Pollution Evaluation And Three-dimensional Spatial Distribution Of Heavy Metal In A Certain Arsenic Smeltery Site

Lots of heavy metal pollution sites have emerged because of enterprises stopped production and relocated.These sites have high concentrations of pollutants which hidden and remain in the soil for a long time,posing a threat to the growth of surrounding crops and human health.It is important to understand pollution factor and pollution degree and pollution space distribution by analyzing this heavy metal in the soil of site,which is the basis for soil pollution restoration and safe development reuse of site.The evaluation object in this paper is a historical site of arsenic smelting plant in Hunan province.After site investigation and geological exploration to obtain site geology,borehole and soil sample data.The pollution degree and the spatial distribution characteristics of main pollution factors of heavy metals(Cu,Pb,Cd,As,Hg,Sb)in soil samples were analyzed by fuzzy comprehensive evaluation method and SKUA-GOCAD software.The conclusions are as follows:(1)The soil heavy metal pollution in arsenic smelting plant was analyzed by fuzzy comprehensive evaluation method.Aiming at the weight,the entropy weight method was used to establish the relationship between various heavy metal evaluation factors,and the fuzzy comprehensive evaluation method was improved by combining the superscalar multiple of heavy metal concentration and heavy metal toxicity.The compound weight of heavy metal concentration overbid multiple,heavy metal toxicity and entropy weight method was established.The relationship between various metals was established,and the soil pollution was evaluated comprehensively by using the concentration of heavy metal evaluation factor and the toxicity information of the heavy metal compound pollution site,and good evaluation results were obtained.(2)According to the result of the improved compound weight fuzzy comprehensive assessment method,36 soil samples were evaluated that 6were assessed as level 1(still clean),1 as level 2(mildly polluted)and 29as level 3(severely polluted).The pollution degree of deep soil is higher than that of surface soil,among them,the first level is the surface soil,and the pollution degree is relatively light,while the deep soil samples are all the third level,and the pollution degree is relatively serious,the main heavy metal pollution factors in the soil are As,Pb and Sb,and the pollution factor with the largest contribution rate is As.The overall soil environment quality of the site is poor,which needs to be repaired and treated.(3)Based on skua-gocad,a three-dimensional geological model of the site was established with geological exploration data and formation information.The anisotropic 3d variogram of the major pollution factors(As,Pb,Sb)was established by using the spatial attribute and concentration information of heavy metals,and the 3d variogram and the3d kriging interpolation method were used to conduct 3d spatial analysis of the major heavy metal pollution factors in the soil based on the 3d geological body.The results show that the earthwork of the site is about26726m~3,among which the earthwork of the artificial fill layer is about12942m~3,and the earthwork of the clay layer is about 13784m~3.Within the space of the site,the concentration of As is higher in the north than south and higher in the deep layer than surface layer.The maximum concentration area was used as a smelting waste residue stacking area and waste water treatment area,and both artificial fill and clay layers were polluted by As.The As concentration of the deep soil is relatively high until the sandstone layer at the bottom.The Pb concentration area is mainly distributed in the eastern and southern regions of the site,and the concentration value decreased from shallow to deep.The maximum concentration area was used as the former smelter raw material stacking area and smelting area.In the living and office areas,there is an abnormal area of high concentration in the medium-depth soil.Pb pollution area is concentrated in the artificial fill.Sb concentration area is mainly distributed in the smelting area in the south of the site,and the concentration value decreases from shallow to deep.The pollution is mainly concentrated in the artificial fill.