三峡库区湖北段非点源污染氮磷排放时空分布特征

目的]了解三峡库区湖北段非点源污染情况,找到主要污染源和重点控制区,为该区生态环境的建设和治理提供科学支持。方法]运用输出系数模型结合降雨侵蚀力影响系数和入河系数模拟计算研究区1990,2000,2005和2010年的非点源污染氮磷排放总量、各污染源氮磷污染排放量及贡献率以及各地区氮磷排放的时空分布特征。结果]三峡库区湖北段1990,2000,2005和2010年的TN排放量在2 500t以上、TP排放量在250t以上,2000年达到最高,TN,TP年均排放量分别为3 612.78和393.75t/a,年均排放强度为3.10和0.34kg/(hm~2·a),研究区非点源污染以氮污染为主。水田和旱地是造成氮污染的主要原因,其次是农村人口;水田和旱地也是磷污染排放的主要贡献源,其次是猪的养殖。结论]研究区非点源污染总体呈现两侧高中间低的区域性分布。巴东县为氮磷排放的重点控制区域。

Spatio-temporal Distribution of Pollution Loads from Agricultural Non-point Sources Nitrogen and Phosphorus in Three Gorges Reservoir Area of Hubei Province

Objective] In order to understand the non-point source pollution in Three Gorges Reservoir area of Hubei Province to find the main pollution sources and the key control area.Methods] The non-point source pollutions of nitrogen and phosphorus emissions in 1990, 2000, 2005 and 2010 were calculated with the rainfall erosivity coefficient and simulated by river export coefficient model, the temporal and spatial distribution characteristics of nitrogen and phosphorus emissions of various pollution sources and their contribution rates were analyzed.Results] TN emissions was more than 2 500 t and TP emissions was more than 250 t, and they both got the highest in 2000. The average annual TN emissions were 3 612.78 t/a and TP was 393.75 t/a, the annual TN and TP emission intensity were 3.10, 0.34 kg/(hm²·a). Therefore the study area was mainly nitrogen polluted. Paddy field and dry land were the main causes of nitrogen pollution source, the followed source was rural population. Paddy field and dry land were the main contributions of phosphorus pollution, pig breeding was the next one.Conclusion] The non-point source pollution in the study area had its spatial distribution characterized by its low pollution in both sides and high in the middle part. Badong district was recognized as the key control area of nitrogen and phosphorus emissions.