ORCID Profile
0000-0001-9891-0560
Current Organisation
University of South Australia
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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)
Analytical Chemistry | Ecology | Microbiology Not Elsewhere Classified | Sensor (Chemical And Bio-) Technology | Environmental Chemistry (Incl. Atmospheric Chemistry) | Electroanalytical Chemistry | Marine And Estuarine Ecology (Incl. Marine Ichthyology) | Natural Resource Management |
ANZSRC Socio-Economic Objective (SEO)
Exploration | Physical and chemical conditions | Water services and utilities | Waste management | Fish | Waste management and recycling
Related Links
Publications
Benthic metabolism and nitrogen dynamics in an urbanised tidal creek: Domination of DNRA over denitrification as a nitrate reduction pathway
Publisher: Elsevier BV
Date: 10-2013
Evaluation of DGT techniques for measuring inorganic uranium species in natural waters: Interferences, deployment time and speciation
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.ACA.2012.06.011
Abstract: Three adsorbents (Chelex-100, manganese dioxide [MnO(2)] and Metsorb), used as binding layers with the diffusive gradient in thin film (DGT) technique, were evaluated for the measurement of inorganic uranium species in synthetic and natural waters. Uranium (U) was found to be quantitatively accumulated in solution (10-100μgL(-1)) by all three adsorbents (uptake efficiencies of 80-99%) with elution efficiencies of 80% (Chelex-100), 84% (MnO(2)) and 83% (Metsorb). Consistent uptake occurred over pH (5-9), with only MnO(2) affected by pH<5, and ionic strength (0.001-1molL(-1) NaNO(3)) ranges typical of natural waters, including seawater. DGT validation experiments (5 days) gave linear mass uptake over time (R(2)≥0.97) for all three adsorbents in low ionic strength solution (0.01M NaNO(3)). Validation experiments in artificial sea water gave linear mass uptake for Metsorb (R(2)≥0.9954) up to 12h and MnO(2) (R(2)≥0.9259) up to 24h. Chelex-100 demonstrated no linear mass uptake in artificial sea water after 8h. Possible interferences were investigated with SO(4)(2-) (0.02-200mgL(-1)) having little affect on any of the three DGT binding layers. PO(4)(3-) additions (5μgL(-1)-5mgL(-1)) interfered by forming anionic uranyl phosphate complexes that Chelex-100 was unable to accumulate, or by directly competing with the uranyl species for binding sites, as with MnO(2) and the Metsorb. HCO(3)(-) (0.1-500mgL(-1)) additions formed anionic species which interfered with the performance of the Chelex-100 and the MnO(2), and the Ca(2+) (0.1-500mgL(-1)) had the affect of forming labile calcium uranyl species which aided uptake of U by all three resins. DGT field deployments in sea water (South ton Water, UK) gave a linear mass uptake of U over time with Metsorb and MnO(2) (4 days). Field deployments in fresh water (River Lambourn, UK) gave linear uptake for up to 7 and 4 days for Metsorb and MnO(2) respectively. Field deployment of the Metsorb-DGT s lers with various diffusive layer thicknesses (0.015-0.175cm) allowed accurate measurements of the diffusive boundary layer (DBL) and allowed DBL corrected concentrations to be determined. This DBL-corrected U concentration was half that determined when the effect of the DBL was not considered. The ability of the DGT devices to measure U isotopic ratios with no isotopic fractionation was shown by all three resins, thereby proving the usefulness of the technique for environmental monitoring purposes.
Evaluation of the diffusive gradient in a thin film technique for monitoring trace metal concentrations in estuarine waters
Publisher: American Chemical Society (ACS)
Date: 10-05-2003
DOI: 10.1021/ES026425Y
Abstract: Monitoring trace metal concentrations in dynamic estuarine waters is not straightforward. This study demonstrated that important information could be obtained from intensive s ling of physicochemical parameters and trace metal concentrations, in the Gold Coast Broadwater, Australia. A regular pattern of variation in Cu and Ni concentrations was related to the movement of water passed point sources with tidal flows, rather than due to conventional estuarine mixing of end-member waters. However, this approach was logistically demanding and expensive. The diffusive gradients in a thin film (DGT) technique was used as an alternative method due to its continual time-integrated response to changes in trace metal concentrations. Significant correlations were found between 24 h DGT-labile measurements and 0.45-microm filterable measurements, on time-averaged composite s les (grab s les combined every 4 h for 24 h), for Cu (n = 24, r = 0.965, p < 0.001), Pb (n = 24, r = 0.799, p < 0.001), Zn (n = 17, r = 0.909, p < 0.001), and Ni (n = 23, r = 0.916, p < 0.001). DGT-labile measurements as a fraction of 0.45 microm-filterable concentrations were 21 +/- 2% for Cu, 29 +/- 11% for Pb, 28 +/- 5% for Zn, and 27 +/- 12% for Ni, demonstrating the speciation capabilities of DGT. Although DGT measurements were confirmed as being highly operationally defined, DGT was still found to be very promising as a monitoring approach, particularly for dynamic estuarine waters.
Representative measurement of two-dimensional reactive phosphate distributions and co-distributed iron(II) and sulfide in seagrass sediment porewaters
Publisher: Elsevier BV
Date: 11-2011
DOI: 10.1016/J.CHEMOSPHERE.2011.07.020
Abstract: The high degree of heterogeneity within sediments can make interpreting one-dimensional measurements difficult. The recent development and use of in situ techniques that measure two-dimensional distributions of porewater solutes have facilitated investigation of the role of spatial heterogeneity in sediment biogeochemistry. A colourimetric diffusive equilibration in thin films method has been developed that allows two-dimensional, high-resolution measurement of reactive phosphate in sediment porewaters. A method detection limit of 0.22 μM, an effective upper limit of ~1000 μM and relative standard deviations typically below 5% were achieved. This method was evaluated by deployment in seagrass (Zostera capricorni) colonised sediments, as part of combined probes with similar colourimetric methods for sulfide and iron(II). The two-dimensional, high resolution distributions obtained provide a highly representative measurement of the co-distributions of porewater solutes, allowing heterogeneous features and biogeochemical processes to be observed and interpreted. Microniches of high phosphate concentration >100 μM were observed throughout the distributions and were interpreted to be due to localised zones of rapid organic matter mineralisation, possibly using electron acceptors other than iron(III) oxyhydroxides (e.g. aerobic respiration) as often they did not correspond with microniches of higher Fe(II) concentration.
Influence of Trypaea australiensis population density on benthic metabolism and nitrogen dynamics in sandy estuarine sediment: A mesocosm simulation
Publisher: Elsevier BV
Date: 02-2009
A modified DGT technique for the simultaneous measurement of dissolved inorganic nitrogen and phosphorus in freshwaters
Publisher: Elsevier BV
Date: 10-2017
DOI: 10.1016/J.ACA.2017.08.024
Abstract: A modified diffusive gradients in thin films (DGT) technique uses both a mixed binding layer (PrCH and A520E resins for NH
Titanium dioxide-based DGT technique for in situ measurement of dissolved reactive phosphorus in fresh and marine waters
Publisher: American Chemical Society (ACS)
Date: 23-11-2010
DOI: 10.1021/ES1027713
Abstract: A new diffusive gradients in a thin film (DGT) technique for measuring dissolved reactive phosphorus (DRP) in fresh and marine waters is reported. The new method, which uses a commercially available titanium dioxide based adsorbent (Metsorb), was evaluated and compared to the well-established ferrihydrite-DGT method (ferrihydrite cast within the polyacrylamide gel). DGT time-series experiments showed that the mass of DRP accumulated by Metsorb and ferrihydrite was linear with time when deployed in simple solutions. Both DGT methods showed predictable uptake across the pH (4.0-8.3) and ionic strength (0.0001-1 mol L(-1) NaNO(3)) ranges investigated, and the total capacity of the Metsorb binding phase (∼40,000 ng P) was 2.5-5 times higher than the reported total capacity of the ferrihydrite binding phase. The measurement of DRP in synthetic freshwater and synthetic seawater by Metsorb-DGT over a 4 day deployment period showed excellent agreement with the concentration of DRP measured directly in solution, whereas the ferrihydrite-DGT method significantly underestimated (23-30%) the DRP concentration in synthetic seawater for deployment times of two days or more. Field deployments of Metsorb-DGT s lers with various diffusive layer thicknesses allowed accurate measurement of both the diffusive boundary layer thickness and DRP concentration in situ. The Metsorb-DGT method performs similarly to ferrihydrite-DGT for freshwater measurements but is shown to be more accurate than the ferrihydrite method for determining DRP in seawater.
Effects of the bioturbating marine yabby Trypaea australiensis on sediment properties in sandy sediments receiving mangrove leaf litter
Publisher: MDPI AG
Date: 25-11-2019
DOI: 10.3390/JMSE7120426
Abstract: Laboratory mesocosm incubations were undertaken to investigate the influence of burrowing shrimp Trypaea australiensis (marine yabby) on sediment reworking, physical and chemical sediment characteristics and nutrients in sandy sediments receiving mangrove (Avicennia marina) leaf litter. Mesocosms of sieved, natural T. australiensis inhabited sands, were continually flushed with fresh seawater and pre-incubated for 17 days prior to triplicates being assigned to one of four treatments sandy sediment (S), sediment + yabbies (S+Y), sediment + leaf litter (organic matter S+OM) and sediment + yabbies + leaf litter (S+Y+OM) and maintained for 55 days. Mangrove leaf litter was added daily to treatments S+OM and S+Y+OM. Luminophores were added to mesocosms to quantify sediment reworking. Sediment s les were collected after the pre-incubation period from a set of triplicate mesocosms to establish initial conditions prior to the imposition of the treatments and from the treatment mesocosms at the conclusion of the 55-day incubation period. Yabbies demonstrated a clear effect on sediment topography and leaf litter burial through burrow creation and maintenance, creating mounds on the sediment surface ranging in diameter from 3.4 to 12 cm. Within S+Y+OM sediments leaf litter was consistently removed from the surface to sub-surface layers with only 7.5% ± 3.6% of the total mass of leaf detritus added to the mesocosms remaining at the surface at the end of the 55-day incubation period. Yabbies significantly decreased sediment wet-bulk density and increased porosity. Additionally, T. australiensis significantly reduced sediment bio-available ammonium (NH4+bio) concentrations and altered the shape of the concentration depth profile in comparison to the non-bioturbated mesocosms, indicating influences on nutrient cycling and sediment-water fluxes. No significant changes for mean apparent biodiffusion coefficients (Db) and mean biotransport coefficients (r), were found between the bioturbated S+Y and S+Y+OM mesocosms. The findings of this study provide further evidence that T. australiensis is a key-species in shallow intertidal systems playing an important role as an ‘ecosystem engineer’ in soft-bottom habitats by significantly altering physical and chemical structures and biogeochemical function.
