Identification Method Of Main Pollutants In Groundwater Based On Groundwater Contamination Assessment

Identifying the main pollutants in groundwater has great importance on prevention and control of groundwater contamination.This paper has summarized the identifying systems foreign and in-country for the past few years,tried to construct a method based on groundwater contamination assessment aimed at the disadvantage of the existing methods taking the case of Lanzhou.On this basis,this method was used to complete the screening of main pollutants in groundwater,traditional method based on groundwater contamination risk assessment was used to identify main pollutants at the same time.Then comparison and analysis was made to verify the rationality and feasibility of the system based on groundwater contamination assessment.The main conclusions are as follows:(1)A method based on groundwater contamination assessment was constructed to screen the main pollutants.The selected component was divided into natural component and artificial component,the degree of contamination was qualified by background value and the detection limit respectively,the mean value and median value of the contamination and the toxicity parameters of each component was chosen as index to calculate the score of each component by factor multiplication method and grading scoring method.Finally sorted the component by score as the ranking of major pollutants.(2)The factor multiplication method calculate the score according to the actual value,the method is taking full account of the differences between the factors and there is no human factors in the calculation process.But this method does not apply to this situation when the internal parameters of each factor is very different or there are correlations among the factors.Fractional scoring method can effectively solve the impact of the internal parameters of a single factor on the impact of the results.But there are human factors in the weight setting.(3)The comparison of the method based on groundwater contamination assessment and the method based on groundwater contamination risk assessment come to the conclusion that the ranking result of the method based on groundwater contamination assessment is comparatively rational.This method applies to study area with low accuracy and when the study area is lack of pollution source information and hydrogeology data,but there are abundant groundwater monitoring data.(4)The main pollutants screening in groundwater for the study area show that the top fifteen pollutants are mainly heavy metals and organic matters,followed by: benzene,hexachlorobenzene,Sb,1,2-dichloroethane,dichloromethane,As,carbon tetrachloride,benzo(b)fluoranthene,Cd,benzo(a)pyrene,pentachlorophenol,Class,vinyl chloride,Co,Ni.