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Cao H, Bu Q, Li Q, Yang L, Tang J, Yu G. Evaluation of the DGT passive samplers for integrating fluctuating concentrations of pharmaceuticals in surface water. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 926:172067. [PMID: 38565352 DOI: 10.1016/j.scitotenv.2024.172067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 02/24/2024] [Accepted: 03/26/2024] [Indexed: 04/04/2024]
Abstract
Diffusive gradients in thin films (DGTs) have been well-documented for the measurement of a broad range of organic pollutants in surface water. However, the performance has been challenged by the inherent periodic concentration fluctuations for most organic pollutants. Therefore, there is an urgent need to assess the true time-weighted average (TWA) concentration based on fluctuating concentration profiles. The study aimed to evaluate the responsiveness of DGT and accuracy of TWA concentrations, considering various concentration fluctuating scenarios of 20 pharmaceuticals in surface water. The reliability and accuracy of the TWA concentrations measured by the DGT were assessed by comparison with the sum of cumulative mass of DGT exposed at different stages over the deployment period. The results showed that peak concentration duration (1-5 days), peak concentration fluctuation intensity (6-20 times), and occurrence time of peak concentration fluctuation (early, middle, and late stages) have minimal effect on DGT's response to most target pharmaceutical concentration fluctuations (0.8 < CDGT/CTWA < 1.2). While the downward-bent accumulations of a few pharmaceuticals on DGT occur as the sampling time increases, which could be accounted for by capacity effects during a long-time sampling period. Additionally, the DGT device had good sampling performance in recording short fluctuating concentrations from a pulse event returning to background concentrations with variable intensity and duration. This study revealed a satisfactory capacity for the evaluation of the TWA concentration of pharmaceuticals integrated over the period of different pulse deployment for DGT, suggesting that this passive sampler is ideally suited as a monitoring tool for field application. This study represents the first trial for evaluating DGT sampling performance for pharmaceuticals with multiple concentration fluctuating scenarios over time, which would be valuable for assessing the pollution status in future monitoring campaign.
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Affiliation(s)
- Hongmei Cao
- School of Chemical & Environmental Engineering, China University of Mining & Technology-Beijing, Beijing 100083, PR China; School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen 518055, PR China
| | - Qingwei Bu
- School of Chemical & Environmental Engineering, China University of Mining & Technology-Beijing, Beijing 100083, PR China.
| | - Qingshan Li
- School of Chemical & Environmental Engineering, China University of Mining & Technology-Beijing, Beijing 100083, PR China
| | - Lei Yang
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Science, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Jianfeng Tang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, PR China
| | - Gang Yu
- Advanced Interdisciplinary Institute of Environment and Ecology, Beijing Normal University (Zhuhai Campus), Zhuhai 519087, PR China
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2
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Dong F, Ge F, Zhao X, Sun D, Ren S, Wang Y, Tan F. Measurement of perfluoroalkyl substances in drinking water sources by DGT sampler with a novel fluorinated graphite binding gel. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169658. [PMID: 38159764 DOI: 10.1016/j.scitotenv.2023.169658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024]
Abstract
Extensive use of per- and polyfluoroalkyl substances (PFASs) has resulted in their widespread presence in natural waters. Concern for public health requires reliable measurement methods for determining their distribution and risks. Here, a sampling method based on diffusive gradients in thin films (DGT) was developed for measuring PFASs in drinking water sources. Fluorinated graphite (FG) particles were used to prepare the DGT binding gel for selective enrichment of trace PFASs in an aqueous environment. The FG-DGT method did not show sensitivity to relevant environmental parameters including pH (5.0-9.0), ionic strength (0.001-0.5 M), or DOM concentration (0-30 mg/L). The FG-DGT had enough capacity for deployment of up to four months. Six traditional and emerging PFASs including PFOS, PFOA, PFHpA, PFHxS, PFNA, and 6:2 FTSA at the ng/L level were detected in two major reservoirs serving as public drinking water sources by FG-DGT method coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS). PFOA appeared at the highest observed concentrations in the drinking water sources. The research demonstrates that FG-DGT is an effective and efficient tool for monitoring PFASs in drinking water.
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Affiliation(s)
- Fan Dong
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Fan Ge
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Xinting Zhao
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Daming Sun
- Dalian Hydrological Bureau of Liaoning Province, Dalian 116023, China
| | - Suyu Ren
- School of Environmental and Material Engineering, Yantai University, Yan Tai 264005, China
| | - Yan Wang
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Feng Tan
- Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
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3
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Yang D, Chen H, Sun H, Luo J, Li Y. Validation and Assessment of Diffusive Gradients in Thin-Films (DGT) Technique for Measuring Nutrients in Taihu Lake Water with Algae Bloom. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2022; 108:943-948. [PMID: 35124706 DOI: 10.1007/s00128-022-03470-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
DGT (diffusive gradients in thin films) technique has been developed for measuring nitrogen in freshwaters and applied to assess the bioavailability of phosphorus in soils/sediments. These two elements are the main nutrients causing algae bloom, but DGT has never been used in the field water conditions with algae bloom. In our study, a pair of DGT devices were used in comparison with grab sampling to characterize the performance of this technique to measure labile NO3-N, NH4-N, and PO4-P concentrations in algae-cultivated Taihu Lake water. The results showed that DGT measurement was highly affected by algae bloom and the environmental conditions using the current assemblies, especially for NH4-N measurement. For in situ measurement of nutrients in the real environment, an improvement to the DGT technique is required. The comprehensive assessment of the level of eutrophication needs to consider a variety of environmental factors rather than just the concentration of nutrients.
