Study On Risk Assessment Method Of Groundwater Pollution In A Certain Area Of Northeast Beijing

The groundwater environment is complex and the pollution is hidden,which poses a great threat to people’s health and social and economic development.In this paper,the plain area in the northeast of Beijing is taken as the study area,and the groundwater pollution risk assessment model is established with three subsystems:groundwater function value,hazard and migration flux.The distribution characteristics in the area are explored respectively,and finally the study area is divided into five risk levels: low pollution risk,low pollution risk,medium pollution risk,high pollution risk and high pollution risk.The main achievements of this paper are as follows:(1)The groundwater in the study area has been polluted to some extent.Among the 141 points,there are 115 points with Class IV water or above,and the proportion of points exceeding the standard is as high as 81.56%.There are 14 single items exceeding the standard in groundwater samples,of which nitrate pollution is the main one.On the whole,the water quality in the southwest of the study area is relatively good.(2)The functional value of groundwater in the study area is at a medium level as a whole,and it decreases from north to south.The main factors affecting the regional functional value are groundwater level and groundwater quality.(3)The overall migration flux in the study area is at a medium to high level,and the areas with high migration flux are concentrated in the central and northwest regions.The main factors affecting the migration flux of pollutants are groundwater depth and migration rate.(4)The harmfulness of pollution sources in the study area is at a low level as a whole,among which the areas with high harmfulness are scattered,and the main factors affecting regional harmfulness are industrial sources,landfill facilities and domestic sources.(5)The risk of groundwater pollution in the study area is generally at a moderate to low level.The areas with high risk of groundwater pollution tend to be concentrated in some areas and scattered in other areas.The areas with low risk of groundwater pollution are mainly distributed in the marginal areas in the south and north of the study area.