ORCID Profile
0000-0002-0444-3488
Current Organisation
Monash 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)
Other Chemical Sciences | Environmental Chemistry (incl. Atmospheric Chemistry) | Isotope Geochemistry | Environmental Chemistry (Incl. Atmospheric Chemistry) | Geochronology And Isotope Geochemistry | Marine and Estuarine Ecology (incl. Marine Ichthyology) | Civil Engineering | Ecosystem Function | Environmental Sciences Not Elsewhere Classified | Ecology | Environmental Management | Water Resources Engineering | Analytical Chemistry | Environmental Science and Management | Microbial Ecology | Geochemistry | Microbiology | Analytical Spectrometry | Chemical Characterisation of Materials | Chemical Oceanography | Marine Geoscience | Conservation and Biodiversity | Geochemistry not elsewhere classified | Water Quality Engineering | Environmental Science and Management not elsewhere classified | Analytical Spectrometry | Separation Science | Flow Analysis | Environmental Technologies | Water And Sanitary Engineering |
ANZSRC Socio-Economic Objective (SEO)
Estuarine and lagoon areas | Physical and chemical conditions | Integrated (ecosystem) assessment and management | Rehabilitation of degraded coastal and estuarine areas | Physical and Chemical Conditions of Water in Marine Environments | Physical and Chemical Conditions of Water in Coastal and Estuarine Environments | Ecosystem Assessment and Management of Coastal and Estuarine Environments | Coastal and Estuarine Land Management | Coastal and Estuarine Water Management | Coastal and Estuarine Flora, Fauna and Biodiversity | Soils not elsewhere classified | Climate change | Land and water management | Integrated (ecosystem) assessment and management | Physical and Chemical Conditions of Water in Fresh, Ground and Surface Water Environments (excl. Urban and Industrial Use) | Treatments (e.g. chemicals, antibiotics) | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Prevention and treatment of pollution | Other | Expanding Knowledge in the Medical and Health Sciences | Water Services and Utilities | Rehabilitation of Degraded Fresh, Ground and Surface Water Environments | Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Biological Sciences | Water and Waste Services not elsewhere classified
Related Links
Publications
The negligible effect of bed form migration on denitrification in hyporheic zones of permeable sediments
Publisher: American Geophysical Union (AGU)
Date: 03-2015
DOI: 10.1002/2014JG002852
Taking the “Waste” Out of “Wastewater” for Human Water Security and Ecosystem Sustainability
Publisher: American Association for the Advancement of Science (AAAS)
Date: 10-08-2012
Abstract: Humans create vast quantities of wastewater through inefficiencies and poor management of water systems. The wasting of water poses sustainability challenges, depletes energy reserves, and undermines human water security and ecosystem health. Here we review emerging approaches for reusing wastewater and minimizing its generation. These complementary options make the most of scarce freshwater resources, serve the varying water needs of both developed and developing countries, and confer a variety of environmental benefits. Their widespread adoption will require changing how freshwater is sourced, used, managed, and priced.
Niche‐dependent trophic position distributions among primary, secondary and tertiary consumers
Publisher: Wiley
Date: 14-11-2015
DOI: 10.1111/OIK.02486
Technical note: Inexpensive modification of Exetainers for the reliable storage of trace-level hydrogen and carbon monoxide gas samples
Publisher: Copernicus GmbH
Date: 29-01-2021
Abstract: Abstract. Atmospheric trace gases such as dihydrogen (H2), carbon monoxide (CO) and methane (CH4) play important roles in microbial metabolism and biogeochemical cycles. Analysis of these gases at trace levels requires reliable storage of discrete s les of low volume. While commercial s ling vials such as Exetainers® have been tested for CH4 and other greenhouse gases, no information on reliable storage is available for H2 and CO. We show that vials sealed with butyl rubber stoppers are not suitable for storing H2 and CO due to release of these gases from rubber material. Treating butyl septa with NaOH reduced trace-gas release, but contamination was still substantial, with H2 and CO mixing ratios in air s les increasing by a factor of 3 and 10 after 30 d of storage in conventional 12 mL Exetainers. All tested materials showed a near-linear increase in H2 and CO mixing ratios, indicating a zero-order reaction and material degradation as the underlying cause. Among the rubber materials tested, silicone showed the lowest potential for H2 and CO release. We thus propose modifying Exetainers by closing them with a silicone plug to minimise contamination and sealing them with a stainless-steel bolt and O-ring as a secondary diffusion barrier for long-term storage. Such modified Exetainers exhibited stable mixing ratios of H2 and CH4 exceeding 60 d of storage at atmospheric and elevated (10 ppm) mixing ratios. The increase of CO was still measurable but was 9 times lower than in conventional Exetainers with treated septa this can be corrected for due to its linearity by storing a standard gas alongside the s les. The proposed modification is inexpensive, scalable and robust, and thus it enables reliable storage of large numbers of low-volume gas s les from remote field locations.
Blooms of cyanobacteria in a temperate Australian lagoon system post and prior to European settlement
Publisher: Copernicus GmbH
Date: 25-11-2015
DOI: 10.5194/BGD-12-18829-2015
Abstract: Abstract. Blooms of noxious N2 fixing cyanobacteria such as Nodularia spumigena are a recurring problem in some estuaries. Here we report the results of a palaeoecological study on a temperate Australian lagoon system (The Gippsland Lakes) where we used stable isotopes and pigment biomarkers in dated cores as proxies for eutrophication and blooms of cyanobacteria. Pigment proxies show a clear signal, with an increase in cyanobacterial pigments (echinenone, canthaxanthin and zeaxanthin) in the period coinciding with recent blooms. Another excursion in these proxies was observed prior to the opening of an artificial entrance to the lakes in 1889, which markedly increased the salinity of the Gippsland Lakes. A coincident increase in the sediment organic carbon content in the period prior to the opening of the artificial entrance suggests the bottom waters of the lakes were increasingly stratified and hypoxic, which would have led to an increase in the recycling of phosphorus. After the opening of the artificial entrance there was a ~ 60 year period with low values for the cyanobacterial proxies as well as a low sediment organic carbon content suggesting a period of low bloom activity associated with the increased salinity of the lakes. During the 1940s, the current period of re-eutrophication commenced as indicated by a steadily increasing sediment organic carbon content and cyanobacterial pigments. We suggest increasing nitrogen inputs from the catchment led to the return of hypoxia and increased phosphorus release from the sediment, which drove the re-emergence of cyanobacterial blooms.
Supplementary material to "Negligible isotopic fractionation of nitrogen within temperate <i>Zostera</i> spp. meadows"
Publisher: Copernicus GmbH
Date: 09-04-2018
Nitrogen loads influence trophic organization of estuarine fish assemblages
Publisher: Wiley
Date: 29-02-2016
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
Increased rates of dissimilatory nitrate reduction to ammonium (DNRA) under oxic conditions in a periodically hypoxic estuary
Publisher: Elsevier BV
Date: 05-2014
Factors controlling nitrogen fixation in temperate seagrass beds
Publisher: Inter-Research Science Center
Date: 09-04-2015
DOI: 10.3354/MEPS11247
Environmental controls on the nitrogen-fixing cyanobacterium Nodularia spumigena in a temperate lagoon system in SE Australia
Publisher: Inter-Research Science Center
Date: 28-09-2012
DOI: 10.3354/MEPS09843
The role of bioirrigation in sediment phosphorus dynamics and blooms of toxic cyanobacteria in a temperate lagoon
Publisher: Elsevier BV
Date: 12-2016
The role of alkalinity generation in controlling the fluxes of CO<sub>2</sub> during exposure and inundation on tidal flats
Publisher: Copernicus GmbH
Date: 23-10-2012
Abstract: Abstract. Dissolved inorganic carbon (DIC), gaseous CO2 and alkalinity fluxes from intertidal sediments were investigated during periods of exposure and inundation, using laboratory core incubations, previously published field data and reactive transport model simulations. In the incubations and previous field data, it was found that during periods of alkalinity production (attributed to the accumulation of reduced sulfur species within the sediment), the flux of DIC out of the sediment was greater during inundation than the gaseous CO2 flux during exposure by a factor of up to 1.8. This finding was supported by computational simulations which indicated that large amounts of sulfate reduction and reduced sulfur burial (FeS) induce an alkalinity flux from the sediment during high tide conditions. Model simulations also found that the amount of reactive Fe in the sediment was a major driver of net alkalinity production. Our finding that CO2 fluxes can be significantly lower than total metabolism during exposure has implications for how total metabolism is quantified on tidal flats.