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Affiliation(s)
- Danxing Yang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu, 210023, China
| | - Haiyi Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu, 210023, China
| | - Haitao Sun
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu, 210023, China
| | - Jun Luo
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu, 210023, China
| | - Yanying Li
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Jiangsu, 210023, China.
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4
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Corbett T, Hartland A, Henderson W, Rys G, Schipper LA. The temperature and flow dependence of nitrate concentration and load estimates based on diffusive gradients in thin films. JOURNAL OF ENVIRONMENTAL QUALITY 2022; 51:250-259. [PMID: 34993967 DOI: 10.1002/jeq2.20323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 12/20/2021] [Indexed: 06/14/2023]
Abstract
Concentrations determined using diffusive gradients in thin films (DGT) have been used to derive time-averaged loads in streams and rivers. However, DGT provide time-weighted average concentrations that assume the independence of concentration and flow. Additionally, dynamic and coordinated changes in temperature, flow, and concentration are potential sources of bias in concentration and load calculations. We modeled scenarios in which temperature and flow were correlated to varying degrees with concentration and evaluated the consequences for DGT concentration and load calculations. As the correlation between solution flow and concentration moved toward 1 and -1, the load determined by DGT either overestimated or underestimated the actual load by as much as 30%. In DGT-based load estimates, the degree of potential bias should be assessed, and the concentration-flow relation should be characterized. As the correlation of analyte concentration and temperature approached 1 and -1, the deviation of the concentration determined by DGT from the actual concentration increased. In most cases, this bias was < 2%; however, if the changes in concentration and temperature were large (∼10 mg L-1 and ∼10 °C), the bias exceeded 5%. Concentration and temperature are unlikely to be perfectly or strongly correlated or anti-correlated in natural systems and thus should not affect the accuracy of DGT concentration calculations in most circumstances. The more solution temperature, flow, and concentration were uncorrelated, the closer DGT-derived concentration and load were to the actual solution concentration and load.
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Affiliation(s)
- Thomas Corbett
- School of Science, The Univ. of Waikato, Hamilton, 3216, New Zealand
- Environmental Research Institute, The Univ. of Waikato, Hamilton, 3216, New Zealand
| | - Adam Hartland
- School of Science, The Univ. of Waikato, Hamilton, 3216, New Zealand
- Environmental Research Institute, The Univ. of Waikato, Hamilton, 3216, New Zealand
| | - William Henderson
- School of Science, The Univ. of Waikato, Hamilton, 3216, New Zealand
| | - Gerald Rys
- Ministry for Primary Industries, Wellington, 6011, New Zealand
| | - Louis A Schipper
- School of Science, The Univ. of Waikato, Hamilton, 3216, New Zealand
- Environmental Research Institute, The Univ. of Waikato, Hamilton, 3216, New Zealand
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5
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Wang P, Challis JK, He ZX, Wong CS, Zeng EY. Effects of biofouling on the uptake of perfluorinated alkyl acids by organic-diffusive gradients in thin films passive samplers. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:242-251. [PMID: 35015011 DOI: 10.1039/d1em00436k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
While organic-diffusive gradients in thin films (o-DGT) passive samplers have been used to assess organic contaminants in water, the effects of biofouling on accurate analyte quantification by o-DGT are poorly understood. We evaluated the effects of biofouling on the uptake of six common perfluoroalkyl substances (PFAS) using a previously developed polyacrylamide-WAX (weak anion exchange) o-DGT without a filter membrane. Linear uptake (R2 > 0.91) over 21 days was observed in fouled samplers. The measured sampling rates (Rs) and accumulated masses of PFAS in pre-fouled o-DGT were significantly lower (p < 0.05, 20-39% relative error) than in control-fouled samplers. However, compared to clean o-DGT (no biofouling), the Rs of most PFAS in control-fouled samplers (i.e., those with clean diffusive and binding gels initially) were not affected by biofouling. Under flowing (∼5.8 cm s-1) and static conditions, the measured diffusive boundary layer (DBL) thicknesses for clean o-DGT were 0.016 and 0.082 cm, respectively, whereas the effective in situ biofilm thicknesses for fouled o-DGT were 0.018 and 0.14 cm, respectively. These results suggest that biofilm growth does not have significant effects on target PFAS sampling by o-DGT under typical flowing conditions (≥2 cm s-1). However, rapid surface growth of biofilm on o-DGT deployed in quiescent waters over long periods of time may exacerbate the adverse effects of biofilms, necessitating the estimation of biofilm thickness in situ. This study provides new insights for evaluating the capability of o-DGT samplers when biofilm growth can be significant.
