge?
Publisher: Elsevier BV
Date: 12-2014
Calcification and organic productivity at the world's southernmost coral reef
Publisher: Elsevier BV
Date: 12-2020
Stable isotopes reduce parameter uncertainty of an estuarine carbon cycling model
Publisher: Elsevier BV
Date: 05-2016
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
High porewater exchange in a mangrove-dominated estuary revealed from short-lived radium isotopes
Publisher: Elsevier BV
Date: 10-2017
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
Carbon cycling hysteresis in permeable carbonate sands over a diel cycle: Implications for ocean acidification
Publisher: Wiley
Date: 25-11-2012
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 accumulation in Amazonian floodplain lakes: A significant component of Amazon budgets?
Publisher: Wiley
Date: 29-01-2017
DOI: 10.1002/LOL2.10034
Abstract: The Amazon floodplains cover approximately 10% of the Amazon Basin and are composed of predominantly anoxic sediments that may store large amounts of carbon. Our study combines 210 Pb derived sedimentation rates from four recently analyzed sediment cores ( n = 4) with previously published organic carbon (OC) burial estimates ( n = 18) to provide a broad, first order estimate of carbon accumulation in Amazon floodplain lakes. The OC burial rates were 266 ± 57 g C m −2 yr −1 . This rate is several folds greater than those reported for lakes in arctic, boreal, temperate, and tropical regions. The large amount and spatial variation of OC burial rates in these floodplain lakes highlights the need for increased s ling efforts to better measure these potentially important components of the Amazon Basin carbon budget.
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.
Nitrate loads in sub-tropical headwater streams driven by intensive horticulture
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.ENVPOL.2018.08.074
Abstract: Nitrogen runoff from fertiliser intensive land uses has become an issue worldwide, contributing to algal blooms, hypoxic waters and aquatic bio ersity losses. This study assessed potential nutrient pollution from blueberry farms in subtropical Australia and examines whether nutrient loads were driven by groundwater discharge and/or surface water runoff. Streams downstream of eight blueberry farms were compared to eight nearby control sites without any blueberry activity. In the 90 day s le period, there were three rain events >90 mm day
Inorganic nitrogen transformations within permeable carbonate sands
Publisher: Elsevier BV
Date: 04-2014
Correction: Global patterns in mangrove soil carbon stocks and losses (Nature Climate Change (2017) DOI: 10.1038/nclimate3326)
Publisher: Springer Science and Business Media LLC
Date: 27-11-2018
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
Resolving groundwater sources to a coastal lagoon using major ions, nutrients and stable isotopes
Publisher: Springer Science and Business Media LLC
Date: 21-08-2021
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
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
Global patterns in mangrove soil carbon stocks and losses
Publisher: Springer Science and Business Media LLC
Date: 26-06-2017
DOI: 10.1038/NCLIMATE3326
Submarine groundwater discharge and associated nutrient and carbon inputs into Sydney Harbour (Australia)
Publisher: Elsevier BV
Date: 2020
Submarine Groundwater Discharge Releases CO2 to a Coral Reef
Publisher: American Chemical Society (ACS)
Date: 04-08-0005
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
Cryptic night-time trace metal and metalloid contamination in an intensively cultivated coastal catchment
Publisher: Elsevier BV
Date: 05-2021
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
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.
Large greenhouse gases emissions from China's lakes and reservoirs
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.WATRES.2018.09.053
Abstract: Freshwaters are important sources of greenhouse gases (GHGs) to the atmosphere that may partially offset the terrestrial carbon sink. However, current emission estimates from inland waters remain uncertain due to data paucity in key regions with a large freshwater surface area, such as China. Here, we show that the areal fluxes of GHGs (carbon dioxide, methane, and nitrous oxide) from lakes and reservoirs in China are much larger than previous estimates. Our work summarized data from 310 lakes and 153 reservoirs, and revealed diffusive emissions of 1.56 (95% confidence interval: 1.12-2.00) Tg C-CH
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.
Submarine groundwater discharge revealed by 224Ra and 223Ra in Coffs Harbour, Australia
Publisher: Springer Science and Business Media LLC
Date: 10-01-2019
Enhancement of denitrification in permeable carbonate sediment due to intra-granular porosity: A multi-scale modelling analysis
Publisher: Elsevier BV
Date: 09-2014
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.
