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 *C E * (effective concentration) and C DGT 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.

Introduces DGT (diffusive gradients in thin films) and related techniques to solve the relative problems of P-release and -transfer across sediment/water interface and sediment/root interface Provides formulas and equations Presents the DGT technique in two lakes (Dianchi and Erhai lakes) in southwest of China Includes supplementary material: sn.pub/extras

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.