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Affiliation(s)
- Po Wang
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China.
| | - Jonathan K Challis
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada
| | - Zi-Xuan He
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China.
| | - Charles S Wong
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China.
- Southern California Coastal Water Research Project Authority, Costa Mesa CA 92626, USA
| | - Eddy Y Zeng
- Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China.
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6
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Huang J, Hills J, Teasdale PR, Panther JG, Wang F, Welsh DT. Evaluation of the Chelex-DGT technique for the measurement of rare earth elements in the porewater of estuarine and arine sediments. Talanta 2021; 230:122315. [PMID: 33934780 DOI: 10.1016/j.talanta.2021.122315] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 03/11/2021] [Accepted: 03/12/2021] [Indexed: 11/26/2022]
Abstract
This study describes the validation of a diffusive gradients in thin film (DGT) technique for determining lanthanide rare earth elements (REEs) and in situ measurements of REEs in sediment pore waters. Laboratory experiments demonstrated that Chelex-100 binding layers had uptake efficiencies ranging from 78.0% to 92.3% for all REEs. An eluent of 1 mol L-1 HNO3 was optimal with elution efficiencies >80% for all REEs. Mass versus time experiments confirmed that DGT uptake was linear for all REEs at pH 8.1, 6.6 and 3.9 over a period of 3-4 days. Diffusion coefficients (D) for all REEs were derived from these experiments using the slopes of the linear regressions. D values varied with pH but were generally similar to values reported previously. The Chelex-100 DGT technique from this study is highly sensitive for the measurement of REE concentrations with detection limits ranging from 1.8 to 45 ng L-1 based on 72 h deployments allowing measurements of natural trace REE levels. Chelex-100 DGT devices were deployed in estuarine and marine sediments over a period of 72 h and most REE porewater concentrations (50-10,410 ng L-1) were successfully measured. Individual depth profiles of REEs showed a complex response, with many peaks and troughs suggesting a high degree of sediment heterogeneity. Depth-averaged REE concentrations showed a typical zig-zag distribution, although patterns varied between sediment types, after the REEs were normalised using the Queensland Mud Composite shale reference. The Chelex-100 DGT technique therefore shows promise for REE measurements in sediments.
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Affiliation(s)
- Jianyin Huang
- Scarce Resources and Circular Economy (ScaRCE), STEM, University of South Australia, UniSA, SA, 5095, Australia; Future Industries Institute, University of South Australia, SA, 5095, Australia.
| | - Jodie Hills
- Environmental Futures Research Institute, School of Environment and Science, Griffith University, Gold Coast Campus, QLD, 4215, Australia
| | - Peter R Teasdale
- Scarce Resources and Circular Economy (ScaRCE), STEM, University of South Australia, UniSA, SA, 5095, Australia; Future Industries Institute, University of South Australia, SA, 5095, Australia
| | - Jared G Panther
- Environmental Futures Research Institute, School of Environment and Science, Griffith University, Gold Coast Campus, QLD, 4215, Australia
| | - Feiyue Wang
- Centre for Earth Observation Science, Department of Environment and Geography, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada
| | - David T Welsh
- Future Industries Institute, University of South Australia, SA, 5095, Australia; Environmental Futures Research Institute, School of Environment and Science, Griffith University, Gold Coast Campus, QLD, 4215, Australia
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7
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Sans-Duñó J, Cecilia J, Galceran J, Puy J. Availability of metals to DGT devices with different configurations. The case of sequential Ni complexation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 779:146277. [PMID: 33744567 DOI: 10.1016/j.scitotenv.2021.146277] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 02/27/2021] [Accepted: 02/28/2021] [Indexed: 06/12/2023]
Abstract
The analytical technique DGT (Diffusive Gradients in Thin-films) is able to gain access to a wealth of information by carefully interpreting accumulation data from passive samplers with different configurations (i.e. different thicknesses of its constituent layers). A set of DGT devices were simultaneously deployed in solutions of Ni and nitrilotriacetic acid (NTA) of different concentrations to measure the availability of Ni in these solutions. Accumulations indicate that the availability of Ni depends on both the thickness of the resin and the thickness of the diffusive gel. In both cases, the lability degree increases as the thickness increases. As the formation of successive complexes (such as Ni(NTA)2) proceeds, the availability of the metal decreases, which is quantitatively explained by reducing the formulation to a case with only one complex, but with an effective dissociation rate constant that decreases as the concentration of NTA increases. Simple analytical expressions are reported to quantify the lability degree in the different DGT configurations. These results indicate that a set of different DGT devices can characterize the availability of a cation in a natural sample with uptake processes at different spatial or time scales. Alternatively, and from a more fundamental point of view, information on speciation, mobilities and labilities of the species present in natural samples can be obtained with a set of DGT configurations.
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Affiliation(s)
- Jordi Sans-Duñó
- Departament de Química, Universitat de Lleida and AGROTECNIO-CERCA, Rovira Roure 191, 25198 Lleida, Spain
| | - Joan Cecilia
- Departament de Matemàtica, Universitat de Lleida and AGROTECNIO-CERCA, Rovira Roure 191, 25198 Lleida, Spain
| | - Josep Galceran
- Departament de Química, Universitat de Lleida and AGROTECNIO-CERCA, Rovira Roure 191, 25198 Lleida, Spain
| | - Jaume Puy
- Departament de Química, Universitat de Lleida and AGROTECNIO-CERCA, Rovira Roure 191, 25198 Lleida, Spain.