Using sedimentary prokaryotic communities to assess historical changes in the Gippsland Lakes
Publisher: Wiley
Date: 10-10-2023
DOI: 10.1111/FWB.14182
Retention of nitrogen, phosphorus and silicon in a large semi-arid riverine lake system
Publisher: Springer Science and Business Media LLC
Date: 08-11-2010
Evaluation of sustainable electron donors for nitrate removal in different water media
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.WATRES.2015.08.052
Abstract: An external electron donor is usually included in wastewater and groundwater treatment systems to enhance nitrate removal through denitrification. The choice of electron donor is critical for both satisfactory denitrification rates and sustainable long-term performance. Electron donors that are waste products are preferred to pure organic chemicals. Different electron donors have been used to treat different water types and little is known as to whether there are any electron donors that are suitable for multiple applications. Seven different carbon rich waste products, including liquid and solid electron donors, were studied in comparison to pure acetate. Batch-scale tests were used to measure their ability to reduce nitrate concentrations in a pure nutrient solution, light greywater, secondary-treated wastewater and tertiary-treated wastewater. The tested electron donors removed oxidised nitrogen (NOx) at varying rates, ranging from 48 mg N/L/d (acetate) to 0.3 mg N/L/d (hardwood). The concentrations of transient nitrite accumulation also varied across the electron donors. The different water types had an influence on NOx removal rates, the extent of which was dependent on the type of electron donor. Overall, the highest rates were recorded in light greywater, followed by the pure nutrient solution and the two partially treated wastewaters. Cotton wool and rice hulls were found to be promising electron donors with good NOx removal rates, lower leachable nutrients and had the least variation in performance across water types.
Blooms of cyanobacteria in a temperate Australian lagoon system post and prior to European settlement
Publisher: Copernicus GmbH
Date: 22-06-2016
Abstract: Abstract. Blooms of noxious N2 fixing cyanobacteria such as Nodularia spumigena are a recurring problem in some estuaries however, the historic occurrence of such blooms in unclear in many cases. Here we report the results of a palaeoecological study on a temperate Australian lagoon system (the Gippsland Lakes) where we used stable isotopes and pigment biomarkers in dated cores as proxies for eutrophication and blooms of cyanobacteria. Pigment proxies show a clear signal, with an increase in cyanobacterial pigments (echinenone, canthaxanthin and zeaxanthin) in the period coinciding with recent blooms. Another excursion in these proxies was observed prior to the opening of an artificial entrance to the lakes in 1889, which markedly increased the salinity of the Gippsland Lakes. A coincident increase in the sediment organic-carbon content in the period prior to the opening of the artificial entrance suggests that the bottom waters of the lakes were more stratified and hypoxic, which would have led to an increase in the recycling of phosphorus. After the opening of the artificial entrance, there was a ∼ 60-year period with low values for the cyanobacterial proxies as well as a low sediment organic-carbon content suggesting a period of low bloom activity associated with the increased salinity of the lakes. During the 1940s, the current period of re-eutrophication commenced, as indicated by a steadily increasing sediment organic-carbon content and cyanobacterial pigments. We suggest that increasing nitrogen inputs from the catchment led to the return of hypoxia and increased phosphorus release from the sediment, which drove the re-emergence of cyanobacterial blooms.
Presence and survival of culturable Campylobacter spp. and Escherichia coli in a temperate urban estuary
Publisher: Elsevier BV
Date: 11-2016
DOI: 10.1016/J.SCITOTENV.2016.06.195
Abstract: Urban estuaries throughout the world typically contain elevated levels of faecal contamination, the extent of which is generally assessed using faecal indicator organisms (FIO) such as Escherichia coli. This study assesses whether the bacterial FIO, E. coli is a suitable surrogate for C ylobacter spp., in estuaries. The presence and survival dynamics of culturable E. coli and C ylobacter spp. are compared in the water column, bank sediments and bed sediments of the Yarra River estuary (located in Melbourne, Australia). The presence of E. coli did not necessarily indicate detectable levels of C ylobacter spp. in the water column, bed and bank sediments, but the inactivation rates of the two bacteria were similar in the water column. A key finding of the study is that E. coli and C ylobacter spp. can survive for up to 14days in the water column and up to 21days in the bed and bank sediments of the estuary. Preliminary data presented in this study also suggests that the inactivation rates of the two bacteria may be similar in bed and bank sediments. This undermines previous hypotheses that C ylobacter spp. cannot survive outside of its host and indicates that public health risks can persist in aquatic systems for up to three weeks after the initial contamination event.
Nitrogen loads explain primary productivity in estuaries at the ecosystem scale
Publisher: Wiley
Date: 28-07-2015
DOI: 10.1002/LNO.10136
Long-distance electron transport by cable bacteria in mangrove sediments
Publisher: Inter-Research Science Center
Date: 08-03-2016
DOI: 10.3354/MEPS11635
Importance of phytodetritus and microphytobenthos for heterotrophs in a shallow subtidal sandy sediment
Publisher: Inter-Research Science Center
Date: 30-05-2012
DOI: 10.3354/MEPS09676
The Gippsland Lakes: management challenges posed by long-term environmental change
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/MF14222
Abstract: The Gippsland Lakes, listed under the Ramsar Convention in 1982, have undergone chronic salinisation since the cutting in 1889 of an artificial entrance to the ocean to improve navigational access, exacerbated in the mid–late 20th century by increasing regulation and extraction of water from inflowing rivers. Both developments have had substantial ecological impacts: a marked decline in the area of reed (Phragmites australis) beds the loss of salt-intolerant submerged taxa such as Vallisneria australis, causing a shift to a phytoplankton-dominated system in Lake Wellington and, nearer the entrance, an expansion in the area of seagrasses. Mangroves (Avicennia marina) first appeared in the late 1980s or early 1990s. Since 1986 recurring blooms of Nodularia spumigena have led to loss of recreational amenity and to the periodic closure of recreational and commercial fisheries. Changes to hydrological and salinity regimes have almost certainly shifted the contemporary fish community away from the pre-entrance state. Rises in eustatic sea levels and increases in storm surges will exacerbate the issue of chronic salinisation. Whether or not managers choose to intervene to prevent, or at least minimise, ongoing environmental change will inevitably prove controversial, and in some cases no socially or technologically feasible solutions may exist.
Hydrodynamic controls on oxygen dynamics in a riverine salt wedge estuary, the Yarra River estuary, Australia
Publisher: Copernicus GmbH
Date: 10-04-2014
DOI: 10.5194/HESS-18-1397-2014
Abstract: Abstract. Oxygen depletion in coastal and estuarine waters has been increasing rapidly around the globe over the past several decades, leading to decline in water quality and ecological health. In this study we apply a numerical model to understand how salt wedge dynamics, changes in river flow and temperature together control oxygen depletion in a micro-tidal riverine estuary, the Yarra River estuary, Australia. Coupled physical–biogeochemical models have been previously applied to study how hydrodynamics impact upon seasonal hypoxia however, their application to relatively shallow, narrow riverine estuaries with highly transient patterns of river inputs and sporadic periods of oxygen depletion has remained challenging, largely due to difficulty in accurately simulating salt wedge dynamics in morphologically complex areas. In this study we overcome this issue through application of a flexible mesh 3-D hydrodynamic–biogeochemical model in order to predict the extent of salt wedge intrusion and consequent patterns of oxygen depletion. The extent of the salt wedge responded quickly to the sporadic riverine flows, with the strength of stratification and vertical density gradients heavily influenced by morphological features corresponding to shallow points in regions of tight curvature ("horseshoe" bends). The spatiotemporal patterns of stratification led to the emergence of two "hot spots" of anoxia, the first downstream of a shallow region of tight curvature and the second downstream of a sill. Whilst these areas corresponded to regions of intense stratification, it was found that antecedent conditions related to the placement of the salt wedge played a major role in the recovery of anoxic regions following episodic high flow events. Furthermore, whilst a threshold salt wedge intrusion was a requirement for oxygen depletion, analysis of the results allowed us to quantify the effect of temperature in determining the overall severity and extent of hypoxia and anoxia. Climate warming scenarios highlighted that oxygen depletion is likely to be exacerbated through changes in flow regimes and warming temperatures however, the increasing risk of hypoxia and anoxia can be mitigated through management of minimum flow allocations and targeted reductions in organic matter loading. A simple statistical model (R2 0.65) is suggested to relate riverine flow and temperature to the extent of estuary-wide anoxia.