Simultaneous measurement of trace metal and oxyanion concentrations in water using diffusive gradients in thin films with a chelex-metsorb mixed binding layer
Publisher: American Chemical Society (ACS)
Date: 04-12-2014
DOI: 10.1021/AC402247J
Abstract: A new diffusive gradients in thin films (DGT) technique with a mixed binding layer (Chelex-100 and the titanium dioxide based adsorbent Metsorb) is described for the simultaneous measurement of labile trace metal (Mn, Co, Ni, Cu, Cd, and Pb) and oxyanion (V, As, Mo, Sb, W, and P) concentrations in freshwater and seawater. The mixed binding layer (MBL) DGT technique was evaluated against the Chelex-DGT and Metsorb-DGT techniques, and all elution efficiencies and diffusion coefficients have been remeasured for the above analytes. Diffusion coefficients (D) measured using MBL-DGT generally agreed well with those measured by Chelex-DGT (DMBL/DChelex = 0.97-1.05), Metsorb-DGT (DMBL/DMetsorb = 0.97-1.01), and diffusion cell experiments. The measurement of trace metals and oxyanions by MBL-DGT was independent of pH (5.03-8.05) and ionic strength (I = 0.001-0.7 mol L(-1)). MBL-DGT accurately measured the concentration of trace metals and oxyanions in synthetic freshwater (CMBL/CSol = 0.82-1.18) over the 4 day deployment and also agreed well with Metsorb-DGT (CMBL/CMetsorb = 0.84-0.94) and Chelex-DGT (CMBL/CChelex = 0.88-1.11) measurements. In synthetic seawater, MBL-DGT accurately measured the concentration of metals and oxyanions (CMBL/CSol = 0.85-1.12) over 4 days, with the exception of Mo-none of the DGT techniques were capable of measuring Mo in seawater. MBL-DGT measured the Mn concentration accurately over the entire 4 day period, whereas Chelex-DGT only measured Mn accurately up to 2 days. The MBL-DGT method described in this study offers significant advantages over the ferrihydrite-Chelex-DGT method reported previously. These advantages include the commercial availability of both Metsorb and Chelex-100, the higher accuracy of Metsorb for measuring some oxyanions in freshwater and seawater, and the possibility of measuring Fe, which would not be possible using the Chelex-ferrihydrite binding layer.
Metal speciation measurement by diffusive gradients in thin films technique with different binding phases
Publisher: Elsevier BV
Date: 03-2005
Short-term variability of nutrients and fecal indicator bacteria within the gold coast seaway, southern Moreton Bay (Australia)
Publisher: Coastal Education and Research Foundation
Date: 2012
Influence of natural amphipod (Victoriopisa australiensis) (Chilton, 1923) population densities on benthic metabolism, nutrient fluxes, denitrification and DNRA in sub-tropical estuarine sediment
Publisher: Springer Science and Business Media LLC
Date: 16-03-2009
The development and evaluation of a microstill with conductance detection for low level ammonia monitoring in chloraminated water
Publisher: Elsevier BV
Date: 08-2019
DOI: 10.1016/J.TALANTA.2019.03.043
Abstract: Monitoring low levels of ammonia in chloraminated water can be challenging but is important for effectively managing potable water disinfection. The lower the concentration of free ammonia that can be determined, the tighter the control at the disinfection point, which supports better maintenance of chloramine residuals in the distribution system. In this study a micro-distillation technique was used to selectively separate ammonia into a boric acid solution allowing determination by conductance (i.e., micro-distillation and conductance measurement instrument - Micro-DCMI). The optimised technique had a linear calibration range of 0.01-60 mg NH
Development and evaluation of the diffusive gradients in thin films technique for measuring nitrate in freshwaters
Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/J.ACA.2016.04.006
Abstract: A new diffusive gradients in thin films (DGT) technique, using Purolite A520E anion exchange resin, was developed and evaluated for the measurement of NO3N in freshwaters. Purolite A520E had a very high uptake efficiency (>98%) and elution efficiency (82.7% with 2 mol L(-1) NaCl as eluent) for NO3N. The 24 h mass vs. time validation experiments had excellent linearity (R(2) ≥ 0.997) and the intrinsic capacity of the binding layer for NO3N was 849 ± 24 μg. NO3N uptake was quantitative over a pH (3.5-8.5) range typical of most natural freshwaters. Several anions competed with NO3N to produce a lower effective binding capacity for NO3N in the following order of selectivity, Cl(-) > HCO3(-) > SO4(2-) > H2PO4(-), although NO3N measurements were quantitative at ionic strengths 0.0001-0.008 mol L(-1) as NaCl. NO2N did not adversely affect determination of NO3N at typical concentrations. Field deployments of DGT s lers with varying diffusive layer thicknesses validated the use of the technique in situ, allowed calculation of the diffusive boundary layer and accurate measurement of NO3N (CDGT/CSOLN 1.03-1.04). Reproducibility of the technique during field deployments was good (relative standard deviation < 3.2%). Limits of detection of A520E-DGT for NO3N were 13.15 μg L(-1) and 7.52 μg L(-1) (equivalent to 0.94 and 0.54 μmol L(-1)) based on 24 h and 48 h deployments, respectively. A520E-DGT determined NO3N concentrations during field deployments were very similar to the average values obtained from 0.45 μm filtered grab s les, which confirmed that the new DGT technique produced highly representative results.
Geochemical cycling and speciation of copper in waters and sediments of Macquarie Harbour, Western Tasmania
Publisher: Elsevier BV
Date: 06-2003
Selective determination of Cr(VI) oxyanions using a poly‐3‐methylthiophene‐modified electrode
Publisher: Wiley
Date: 11-1989
Evaluating use of ferricyanide-mediated respiration bioassays to quantify stimulatory and inhibitory effects on Escherichia coli populations
Publisher: Elsevier BV
Date: 15-03-2010
DOI: 10.1016/J.TALANTA.2009.10.057
Abstract: A number of recent studies have utilised ferricyanide as a respiratory mediator for microbial-based assays for determining water quality parameters such as biochemical oxygen demand (BOD) and toxicity. The majority of assays published to date obtain a result by determining the difference in ferrocyanide accumulation between a test s le and one or more control s les. However, a validation of the relationship between ferrocyanide accumulation and standard measures of cell density or viability has not yet been performed. To this end, a rapid microbially catalysed ferricyanide-mediated respiration (FM-RES) assay was compared with standard plate count (SPC) and spectrophotometer (OD(600)) measurements on a growing batch culture of Escherichia coli. Good agreement was observed between all techniques, with predictable deviations noted in different phases of the growth curves. Standardised FM-RES assays showed excellent correlations with the SPC method under controlled conditions, indicating that short-term changes in microbial activity are due to a change in per-cell respiration, rather than changes in cell numbers. The FM-RES assay was then used to observe the changes in the respiration of E. coli induced by the addition of a glucose-glutamic acid (GGA) mixture, 3,5-dichlorophenol (3,5-DCP) and Ag(+) in various combinations and concentrations. Stimulation of respiration was pronounced in the presence of GGA while both 3,5-DCP and, in particular, Ag(+) demonstrated inhibitory respiratory effects. The results highlight the validity and suitability of ferricyanide-mediated respiration bioassays, with appropriate modification, to monitor either stimulatory effects on microbial populations, such as occurs with BOD, or inhibitory effects, such as occurs with toxicity assays.
Investigating the distribution and sources of organic matter in surface sediment of Coombabah Lake (Australia) using elemental, isotopic and fatty acid biomarkers
Publisher: Elsevier BV
Date: 10-2008
DGT measurement of dissolved aluminum species in waters: Comparing chelex-100 and titanium dioxide-based adsorbents
Publisher: American Chemical Society (ACS)
Date: 06-02-2012
DOI: 10.1021/ES203674N
Abstract: Aluminum is acutely toxic, and elevated concentrations of dissolved Al can have detrimental effects on both terrestrial and aquatic ecosystems. Robust analytical methods that can determine environmentally relevant Al fractions accurately and efficiently are required by the environmental monitoring community. A simple, robust passive s ling method, the diffusive gradients in thin films (DGT) technique, was evaluated for the measurement of dissolved Al species in freshwater and marine water using either Chelex-100 or Metsorb (a titanium dioxide-based binding agent) as the adsorbent. Mass vs time DGT deployments at pH 5.05 (Al(3+) and Al(OH)(2+) dominate) and 8.35 (Al(OH)(4)(-) dominates) demonstrated linear uptake of Al (R(2) = 0.989 and 0.988, respectively) for Metsorb. Similar deployments of Chelex-DGT showed linear uptake at pH 5.05 (R(2) = 0.994) however, at pH 8.35 the mass of Al accumulated was 40-70% lower than predicted, suggesting that Chelex-100 is not suitable for Al measurements at high pH. The Metsorb-DGT measurement was independent of pH (5.0-8.5) and ionic strength (0.001-0.7 mol L(-1) NaNO(3)), whereas the Chelex-DGT measurement was only independent of ionic strength at pH 5.0. At pH 8.4, increasing ionic strength led to considerable underestimation (up to 67%) of Al concentration. Deployments of Metsorb-DGT (up to 4 days) in synthetic freshwater (pH range 5.4-8.1) and synthetic seawater (pH 8.15) resulted in linear mass uptakes, and the concentration measured by DGT agreed well with solution concentrations. Conversely, deployment of Chelex-DGT in synthetic seawater and freshwater (pH ≥7.7 Al(OH)(4)(-) dominant species) resulted in a decrease in accumulated mass with increasing deployment time. In situ field evaluations in fresh, estuarine, and marine waters confirmed that Metsorb-DGT was more accurate than Chelex-DGT for the measurement of dissolved Al in typical environmental waters.
Seasonal nutrient cycling in integrated rice-shrimp ponds
Publisher: Elsevier BV
Date: 12-2019
Optimization of colorimetric DET technique for the in situ, two-dimensional measurement of iron(II) distributions in sediment porewaters
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.TALANTA.2011.11.020
Abstract: The recently developed colorimetric diffusive equilibration in thin films (DET) technique for the in situ, high-resolution measurement of iron(II) in marine sediments is optimized to allow measurement of the higher iron concentrations typical of freshwater sediment porewaters. Computer imaging densitometry (CID) is used to analyze the retrieved s lers following exposure to ferrozine, a colorimetric reagent selective for iron(II). The effect of ferrozine concentration, image processing parameters and ionic strength are investigated to improve the applicability of this technique to a wider range of aquatic systems than reported in the first publications of this approach. The technique was optimized to allow detection of up to 2,000 μmol L(-1) iron(II), a four-fold increase on the previous upper detection limit of 500 μ mol L(-1). The CID processing of the scanned color image was also optimized to adjust the sensitivity of the assay as required by processing the image with different color channel filters, the sensitivity of the assay can be optimized for lower concentrations (up to 100 μmol L(-1)) or higher concentrations (up to 2,000 μmol L(-1)) of iron(II), depending on the specific site characteristics. This process does not require separate s ling probes or even separate scans of the DET gels as the color filter and grayscale conversion is done post-image capture. The optimized technique is very simple to use and provides highly representative, high-resolution (1mm) two-dimensional distributions of iron(II) in sediment porewaters. The detection limit of the optimized technique was 4.1±0.3 μmol L(-1) iron(II) and relative standard deviations were less than 6%.