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8
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Arias DM, Teasdale PR, Doolette CL, Lombi E, Farquhar S, Huang J. Development and evaluation of a new colorimetric DGT technique for the 2D visualisation of labile phosphate in soils. CHEMOSPHERE 2021; 269:128704. [PMID: 33220985 DOI: 10.1016/j.chemosphere.2020.128704] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 10/15/2020] [Accepted: 10/18/2020] [Indexed: 06/11/2023]
Abstract
A new colorimetric technique for the measurement of labile phosphate in soils using the diffusive gradients in thin films (DGT) technique was developed in this study. This technique can determine the mass of phosphate accumulated on the precipitated Zr-oxide based binding gel by forming the blue colour following the standard molybdate-ascorbic acid method. The optimal reaction temperature and coloration time were 20 °C (room temperature) and 26 min. After determining a well-fitted calibration equation, the technique was able to measure phosphate concentration up to 2.5 mg/L for 24 h deployment with a detection limit of 10.1 μg/L. Two-dimensional quantitative visualisation of phosphate diffusion in three phosphorus (P) fertilised soils were obtained using the colorimetric technique. The results from the colorimetric DGT technique were compared to the elution DGT technique and Colwell P extraction. The DGT techniques (colorimetric and elution) and Colwell P measurements demonstrated similar patterns of phosphate diffusion in soil. Both DGT techniques showed similar phosphate concentration along the concentric rings around the fertiliser application. A new, convenient, and fast DGT colorimetric technique was developed, and successfully used to measure the distribution of potentially available phosphate in soils. The new technique is less laborious than current techniques as it does not require any pre-treatment of the binding gel layers or heating during scanning, thus providing faster results. Therefore, the technique may be more suitable for in-field applications and can be used to investigate the in situ diffusion of potentially available phosphate from fertilisers, and relate this to the plant uptake of P.
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Affiliation(s)
- David Macias Arias
- University of South Australia, UniSA STEM, Scarce Resources and Circular Economy (ScaRCE), SA, 5095, Australia; School of Civil Engineering (ETSICCP), Universitat Politècnica de València, Camino de Vera S/n, E-46022, Valencia, Spain
| | - Peter R Teasdale
- University of South Australia, UniSA STEM, Scarce Resources and Circular Economy (ScaRCE), SA, 5095, Australia; University of South Australia, Future Industries Institute, SA, 5095, Australia
| | - Casey L Doolette
- University of South Australia, Future Industries Institute, SA, 5095, Australia
| | - Enzo Lombi
- University of South Australia, Future Industries Institute, SA, 5095, Australia
| | - Sarah Farquhar
- University of South Australia, UniSA STEM, Scarce Resources and Circular Economy (ScaRCE), SA, 5095, Australia
| | - Jianyin Huang
- University of South Australia, UniSA STEM, Scarce Resources and Circular Economy (ScaRCE), SA, 5095, Australia; University of South Australia, Future Industries Institute, SA, 5095, Australia.
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9
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O'Connor Šraj L, Almeida MIGS, Sharp SM, McKelvie ID, Morrison R, Kolev SD. Monitoring of ammonia in marine waters using a passive sampler with biofouling resistance and neural network-based calibration. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 267:115457. [PMID: 32889515 DOI: 10.1016/j.envpol.2020.115457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/15/2020] [Accepted: 08/17/2020] [Indexed: 06/11/2023]
Abstract
A biofouling resistant passive sampler for ammonia, where the semi-permeable barrier is a microporous hydrophobic gas-diffusion membrane, has been developed for the first time and successfully applied to determine the time-weighted average concentration of ammonia in estuarine and coastal waters for 7 days. Strategies to control biofouling of the membrane were investigated by covering it with either a copper mesh or a silver nanoparticle functionalised cotton mesh, with the former approach showing better performance. The effects of temperature, pH and salinity on the accumulation of ammonia in the newly developed passive sampler were studied and the first two parameters were found to influence it significantly. A universal calibration model for the passive sampler was developed using the Group Method Data Handling algorithm based on seawater samples spiked with known concentrations of total ammonia under conditions ranging from 10 to 30 °C, pH 7.8 to 8.2 and salinity 20 to 35. The newly developed passive sampler is affordable, user-friendly, reusable, sensitive, and can be used to detect concentrations lower than the recently proposed guideline value of 160 μg total NH3-N L-1, for a 99% species protection level, with the lowest concentration measured at 17 nM molecular NH3 (i.e., 8 μg total NH3-N L-1 at pH 8.0 and 20 °C). It was deployed at four field sites in the coastal waters of Nerm (Port Phillip Bay), Victoria, Australia. Good agreement was found between molecular ammonia concentrations obtained with passive and discrete grab sampling methods (relative difference, - 12% to - 19%).