Metabolic flexibility allows bacterial habitat generalists to become dominant in a frequently disturbed ecosystem
Publisher: Springer Science and Business Media LLC
Date: 13-03-2021
DOI: 10.1038/S41396-021-00988-W
Abstract: Ecological theory suggests that habitat disturbance differentially influences distributions of habitat generalist and specialist species. While well-established for macroorganisms, this theory has rarely been explored for microorganisms. Here we tested these principles in permeable (sandy) sediments, ecosystems with much spatiotemporal variation in resource availability and physicochemical conditions. Microbial community composition and function were profiled in intertidal and subtidal sediments using 16S rRNA gene licon sequencing and metagenomics, yielding 135 metagenome-assembled genomes. Community composition and metabolic traits modestly varied with sediment depth and s ling date. Several taxa were highly abundant and prevalent in all s les, including within the orders Woeseiales and Flavobacteriales, and classified as habitat generalists genome reconstructions indicate these taxa are highly metabolically flexible facultative anaerobes and adapt to resource variability by using different electron donors and acceptors. In contrast, obligately anaerobic taxa such as sulfate reducers and candidate lineage MBNT15 were less abundant overall and only thrived in more stable deeper sediments. We substantiated these findings by measuring three metabolic processes in these sediments whereas the habitat generalist-associated processes of sulfide oxidation and fermentation occurred rapidly at all depths, the specialist-associated process of sulfate reduction was restricted to deeper sediments. A manipulative experiment also confirmed habitat generalists outcompete specialist taxa during simulated habitat disturbance. Together, these findings show metabolically flexible habitat generalists become dominant in highly dynamic environments, whereas metabolically constrained specialists are restricted to narrower niches. Thus, an ecological theory describing distribution patterns for macroorganisms likely extends to microorganisms. Such findings have broad ecological and biogeochemical ramifications.
Catchment land use predicts benthic vegetation in small estuaries
Publisher: PeerJ
Date: 14-02-2018
DOI: 10.7717/PEERJ.4378
Abstract: Many estuaries are becoming increasingly eutrophic from human activities within their catchments. Nutrient loads often are used to assess risk of eutrophication to estuaries, but such data are expensive and time consuming to obtain. We compared the percent of fertilized land within a catchment, dissolved inorganic nitrogen loads, catchment to estuary area ratio and flushing time as predictors of the proportion of macroalgae to total vegetation within 14 estuaries in south-eastern Australia. The percent of fertilized land within the catchment was the best predictor of the proportion of macroalgae within the estuaries studied. There was a transition to a dominance of macroalgae once the proportion of fertilized land in the catchment exceeded 24%, highlighting the sensitivity of estuaries to catchment land use.
Transport and degradation of a dinoflagellate bloom in permeable sublittoral sediment
Publisher: Inter-Research Science Center
Date: 2007
DOI: 10.3354/MEPS340139
Tracing carbon and nitrogen incorporation and pathways in the microbial community of a photic subtidal sand
Publisher: Inter-Research Science Center
Date: 26-11-2008
DOI: 10.3354/AME01248
Adapting Urban Water Systems to a Changing Climate: Lessons from the Millennium Drought in Southeast Australia
Publisher: American Chemical Society (ACS)
Date: 15-05-2013
DOI: 10.1021/ES400618Z
Capacity of a temperate intertidal seagrass species to tolerate changing environmental conditions: Significance of light and tidal exposure
Publisher: Elsevier BV
Date: 10-2017
Escherichia coli survival and transfer in estuarine bed sediments
Publisher: Wiley
Date: 03-05-2018
DOI: 10.1002/RRA.3281
Biofilter design for effective nitrogen removal from stormwater - influence of plant species, inflow hydrology and use of a saturated zone
Publisher: IWA Publishing
Date: 21-01-2014
DOI: 10.2166/WST.2014.013
Abstract: The use of biofilters to remove nitrogen and other pollutants from urban stormwater runoff has demonstrated varied success across laboratory and field studies. Design variables including plant species and use of a saturated zone have large impacts upon performance. A laboratory column study of 22 plant species and designs with varied outlet configuration was conducted across a 1.5-year period to further investigate the mechanisms and influences driving biofilter nitrogen processing. This paper presents outflow concentrations of total nitrogen from two s ling events across both ‘wet’ and ‘dry’ frequency dosing, and from s ling across two points in the outflow hydrograph. All plant species were effective under conditions of frequent dosing, but extended drying increased variation between species and highlighted the importance of a saturated zone in maintaining biofilter function. The saturated zone also effectively treated the volume of stormwater stored between inflow events, but this extended detention provided no additional benefit alongside the rapid processing of the highest performing species. Hence, the saturated zone reduced performance differences between plant species, and potentially acts as an ‘insurance policy’ against poor sub-optimal plant selection. The study shows the importance of bio ersity and inclusion of a saturated zone in protecting against climate variability.
Sources and fate of nitrate in a groundwater‐fed estuary elucidated using stable isotope ratios of nitrogen and oxygen
Publisher: Wiley
Date: 03-08-2014
Dynamics of groundwater‐derived nitrate and nitrous oxide in a tidal estuary from radon mass balance modeling
Publisher: Wiley
Date: 27-08-2013
Benthic fluxes of nitrogen in the tidal reaches of a turbid, high-nitrate sub-tropical river
Publisher: Elsevier BV
Date: 04-2004
Negligible isotopic fractionation of nitrogen within temperate <i>Zostera</i> spp. meadows
Publisher: Copernicus GmbH
Date: 09-04-2018
DOI: 10.5194/BG-2018-154
Abstract: Abstract. Seagrass meadows form an ecologically important ecosystem in the coastal zone. Excessive nitrogen inputs to the coastal zone pose a key threat to seagrass through eutrophication and associated algal overgrowth. The 15N / 14N ratio of seagrass is commonly used to assess extent to which sewage derived nitrogen may be influencing seagrass beds. There have however, been no studies comparing the 15N / 14N ratios of seagrass beds, their associated sediments and of critical importance, the porewater NH4+ pool, which is most bioavailable. Here, we undertook a study of the 15N / 14N ratios of seagrass tissue, sediment porewater NH4+ pool and the sediment solid phase to elucidate the extent of any fractionating processes taking place during organic matter mineralisation and nitrogen assimilation. The study was undertaken within two coastal embayments known to receive nitrogen from a range of sources including marine, urban and sewage sources. The δ15N of porewater ammonium was strongly correlated with the δ15N of both the sediment solid phase and seagrass tissue (r2 of 0.89 and 0.85) respectively. The δ15N porewater NH4+ minus the δ15N seagrass tissue ranged between −1.4 and 7 ‰ with an average 1.6 ‰. We suggest the most likely explanation for this was fractionation during assimilation as a consequence of diffusion limitation, although the magnitude of this change was relatively small. Nitrogen fixation may have also contributed a small amount to the observed isotopic depletion of the plants relative to the sediment porewater NH4+ pool. A consideration of the nitrogen isotope values of the seagrass bed nitrogen pools compared to external sources suggest the dominant source of nitrogen to seagrass is recycling from within the bed, with a relatively small contribution from water column assimilation, particulate trapping and nitrogen fixation.
The influence of an invasive plant on denitrification in an urban wetland
Publisher: Wiley
Date: 08-02-2018
DOI: 10.1111/FWB.13073
Tracing carbon sources in small urbanising streams: Catchment-scale stormwater drainage overwhelms the effects of reach-scale riparian vegetation
Publisher: Wiley
Date: 18-10-2014
DOI: 10.1111/FWB.12256
Designing living walls for greywater treatment
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.WATRES.2016.12.018
Abstract: Greywater is being increasingly used as an alternative water source to reduce potable water demand and to alleviate pressure on sewerage systems. This paper presents the development of a low energy and low maintenance greywater treatment technology: a living wall system, employing ornamental plants (including vines) grown in a sand filter on a side of a building to treat shower, bath, and washing basin wastewaters. The system can, at the same time, provide critical amenity and micro-climate benefits to our cities. A large scale column study was conducted in Melbourne, Australia, to investigate the following design and operational factors of the proposed system: plant species, saturated zone design, rest period, hydraulic loading rate and pollutant inflow concentration. The results indicate that the use of ornamental species (e.g. Canna lilies, Lonicera japonica, ornamental grape vine) can contribute to pollutant removal. Vegetation selection was found to be particularly important for nutrient removal. While a wider range of tested plant species was effective for nitrogen removal (>80%), phosphorus removal was more variable (-13% to 99%) over the study period, with only a few tested plants being effective - Carex appressa and Canna lilies were the best performers. It was also found that phosphorus removal can be compromised over the longer term as a result of leaching. Excellent suspended solids and organics removal efficiencies can be generally achieved in these systems (>80% for TSS and >90% for BOD) with plants having a relatively small impact. Columns had an acceptable infiltration capacity after one year of operation. When planted with effective species (e.g. Carex appressa and Canna lilies), it is expected that performance will not be significantly affected by longer rest periods and higher pollutant concentrations in the early years of system operation. The results of this study, thus, demonstrate that innovative and aesthetically pleasing living walls can be designed for treatment of greywater at the household scale.
