Groundwater Environmental Impact Assessment Of Shenghong Polysilicon Project In Henan

Taking the Shenghong polysilicon project in Henan for example, through theinvestigation the hydrogeology, environmental geology, current groundwater exploitationsituation, the supply water source and all kinds of pollution source of the proposed project siteand its surrounding and downstream, there is a pollution risk of groundwater caused by theproject. For protecting groundwater resources and preventing and controlling of groundwaterpollution, a series of work were carried out. There are the following conclusions.(1) Using standard index method to evaluate present situation of groundwaterenvironment quality, the shallow groundwater in assessment area is bad. There are totalhardness, total dissoloved solids, ammonia nitrogen, nitrate, nitrite, sulfate, chloride, fluoride,colority, turbidity exceeding the standards of groundwater quality, which may have somethingto do with the depth and surrounding environment of the wells.(2) Using fuzzy matter-element analysis method to calculate the assessment area waterquality, most areas are Ⅴ class or Ⅳ class,and few areas are Ⅱ class or Ⅲ class;but usingthe F value evaluation method, all areas are Ⅴ class or Ⅳ class. The result of the groundwatercomprehensive evaluation, using the fuzzy matter-element analysis method, is superior tousing the F value evaluation method. Because F value evaluation method gives priority to themost serious pollution factor, then fuzzy matter-element analysis method gives fullconsideration to the boundary transition of the water quality classification, and it takes intoaccount the different weights of evaluation factor’s influence on the groundwater quality, itsresults is more accurate.(3) Static adsorption experiment results show that the Cl-and F-both are negativeadsorption phenomenon, namely under the static condition, soil samples not only adsorb Cl- and F-, but also dissolve a small amount of pollutants; But soil samples have certain capacityto adsorb NO3-, so the soil adsorption has certain blocking ability to NO3-.But the leaching test results and the static adsorption experiment results are different.Under the two working conditions of leaching test, the soil samples are weak to adsorb Cl-,and strong to NO3-and F-. Maybe due to the limited capacity of the soil sample, theadsorption quantity of the high concentration of NO3-reduces over time.Leaching test is better barrier to pollutants in shallow soil than static adsorptionexperiment.(4) By predicting contaminants (including Cl-, NO3-and F-) migration in shallow aquiferof the planed factory using the numerical method with the aid of modflow software, showsthat in the case of no impermeable layer, whether the normal conditions or the abnormalconditions, in20years each kind of influence factor will impact on groundwater2000mdownstream of the planned factory seriously, causing local groundwater quality beyond Ⅲwater quality standards.