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Affiliation(s)
| | | | - Simon M Sharp
- Centre for Aquatic Pollution Identification and Management (CAPIM), The University of Melbourne, Victoria, 3010, Australia
| | - Ian D McKelvie
- School of Chemistry, The University of Melbourne, Victoria, 3010, Australia
| | - Richard Morrison
- School of Chemistry, The University of Melbourne, Victoria, 3010, Australia
| | - Spas D Kolev
- School of Chemistry, The University of Melbourne, Victoria, 3010, Australia
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10
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Zhu X, Ma J. Recent advances in the determination of phosphate in environmental water samples: Insights from practical perspectives. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2020.115908] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Corbett TDW, Dougherty H, Maxwell B, Hartland A, Henderson W, Rys GJ, Schipper LA. Utility of 'Diffusive Gradients in Thin-Films' for the measurement of nitrate removal performance of denitrifying bioreactors. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 718:135267. [PMID: 31859060 DOI: 10.1016/j.scitotenv.2019.135267] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/08/2019] [Accepted: 10/27/2019] [Indexed: 06/10/2023]
Abstract
The increase in environmental nutrient availability as a result of human activities has necessitated the development of mitigation strategies for nutrient removal, such as nitrate. Current methods for determining the efficiency of different mitigation strategies required measurement of changes in nitrate concentrations, however, these methods can be expensive or do not account fully for the temporal variability of nitrate concentration. This study evaluated the utility of Diffusive Gradients in Thins-Films (DGT) for determining nitrate removal in two denitrifying bioreactors, and compared DGT performance to traditional approaches for determining performance, including high and low frequency water grab sampling. The binding layer was produced using the Purolite® A520E anion exchange resin. The uptake and elution efficiencies were 98.8% and 93.4% respectively. DGTs of three material diffusion layer thicknesses were placed in piezometers along longitudinal transects, to enable calculation of the diffusive boundary layer and provide replicates. These were removed after 16, 24 and 36 h, and the accumulated nitrate masses were extracted and quantified to calculate nitrate concentration. Concentrations were subsequently utilised to calculate nitrate removal rates in both bioreactors. Grab samples were taken at 30 and 60 min intervals over those periods, nitrate concentrations were also measured to determine nitrate removal. DGTs provided nitrate removal rates at bioreactor site one (controlled flow, wastewater treatment) of 14.83-30.75 g N m-3 d-1, and 1.22-3.63 g N m-3 d-1 at site two (variable flow, agricultural run-off). DGT determined nitrate concentrations and removal rates were in strong accordance with high frequency grab sampling, but data collection via DGTs was considerably easier. Utilising DGTs for the measurement of bioreactor performance overcame many of the challenges associated with high frequency grab sampling, and other methods, such as accounting for temporal variation in nitrate concentration and reduced analytical requirements.
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Affiliation(s)
- Thomas D W Corbett
- Faculty of Science and Engineering, The University of Waikato, Hamilton 3216, New Zealand.
| | - Hannah Dougherty
- Faculty of Science and Engineering, The University of Waikato, Hamilton 3216, New Zealand
| | - Bryan Maxwell
- North Carolina State University, Raleigh, NC 27695, USA
| | - Adam Hartland
- Environmental Research Institute, The University of Waikato, Hamilton 3216, New Zealand
| | - William Henderson
- Faculty of Science and Engineering, The University of Waikato, Hamilton 3216, New Zealand
| | - Gerald J Rys
- Ministry for Primary Industries, Wellington 6011, New Zealand
| | - Louis A Schipper
- Faculty of Science and Engineering, The University of Waikato, Hamilton 3216, New Zealand
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12
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Noh S, Kim YH, Kim H, Seok KS, Park M, Bailon MX, Hong Y. The performance of diffusive gradient in thin film probes for the long-term monitoring of trace level total mercury in water. ENVIRONMENTAL MONITORING AND ASSESSMENT 2019; 192:66. [PMID: 31879803 DOI: 10.1007/s10661-019-7966-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 11/08/2019] [Indexed: 06/10/2023]
Abstract
The potential of diffusive gradient in thin film (DGT) as a long-term monitoring tool to assess trace level mercury (Hg) in surface waters was evaluated. A piston type DGT sampler and a plate-type device that could hold 15 DGTs were designed. The device contained piston type DGT samplers with varying diffusive gel thicknesses, that is, 0.5, 0.75, and 1.0 mm, respectively. Three DGT devices were deployed in a lake for 5 weeks, and two were deployed in a stream for 3 weeks. In the lake, the total Hg (THg) mass accumulated in the DGT varied between 0.05 and 0.15 ng, which increased with an increase in deployment time and decreased with an increase in agarose diffusion gel thickness. The DGT concentration in the lake water for a 2 week period was estimated to be about 0.8-1.0 ng/L, which was close to the measured value of 1.1 (± 0.13) ng/L, using the grab sampling technique. However, the DGT estimated at 4 and 6 weeks showed a concentration of about 0.5-0.7 ng/L, which is about twice as small as that measured by grab sampling. This underestimation of the THg levels in water appear to be caused by additional thicknesses of the physical diffusive boundary layer (0.15, 0.5, 1.29 mm) and biofilm, outside the DGT filter. The predicted DGT concentration in the upper stream of the Nakdong River was estimated to be about 0.8-1.4 ng/L, which is similar to the value of 1.22 (± 0.29) ng/L measured in the field by grab sampling. The concentration of THg was estimated to be about 1.0-1.2 ng/L, which is similar to the values measured by grab sampling. The additional diffusion thickness formed outside the DGT filter was 0.018 mm and 0.093 mm at 1 and 3 weeks, respectively, which is not larger than the diffusion gel thickness (0.5-1.0 mm). This was because DGT was installed in a region where the flow velocity is high, and the thickness of the diffusion boundary layer outside the filter is negligible.