Stable isotopes of nitrate reveal different nitrogen processing mechanisms in streams across a land use gradient during wet and dry periods
Publisher: Copernicus GmbH
Date: 04-10-2017
DOI: 10.5194/BG-2017-240
Abstract: Abstract. Understanding the relationship between land use and the dynamics of nitrate (NO3−) is the key to constrain sources of NO3− export in order to aid effective management of waterways. In this study, isotopic compositions of NO3− (δ15N-NO3− and δ18O-NO3−) were used to elucidate the effects of land use (agriculture in particular) and rainfall on the major sources and sinks of NO3− within the Westernport catchment, Victoria, Australia. This study is one of the very few studies carried out in temperate regions with highly stochastic rainfall patterns enabling a more comprehensive understanding of the applications of NO3− isotopes in catchment ecosystems with different climatic conditions. Longitudinal s les were collected from five streams with different agriculture land use intensities on five occasions – three during dry periods and two during wet periods. At the catchment scale, we observed significant positive relationships between NO3− concentrations, δ15N-NO3− and percentage agriculture reflecting the dominance of anthropogenic nitrogen inputs within the catchment. Different rainfall conditions appeared to be major controls on the predominance of the sources and transformation processes of NO3− in our study sites. Artificial fertiliser was the dominant source of NO3− during the wet periods while nitrified organic matter in sediment and nitrified manure were more apparent sources of NO3− to the surface water during the dry periods. Denitrification was prevalent during the wet periods while uptake of NO3− by plants or algae was only observed during the dry periods in two streams. The outcome of this study suggests that effective reduction of NO3− load to the streams can only be achieved by prioritising management strategies based on different rainfall conditions.
Hyporheic hot moments: Dissolved oxygen dynamics in the hyporheic zone in response to surface flow perturbations
Publisher: American Geophysical Union (AGU)
Date: 08-2017
DOI: 10.1002/2016WR020296
Metabolism in anoxic permeable sediments is dominated by eukaryotic dark fermentation
Publisher: Springer Science and Business Media LLC
Date: 28-11-2017
DOI: 10.1038/NGEO2843
Does denitrification occur within porous carbonate sand grains?
Publisher: Copernicus GmbH
Date: 19-09-2017
Abstract: Abstract. Permeable carbonate sands form a major habitat type on coral reefs and play a major role in organic matter recycling. Nitrogen cycling within these sediments is likely to play a major role in coral reef productivity, yet it remains poorly studied. Here, we used flow-through reactors and stirred reactors to quantify potential rates of denitrification and the dependence of denitrification on oxygen concentrations in permeable carbonate sands at three sites on Heron Island, Australia. Our results showed that potential rates of denitrification fell within the range of 2–28 µmol L−1 sediment h−1 and were very low compared to oxygen consumption rates, consistent with previous studies of silicate sands. Denitrification was observed to commence at porewater oxygen concentrations as high as 50 µM in stirred reactor experiments on the coarse sediment fraction (2–10 mm) and at oxygen concentrations of 10–20 µM in flow-through and stirred reactor experiments at a site with a median sediment grain size of 0.9 mm. No denitrification was detected in sediments under oxic conditions from another site with finer sediment (median grain size: 0.7 mm). We interpret these results as confirmation that denitrification may occur within anoxic microniches present within porous carbonate sand grains. The occurrence of such microniches has the potential to enhance denitrification rates within carbonate sediments however further work is required to elucidate the extent and ecological significance of this effect.
Temporary Storage or Permanent Removal? The Division of Nitrogen between Biotic Assimilation and Denitrification in Stormwater Biofiltration Systems
Publisher: Public Library of Science (PLoS)
Date: 26-03-2014
Recovery of denitrification and dissimilatory nitrate reduction to ammonium following reoxygenation of sediments from a periodically hypoxic temperate lagoon
Publisher: Wiley
Date: 21-06-2022
DOI: 10.1002/LNO.12173
Abstract: Eutrophication and stratification events have increased the incidences of hypoxia and anoxia in coastal environments. The depletion of oxygen in these environments can lead to a shift in biogeochemical processes such as denitrification and dissimilatory nitrate reduction to ammonium (DNRA). The balance between denitrification and DNRA is critical because denitrification leads to a loss of bioavailable nitrogen and DNRA maintains it within the system. This study examined the effects of reoxygenation on denitrification and DNRA in sediments collected from a periodically hypoxic system (Gippsland Lakes, Australia) and subjected to experimental hypoxia using a modified 15 N‐isotope pairing technique. For freshly collected sediments, the ratio of denitrification : DNRA was generally 1 indicating a dominance of DNRA. After 3–4 weeks of oxygenation, denitrification increased relative to DNRA resulting in a denitrification : DNRA ratio 1. Profiles of 15 N‐N 2 and accumulation in these experiments showed denitrification and DNRA generally only took place in the surface ~ 2 cm of sediment. Prolonged experiments with reoxygenated sediments showed a decrease in the denitrification : DNRA to 1 after 56 d coincident with deep accumulation of within the sediment (2–5 cm) suggesting faunal irrigation enhanced DNRA deep in the sediment. An experiment with bromide tracer confirmed the occurrence of DNRA deep within the sediment at 2–6 cm was coincident with tracer penetration, and there was a significant positive relationship between bioirrigation and DNRA. We suggest DNRA deep within the sediment was enhanced by increased availability of organic carbon, reduced solutes, and possibly exposure of reworked sediment to .
Inside Story of Gas Processes within Stormwater Biofilters: Does Greenhouse Gas Production Tarnish the Benefits of Nitrogen Removal?
Publisher: American Chemical Society (ACS)
Date: 24-03-2017
Abstract: Stormwater biofilters are dynamic environments, supporting erse processes that act to capture and transform incoming pollutants. However, beneficial water treatment processes can be accompanied by undesirable greenhouse gas production. This study investigated the potential for nitrous oxide (N
Understanding the seagrass‐sediment‐light feedback to guide restoration planning: a case study using Zostera muelleri
Publisher: Wiley
Date: 24-10-2023
DOI: 10.1111/REC.14044
Effect of nutrient availability on carbon and nitrogen incorporation and flows through benthic algae and bacteria in near-shore sandy sediment
Publisher: Inter-Research Science Center
Date: 15-11-2007
DOI: 10.3354/AME01142
Constraining nitrogen sources to a seagrass-dominated coastal embayment by using an isotope mass balance approach
Publisher: CSIRO Publishing
Date: 25-02-2022
DOI: 10.1071/MF21320
Abstract: Nitrogen (N) is often the key nutrient limiting primary production in coastal waters. Quantifying sources and sinks of N is therefore critical to understanding the factors that underpin the productivity of coastal ecosystems. Constraining nitrogen inputs can be difficult for some terms such as N fixation and marine exchange as a consequence of uncertainties associated with scaling and stochasticity. To help overcome these issues, we undertook a N budget incorporating an isotope and mass balance to constrain N sources in a large oligotrophic coastal embayment (Western Port, Australia). The total N input to Western Port was calculated to be 1400 Mg N year−1, which is remarkably consistent with previous estimates of sedimentation rates within the system. Catchment inputs, N fixation, marine sources and atmospheric deposition comprised 44, 28, 28 and 13% of N inputs respectively. Retention of marine-derived N equated to ~3 and ~10% of total N and NOx flushed through the system from the marine end-member. The relatively high contribution of N fixation compared with previous studies was most likely to be due to the high proportion of nutrient-limited intertidal sediments where N is mediated by seagrasses and sediment cyanobacteria.
Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon
Publisher: Copernicus GmbH
Date: 06-10-2017
Abstract: Abstract. The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) were investigated using a 3-D coupled hydrodynamic biogeochemical water quality model. The study showed that primary production was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment were the main drivers for the hypoxia and subsequent sediment phosphorus release in Lake King. High primary production stimulated by large nitrogen loading brought on by a winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads), which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both total nitrogen and total phosphorus for water quality improvement in estuarine systems.