Removing ammonium from water and wastewater using cost-effective adsorbents: A review
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.JES.2017.09.009
Abstract: Ammonium is an important nutrient in primary production however, high ammonium loads can cause eutrophication of natural waterways, contributing to undesirable changes in water quality and ecosystem structure. While ammonium pollution comes from diffuse agricultural sources, making control difficult, industrial or municipal point sources such as wastewater treatment plants also contribute significantly to overall ammonium pollution. These latter sources can be targeted more readily to control ammonium release into water systems. To assist policy makers and researchers in understanding the ersity of treatment options and the best option for their circumstance, this paper produces a comprehensive review of existing treatment options for ammonium removal with a particular focus on those technologies which offer the highest rates of removal and cost-effectiveness. Ion exchange and adsorption material methods are simple to apply, cost-effective, environmentally friendly technologies which are quite efficient at removing ammonium from treated water. The review presents a list of adsorbents from the literature, their adsorption capacities and other parameters needed for ammonium removal. Further, the preparation of adsorbents with high ammonium removal capacities and new adsorbents is discussed in the context of their relative cost, removal efficiencies, and limitations. Efficient, cost-effective, and environmental friendly adsorbents for the removal of ammonium on a large scale for commercial or water treatment plants are provided. In addition, future perspectives on removing ammonium using adsorbents are presented.
Short-term nitrogen and phosphorus release during the disturbance of surface sediments: A case study in an urbanised estuarine system (Gold Coast Broadwater, Australia)
Publisher: MDPI AG
Date: 07-04-2017
DOI: 10.3390/JMSE5020016
The effect of manipulating sediment pH on the porewater chemistry of copper- and zinc-spiked sediments
Publisher: Elsevier BV
Date: 10-2007
A sensitive, rapid ferricyanide-mediated toxicity bioassay developed using Escherichia coli
Publisher: Elsevier BV
Date: 15-07-2010
DOI: 10.1016/J.TALANTA.2010.05.046
Abstract: A need for rapid toxicity techniques has seen recent research into developing new microbiological assays and characterising their toxicity responses using a range of substances. A microbiological bioassay that determines changes in ferricyanide-mediated respiration for toxicity measurement (FM-TOX) shows particular promise. The development and optimisation of an improved FM-TOX method, incorporating novel features, is described using Escherichia coli as the biocatalyst. Omission of an exogenous carbon source, used in previously described FM-TOX assays, substantially improves the assay sensitivity. In addition, the development of a two-step procedure (toxicant exposure followed by determination of microbial respiratory activity) was found to enhance the inhibition of E. coli by 3,5-dichlorophenol and four other toxicants, compared to single-step procedures. Other assay parameters, such as the ferricyanide concentration, exposure times and optical density of the biocatalyst were also optimised, sometimes based on practical aspects. Toxicity tests were carried out using the adopted technique on both organic and inorganic toxicants, with classic sigmoid-shaped dose-response curves observed, as well as some non-standard responses. IC(50) data is presented for a number of common toxicants. The optimised assay provides a good foundation for further toxicity testing using E. coli, as well as the potential for expanding the technique to utilise other bacteria with complementary toxicity responses, thereby allowing use of the assay in a range of applications.
A colorimetric DET technique for the high-resolution measurement of two-dimensional alkalinity distributions in sediment porewaters
Publisher: Elsevier BV
Date: 2015
DOI: 10.1016/J.CHEMOSPHERE.2014.07.042
Abstract: Measurements of porewater alkalinity are fundamental to the study of organic matter mineralization in sediments, which plays an essential role in the global cycles of carbon and nutrients. A new colorimetric diffusive equilibration in thin film (DET) technique is described for measuring two-dimensional total alkalinity distributions in sediment porewaters at high resolution (1-2 mm(2)). Thin polyacrylamide hydrogel layers (0.8 mm) equilibrate with the porewater and, after removal, are immediately laid onto another hydrogel containing formic acid, which reacts with alkalinity-generating species, and the pH-indicator bromophenol blue. The resultant color change is quantified using computer-imaging densitometry. The lower limit of detection is 0.2 meq L(-1) and the upper measurement limit is 8 meq L(-1). Deployment in seagrass colonized sediment revealed high levels of spatial heterogeneity in the porewater alkalinity distribution, with concentrations ranging from 2.28 meq L(-1) in the overlying water to 5.13 meq L(-1) in some parts of the sediment. This is the first time that two-dimensional, high-resolution distributions of porewater alkalinity have been measured.
Trace metal speciation measurements in waters by the liquid binding phase DGT device
Publisher: Elsevier BV
Date: 15-09-2005
DOI: 10.1016/J.TALANTA.2005.03.018
Abstract: The speciation measurements of trace metals by the diffusive gradients in thin-films technique (DGT) using a poly(4-styrenesulfonate) (PSS) aqueous solution as a binding phase and a cellulose dialysis membrane (CDM) as a diffusive layer, CDM-PSS DGT, were investigated and showed good agreement with computer modelling calculations. The diffusion coefficients of ethylenediaminetetraacetic acid (EDTA) complexes with Cd(2+) and Cu(2+) were measured and compared with those of the inorganic metal ions. CDM-PSS DGT device was tested for speciation measurement in s le solutions containing EDTA, tannic acid (TA), glucose (GL), dodecylbenzenesulfonic acid (DBS) and humic acid (HA) as complexing ligands forming organic complexes with varying stability constants. Lower percentages of DGT labile copper concentrations over total filterable copper concentrations obtained from the deployments in freshwater sites indicated that copper complexes with organic matter were basically not measured by the devices.
New diffusive gradients in a thin film technique for measuring inorganic arsenic and selenium(IV) using a titanium dioxide based adsorbent
Publisher: American Chemical Society (ACS)
Date: 09-08-2010
DOI: 10.1021/AC101543P
Abstract: A new diffusive gradients in a thin film (DGT) technique, using a titanium dioxide based adsorbent (Metsorb), has been developed and evaluated for the determination of dissolved inorganic arsenic and selenium. As(III), As(V), and Se(IV) were found to be quantitatively accumulated by the adsorbent (uptake efficiencies of 96.5-100%) and eluted in 1 M NaOH (elution efficiencies of 81.2%, 75.2%, and 88.7%). Se(VI) was not quantitatively accumulated by the adsorbent ( or= 0.998) for As(III), As(V), and Se(IV). Consistent uptake occurred over pH (3.5-8.5) and ionic strength (0.0001-0.75 mol L(-1) NaNO(3)) ranges typical of natural waters, including seawater. Field deployments of DGT probes with various diffusive layer thicknesses confirmed the use of the technique in situ, allowing calculation of the diffusive boundary layers and an accurate measurement of inorganic arsenic. Reproducibility of the technique in field deployments was good (relative standard deviation <8%). Limits of detection (4 day deployments) were 0.01 microg L(-1) for inorganic arsenic and 0.05 microg L(-1) for Se(IV). The results of this study confirmed that DGT with Metsorb was a reliable and robust method for the measurement of inorganic arsenic and the selective measurement of Se(IV) within useful limits of accuracy.
In situ speciation of dissolved inorganic antimony in surface waters and sediment porewaters: Development of a thiol-based diffusive gradients in thin films technique for SbIII
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6EM00189K
Abstract: A new in situ s ling method enables the selective measurement of Sb( iii ) in surface waters and sediment porewaters.
Benthic metabolism and nitrogen dynamics in a sub-tropical coastal lagoon: Microphytobenthos stimulate nitrification and nitrate reduction through photosynthetic oxygen evolution
Publisher: Elsevier BV
Date: 11-2012
Contaminants in water, sediment and fish biomonitor species from natural and artificial estuarine habitats along the urbanized Gold Coast, Queensland
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C1EM10664C
Abstract: Metal and pesticide contaminants were measured in water, sediment and fish species in various Gold Coast waterways, Queensland. With the exception of Cu, metal concentrations in water, measured using the diffuse gradients in a thin film (DGT) technique, complied with relevant Australian guidelines. Cu concentrations in these waterways have been related to recreational vessel activities previously. All sediment metal concentrations measured were below the national guidelines, although Cu, Zn and Pb were found to vary significantly between habitat types. Evidence of spikes in sediment pesticide concentrations (some banned over 50 years ago) was observed in some artificial residential waterways. Heavy metals and pesticides were measured in the tissue (muscle, gills and liver) of three economically important species of fish, with different feeding strategies (partly herbivore Arrh hus sclerolepis, carnivore Acanthopagrus australis, detritivore Mugil cephalus). We tested the hypothesis that fish accumulate different amounts of contaminants from wetland habitats affected by different intensities of anthropogenic activities (i.e., marinas, artificial residential canals, artificial residential lakes, estuaries and natural, vegetated waterways). Significantly higher concentrations of Cu were found in the gills of each fish species from marinas compared to fish caught in other waterways. Furthermore, fish caught in canals had the second highest Cu and natural waterways the lowest. These results support the stated hypothesis for Cu and furthermore indicate that these fish species are suitable as biomonitors in estuarine waterways. Metal and pesticide concentrations in the edible muscle tissue of all fish complied with the Australian Food Standard Code recommended limits for human consumption, apart from As which is likely to be due to bioconcentration of lower toxicity organo-As species. These results indicate a low health risk for humans consuming fish, in terms of contaminant levels. The accumulated body of evidence on contaminants within Gold Coast waterways generally suggests that there are no major threats of metal or pesticide contamination, except for marina facilities which are a major source of Cu which also accumulates in fish. Water quality threats are also highlighted in residential canals, presumably as a consequence of their hydrological design.
Characterizing microbial communities and processes in a modern stromatolite (Shark Bay) using lipid biomarkers and two-dimensional distributions of porewater solutes
Publisher: Wiley
Date: 18-02-2014
Abstract: Modern microbial mats are highly complex and dynamic ecosystems. Diffusive equilibration in thin films (DET) and diffusive gradients in thin films (DGT) s lers were deployed in a modern smooth microbial mat from Shark Bay in order to observe, for the first time, two-dimensional distributions of porewater solutes during day and night time. Two-dimensional sulfide and alkalinity distributions revealed a strong spatial heterogeneity and a minor contribution of sulfide to alkalinity. Phosphate distributions were also very heterogeneous, while iron(II) distributions were quite similar during day and night with a few hotspots of mobilization. Lipid biomarkers from the three successive layers of the mat were also analysed in order to characterize the microbial communities regulating analyte distributions. The major hydrocarbon products detected in all layers included n-alkanes and isoprenoids, whilst other important biomarkers included hopanoids. Phospholipid fatty acid profiles revealed a decrease in cyanobacterial markers with depth, whereas sulfate-reducing bacteria markers increased in abundance in accordance with rising sulfide concentrations with depth. Despite the general depth trends in community structure and physiochemical conditions within the mat, two-dimensional solute distributions showed considerable small-scale lateral variability, indicating that the distributions and activities of the microbial communities regulating these solute distributions were equally heterogeneous and complex.
