Categorization Of Heavy Metal Pollution Risk Control In The Soil Of Pepper Planting Areas

In this study,using coordinated monitoring,108 pairs of soil and pepper samples were collected from the cultivated soil of pepper planting areas in a county of Guizhou Province,and their respective full and effective levels of such eight heavy metal elements as Cd,Hg,As,Pb,Cr,Cu,Zn and Ni,were measured.Using the land use maps,geological maps and remote sensing image maps,the full and effective states of the eight heavy metal elements in the soil and the heavy metals in the peppers of the study areas were divided into environmental risk control categories based on specifications listed in the Soil Environmental Quality Soil Pollution Risk Control Standard for Agricultural Land(Trial Implementation)(GB15618-2018),Classification of Heavy Metal Pollution in Soil of Agricultural Products Origin(DB35/T 859-2016)and National Standard for Food Safety Pollutant Limits in Food(GB2762-2017).and then the results of the soil heavy metal effective states and pepper risk categories were combined to adjust the soil environmental risk control categories,resulting in the risk control categories of heavy metal pollution in the pepper growing areas.The main conclusions are as follows.(1)The full amounts of the eight heavy metals Cd,Hg,As,Pb,Cr,Cu,Zn and Ni in the study areas ranged from 0.26-6.51mg/kg,0.03-1.58mg/kg,2.49-349.20mg/kg,13.62-80.32mg/kg,30.39-379.33mg/kg,9.83-108.18mg/kg,43.24-245.38mg/kg,16.16-215.62mg/kg,among which the Hg and Pb content of soil spots did not exceed the risk screening value of soil pollution in agricultural land;9.26%,82.41%,99.07%,71.3%,99.07% and 92.59% of the spots of Cd,As,Cr,Cu,Zn and Ni were classified as category of priority protection;87.96%,14.81%,0.93%,28.7%,0.93% and 7.41% of the spots were category of safe use;2.78% of the spots of Cd and As were category of strict control.(2)Using spatial interpolation to categorize the environmental risk control of heavy metals in soil in the study areas,2.53%,100%,88.01%,100%,99.9%,82.19%,100% and 98.73% of agricultural map spots in Cd,Hg,As,Pb,Cr,Cu,Zn and Ni were category of priority protection;94.29%,10.81%,0.1%,17.81% and 1.62% of agricultural map spots in Cd,As,Cr,Cu and Ni were category of safe use;3.18% and 1.18% of agricultural map spots in Cd and As were category of strict control.(3)The content of effective states of heavy metals Cd,Hg,As,Pb,Cr,Cu,Zn and Ni in the study areas are 0.02-2.0mg/kg,0.01-0.15mg/kg,0.12-4.13mg/kg,0.28-20.09mg/kg,0.001-0.47mg/kg,0.47-12.33mg/kg,0.38-16.03mg/kg,0.01-6.66mg/kg,of which the effective states of Cr and Zn at the soil spots do not exceed the safety value;For Cd,Hg,As,Pb,Cu,Ni,51.85%,56.48%,94.44%,99.07%,99.07%,49.07% of the soil points are at the safe level;for Cd,Hg,As,Pb,Cu,Ni,33.33%,31.48%,3.70%,0.93%,0.93%,47.22% of the soil spots are at the alert level;For Cd,Hg,As,Ni,11.11%,12.04%,1.85%,2.78% of the soil spots are at the restricted level;for Cd and Ni,3.70% and 0.93% of the soil spots are at the high-risk level.(4)The content of heavy metals Cd,Hg,As,Pb,Cr,Cu,Zn,Ni in peppers are 0.01-1.22mg/kg,0,0.0004-0.0158mg/kg,0.01-0.03mg/kg,0.01-2.50mg/kg,0.07-4.90mg/kg,1.00-9.67mg/kg,0.05-5.18mg/kg,where the content of As,Pb,Cu,Zn elements did not exceed the relevant standards;for Cd,Hg,Cr,Ni,14.81%,99.07%,82.41%,and 71.3% of the pepper samples did not exceed;for Cd,Hg,Cr,and Ni,36.11%,0.93%,and 11.11% of the pepper samples slightly exceeded standards;for Cd,Cr,and Ni respectively,49.07%,6.48%,7.41% of the pepper samples severely exceeded standards.(5)The results of the soil pollution risk control categories based on full soil heavy metals,soil heavy metals active state,and crop heavy metals content were not consistent and were significantly different.The adjustment based on the soil heavy metals active state can significantly reduce the area of agricultural map spots in the safe use category,but does not objectively represent the soil pollution risk control category;the adjustment of the pepper heavy metals evaluation results in a decrease in the strict control category and safe use category for As,Cu agricultural map spots,but an increase in the safe use category for Cd,Cr,Ni agricultural map spots;The use of crop heavy metal content for soil contamination risk management categories is shown to be more credible in high background value areas.