Ambient groundwater flow diminishes nitrate processing in the hyporheic zone of streams
Publisher: American Geophysical Union (AGU)
Date: 05-2017
DOI: 10.1002/2016WR020048
Co-optimisation of phosphorus and nitrogen removal in stormwater biofilters: The role of filter media, vegetation and saturated zone
Publisher: IWA Publishing
Date: 06-03-2014
DOI: 10.2166/WST.2014.117
Abstract: Biofilters have been shown to effectively treat stormwater and achieve nutrient load reduction targets. However, effluent concentrations of nitrogen and phosphorus typically exceed environmental targets for receiving water protection. This study investigates the role of filter media, vegetation and a saturated zone (SZ) in achieving co-optimised nitrogen and phosphorus removal in biofilters. Twenty biofilter columns were monitored over a 12-month period of dosing with semi-synthetic stormwater. The frequency of dosing was altered seasonally to examine the impact of hydrologic variability. Very good nutrient removal (90% total phosphorus, 89% total nitrogen) could be achieved by incorporating vegetation, an SZ and Skye sand, a naturally occurring iron-rich filter medium. This design maintained nutrient removal at or below water quality guideline concentrations throughout the experiment, demonstrating resilience to wetting–drying fluctuations. The results also highlighted the benefit of including an SZ to maintain treatment performance over extended dry periods. These findings represent progress towards designing biofilters which co-optimise nitrogen and phosphorus removal and comply with water quality guidelines.
Fe and S K-edge XAS determination of iron-sulfur species present in a range of acid sulfate soils: Effects of particle size and concentration on quantitative XANES determinations
Publisher: IOP Publishing
Date: 11-2009
The kinetics of denitrification in permeable sediments
Publisher: Springer Science and Business Media LLC
Date: 09-09-2012
Unravelling the origin and fate of nitrate in an agricultural–urban coastal aquifer
Publisher: Springer Science and Business Media LLC
Date: 16-10-2014
Supplementary material to "Technical Note: Inexpensive modification of Exetainers for the reliable storage of trace-level hydrogen and carbon monoxide gas samples"
Publisher: Copernicus GmbH
Date: 21-09-2020
Long term nutrient loads and chlorophyll dynamics in a large temperate Australian lagoon system affected by recurring blooms of cyanobacteria
Publisher: Springer Science and Business Media LLC
Date: 12-2010
Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon
Publisher: Copernicus GmbH
Date: 11-04-2017
DOI: 10.5194/BG-2017-132
Abstract: Abstract. The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) was investigated using a 3D coupled hydrodynamic biogeochemical water quality model. The study showed that primary productivity was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment are the main drivers for the hypoxia and subsequent sediment phosphorus release in the Lake King. High primary production stimulated by large nitrogen loading brought by winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads) which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both TN and TP for water quality improvement in estuarine systems.
Carbon and nitrogen cycling on intertidal mudflats of a temperate Australian estuary. IV. Inverse model analysis and synthesis
Publisher: Inter-Research Science Center
Date: 18-11-2009
DOI: 10.3354/MEPS08270
Controls on oxygen dynamics in a riverine salt-wedge estuary – a three-dimensional model of the Yarra River estuary, Australia
Publisher: Copernicus GmbH
Date: 24-09-2021
DOI: 10.5194/HESSD-10-9799-2013
Abstract: Abstract. Oxygen depletion in estuarine waters is an important factor governing water quality and ecological health. A complex and dynamic balance of physical and biogeochemical factors drive the extent and persistence of hypoxia and anoxia making it difficult to predict. An increased understanding of the effect of changing flow regimes and temperature on patterns of estuarine oxygen depletion is required to support ongoing management. Coupled physical and biogeochemical models have been applied to study the interaction of physical processes and seasonal hypoxia, however, application to riverine estuaries with tight curvature and more sporadic periods of oxygen depletion is rare. In this study we apply a finite volume 3-D hydrodynamic-biogeochemical model (TUFLOW-FV–FABM) to the Yarra River estuary, Australia, in order to predict the extent of salt-wedge intrusion and consequent patterns of oxygen depletion. The predictive capacity of the model was evaluated using a series of model verification metrics and the results evaluated to determine the dominant mechanisms affecting salt-wedge position and the extent and persistence of anoxia and hypoxia. Measures of model fit indicated that the model reasonably captured the strength of stratification and the position and extent of the salt wedge (r2 ~ 0.74). The extent of the salt wedge intrusion was controlled by riverine flow and the strength of stratification or mixing dominated by topographical features corresponding to areas of tight curvature ("horseshoe" bends). The model predicted that the extent of anoxic waters generally mimicked the extent of the salt wedge (r2 ~ 0.65) increasing during periods of low flow and reduced following episodic high flow events. The results showed two sporadically isolated "hot spots" of anoxia, the first downstream of the horseshoe bend and the second downstream of a sill. Simulated oxygen concentrations indicated that whilst a threshold salt wedge intrusion was a requirement of oxygen depletion, temperature was critical in determining the extent of hypoxia and anoxia in the estuary. These findings highlight the importance of how seasonal changes in flow events and environmental flow management can impact on estuarine oxygen depletion in a warming climate. This study provides an improved understanding of the controls on hypoxia and anoxia in riverine estuaries, which is essential to support improved prediction of nutrient dynamics and ecological heath.
Molecular hydrogen in seawater supports growth of diverse marine bacteria
Publisher: Springer Science and Business Media LLC
Date: 06-02-2023
DOI: 10.1038/S41564-023-01322-0
Abstract: Molecular hydrogen (H 2 ) is an abundant and readily accessible energy source in marine systems, but it remains unknown whether marine microbial communities consume this gas. Here we use a suite of approaches to show that marine bacteria consume H 2 to support growth. Genes for H 2 -uptake hydrogenases are prevalent in global ocean metagenomes, highly expressed in metatranscriptomes and found across eight bacterial phyla. Capacity for H 2 oxidation increases with depth and decreases with oxygen concentration, suggesting that H 2 is important in environments with low primary production. Biogeochemical measurements of tropical, temperate and subantarctic waters, and axenic cultures show that marine microbes consume H 2 supplied at environmentally relevant concentrations, yielding enough cell-specific power to support growth in bacteria with low energy requirements. Conversely, our results indicate that oxidation of carbon monoxide (CO) primarily supports survival. Altogether, H 2 is a notable energy source for marine bacteria and may influence oceanic ecology and biogeochemistry.
Pollution‐tolerant invertebrates enhance greenhouse gas flux in urban wetlands
Publisher: Wiley
Date: 12-07-2017
DOI: 10.1002/EAP.1572
Abstract: One of the goals of urban ecology is to link community structure to ecosystem function in urban habitats. Pollution-tolerant wetland invertebrates have been shown to enhance greenhouse gas (GHG) flux in controlled laboratory experiments, suggesting that they may influence urban wetland roles as sources or sinks of GHG. However, it is unclear if their effects can be detected in highly variable conditions in a field setting. Here we use an extensive data set on carbon dioxide (CO
Deep dynamic pools of phosphorus in the sediment of a temperate lagoon with recurring blooms of diazotrophic cyanobacteria
Publisher: Wiley
Date: 10-09-2015
DOI: 10.1002/LNO.10162
Bedforms as Biocatalytic Filters: A Pumping and Streamline Segregation Model for Nitrate Removal in Permeable Sediments
Publisher: American Chemical Society (ACS)
Date: 27-08-2015
Abstract: Bedforms are a focal point of carbon and nitrogen cycling in streams and coastal marine ecosystems. In this paper, we develop and test a mechanistic model, the "pumping and streamline segregation" or PASS model, for nitrate removal in bedforms. The PASS model dramatically reduces computational overhead associated with modeling nitrogen transformations in bedforms and reproduces (within a factor of 2 or better) previously published measurements and models of biogeochemical reaction rates, benthic fluxes, and in-sediment nutrient and oxygen concentrations. Application of the PASS model to a erse set of marine and freshwater environments indicates that (1) physical controls on nitrate removal in a bedform include the pore water flushing rate, residence time distribution, and relative rates of respiration and transport (as represented by the Damkohler number) (2) the biogeochemical pathway for nitrate removal is an environment-specific combination of direct denitrification of stream nitrate and coupled nitrification-denitrification of stream and/or sediment ammonium and (3) permeable sediments are almost always a net source of dissolved inorganic nitrogen. The PASS model also provides a mechanistic explanation for previously published empirical correlations showing denitrification velocity (N2 flux ided by nitrate concentration) declines as a power law of nitrate concentration in a stream (Mulholland et al. Nature, 2008, 452, 202-205).
