Spatial Variability And Evaluation Of Soil Heavy Metals Pollution In Jiyuan Plain

Jiyuan City and its surrounding areas are selected as the study area in the paper.The content of As,Cd,Cr,Cu,Hg,Ni,Pb,Zn in this area have been investigated.Single factor index and Nemerow index have been used to evaluated the heavy metals pollution in the study area.Selecting Shibin village as the focus area,heavy metals in soil in the focus area were studied.The content of As,Cd,Cr,Cu,Hg,Ni,Pb,Zn in five layers were measured.The major pollutions As,Cd and Pb were analyzed.Fuzzy mathematics method,accumulation index and Chernoff faces diagram method were used for analysis and evaluation.In study area,soil pH ranged between 7.5 to 8.3.The content of As,Cd,Cr,Ni in deep soil were not more than soil environment standard level 2.As unevenly distributed in the region,the other three elements were evenly distributed in the region.The content of Hg,Pb,Zn does not exceed soil environment standard level 1.The content of As was in the range of 14-150 mg/kg.Cd content ranges between 0.15-70 mg/kg.Cr content was between 35-150 mg/kg.Cu content in the range of areas was between 12-170 mg/kg.Hg content in the range of areas was between 0.02157-1.347 mg/kg.Ni was distributing evenly in the area,in an amount ranging from between 10-75 mg/kg;The content of Pb was in the range between 10-2800 mg/kg.The content of Zn ranges of 25-740 mg/kg.RAccording to the type of soil environment,study area is divided into four zones by Regional Environmental Assessment,in which class I soil zone located east of the survey area,an area of 88.26 km2;Class II soil area located in the central and northern regions,an area of 256.39 km2;Class III soil area located in the northwest class district,an area of 26.67 km2 and over class III located in the north-west area of 88.21 km2,roughly surrounded by the Class III area.Single factor pollution index evaluation results show that Cd was the largest heavy metal pollution element in soil survey area.As,Zn,Cu,Hg,Ni were mainly mild pollution.Pb reached moderate pollution in more than half of the area;Cr had no pollution.Nemerow pollution index analysis showed that heavy pollution centers in Shibin Village,South Village Sili Hoon village area,its periphery and surrounding areas being mild-moderate pollution areas.Taking the serious pollution area,Shibin Village as the focus area.In the area,take samples from five layers of soil.All results from different methods of evaluation showed that the surface soil in focus area was contaminated.The soil level was evaluated as third level.Compared with environmental standard level 2,contents of Cd,As and Pb in the focus area were all overweight,among which Cd exceeded highest,reaching 20 times over standard level 2.the remaining six elements did not exceed environmental standard level 2.Compared with thebackground lower value,eight elements in study area all had varying degrees of enrichment,in which Cd was highest and Cr lowest.The three main pollution elements enriched inhe southeast corner of the lead plant,declining from the center to the surrounding.The declining trend slow in west,south because of the effect of terran.Heavy metal pollution in deep soil was relatively light.