ABSTRACT
Groundwater is the main source for water use in the North China Plain. However, based on the monitoring data, nitrogen pollution in groundwater is common in groundwater in the North China Plain because of intensified agricultural and industrial activities. Using the monitoring data of wells and a coupled surface water and groundwater numerical model, we try to identify the origin of nitrogen pollutant in the groundwater in the region. First, based on the 10-year monitoring data of over 200 wells, it was found that the groundwater quality at 30% wells were worse than Class III of the National Groundwater Quality Standard, and the main pollutant items were nitrogen and heavy metal, unsuitable for drinking. Second, Integrated Groundwater Environment Simulation Framework (IGESF) was developed and validated by coupling the groundwater reactive transport model (MT3DMS) and the distributed watershed model (WEP-L). Third, the application results of IGESF showed that during the 10 years from 1995 to 2004, annual average nitrogen pollutant loaded from non-point agricultural sources into the aquifer is about 38,400 t, and annual average nitrogen pollutant loaded from the polluted river water into the aquifer is about 26,0001 t, with the former larger than the latter. Moreover,it was found that the nitrogen loaded into aquifer is related to the sum of precipitation and irrigation water, and the agricultural fertilization, with an correlation coefficient larger than 0.6