Transport Zonation Limits Coupled Nitrification-Denitrification in Permeable Sediments
Publisher: American Chemical Society (ACS)
Date: 21-11-2013
DOI: 10.1021/ES403318X
Abstract: Measurement of biogeochemical processes in permeable sediments (including the hyporheic zone) is difficult because of complex multidimensional advective transport. This is especially the case for nitrogen cycling, which involves several coupled redox-sensitive reactions. To provide detailed insight into the coupling between ammonification, nitrification and denitrification in stationary sand ripples, we combined the diffusion equilibrium thin layer (DET) gel technique with a computational reactive transport biogeochemical model. The former approach provided high-resolution two-dimensional distributions of NO3(-) and (15)N-N2 gas. The measured two-dimensional profiles correlate with computational model simulations, showing a deep pool of N2 gas forming, and being advected to the surface below ripple peaks. Further isotope pairing calculations on these data indicate that coupled nitrification-denitrification is severely limited in permeable sediments because the flow and transport field limits interaction between oxic and anoxic pore water. The approach allowed for new detailed insight into subsurface denitrification zones in complex permeable sediments.
Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study
Publisher: Springer Science and Business Media LLC
Date: 08-09-2016
Stable isotopes of nitrate reveal different nitrogen processing mechanisms in streams across a land use gradient during wet and dry periods
Publisher: Copernicus GmbH
Date: 02-07-2018
Abstract: Abstract. Understanding the relationship between land use and the dynamics of nitrate (NO3-) is the key to constrain sources of NO3- export in order to aid effective management of waterways. In this study, isotopic compositions of NO3- (δ15N–NO3- and δ18O–NO3-) were used to elucidate the effects of land use (agriculture in particular) and rainfall on the major sources and sinks of NO3- within the Western Port catchment, Victoria, Australia. This study is one of the very few studies carried out in temperate regions with highly stochastic rainfall patterns, enabling a more comprehensive understanding of the applications of NO3- isotopes in catchment ecosystems with different climatic conditions. Longitudinal s les were collected from five streams with different agriculture land use intensities on five occasions – three during dry periods and two during wet periods. At the catchment scale, we observed significant positive relationships between NO3- concentrations (p 0.05), δ15N–NO3- (p 0.01) and percentage agriculture (particularly during the wet period), reflecting the dominance of anthropogenic nitrogen inputs within the catchment. Different rainfall conditions appeared to be major controls on the predominance of the sources and transformation processes of NO3- in our study sites. Artificial fertiliser was the dominant source of NO3- during the wet periods. In addition to artificial fertiliser, nitrified organic matter in sediment was also an apparent source of NO3- to the surface water during the dry periods. Denitrification was prevalent during the wet periods, while uptake of NO3- by plants or algae was only observed during the dry periods in two streams. The outcome of this study suggests that effective reduction of NO3- load to the streams can only be achieved by prioritising management strategies based on different rainfall conditions.
Speciation of dissolved iodine in the waters of a humic-rich estuary
Publisher: Elsevier BV
Date: 04-2000
The importance of nitrogen fixation to a temperate, intertidal embayment determined using a stable isotope mass balance approach
Publisher: Copernicus GmbH
Date: 27-11-2017
DOI: 10.5194/BG-2017-418
Abstract: Abstract. The balance between denitrification and nitrogen fixation is the key control of the availability of nitrogen in coastal ecosystems and thus the primary productivity of these environments. However, evaluating the importance of denitrification and nitrogen fixation over large spatial and temporal scales is problematic. In this study, a combined mass and stable isotope balance of nitrogen was used to constrain the cycling of nitrogen in Western Port, Victoria – a temperate, intertidal embayment in south-eastern Australia. This method is a more effective approach compared to the extrapolation of discrete measurements and geochemical approaches. The validity of the isotope and mass balance model has been tested by comparing the output of the model with the average measured isotopic signature of the sediment in Western Port. Using previously measured rates of nitrogen fixation and denitrification in combination with the isotopic signature of nitrogen inputs from the catchment, atmosphere and the marine environment, the model returned an isotopic signature of 4.1 ± 2.5 ‰. This compares favorably with the average measured isotopic signature of the sediment of 3.9 ± 1.2 ‰. Sensitivity analysis confirmed that it was the isotopic values of the end-members, fractionation factors of assimilation and denitrification that exerted the greatest control over the isotopic signature of the sediment and not the loadings of the source and sink terms. Analysis of the relative importance of the various nitrogen inputs into the bay suggests that nitrogen fixation contributes 36 % of the total nitrogen inputs to Western Port.
Using stable isotope ratios to estimate atmospheric nitrogen fixed by cyanobacteria at the ecosystem scale
Publisher: Wiley
Date: 04-2014
DOI: 10.1890/13-0947.1
Abstract: Diazotrophic cyanobacteria are capable of fixing atmospheric N2 to satisfy their physiological nitrogen requirements. This process can result in the transfer of substantial amounts of "new" diazotrophic nitrogen (ND) to aquatic ecosystems during blooms of these taxa. Using in situ measurements of plankton natural abundance stable isotope composition and a combination of underway and fixed site survey data, the total N(D) flux into the Gippsland Lakes estuary (Australia) was estimated during a summer bloom of the diazotrophic cyanobacterium Nodularia spumigena. Over the course of the bloom, N(D) increased in the upper water column of the estuary from 33% +/- 17% (mean +/- SD) to 73% +/- 13% of the standing pool of total particulate N. A conservative estimate of total N(D) flux (146 Mg) equates to an estimated 177% of the summer total N load and 22% of the annual total N load to the estuary. Combining natural abundance stable isotope measurements with relatively simple fixed and underway survey designs can provide a cost-effective approach for monitoring the N(D) flux into estuary or lacustrine environments. This approach relies on an isotopic differential between the diazotrophic and the non-diazotrophic components of the plankton community it may not be appropriate in ecosystems that experience low-level blooms or blooms of intermittent N-fixing cyanobacteria. Large-scale blooms of diazotrophic cyanobacteria are considered uncommon in estuaries, yet it is clear that these blooms can represent major sources of new N to estuarine ecosystems when and where they occur.
Enhancement of denitrification in permeable carbonate sediment due to intra-granular porosity: A multi-scale modelling analysis
Publisher: Elsevier BV
Date: 09-2014
Testing assumptions of the eukaryotic inhibitor method for investigating interactions between aquatic protozoa and bacteria, applied to marine sediment
Publisher: Wiley
Date: 07-2011
Technical Note: Inexpensive modification of Exetainers for the reliable storage of trace-level hydrogen and carbon monoxide gas samples
Publisher: Copernicus GmbH
Date: 21-09-2020
DOI: 10.5194/BG-2020-282
Abstract: Abstract. Atmospheric trace gases such as dihydrogen (H2), carbon monoxide (CO) and methane (CH4) play important roles in microbial metabolism and biogeochemical cycles. Analysis of these gases at trace levels requires reliable storage of discrete s les of low volume. While commercial s ling vials such as Exetainers® have been tested for CH4 and other greenhouse gases, no information on reliable storage is available for H2 and CO. We show that vials sealed with butyl rubber stoppers are not suitable for storing H2 and CO due to release of these gases from rubber material. Treating butyl septa with NaOH reduced trace gas release, but contamination was still substantial, with H2 and CO concentrations in air s les increasing by a factor of 3 and 10 after 30 days of storage in conventional 12 mL Exetainers. Among the rubber materials tested, silicone showed the lowest potential for H2 and CO release. We thus propose to modify Exetainers by closing them with a silicone plug, and sealing them with a stainless steel bolt and O-ring for long-term storage. Such modified Exetainers exhibited stable concentrations of H2 and CH4 exceeding 60 days of storage at atmospheric and elevated (10 ppm) concentrations. The increase of CO was still measurable, but nine times lower than in conventional Exetainers with treated septa, and can be corrected for due to its linearity by storing a standard gas alongside the s les. The proposed modification is inexpensive, scalable and robust, and thus enables reliable storage of large numbers of low-volume gas s les from remote field locations.
Phosphorus Fate and Dynamics in Greywater Biofiltration Systems.
