| In recent years,with the global economy development and industrialization,soil pollution from industry receive more and more attention,and the content of heavy metal in soil-crops system was significantly influenced by waste water,the waste gas and the waste residue from factories.A case study area near an abandoned smeltery in paddy field with an area about 12.1km2 was selected in the south jiangsu province,P.R.China.113 surface soil samples,113 brown rice samples and 32 depth soil samples in the core research region were collected by the sampling method of grid(about 300～400m) and increase the density in the core area.The analyzed items including,soil pH,organic matter,available and total heavy metals in soil,heavy metals in brown rice.In this article spatial variation and the characteristics of accumulation and transfer of heavy metal pollution were researched by use of GIS method and Geostatistical analysis.Simultaneously,3 monitor cross sections (each cross section collected 5 sample points which to be apart from roadbed different distance) were arranged to discuss the road influence to the soil heavy metal spatial distribution in typical area.The result showed that the surface soil is partially contaminated by Cu and Pb but heavily contaminated by Cd.The concentration of total Cu was between 21.7 to 145.9 mg·kg-1,and about 21.2%of which was above the environmental threshold and polluted;the total Pb's concentration was between19.5 to 459.0 mg·kg-1,only about 3.5%of sample above the environmental threshold;the Cd's concentration was between 0.69 to 27.8mg·kg-1, all was above the environmental threshold and polluted,in the study area the mean value concentration of available Cu,Pb and Cd is 13.0 mg·kg-1,10.7mgkg-1 and 0.72 mg·kg-1 respectively which concluded that the content of Pb and Cd is relatively high and more risk.In brown rice the concentration of Pb and Cd was between 0.04 to 5.8 mg·kg-1 and 0.003 to 27.4 mg·kg-1,with an average of 0.59 mg·kg-1 and 0.20 mg·kg-1 respectively.The Cu's concentration was between 0.3 to 15.5mg·kg-1 with an average of 2.0 mg·kg-1.There was 36.3%of Pb contents and 27.4%of Cd contents in the brown rice above the national threshold of food quality and only 1.8%of Cu was above this standard.It is indicated that the risk of safely use of soil in the study area is worth paying attention.According to the result of geostatistical analysis,in the surface layer,the nugget-to-sill ratio showed a poor spatial dependence for soil total Cu and available Cu which considered that its variational levels are mainly attribute to anthropogenic activities and a moderate spatial dependence for other properties which anthropogenic activities and non-anthropogenic activities are all considered to be important to their variation.The directional variation of soil total or available Cu,Pb and Cd are all from southeast to northwest which were inconsistent of pH and organic material but more similar to brown rice Cu,Pb and Cd.The ordinary cokriging interpolation of soil Cu with Pb contents and Cu with Cd contents(the correlation coefficient between predicted and measured value are respectively 0.687 and 0.711) was more precise than the ordinary kriging interpolation(R=0.675) of soil Cu content.The ordinary cokriging interpolation of soil total Pb and total Cd also have the same conclusion.It conclude that the element of Cu,Pb and Cd shows a higher spatial correlation.Besides the ordinary cokriging interpolation of soil total Pb content with organic matter,the precision of soil total Cu and total Cd contents with organic matter are also improves,but various heavy metals with pH have the varying degree drop.It shows that the content of Cu and Cd have a high spatial correlation with organic matter,but the content of Pb and organic matter or the content of Cu,Pb,Cd and the pH have a lower spatial correlation.The same research are also in the available Cu,Pb and Cd,result indicated that among the content of available soil heavy metal Cu,Pb,Cd also have the very strong spatial relevance.Besides the content of Pb,other element of heavy metal have a significant spatial correlation with pH.All of available heavy metal content have the high spatial correlation with organic matter.It explained that the available soil heavy metal are easier than total soil heavy metal to be influenced by pH and organic matter.According to the result of the ordinary cokriging,there was a good spatial correlation among of Cu,Pb and Cd contents in brown rice and surface soils(regardless of total and available),but the correlation was higher between Cu and Cd contents in available soil heavy metal and brown rice than that the total soil heavy metal,the method based on the geostatistical module in ArcGIS can exactly predict the spatial variation of heavy metal pollution in typicall region. Enrichment coefficients and downward migration tendency in key research area indicated that Cu,Cd compare Pb more easily absorption by rice and move down to the deeper layer.There are signifant exponential or linear function relationships between the content of surface soil heavy metal and brown rice heavy metal.in research area.There were significant relationship between Cu and Pb in rice and soil,but linear relationship between Cd in rice and soil.For rice absorbed Cu and Pb from soil,the critical concentrations for available and total Cu were 10 mg·kg-1 and 100 mg·kg-1 respectively,and the critical concentrations for available and total Pb were 15 mg·kg-1 and 150 mg·kg-1respectively, according to the relationship.When rice Cu is at 10 mg·kg-1 according the Maximum Allowable Safety Levels of Cu in Foods(GB 2762-2005),critical concentrations of available Cu and total Cu in soil are at 24.0 mg·kg-1 and 198 mg·kg-1,respectively according to the relationship.When rice Pb is at 0.2 mg·kg-1(GB 2762-2005),critical concentrations of available Pb and total Pb in soil are at 10.8 mg·kg-1 and 76.4 mg·kg-1, respectively according to the relationship.According the Maximum Allowable Safety Levels of Cd,the critical content is quite high,the available and total Cd are about 0.71mg·kg-1 and 4.15 mg·kg-1 respectively according to the relationship.This is possibly because partial high content of cadmium area used the lime as soil modifier,which enhanced soil pH and reduced the Cd activity in the research areaTo road's three monitor cross section,only then the third cross section can accurately reflected the road influence for heavy metal content in soil-rice system.The road influence for heavy metal content displays that,to approach the highway department the content to be high and reduces rapidly when the distance to the road increased.The content of soil heavy metal Pb was most serious affected by road and the influence region amounts to 200 meters,next is the Cd pollution scope amounts to 50 meters,finally is Cu.the same results was Obtains in the brown rice.
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