Shifting nitrous oxide source/sink behaviour in a subtropical estuary revealed by automated time series observations
Publisher: Elsevier BV
Date: 07-2017
Effects of beach slope breaks on nearshore groundwater dynamics
Publisher: Wiley
Date: 06-2017
DOI: 10.1002/HYP.11196
Enhanced acidification of global coral reefs driven by regional biogeochemical feedbacks
Publisher: American Geophysical Union (AGU)
Date: 05-08-2014
DOI: 10.1002/2014GL060849
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
Permeable coral reef sediment dissolution driven by elevated pCO2 and pore water advection
Publisher: American Geophysical Union (AGU)
Date: 20-09-2013
DOI: 10.1002/GRL.50948
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
Groundwater and porewater as major sources of alkalinity to a fringing coral reef lagoon (Muri Lagoon, Cook Islands)
Publisher: Copernicus GmbH
Date: 15-04-2013
Abstract: Abstract. To better predict how ocean acidification will affect coral reefs, it is important to understand how biogeochemical cycles on reefs alter carbonate chemistry over various temporal and spatial scales. This study quantifies the contribution of shallow porewater exchange (as quantified from advective chamber incubations) and fresh groundwater discharge (as traced by 222Rn) to total alkalinity (TA) dynamics on a fringing coral reef lagoon along the southern Pacific island of Rarotonga over a tidal and diel cycle. Benthic alkalinity fluxes were affected by the advective circulation of water through permeable sediments, with net daily flux rates of carbonate alkalinity ranging from −1.55 to 7.76 mmol m−2 d−1, depending on the advection rate. Submarine groundwater discharge (SGD) was a source of TA to the lagoon, with the highest flux rates measured at low tide, and an average daily TA flux of 1080 mmol m−2 d−1 at the s ling site. Both sources of TA were important on a reef-wide basis, although SGD acted solely as a delivery mechanism of TA to the lagoon, while porewater advection was either a sink or source of TA dependent on the time of day. This study describes overlooked sources of TA to coral reef ecosystems that can potentially alter water column carbonate chemistry. We suggest that porewater and groundwater fluxes of TA should be taken into account in ocean acidification models in order to properly address changing carbonate chemistry within coral reef ecosystems.
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
Assessing pesticide, trace metal, and arsenic contamination in soils and dam sediments in a rapidly expanding horticultural area in Australia
Publisher: Springer Science and Business Media LLC
Date: 03-02-2021
Rare Earth Element and Radionuclide Distribution in Surface Sediments Along an Estuarine System Affected by Fertilizer Industry Contamination
Publisher: Springer Science and Business Media LLC
Date: 28-09-2013
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
Greenhouse gases and submarine groundwater discharge in a Sydney Harbour embayment (Australia)
Publisher: Elsevier BV
Date: 07-2018
The mangrove CO2 pump: Tidally driven pore‐water exchange
Publisher: Wiley
Date: 21-01-2021
DOI: 10.1002/LNO.11704
Land use drives nitrous oxide dynamics in estuaries on regional and global scales
Publisher: Wiley
Date: 24-02-2020
DOI: 10.1002/LNO.11426
Fire in the Earth System: Introduction to the Special Collection
Publisher: American Geophysical Union (AGU)
Date: 04-2023
DOI: 10.1029/2023JF007184
Abstract: Fire has always been an important component of many ecosystems, but anthropogenic global climate change is now altering fire regimes over much of Earth's land surface, spurring a more urgent need to understand the physical, biological, and chemical processes associated with fire as well as its effects on human societies. In 2020, AGU launched a Special Collection that spanned 10 journals, soliciting papers under the theme “Fire in the Earth System” to encourage state‐of‐the‐art publications in fire‐related science. The completed Special Collection comprises more than 100 papers. Here, we summarize the articles published in this collection, considering them to be grouped into seven themes: paleofire and its ties to climate evolution of fire patterns in the recent past and the future, including the effects of ongoing climate change physical (atmospheric) and chemical processes associated with fire ecosystem effects, including on biogeochemical cycles physical landscape change after fire and its associated hazards fire effects on water quality, air quality, and human health and new methods and technologies applied to fire research.
