Pollution Assessment And Source Apportionment Of Heavy Metals In Soil Of Handan City

The soil of Handan city is facing the threat of industrial "three wastes",automobile exhaust emissions,fuel leakage,tire wear,chemical fertilizer and pesticide emissions of heavy metal pollutants.It is of great significance to carry out the research on soil heavy metals and to analyze the source of heavy metal pollution.The pollution level of heavy metals in soil,ecological risk and health risk level were evaluated.According to the results of heavy metal pollution assessment and source analysis,effective measures were taken to reduce the pollution level of heavy metals in soil.In this study,64 soil samples were collected by five point sampling method in Handan city.The contents of Cr,Mn,Ni,Cu,Zn,Cd and Pb in the samples were determined by inductively coupled plasma-mass spectroscopy(ICP-MS).The average contents were 94.40 mg/kg,588.25 mg/kg,47.47 mg/kg,43.16 mg/kg,158.32 mg/kg,0.92 mg/kg and 33.27 mg/kg,respectively.Except for Mn,the average contents of Cr,Ni,Cu,Zn,Cd and Pb all exceeded the soil background values of Hebei Province,especially the pollution of Cd,which was approximate 10 times of the soil background value.The spatial distribution map of soil heavy metal content in the study area was made by using Arc GIS software,and the source of heavy metal was preliminarily identified by analyzing the spatial distribution of heavy metal.The results show that the spatial distribution of Cr and Ni is similar.The high content is located in the middle and northeast of the study area,while the low content is in the southwest.They have similar pollution sources.The spatial variation trend of Mn,Zn and Cd content is similar,and the high content is concentrated around the industrial area in the west of the study area.The heavy metal pollution in this area is caused by industrial activities.The contents of Cu and Pb are also higher near the road with higher vehicle density,which is caused by traffic activities.Each year,2414.88 kg,17877.60 kg,1347.84 kg,1759.68 kg,15556.32 kg,93.60 kg and 3182.40 kg of Cr,Mn,Ni,Cu,Zn,Cd and Pb were input into the soil of the study area.Correlation analysis,cluster analysis and PCA were used to identify soil heavy metal pollution sources.PMF model was used to identify pollution sources and analyze the contribution of pollution sources.Through the source identification,it is found that the heavy metal content in the soil of the study area was mainly affected by three pollution sources,namely the traffic source with Cu,Pb and Cd as the main load elements,the natural source with Cr and Ni as the main load elements,and the industrial source with Mn and Zn as the main load elements.PMF model analysis showed that the contribution of traffic source,natural source and industrial source was 17.61%,28.62%and 53.77% respectively.The result of source identification is consistent with that of PMF model.Through the assessment of heavy metal pollution level in Handan City,it is found that the pollution level of Cd in the study area was the most serious,and the study area was also polluted by Cr,Cu,Ni,Pb and Zn in different degrees,while Mn was in the no pollution level.The pollution load index of the whole study area was 1.70,which was in the medium pollution level.The average value of Nemero comprehensive pollution index was 7.23,which was in the heavy pollution level.The risk assessment of soil heavy metals in the study area was carried out,and its impact on the ecological environment and human health was studied.The results showed that the ecological risk of Cr,Mn,Ni,Pb and Zn in the study area was low.The risk of Cu in most sampling sites was at low ecological risk,only 5% of the samples were at moderate risk.Cd in83% of sampling points was above high ecological risk level,which posed a serious threat to the ecosystem of Handan city.Heavy metals were harmful to public health mainly through ingestion,and the risk of children was higher than that of adults.Cr had the highest non-carcinogenic risk(HI < 1),followed by Mn,Pb,Ni,Cd,Cu and Zn.The non-carcinogenic risk of these seven heavy metals could be ignored.Pb had no significant carcinogenic risk to children and adults.Cd,Cr and Ni had acceptable or tolerable carcinogenic risk to children and adults.This study is of great significance to understand the spatial distribution,pollution status,ecological risk,health risk and main pollution sources of heavy metals in Handan city.According to the results of pollution source analysis,the use of low Cd coal,fuel oil and tires should be popularized.Controlling the discharge of industrial pollutants is conducive to the control of soil heavy metal pollution.