[Comparison and Analysis of the Quantitative Methods for Pollutant Sources Load in Groundwater Contamination Risk Assessment].

Groundwater contamination risk assessment is an important basis for the protection of groundwater resources and the prevention and control of groundwater pollution. Its evaluation system is usually composed of three elements, which is vulnerability, pollutant source load and groundwater value. The pollutant source load plays an important role in risk assessment. Because of the difference among methods for pollutant sources load quantification, there will inevitably be different demand for the basic information survey on pollutant sources, as well as unknown impact on the final assessment results. In order to explore the impact of quantitative methods for pollutant sources load on groundwater contamination risk assessment, a case study was conducted in the mesoscale region of alluvial fan in Hutuo River, China. The two representative methods of grading index and quantitative index assessment systems were applied to quantify the pollutant sources load, in combination with the same vulnerability and groundwater value. The results constructed from different risk assessment systems were compared. The results showed that there were great differences between the two methods of quantification for pollutant sources load, and the result of contamination risk assessment also revealed significant differences in the feature of risk valve and the spatial distribution of the risk levels. The results of contamination risk assessment were strongly influenced by the choice of quantification for pollutant sources load methods. The grading index method was suitable for large scale region with lower precision of basic information and was simple, and the results of assessment had relatively lower reliability. The quantitative index method was suitable for the mesoscale and micro-scale region with higher precision of basic information and was relatively complicated, and the results of assessment had relatively higher reliability. It was shown that the scale effect of evaluation region had an important influence on the choice of methods.