This book focuses on the development of DGT (diffusive gradients in thin films) and the related techniques for measuring and investigating the geochemical process and P transfer across the sediment/water or sediment/root interface in lakes. A series of DGT techniques such as new types of probes, test methods in sediment or the rhizosphere, DIFS (DGT induced fluxes in sediments and soils) model for kinetic P exchange, CID (computer imaging densitometry) for S(-II), and microchelex gel/LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) have been developed.

The corresponding chapters on the theory and methodology of DGT, the "internal P loading" or P transfer across sediment/root in two lakes, provide insights into the research method and conclusions, including the P release mechanism, the quantification of "internal P loading", kinetic P exchange in DGT/sediment interface, Fe- or S(-II)-microniches at submillimeter scales in sediments for the prediction ofP release, and DGT as a surrogate for the prediction of P uptake by roots.

It also offers new perspectives in the fields of P analysis and P process in micro-interfaces in lakes using DGT techniques. The P remobilization from Fe-bound P, the coupled Fe-S(-II)-P geochemical reaction and algae biomass breakdown causing P release, are elucidated using DGT methods in sediment layers. DGT parameters and curves for time or distance derived from DIFS can be used to assess kinetic P release in the sediment microzone. CID and LA-ICP-MS methods deliver Fe- and S(-II) images at submillimeter scales, which can be used for the quantification of flux related to microniche peaks and the prediction of P release from Fe-microniche or Fe-S(-II)-P geochemical reactions. DGT measurements in-situ in rhizosphere or rhizonbox can give CE (effective concentration) and CDGT values for the prediction of P accumulated in plant tissues.

This book provides a valuable reference resource for senior graduate students, lecturers and researchers in the fields of the geochemical process of eutrophic elements in lakes, lake eutrophication mechanism and environmental analysis.

Inhalt

Section 1: The basic theory and methodology.- The theory of P process at sediment/water interface (SWI).- Problem introduction and studying zones.- The research methodology.- Section 2: Internal P-loading at SWI of Dianchi lake.- The internal P-loading at SWI of Dianchi lake assessed by DGT technique.- The coupled Fe-S-P biogeochemical process for P release and sulfide microniche in sediments assessed by DGT-CID technique.- The P release risk predicted by chemical image of Fe in sediment porewater measured by DGT/LA-ICP-MS and Fe-microniches.- Section 3: The P behavior at the interface of sediment/the rhizosphere of aquatic plants in Erhai lake.- The uptake and accumulation mechanisms of P predicted by in-situ DGT test at the rhizosphere of aquatic plants in Erhai lake.- The uptake and accumulation mechanisms of P assessed by DGT/rhizonbox method.- Conclusion and Prospect.