Bioavailability assessment of phosphorus and metals in soils and sediments: a review of diffusive gradients in thin films (DGT)
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This paper provides an overview of the principle and latest development of the diffusive gradients in thin films (DGT) technology and its applications in environmental studies with a focus on bioavailability assessment of phosphorus and metals in sediments and soils. Compared with conventional methods, DGT, as a passive sampling method, has significant advantages: in situ measurement, time averaged concentrations and high spatial resolution. The in situ measurement avoids artificial influences including contamination of samples and sample treatment which may change the forms of chemicals. The time averaged concentration reflects representative measurement over a period of time. The high-resolution information captures the biogeochemical heterogeneity of elements of interest distributed in microenvironments, such as in the rhizosphere and the vicinity of the sediment-water interface. Moreover, DGT is a dynamic technique which simultaneously considers the diffusion of solutes and their kinetic resupply from the solid phases. All the advantages of DGT significantly promote the collection of “true” information of the bioavailable or labile forms of chemicals in the environment. DGT provides potential for applications in agriculture, environmental monitoring and the mining industry. However, the applications are still at the early testing stage. Further studies are needed to properly interpret the DGT-measured results under complex environmental conditions, and standard procedures and guideline values based on DGT are required to pave the way for its routine applications in environmental monitoring.
KeywordsDiffusive gradients in thin films (DGT) Bioavailability Metals Phosphorus High resolution Binding gels Soil
Dr. Chaosheng Zhang thanks Hong Kong Baptist University for provision of the prestigious University Fellowship, enabling him to visit the university in 2013 as part of his sabbatical leave from the National University of Ireland, Galway. This review was partly sponsored by the Chinese “111” Project (No. B08037) awarded to Sichuan University, China.
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