Spatial Distribution Characteristics And Pollution Risk Assessment Of Soil Heavy Metals In A Municipality Of Yunnan Province

Soil is the basic element and important resource for human survival.In recent years,due to a large number of artificial and natural factors,a large amount of heavy metals are enriched in the soil,causing the soil quality to decline and being gradually enriched through the food chain,directly jeopardizing people’s health.This paper takes the agricultural land soil of a city in Yunnan Province as the research object,and analyzes 8soil heavy metals(Pb,Ni,Cd,Hg,As,Cu,Cr,Zn)through geostatistics basis,GIS technology and routine detection and analysis methods.The spatial distribution characteristics and correlation of three chemical properties(pH,SOM,CEC),then evaluated the pollution status and potential ecological risk of heavy metals in eight soils in the study area.The main research conclusions are:(1)The soil pH,organic matter and cation exchange capacity of this city’s soil were moderately varied.The soil pH average was 6.519,which was weakly acidic.The soil in the area was relatively fertile,and the organic matter content was generally in the second-class high level.The soil cation exchange capacity was between 5.4-52.5 cmol(+).The basic physical and chemical properties of the soil all showed moderate spatial autocorrelation,resulting in a higher degree of spatial variability.(2)Spatial interpolation results showed that the soil pH value of the city was lower than those of the higher latitude,and the soil organic matter content was significantly different.The soil cation exchange capacity(CEC)was higher in the northeast and lower in the southwest.(3)The overall manifestation of eight heavy metal pollution in the city was: the pollution of As,Cd,and Pb were heavy,Cu was relatively light,and three heavy metals,Cr,Zn,and Ni,appeared to be clean(safe)or clean enough(alert).(4)The potential ecological risks of Cd and Hg in this city were relatively high,and As also showed potential ecological risks at some sampling points.The comprehensive ecological risk index of heavy metal multi-element indicated a slight potential ecological risk.The potential risk of agricultural land in this city was not high,and there was noserious pollution area.Plant restoration and microbial restoration could be used to manage contaminated soil.As a heavily exploited mineral zone,reasonable management measures should be taken to ensure stable growth of production and sustainable development of the environment.(5)There was a significant positive correlation between pH and Cr and Zn(P<0.05),and a extremely significant positive correlation with Ni(P<0.01)in soil.There was no significant correlation between soil organic matter and heavy metal content(P>0.05).There was a significant positive correlation between soil cation and Zn(P<0.05),and a extremely significant positive correlation with Cu and Ni(P<0.01).There was a significant negative correlation between pH and Pb and Ni single pollution index and potential ecological risk factors of Pb,Cu and Ni(P<0.01).Soil organic matter only showed a significant positive correlation with Pb’s single pollution index and potential ecological risk coefficient(P<0.05).There was no significant correlation between cation exchange capacity and single pollution index and potential ecological risk index(P<0.05).