林芝市农业面源污染负荷时空变化与分布特征

为分析西藏林芝地区的农业面源污染形势与特征,基于林芝市2000—2015年的农业统计资料,应用输出系数模型估算了该地区农业面源污染总氮(TN)、总磷(TP)年输出负荷。并对农村生活污水、农田化肥、畜禽养殖三类污染源分别进行了分析。结果表明:TN、TP均呈现逐年平稳上升的趋势;农业面源污染高负荷区主要集中在工布江达县、波密县和林芝县,而农业面源污染负荷强度最高的行政区为米林县;农业面源污染负荷的三大营养源贡献中畜禽养殖输出负荷的贡献率随时间的推移有明显增加的趋势,90%的农业面源污染负荷来源于畜禽养殖和农田化肥;林芝市农牧业发达地区农业面源污染形势不容乐观,须大力开展防控工作,以改善该地区农业面源污染日趋严重的状况。

Spatio-temporal changes and distribution characteristics of pollutant loads from agricultural non-point sources in Nyingchi, Tibet

This paper is aimed at analyzing the trends and characteristics of agricultural non-point source pollution in Nyingchi,Tibet.The annual emission loads of total nitrogen (TN) and total phosphorus (TP) from the agricultural non-point source pollution were estimated by applying the export coefficient model to the statistical data of agriculture in Nyingchi from 2000-2015.The agricultural non-point source pollution can be caused by rural domestic sewage,application of chemical fertilizers,and livestock and poultry breeding.TN and TP showed a steady upward trend year by year.The loads of agricultural non-point pollution were higher in the Gongbujiangda,Bomi,and Nyingchi counties,whereas that in the Milin county was the highest.The pollution load of TN and TP owing to livestock and poultry breeding showed a significant increasing trend with time among the three nutrient sources.Overall,90% of the agricultural non-point source pollution load resulted from livestock and poultry breeding and the application of chemical fertilizers.Importantly,the situation of the agricultural non-point source pollution in Nyingchi is not optimistic,especially in the developed areas of agriculture and animal husbandry.It is necessary to carry out prevention and control measures for improving the situation of agricultural non-point source pollution in this district.