ORCID Profile
0000-0001-9914-5418
Current Organisations
Southern Cross University
,
Lincoln 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)
Isotope Geochemistry | Environmental Monitoring | Inorganic Geochemistry | Geochemistry | Microbial Ecology | Other Chemical Sciences | Environmental Chemistry (incl. Atmospheric Chemistry) |
ANZSRC Socio-Economic Objective (SEO)
Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Rehabilitation of Degraded Fresh, Ground and Surface Water Environments | Physical and Chemical Conditions of Water in Fresh, Ground and Surface Water Environments (excl. Urban and Industrial Use) | Soils not elsewhere classified | Ecosystem Assessment and Management of Marine Environments
Related Links
Publications
Chronically stressed benthic macroinvertebrate communities exhibit limited effects on ecosystem function in a microtidal estuary
Publisher: Inter-Research Science Center
Date: 24-11-2022
DOI: 10.3354/MEPS14175
Abstract: Anthropogenically driven alterations to coastal sediments and their benthic macroinvertebrate communities impair ecosystem function. However, this paradigm is yet to be tested in ecosystems that typically harbour underdeveloped communities lacking larger bioturbating species. Here, we investigated the effects of sediment condition and macroinvertebrate communities on benthic metabolism, nutrient exchange and denitrification (N 2 production), and assessed the relative importance of taxon richness, abundance, biomass and community bioturbation potential in influencing these processes in 2 regions of the highly modified, microtidal Peel-Harvey Estuary in temperate Western Australia. Sediment condition influenced benthic metabolism more than the macroinvertebrate community, whereas the reverse was true for nutrient exchange. Denitrification was driven by sediment condition and the community in the upper and lower estuary, respectively, highlighting the change in controls of this nitrogen-removal process within estuaries. Overall, benthic macroinvertebrates had little to no effect on many ecosystem processes, exhibiting the limited functional role played by these chronically stressed biota in this estuary. There was also no interaction between sediment condition and the community, suggesting a functional decoupling between these 2 ecosystem components. Where significant macroinvertebrate effects were detected, community biomass was the most frequently selected predictor, demonstrating its fundamental role in ecosystem function. This study reveals pressing implications of what might be expected when benthic environments become particularly degraded and the highly limited potential of the resultant benthic macroinvertebrate communities to provide key ecosystem services such as nutrient processing.
Defaunation by deoxygenation: efficacy and divergent responses of estuarine macroinvertebrates
Publisher: Inter-Research Science Center
Date: 24-11-2022
DOI: 10.3354/MEPS14199
Abstract: Understanding the influence of macroinvertebrates on ecosystem function often relies on experimental defaunation with methods that remove fauna through minimal s le disturbance. Defaunation is challenging and can lead to confounding effects and/or loss of empirical information when unsuccessful. We evaluated the ability of a deoxygenation treatment to remove macroinvertebrates from sediment cores collected in 2 regions of a microtidal estuary. Only 1 of 16 cores was fully defaunated following 3 deoxygenation cycles. To counteract confounding effects of partial defaunation, we quantified the biomass remaining in each core and used these data as a covariate in statistical models. The unremoved biomass had, in some cases, significant effects on alkalinity fluxes, with positive linear relationships evident, and net phosphate fluxes. The community in the upper estuary that regularly experiences hypoxia exhibited stronger sediment emergence responses (82-100%). The remaining fauna were spread equally among annelids, molluscs and arthropods in abundance, although arthropods dominated the biomass. In contrast, fewer macroinvertebrates emerged from sediments from the lower estuary (47-89%), with most of the remaining biomass and abundance being annelids and molluscs. These findings suggest that estuarine taxa have ergent responses to hypoxia and that regional communities are variably prone to eradication of sensitive taxa. Our study shows how the use of defaunation by deoxygenation can create systematic bias, particularly when comparing areas with disparate in situ oxygen regimes, and provides a way to quantitively account for partial defaunation without sacrificing statistical power or using overly destructive methods.
