凉山州土壤重金属与粳稻中重金属相关性评价

Correlation Evaluation of Heavy Metals in Soil and Japonica rice in Liangshan Prefecture

采集四川省南部地区凉山州的土壤样本和粳稻样本共100个,通过测定土壤和粳稻中的砷(As)、铬(Cr)、镍(Ni)、铜(Cu)、锌(Zn)、镉(Cd)、铅(Pb)等7种重金属元素的含量,采用单因子污染指数法和内梅罗综合污染指数法对该地区土壤和粳稻进行重金属污染评价,以及土壤与粳稻中各重金属元素之间的相关性分析。结果表明:(1)四川南部地区土壤重金属Zn、Cd和Pb含量较高,是四川省土壤环境背景值的1.3倍、6倍和6.6倍,Cd和Pb的超标率较高,分别为60%和52%,根据内梅罗综合污染指数均值为1.6,得该地区整体处于轻度污染;从各重金属单因素污染指数得,Cd和Pb为轻微污染水平,As、Cr、Ni、Cu、Zn五种元素均处于无污染水平[1];(2)土壤中七种元素之间有显著的相关性,重金属累积的方式可能相同,有显著同源特性,重金属浓度变异系数为Pb(1.12)>As(0.89)>Cr(0.48)>Cd(0.48)>Ni(0.36)>Cu(0.28)>Zn(0.26),其中个别元素如As和Pb变异系数高,受局部污染源影响明显,空间差异性显著,重金属输入来源主要为人类活动;(3)粳稻中重金属As、Cd、Pb有局部点位存在超标情况,但总体上粳稻对土壤重金属的富集能力较低,受污染程度低。

A total of 100 soil samples and japonica rice samples were collected from Liangshan prefecture,southern Sichuan province.The contents of arsenic(As),chromium(Cr),nickel(Ni),copper(Cu),zinc(Zn),cadmium(Cd),and lead(Pb)in soil and japonica rice were determined.The heavy metal pollution of soil and japonica rice in this area were evaluated by single-factor pollution index method and Nemerow comprehensive pollution index method,and the correlation between the heavy metal elements in soil and japonica rice was analyzed.The results show that:(1)The contents of heavy metals Zn,Cd and Pb in the soil of southern Sichuan are higher,which are 1.3 times,6 times and 6.6 times of the background value of soil environment in Sichuan province,and the exceeding rates of Cd and Pb are relatively high,about 60%and 52%,respectively.According to the average value of the Nemero comprehensive pollution index of 1.6,the area as a whole is slightly polluted;according to the single-factor pollution index of each heavy metal,Cd and Pb are at mild pollution level,and As,Cr,Ni,Cu,and Zn are all at the pollution-free level.(2)There is a significant correlation between the seven elements in soil.Heavy metals may accumulate in the same way,and have significant homology characteristics.The coefficient of variation of heavy metal concentration is Pb(1.12)>As(0.89)>Cr(0.48)>Cd(0.48)>Ni(0.36)>Cu(0.28)>Zn(0.26).Among them,individual elements such as As and Pb have high coefficients of variation,which are significantly affected by local pollution sources,and have significant spatial differences.The main source of heavy metal input is from human activities.(3)The heavy metals As,Cd,and Pb in japonica rice have exceeded the standard at some local sites.But overall,japonica rice has low accumulation of heavy metals,so the level of pollution in japonica rice is low.