Publisher: American Chemical Society (ACS)
Date: 31-01-2017
Abstract: Phosphorus, a critical environmental pollutant, is effectively removed from stormwater by biofiltration systems, mainly via sedimentation and straining. However, the fate of dissolved inflow phosphorus concentrations in these systems is unknown. Given the growing interest in using biofiltration systems to treat other polluted waters, for ex le greywater, such an understanding is imperative to optimize designs for successful long-term performance. A mass balance method and a radiotracer,
Trace gas oxidizers are widespread and active members of soil microbial communities
Publisher: Springer Science and Business Media LLC
Date: 04-01-2021
DOI: 10.1038/S41564-020-00811-W
Abstract: Soil microorganisms globally are thought to be sustained primarily by organic carbon sources. Certain bacteria also consume inorganic energy sources such as trace gases, but they are presumed to be rare community members, except within some oligotrophic soils. Here we combined metagenomic, biogeochemical and modelling approaches to determine how soil microbial communities meet energy and carbon needs. Analysis of 40 metagenomes and 757 derived genomes indicated that over 70% of soil bacterial taxa encode enzymes to consume inorganic energy sources. Bacteria from 19 phyla encoded enzymes to use the trace gases hydrogen and carbon monoxide as supplemental electron donors for aerobic respiration. In addition, we identified a fourth phylum (Gemmatimonadota) potentially capable of aerobic methanotrophy. Consistent with the metagenomic profiling, communities within soil profiles from erse habitats rapidly oxidized hydrogen, carbon monoxide and to a lesser extent methane below atmospheric concentrations. Thermodynamic modelling indicated that the power generated by oxidation of these three gases is sufficient to meet the maintenance needs of the bacterial cells capable of consuming them. Diverse bacteria also encode enzymes to use trace gases as electron donors to support carbon fixation. Altogether, these findings indicate that trace gas oxidation confers a major selective advantage in soil ecosystems, where availability of preferred organic substrates limits microbial growth. The observation that inorganic energy sources may sustain most soil bacteria also has broad implications for understanding atmospheric chemistry and microbial bio ersity in a changing world.
Effect of a flood event on the dynamics of phytoplankton and biogeochemistry in a large temperate Australian lagoon
Publisher: Wiley
Date: 15-03-2010
Development of a gas diffusion probe for the rapid measurement of pCO2 in aquatic samples
Publisher: Elsevier BV
Date: 04-2011
DOI: 10.1016/J.ACA.2011.02.024
Abstract: A probe for the direct measurement of the partial pressure of carbon dioxide (pCO(2)) in aqueous s les is described. It consists of a gas permeable membrane tube containing a flowing acceptor stream of bromothymol blue indicator solution. Carbon dioxide diffuses across the membrane causing a pH change in the acceptor. This pH change decreases the absorbance of the acid-base indicator which is detected photometrically, with high sensitivity using a multi-reflection photometric detector with an LED light source. Unlike many other common methods used to measure pCO(2), this probe has the advantage of not requiring s ling to perform measurements, and avoids potential losses and contamination. This probe has the potential to perform experiments requiring in situ measurements of pCO(2), allowing regular measurements of closed system experiments, without removing any of the water column. Compared to indirect methods used to measure pCO(2), this probe has the potential to provide more portable and faster measurements. The sensitivity, s ling rate and linear range of the probe can be tuned depending on the required sensitivity and range of measurements, and a measurement rate of at least 36 h(-1) can be achieved. An application of this probe in real-time analysis of pCO(2) flux in a sediment core during a large deposition of organic matter has been described. As a comparison, the measurements of the probe have been plotted against pCO(2) calculated from alkalinity using a Gran titration. It is envisaged that the probe could be used for experiments in the laboratory requiring real time in situ measurements, or incorporated into a portable instrument so that field measurements can be easily performed. Although the linear range and sensitivity of this probe can be tuned, the configuration described gave a linear response over the calibration range of 0-5800 μatm pCO(2), with a detection limit of 144 μatm. The precision was 1.2% RSD (n=13) at 430 μatm.
Correction to Transport Zonation Limits Coupled Nitrification-Denitrification in Permeable Sediments
Publisher: American Chemical Society (ACS)
Date: 22-05-2014
DOI: 10.1021/ES502359A
Hyporheic flow and dissolved oxygen distribution in fish nests: The effects of open channel velocity, permeability patterns, and groundwater upwelling
Publisher: American Geophysical Union (AGU)
Date: 12-2016
DOI: 10.1002/2016JG003381
Nitrogen Removal in Greywater Living Walls: Insights into the Governing Mechanisms
Publisher: MDPI AG
Date: 23-04-2018
DOI: 10.3390/W10040527
Plant-Microbe Interactions Drive Denitrification Rates, Dissolved Nitrogen Removal, and the Abundance of Denitrification Genes in Stormwater Control Measures
Publisher: American Chemical Society (ACS)
Date: 30-07-2018
Abstract: The microbial community and function along with nitrate/nitrite (NOx) removal rates, and nitrogen (N) partitioning into "uptake", "denitrification", and "remaining" via isotope tracers, were studied in soil bioretention mesocolumns (8 unique plant species). Total denitrification gene reads per million (rpm) were positively correlated with % denitrified ( r = 0.69) but negatively correlated with total NOx removal following simulated rain events ( r = -0.79). This is likely due to plant-microbe interactions. Plant species with greater root volume, plant and microbial assimilation %, and NOx removal % had lower denitrification genes and rates. This implies that although microorganisms have access to N, advantageous functions, like denitrification, may not increase. At the conclusion of the 1.5-year experiment, the microbial community was strongly influenced by plant species within the Top zone dominated by plant roots, and the presence or absence of a saturated zone influenced the microbial community within the Bottom zone. Leptospermum continentale was an outlier from the other plants and had much lower denitrification gene rpm (average 228) compared to the other species (range: 277 to 413). The antimicrobial properties and large root volume of Leptospermum continentale likely caused this denitrification gene depression.
Biogeochemical Controls on the Relative Importance of Denitrification and Dissimilatory Nitrate Reduction to Ammonium in Estuaries
Publisher: American Geophysical Union (AGU)
Date: 07-2018
DOI: 10.1029/2018GB005908
Pore‐water exchange driven by tidal pumping causes alkalinity export in two intertidal inlets
Publisher: Wiley
Date: 30-08-2014
Factoring stream turbulence into global assessments of nitrogen pollution
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-03-2018
Abstract: A combination of physical transport processes and biologically mediated reactions in streams and their sediments removes dissolved inorganic nitrogen (DIN) from the water. Although stream chemistry and biology have been considered the dominant controls on how quickly DIN is removed, Grant et al. show that physics is what sets the limits on removal rates of nitrate (a component of DIN). Residence time in the hyporheic zone (the region below the sediment surface where groundwater and surface water mix) determines the maximum rate at which nitrate can be removed from stream water. Nevertheless, at local scales, chemistry and biology modify how closely to that maximum rate removal occurs. Science , this issue p. 1266
Underway determination of dissolved inorganic carbon in estuarine waters by gas-diffusion flow analysis with C 4D detection
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2AY25113B
Supplementary material to "The importance of nitrogen fixation to a temperate, intertidal embayment determined using a stable isotope mass balance approach"
Publisher: Copernicus GmbH
Date: 27-11-2017
Root effects on the spatial and temporal dynamics of oxygen in sand-based laboratory-scale constructed biofilters
Publisher: Elsevier BV
Date: 09-2013
Which species? A decision-support tool to guide plant selection in stormwater biofilters
Publisher: Elsevier BV
Date: 03-2018
Bacterial fermentation and respiration processes are uncoupled in anoxic permeable sediments
Publisher: Springer Science and Business Media LLC
Date: 11-03-2019
DOI: 10.1038/S41564-019-0391-Z
Abstract: Permeable (sandy) sediments cover half of the continental margin and are major regulators of oceanic carbon cycling. The microbial communities within these highly dynamic sediments frequently shift between oxic and anoxic states, and hence are less stratified than those in cohesive (muddy) sediments. A major question is, therefore, how these communities maintain metabolism during oxic-anoxic transitions. Here, we show that molecular hydrogen (H
Efficient long-range conduction in cable bacteria through nickel protein wires
Publisher: Springer Science and Business Media LLC
Date: 28-06-2021
DOI: 10.1038/S41467-021-24312-4
Abstract: Filamentous cable bacteria display long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on in idual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating protein shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.