Importance of habitat diversity to changes in benthic metabolism over land-use gradients: evidence from three subtropical estuaries
Publisher: Inter-Research Science Center
Date: 21-11-2019
DOI: 10.3354/MEPS13147
Update on Our Action Plan for Equity, Inclusion, and Diversity in Publishing at JGR: Biogeosciences
Publisher: American Geophysical Union (AGU)
Date: 26-07-2023
DOI: 10.1029/2023JG007712
Abstract: We made a commitment to better include underrepresented members of our community in the publication pipeline of JGR: Biogeosciences . This commitment consists of regular updates on our policies and practices, and concrete actions we intend to implement over the next year. So far, our progress to tackle biases and ensure equitable research in the biogeosciences has focused on improving ersity of our associate editor and reviewer pools, increasing awareness of unconscious bias in peer‐review, and promoting inclusion in global collaborations. In this update, we explore manuscript submissions and manuscript decisions by gender, and we present a pilot that aims to promote ethical and equitable global collaborations in resource‐poor settings. We end our editorial by presenting our next set of actions that we plan on completing over the next year, which include a more thorough analysis of reviewer demographics.
Land-use intensity alters both the source and fate of CO2 within eight sub-tropical estuaries
Publisher: Elsevier BV
Date: 2020
Effects of denitrification and transport on the isotopic composition of nitrate (δ18O, δ15N) in freshwater systems
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.SCITOTENV.2018.10.065
Abstract: Nitrate isotopes (δ
Flow regulates biological NO3− and N2O production in a turbid sub-tropical stream
Publisher: Elsevier BV
Date: 08-2021
A Modeling Approach for Addressing Sensitivity and Uncertainty of Estuarine Greenhouse Gas (CO2 and CH4) Dynamics
Publisher: American Geophysical Union (AGU)
Date: 06-2022
DOI: 10.1029/2021JG006722
Abstract: Estuaries make an important contribution to the global greenhouse gas budget. Yet modeling predictions of carbon dioxide (CO 2 ) and methane (CH 4 ) emissions from estuaries remain highly uncertain due to both simplified assumptions about the underpinning hydrologic and biologic processes and inadequate data availability to uniquely define parameters related to CO 2 and CH 4 processes. This study presents a modeling framework to quantify the sensitivity and uncertainty of predicted CO 2 and CH 4 concentrations and emissions, which is demonstrated through application to a subtropical urban estuary (Brisbane River, Australia). A 3D hydrodynamic‐biogeochemical model was constructed, and calibrated using the model‐independent Parameter ESTimation software (PEST) with field data sets that captured strong gradients of CO 2 and CH 4 concentrations and emissions along the estuary. The approach refined uncertainty in the estimation of whole‐estuary annual emissions, and enabled us to assess the sensitivity and uncertainty of CO 2 and CH 4 dynamics. Estuarine CO 2 concentrations were most sensitive to uncertainty in riverine inputs, whereas estuarine CH 4 concentrations were most sensitive to sediment production and pelagic oxidation. Over the modeled year, variance in the daily fluctuations in carbon emissions from this case‐study spanned the full range of emission rates reported for estuaries around the world, highlighting that spatially or temporally limited s ling regimes could significantly bias estuarine greenhouse gas emission estimates. The combination of targeted field c aigns with the modeling approach presented in this study can help to improve carbon budgeting in estuaries, reduce uncertainty in emission estimates, and support management strategies to reduce or offset estuary greenhouse gas emissions.