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Affiliation(s)
- Seam Noh
- Chemicals Research Division, National Institute of Environmental Research, 22689, Incheon, Republic of Korea
| | - Young-Hee Kim
- Chemicals Research Division, National Institute of Environmental Research, 22689, Incheon, Republic of Korea
| | - Hyuk Kim
- Chemicals Research Division, National Institute of Environmental Research, 22689, Incheon, Republic of Korea
| | - Kwang-Seol Seok
- Chemicals Research Division, National Institute of Environmental Research, 22689, Incheon, Republic of Korea
| | - Minho Park
- Department of Environmental Engineering, Korea University Sejong Campus, 30019, Sejong, Republic of Korea
| | - Mark Xavier Bailon
- Department of Environmental Engineering, Korea University Sejong Campus, 30019, Sejong, Republic of Korea
| | - Yongseok Hong
- Department of Environmental Engineering, Korea University Sejong Campus, 30019, Sejong, Republic of Korea.
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Huang J, Franklin H, Teasdale PR, Burford MA, Kankanamge NR, Bennett WW, Welsh DT. Comparison of DET, DGT and conventional porewater extractions for determining nutrient profiles and cycling in stream sediments. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2019; 21:2128-2140. [PMID: 31681920 DOI: 10.1039/c9em00312f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Determining inorganic nutrient profiles to support understanding of nitrogen transformations in stream sediments is challenging, due to nitrification and denitrification being confined to particular conditions in potentially heterogeneous sediment influenced by benthic microalgae, rooted aquatic plants and/or diel light cycles. The diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques allow in situ determination of porewater concentration profiles, and distributions for some solutes. In this study, DGT, DET and conventional porewater extraction (sectioning and centrifugation) methods were compared for ammonium and nitrate in stream sediments under light and dark conditions. Two-dimensional distributions of Fe(ii) and PO4-P were also provided to indicate the degree of spatial and temporal heterogeneity in sediment porewater, which can explain the sources and sinks of ammonium at various depths in the sediments. Although the conventional porewater extraction method consistently measured higher NH4-N concentrations than the DGT and DET techniques, the study showed that the DET measurements were the most reliable indicator of porewater NH4-N concentrations, with the DGT data being usefully supplementary. However, a large proportion of the NO3-N concentrations measured by DGT and DET were close to or below the method detection limits. Therefore, further development of these techniques is required to reduce the blanks and detection limits to allow natural low sediment porewater NO3-N concentrations to be accurately monitored using DGT and DET. The study indicated that benthic microalgae had direct and indirect influences on porewater nutrient distributions over light-dark cycles. Overall, DGT and DET techniques can be useful for monitoring porewater nutrient concentrations and profiles and for determining how biological processes drive changes in sediment nutrient concentrations and distributions.
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Affiliation(s)
- Jianyin Huang
- Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, SA 5095, Australia.
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Tao Y, Dan D, Xuejiao H, Changda H, Guo F, Fengchang W. Characterization of phosphorus accumulation and release using diffusive gradients in thin films (DGT) - linking the watershed to Taihu Lake, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 673:347-356. [PMID: 30991324 DOI: 10.1016/j.scitotenv.2019.04.102] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 04/05/2019] [Accepted: 04/08/2019] [Indexed: 06/09/2023]
Abstract
Taihu Lake is well known internationally due to its algae bloom, and phosphorus fertilization and accumulation in the watershed soil played an important role in the lake eutrophication. To explore the linkage between soil and sediment legacy P, the soils from four representative land uses in the upstream watershed and sediments from typical lake areas were sampled and analyzed for P species. Meanwhile, the DGT technology was used to characterize the labile P in the soil and sediment and its release dynamics. The results indicated that Taihu Lake was the major total phosphorus sink (TP = 481.7 ± 97 mg/kg) and wheat land the major reactive phosphorus stock (RP = 37.3 ± 9 mg/kg) in the watershed. The DGT-P dynamic with the deployment time (t) presented a downward exponential curve (f(t) = a × t-b, b > 0) and the regression parameters implied the initial P stock (a) and release rate (b) of labile P. Although the result of the extract based method was statistically correlated to the DGT measured P (p < 0.05), the DGT result had advantages over the traditional method due to its in-situ measurement and kinetic characterization of available P. Since the regression parameters reflected combined factors that impact the interaction between solid and solution P, the soil or sediment properties such as pH and organic matters need to be further studied in details, although they presented a significant correlation with DGT-P in this work. Our work provides a new insight in the rapid assessment of the size and resupply capacity of the existing legacy P stocks.