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
Elevated dissolved heavy metal discharge following rainfall downstream of intensive horticulture
Publisher: Elsevier BV
Date: 02-2020
Production of dissolved carbon and alkalinity during macroalgal wrack degradation on beaches: a mesocosm experiment with implications for blue carbon
Publisher: Springer Science and Business Media LLC
Date: 09-07-2022
DOI: 10.1007/S10533-022-00946-4
Abstract: Marine macroalgae are a key primary producer in coastal ecosystems, but are often overlooked in blue carbon inventories. Large quantities of macroalgal detritus deposit on beaches, but the fate of wrack carbon (C) is little understood. If most of the wrack carbon is respired back to CO 2 , there would be no net carbon sequestration. However, if most of the wrack carbon is converted to bicarbonate (alkalinity) or refractory DOC, wrack deposition would represent net carbon sequestration if at least part of the metabolic products (e.g., reduced Fe and S) are permanently removed (i.e., long-term burial) and the DOC is not remineralised. To investigate the release of macroalgal C via porewater and its potential to contribute to C sequestration (blue carbon), we monitored the degradation of Ecklonia radiata in flow-through mesocosms simulating tidal flushing on sandy beaches. Over 60 days, 81% of added E. radiata organic matter (OM) decomposed. Per 1 mol of detritus C, the degradation produced 0.48 ± 0.34 mol C of dissolved organic carbon (DOC) (59%) and 0.25 ± 0.07 mol C of dissolved inorganic carbon (DIC) (31%) in porewater, and a small amount of CO 2 (0.3 ± 0.0 mol C ca. 3%) which was emitted to the atmosphere. A significant amount of carbonate alkalinity was found in porewater, equating to 33% (0.27 ± 0.05 mol C) of the total degraded C. The degradation occurred in two phases. In the first phase (days 0–3), 27% of the OM degraded, releasing highly reactive DOC. In the second phase (days 4–60), the labile DOC was converted to DIC. The mechanisms underlying E. radiata degradation were sulphate reduction and ammonification. It is likely that the carbonate alkalinity was primarily produced through sulphate reduction. The formation of carbonate alkalinity and semi-labile or refractory DOC from beach wrack has the potential to play an overlooked role in coastal carbon cycling and contribute to marine carbon sequestration. Graphical abstract
Hydrological, geochemical and land use drivers of greenhouse gas dynamics in eleven sub-tropical streams
Publisher: Springer Science and Business Media LLC
Date: 14-03-2021
DOI: 10.1007/S00027-021-00791-X
Abstract: Greenhouse gas (GHG) emissions from freshwater streams are poorly quantified in sub-tropical climates, especially in the southern hemisphere where land use is rapidly changing. Here, we examined the distribution, potential drivers, and emissions of carbon dioxide (CO 2 ), nitrous oxide (N 2 O) and methane (CH 4 ) from eleven Australian freshwater streams with varying catchment land uses yet similar hydrology, geomorphology, and climate. These sub-tropical streams were a source of CO 2 (74 ± 39 mmol m −2 day −1 ), CH 4 (0.04 ± 0.06 mmol m −2 day −1 ), and N 2 O (4.01 ± 5.98 µmol m −2 day −1 ) to the atmosphere. CO 2 accounted for ~ 97% of all CO 2 -equivalent emissions with CH 4 (~ 1.5%) and N 2 O (~ 1.5%) playing a minor role. Episodic rainfall events drove changes in stream GHG due to the release of soil NO x (nitrate + nitrite) and dissolved organic carbon (DOC). Groundwater discharge as traced by radon ( 222 Rn, a natural groundwater tracer) was not an apparent source of CO 2 and CH 4 , but was a source of N 2 O in both agricultural and forest catchments. Land use played a subtle role on greenhouse gas dynamics. CO 2 and CH 4 increased with catchment forest cover during the wet period, while N 2 O and CH 4 increased with agricultural catchment area during the dry period. Overall, this study showed how DOC and NO x , land use, and rainfall events interact to drive spatial and temporal dynamics of GHG emissions in sub-tropical streams using multiple linear regression modelling. Increasing intensive agricultural land use will likely decrease regional CO 2 and CH 4 emissions, but increase N 2 O.
Methane emissions in seagrass meadows as a small offset to carbon sequestration
Publisher: Authorea, Inc.