Land management between crops affects soil inorganic nitrogen balance in a tropical rice system
Publisher: Springer Science and Business Media LLC
Date: 10-2014
Anoxic nitrogen cycling in a hydrocarbon and ammonium contaminated aquifer
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.WATRES.2018.06.005
Abstract: Nitrogen fate and transport through contaminated groundwater systems, where N is both ubiquitous and commonly limits pollutant attenuation, must be re-evaluated given evidence for new potential microbial N pathways. We addressed this by measuring the isotopic composition of dissolved inorganic N (DIN = NH
An integrated assessment of nitrogen source, transformation and fate within an intensive dairy system to inform management change
Publisher: Public Library of Science (PLoS)
Date: 23-07-2019
Investigating “net” provenance, N source, transformation and fate within hydrologically isolated grassland plots
Publisher: Elsevier BV
Date: 04-2018
Influence of artificial drainage system design on the nitrogen attenuation potential of gley soils: Evidence from hydrochemical and isotope studies under field-scale conditions
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.JENVMAN.2017.11.069
Abstract: In North Atlantic Europe intensive dairy farms have a low nitrogen (N) use efficiency, with high N surpluses often negatively affecting water quality. Low feed input systems on heavy textured soils often need artificial drainage to utilise low cost grassland and remain profitable. Heavy textured soils have high but variable N attenuation potential, due to soil heterogeneity. Furthermore, drainage system design can influence the potential for N attenuation and subsequent N loadings in waters receiving drainage from such soils. The present study utilises end of pipe, open ditch and shallow groundwater s ling points across five sites in SW Ireland to compare and rank sites based on N surplus, water quality and "net denitrification", and to develop a conceptual framework for the improved management of heavy textured dairy sites to inform water quality N sustainability. This includes both drainage design and "net denitrification" criterion, as developed within this study.N surplus ranged from 211 to 292 kg N/ha (mean of 252 kg N/sourha) with a common source of organic N across all locations. The predicted soil organic matter (SOM) N release potential from top-subsoil layers was high, ranging from 115 to >146 kg N/ha. Stable isotopes analyses showed spatial variation in the extent of specific N-biotransformation processes, according to drainage location and design. Across all sites, nitrate (NO
δ18O as a tracer of PO43- losses from agricultural landscapes
Publisher: Wiley
Date: 17-03-2022
Warming and redistribution of nitrogen inputs drive an increase in terrestrial nitrous oxide emission factor
Publisher: Springer Science and Business Media LLC
Date: 25-07-2022
DOI: 10.1038/S41467-022-32001-Z
Abstract: Anthropogenic nitrogen inputs cause major negative environmental impacts, including emissions of the important greenhouse gas N 2 O. Despite their importance, shifts in terrestrial N loss pathways driven by global change are highly uncertain. Here we present a coupled soil-atmosphere isotope model (IsoTONE) to quantify terrestrial N losses and N 2 O emission factors from 1850-2020. We find that N inputs from atmospheric deposition caused 51% of anthropogenic N 2 O emissions from soils in 2020. The mean effective global emission factor for N 2 O was 4.3 ± 0.3% in 2020 (weighted by N inputs), much higher than the surface area-weighted mean (1.1 ± 0.1%). Climate change and spatial redistribution of fertilisation N inputs have driven an increase in global emission factor over the past century, which accounts for 18% of the anthropogenic soil flux in 2020. Predicted increases in fertilisation in emerging economies will accelerate N 2 O-driven climate warming in coming decades, unless targeted mitigation measures are introduced.
