The North China Plain (NCP), which located in arid and semi-arid areas, is a major grain-producing area in China. Due to long-term over-exploiting of groundwater for irrigation and drinking, it has formed the world's largest composite groundwater funnel, covering an area of about 72.79×103km2 accounting for more than half of the whole area. Groundwater pollution caused by human activities has become another prominent problem, it further aggravates the tension of groundwater resources in this region. Applying the evaluation method of pollution index, which is defined by (measured concentration- background concentration) / standard concentration, the comprehensive evaluation results gained by superposition of multiple single factor evaluation results show that 44.13% of the shallow groundwater have been polluted under varying degrees in NCP , among which 17.33% has been heavily polluted. For deep groundwater, 12.86% have been polluted under varying degrees, among which 0.96% has been heavily polluted. The main factors are nitrate nitrogen, arsenic, lead, carbon tetrachloride and toluene.
In order to provide evidence for the regional prevention and remediation of groundwater pollution, the division method considering four comprehensive factors of risk and extend of groundwater pollution, load of pollution source and groundwater function is established in the typical area named alluvial-proluvial fan of Hutuo River in NCP. Groundwater pollution risk is quantitatively classified by superposition of groundwater depth and recharge, medium and seepage parameter of aquifer, and lithology of the vadose zone. Extend of groundwater pollution is quantitatively classified by the extend of groundwater pollution evaluation mentioned above. The load of pollution source is quantitatively classified based on toxicity and quantity of the sources. And groundwater function is quantitatively classified based on groundwater quality and resource modulus. Divisions of groundwater pollution prevention and control in alluvial-proluvial fan of Hutuo River are obtained by superposition of these considering factors’ classifications with suitable weights. The results showed that over 70% of the typical alluvial-proluvial fan area of Hutuo River (2100 km2) is prevention and control area, and just less than 0.6% of the whole area need to consider remediation. The division results of the typical area are in line with the idea of regional groundwater pollution treatment that prevention and control is the main measure and remediation is just in view of the serious pollution area.
In this study, one sample covers a mean area of around 8-12km2, thus the data are not enough to support the remediating decision directly. In fact, the main significance of regional division is not to show decision maker where the remediation area is exactly, but indicates where we should pay attention especially while prevention needed. Further work in the view of remediation division should be supplemented before taking action.