Date: 14-12-2022
DOI: 10.22541/ESSOAR.167100373.34162103/V1
Abstract: Seagrass meadows are effective carbon sinks due to their high primary production and sequestration in sediments. However, methane (CH4) fluxes can partially counteract their carbon sink capacity. Here, we measured diffusive sediment-water and air-sea CO2 and CH4 fluxes in a coastal embayment dominated by Posidonia oceanica in the Mediterranean Sea. High resolution timeseries observations revealed large spatial and temporal variability in CH4 concentrations (2 to 36 nM). Higher emissions were observed in an area with dense seagrass meadows. A 6 − 40% decrease of CH4 concentration in the surface water around noon indicates that photosynthesis likely limits CH4 fluxes. Sediments were the major CH4 source as implied from radon (a natural porewater tracer) observations and evidence for methanogenesis in deeper sediments. CH4 sediment-water fluxes (0.1 ± 0.1 − 0.4 ± 0.1 µmol m-2 d-1) were higher than average water-air CH4 emissions (0.12 ± 0.10 µmol m-2 d-1), suggesting that dilution and CH4 oxidation in the water column could reduce net CH4 fluxes into the atmosphere. Overall, relatively low air-sea CH4 fluxes at this likely represent net emissions from subtidal seagrass habitats sites, which are not influenced by nearby allochthonous CH4 sources. The local CH4 emissions in P. oceanica offset less than 1% of the carbon burial in sediments (142 ± 69 g CO2eq m-2 yr-1). Combining our results with earlier observations in other seagrass meadows worldwide reveals that global CH4 emissions within seagrass meadows only offset a small fraction ( %) of carbon sequestration in sediments.
Whale carcass leachate plumes in beach groundwater: A potential shark attractant to the surf?
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.MARPOLBUL.2019.01.043
Abstract: With the recovery of whale populations, carcass strandings on beaches are growing. Beach burial is a common management option for stranded carcasses. However, communities fear shark attraction following leachate transport to the ocean via submarine groundwater discharge. Here, a sediment column mesocosm experiment indicated that carcasses can be a localised source of dissolved organic carbon (DOC), phosphate and ammonium to groundwater. The spatial reach of the leachate plume was 25 m onshore. Therefore, carcass leachate plumes would only potentially attract sharks to the surf under specific conditions not experienced during our experiments.
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
Tropical Beaches Attenuate Groundwater Nitrogen Pollution Flowing to the Ocean
Publisher: American Chemical Society (ACS)
Date: 04-06-2021
Natural attenuation of large anthropogenic nitrate loads in a subtropical stream revealed by δ15N and δ18O
Publisher: Elsevier BV
Date: 07-2021
Nitrogen transformations within a tropical subterranean estuary
Publisher: Elsevier BV
Date: 08-2014
Mercury dilution by autochthonous organic matter in a fertilized mangrove wetland
Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/J.ENVPOL.2016.02.002
Abstract: A dated sediment core from a highly-fertilized mangrove wetland located in Cubatão (SE Brazil) presented a negative correlation between mercury (Hg) and organic carbon contents. This is an unusual result for a metal with well-known affinity to organic matter. A dilution of Hg concentrations by autochthonous organic matter explained this observation, as revealed by carbon stable isotopes signatures (δ(13)C). Mercury dilution by the predominant mangrove-derived organic matter counterbalanced the positive influences of algal-derived organic matter and clay contents on Hg levels, suggesting that deleterious effects of Hg may be attenuated. Considering the current paradigm on the positive effect of organic matter on Hg concentrations in coastal sediments and the expected increase in mangrove organic matter burial due to natural and anthropogenic stimulations of primary production, predictions on the influences of organic matter on Hg accumulation in mangrove wetlands deserve caution.
Elevated rates of organic carbon, nitrogen, and phosphorus accumulation in a highly impacted mangrove wetland
Publisher: American Geophysical Union (AGU)
Date: 09-04-2014
DOI: 10.1002/2014GL059789
Sediment geochemistry in coastal maritime Antarctica (Admiralty Bay, King George Island): Evidence from rare earths and other elements
Publisher: Elsevier BV
Date: 12-2007
Submarine groundwater discharge drives nitrous oxide source/sink dynamics in a metropolitan estuary
Publisher: Wiley
Date: 15-02-2021
DOI: 10.1002/LNO.11710
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.