Denitrification, anammox, and dissimilatory nitrate reduction to ammonium across a mosaic of estuarine benthic habitats
Publisher: Wiley
Date: 25-12-2020
DOI: 10.1002/LNO.11681
Importance of internal dissolved organic nitrogen loading and cycling in a small and heavily modified coastal lagoon
Publisher: Springer Science and Business Media LLC
Date: 27-06-2021
Nitrate isotopes ( δ 15 N, δ 18 O) in precipitation: best practices from an international co
Publisher: Informa UK Limited
Date: 22-02-2023
δ18O as a tracer of PO43- losses from agricultural landscapes
Publisher: Elsevier BV
Date: 09-2022
DOI: 10.1016/J.JENVMAN.2022.115299
Abstract: Accurately tracing the sources and fate of excess PO
Divergent Gas Transfer Velocities of CO2, CH4, and N2O Over Spatial and Temporal Gradients in a Subtropical Estuary
Publisher: American Geophysical Union (AGU)
Date: 10-2021
DOI: 10.1029/2021JG006270
Abstract: High global uncertainties remain in water‐air CO 2 , CH 4 , and N 2 O fluxes from estuaries due to spatial and temporal variability and the poor predictability of the gas transfer velocity ( k 600 ). This is the first study that directly compares k 600 of CO 2 , CH 4 , and N 2 O in an estuary with the aim to evaluate the accuracy of using a uniform k 600 value for estimating water‐air fluxes. We calculated 155 k 600 values from CO 2 , CH 4 , and N 2 O fluxes over spatial (across, along) and temporal (tidal cycle) surveys in the subtropical Maroochy estuary using the floating chamber method. Combined k 600 values showed a large range over the entire estuary (0.1–198.6 cm h −1 ) with slightly lower k 600 in the lower compared to the upper estuary. Overall, temporal variability was greater than spatial variability of k 600 . We found the highest variability of k 600 between gas species in the lower estuary, whereas the variability was less distinct in the upper estuary. In the Maroochy estuary, k 600 CO 2 (mean 26.4 ± 37.3 cm h −1 ) was mostly higher than k 600 CH 4 (mean 10.9 ± 10.6 cm h −1 ) and k 600 N 2 O (mean 9.9 ± 12.3 cm h −1 ), likely due to chemical and enzymatic enhancements and/or microbial activity in the surface microlayer. We demonstrate that empirical k 600 models intended for CO 2 may not accurately predict CH 4 and N 2 O fluxes in estuaries. Our tested k 600 models predicted the measured fluxes within an uncertainty range of 5%–40% (over or underestimation), but precise flux estimates should be based on in situ k 600 of all three gases.
δ15N patterns in three subtropical estuaries show switch from nitrogen “reactors” to “pipes” with increasing degradation
Publisher: Wiley
Date: 19-11-2018
DOI: 10.1002/LNO.11080
Ammonia volatilisation is not the dominant factor in determining the soil nitrate isotopic composition of pasture systems
Publisher: Elsevier BV
Date: 2015
Mackinawite (FeS) Chemodenitrification of Nitrate (NO3–) under Acidic to Neutral pH Conditions and Its Stable N and O Isotope Dynamics
Publisher: American Chemical Society (ACS)
Date: 28-11-2022
Spatial and temporal variations in nitrogen export from a New Zealand pastoral catchment revealed by stream water nitrate isotopic composition
Publisher: American Geophysical Union (AGU)
Date: 04-2016
DOI: 10.1002/2015WR017642
Char amendments impact soil nitrous oxide production during ammonia oxidation
Publisher: Wiley
Date: 08-08-2014
Seasonal and spatial controls on N2O concentrations and emissions in low-nitrogen estuaries: Evidence from three tropical systems
Publisher: Elsevier BV
Date: 04-2020
Seasonal and spatial controls on N2O concentrations and emissions in low-nitrogen estuaries: Evidence from three tropical systems
Publisher: Cold Spring Harbor Laboratory
Date: 26-05-2019
DOI: 10.1101/650705
Abstract: Estuarine N 2 O emissions contribute to the atmospheric N 2 O budget, but little is known about estuary N 2 O fluxes under low dissolved inorganic nitrogen (DIN) conditions. We present high-resolution spatial surveys of N 2 O concentrations and water-air fluxes in three low-DIN (NO 3 − 30 µ mol L −1 ) tropical estuaries in Queensland, Australia (Johnstone River, Fitzroy River, Constant Creek) during consecutive wet and dry seasons. Constant Creek had the lowest concentrations of dissolved inorganic nitrogen (DIN 0.01 to 5.4 µ mol L −1 of NO 3 − and 0.09 to 13.6 µ mol L −1 of NH 4 + ) and N 2 O (93–132% saturation), and associated lowest N 2 O emissions (– 1.4 to 8.4 µ mol m −2 d −1 ) in both seasons. The other two estuaries exhibited higher DIN inputs and higher N 2 O emissions. The Johnstone River Estuary had the highest N 2 O concentrations (97–245% saturation) and emissions (– 0.03 to 25.7 µ mol m −2 d −1 ), driven by groundwater inputs from upstream sources, with increased N 2 O input in the wet season. In the Fitzroy River Estuary, N 2 O concentrations (100–204% saturation) and emissions (0.03–19.5 µ mol m −2 d −1 ) were associated with wastewater inputs, which had a larger effect during the dry season and were diluted during the wet season. Overall N 2 O emissions from the three tropical estuaries were low compared to previous studies, and at times water-air N 2 O fluxes were actually negative, indicating that N 2 O consumption occurred. Low water column NO 3 − concentration (i.e. 5 µ mol L −1 ) appears to promote negative water-air N 2 O fluxes in estuary environments considering the number of estuaries and mangrove creeks where DIN falls below this threshold, negative water-air N 2 O fluxes are likely common.
