摘要：

为掌握河北省典型区域农田土壤和农产品重金属积累特征及潜在风险,分别采集金属冶炼区、污灌区和蔬菜区的土壤和农产品样品,测定重金属As、Pb、Cr、Cd、Hg、Cu、Zn含量及土壤pH值,通过单因子污染指数、内梅罗综合污染指数法,进行土壤环境质量及农产品安全性评价。结果表明,7种重金属的单项污染指数由大到小依次为Cd、Zn、Cu、As、Cr、Pb、Hg,个别土壤样点Cd、Pb、Cu、Zn的单项污染指数大于1.0,环境质量等级处于Ⅲ级以上,土壤Cd点位超标率最高,为18.51%。冶炼区土壤Cd、Cu、Pb、Zn元素超标,超标率分别为92.31%,69.23%,34.62%和26.92%。污灌区土壤Cd、Zn元素累积最明显,超标率均为8.70%。蔬菜区土壤Cd元素累积最明显,超标率为9.94%。总体上看,河北省典型区域农田7种土壤重金属的综合污染指数为0.64,土壤环境质量等级处于Ⅰ级,清洁。冶炼区、污灌区和蔬菜区土壤环境质量等级分别处于Ⅲ级(轻度污染)、Ⅰ级(安全)和Ⅰ级(安全)。参照相关的食品安全标准(NY 861—2004、GB2762—2022),冶炼区周边小麦籽粒Pb、Cd和Zn的超标率分别为40.00%,40.00%和60.00%。污灌区小麦籽粒Zn、Pb、Cd元素出现超标,超标率分别为57.45%,8.51%和6.38%。蔬菜种植区蔬菜样本未出现重金属超标现象。因此,冶炼区和污灌区土壤环境质量状况和农产品质量安全应引起足够重视。

关键词: 土壤, 重金属, 农产品, 典型区域, 积累特征, 风险评价

Abstract:

In order to understand the characteristics and potential risks of heavy metals accumulation in farmland soils and agricultural products in typical areas of Hebei Province,soil samples (0—20 cm)and agricultural products were collected from metal smelting areas,sewage irrigation areas and vegetable areas,the contents of heavy metals Cr,Cd,Pb,As,Hg,Cu,Zn and soil pH were determined. The environmental quality of farmland soil in typical areas of Hebei Province was evaluated by the method of combining single-factor pollution index with nemerow comprehensive pollution index,the safety of agricultural products was evaluated. The results showed that the descending order of single pollution index of 7 heavy metals was Cd,Zn,Cu,As,Cr,Pb and Hg,and the single pollution index of Cd,Pb,Cu,Zn in some soil samples was more than 1.0,the environmental quality was above grade Ⅲ,and the rate of exceeding the standard of soil Cd was the highest (18.51%). Cd,Cu,Pb and Zn in the soils of the smelting area exceeded the standard,and the exceeding rate was 92.31%,69.23%,34.62% and 26.92%,respectively. The accumulation of Cd and Zn in the soil of sewage irrigation area was the most obvious,and the over-standard rate was 8.70%. The accumulation of Cd in vegetable soil was the most obvious,and the over-standard rate was 9.94%. Overall,the comprehensive pollution index of 7 heavy metals in farmland of Hebei Province was 0.64,and the soil environmental quality was in grade Ⅰ,which was clean. The soil environmental quality grades of smelting area,sewage irrigation area and vegetable area were in grade Ⅲ(light pollution),Grade Ⅰ(safety)and Grade Ⅰ(safety),respectively. According to the relevant food safety standards (NY 861—2004,GB2762—2022),the excess rates of Pb,Cd and Zn in wheat grains around the smelting area were 40.00%,40.00% and 60.00%,respectively. The excess rates of Zn,Pb and Cd in wheat grains were 57.45%,8.51% and 6.38%,respectively. The content of heavy metals in all vegetables in the vegetable area was not exceeding the standard,and the quality of vegetables is safe. Therefore,the soil environmental quality and the quality safety of agricultural products in smelting and sewage irrigation areas should be paid enough attention.

Key words: Soil, Heavy metals, Agricultural products, Typical area, Accumulation characteristics, Risk assessment