洞庭湖营养盐赋存及对水沙情势变化响应综述OA北大核心CSTPCD

The nutrient status of Dongting Lake is closely related to the water and sediment conditions.The variations in water-sediment conditions alter the nutrient status of the lake,thereby affecting the ecological security in the middle and lower reaches of the Changjiang River Basin.The variation characteristics of water-sediment and nutrient conditions in Dongting Lake area since the 1950s were summarized and the research progress of the relationship between water-sediment conditions and nutrient condi-tions was reviewed.The results showed that influenced by cutoffs of the lower Jingjiang River,closure of the Gezhouba Dam,opera-tion of the Three Gorges Reservoir,and other factors,the flow diversion and sediment diversion of the three outlets of the Jingjiang River decreased,the sediment deposition in Dongting Lake tended to slow down,and the water level of lake area decreased under the same flow.The nitrogen and phosphorus pollution of water in Dongting Lake has deteriorated in the past 30 a,but the nitrogen and phosphorus pollution of sediment has not deteriorated significantly.The reduction of the flow diversion at the three outlets di-rectly led to the reduction of the water environment capacity,which increased the total nitrogen concentration;the reduction of sed-iment diversion reduced the granular phosphorus content in the lake area,which decreased the total phosphorus concentration and increased the proportion of dissolved phosphorus;the release of nutrient from the siltation of Dongting Lake was an important factor affecting the nitrogen and phosphorus content of the water in the lake area;the alternation of wet and dry conditions on the conti-nental beaches and the change of aquatic plant communities caused by the change of the water level in the lake area promoted the accumulation of nitrogen and phosphorus in the sediment and overlying water.This paper can provide theoretical support for the follow-up study of the coupling relationship between water sediment and the water environment and provide references for the regulation of water and sediment for improving the water environment of Dongting Lake.