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
Abiotic reduction of nitrate to ammonium by iron (oxy)(hydr)oxides and its stable isotope (δ15N, δ18O) dynamics
Publisher: Elsevier BV
Date: 04-2023
Unweathered Wood Biochar Impact on Nitrous Oxide Emissions from a Bovine‐Urine‐Amended Pasture Soil
Publisher: Wiley
Date: 05-2010
Multi-species measurements of nitrogen isotopic composition reveal the spatial constraints and biological drivers of ammonium attenuation across a highly contaminated groundwater system
Publisher: Elsevier BV
Date: 07-2016
DOI: 10.1016/J.WATRES.2016.04.025
Abstract: Groundwater under industrial sites is characterised by heterogeneous chemical mixtures, making it difficult to assess the fate and transport of in idual contaminants. Quantifying the in-situ biological removal (attenuation) of nitrogen (N) is particularly difficult due to its reactivity and ubiquity. Here a multi-isotope approach is developed to distinguish N sources and sinks within groundwater affected by complex industrial pollution. S les were collected from 70 wells across the two aquifers underlying a historic industrial area in Belgium. Below the industrial site the groundwater contained up to 1000 mg N l(-1) ammonium (NH4(+)) and 300 mg N l(-1) nitrate (NO3(-)), while downgradient concentrations decreased to ∼1 mg l(-1) DIN ([DIN] = [NH4(+)N] + [NO3(-)N] + [NO2(-)N]). Mean δ(15)N-DIN increased from ∼2‰ to +20‰ over this flow path, broadly confirming that biological N attenuation drove the measured concentration decrease. Multi-variate analysis of water chemistry identified two distinct NH4(+) sources (δ(15)NNH4(+) from -14‰ and +5‰) within the contaminated zone of both aquifers. Nitrate dual isotopes co-varied (δ(15)N: -3‰ - +60‰ δ(18)O: 0‰ - +50‰) within the range expected for coupled nitrification and denitrification of the identified sources. The fact that δ(15)NNO2(-) values were 50‰-20‰ less than δ(15)NNH4(+) values in the majority of wells confirmed that nitrification controlled N turnover across the site. However, the fact that δ(15)NNO2(-) was greater than δ(15)NNH4(+) in wells with the highest [NH4(+)] shows that an autotrophic NO2(-) reduction pathway (anaerobic NH4(+) oxidation or nitrifier-denitrification) drove N attenuation closest to the contaminant plume. This direct empirical evidence that both autotrophic and heterotrophic biogeochemical processes drive N attenuation in contaminated aquifers demonstrates the power of multiple N isotopes to untangle N cycling in highly complex systems.