Modelling copper uptake by Saccostrea glomerata with diffusive gradients in a thin film measurements
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/EN07092
Abstract: Environmental context. Organisms, like commercially available rock oysters, can be used to measure the uptake of contaminants (e.g. trace metals) and thereby provide a relative measure of water quality between sites or of water quality changes over time. However, these measurements cannot be directly compared with water quality guidelines, which require water concentrations and not tissue concentrations, to provide an absolute indication of water quality. The present study found that the amount of copper accumulated in oyster tissue was proportional to water copper concentrations measured by passive s ler devices, thereby allowing oyster copper accumulation to be interpreted in terms of biologically-available copper water concentrations and to be compared with the water quality guidelines. Abstract. Copper bioaccumulation in transplanted oysters, Saccostrea glomerata, was compared with measurements of water concentrations. Tissue copper measurements were positively correlated with acid-soluble copper concentrations (n = 6, r = 0.874, P = 0.023) and with DGT (diffusive gradients in a thin film)-accumulated copper mass at two sites (n = 9, r = 0.967, P 0.001 n = 9, r = 0.888, P = 0.001) where continual bioaccumulation occurred. The more significant correlations are likely due to the time-integrated nature of DGT measurements, despite the biomonitor measuring different copper species. This empirical relationship allowed S. glomerata-available copper concentrations (0.70–1.6 μg L–1) to be modelled across 14 sites and produced a highly significant correlation (r = 0.787, P = 0.001) with DGT-labile copper measurements (0.10–0.49 μg L–1). This approach allowed biomonitor measurements to be compared with water quality guidelines and would further expand the use of biomonitors for aquatic monitoring if widely replicated.
Synthesis and characterisation of a polyacrylamide-polyacrylic acid copolymer hydrogel for environmental analysis of Cu and Cd
Publisher: Elsevier BV
Date: 07-2002
Erratum: Macroinfauna dynamics and sediment parameters of a subtropical estuarine lake-Coombabah Lake (Southern Moreton Bay, Australia) (Journal of Coastal Research (2013) 29:6A (156-167))
Publisher: Coastal Education and Research Foundation
Date: 2014
Evaluation of a titanium dioxide-based DGT technique for measuring inorganic uranium species in fresh and marine waters
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.TALANTA.2012.05.012
Abstract: A new diffusive gradients in a thin film (DGT) technique for measuring dissolved uranium (U) in freshwater is reported. The new method utilises a previously described binding phase, Metsorb (a titanium dioxide based adsorbent). This binding phase was evaluated and compared to the well-established Chelex-DGT method. Batch experiments showed quantitative uptake (100±3%) of dissolved U by Metsorb and an elution efficiency of 95% was obtained using a mixed eluent of 1 mol L(-1) NaOH/1 mol L(-1) H(2)O(2). The mass of U accumulated by Metsorb was linear (R(2)≥0.98) with time across the pH range 3.0-8.1, validating the DGT measurement. The measured effective diffusion coefficients were highly dependent on pH, ranging from 2.74-4.81×10(-6)cm(2)s(-1), which were in reasonable agreement with values from the literature. Ionic strength showed no effect on the uptake of U, and thereby on diffusion coefficients, at NaNO(3) concentrations ≤0.01 mol L(-1), but caused the U concentration to be underestimated by 18% and 24% at 0.1 mol L(-1) NaNO(3) and 0.7 mol L(-1) NaNO(3), respectively. Deployment of Metsorb-DGT in synthetic freshwater resulted in reliable measurement of the dissolved U concentration (C(DGT)/C(Sol)=1.05), whereas Chelex-DGT significantly underestimated the dissolved U concentration (C(DGT)/C(Sol)=0.76). Metsorb-DGT was found to give reliable results after 8h deployments in synthetic seawater but experienced competition effects with longer deployments. The Chelex-DGT was unable to measure U at all in synthetic seawater. A field deployment in a freshwater stream (Coomera River) confirmed the utility of the Metsorb-DGT method for measuring U in natural freshwaters, but performance of field deployments may require further evaluation due to the possibility of major changes in uranium speciation with pH and water composition. We recommend a filtered s le, of any water in which DGT measurements are to be made, be used to determine the appropriate diffusion coefficient under controlled laboratory conditions.
Lipid Biomarker and Isotopic Study of Community Distribution and Biomarker Preservation in a Laminated Microbial Mat from Shark Bay, Western Australia
Publisher: Springer Science and Business Media LLC
Date: 27-03-2015
DOI: 10.1007/S00248-015-0598-3
Abstract: Modern microbial mats from Shark Bay present some structural similarities with ancient stromatolites thus, the functionality of microbial communities and processes of diagenetic preservation of modern mats may provide an insight into ancient microbial assemblages and preservation. In this study, the vertical distribution of microbial communities was investigated in a well-laminated smooth mat from Shark Bay. Biolipid and compound-specific isotopic analyses were performed to investigate the distribution of microbial communities in four distinct layers of the mat. Biomarkers indicative of cyanobacteria were more abundant in the uppermost oxic layer. Diatom markers (e.g. C25 HBI alkene, C20:4ω6 and C20:5ω3 polar lipid fatty acids (PLFAs)) were also detected in high abundance in the uppermost layer, but also in the deepest layer under conditions of permanent darkness and anoxia, where they probably used NO3 (-) for respiration. CycC19:0, an abundant PLFA of purple sulfur bacteria (PSB), was detected in all layers and presented the most (13)C-depleted values of all PLFAs, consistent with photoautotrophic PSB. Sulfur-bound aliphatic and aromatic biomarkers were detected in all layers, highlighting the occurrence of early sulfurisation which may be an important mechanism in the sedimentary preservation of functional biolipids in living and, thus, also ancient mats.
Inorganic arsenic and iron(II) distributions in sediment porewaters investigated by a combined DGTcolourimetric DET technique
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/EN11074
Abstract: Environmental contextContamination of aquatic ecosystems with inorganic arsenic is a concern for both environmental and human health. Sediments are an important sink for dissolved arsenic, but they may also act as a source of arsenic because of human-induced changes in aquatic systems. This paper describes a new approach for investigating the status of inorganic arsenic in sediments, based on recent developments in diffusion-based sediment s ling techniques. AbstractA new approach for investigating the biogeochemistry of inorganic arsenic and iron(II) in freshwater, estuarine and marine sediments is reported. The recently developed Metsorb diffusive gradients in thin films (DGT) technique for the measurement of total inorganic arsenic and the colourimetric diffusive equilibration in thin films (DET) technique for the measurement of iron(II), were utilised in combination to determine co-located depth profiles of both solutes in sediment porewaters. DGT-measured porewater arsenic concentrations were typically less than 40 nM, whereas iron(II) concentrations reached up to 704 µM. Statistically significant (P 0.0002) correlations between porewater arsenic and iron(II) profiles were observed (R 0.92) in mesocosms of each sediment type. This approach to investigating arsenic and iron geochemistry in sediments allows the in-situ determination of arsenic and iron species at exactly the same location in the sediment at 3-mm resolution for arsenic and 1-mm resolution for iron(II). The technique was capable of detecting very low concentrations of arsenic, with a detection limit of 0.27 nM (0.02 µg L–1) for a 48-h deployment time. Porewater iron(II), which is often present over a wide range of concentrations, was detectable up to 2000 µM. This study shows the application of these recently developed DGT and DET techniques for the in-situ investigation of inorganic arsenic and iron biogeochemistry in sediments. This approach has the potential to enable simple, yet highly representative assessment of the biogeochemical status of arsenic and iron in a variety of natural sediments, including groundwater sediments where mobilised arsenic is responsible for significant human health risks.
In situ evaluation of DGT techniques for measurement of trace metals in estuarine waters: A comparison of four binding layers with open and restricted diffusive layers
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5EM00550G
Abstract: Four different DGT binding layers were used to make selective measurements of trace metals in coastal waters within The Broadwater (Gold Coast, Queensland).
Ubiquity of activated sludge ferricyanide-mediated BOD methods: A comparison of sludge seeds across wastewater treatment plants
Publisher: Elsevier BV
Date: 07-2014
DOI: 10.1016/J.TALANTA.2014.03.004
Abstract: Many studies have described alternatives to the BOD5 standard method, with substantial decreases in incubation time observed. However, most of these have not maintained the features that make the BOD5 assay so relevant - a high level of substrate bio-oxidation and use of wastewater treatment plant (WWTP) sludge as the biocatalyst. Two recently described ferricyanide-mediated (FM)-BOD assays, one for trade wastes and one for WWTP influents and treated effluents, satisfy these criteria and were investigated further here for their suitability for use with erse biocatalysts. Both FM-BOD assays responded proportionately to increasing substrate concentration with sludges from 11 different WWTPs and temporally (months to years) using sludges from a single WWTP, confirming the broad applicability of both assays. Sludges from four WWTPs were selected as biocatalysts for each FM-BOD assay to compare FM-BOD equivalent values with BOD5 (three different sludge seeds) measurements for 12 real wastewater s les (six per assay). Strong and significant relationships were established for both FM-BOD assays. This study has demonstrated that sludge sourced from many WWTPs may be used as the biocatalyst in either FM-BOD assay, as it is in the BOD5 assay. The industry potential of these findings is substantial given the widespread use of the BOD5 assay, the dramatically decreased incubation period (3-6h) and the superior analytical range of both assays compared to the standard BOD5 assay.
“Diffusive gradients in thin films” techniques provide representative time-weighted average measurements of inorganic nutrients in dynamic freshwater systems
Publisher: American Chemical Society (ACS)
Date: 02-12-2016
Abstract: Nutrient concentrations in freshwater are highly variable over time, with changes driven by weather events, anthropogenic sources, modifications to catchment hydrology or habitats, and internal biogeochemical processes. Measuring infrequently collected grab s les is unlikely to adequately represent nutrient concentrations in such dynamic systems. In contrast, in situ passive s ling techniques, such as the "diffusive gradients in thin films" (DGT) technique, provide time-weighted average analyte concentrations over the entire deployment time. A pair of recently developed DGT techniques for nitrate (A520E-DGT) and ammonium (PrCH-DGT), as well as the Metsorb-DGT technique for phosphate, were used to monitor inorganic nutrients in different freshwater systems (i.e., streams and wetlands) with a range of environmental values and that were affected by different catchment types. Measurements of grab s les collected frequently (1-2 times daily, 8-10 a.m. and 2-4 p.m.) showed that concentrations of NH
Pore water sampling with sediment peepers
Publisher: Elsevier BV
Date: 07-1995
Speciation of dissolved inorganic arsenic by diffusive gradients in thin films: Selective binding of As III by 3-mercaptopropyl-functionalized silica gel
Publisher: American Chemical Society (ACS)
Date: 13-10-2011
DOI: 10.1021/AC202119T
Abstract: A diffusive gradients in thin films (DGT) technique for selectively measuring As(III) utilizes commercially available 3-mercaptopropyl-functionalized silica gel. Deployment of the new technique alongside the Metsorb-DGT for total inorganic arsenic allows the calculation of As(III) directly and As(V) by difference. Uptake of As(III) by mercapto-silica was quantitative and elution with a mixture of 1 mol L(-1) HNO(3) and 0.01 mol L(-1) KIO(3) gave a recovery of 85.6 ± 1.7%. DGT validation experiments showed linear accumulation of As(III) over time (R(2) > 0.998). Accumulation was unaffected by varying ionic strength (0.0001-0.75 mol L(-1) NaNO(3)) and pH (3.5-8.5). Deployment of mercapto-silica DGT and Metsorb DGT in seawater spiked with As(III) and As(V) demonstrated the ability of the combined approach to accurately quantify both species in the presence of potential competing ions. Ferrihydrite DGT, which has been previously reported for the measurement of total inorganic arsenic, was evaluated in seawater and shown to underestimate both As(III) and As(V) at longer deployment times (72 h). Reproducibility of the new mercapto-silica DGT technique was good (relative standard deviations < 9%), and the average method detection limit was sufficiently low to allow quantification of ultratrace concentrations of As(III) (0.03 μg L(-1) 72 h deployment).
