贵阳市表层土壤中镉的环境地球化学基线研究

以土壤环境地球化学研究为主线,以贵州省贵阳市8　046　km²为研究区域,将土壤重金属污染元素镉的空间分布规律与环境地球化学机理研究相结合,建立区域土壤环境地球化学基线,选用合适的判别指标判识自然作用过程与人类活动过程对土壤环境的影响.通过对487个样品的镉含量的统计分析,结果表明,贵阳市表层土壤中镉的基线值为0.068　mg/kg,镉元素含量大于1.010　mg/kg的样品可能遭受人为污染的影响.地质累积指数分析结果显示,贵阳市40%的表层土壤未受镉污染,19%的表层土壤在无污染与中度污染之间,14%受中度污染,19%的表层土壤介于中度污染到强污染之间,7%受强污染,1%的表层土壤介于强污染到极强污染之间.污染程度指数分析则显示,贵阳市57.9%的表层土壤未受到镉污染,镉的污染程度最大为12.1,96%的表层土壤污染程度小于4,总污染程度大于0,即总体受到污染.

Geogenic Distribution and Baseline Concentrations of Cadmium in Surficial Soil of Guiyang, China

The characteristics of environmental geochemistry of heavy metal pollutant cadmium (Cd) in the surficial soil of Guiyang, Guizhou, China was studied. The baseline concentration of Cd in soil and the geochemistry norms have been established to distinguish the nature or artificial influence on the environment. The statistical analysis indicated that the baseline of Cd in Guiyang was 0.068 mg/kg. Geoaccumulation index analysis indicated that the unpolluted surface soils accounts for 40%, and 19% between nonpollution to mid-pollution, 14% for mid-pollution, 19% between mid-pollution to severe pollution, 7% for severe pollution, only 1% between severe pollution to super severe pollution. The maximum of Cd contamination degree (CD) is 12.1. CD analysis indicated that the unpolluted surface soils accounts for 57.9%.