Feasibility And Risk Assessment Study Of Wuliangsuhai Lake Sediment Agricultural Application

Lake sediment is an important part of the lakes environment,mainly includes clayminerals,organic matter and with active metal oxide. Due to the influence of element,sediment particles have large specific surface area, so it has huge effects on nutrientsubstance and migration of heavy metals. With the rapid pace of economic development,more and more persistent organic pollutants has drained off, including heavymetal,nutrient substance and nutrient substance, a considerable part of contaminantdeposit in sediment, thus the lake has polluted, water environment ecological system isunder threat. Compared comprehensively all ways of resource utilization, farmland use isthe most economical and a common way at present.Wuliangsuhai Lake as an important industry, agriculture, life recession flow site ofHeTao region, Bayannur. With the development of economy social and agricultural, a lotof return water with rich in nutrients and heavy metal is emitted into Wuliangsuhai Lake,lead to eutrophication and heavy metal pollution is increasingly serious, comprehensivetreatment of Wuliangsuhai Lake is imminent, especially in the process of sedimentdredging, cause a large number of sediment deposition in waste, existing the risk ofsecondary pollution. How to reasonable use of sediment and resource utilization is aquestion of this article. This paper according recent years to Wuliangsuhai Lake sedimentsampling analysis, Wuliangsuhai Lake sediment texture, siltation degree, stand volume,and the geochemical characteristics of the sediment are analyzed. On the basis of findingout sediment characteristics, make full use of field experiment, reveals the influence of thelake sediment on crop growth and soil environment, as well as the lake sediment offertilization on soil ecological risk assessment. The research results mainly have severalaspects:First, Wuliangsuhai Lake belongs to a typical of the shallow lakes, sediments isalkaline and sedimentation is obvious, grain composition mainly is sand and particle.Sediment volume is196.416million ton,4.19million ton per year on average. Thecontent of nitrogen、phosphorus、organic carbon and calcium are higher in WuliangsuhaiLake much higher than HeTao irrigation district. Compared with 《Control standards forpollutants in sludge from agricultural use》and parts of the European Union,the heavymetal content is below the threshold, conform to the national agricultural control standard, it has the very good farmland utilization value.Second,lake sediment is used in farmland two years，the results show that itincrease soil fertility and benefit to the crops growth. Sediment promote the growth ofthe sunflower,especially in plant height，the dispose of S4and S5has significant effects.Lake sediment promotes the production of the sonflower, the production of S5is equal tofertilization. Sediments promote the absorption of nitrogen and phosphorus, it promotesthe protein and total amino acids in kernel, but fat content is no significant change.Thirdly, sediment cause excessive nitrogen and phosphorus in the soil, it cannotpromote the content of absorbable nutrition effectively, on the contrary, it has caused therisk of environmental pollution. After the lake sediment is used, the residual heavy metalis not exceed environmental quality secondary standard for soils. The sunflower seeds’sBCF＜0.3,the trace element: Hg>Cd>Cr>Pb>As. On condition that differentapplication amount, S4(2360t/hm2·a) can used ten years in a row, S5can used five yearsin a row.Final, after the sediment of Wuliangsuhai Lake is used, on the basis of differentevaluation methods to evaluate soil ecological risk. Hg is mainly soil ecological risk’sindex, itsEirvalue is160.72, and how to resource utilization for lake sedimentscientific and safe, excess accumulation of Hg becomes the centre of attention in thefuture.