基于DGT技术的黄河上游典型水库沉积物氮磷释放与污染源解析

In order to solve the problem of insufficient analysis of the pollution sources of the reservoir under the river-reservoir connectivity of the upper reaches of the Yellow River, this study analyzed the pollution characteristics and diffusion flux of a typical reservoir in the upper reaches of the Yellow River (Shenjiahe Reservoir) based on the DGT and HR-Peeper technology. The results showed that the water quality at the entrance of the reservoir was inferior to Class V, and the reservoir sediments were under heavy pollution. The average concentration of soluble phosphate (SRP) in the overlying water at each point was lower than that of the pore water, indicating that the SRP of sediment diffused upward due to the concentration gradients. The correlations between DGT-P and DGT-Fe and the concentration difference at the sediment-water interface were spatially heterogeneous. The sediment DGT-P release was dominated by Fe-P reduction release at point 1, the ability of surface sediment DGT-P release was poor at point 2, and surface sediment DGT-P had strong release ability; thus, different governance measures could be taken according to the release mechanisms. The concentrations of NH₄⁺-N decreased and the concentrations of NO₃^--N increased at point 1 (4-8 mm), point 2 (8-20 mm), and point 3 (-8-8 mm) near sediment-water interface. The increase in TP, TN, and NH₄⁺-N loading mainly came from the sediments release, and the impact of external input from the Qingshui River on nitrogen cannot be ignored. These results provide a reference for the analysis of pollution sources and the management of river reservoirs in the upper reaches of the Yellow River.