Distribution and Pollution of Heavy Metals in Soil-crop Systems in Dushan County,Guizhou Province
To benefit agricultural planning and guarantee food safety in Dushan County,totally 120 crop 120 rhizosphere soil samples,10 soil profile and 10 ore parent rock samples were collected to examine for heavy metal(loid)s(As,Cd,Cr,Cu,Hg,Ni,Pb,and Zn),as well as organic matter concentrations and pH value.We evaluated the heavy metal(loid)pollution using the single-factor index method,geo-accumulation index method,crop enrichment factor,and health risk assessment method.Our findings indicate that:(1)In Dushan County,the highest concentrations of As,Cu,Hg,and Zn were found in tomato rhizosphere soils,averaging 21.38,22.18,0.42,and 110.39 mg/kg respectively.The highest Cd,Cr,Ni,and Pb concentrations were found in corn rhizosphere soil with mean values of 1.05,111.12,29.02,and 34.50 mg/kg respectively.The pH of rhizosphere soils ranged from 3.58 to 8.24,with 87.5％of samples showing a pH value below 6.5,indicating overall a slight acidity.Single-factor index analysis revealed"slight to moderate pollution"levels of Cd in rhizosphere soils,as well as"slight to moderate pollution"of Cd in soils and crops.Geo-accumulation index results showed that human activities influenced As,Cd,Hg,and Zn levels in crop rhizosphere soils.(2)Among the 120 crops,rice and corn exhibited the highest exceedances of Cd standards(33.33％for rice,13.33％for corn),followed by Pb(3.33％for rice),and Cr(30.00％).No exceedances were found in grapes,tea,and tomatoes.Crop enrichment factors indicated that Cd enrichment was several times to hundreds of times higher than that of As,Cr,and Pb,highlighting strong Cd and Pb uptake capacities in crops,especially for Cd.Health risk assessment values for As,Cd,Cr,Hg,and Pb in crops for both adults and children were all below 1,indicating no health risks associated with heavy metal(loid)uptake by crops.
万方数据
维普