Interactive influences of the marine yabby (Trypaea australiensis) and mangrove (Avicennia marina) leaf litter on benthic metabolism and nitrogen cycling in sandy estuarine sediment
Publisher: Springer Science and Business Media LLC
Date: 04-04-2012
Impact of urbanization on coastal wetland structure and function
Publisher: Wiley
Date: 03-03-2006
Evaluation of a simple, inexpensive, in situ sampler for measuring time‐weighted average concentrations of suspended sediment in rivers and streams
Publisher: Wiley
Date: 06-01-2019
DOI: 10.1002/HYP.13353
Neutralizing antibody activity in convalescent sera from infection in humans with SARS-CoV-2 and variants of concern
Publisher: Springer Science and Business Media LLC
Date: 15-10-2021
DOI: 10.1038/S41564-021-00974-0
Abstract: COVID-19 vaccine design and vaccination rollout need to take into account a detailed understanding of antibody durability and cross-neutralizing potential against SARS-CoV-2 and emerging variants of concern (VOCs). Analyses of convalescent sera provide unique insights into antibody longevity and cross-neutralizing activity induced by variant spike proteins, which are putative vaccine candidates. Using sera from 38 in iduals infected in wave 1, we show that cross-neutralizing activity can be detected up to 305 days pos onset of symptoms, although sera were less potent against B.1.1.7 (Alpha) and B1.351 (Beta). Over time, despite a reduction in overall neutralization activity, differences in sera neutralization potency against SARS-CoV-2 and the Alpha and Beta variants decreased, which suggests that continued antibody maturation improves tolerance to spike mutations. We also compared the cross-neutralizing activity of wave 1 sera with sera from in iduals infected with the Alpha, the Beta or the B.1.617.2 (Delta) variants up to 79 days post onset of symptoms. While these sera neutralize the infecting VOC and parental virus to similar levels, cross-neutralization of different SARS-CoV-2 VOC lineages is reduced. These findings will inform the optimization of vaccines to protect against SARS-CoV-2 variants.
Investigating arsenic speciation and mobilization in sediments with DGT and DET: A mesocosm evaluation of oxic-anoxic transitions
Publisher: American Chemical Society (ACS)
Date: 20-03-2012
DOI: 10.1021/ES204484K
Abstract: Mobilization of arsenic from freshwater and estuarine sediments during the transition from oxic to anoxic conditions was investigated using recently developed diffusive s ling techniques. Arsenic speciation and Fe(II) concentrations were measured at high resolution (1-3 mm) with in situ diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques. Water column anoxia induced Fe(II) and As(III) fluxes from the sediment. A correlation between water column Fe(II) and As(III) concentrations was observed in both freshwater (r(s) = 0.896, p < 0.001) and estuarine (r(s) = 0.557, p < 0.001) mesocosms. Porewater s ling by DGT and DET techniques confirmed that arsenic mobilization was associated with the reductive dissolution of Fe(III) (hydr)oxides in the suboxic zone of the sediment a relationship that was visible because of the ability to measure the coincident profiles of these species using combined DGT and DET s lers. The selective measurement of As(III) and total inorganic arsenic by separate DGT s lers indicated that As(III) was the primary species mobilized from the solid phase to the porewater. This measurement approach effectively ruled out substantial As(V) mobilization from the freshwater and estuarine sediments in this experiment. This study demonstrates the capabilities of the DGT and DET techniques for investigating arsenic speciation and mobilization over a range of sediment conditions.
In situ biochar capping is feasible to control ammonia nitrogen release from sediments evaluated by DGT
Publisher: Elsevier BV
Date: 10-2019
Application of a poly(4-styrenesulfonate) liquid binding layer for measurement of Cu2+ and Cd2+ with the diffusive gradients in thin-films technique
Publisher: American Chemical Society (ACS)
Date: 30-04-2003
DOI: 10.1021/AC020658Q
Abstract: A diffusive gradients in thin films (DGT) technique for measuring Cd and Cu is described using, for the first time, a liquid phase binding layer and a dialysis membrane diffusive layer. The binding phase was a 0.020 M solution of poly(4-styrenesulfonate) (PSS) polyelectrolyte using a specially designed DGT deployment device. The binding properties of Cd2+, Cu2+, and a range of alkali and alkaline earth metal ions to the PSS solution were characterized. The PSS behaved like a cation exchanger with preferential binding to Cd2+ (6.0 micromol mL(-1), log K = 9.0) and Cu2+ (2.5 micromol mL(-1), log K = 8.1) under competitive binding conditions. PSS had a substantial binding capacity at pH > 3 and at competitive Na+ concentrations up to 1.0 M. The DGT devices were successfully validated for Cd2+ (accumulated mass vs time r2 = 0.969, recovery compared with predicted values = 98%) and Cu2+ (r2 = 0.980, recovery = 98%) in synthetic lake water (Windermere). Validation was also undertaken for Cu in a spiked local lake water (Parkwood Pond) (r2 = 0.981, recovery = 46%). The low recovery here was due to complexation of Cu by natural organic matter (14 mg C L(-1)). Field deployments of the DGT devices were successful at measuring Cu concentrations of 0.031-0.63 microg L(-1) in local fresh and salt waterways. These DGT-labile measurements were 0.05-39% of the 0.45-microm-filtered Cu values.
Recent advances in ion sensing with conducting polymers
Publisher: Springer Science and Business Media LLC
Date: 21-11-2019
DOI: 10.1186/S42833-019-0001-7
Abstract: Ions are present throughout our environment—from biological systems to agriculture and beyond. Many important processes and mechanisms are driven by their presence and their relative concentration. In order to study, understand and/or control these, it is important to know what ions are present and in what concentration—highlighting the importance of ion sensing. Materials that show specific ion interaction with a commensurate change in measurable properties are the key components of ion sensing. One such type are conducting polymers. Conducting polymers are referred to as ‘active’ because they show observable changes in their electrical and optical (and other) properties in response to changing levels of doping with ions. For ex le, p-type conducting polymers such as poly(3,4-ethylenedioxythiophene) and polypyrrole, can transition from semi-conducting to metallic in response to increasing levels of anions inserted into their structure. Under certain circumstances, conducting polymers also interact with cations—showing their utility in sensing. Herein, recent advances in conducting polymers will be reviewed in the context of sensing ions. The main scope of this review is to critically evaluate our current understanding of ion interactions with conducting polymers and explore how these novel materials can contribute to improving our ion-sensing capabilities.
Determining time-weighted average concentrations of nitrate and ammonium in freshwaters using DGT with ion exchange membrane-based binding layers
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6EM00260A
Abstract: Commercially-available AMI-7001 anion exchange and CMI-7000 cation exchange membranes were utilised as binding layers for DGT measurements of NO 3 –N and NH 4 –N in freshwaters.
Investigation of recreational boats as a source of copper at anchorage sites using time-integrated diffusive gradients in thin film and sediment measurements
Publisher: Elsevier BV
Date: 11-2004
DOI: 10.1016/J.MARPOLBUL.2004.06.012
Abstract: Antifouling paints on small to medium recreational vessels were first recognized as an important source of pollution in the 1970s. One of the principle biocides in these paints is Cu. Results from a field program in the Gold Coast Broadwater, Queensland, demonstrate a clear correlation between recreational boat numbers at anchorage sites and water column Cu concentrations, for both time-integrated 24 h DGT measurements (n=14, r=0.815, p<0.001) and measurements on composite 0.45 mum-filtered grab s les (n=14, r=0.698, p<0.01) collected every 4 h over 24 h. At boat numbers above 30 the 0.45 microm-filterable Cu concentrations were mostly above the relevant guideline value (1.3 microgl(-1)) but the DGT-reactive Cu concentrations were well below this value at all boat numbers studied. For three-day DGT deployments in Moreton Bay, Queensland, correlations between Cu levels and vessel numbers were not observed, possibly because of uncertain estimates of boat numbers. However, using a multi-factorial ANOVA, DGT-reactive Cu concentrations showed a significant effect for 'sites with vessels vs. sites without vessels' (alpha=0.10, p=0.077) and for 's ling period' (non-holiday weekdays, weekends, holiday weekdays, holiday weekends) at alpha=0.10, p=0.02. Cu levels in sediments at the same sites were strongly influenced by fraction of clay (<63 microm) material but also by whether the s les were collected at an anchorage or control site. Results from this study further support the view that Cu emissions from antifouling paints may become an important source in waters with high boat numbers and should be taken into account when designing management instruments for coastal waterways.
Investigating biogenic heterogeneity in coastal sediments with two-dimensional measurements of iron(II) and sulfide
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/EN08059
Abstract: Environmental context. Microbial respiration generally occurs in distinct layers within coastal sediment, producing high porewater iron or sulfide concentrations, although this layering is dramatically modified by the activities of sediment-dwelling organisms. The present study describes use of a new technique to simultaneously measure two-dimensional concentrations of porewater iron and sulfide at millimetre resolution, allowing the patchiness of patterns of microbial respiration in sediment to be clearly observed. The measurements generally supported a conceptual model predicting the effects of animal burrows and seagrass roots on the porewater iron and sulfide distributions, although the addition of organic matter provided some unexpected observations that require further investigation. Abstract. One of the most powerful predictive tools in sediment biogeochemistry is the electron acceptor layering model, which describes the order in which oxidised compounds are reduced by successions of respiring microbial populations, and how this layering is influenced by benthic macro-organism activity. However, techniques allowing convenient determination of heterogeneous distributions of reduced substances, such as iron(II) and sulfide, have been lacking. A combined diffusive gradients in thin films–diffusive equilibrium in thin films technique was used to quantitatively measure the two-dimensional iron(II) and sulfide distributions at high resolution in the vicinity of various sediment features, including macrofauna burrows, particulate organic matter and macrophyte roots. Substantial heterogeneity was observed for both analytes in all probes, especially in the vicinity of seagrass roots and particulate organic matter. Measured distributions tended to follow the general patterns predicted by the tertiary electron acceptor layering model. However, there was unexpected overlap of sulfide and iron(II) distributions at the millimetre to centimetre scale in several s les from different sediments, notably the more complex sediments containing particulate organic matter and seagrass roots. The cause of such overlap is unclear and further study is necessary to elucidate how such distributions can occur.
