Pollution Analysis And Health Risk Assessment Of Heavy Metals In Soil-crop Systems: Case Study Of A Typical Agricultural Area In Zhuangmu Town, Changfeng County

In order to investigate the heavy metals in the soil-crop system in farmlandsof Zhuangmu town，we located162sampling points in10different villages andcollected wheat, canola and vegetable samples and their respective soil samples.Based on the analysis of the content of Cr, Cu, Pb, Zn and As in the soils and crops,we analyzed the heavy metals in the soil-crop system about their distribution,pollution degree, heavy metals relevance, and the pollution source of soil heavymetals. Further we evaluated the potential ecological risks of soil heavy metals andthe health risks of crop heavy metals. The main contents and results were asfollows:(1) The average contents of Cu, Pb, Zn and As in the study area were1.20,1.46,1.64and1.44times larger than the standard background values in Anhui Province,respectively. The result of Kriging spatial interpolation showed that the contents ofCu and Pb gradually increased from east to west, and regions with high contents ofCr, Zn and As in Zhuangmu Town presentd spotty distribution.(2) According to the results of their Nemerow indexes, the order of soilcontamination degree of heavy metals was Pb> Cr> Cu> Zn> As, and thepollution level of Cu, Pb, Zn and As was slight; the order of soil contaminationdegree of the10villages was Zhuangmu> Liuqian> Jinqiao> Zhangwei>Yangwan> Xueqiao> Houji> Zaolin> Lizhuang> Xugang; vegetables wereheavily polluted by Pb, moderately polluted by Cr, and non-polluted by Cu, Zn, As,and the order of the10crops was wheat> rape> coriander> amaranth> cabbage>leek> onion> chive> bean> garlic.(3) Multi-variety statistical analysis results showed that there was a partialcorrelation between crops and the relative soil heavy metals, in which chive hadthe strongest partial correlation with the heavy metals; some heavy metals in wheat,rape, amaranth, chive, bean and garlic had linear relationships with the heavymetals in soil under significant level. The principal component analysis of heavymetals in the farmland soil showed that there were3principal components, the firstcomponent was TN, TP and OM, the second was Cu and Pb, and the third componentincluded As and Zn. All of the three parts were greatly affected by humanactivities.(4) Based on the interval-number theory, we made the potential ecological riskevaluation of the heavy metals in soil of different places. The results showed that Yangwan and Zhangwei were in high risk level, others were all in medium risklevel. We also evaluated the risk based on trapezoidal fuzzy number theory,indicating that the total risk R Iof the heavy metals with expectation interval of[16.65,53.96], was in medium risk level, in which As was in medium risk leveland Cr, Cu, Pb and Zn were in slight risk level.(5) The health risk evaluation of the heavy metals in crop was made on the basisof the blind number theory. The results suggested that the orders of the health riskof the intake by adults and by children were both Pb> Cr> Cu> Zn> As, in whichPb and Cr could cause chronic and toxic risk effects on adults and children. Thehealth risk values TTHQ for adults and children intake were4.30and9.55,respectively, indicating that long-term consumption of the vegetables in study areamight bring negative effects on people’s health.