长兴县北部地区的土地利用与水质响应研究

以长兴县北部地区为例,以氨氮作为污染评价指标,分别利用改进后的输出系数法和研究区社会污染普查资料合理估算了研究区全流域和各乡镇的非点源污染量及点源污染排放量。通过对比污染输出总量和国家地表水环境质量标准发现,研究区全流域整体达到二级水质标准,但夹浦镇水质严重超标,且主要贡献来自于点源污染,其余乡镇水质良好。进一步分析发现,长兴县北部地区不同的土地利用组合类型和比例对非点源污染输出有着重要影响,总体规律是耕地对非点源污染输出贡献比例最大,其次是居民地和裸地,并且随着林地比例的增加和耕地、居民地的减少,污染逐渐降低。

Land Use and Water Quality Response in the Northern Region of Changxing County

Taking the northern region of Changxing County as example,with ammonia nitrogen as pollution assessment index,an improved export coefficient method was used for estimating polluting load of non-point source pollution and the social pollution census data in the study area to estimate point source pollution.By comparing the total pollution output and the national surface water environmental quality standards,it was found that the whole study area achieves the second water quality standard,however,Jiapu Township exceeds the water quality standards seriously because of the superfluous point source pollution.The water quality of other townships is good.Further analysis showed that different types of land use and proportion in the northern region of Changxing County have a significant impact on the non-point source pollution,the general law is cultivated land contributed the largest share of the non-point source pollution output,followed by residents and bare land,besides,with the increase in the proportion of forest and the decrease of farmland and residential,the non-point source pollution reduces gradually.