湘江干流衡阳段水质变化

Water quality variation of Hengyang section of Xiangjiang River

为研究湘江衡阳段水质变化，在湘江衡阳段干流设置7个监测断面，经2001—2005年监测分析表明：湘江衡阳段干流重金属污染逐步减轻，营养型污染有所增加，污染逐渐由上游向下游转移，水质污染都有不同程度减轻，整体水质呈改善趋势。分析总结了水质污染变化原因，指出衡阳市养殖业的发展成为衡阳段有机污染的重要来源之一，城镇人口增加是营养型污染增加的主要原因。

Seven monitoring sections located in the main stream of the Hengyang section of the Xiangjiang River were used to investigate water quality variation. The results from 2001 to 2005 show that the water was polluted by fewer heavy metals but more nutrients; the main polluted region shifted from the upper reaches to the lower reaches; and the water pollution in different reaches was more or less alleviated, indicating the improvement of water quality in the whole stream. Analyses of the water quality variation show that aquiculture is a main source of organic pollution, and the growth of the urban population is the main reason for nutrient pollution.