文摘
One combined AgI/Chelex-100 DGT probe and the other ferrihydrite DGT probe were arranged back–to-back at the same location of the sediment/water interface (SWI) of trophic Dianchi Lake for the simultaneous determination of soluble reactive phosphorus (SRP), metals and sulfide with the high spatial resolutions. DGT-computer imaging densitometry (CID) technique was used for grayscale analysis of AgI gel in sediments. The character of DGT profiles of metals indicated the geochemical processes such as the reductive dissolution of Fe and Mn oxides and the release of trace metals adsorbed on them. SRP DGT profile and upward diffusive flux across SWI indicated the breakdown of alga biomass in the uppermost surface sediment, the reductive dissolution of Fe–P in deeper surface sediment and the distinct “internal P loading” character of sediment of Dianchi Lake. Metal–sulfide solubility was assessed by saturation index (SI). Based on DGT-CID technique, the sulfate reduction and microniche character in anoxic sediment were verified and assessed.