Characterising the chemical interactions that occur on polyaniline with inverse thin layer chromatography
Publisher: Wiley
Date: 10-1994
Macroinfauna dynamics and sediment parameters of a subtropical estuarine lake-coombabah lake (southern moreton bay, Australia)
Publisher: Coastal Education and Research Foundation
Date: 11-2013
Comparing dissolved reactive phosphorus measured by DGT with ferrihydrite and titanium dioxide adsorbents: Anionic interferences, adsorbent capacity and deployment time
Publisher: Elsevier BV
Date: 07-2011
DOI: 10.1016/J.ACA.2011.04.049
Abstract: Two adsorbents (Metsorb and ferrihydrite) used in binding layers with the diffusive gradients in a thin film technique were evaluated for the measurement of dissolved reactive phosphorous (DRP) in synthetic and natural waters. Possible interferences were investigated with Cl(-) (up to 1.35 mol L(-1)) and SO(4)(2-) (up to 0.056 mol L(-1)) having no affect on either DGT binding layer, and HCO(3)(-) (up to 5.7 mmol L(-1)) having no effect on Metsorb-DGT, over 4 days. However, HCO(3)(-) interfered with the ferrihydrite-DGT measurement at concentrations typical of many natural waters (≥0.7 mmol L(-1)) after a deployment period of 1-2 days. The capacity of the Metsorb binding phase for DGT response was ∼37,000 ng P, whereas the capacities of a low-mass (17.8 mg of adsorbent per DGT s ler) and high-mass (29.2mg of adsorbent per DGT s ler) ferrihydrite binding phase were substantially lower (∼15,000 ng P and ∼25,000 ng P, low-mass and high-mass, respectively). Increasing the capacity of the ferrihydrite adsorbent allowed the ferrihydrite-DGT to be utilized for up to 3 days before interference by HCO(3)(-) was observed. Seawater deployments demonstrated that even high-capacity ferrihydrite-DGT devices underestimated the DRP concentration by 37%, whereas Metsorb-DGT measurements were accurate. The Metsorb-DGT is superior to the ferrihydrite-DGT for determining DRP over deployment times greater than 1 day and in waters with ≥0.7 mmol L(-1) HCO(3)(-). Based on the experience obtained from this detailed validation process, the authors propose a number of key requirements that need to be considered when developing new DGT binding layers, with testing the performance over longer deployment times being critical.
Titanium dioxide-based DGT for measuring dissolved As(V), V(V), Sb(V), Mo(VI) and W(VI) in water
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.TALANTA.2012.11.070
Abstract: A titanium dioxide-based DGT method (Metsorb-DGT) was evaluated for the measurement of As(V), V(V), Sb(V), Mo(VI), W(VI) and dissolved reactive phosphorus (DRP) in synthetic waters. Mass vs. time DGT deployments at pH 6.06 (0.01 mol L(-1) NaNO3) demonstrated linear uptake of all analytes (R(2) ≥ 0.994). Diffusion coefficients measured using a diffusion cell were in reasonable agreement with diffusion coefficients measured using DGT s lers (DCell/DDGT=0.82-1.10), although a systematic difference was apparent. The Metsorb-DGT method was independent of ionic strength (0.001-0.7 mol L(-1) NaNO3 at pH 7.1) for the measurement of all analytes (CDGT/CSol=0.88-1.11) and, with the exception of V(V), the method was independent of pH (3.98-8.24, 0.01 mol L(-1) NaNO3), indicated by CDGT/CSol values in the range 0.88-1.13 for short-term deployments (up to 10h). For V(V) at pH 3.98, Metsorb-DGT underestimated the solution concentration by 17%, presumably due to weak binding of the VO2(+) species. The Metsorb-DGT and ferrihydrite-DGT (in situ precipitated ferrihydrite) methods were compared by deploying s lers in synthetic freshwater (pH 7.20, conductivity 223 μS cm(-1)) and synthetic seawater (pH 8.3. salinity 34.6) for up to four days. For synthetic freshwater, CDGT/CSol values between 0.87-1.17 were obtained for all analytes measured by the Metsorb-DGT method over the deployment period. For ferrihydrite-DGT, CDGT/CSol values between 0.97-1.23 were obtained for As(V), V(V), W(VI) and DRP. However, Mo and Sb(V) showed reduced uptake and CDGT/CSol values were in the range 0.18-1.14 and 0.39-0.98, respectively. In synthetic seawater deployments, Metsorb-DGT was capable of measuring As(V), V(V), Sb(V), W(VI) and DRP for up to 4 days (CDGT/CSol=0.89-1.26), however, this method was not capable of measuring Mo for deployment times >4h (CDGT=0.27-0.72). For ferrihydrite-DGT, CDGT/CSol values in the range 0.92-1.16 were obtained for As(V), V(V) and DRP, however, Mo(VI), Sb(V) and W(VI) could not be measured to within 15% of the solution concentration (CDGT/CSol 0.02-0.83).
Quality criteria in Australian reclaimed water guidelines and effluent discharge licences: How consistent are we?
Publisher: Informa UK Limited
Date: 2004
Application of a cellulose phosphate ion exchange membrane as a binding phase in the diffusive gradients in thin films technique for measurement of trace metals
Publisher: Elsevier BV
Date: 08-2002
Survey of users and providers of recycled water: Quality concerns and directions for applied research
Publisher: Elsevier BV
Date: 12-2002
DOI: 10.1016/S0043-1354(02)00158-6
Abstract: Users and providers of recycled water in Queensland, Australia, were canvassed to ascertain concerns about recycled water quality and directions for applied research. Some 79% of respondents had concerns about recycled water quality including microbiological components, such as viruses, parasites and bacteria, salinity related components, aggregate components, such as pH and solids, nutrients, organic components, including pesticides and endocrine disruptors, as well as quality variability. Relative differences in the proportion of concern for some quality characteristics were observed between the areas of different population density with those from the low population areas being more concerned than those from medium or high areas. Some users and providers observed changes in recycled water quality during distribution including nutrients, chlorine, solids, colour and odour. Some 52% of providers and 19% of current users propose to expand their usage and 30% of non-users propose to commence doing so in the next 5 years. Recycled water quality characteristics identified for applied research included microbiological components, organic components, nutrients and salinity.
Transport across stand-alone conducting polypyrrole membranes containing dodecylsulfate counterions
Publisher: Elsevier BV
Date: 10-1994
Electrochemical chromatography -packings, hardware and mechanisms of interaction
Publisher: Elsevier BV
Date: 05-1991
Diffusive Gradients in Thin Films Reveals Differences in Antimony and Arsenic Mobility in a Contaminated Wetland Sediment during an Oxic-Anoxic Transition
Publisher: American Chemical Society (ACS)
Date: 26-01-2018
Abstract: Antimony (Sb) and arsenic (As) are priority environmental contaminants that often co-occur at mining-impacted sites. Despite their chemical similarities, Sb mobility in waterlogged sediments is poorly understood in comparison to As, particularly across the sediment-water interface (SWI) where changes can occur at the millimeter scale. Combined diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques provided a high resolution, in situ comparison between Sb, As, and iron (Fe) speciation and mobility across the SWI in contaminated freshwater wetland sediment mesocosms under an oxic-anoxic-oxic transition. The shift to anoxic conditions released Fe(II), As(III), and As(V) from the sediment to the water column, consistent with As release being coupled to the reductive dissolution of iron(III) (hydr)oxides. Conversely, Sb(III) and Sb(V) effluxed to the water column under oxic conditions and fluxed into the sediment under anoxic conditions. Porewater DGT-DET depth profiles showed apparent decoupling between Fe(II) and Sb release, as Sb was primarily mobilized across the SWI under oxic conditions. Solid-phase X-ray absorption spectroscopy (XAS) revealed the presence of an Sb(III)-S phase in the sediment that increased in proportion with depth and the transition from oxic to anoxic conditions. The results of this study showed that Sb mobilization was decoupled from the Fe cycle and was, therefore, more likely linked to sulfur and/or organic carbon (e.g., most likely authigenic antimony sulfide formation or Sb(III) complexation by reduced organic sulfur functional groups).
Comparing in situ colorimetric DET and DGT techniques with ex situ core slicing and centrifugation for measuring ferrous iron and dissolved sulfide in coastal sediment pore waters
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.CHEMOSPHERE.2017.08.144
Abstract: In productive coastal sediments the separation between different biogeochemical zones (e.g. oxic, iron(III)-reducing and sulfate-reducing) may be on the scale of millimetres. Conventional measurement techniques simply cannot resolve changes in pore water solute concentrations over such small distances. The diffusive equilibration in thin films (DET) and the diffusive gradients in thin films (DGT) techniques allow in situ determination of pore water solute concentration profiles with one-dimensional profiles and/or two-dimensional distributions on the millimetre scale. Here we compare measurements of pore water iron(II) and sulfide using conventional core s ling (slicing and centrifugation) and colorimetric DET-DGT techniques. DET-DGT s lers were deployed within replicate sediment cores from three different sites, which were processed by slicing and centrifugation following retrieval of the s lers, so that the measurements were approximately co-located. Iron(II) concentrations were determined by DET at all three sites (0.3-262 μmol L
In situ characterization of conducting polymers by measuring dynamic contact angles with Wilhelmy's plate technique
Publisher: Elsevier BV
Date: 02-1995
Use of flathead mullet (Mugil cephalus) in coastal biomonitor studies: Review and recommendations for future studies
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.MARPOLBUL.2013.01.012
Abstract: There has been a widespread world-wide use of flathead mullet, Mugilcephalus, in fish biomonitor studies within the coastal zone. This review summarises this research field, focusing on heavy metals, and considers the implications of the accumulated data. Differences in s ling methodology, tissues analysed and units of reported data provide challenges in assessing and benchmarking these biomonitor studies. The benthic feeding strategy of M.cephalus invariably increases exposure risk relative to middle or upper water column feeders, nevertheless contaminant accumulation via direct and indirect pathways was regulated sufficiently such that toxicants were below food guidelines in most coastal regions (32 of the 49 examined). Human health issues can arise if fish are consumed from heavily industrialised regions. Recommendations are provided for future biomonitoring studies, based on the results for M. cephalus but relevant for fish species more broadly, to provide more comparable data so that managers can benchmark against local conditions.
Comparison of DET, DGT and conventional porewater extractions for determining nutrient profiles and cycling in stream sediments
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9EM00312F
Abstract: Passive s lers measurements, especially DET, contributed to understanding of nitrogen transformations and sediment heterogeneity influenced by benthic microalgae, rooted aquatic plants and/or diel light cycles. Measurement capabilities varied considerably, especially for NH 4 –N.
Optimization of Enzyme Induced Carbonate Precipitation (EICP) as a Ground Improvement Technique
Publisher: American Society of Civil Engineers
Date: 21-02-2020
In situ, high-resolution measurement of labile phosphate in sediment porewater using the DET technique coupled with optimized imaging densitometry
Publisher: Elsevier BV
Date: 12-2020
Decline in recycled water quality during short-term storage in open ponds
Publisher: IWA Publishing
Date: 07-2009
DOI: 10.2166/WH.2009.134
Abstract: Changes were assessed in urban wastewater treatment plant (WWTP) effluent quality during short-term storage in open surface ponds. Water quality was monitored over five years at the inlets and outlets of open storage ponds located at three biological nutrient removal plants. Pond influent temperature, rainfall and sewage inflow were not found to be major factors. However, there was a trend for water temperature to be correlated negatively with nitrogenous nutrient and positively with faecal coliform values. The observed increases in faecal coliforms, nutrients and chemical oxygen demand were most likely caused through avian faecal contamination. These increases challenge the notion that pond storage has a positive or negligible effect on effluent quality. The observed one to two orders of magnitude increase in faecal coliforms may affect reuse scheme viability by limiting the range of uses under Australian water recycling guidelines. Potential improvements to short-term recycled water storage management at WWTPs could include the integration of monitoring requirements in WWTP discharge licences and recycling guidelines and the monitoring of all water quality parameters, including microbiological ones, at the point of entry into the recycled water distribution system, after WWTP storage, rather than directly post-disinfection.
