巢湖水及沉积物中总磷的分布变化特征

磷是导致巢湖水体富营养化的主要营养物质。采集大量巢湖表层水和沉积物样品,通过检测上覆水和沉积物中总磷含量,分析巢湖水体中磷的时空变化及赋存特征。结果显示:巢湖南淝河和裕溪河河口的上覆水中总磷含量值时间变化特征为8月5月3月12月;且南淝河口总磷含量年均值超过地表水Ⅴ类水质标准,明显高于裕溪河口值;表层水和沉积物中总磷含量在空间分布上呈西高东低趋势,最高值均出现在靠近合肥市河口处。巢湖周边土壤及湖区磷的等值线分布表明:杭埠河流域农业污染、东巢湖东南部水土流失可能是巢湖磷面源污染的主要来源。巢湖上覆水和沉积物中总磷的相关系数为0.515,蓝藻爆发期全湖表层沉积物中总磷含量显著减少,揭示目前内源磷释放已是巢湖富营养化的主要因素。结果将对巢湖流域的污染综合防治及蓝藻治理工作提供科学依据。

SPATIAL AND TEMPORAL VARIATION OF PHOSPHORUS IN WATER AND SEDIMENT FROM CHAOHU LAKE

Phosphorus is the main nutrients to eutrophication in the Chaohu Lake, the study on the content and spatial distribution of phosphorus in sediments can help to guide eutrophication reduction of the Lake. A large number of water and sediment samples were collected from entire lake including its main river entrances. The temporal and spatial variation of total phosphorus and its occurrence characteristics in the Chaohu Lake were investigated. The results showed that the seasonal change trend of total phosphorus contents in Nanfei River and Yuxi River entrances presented a pattern of August May March December. The annual average of total phosphorus content was more than Grade Ⅴ in the Nanfei River entrance, significantly higher than that of the Yuxi River entrance. The spatial distribution indicated that total phosphorus contents in surface water and sediment had a similar trend, the patches of highest contents confined in the entrances near the Hefei City, while there was no significant river input in the eastern lake. Spatial characteristics of total phosphorus in the topsoil (mg·kg^-1) of Chaohu Lake and its watershed showed agricultural pollution in the Hangbu river basin and surface runoff in southeastern lake might be the primary nonpoint phosphorus pollution. The correlation coefficient of total phosphorus between surface water and sediment was 0.515, and the total phosphorus contents in surface sediment were significantly decreased during the algal bloom period, suggesting that endogenous phosphorus cycle was key to Chaohu Lake eutrophication. Our results can provide scientific basis for the comprehensive treatment of the pollution in the Chaohu River Basin and the control of blue algae.