北京市农田土壤重金属年际差异分析与评价

Annual Variability Analysis and Evaluation of Heavy Metals in Beijing Agricultural Soil,China

通过对2005年至2009年北京市农田土壤重金属含量的持续监测,分析了该地区农田土壤中As、Hg、Cu、Cd、Cr和Pb等重金属的统计特征和年度变化趋势,并结合国家土壤环境质量标准,对农田环境质量进行了评价。结果表明,2005年至2009年间,As、Hg、Cu、Cd、Cr和Pb等重金属中,Hg和Cr的含量有逐年上升的趋势,Hg的平均含量逐年为0.053、0.066、0.070、0.072 mg.kg-1和0.079 mg.kg-1,Cr平均含量为50.0、52.4、55.3、58.6 mg.kg-1和62.1 mg.kg-1。其他重金属含量上下波动,无上升或下降的变化趋势。结合重金属含量统计和单因子评价结果,重金属的污染程度依次为Cd>Hg>Cu>Pb>Cr>As。北京农田整体处于清洁状态,但存在着个别的Hg和Cd污染。

The statistical characteristics and annual variability of heavy metals As,Hg,Cu,Cd,Cr,and Pb in Beijing agricultural soil were presented,on the basis of continuous yearly monitoring for the period of 2005 to 2009.Heavy metals were evaluated using the single-factor pollution index and based on the national environmental quality standard for soils.The results showed a growth of Hg and Cr in Beijing agricultural soil from 2005 to 2009,while the concentration of Hg was 0.053,0.066,0.070,0.072 mg·kg-1 and 0.079 mg·kg-1,and Cr was 50.0,52.4,55.3,58.6 mg·kg-1 and 62.1 mg·kg-1,respectively.There was no significant trend for other metals.Furthermore,combined statistical characteristics of metals and the evaluated results of single-factor index,Cd was found to accumulate in soil the most,followed by Hg,Cu,Pb,Cr and As.These results indicted the environmental quality of Beijing agricultural soil was mostly clean and safe,except several samples were polluted by Hg and Cd.