Present Situation And Evaluation Of Heavy-metal Pollution In The Surface Layer Soil Of Jilin City

With the rapid industrial development,urban pollution and the increase of agricultural chemicals types,the increasing number of soil heavy metal pollution is becoming increasingly serious.Heavy metal pollutants in soil with poor mobility, stranded in a long time and not be microbial degradation,toxic and cumulative effect of strong characteristics of the crop growth,yield and quality have a greater impact, and through the food chain affect human health,soil Once the subject of heavy metal pollution,is to eliminate an extremely easy.Therefore,investigation and evaluation of heavy metals in soil environment pollution and its risk profile,find out the soil quality of the environment,strengthen the comprehensive control of soil pollution, protection of human health is of great practical significance.This paper makes a comparatively systematic summary in characteristics,sources,and harmfulness of the soil heavy metal and the current domestic and international situation in the soil heavy metal.The soil of Jilin City is regarded as the research object in the paper.136 surface soil samples are collected.And using the statistical software SPSS,analyze pH,mineral element,the content of As,Hg,Cr,Cu,Pb,Zn,Cd in the soil, and study the variety of content of urban soil element,distribution law and geographic spatial division.With the single pollution index method,the Nemero comprehensive pollution index method and the regular fuzzy mathematics mode estimate the soil heavy metals pollution of Jilin,and draw the contaminate degree chart of each assessment factor and the soil general quality chart of Jilin based on the interpolated of software Mapgis and count different pollution grade or level area.Then,the model that appraisal for the soil environmental quality in Jilin is set up with application of software MATLAB7.6,according to Soil Environment Quality Standard(GB15618-1995),it appraises whether the soil of Jilin can reach and ensure agricultural production and safeguard the quality level of the human health.According to the result above and the spatial analysis function then probe into mainly pollution source and distribution law and put forward the corresponding prevention.From the above research,some results are achieved:1.As the promotion of the urbanization,there is trend which is rising gradually in the soil pH value of top layer of the research area,rely mainly on neutrality and alkalescence,which relates to the fact that the content of carbonate rises gradually in the soil.pH value of agricultural land in suburb is small and the soil assumes acidity, while the soil in industrial area possesses big pH value and assumes alkalescence.The main reason is that the soil in the industrial area often mixes with building offal, cement,fragment of brick and other alkaline mixture,etc.,so Ca releasing into the soil causes pH value of the soil being difference to natural soil obviously.2.According to different regions,carve up 136 pieces of soil sampling point of Jilin.According to the distribution characteristics of soil heavy metallic element in different regions,the mean seven kinds of heavy metal is Changyi Department＞Longtan Department＞Chuanying Department＞Fengman Department, mainly because the main factory of Jilin is mostly distributed in Chuanying Departmengt and Longtan Department industrial areas,influenced by industry factor, makes soil environmental quality worsen.3.The Pearson correlation analysis shows that there were strong associations among heavy metal elements in the urban topsoil in Jilin City.Relevant relations exist among the content of heavy metallic element,pH,total Fe and total Mn.The correlation coefficient of arsenic with total Fe and pH value is;the correlation coefficient of Cr with total Fe and total Mn:three kinds of elements Pb,Zn,Cd present prominent and extremely prominent relevance with total Mn and pH value.4.The topsoil has already been polluted by the heavy metal in various degrees in Jilin.However,Cd is the most dangerous pollutant to the urban topsoil.As has slight pollution only in the small area near the Employees of the University of Jilin and nearby Jilin Institute of Chemical Technology and Longtan around Reagent Factory: the area where Hg is high-load is distributed in the Longtan region of the China Petroleum of Jilin Petrochemical Company,the Urban District Changyi cotton textile factory line to the city sanitary napkins,and other rich areas of Chuanying have local pollution;Cr is mainly distributed in the north of Changyi Department and the south bank of the Songhua River;the contaminated area of Cu is mainly distributed around the Longtan wheel,Longtan mechanical plant and the Longtan hill station;the contaminated area of Pb is mainly distributed in Jiangbei Chemical Factory and near the main streets and squares.5.According to the degree of pollution of seven kinds of heavy metal of topsoil in Jilin,the order is:Cd＞Hg＞Cr＞Zn＞Pb＞Cu＞As;from the administrative area, seriously polluted in proper order:Changyi Department＞Longtan Department＞Chuanying Department＞Fengman Department;from geographical distribution,urban area＞suburb,north＞south of urban area.6.According to Environmental Quality Standards in Soils,the Jilin soil environment quality is appraised.Generally speaking,the overall quality of soil environment is satisfying,of which 70.04%of the sample unit meets the ClassⅠnational soil environmental quality standards,basically keeps the natural level,and does not threaten agricultural production and human health.7.The Factor Analysis showed that the sources of different heavy metals in urban topsoil of Jilin City.Cu,Pb,and Zn mainly originated from traffic contamination;As was still mainly controlled by natural factors,originated from natural sources;coal-fired was the main source of Hg;Cr and Cd mainly originated from the industrial and chemical fertilizer.