基于输出系数模型的北京地区农业面源污染负荷估算

农业生产活动产生的面源污染物是环境污染负荷的主要来源之一。利用输出系数模型对北京市农业面源污染负荷进行了估算。结果表明，2006年北京市农业面源污染物总氮和总磷负荷量分别是19 565.7×106和2 413.1×106 g/a。土地利用方式显著影响氮和磷负荷，不同污染源类型对污染负荷贡献的差异较大。不同污染源类型对总氮污染负荷贡献率的大小顺序为农村生活污水及废弃物＞耕地＞林地＞畜禽养殖＞园地＞牧草地，对总磷负荷贡献率的大小顺序为农村生活污水及废弃物＞畜禽养殖＞耕地＞林地＞园地＞牧草地。各区县总氮和总磷负荷量和负荷强度的差异较大，其中大兴、顺义、房山、密云和通州的总氮和总磷负荷量较大，而朝阳、丰台、通州、顺义和大兴的总氮和总磷负荷强度较大。农业面源污染物氮和磷分布状况和负荷强度的研究，为北京地区区域规划和农业结构调整提供了科学依据。

Estimation of pollution loads from agricultural nonpoint sources in Beijing region based on export coefficient modeling approach

Nonpoint source pollutants produced from agricultural production activity is one of the major pollutant sources for environmental pollution. Pollution loads from agricultural nonpoint sources in Beijing City were estimated according to the approach of export coefficient modeling. The results demonstrated that total nitrogen and total phosphorus loads in Beijing City respectively were 19565.7 and 2413.1 Mg a-1 in 2006. Total nitrogen and phosphorus loads was affected by types of land utilization significantly . The contributions to pollution load from various types of pollutant sources were different. The magnitude order of the contribution from various types of pollutant sources was wastewater and garbage from rural residents > cultivated land > forest land > livestock and poultry breeding > garden plot > grassplot for total nitrogen load, and wastewater and garbage from rural residents > livestock and poultry breeding > cultivated land > forest land > garden plot > grassplot for total phosphorus load, respectively. The differences among various districts/counties in Beijing about total nitrogen and total phosphorus loads and their load intensities were great. Total nitrogen and total phosphorous loads in Daxing, Shunyi, Fangshan, Miyun, and Tongzhou Districts were bigger, and the load intensities of total nitrogen and total phosphorous in Chaoyang, Fengtai, Tongzhou, Shunyi, and Daxing Districts were higher. The research about the distribution of nitrogen and phosphorous pollutants and their load intensities from agricultural nonpoint sources can provide a foundation on regional planning and agricultural structure adjustment in Beijing region.