冀东典型蔬菜种植区设施土壤重金属特征

目的探究冀东典型蔬菜种植区(唐山市和承德市)设施土壤重金属特征。方法对设施大棚进行调查并采集表层土壤样品,检测其重金属,即镉(Cd)、汞(Hg)、砷(As)、铅(Pb)、铬(Cr)、铜(Cu)、锌(Zn)含量,并依据HJ/T 333—2006《温室蔬菜产地环境质量评价标准》进行了土壤质量评价。结果除As外,其他重金属均超过河北省土壤背景值(国家环境保护局),最高为Hg,为背景值的3.46倍。Cd与棚龄呈显著负相关关系(P<0.05)。从地理分布来看,Hg呈现西高东低的分布特征,而As、Pb则呈现南高北低的分布特征。从重金属单项质量指数来看,Cd、Hg、As、Cr、Zn均未超标;Cu、Pb超标率分别为7.37%和22.11%,属轻度污染。从重金属综合质量指数看,3.16%的土壤为超标土壤,属轻度污染,超标率较高的区县为隆化县、乐亭县、滦平县、宽城县和滦南县,重金属综合质量指数与土壤pH呈极显著负相关关系(P<0.01)。结论冀东典型蔬菜种植区设施土壤存在Cu、Pb的轻度污染现象,后续需要对蔬菜中的Cu、Pb进行调查以评估蔬菜产品的安全性。

Characteristics of heavy metals in greenhouse soils on typical vegetable cultivation regions of east Hebei

Objective To investigate the characteristics of heavy metals in greenhouse soils on typical vegetable cultivation regions of east Hebei(Tangshan city and Chengde city).Methods Surface soil samples were collected and detected for heavy metals(Cd,Hg,As,Pb,Cr,Cu,Zn),and the soil quality was assessed with the HJ/T 333—2006 Environmental quality evaluation standards for farmland of greenhouse vegetables production.Results The heavy metal concentrations were higher than the background values of Hebei province except As,and the highest was Hg which was 3.46 times higher than the background value.Significant negative correlation was found between Cd and the service life of greenhouse(P<0.05).Hg decreased from west to east,while As and Pb decreased from south to north geographically.According to the single quality index of heavy metal,Cd,Hg,As,Cr,Zn of soils were all under the limit levels.Soil samples were found to exceed the environmental quality evaluation standards(mild contaminated)for Cu or Pb,and the over-limit ratios were 7.37%and 22.11%,respectively.According to the comprehensive quality index of heavy metals,3.16%of the soils were over limit and mainly distributed in Longhua county,Laoting county,Luanping county,Kuancheng county and Luana county.Extreme significant negative correlation was found between pH values and the comprehensive quality index of heavy metals(P<0.01).Conclusion Mild contamination for Cu or Pb were found in greenhouse soils on typical vegetable cultivation regions of east Hebei,and subsequent investigations on Cu and Pb in vegetables should be carried out to evaluate the safety of vegetable products.