Influence of buried Ulva lactuca on denitrification in permeable sediments
Publisher: Inter-Research Science Center
Date: 17-02-2014
DOI: 10.3354/MEPS10611
Dissimilatory nitrate reduction to ammonium coupled to Fe(II) oxidation in sediments of a periodically hypoxic estuary
Publisher: Wiley
Date: 28-10-2015
DOI: 10.1002/LNO.10220
Constraining denitrification in permeable wave-influenced marine sediment using linked hydrodynamic and biogeochemical modeling
Publisher: Elsevier BV
Date: 10-2008
Processes and drivers of nitrogen removal in stormwater biofiltration
Publisher: Informa UK Limited
Date: 06-03-2014
Nitrogen stable isotope values of large-bodied consumers reflect urbanization of coastal catchments
Publisher: Inter-Research Science Center
Date: 19-01-2016
DOI: 10.3354/MEPS11543
The isotope effect of denitrification in permeable sediments
Publisher: Elsevier BV
Date: 05-2014
Assimilation of Diazotrophic Nitrogen into Pelagic Food Webs
Publisher: Public Library of Science (PLoS)
Date: 28-06-2013
Negligible isotopic fractionation of nitrogen within temperate <i>Zostera</i> spp. meadows
Publisher: Copernicus GmbH
Date: 04-12-2018
Abstract: Abstract. Seagrass meadows form an ecologically important ecosystem in the coastal zone. The 15N∕14N ratio of seagrass is commonly used to assess the extent to which sewage-derived nitrogen may be influencing seagrass beds. There have, however, been few studies comparing the 15N∕14N ratios of seagrass beds, their associated sediments and, of critical importance, the porewater NH4+ pool, which is most bioavailable. Here, we undertook a study of the 15N∕14N ratios of seagrass tissue, sediment porewater NH4+ pool and the bulk sediment to elucidate the extent of any fractionating processes taking place during organic matter mineralisation and nitrogen assimilation. The study was undertaken within two coastal embayments known to receive nitrogen from a range of sources including marine, urban and sewage sources. There was close agreement between the bulk sediment δ15N and seagrass δ15N (r2 of 0.92 and mean offset of 0.9 ‰), illustrating a close coupling between the plant and sediment pools. The δ15N of porewater NH4+ was strongly correlated with the δ15N of both the sediment and the seagrass tissue. For both of these relationships, however, the intercept of the line was not significantly different from 0 and the slopes were not 1:1, reflecting an enrichment of the porewater NH4+ δ15N pool relative to seagrass tissue and bulk sediment δ15N at high δ15N values. We suggest that nitrogen fixation is the most likely explanation for the observation that the δ15N of seagrass tissue is lower than porewater NH4+. Conversely, we suggest that the most likely explanation for the enrichment of porewater NH4+ above bulk sediment was through the preferential mineralisation of isotopically enriched algal material (nitrogen derived from sewage sources) within the sediment as δ15N increased in the vicinity of a sewage treatment plant.
Quantitative determination of polyphosphate in sediments using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy and partial least squares regression
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2AN35289C
Abstract: Phosphorus (P) is a major cause of eutrophication and subsequent loss of water quality in freshwater ecosystems. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. Despite the broad relevance of polyphosphate (Poly-P) in bioremediation and P release processes in the environment, its quantification is not yet well developed for sediment s les. Current methods possess significant disadvantages because of the difficulties associated with using a single extractant to extract a specific P compound without altering others. A fast and reliable method to estimate the quantitative contribution of microorganisms to sediment P release processes is needed, especially when an excessive P accumulation in the form of polyphosphate (Poly-P) occurs. Development of novel approaches for application of emerging spectroscopic techniques to complex environmental matrices such as sediments significantly contributes to the speciation models of P mobilization, biogeochemical nutrient cycling and development of nutrient models. In this study, for the first time Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy in combination with partial least squares (PLS) was used to quantify Poly-P in sediments. To reduce the high absorption matrix components in sediments such as silica, a physical extraction method was developed to separate sediment biological materials from abiotic particles. The aim was to achieve optimal separation of the biological materials from sediment abiotic particles with minimum chemical change in the s le matrix prior to ATR-FTIR analysis. Using a calibration set of 60 s les for the PLS prediction models in the Poly-P concentration range of 0-1 mg g(-1) d.w. (dry weight of sediment) (R(2) = 0.984 and root mean square error of prediction RMSEP = 0.041 at Factor-1) Poly-P could be detected at less than 50 μg g(-l) d.w. Using this technique, there is no solvent extraction or chemical treatment required, s le preparation is minimal and simple, and the analysis time is greatly reduced. The results from this study demonstrated the potential of ATR FT-IR spectroscopy as an alternative method to study Poly-P in sediments.
Interactions between design, plant growth and the treatment performance of stormwater biofilters
Publisher: Elsevier BV
Date: 08-2017
Effects of organic perturbation on marine sediment betaproteobacterial ammonia oxidizers and on benthic nitrogen biogeochemistry
Publisher: Inter-Research Science Center
Date: 19-10-2009
DOI: 10.3354/MEPS08244
Hypoxic events stimulate nitrogen recycling in a shallow salt-wedge estuary: The Yarra River estuary, Australia
Publisher: Wiley
Date: 21-08-2012
Bacterial community shifts in organically perturbed sediments
Publisher: Wiley
Date: 29-09-2007
DOI: 10.1111/J.1462-2920.2006.01110.X
Abstract: Bacterial abundance, ersity and sediment function were investigated in organically perturbed sediments under Tasmanian salmon (Salmo salar) farms and adjacent reference sites. Bacterial numbers increased as farming and organic loading progressed through the farm stocking cycle and declined during the fallow period, although not to prestocking levels. Bacterial numbers ranged between approximately 2 x 10(8) and 3 x 10(9) cells per gram of sediment and were higher at cage sites than reference sites. Microelectrode and respiration data also demonstrated a clear effect of organic loading on sediments. Denaturing gradient gel electrophoresis (DGGE) showed that bacterial communities shifted both in response to farm loading and its cessation. A seasonal effect on microbial communities was also evident. Although bacterial communities did shift again during the fallowing period, this shift was not necessarily a return to preloading communities. The complexity of community shifts may be affected by the vast functional redundancy of bacterial groups. All bacterial communities, including those at reference sites, were highly dynamic. Respiration studies of amended sediments indicated that fish farm sediments were at least as resilient and erse as reference site communities. The results of this study indicate that the functional redundancy of highly complex bacterial communities contributes to their robustness. The relationship between ersity and stability in bacterial communities remains unclear and requires further investigation before an understanding of bacterial response to perturbation is possible.
Pulses of labile carbon cause transient decoupling of fermentation and respiration in permeable sediments
Publisher: Wiley
Date: 31-07-2023
DOI: 10.1002/LNO.12411
Abstract: Dihydrogen (H 2 ) is an important intermediate in anaerobic microbial processes, and concentrations are tightly controlled by thermodynamic limits of consumption and production. However, recent studies reported unusual H 2 accumulation in permeable marine sediments under anoxic conditions, suggesting decoupling of fermentation and sulfate reduction, the dominant respiratory process in anoxic permeable marine sediments. Yet, the extent, prevalence and potential triggers for such H 2 accumulation and decoupling remain unknown. We surveyed H 2 concentrations in situ at different settings of permeable sand and found that H 2 accumulation was only observed during a coral spawning event on the Great Barrier Reef. A flume experiment with organic matter addition to the water column showed a rapid accumulation of hydrogen within the sediment. Laboratory experiments were used to explore the effect of oxygen exposure, physical disturbance and organic matter inputs on H 2 accumulation. Oxygen exposure had little effect on H 2 accumulation in permeable sediments suggesting both fermenters and sulfate reducers survive and rapidly resume activity after exposure to oxygen. Mild physical disturbance mimicking sediment resuspension had little effect on H 2 accumulation however, vigorous shaking led to a transient accumulation of H 2 and release of dissolved organic carbon suggesting mechanical disturbance and cell destruction led to organic matter release and transient decoupling of fermenters and sulfate reducers. In summary, the highly dynamic nature of permeable sediments and its microbial community allows for rapid but transient decoupling of fermentation and respiration after a C pulse, leading to high H 2 levels in the sediment.
The balance between nitrogen fixation and denitrification on vegetated and non‐vegetated intertidal sediments
Publisher: Wiley
Date: 18-07-2016
DOI: 10.1002/LNO.10353
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
Quantifying denitrification in rippled permeable sands through combined flume experiments and modeling
Publisher: Wiley
Date: 07-2012
Does denitrification occur within porous carbonate sand grains?
Publisher: Copernicus GmbH
Date: 23-12-2016
DOI: 10.5194/BG-2016-530
Abstract: Abstract. Carbonate sands form a major sediment type in coral reef environments and play a major role in organic matter recycling. It has previously been postulated that porosity of carbonate sand grains may lead to the formation of anoxic microniches that promote denitrification within these sediments. Under this conceptual model, we expect diffusion to exert an influence on process rates, which can be tested by determining their dependence to reactant concentrations. Here, we use two experiments in flow-through reactors to test this hypothesis in carbonate sediments collected from Heron Island, Australia. Denitrification was only observed to commence at substantial rates below 10 μM O2, suggesting anoxic microniches do not exist. Furthermore, denitrification rates were constant above 18 μM nitrate, suggesting no diffusion limitation, as would be expected if significant rates of reaction were occurring within porous grains. Potential rates of denitrification rates relative to respiration were broadly consistent with those previously reported in silicate sands.
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