HU Xinping^{1, 2}， LI Pangyi³， WANG Jingfu¹， YANG Haiquan¹， GUO Jianyang¹

(1.State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;

2.University of Chinese Academy of Sciences, Beijing 100049, China;

3.School of Environmental Science & Engineering, Huazhong University of Science and Technology, Wuhan 430074, China)

Abstract：Phosphorus pollution in the Wujiangdu Reservoir has been a matter of serious concern, due to the input of phosphorus from Xifeng River. However, the release of phosphorus from the upstream and the influence of damming on the phosphorus pollution in the Wujiangdu Reservoir have little concerned. Based on the analysis of phosphorus and its geochemical forms in surface sediments and sediment cores, the current situation and historical trend of phosphorus in Wujiangdu sediments, as well as its response to river damming, were investigated. The results showed that: 1) the phosphorus pollution in sediments of the Wujiangdu Reservoir was highly serious, which is much more serious than that of other lakes or reservoirs in China; 2) phosphorus contents in sediments of the Wujiangdu Reservoir increased from the upstream to the downstream, mainly caused by the increase in NaOH-P in the sediments; 3) spatial variation of phosphorus in sediments may be caused by the settlement of particles or algae along the flow direction, or by the deposition of phosphorus caused by the oxidation of Fe2+ in water, but the real reason needs further confirmation. This study indicated that sedimentary phosphorus detained in the upper reservoir may be released again, leading to the serious sedimentary pollution of phosphorus in the upper and middle reaches of the Wujiangdu Reservoir.

Key words：phosphorus; sedimentary record; retention effects; Wujiangdu Reservoir; geochemical forms

EARTH AND ENVIRONMENT Vol.50, No.6, Tot No.350, 2022, Page 805