湖泊底泥氮、磷污染分布特征及风险分析——以钟祥市南湖为例
Distribution Characteristics and Risk Analysis of Nitrogen Phosphorus Pollution in Lake Sediments—Case of Nanhu Lake in Zhongxiang City

以汉江中下游典型湖泊钟祥市南湖为研究区，对湖泊底泥进行分层采样并测定各分层氮磷含量，摸清湖泊氮磷污染分布规律，同时进行底泥氮磷静态释放试验，综合分析底泥氮磷污染程度及对湖泊水环境的影响。结果表明：1) 湖泊各检测点位底泥营养盐污染严重：总氮各层平均值在1224 mg/kg~1473 mg/kg之间；总磷各层平均值在702 mg/kg~939mg/kg之间；有机质各层平均值在20.3 mg/kg~27.7 mg/kg之间，大部分底泥氮磷为中重度污染。2) 不同深度的底泥均可向上覆湖水释放氮，释放速度在18.75 mg/(m²？d)~303.1 mg/(m²？d)之间；总磷释放速度有正有负，在？18.5 mg/(m²？d)~11.61 mg/(m²？d)之间，这表明了湖泊底泥不仅不会向水体释放磷，还可反向吸附孔隙水中磷，有利于湖泊水体富营养化控制。
Taking Nanhu Lake in Zhongxiang City, a typical lake in the middle and lower reaches of the Han River, as the research area, stratified sampling was conducted on the sediment of the lake, and the nitrogen and phosphorus content in each layer was measured to understand the distribution pat-tern of nitrogen and phosphorus pollution in the lake. At the same time, static nitrogen and phos-phorus release experiments were conducted on the sediment to comprehensively analyze the de-gree of nitrogen and phosphorus pollution in the sediment and its impact on the water environment of the lake. The results indicate that: 1) the sediment nutrient pollution at each detection point in the lake is severe: the average value of total nitrogen in each layer ranges from 1224mg/kg to 1473 mg/kg; The average value of total phosphorus in each layer ranges from 702 mg/kg to 939 mg/kg; The average value of organic matter in each layer ranges from 20.3 mg/kg to 27.7 mg/kg, and most of the sediment nitrogen and phosphorus are moderately or severely polluted. 2) Different depths of sediment can release nitrogen into the overlying lake water, with a release rate ranging from 18.75 mg/(m²？d) to 303.1 mg/(m²？d); The release rate of total phosphorus varies from positive to negative, ranging from ？18.5 mg/(m²？d) to 11.61 mg/(m²？d). This indicates that lake sediment not only releases phosphorus into the water body but also reversely adsorbs phosphorus in pore water, which is beneficial for eutrophication control of lake water bodies.