An evaluation of ferrihydrite- and Metsorb™-DGT techniques for measuring oxyanion species (As, Se, V, P): Effective capacity, competition and diffusion coefficients
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.ACA.2013.07.001
Abstract: This study investigated several knowledge gaps with respect to the diffusive gradients in thin films (DGT) technique for measurement of oxyanions (As(III), As(V), Se(IV), Se(VI), PO4(3-), and V(V)) using the ferrihydrite and Metsorb™ binding layers. Elution efficiencies for each binding layer were higher with 1:20 dilutions, as analytical interferences for ICP-MS were minimised. Diffusion coefficients measured by diffusion cell and by DGT time-series experiments were found to agree well and generally agreed with previously reported values, although a range of diffusion coefficients have been reported for inorganic As and Se species. The relative binding affinity for both ferrihydrite and Metsorb™ was PO4(3-) ≈ As(V)>V(V) ≈ As(III)>Se(IV) >>> Se(VI) and effective binding capacities were measured in single ion solutions, and spiked synthetic freshwater and seawater, advising practical decisions about DGT monitoring. Under the conditions tested the performance of both ferrihydrite and Metsorb™ binding layers was directly comparable for As(V), As(III) Se(IV), V(V) and PO4(3-) over a deployment spanning ≤ 2 days for both freshwater and seawater. In order to return quantitative data for several analytes we recommend that the DGT method using either ferrihydrite or Metsorb™ be deployed for a maximum of 2 days in marine waters likely to contain high levels of the most strongly adsorbing oxyanions contaminants. The high pH, the competitive ions present in seawater and the identity of co-adsorbing ions affect the capacity of each binding layer for the analytes of interest. In freshwaters, longer deployment times can be considered but the concentration and identity of co-adsorbing ions may impact on quantitative uptake of Se(IV). This study found ferrihydrite-DGT outperformed Metsorb-DGT while previous studies have found the opposite, with variation in binding materials masses used being a likely reason. Clearly, preparation of both binding layers should always be optimised to produce the highest capacity possible, especially for seawater deployments.
A comparison of mechanical responses for microbial- and enzyme-induced cemented sand
Publisher: Thomas Telford Ltd.
Date: 12-2020
Abstract: The overall effectiveness of bio-cementation techniques such as microbial-induced carbonate precipitation (MICP) or enzyme-induced carbonate precipitation (EICP) can be different due to different sources of urease enzyme and treatment approach used. This paper compares the behaviour of oven-dried MICP and EICP-treated sand from macro- and micro-mechanical point of view with the number of treatment cycles and average calcium carbonate (CaCO 3 ) content used as a comparison basis. The results indicate that in both processes, the calcium carbonate content increased with the number of treatment cycles and led to an improvement in strength (unconfined compressive and splitting tensile strength) and stiffness. For similar average calcium carbonate content, EICP-treated s les showed significantly higher splitting tensile strength (compared to MICP) even though a slightly smaller amount of precipitates were observed at particle contacts through scanning electron microscopy. This indicates, besides the average calcium carbonate content, its distribution along the height of the s le is likely to have a significant contribution towards the strength. X-ray powder diffraction and energy-dispersive X-ray spectroscopy analyses confirmed that precipitated calcium carbonate in both types of treatments were mainly calcite crystals with minor traces of aragonite.
Practical improvements for redox potential (EH) measurements and the application of a multiple-electrode redox probe (MERP) for characterising sediment in situ
Publisher: Elsevier BV
Date: 07-1998
Assessing the uptake of arsenic and antimony from contaminated soil by radish (Raphanus sativus) using DGT and selective extractions
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.ENVPOL.2016.05.027
Abstract: The enrichment of soil arsenic (As) and antimony (Sb) is putting increasing pressure on the environment and human health. The biogeochemical behaviour of Sb and its uptake mechanisms by plants are poorly understood and generally assumed to be similar to that of As. In this study, the lability of As and Sb under agricultural conditions in historically contaminated soils was assessed. Soils were prepared by mixing historically As and Sb-contaminated soil with an uncontaminated soil at different ratios. The lability of As and Sb in the soils was assessed using various approaches: the diffusive gradients in thin films technique (DGT) (as CDGT), soil solution analysis, and sequential extraction procedure (SEP). Lability was compared to the bioaccumulation of As and Sb by various compartments of radish (Raphanus sativus) grown in these soils in a pot experiment. Irrespective of the method, all of the labile fractions showed that both As and Sb were firmly bound to the solid phases, and that Sb was less mobile than As, although total soil Sb concentrations were higher than total soil As. The bioassay demonstrated low bioaccumulation of As and Sb into R. sativus due to their low lability of As and Sb in soils and that there are likely to be differences in their mechanisms of uptake. As accumulated in R. sativus roots was much higher (2.5-21 times) than that of Sb, while the Sb translocated from roots to shoots was approximately 2.5 times higher than that of As. As and Sb in R. sativus tissues were strongly correlated with their labile concentrations measured by DGT, soil solution, and SEP. These techniques are useful measures for predicting bioavailable As and Sb in the historically contaminated soil to R. sativus. This is the first study to demonstrate the suitability of DGT to measure labile Sb in soils.
Interfacial analysis - techniques for the study and characterisation of advanced materials
Publisher: Elsevier BV
Date: 03-1993
Suspended sediment monitoring in alluvial gullies: A laboratory and field evaluation of available measurement techniques
Publisher: Wiley
Date: 19-06-2020
DOI: 10.1002/HYP.13824
INFLUENCE OF SEDIMENT METAL SPIKING PROCEDURES ON COPPER BIOAVAILABILITY AND TOXICITY IN THE ESTUARINE BIVALVE INDOAUSTRIELLA LAMPRELLI
Publisher: Wiley
Date: 09-2009
DOI: 10.1897/08-469.1
Diel fluctuations in solute distributions and biogeochemical cycling in a hypersaline microbial mat from Shark Bay, WA
Publisher: Elsevier BV
Date: 12-2014
Decomposition of jellyfish carrion in situ: Short-term impacts on infauna, benthic nutrient fluxes and sediment redox conditions
Publisher: Elsevier BV
Date: 10-2016
DOI: 10.1016/J.SCITOTENV.2016.05.011
Abstract: Jellyfish often form blooms that persist for weeks to months before they collapse en masse, resulting in the sudden release of large amounts of organic matter to the environment. This study investigated the biogeochemical and ecological effects of the decomposition of jellyfish in a shallow coastal lagoon in New South Wales, Australia. Catostylus mosaicus carrion was added to the surface of shallow sub-tidal sediments and biogeochemical parameters and macrofaunal abundance immediately below the jellyfish carrion were measured over three days. Sediment plots without jellyfish served as controls. Sediment oxygen demand and carbon and nitrogen efflux increased by up to 60-fold in the jellyfish plots, compared to control plots, and dissolved organic nutrient fluxes were more sustained than in previous studies due to the use of fresh rather than frozen biomass. The decomposing jellyfish progressively altered sediment redox conditions, indicated by an increase in porewater iron (II) and sulfide concentrations measured by high-resolution in situ diffusive s lers. Abundance of some macrofaunal taxa in the jellyfish plots decreased relative to controls, however, the abundance of a carnivorous gastropod, which was presumably feeding on the carrion, increased in the jellyfish plots. While jellyfish carrion may be a food source for some macrofauna, low oxygen conditions coupled with the accumulation of toxic dissolved sulfides in the near-surface sediments may explain the overall change in the macroinfaunal community.
Development and evaluation of a diffusive gradients in a thin film technique for measuring ammonium in freshwaters
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.ACA.2015.11.022
Abstract: A new diffusive gradients in a thin film (DGT) technique, using Microlite PrCH cation exchange resin, was developed and evaluated for measuring NH4-N in freshwaters. Microlite PrCH had high uptake (>92.5%) and elution efficiencies (87.2% using 2 mol L(-1) NaCl). Mass vs. time validation experiments over 24 h demonstrated excellent linearity (R(2) ≥ 0.996). PrCH-DGT binding layers had an extremely high intrinsic binding capacity for NH4-N (∼3000 μg). NH4-N uptake was quantitative over pH ranges 3.5-8.5 and ionic strength (up to 0.012 mol L(-1) as NaCl) typical of freshwater systems. Several cations (Na(+), K(+), Ca(2+) and Mg(2+)) were found to compete with NH4-N for uptake by PrCH-DGT, but NH4-N uptake was quantitative over concentration ranges typical of freshwater (up to 0.012 mol L(-1) Na(+), 0.006 mol L(-1) K(+), 0.003 mol L(-1) Ca(2+) and 0.004 mol L(-1) Mg(2+)). Effective diffusion coefficients determined from mass vs. time experiments changed non-linearly with electrical conductivity. Field deployments of DGT s lers with varying diffusive layer thicknesses validated the use of the technique in situ, allowed deployment times to be manipulated with respect to NH4-N concentration, and enable the calculation of the diffusive boundary layer thickness. Daily grab s le NH4-N concentrations were observed to vary considerably independent of major rainfall events, but good agreements were obtained between PrCH-DGT values and mean grab s le measurements of NH4-N (CDGT:CSOLN 0.83-1.3). Reproducibility of DGT measurements in the field was good (relative standard deviation < 11%). Limit of detection was 0.63 μg L(-1) (equivalent to 0.045 μmol L(-1)) based on 24 h deployments.
In situ, high-resolution measurement of dissolved sulfide using diffusive gradients in thin films with computer-imaging densitometry
Publisher: American Chemical Society (ACS)
Date: 24-04-1999
DOI: 10.1021/AC981329U
Abstract: The technique of diffusive gradients in thin films (DGT) has been developed for the measurement of dissolved sulfide. Sulfide species from the s led waters diffuse through a polyacrylamide hydrogel and then react with pale yellow AgI((s)), incorporated at the surface of a second gel, to form black Ag(2)S((s)). The accumulated sulfide can be measured with a conventional purge-and-trap method followed by colorimetry (methylene blue). This enables the dissolved-sulfide concentration to be calculated under suitable conditions. Alternatively, the color change in the accumulating gel can be used to measure sulfide. A conventional flat-bed scanner, allied to imaging software, provided a densitometric measurement that was quantitatively related to the amount of sulfide accumulated. DGT measurements on synthetic solutions accurately determined the sulfide concentration (95% recovery), thereby confirming the unobstructed diffusion of HS(-) through the gel. The accumulated mass was inversely proportional to the diffusion-layer thickness as theoretically predicted. With the selected geometry, the limit of detection of the densitometric procedure for a 24-h deployment was 0.13 μmol L(-)(1), and the maximum concentration measurable was 60 μmol L(-)(1). When used in anoxic lacustrine waters, DGT provided sensible concentrations. It was also used to measure depth profiles at submillimeter resolution in estuarine surface sediments.
Comments on determination of total arsenic using a novel Zn-ferrite binding gel for DGT techniques: Application to the redox speciation of arsenic in river sediments by Gorny et al.
