成都平原农田蔬菜重金属含量及污染评价

Heavy metal contents and pollution evaluation of farmland vegetables in Chengdu Plain

为降低重金属污染风险,保证蔬菜生产安全,调查了成都平原部分污染地区蔬菜种植地土壤和5类18种蔬菜可食部位重金属含量,并对蔬菜中重金属污染状况进行了评价,同时运用富集系数分析和比较了不同蔬菜对Cd、Cr、Pb、Zn、Cu、Ni、Hg、As的富集能力。结果表明:试验区域土壤Cd含量超标率达31.91%,Cd是主要污染物,其余元素均符合国家标准。所有蔬菜可食部位主要受重金属Cr、Hg、Cd污染,轻微污染的有蒜苗和油菜,轻度污染的有菠菜和香菜;通过富集系数发现,18种蔬菜对8种重金属元素的富集系数平均值均从高到低依次为Cd>Zn>Hg>Cu>Ni>As>Cr>Pb,且不同蔬菜对同一种元素的富集系数也表现显著性差异。总体上,叶菜类蔬菜如香菜对Cd、Hg、Pb、Cr、Ni、Zn、Cu和菠菜对Cd、Hg、Zn、Pb、Cu以及红油菜对As、Pb富集能力相对较强,表明研究区域香菜和菠菜不宜在Cd、Hg、Pb、Cr、Ni、Zn、Cu污染土壤上栽培,及红油菜不宜在As、Pb污染土壤上栽培,而甘蓝类和根茎类如包心菜对Cd、Hg、Cr、Pb、As、Ni、Cu和白萝卜对Cd、Cr、Zn、Cu、Ni、Hg及红萝卜对Zn、Cr、Cu富集能力则相对较弱,可作为研究区域Cd、Hg、Cr、Pb、As、Ni、Cu、Zn污染土壤优先选种的蔬菜品种。

In order to reduce the risk of heavy metal pollution and ensure the safety of vegetable production,the heavy metal contents in the soil and the edible parts of 18 varieties under 5 types of vegetables were determined,and the status of heavy metal pollution in the vegetables were evaluated.Meanwhile an enrichment coefficient was used to analyze and compare the capacity of the vegetables to accumulate the heavy metals Cd,Cr,Pb,Zn,Cu,Ni,Hg and As.The results showed that the soil Cd content in the area under experiment was 31.91%,which was the main pollutant,while the contents of other heavy metals fell within the national standards.The edible parts of all vegetables were mainly contaminated,and garlic and rape,spinach and coriander were slightly contaminated by heavy metals Cr,Hg,and Cd.The enrichment coefficients of the 8 heavy metals in the vegetables showed that the average enrichment coefficient of the heavy metals in 18 varieties of vegetables was in the descending order of Cd>Zn>Hg>Cu>Ni>As>Cr>Pb.The average enrichment coefficient of Cd was 0.2011 and Pb was 0.0031,a difference of 64.66 times between Cd and PB.The enrichment coefficient of the same element in different vegetables showed significant difference which was up to 120 folds.Generally,leaf vegetables such as coriander had a relatively higher enrichment capacity for Cd,Hg,Pb,Cr,Ni,Zn,Cu,and spinach for As and Pb,which indicates that coriander and spinach in the experimental area should not be cultivated on the soil contaminated with Cd,Hg,Pb,Cr,Ni,Zn and Cu.Red rape should not be cultivated on the As and Pb contaminated soil,However,cabbage and root vegetables,such as cabbage,white radish and carrot,had a weak capacity to accumulate Cd,Hg,Cr,Pb,As,Ni and Cu;Cd,Cr,C n,Cu,Ni and Hg;and Zn,Cr,and Cu,respectively,and can hence be used as the priority varieties of vegetables cultivated in the soils contaminated with Cd,Hg,Cr,Pb,As,Ni,Cu,and Zn in the experimental area.