Bioavailability And Health Risk Assessment Of Heavy Metals In Soil Of Primary Schools In Jiaozuo

The present situation of soil heavy metal pollution in the school area was studied in this paper,taking the school soil of Jiaozuo as the research object.Soil pollution of schools in Jiaozuo was evaluated by using the method of land accumulation index,enrichment factor and potential ecological risk assessment.The source of heavy metal in the school soil was discussed by principal component analysis(PCA)and correlation method.Then,in vitro simulation experiment(physiogically based extraction test-PBET)was used to explore the bioavailability of heavy metals in soil.Finally,the health risk assessment model was applied to evaluate the health risk based on the total amount of soil heavy metals and bioavailability.The conclusions are drawn as follows:1)The average contents of Zn,Cu,Mn,As,Pb,Cd,Cr,Ni and Co in school soil in Jiaozuo are 141.5 mg/kg,22.4 mg/kg,507.4 mg/kg,48.59 mg/kg,36.1 mg/kg,0.62 mg/kg,76 mg/kg,38 mg/kg,14.7 mg/kg,respectively.It is 2.29 times,1.13 times,0.89 times,5.17 times,1.66 times,8.86 times,1.22 times,1.78 times,1.22 times of the background value respectively.Among them,Zn,Cd and Cr showed high variation.Pb,As,Cu,Mn and Ni were moderately variable,Co and Ti showed low variability,reflecting heavy metal interference in Jiaozuo school area.2)Enrichment factor method,geo accumulation index method,and potential ecological risk assessment results show that As?Cd?Zn pollution is serious in Jiaozuo school area.Cu,Mn,Cr,Pb,Ni and Co are moderately or lightly polluted.3)The source apportionment of heavy metals in school soil,As,Cd,Ni and Co were greatly influenced by coal sources,and Zn and Cu were greatly influenced by traffic.4)Bioavailability analysis showed that the bioavailability of heavy metals in the Jiaozuo school area was between 0.9%~41.39% and 0.41%~32.88% in the intestinal stage.The bioavailability of heavy metal elements of Zn,Mn,As,Pb,Cd,Cr,Ni and Co has a gastric stage > intestinal stage as a whole,and the bioavailability of Cu is in the intestinal stage > gastric stage.5)According to the health risk assessment based on the total amount of heavy metals in soil,the non carcinogenic risk of As is more than 1,and the other Cr,Pb,Ni,Cd,Zn,Co and Cu are less than 1,and there is no non carcinogenic risk.Cr,As and Co all have carcinogenic risk.The carcinogenic risk of Cd and Ni is within acceptable limits.6)The health risk assessment of soil heavy metals based on bioavailability correction showed that the non carcinogenic risk of Zn,Cu,As,Pb,Cd,Cr,Ni and Co decreased by 95.54%,85.29%,87.45%,98.97%,90.04%,98.18%,92.18%,95.49%,and the total non carcinogenic risk merchants were reduced by 89.57%.After correction,the carcinogenic risk of As,Cd,Cr,Ni and Co decreased by 87.45%,90.04%,98.18%,92.18% and 95.49% respectively.The total risk of cancer was reduced by 96.11%.