Publisher: Elsevier BV
Date: 03-2016
Development and evaluation of a new diffusive gradients in thin-films technique for measuring organotin compounds in coastal sediment pore water
Publisher: Elsevier BV
Date: 02-2018
DOI: 10.1016/J.TALANTA.2017.09.081
Abstract: Organotins present a toxicological risk to biota in the aquatic environment. Understanding the behaviour of these compounds in sediment is challenging, with sophisticated analytical techniques required for their measurement. We investigated the use of silica-bound sorbents for diffusive gradients in thin-films (DGT) adsorption gels to pre-concentrate five organotins (monobutlytin (MBT), dibutyltin (DBT), tributyltin (TBT), diphenyltin (DPhT), triphenyltin (TPhT)) found frequently in coastal sediment. C
The Effect of Sediment Type and pH-Adjustment on the Porewater Chemistry of Copper- and Zinc-Spiked Sediments
Publisher: Informa UK Limited
Date: 24-12-2009
A new colorimetric DET technique for determining mm-resolution sulfide porewater distributions and allowing improved interpretation of iron(II) co-distributions
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.CHEMOSPHERE.2019.125388
Abstract: Measurement of sulfide in pore waters is critical for understanding biogeochemical processes, especially within coastal sediments. Here we report the development of a new colorimetric DET (diffusive equilibration in thin films) technique for determining mm-resolution, two-dimensional sulfide distributions in sediment pore waters. This colorimetric sulfide DET method was based on the standard spectrophotometric methylene blue assay, but modified to allow quantitation of sulfide by computer imaging densitometry. The method detection and effective upper measurement limits of the optimised technique were 3.7 and 1000 μmol L
DGT and selective extractions reveal differences in arsenic and antimony uptake by the white icicle radish (Raphanus sativus)
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.ENVPOL.2019.113815
Abstract: Increasing soil contamination of arsenic (As) and antimony (Sb) is posing a serious concern to human health. Due to insufficient studies on Sb, the biogeochemical behaviour and plant uptake of Sb are assumed to be similar to that of As. As part of extensive research unravelling As and Sb biogeochemistry and plant uptake, the diffusive gradients in thin films (DGT) technique and sequential extraction procedure (SEP) were applied to evaluate As and Sb uptake by the white icicle radish (Raphanus sativus) cultivated in diluted cattle dip soils contaminated with As only and diluted mining soils contaminated with both As and Sb under agricultural conditions. Labile As and Sb in these soils measured by DGT (C
Molecular recognition using conducting polymers: Basis of an electrochemical sensing technology: Plenary lecture
Publisher: Royal Society of Chemistry (RSC)
Date: 1993
DOI: 10.1039/AN9931800329
Theoretical and experimental analysis of peeper equilibration dynamics
Publisher: American Chemical Society (ACS)
Date: 08-04-1998
DOI: 10.1021/ES970815G
Diurnal shifts in co-distributions of sulfide and iron(II) and profiles of phosphate and ammonium in the rhizosphere of Zostera capricorni
Publisher: Elsevier BV
Date: 12-2012
Antimony and arsenic exhibit contrasting spatial distributions in the sediment and vegetation of a contaminated wetland
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.CHEMOSPHERE.2017.03.142
Abstract: Antimony is a priority environmental contaminant that is relatively poorly studied compared to other trace metal(loid)s. In particular, the behaviour of antimony in wetland sediments, where anaerobic conditions often dominate, has received considerably less attention compared to well-drained terrestrial soil environments. Here we report the results of a spatial assessment of antimony in the sediments and vegetation of a freshwater wetland exposed to stibnite tailings for the past forty years. The concentration of antimony in the sediment decreased rapidly with distance from the tailings deposit, from a maximum of ∼22,000 mg kg
Distribution of nutrients in surface and sub-surface sediments of Coombabah Lake, southern Moreton Bay (Australia)
Publisher: Elsevier BV
Date: 05-2007
Protecting Water Quality in Urban Estuaries: Australian Case Studies
Publisher: Elsevier
Date: 2019
A ferricyanide-mediated activated sludge bioassay for fast determination of the biochemical oxygen demand of wastewaters
Publisher: Elsevier BV
Date: 12-2010
DOI: 10.1016/J.WATRES.2010.07.042
Abstract: Activated sludge was successfully incorporated as the biocatalyst in the fast, ferricyanide-mediated biochemical oxygen demand (FM-BOD) bioassay. Sludge preparation procedures were optimized for three potential biocatalysts aeration basin mixed liquor, aerobic digester sludge and return activated sludge. Following a 24h starving period, the return activated sludge and mixed liquor sludges reported the highest oxidative degradation of a standard glucose/glutamic acid (GGA) mixture and the return activated sludge also recorded the lowest endogenous FM-respiration rate. Dynamic working ranges up to 170 mg BOD(5)L(-1) for OECD standard solutions and 300mg BOD(5)L(-1) for GGA were obtained. This is a considerable improvement upon the BOD(5) standard assay and most other rapid BOD techniques. Time-series ferricyanide-mediated oxidation of the OECD(170) standard approached that of the GGA(198) standard after 3-6h. This is noteworthy given the OECD standard is formulated as a synthetic sewage analogue. A highly significant correlation with the BOD(5) standard method (n=35, p<0.001, R=0.952) was observed for a wide ersity of real wastewater s les. The mean degradation efficiency was indistinguishable from that observed for the BOD(5) assay. These results demonstrate that the activated sludge FM-BOD assay may be used for simple, same-day BOD analysis of wastewaters.
A systematic determination of diffusion coefficients of trace elements in open and restricted diffusive layers used by the diffusive gradients in a thin film technique
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.ACA.2015.07.027
Abstract: A systematic comparison of the diffusion coefficients of cations (Al, Cd, Co, Cu, Mn, Ni, Pb, Zn) and oxyanions (Al, As, Mo, Sb, V, W) in open (ODL) and restricted (RDL) diffusive layers used by the DGT technique was undertaken. Diffusion coefficients were measured using both the diffusion cell (Dcell) method at pH 4.00 and the DGT time-series (D(DGT)) method at pH 4.01 and 7.04 (pH 8.30 was used instead of 7.04 for Al) using the Chelex-Metsorb mixed binding layer. The performance of Chelex-Metsorb as a new DGT binding layer for Al uptake was also evaluated for the first time. Reasonable agreement was observed between D(cell) and D(DGT) measurements for both ODL and RDL, except for V and W. The ratios of D(cell)/D(DGT) for V of 0.44 and 0.39, and for W of 0.66 and 0.63 with ODL and RDL respectively, were much lower due to the formation of a high proportion of polyoxometalate species at the higher concentrations required with the D(cell) measurements. This is the first time that D values have been reported for several oxyanions using RDL. Except for Al at pH 8.30 with ODL, all D(DGT) measurements were retarded relative to diffusion coefficients in water (DW) for both diffusive hydrogels. Diffusion in RDL was further retarded compared with ODL, for all elements (0.66-0.78) with both methods. However, the degree of retardation observed changed for cations and anions at each pH. At pH 7.04 cations had a slightly higher D(DGT) and oxyanions had a slightly lower D(DGT) than at pH 4.01 for both ODL and RDL. It is proposed that this is due to partial formation of acrylic acid functional groups (pKa ≈4.5), which would be fully deprotonated at pH 7.04 (negative) and mostly protonated at pH 4.01 (neutral). As Al changes from being cationic at pH 4.01 to anionic at pH 8.30 the results were more complex.
A sensitive ferricyanide-mediated biochemical oxygen demand assay for analysis of wastewater treatment plant influents and treated effluents
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.WATRES.2012.11.010
Abstract: Representative and fast monitoring of wastewater influent and effluent biochemical oxygen demand (BOD) is an elusive goal for the wastewater industry and regulatory bodies alike. The present study describes a suitable assay, which incorporates activated sludge as the biocatalyst and ferricyanide as the terminal electron acceptor for respiration. A number of different sludges and sludge treatments were investigated, primarily to improve the sensitivity of the assay. A limit of detection (LOD) (2.1 mg BOD₅ L⁻¹) very similar to that of the standard 5-day BOD₅ method was achieved in 4 h using raw influent sludge that had been cultured overnight as the biocatalyst. Reducing the microbial concentration was the most effective means to improve sensitivity and reduce the contribution of the sludge's endogenous respiration to total ferricyanide-mediated (FM) respiration. A strong and highly significant relationship was found (n = 33 R = 0.96 p < 0.001 slope = 0.94) between BOD₅ and FM-BOD equivalent values for a erse range of s les including wastewater treatment plant (WWTP) influent and treated effluent, as well as several grey water s les. The activated sludge FM-BOD assay presented here is an exceptional surrogate method to the standard BOD₅ assay, providing representative, same-day BOD analysis of WWTP s les with a comparable detection limit, a 4-fold greater analytical range and much faster analysis time. The industry appeal of such an assay is tremendous given that ~90% of all BOD₅ analysis is dedicated to measurement of WWTP s les, for which this assay is specifically designed.
The influence of small-scale circum-neutral pH change on Cu-bioavailability and toxicity to an estuarine bivalve (Austriella cf plicifera) in whole-sediment toxicity tests
Publisher: Elsevier BV
Date: 11-2008
Evaluation of the DGT technique for selective measurement of aluminium and trace metal concentrations in an acid drainage-impacted coastal waterway
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6EM00276E
Abstract: DGT s lers with different binding layers (Chelex, Metsorb and mixed Chelex–Metsorb) were evaluated for measurement of Al and trace metals in four natural waters with a range of pH.
Preparation and characterisation of a poly(acrylamidoglycolic acid-co-acrylamide) hydrogel for selective binding of Cu2+ and application to diffusive gradients in thin films measurements
Publisher: Elsevier BV
Date: 08-2002
Cu and Zn concentration gradients created by dilution of pH neutral metal-spiked marine sediment: A comparison of sediment geochemistry with direct methods of metal addition
Publisher: American Chemical Society (ACS)
Date: 18-03-2008
DOI: 10.1021/ES702673W
Use of inverse thin layer chromatography with amino acids to characterize molecular interactions on conducting polymers
Publisher: Wiley
Date: 1992
Evaluation of the in situ, time-integrated DGT technique by monitoring changes in heavy metal concentrations in estuarine waters
Publisher: Elsevier BV
Date: 07-2007
DOI: 10.1016/J.ENVPOL.2006.10.027
Abstract: Various natural and anthropogenic processes influence heavy metal concentrations within estuaries. In situ, time-integrated DGT measurements made over concurrent tidal phases found significantly higher concentrations of Cu (probability p=0.017), Zn (p=0.003) and Ni (p=0.003) during the flood phase, because the incoming tide passes several point sources. DGT-reactive Cu concentrations significantly decreased with increased tidal-flushing and vice versa within a marina (correlation r=-0.788, p=0.02). DGT measurements also recorded significant increases in Cu (4 out of 4 sites, p<0.001) and Zn (3 out of 4 sites, p< or =0.015) after a 24 mm rainfall event. Finally, DGT-reactive Cu increased significantly (p<0.001) during peak boating times, due to increased numbers of Cu-antifouled boats. This study demonstrates that, with judicious selection of deployment times, DGT measurements enable changes in heavy metal concentrations to be related to various cycles and events within estuaries.
Passive sampling methods for contaminated sediments: State of the science for metals
Publisher: Wiley
Date: 27-01-2004
DOI: 10.1002/IEAM.1502
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Discovery Projects - Grant ID: DP0559935
Start Date: 2005
End Date: 12-2007
Amount: $240,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP0882894
Start Date: 08-2008
End Date: 08-2011
Amount: $150,000.00
Funder: Australian Research Council
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