丹江鹦鹉沟小流域氮素随径流的迁移及对水质的影响

摘要

计算小流域非点源氮素流失负荷，并以此开展丹江水源区水体污染源解析和控制研究。基于流域断面及小区监测试验，利用平均浓度法对鹦鹉沟流域氮素年均流失模数和不同土地利用类型的非点源污染负荷进行计算分析。结果表明：径流水质中主要是总氮质量浓度超标，且硝氮质量浓度均大于氨氮质量浓度；当坡耕地坡度大于25°时，氮素流失严重，水质极差；农村生产生活污染物排放对水质有很大影响，从断面1到把口站，硝氮质量浓度和总氮质量浓度增加较大；农地、草地和林地的总氮年均径流流失模数分别为0．36、0．22和0．09 t/（a·km2）；流域出口非点源污染物氨氮、硝氮和总氮的平均质量浓度分别为0．17，4．71和7．55 mg/L，点源污染物氨氮、硝氮和总氮的平均质量浓度分别为0．20、2．12和4．08 mg/L。总体来说，鹦鹉沟流域径流中总氮的流失模数为0．89 t/（a·km2），总氮是影响水质的主要污染物，需加强对坡耕地氮素流失和农村生活垃圾的治理。%Nitrogen loss load of non-point source in small watershed was calculated and analysis and control research of water pollution sources in Danjiangkou were carried out.Based on the monitoring of watershed section and runoff plots,the average annual nitrogen loss modulus and non-point source pollution nitrogen load of different land use types were calculated using mean concentration method in Yingwugou watershed.The results showed that the total nitrogen content was the major exceeded pollutant in runoff and nitrate nitrogen content was always greater than the ammonia content.When the slope of sloping cropland was greater than 25°,severe nitrogen loss and poor water quality happened. The rural production and living pollutant emissions had a great impact on water quality.Nitrate nitrogen concentration and total nitrogen concentration both increased greatly from watershed section 1 to mouth station.The average annual total nitrogen loss modulus of farmland,grassland and forestland were 0.36,0.22 and 0.09 t/(a·km2 ),respectively.The average non-point source pollutant concentration of ammonia nitrogen,nitrate nitrogen and total nitrogen in watershed export were 0.17,4.71 and 7.55 mg/L,respectively.The average point source pollutant concentration of ammonia nitrogen,nitrate nitrogen and total nitrogen in watershed export were 0.20,2.12 and 4.08 mg / L,respectively.The average total nitrogen runoff loss modulus in Yingwugou watershed was 0.89 t/(a· km2 ).The total nitrogen is the major pollutant affecting water quality.The nitrogen loss of sloping farmland and rural garbage must be controlled effectively.