太湖地区农业源对水体氮污染的贡献——以宜溧河流域为例

宜溧河流域是太湖上游的主要集水流域,该流域的污染物排放是太湖污染负荷的重要来源。重点针对种植业、畜禽养殖业和水产养殖业三种农业污染源,基于统计年鉴、遥感解译、野外监测和调研等多种手段,对种植业、水产养殖业和禽畜养殖业分行业进行了氮污染负荷核算。结果表明,2013年宜溧河流域主要农业源氮污染负荷总量为6861 t,单位排放强度为22.2 kg·hm^-2;种植业和禽畜养殖业是宜溧河流域氮污染的主要来源,其中种植业源TN排放量最大,为3832 t,占总负荷的55.9%,种植业中蔬菜地对氮污染的贡献较大,TN排放量占总农业源负荷的18.7%;禽畜养殖业源TN排放量次之,占总负荷的34.4%;水产养殖业源TN排放量最小,占总负荷的9.8%.因此,针对宜溧河流域农业源氮污染的治理,在考虑禽畜养殖和水产养殖的同时,应以种植业污染尤其是菜地作为重点研究对象,制定合理的控制措施。

Estimating Contribution of Agricultural Sources to Aquatic Nitrogen Load in Taihu Lake Region:A Case Study of Yili River Catchment

Taihu Lake region is densely populated, along with developed industry and intensive agriculture. The surface water pollution, especially eutrophication, has seriously affected both water supply and economic development in this region in recent years. Nitrogen(N) is a major pollutant in the surface water in this region. The Yili River catchment is a main upper catchment of the Taihu Lake. Hence, identifying the sources of N loads would help manage N fertilizers and water resources and reduce surface water pollution effectively. In this study, three main sources of agricultural source pollution including cropland, livestock and poultry husbandry, and aquaculture were analyzed through survey, monitoring, remote sensing, and use of statistical data and GIS technologies. Results showed that the total N load in this catchment was 6861 t in 2013, with an average of 22.2 kg·hm^-2. Cropland, livestock and poultry husbandry were the main sources of N pollution in this catchment, which was 3832 t and 2358 t, accounting for 56% and 34% of the total agricultural N loads, respectively. The N load from aquaculture was only 9.8% of the total agricultural N loads.Vegetable land was one of the major N pollution sources of cropland, amounting to 18.7% of the total agricultural N. Therefore, policies and managements of water N pollution control should be focused on vegetable systems in this area.