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Affiliation(s)
- Yu Tao
- College of Environmental Science and Technology, Yangzhou University, Yangzhou 225217, China.
| | - Dai Dan
- College of Water Sciences, Beijing Normal University, Beijing 100875, China; State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Han Xuejiao
- State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - He Changda
- College of Environmental Science and Technology, Yangzhou University, Yangzhou 225217, China
| | - Fu Guo
- State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Wu Fengchang
- State Key Laboratory of Environment Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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15
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Time weighted average concentrations measured with Diffusive Gradients in Thin films (DGT). Anal Chim Acta 2019; 1060:114-124. [DOI: 10.1016/j.aca.2019.01.056] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/04/2019] [Accepted: 01/31/2019] [Indexed: 11/22/2022]
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16
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Xu J, Jin G, Tang H, Zhang P, Wang S, Wang YG, Li L. Assessing temporal variations of Ammonia Nitrogen concentrations and loads in the Huaihe River Basin in relation to policies on pollution source control. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 642:1386-1395. [PMID: 30045519 DOI: 10.1016/j.scitotenv.2018.05.395] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 05/28/2018] [Accepted: 05/31/2018] [Indexed: 06/08/2023]
Abstract
To assess the quality of a water environment, an in-depth analysis of temporal patterns of contaminant concentrations in water body should be carried out based on unbiased water quality datasets. In this study, we developed a modified log-linear model to account for non-stationary seasonal variations of contaminant concentrations over multiple periods. The model was applied to analyze temporal changes of the Ammonia Nitrogen (AN) concentration at Middle Reaches of Huaihe River (MRHR) and two major tributaries, Shaying River (SR) and Guo River (GR). The modified model outperformed the original models and fitted the data well with Pearson correlation coefficients ranging from 0.67 to 0.86. Temporal patterns of AN concentrations, loads and sources were identified from 1998 to 2015 in connection to the implementation of Five-Year Plans (FYPs, policies for controlling water pollution) in the Huaihe River Basin (HRB). The results show that the AN concentration experienced a significant decrease. Since FYPs focused on controlling AN point sources, the proportion of AN loads derived from point sources decreased from 48-86% to 1-17% in the MRHR and from 66-92% to 2-56% in the SR and GR. However, rebounds of AN concentration occurred in the first year of each FYP period possibly due to discontinuity of the policy implementation over the transition between two consecutive FYPs. High AN concentration anomalies were found in flood seasons, related to pollution discharge beyond limits and/or irrational regulation of sluices. These results have implications for future pollution control policies in the HRB, particularly, the need to reduce the upper limits of contaminant loads for flood seasons, continuity of the policies implementation, reduction of non-point source pollution, rational sluice regulation and integrated pollution prevention programs. The developed model and approach are applicable to other polluted river basins to facilitate water quality assessment and evaluation of pollution control policies.
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Affiliation(s)
- Jing Xu
- State Key Laboratory of Hydrology-Water Resource and Hydraulic Engineering, Hohai University, Nanjing, China; Centre for Eco-Environmental Modelling, College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, China; School of Mathematical Sciences, Queensland University of Technology, Queensland, Australia.
| | - Guangqiu Jin
- State Key Laboratory of Hydrology-Water Resource and Hydraulic Engineering, Hohai University, Nanjing, China; Centre for Eco-Environmental Modelling, College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, China.
| | - Hongwu Tang
- State Key Laboratory of Hydrology-Water Resource and Hydraulic Engineering, Hohai University, Nanjing, China; Centre for Eco-Environmental Modelling, College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, China.
| | - Pei Zhang
- State Key Laboratory of Hydrology-Water Resource and Hydraulic Engineering, Hohai University, Nanjing, China; Centre for Eco-Environmental Modelling, College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing, China.
| | - Shen Wang
- Melbourne School of Engineering, University of Melbourne, Victoria, Australia.
| | - You-Gan Wang
- School of Mathematical Sciences, Queensland University of Technology, Queensland, Australia.
| | - Ling Li
- School of Civil Engineering, University of Queensland, Queensland, Australia.
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17
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Guan DX, Li YQ, Yu NY, Yu GH, Wei S, Zhang H, Davison W, Cui XY, Ma LQ, Luo J. In situ measurement of perfluoroalkyl substances in aquatic systems using diffusive gradients in thin-films technique. WATER RESEARCH 2018; 144:162-171. [PMID: 30025267 DOI: 10.1016/j.watres.2018.07.031] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 06/21/2018] [Accepted: 07/13/2018] [Indexed: 06/08/2023]
Abstract
To better understand the environmental impact of ubiquitous perfluoroalkyl substances (PFASs) in waters, reliable and robust measurement techniques are needed. As one of the most widely used passive sampling approaches, diffusive gradients in thin-films (DGT) is not only easy to handle but also provides time-weighted analyte concentrations. Based on DGT with XAD18 as a binding agent, we developed a new methodology to measure two frequently detected PFASs in surface waters and wastewaters, i.e. perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Their diffusion coefficients in the diffusive gel, measured using an independent diffusion cell, were 4.37 × 10-6 and 5.08 × 10-6 cm2 s-1 at 25 °C, respectively. DGT had a high capacity for PFOA and PFOS at 196 and 246 μg per gel disk, suggesting the DGT sampler was suitable for deployment of several weeks. Time-integrated concentrations of PFOA and PFOS in a natural lake and river, and a municipal wastewater treatment plant effluent using DGT samplers deployed in situ for 12-33 d were comparable to those measured by a solid-phase extraction method coupled with high-frequency grab sampling. This study demonstrates that DGT is an effective tool for in situ monitoring of PFASs in natural waters and wastewaters.
