海岛非点源污染负荷估算方法研究

Study on estimation method of non-point source pollution load on Island

基于流域单元思想,提出一种非点源污染负荷估算方法:借助GIS提取模拟河网,识别流域边界,并划分汇水区和子流域,为流域非点源污染的估算提供基础的数据平台.在此基础上,与土地利用专题图叠加,计算各子流域内不同土地利用类型的面积,构建非点源负荷系统,利用各污染排放系数和入海系数,结合多年的降雨量,并引入坡度因子作为限制条件,估算污染负荷总量.结果显示,南长山岛非点源全氮、全磷年负荷量分别为11539kg和2025kg.氮污染中,各污染源强的贡献率依次为居民生活>大气沉降>土地利用>畜禽养殖;磷污染中,各污染源强的贡献率依次为居民生活>土地利用>大气沉降>畜禽养殖.基于此,探讨海岛地区非点源污染排放特征及对水环境质量影响,可为海岛地区污染物总量调控和环境健康发展提供一种技术方法.

An estimation method of non-point source（NPS） pollution load based on watershed unit ideas was discussed in this study. Firstly, extracting the river network data, identifying the watershed boundaries, anddividing the catchment and sub basin using GIS were finished. And then, the data from first step weresuperposed with the thematic maps of land use and used to calculate the area of different land use types in each sub basin. Third, the NPS pollutant load system was constructed using the emissionfactor, the coefficient of the sea and years of rainfall. Also, the slope factor was introduced as the limiting condition. At last, the total amount of pollution load was estimated. The results indicated that the total nitrogen（TN） and total phosphorus（TP） loads of Nanchangshan Island from NPS were respectively 11539 kg and 2025 kg. For TN loads, the magnitude order of the contribution of NPS was as follows： resident lifeatmospheric precipitationland uselivestock. For TP loads, the magnitude order was as follows： resident lifeland useatmospheric precipitationlivestock. Based on this, the characteristics of NPS and its impact on water environment quality in the island area were discussed. And, it could provide a technique method for the total amount of pollutants controland the healthy development of the island environment.