安徽某地山核桃园地土壤重金属生态风险评价

ASSESSMENT OF ECOLOGICAL RISK OF HEAVY METALS IN THE SOIL OF A CHINESE WALNUT PLANTATION IN ANHUI PROVINCE

研究区是我国山核桃重要产地,在区内开展生态风险评价对保障山核桃食品安全具有重要意义。采集山核桃果仁及对应的根系土壤样品各82件,分析土壤和山核桃样品中重金属含量,以《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB 15618—2018)中pH≤5.5非水田条件下的风险筛选值为标准,评价土壤重金属污染程度和潜在生态风险。结果表明:研究区山核桃园地土壤中Cd、Cr、Hg、As、Pb、Cu、Zn、Ni等8种重金属平均含量均高于中国土壤平均值,其中As、Cd分别为中国土壤平均值的3.80倍、2.90倍。研究区局部土壤中As、Cd、Pb、Zn、Ni含量出现不同程度的超标,其中Cd超标较为显著,As、Pb、Zn、Ni超标程度低,Cr、Hg、Cu未超标。Cd达到中等生态危害程度,其他重金属生态风险低。土壤重金属生态风险总体较低,风险可控。研究区山核桃果仁中Cd、Cr、Hg、As、Pb含量总体较低,少量山核桃果仁样品中出现Pb含量超标,应加以关注。

The study area is an important producing area of the Chinese walnut in China.It is of great significance to carry out ecological risk assessment in the area to ensure the food safety.Respective 82 samples of the walnuts and the corresponding root soils were collected to analyze the heavy metal contents therein.The risk screening value of pH≤5.5 in the Soil Environmental Quality Management and Control Standard for Soil Pollution Risk in Agricultural Land(Trial)(GB 15618-2018)was used as the standard to evaluate the pollution degree and potential ecological risk of heavy metals in soil.The results showed that the average contents of 8 heavy metals such Cd,Cr,Hg,As,Pb,Cu,Zn and Ni in the soil of walnut plantation in the study area were higher than the average of Chinese soil,in which As and Cd were 3.80 times and 2.90 times of the average of Chinese soil,respectively.The contents of As,Cd,Pb,Zn and Ni in local soils in the study area were above the standards to different degrees,among which the content of Cd was significantly above the standard,the contents of As,Pb,Zn and Ni were a bit higher and the contents of Cr,Hg and Cu were normal.Cd has reached a moderate level of ecological harm,while the ecological risk of other heavy metals is low,and the ecological risk of heavy metals in soil is generally low and controllable.The contents of Cd,Cr,Hg,As and Pb in walnuts in the study area were generally low,and the Pb content in a few walnut samples exceeded the standard,to which attention should be paid.