环境地球化学国家重点实验室知识库

The effects of temperature on phosphorus (P) release in sediments of Hongfeng Lake, southwest China, were investigated under simulation condition. The distributions of labile P in sediments were measured in situ using a diffusive gradients in thin-films (DGT) technique (Zr-oxide DGT) at a two-dimensional, sub-millimeter spatial resolution. The changes of P fractions in sediments at different temperatures were also investigated using a chemical fractionation technique which divided sediment P into NH4Cl-P, BD-P, NaOH-P, HCl-P, and Residual P. The results showed that the concentrations of labile P in sediments increased rapidly as the simulating temperature increased, reflecting a rapid P release from sediments. The NaOH-P concentrations in sediments showed the greatest decrease (accounting for 79.3 % of total decrease) during the experiment, suggesting that the increase of labile P in sediments was mainly due to the transformation of NaOH-P. The release of HCl-P also occurred in sediments, increasing the labile P concentration in pore waters. The seasonal variation of temperature and its induced biological-chemical changes at the sediment-water interface (such as organic matter degradation, and respiration) might be an important factor affecting the P release in sediments of Hongfeng Lake. Our results provide new information for illuminating P biogeochemical cycling processes at the interface in eutrophic lakes.