Organic carbon accumulation in oligotrophic coastal lakes in southern Brazil during the last century
Publisher: Springer Science and Business Media LLC
Date: 04-2021
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: Updates on Its Measurement Techniques, Geophysical Drivers, Magnitudes, and Effects
Publisher: Frontiers Media SA
Date: 10-2019
Mercury flux to estuarine sediments, derived from Pb-210 and Cs-137 geochronologies (Guaratuba Bay, Brazil)
Publisher: Elsevier BV
Date: 09-2006
DOI: 10.1016/J.MARPOLBUL.2006.06.004
Abstract: A sediment core from Guaratuba Bay was used to indicate possible Hg modifications to this coastal environment brought about by growing agricultural activity. Sedimentation rates were estimated to be 6.1 mm/year and 5.2 mm/year through 210Pb and 137Cs geochronologies, respectively. Mercury concentrations and organic matter ratios in the surface layers are greater than in the older sediments, supporting the hypothesis of anthropogenic enrichment. Results show that the Hg flux has raised more than twofold during the second half of the 20th century. These results point to the need for further studies to substantiate the hypothesis of anthropogenic enrichment and to quantify point sources of Hg to this estuary.
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
Altered groundwater discharge and associated carbon fluxes in a wetland-drained coastal canal
Publisher: Elsevier BV
Date: 04-2020
Groundwater dynamics in subterranean estuaries of coastal unconfined aquifers: Controls on submarine groundwater discharge and chemical inputs to the ocean
Publisher: Elsevier BV
Date: 05-2018
Pore-water exchange flushes blue carbon from intertidal saltmarsh sediments into the sea
Publisher: Wiley
Date: 11-02-2022
DOI: 10.1002/LOL2.10236
Abstract: We quantified whether pore‐water exchange flushes out saltmarsh sediment carbon, driving carbon outwelling into the ocean and outgassing into the atmosphere. Radon‐derived pore‐water exchange released 1.8 times more sediment carbon in the wet than in dry season. Both crab burrow flushing and delayed seepage of surface water infiltrating sediments during the spring tide released sediment carbon to surface waters. The outwelling flux of dissolved inorganic carbon exceeded dissolved organic carbon. Carbon dioxide and methane emissions were 169 and 0.25 mmol m −2 d −1 , respectively. Pore‐water carbon fluxes exceeded carbon outwelling. This requires some carbon processing within the saltmarsh (e.g., degradation or outgassing to the atmosphere) before pore‐water carbon is exported to the ocean. Overall, pore‐water exchange and outwelling are key components of saltmarsh carbon budgets and should be considered when assessing their carbon sequestration potential and strategies to mitigate climate change.
Estimating submarine groundwater discharge in a South Pacific coral reef lagoon using different radioisotope and geophysical approaches
Publisher: Elsevier BV
Date: 10-2013
Radium-derived porewater exchange and dissolved N and P fluxes in mangroves
Publisher: Elsevier BV
Date: 03-2017
Large aquatic nitrous oxide emissions downstream of intensive horticulture driven by rain events
Publisher: Elsevier BV
Date: 05-2021
Carbon dioxide dynamics in a tropical estuary over seasonal and rain-event time scales
Publisher: Elsevier BV
Date: 12-2020
Carbon dioxide hydrodynamics along a wetland-lake-stream-waterfall continuum (Blue Mountains, Australia)
Publisher: Elsevier BV
Date: 07-2021
Mangrove sediments reveal records of development during the previous century (Coffs Creek estuary, Australia)
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.MARPOLBUL.2017.05.052
Abstract: A mangrove sediment core was studied to evaluate possible pollution of an urban estuary in Coffs Harbour, Australia. The heavy metal and nutrient profiles revealed a ~2.5-fold enrichment in more recent sediments. Lead-210 dating showed increasing phosphorous (P) and copper (Cu) accumulation following agricultural activity and population growth in the catchment after 1950. In contrast, nitrogen (N) did not show enrichment suggesting no external sources. Mercury (Hg) depositional fluxes and recent enrichment may be associated to an increase in fossil fuel emissions in the region. Down-core lead (Pb) profiles reflect an increase in leaded gasoline in the 1950s, then a decrease as a result of phasing out leaded gasoline in 1986. The heavy metal and nutrient depositional fluxes are well preserved in mangrove sediments and were related to historical events in the catchment.
