Element remobilization, “internal P-loading,” and sediment-P reactivity researched by DGT (diffusive gradients in thin films) technique
2015
Wu, Zhihao | Wang, Shengrui | He, Mengchang | Zhang, Li | Jiao, Lixin
Labile P, Fe, and sulfide with the high spatial resolution in sediment porewater of five sites (A–E) of Dianchi Lake (China) were measured at same locations using AgI/Chelex-100, Chelex-100, and ferrihydrite DGT (diffusive gradients in thin films) probes. DGT derived P/Fe/S concentrations in sediment porewater on millimeter or sub-millimeter scale in order to reveal the element remobilization process and the mechanism of “internal P-loading” of sediments in Dianchi Lake. Decomposition of alga biomass in the uppermost sediment layer and the reductive dissolution of Fe-bound P in the anoxic sediment were the two main processes causing P release. A dynamic numerical model-DIFS (DGT-induced flux in sediments) was used to assess sediment-P reactivity (capacity of solid pool and rate of transfer) and P release risk by kinetic parameter—T C (1089∼20,450 s), distribution coefficient—K d (167.09∼502.0 cm³ g⁻¹), resupply parameter—R (from 0.242 to 0.518), and changes of dissolved/sorbed concentration, R and M at the microzone of DGT/porewater/sediment.
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