DGT induced fluxes in sediments model for the simulation of phosphorus process and the assessment of phosphorus release risk.

Diffusive gradients in thin films (DGT)-induced flux in sediments (DIFS) (DGT-DIFS) model for phosphorus (P) has been investigated to provide a numerical simulation of a dynamic system of the DGT-pore water-sediment in Dianchi Lake (China). Kinetic parameter-T C (33-56,060 s), distribution coefficient-K d (134.7-1536 cm(3)g(-1)), and resupply parameter-R (0.189-0.743) are derived by DGT measurement, the sediment/pore water test, and the DIFS model. The changes of dissolved concentration in DGT diffusive layer and pore water and sorbed concentration in sediment, as well as the ratio of C DGT and the initial concentration in pore water (R) and mass accumulated by DGT resin (M) at the DGT-pore water-sediment interface (distance) of nine sampling sites during DGT deployment time (t) are derived through the DIFS simulation. Based on parameter and curves derived by the DIFS model, the P release-transfer character and mechanism in sediment microzone were revealed. Moreover, the DGT-DIFS parameters (R, T C , K -1 , C DGT ), sediment P pool, sediment properties (Al and Ca), and soluble reactive P (SRP) in overlying water can be used to assess "P eutrophication level" at different sampling sites with different types of "external P loading." The DGT-DIFS model is a reliable tool to reveal the dynamic P release in sediment microzone and assess "internal P loading" in the plateau lake Dianchi.