重金属面源污染模拟及其不确定性分析——以湘江株洲段镉污染为例

基于我国现有的环境数据条件，将复杂的分布式水文、泥沙模拟（采用SWAT模型）与简化的输出系数方法进行有效整合，建立了可实际应用的流域重金属面源污染负荷模型。应用所建模型对湘江株洲段所属汇水区域的镉面源污染进行动态模拟，并进行不确定性分析。模拟结果显示，研究区镉面源污染负荷总量约为2 435kg/a，受污染土壤对于镉面源负荷量贡献率达657%。土壤侵蚀过程对研究区的面源污染过程起控制作用，因此，土壤污染防治和水土保持是该区域镉面源污染管理的关键。土壤污染程度高且易侵蚀的地区（如清水塘工业区及其邻近地区）是防治的重点区域，而每年的4月和5月是防治的重点时期。不确定性分析结果显示，超过50%的概率下，研究区镉面源负荷总量处于2 000～3 000 kg/a这一范围，但仍有可能低于1 500 kg/a或高于4 000 kg/a

SIMULATION OF THE NONPOINT SOURCES LOAD OF HEAVY METALS AND ITS UNCERTAINTY ANALYSIS ——A CASE STUDY OF CADMIUM POLLUTION AT THE XIANGJIANG RIVER IN THE ZHUZHOU CITY

Based on the current condition of environmental data in China,this study developed a practical model for calculating watershed nonpoint sources load of heavy metals.The model integrates complex hydrology and sediment simulations(using the SWAT model) with simple export coefficient approaches.The model was applied to the cadmium pollution at the drainage area of the Xiangjian River in the Zhuzhou City,China.The uncertainty of the model simulations was also analyzed.The results showed that the total nonpoint sources load of cadmium at this area was about 2 435 kg/a,and the polluted soil was the major source which accounted for 65.7% of the total load.The nonpoint sources pollution was mainly controlled by the soil erosion process,and thus soil pollution prevention and conservation should be the key measures for controlling the nonpoint source pollution.The locations with highly polluted soil and/or those vulnerable to soil erosion(such as the Qingshuitang Industrial Park and its surrounding areas) were the critical zones for the pollution control,and April and May were the critical periods.The uncertainty analysis revealed that,with a probability of over 50%,the total nonpoint sources load was within the range of 2 000~3 000 kg/a,but there was still a possibility that the load was below 1 500 kg/a or over 4 000 kg/a.