Biofilm-specific uptake does not explain differences in whole-stream DOC tracer uptake between a forest and an agricultural stream
Publisher: Springer Science and Business Media LLC
Date: 06-2019
Land‐Use Intensity Increases Benthic N2O Emissions Across Three Sub‐Tropical Estuaries
Publisher: American Geophysical Union (AGU)
Date: 08-2022
DOI: 10.1029/2022JG006899
Abstract: Estuaries play an important role in regulating nitrous oxide (N 2 O) fluxes to the atmosphere, but little is known about how catchment land‐use changes influence benthic N 2 O cycling. We measured seasonal benthic N 2 O fluxes and constructed N 2 O budgets in three sub‐tropical estuaries draining catchments with contrasting levels of land‐use intensity. Benthic habitats were a net N 2 O sink in the minimally impacted Noosa River Estuary (−287 nmol m −2 h −1 ) and a net source of N 2 O in the highly impacted Brisbane River Estuary (126 nmol m −2 h −1 ). Vegetated habitats can act as an important sink of N 2 O with uptakes of −286 and −35 nmol m −2 h −1 in the Noosa and Maroochy River Estuaries, respectively. Benthic N 2 O fluxes were significantly correlated with benthic NO 3 − fluxes, suggesting NO 3 − availability was an important control on benthic N 2 O fluxes. Combining benthic flux data with surface water N 2 O emissions measurements showed that increased benthic N 2 O fluxes helped drive increasing water–air N 2 O emissions over the land‐use intensity gradient. Overall, our results show that land‐use driven changes to both the ersity and sediment composition of benthic habitats play an important role in regulating N 2 O dynamics in estuarine ecosystems. This highlights that both sediment quality and nitrogen loading need to be considered in order to reduce emissions of greenhouse gases in the coastal ecosystems.
Microbial nitrogen transformation in constructed wetlands treating contaminated groundwater
Publisher: Springer Science and Business Media LLC
Date: 20-09-2014
DOI: 10.1007/S11356-014-3575-3
Abstract: Pathways of ammonium (NH4 (+)) removal were investigated using the stable isotope approach in constructed wetlands (CWs). We investigated and compared several types of CWs: planted horizontal subsurface flow (HSSF), unplanted HSSF, and floating plant root mat (FPRM), including spatial and seasonal variations. Plant presence was the key factor influencing efficiency of NH4 (+) removal in all CWs, what was illustrated by lower NH4 (+)-N removal by the unplanted HSSF CW in comparison with planted CWs. No statistically significant differences in NH4 (+) removal efficiencies between seasons were detected. Even though plant uptake accounted for 32-100 % of NH4 (+) removal during spring and summer in planted CWs, throughout the year, most of NH4 (+) was removed via simultaneous nitrification-denitrification, what was clearly shown by linear increase of δ(15)N-NH4 (+) with decrease of loads along the flow path and absence of nitrate (NO3 (-)) accumulation. Average yearly enrichment factor for nitrification was -7.9 ‰ for planted HSSF CW and -5.8 ‰ for FPRM. Lack of enrichment for δ(15)N-NO3 (-) implied that other processes, such as nitrification and mineralization were superimposed on denitrification and makes the stable isotope approach unsuitable for the estimation of denitrification in the systems obtaining NH4 (+) rich inflow water.
Changing sediment and surface water processes increase CH4 emissions from human-impacted estuaries
Publisher: Elsevier BV
Date: 07-2020
Hippuric acid and benzoic acid inhibition of urine derived N2O emissions from soil
Publisher: Wiley
Date: 02-07-2009
Related Organisations
University Of Aberdeen
Location: United Kingdom of Great Britain and Northern Ireland
Related Funding Activities
Untangling The Controls On Nitrous Oxide Emissions From Braided Rivers
Start Date: 2022
End Date: 2025
Funder: Marsden Fund
View Funded ActivityLinkage Projects - Grant ID: LP190100271
Start Date: 06-2020
End Date: 12-2025
Amount: $354,935.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE200100156
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End Date: 12-2021
Amount: $471,000.00
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View Funded ActivityLinkage Projects - Grant ID: LP200200910
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End Date: 12-2024
Amount: $704,711.00
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