北京地区基本农田土壤环境质量分析与评价

对北京地区基本农田的土壤环境质量和污染状况进行了系统的调研，并对采样区农田土壤的环境质量按照国家标准进行了单因子评价和综合评价。结果表明，重金属的污染程度依次为Cd > Cu > As > Pb > Cr > Hg，Cd，Cu，As高于北京市土壤重金属背景值，Pb、Cr接近或略低于背景值，相比较而言，Cd污染为北京市基本农田中的主要污染元素。土壤中的农药残留的主要成分为滴滴涕。只有1处农田的Cd含量超过了国家二级标准限量，其余指标均低于二级标准。整体而言，北京地区的基本农田土壤环境质量属于清洁和安全范围，符合发展都市型现代农业的要求。

Analysis and assessment of soil environmental quality of some farmlands in Beijing

Forty-five surface soil samples in the farmland were collected from Beijing and analyzed for the concentrations of Cu, Pb, Cd, Cr, As, Hg, HCHs, and DDTs. The results of statistical analysis indicated that, among heavy metals, the pollution of Cd is the most serious, and then followed by this order Cd > Cu > As > Pb > Cr > Hg. Except Pb and Cr, other heavy metals concentrations exceeded the background levels in the area. Only in one place, the concentration of Cd exceeded the critical value of national soil quality standard. DDTs were the main pollution of Organochlorine pesticides. The comprehensive assessment shows that the soil environmental quality of farmland in Beijing is quite clean and safe for meeting the requirement of developing metropolitan modern agriculture.