Assessment And Prediction Of Heavy Metals In Urban Soils Of Poyang Lake Eco-economical District Based On Geostatistics Methods

Poyang Lake Eco-economical District,as a central important economic development group in Jiangxi Province,contains a large number of industrial and agricultural enterprises.Fertilizers with heavy metals used in agricultural producing processes and wasted pollutants with heavy metals emitted by industrial enterprises can get into the soil environment through atmospheric deposition and substances exchange between soil and water,therefore raise the content of heavy metals in soils.Soil environment is closely related to the food chains and human lives,the heavy-metals content in the soil of main urban area in Poyang Lake Eco-economical Distrct is taken as the research focus to explore the pollution distribution of heavy metals in soil.Then to make reasonable assessment of soil heavy-metal pollution as to provide theoretical support for the study of sustainable development of human society in this region.72 soil samples from Poyang Lake Eco-economical District with large population density were collected,and the contents of eight heavy-metal elements,such as Cu,Zn,Pb,Cd,Cr,Ni,Hg,As,were determined in the national standard method.Geographical interpolation analysis of heavy-metal's distribution was carried out with geostatistical knowledge by using ArcGIS software.Various methods of pollution assessment and hazard assessment were used to assess the risk of pollution.The conclusions of the study are as follows:(1)All elements exceeded the standards in different samples.The contents of Cu,Pb and Ni were relatively high in the soils of Nanchang research area,the contents of Cu and Pb were relatively high in Yingtan research area,the contents of Zn,Cd and Hg were relatively high in the soils of Jing Dezhen research area,the contents of Zn,Cr,Ni and Hg were relatively high in the soil of Jiujiang research area.The sludge from the four municipal sewage treatment plants were relatively high,showing similar distribution law to that in soils.8 heavy metals can be divided into three categories based on their souces:traffic source(Cu,As,Pb),industrial source(Cd,Hg)and agricultural source(Cr,Ni,Zn).The influencing factors,TOC and pH,have certain effects on Hg,Zn and Cu respectively.By adjusting pH and TOC content in soils,Hg and Cu can be controlled in some degree.(2)Kriging pollution interpolation analysis of heavy metals showed the pollution of heavy metals in Nanchang city is concentrated in the north;the main pollution in the east of Yingtan researching area is from Cu,Zn and Hg,while the main pollution in the west is from Pb,and the main pollution in the south is from Cd and As;the pollution of Cu in Jing Dezhen researching area is higher in some bording areas,and the main pollution in the southwest is from Zn,Ni and Hg;The main elements in the southwest of Jiujiang researching areas are Cu and Hg,and Pb in northwest,Ni and As in the northeast,Zn in the middle,Cd in the north and Cr in the East.(3)Single factor index,Muller index and single factor ecological risk index all indicated that the pollution of Cd is relatively heavy,while the pollution of Zn and Cr are relatively light.Nemerow index and comprehensive ecological risk index all indicated that Yingtan city is relatively heaviest polluted.Focusing on Cd and heavy metal pollution in Yingtan soil can effectively improve soil environmental quality in Poyang Lake Eco-economical District.(4)Human health risk assessment showed that non-carcinogenic health risk and carcinogenic risk of Cd,Cr,Ni and As were highest through oral intake,followed by skin contact intake,respiratory intake results the lowest comprehensive health risk,and children were more susceptible to non-carcinogenic and carcinogenic risk of heavy metals than adults.(5)The pollution prediction results of Cu and As in Nanchang City show that under optimistic conditions,the pollution of two heavy metals in 2029 will be lighter than that in 2014;without mutation,the pollution of two heavy metals in 2029 will be slightly higher than that in 2014;under pessimistic circumstances,the pollution of two heavy metals in 2029 will be significantly higher than that in 2014.