重庆市植烟土壤重金属含量特征及污染评价

Heavy Metal Content Characteristics and Pollution Evaluation in Tobacco Planting Soil of Chongqing

对重庆市植烟土壤中8种重金属元素的含量特征进行了调查研究,并采用标准对比法和地质累积指数法对其污染状况进行了评价。结果表明,重庆市植烟土壤中8种重金属元素的平均值分别为:As 12.78 mg/kg,Cd0.492 mg/kg,Cr 83.62 mg/kg,Cu 32.91 mg/kg,Hg 0.141 mg/kg,Ni 34.74 mg/kg,Pb 36.42 mg/kg,Zn 93.62mg/kg,且均高于其土壤背景值,变异系数以Hg,Cd最大,分别为80.94%和61.36%,元素分布极为不均。通过重金属相关性分析,大部分元素两两之间均呈现显著或极显著正相关,存在土壤复合污染的特征。采用两种方法评价均发现,重庆市植烟土壤中的Cd污染相对较为严重,轻度污染至中度污染的土壤样本数达90%以上,As,Hg,Pb 3种金属元素的环境质量则处于无污染至轻度污染的状况,而Cr,Cu,Ni,Zn 4种重金属元素环境质量相对较好,均处于土壤清洁的安全状态。

Through the methods of field sampling and laboratory analysis, the objectives of this study were to investigate the content characteristics of eight heavy metals in tobacco planting soil of Chongqing, at the same time evaluate the pollution degree of these heavy metals based on the evaluation factors of standard comparison and Geoaecumulation index （Igeo）. The results indicated that the average concent of eight heavy metals in the tobacco planting soil of Chongqing were As 12.78 mg/kg,Cd 0. 492 mg/kg,Cr 83.62 mg/kg,Cu 32.91 mg/kg,Hg 0. 141 mg/kg,Ni 34.74 mg/kg, Pb 36.42 mg/kg,Zn 93.62 mg/kg, respectively, which were all higher than the background value of Chongqing soil. The variation coefficient of Hg and Cd were the highest, the value was 80.94% and 61.36% respectively, which showed that the maldistribution of Hg and Cd in soils was extremely abvious. Based on the correlation analysis of eight heavy metals, there was a sig- nificant or extremely significant positive correlation between most of the eight heavy metals, it indicated that there was a feature of combined pollution in tobacco planting soil of Chongqing. According to the two evaluation methods, it can be found that the pollution degree of Cd was more serious than other seven heavy metals correspondingly, and the soil sample percentage of slight and moderate pollution was beyond 90%. The environmental quality condition of As, Hg and Pb was at the level of no pollution and slight pollution, and the environmental quality condition of Cr, Cu, Ni and Zn was correspondingly better, they were at the safety state of clean soil.