Bioaccessibility And Health Risk Assessment Of Heavy Metals In Soil Of Jiaozuo City Parks

The paper takes the soil of Jiaozuo city parks as the research object,study on the pollution status of heavy metals in the soil of the city parks,and use the single pollution index and comprehensive pollution index and potential ecological risk assessmentmethods to evaluate the soil pollution status of the parks,and the PBET test for heavy metal bioaccessibility analysis.The health risk assessment of heavy metals in three ways was carried out by using the EPA health risk assessment model combined with the risk assessment parameters of human health in China.In addition,the bioaccessibility of heavy metals in the intestinal stage of the experiment in vitro is also amended toevaluate the risk of human health.In the end,the source of soil heavy metals in Jiaozuo was preliminarily discussed with the methods of enrichment factor,correlation analysis and principal component analysis.The conclusions are as follows:?1?The average contents of Zn,Cu,Mn,As,Pb,Cd,Cr,Ni and Co in Jiaozuo Park soil are 79.42 mg/kg?19.97 mg/kg?453.47 mg/kg?47.89 mg/kg?24.92 mg/kg?0.40mg/kg?47.83 mg/kg?35.54 mg/kg and 17.19 mg/kg,among them the average content of Zn,As,Cd,Ni and Co were 1.28 times,4.39 times,5.88 times,1.18 times and 1.59times of the soil background value,respectively;the content of Cu and Pb is close to the background value,only the content of Mn and Cr is lower than the soil background.Compared with the accumulation of heavy metals in other urban parks,the cumulative degree of Jiaozuo parks is lower than that of Xinxiang parks,which is higher than that of other urban parks,in particular,the high accumulation of Cr and As should cause people to pay great attention to it.?2?The results of single pollution index showed that the degree of heavy metal pollution was Cd>As>Co>Zn>Pb>Ni>Cu>Cr>Mn and the pollution of Cd and As in heavy metals of Jiaozuo parks was more serious.The comprehensive pollution index shows that the comprehensive pollution index of the parks is bigger than 3,which means a serious pollution.The comprehensive pollution index of the Renmin Park is the largest,and the pollution index of Forest Park is the smallest.The order of soil pollution in the park is Renmin park>Longyuanhu park>Fengshanzhen park>Diaosu park>Yueji park>Forest park.Through the calculation of the potential risk index of heavy metals in Jiaozuo parks,it is found that the ecological risk of Cd is the largest.The potential risk of Cd in Renmin Park belongs to the extremely strong,and the Cd of Longyuanhu Park,Diaosu park,and Fengshanzhen park also has strong ecological risk.Secondly,As and Co also have a large pollution.From different parks,the potential risk index of the Renmin park is the largest,and its pollution is at a strong ecological risk,the degree of pollution in the other 5 parks is moderate.?3?The bioaccessibility of heavy metals in Jiaozuo parks soil showed that:at the gastric stage,the bioaccessibility of Zn,Cu,Mn,As,Pb,Cd,Cr,Ni,and Co is5.58%¹6.58%?86.94%¹70.86%?12.57%³5.10%?5.07%²7.71%?7.52%⁴1.44%?4.60%³5.47%?1.56%⁷.88%?4.30%¹1.99%?3.31%⁷.37%,respectively,the largest bioaccessibility element is Cu,and the smallest is Cr.In the intestinal stage,the bioaccessibility of heavy metal is 1.36%⁷.59%?102.99%²59.42%?10.71%²2.46%?5.57%²1.32%?0.42%².99%?4.33%⁴7.80%?1.65%⁶.88%?3.90%⁷.01%?1.77%³.09%and the largest bioaccessibility of element is Cu,and the smallest is Pb.Combined with the bioaccessibility of heavy metals in the gastric and intestinal phases,it can be found that the bioaccessibility of Zn,Mn,As,Pb,Cr,Ni and Co in the gastric phase is higher than that in the intestinal phase.?4?The results of health risk assessment showed that the heavy metal elements which caused the most non-carcinogenic risk were Mn and As for adults and children in Jiaozuo parks.In different ways,adults have the greatest non-carcinogenic risk caused by respiratory pathways,and the most non-carcinogenic risk in children is hand-mouth pathway.Jiaozuo city parks non-carcinogenic risk order is Longyuanhu park>Forest park>Renmin park>Yueji park>Diaosu park>Fengshanzhen park.The total risk of non-carcinogenic in both children and adults was greater than the threshold value of 1.0,and the risk value of non-carcinogenic in children was as high as 39.3,which was much higher than adults.The results of carcinogenic risk index of As,Cr,Co,Ni and Cd showed that:the cancer risk index of children in each park is higher than adults,and the risk index of adult cancer is within the range of 10^-410^-6,there is no carcinogenic risk,however,children's cancer risk index in Renmin park,Forest park,Longyuanhu park and Diaosu park,is bigger than 10^-4,there will be a certain risk of cancer,and the Longyuanhu park is the most serious.Both adults and children,the most dangerous heavy metals that cause cancer risk is As.?5?The revised non carcinogenic risk?HQ?and the total non carcinogenic risk?HI?of heavy metals are significantly decreased before correction.The HQ before correction is 5¹8 times than after,and the non carcinogenic health risks of adults and children in the parks of Jiaozuo were less than1 and they were reduced to safety level,and the total non carcinogenic risk?HI?was 0.57 and 4.5,respectively.The carcinogenic risk index of adults and children is also significantly lower than before the correction.Although the risk index of children is still higher than that of adults,the risk index of adults and children in parks is between 10^-610^-4,and there is no carcinogenic risk.?6?Through the analysis of the sources of heavy metals in Jiaozuo city parks,the parks in Jiaozuo have been affected by mining,heavy metal smelting,burning of fossil fuels and other industrial activities and it also can be seen that the heavy metal pollution in Renmin park and Longyuanhu park is greatly affected by traffic pollution and coal-fired factors;...