Evaluation Of Heavy Metals Pollution Characteristics In Sediment And Environmental Risk Of Sediment With Landfill Disposal In Shandong Peninsula

For a long time,industrial"three wastes"have had a negative impact on almost environment in China.Surface water was one of the pollutant acceptors.After the heavy metal pollutants enter the water body,most of the heavy metals will gradually transfer to the sediment and enrich in the sediment.The accumulation of heavy metals in river sediment in mining and smelting areas was more serious.Therefore,this study taked the sediment polluted by heavy metals in gold mining area as the research object,and carried out two aspects of research work:1)investigating the spatial distribution and forms of heavy metals in the Jiehe river of gold mining area,tracing the source of heavy metals enriched in sediment,and using various evaluation methods to carry out risk assessment of heavy metals,to comprehensively understand the characteristics of heavy metals pollution in river sediment of gold mining area;2)Aiming at two kinds of treatment and disposal technologies of sediment contaminated by heavy metals widely used in engineering,i.e.geotechnical bag landfill technology and highly efficient dewatering landfill technology,the environmental friendliness of sediment in disposal site was ensured,the environmental hazards of sediment treated by two kinds of projects were tracked and analyzed,the stability of heavy metals in sediment was revealed.The main conclusions are as follows:1)Characteristics of heavy metal pollution in the sediment of Jiehe River:As,Cd and Hg contents in the sediment of Jiehe River exceeded the background values of Chinese river sediments by 622.2,329.8 and 16.5 times,respectively.The variability of heavy metals in sediments was very high in spatial distribution.The potential ecological risks of Hg,Cd,As and Cu were at the highest level and posed a great threat to organisms.According to the results of health risk assessment,the non-carcinogenic health risk index of seven heavy metals?Cr,As,Cd,Hg,Pb,Cu and Zn?was less than 1,which indicated that the health risk of heavy metals in the sediment of Jiehe River can be neglected.The results of source analysis showed that the accumulation of heavy metals in sediments mainly came from gold mining,metal smelting and agricultural activities.2)Assessing the environmental risk of heavy metals in surface soil of two landfill disposal sites:Determining of heavy metals contents and forms in surface soil of geobag national dewatering landfill site and high-efficiency dewatering landfill site,and three environmental risk assessment methods,I_geo,RSP and human health risk assessment were used respectively.The results showed that the bio-availability percentage of Cd in surface soil of geobag natural dewatering landfill site was high.In addition,the non-carcinogenic health exposure of As to nearby residents should not be neglected;As in surface soil of high-efficiency dewatering landfill site had certain health risks to children,so it is necessary to guard against the exposure risk of the site soil to children.3)Evaluating the safety of sediment after three years of landfill with two kinds of sediment treatment technologies:Based on the amount of heavy metals in sediment,distribution characteristics of metal forms,leaching toxicity test and RAC,PERI evaluation results,it was concluded that the safety of sediment treated by geo-bags natural dewatering treatment was high,and there was no ecological risk of polluting local groundwater;the environmental hazard of heavy metals in sediment treating by high-efficiency dewatering treatment was low and the environmental influence ability was limited,but attention should be paid to the possible risk of Ni infiltration.The production of industrial pollutants over the past decades has resulted in serious accumulation of heavy metals in river sediments,which was extremely serious ecological harm.After sediment contaminated by heavy metal was treated by heterotopic solidification and stabilization landfill,the bioavailability of heavy metals was reduced,the ecological risk was changed to weaken,and the migration possibility and transfer ability could be reduced.In addition,the health risk of heavy metals in landfill site should not be neglected,and it is necessary to ensure the cleanliness and safety of overburden soil in landfill site.