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Affiliation(s)
- Dong-Xing Guan
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, PR China
| | - Ya-Qing Li
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, PR China; National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, PR China
| | - Nan-Yang Yu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, PR China
| | - Guang-Hui Yu
- National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, Jiangsu, 210095, PR China
| | - Si Wei
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, PR China
| | - Hao Zhang
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, United Kingdom
| | - William Davison
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, United Kingdom
| | - Xin-Yi Cui
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, PR China
| | - Lena Q Ma
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, PR China; Soil and Water Science Department, University of Florida, Gainesville, FL, 32611, United States
| | - Jun Luo
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu, 210023, PR China.
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18
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Li T, Panther J, Qiu Y, Liu C, Huang J, Wu Y, Wong PK, An T, Zhang S, Zhao H. Gas-Permeable Membrane-Based Conductivity Probe Capable of In Situ Real-Time Monitoring of Ammonia in Aquatic Environments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:13265-13273. [PMID: 29067813 DOI: 10.1021/acs.est.7b03552] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Aquatic ammonia has toxic effects on aquatic life. This work reports a gas-permeable membrane-based conductivity probe (GPMCP) developed for real-time monitoring of ammonia in aquatic environments. The GPMCP innovatively combines a gas-permeable membrane with a boric acid receiving phase to selectively extract ammonia from samples and form ammonium at the inner membrane interface. The rate of the receiving phase conductivity increase is directly proportional to the instantaneous ammonia concentration in the sample, which can be rapidly and sensitively determined by the embedded conductivity detector. A precalibration strategy was developed to eliminate the need for an ongoing calibration. The analytical principle and GPMCP performance were systematically validated. The laboratory results showed that ammonia concentrations ranging from 2 to 50 000 μg L-1 can be detected. The field deployment results demonstrated the GPMCP's ability to obtain high-resolution continuous ammonia concentration profiles and the absolute average ammonia concentration over a prolonged deployment period. By inputting the temperature and pH data, the ammonium concentration can be simultaneously derived from the corresponding ammonia concentration. The GPMCP embeds a sophisticated analytical principle with the inherent advantages of high selectivity, sensitivity, and accuracy, and it can be used as an effective tool for long-term, large-scale, aquatic-environment assessments.
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Affiliation(s)
- Tianling Li
- Centre for Clean Environment and Energy, Gold Coast Campus, Griffith University , Southport, QLD 4222, Australia
| | - Jared Panther
- Centre for Clean Environment and Energy, Gold Coast Campus, Griffith University , Southport, QLD 4222, Australia
- Goulburn-Murray Water , Tatura, VIC 3616, Australia
| | - Yuan Qiu
- Centre for Clean Environment and Energy, Gold Coast Campus, Griffith University , Southport, QLD 4222, Australia
- Guangxi Vocational and Technical Institute of Industry , 37 Xiuling Road, Nanning, Guangxi 530005, China
| | - Chang Liu
- Centre for Clean Environment and Energy, Gold Coast Campus, Griffith University , Southport, QLD 4222, Australia
- Department of Chemistry, Liaoning Medical University , 40 Songpo Road, Jinzhou, Liaoning 121001, China
| | - Jianyin Huang
- Centre for Clean Environment and Energy, Gold Coast Campus, Griffith University , Southport, QLD 4222, Australia
- Division of Information Technology, Engineering and Environment, School of Natural and Built Environment, Mason Lakes Campus, University of South Australia , Adelaide, SA 5095, Australia
| | - Yonghong Wu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences , 71 East Beijing Road, Nanjing, Jiangsu 210008, China
| | - Po Keung Wong
- School of Life Sciences, The Chinese University of Hong Kong , Shatin, NT, Hong Kong SAR, China
| | - Taicheng An
- Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering, Guangdong University of Technology , Guangzhou, 510006, China
| | - Shanqing Zhang
- Centre for Clean Environment and Energy, Gold Coast Campus, Griffith University , Southport, QLD 4222, Australia
| | - Huijun Zhao
- Centre for Clean Environment and Energy, Gold Coast Campus, Griffith University , Southport, QLD 4222, Australia
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19
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A modified DGT technique for the simultaneous measurement of dissolved inorganic nitrogen and phosphorus in freshwaters. Anal Chim Acta 2017; 988:17-26. [DOI: 10.1016/j.aca.2017.08.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 07/20/2017] [Accepted: 08/16/2017] [Indexed: 11/18/2022]
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