Groundwater methane in a potential coal seam gas extraction region
Publisher: Elsevier BV
Date: 09-2015
Breathing of a coral cay: Tracing tidally driven seawater recirculation in permeable coral reef sediments
Publisher: American Geophysical Union (AGU)
Date: 12-2010
DOI: 10.1029/2010JC006510
Abstract: Coral reefs are characterized by high gross productivity in spite of low nutrient concentrations. This apparent paradox may be partially reconciled if seawater recirculation in permeable sediments over large (meters) and long (hours to days) scales is an important source of recycled nitrogen and phosphorus to coral reefs. In this paper we use radon ( 222 Rn, a natural tracer) to quantify tidally driven pore water (or groundwater) exchange between (1) an offshore coral cay island and its fringing reef lagoon and (2) a reef lagoon and the surrounding ocean. As seawater infiltrates Heron Island at high tide, it acquires a radon signal that can be detected when pore waters emerge from carbonate sands at low tide. A nonsteady state model indicated that vertical pore water upwelling rates (or saline submarine groundwater discharge) were cm/d within the reef lagoon and cm/d outside the lagoon at low tide. Within the lagoon, tidal pumping and temperature‐driven convection were the main driving forces of pore water advection. At low tide, the reef lagoon level is about 1 m higher than the surrounding ocean. As a result, a steep hydraulic gradient develops at the reef edge, driving unidirectional filtration through the reef framework. Groundwaters were highly enriched in nitrate (average of 530 μ mol, likely influenced by bird guano) relative to lagoon waters (1.9 μ mol). Rough but conservative estimates indicated that groundwater‐derived nitrate fluxes (7.9 mmol/m 2 /d) can replace the entire lagoon nitrate inventory every days. We speculate that as offshore coral islands “breath” (inhale seawater at high tide and exhale groundwater at low tide), they release nutrients that lead to sustained productivity within coral reefs.
Effects of alongshore morphology on groundwater flow and solute transport in a nearshore aquifer
Publisher: American Geophysical Union (AGU)
Date: 02-2016
DOI: 10.1002/2015WR017420
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
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.
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
Changes in global groundwater organic carbon driven by climate change and urbanization
Publisher: Springer Science and Business Media LLC
Date: 09-03-2020
DOI: 10.1038/S41467-020-14946-1
Abstract: Climate change and urbanization can increase pressures on groundwater resources, but little is known about how groundwater quality will change. Here, we use a global synthesis ( n = 9,404) to reveal the drivers of dissolved organic carbon (DOC), which is an important component of water chemistry and substrate for microorganisms that control biogeochemical reactions. Dissolved inorganic chemistry, local climate and land use explained ~ 31% of observed variability in groundwater DOC, whilst aquifer age explained an additional 16%. We identify a 19% increase in DOC associated with urban land cover. We predict major groundwater DOC increases following changes in precipitation and temperature in key areas relying on groundwater. Climate change and conversion of natural or agricultural areas to urban areas will decrease groundwater quality and increase water treatment costs, compounding existing constraints on groundwater resources.
Significant nitrate attenuation in a mangrove-fringed estuary during a flood-chase experiment
Publisher: Elsevier BV
Date: 10-2019
DOI: 10.1016/J.ENVPOL.2019.06.060
Abstract: Intertidal wetlands can sequester pollutants along estuarine conduits. Here we test the effectiveness of a mangrove-dominated estuary in removing dissolved nitrogen during a rain event. We intensively and simultaneously s led surface water nutrients upstream and downstream of an estuary before, during and after a 63 mm rain event in Coffs Creek (Australia). NO
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
Appreciating GBC 2022 Reviewers
Publisher: American Geophysical Union (AGU)
Date: 08-2023
DOI: 10.1029/2023GB007867
Abstract: The Editors of the Global Biogeochemical Cycles express their appreciation to those who served as peer reviewers for the journal in 2022.
Nutrient and Trace Metal Fluxes into Estuarine Sediments Linked to Historical and Expanding Agricultural Activity (Hearnes Lake, Australia)
Publisher: Springer Science and Business Media LLC
Date: 21-03-2019
Groundwater Carbon Exports Exceed Sediment Carbon Burial in a Salt Marsh
Publisher: Springer Science and Business Media LLC
Date: 02-12-2022
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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