Nitrogen species distribution in groundwater of the Haihe River Plain

Natural and anthropogenic nitrate (NO3-N), nitrite (NO2-N) and ammonia (NH4-N) in groundwater represents vital environmental and health concern issue globally. Here, we present data and discuss sources of nitrogen compounds in the groundwater that accounts for two-thirds of the total water supply of the Haihe River Plain with a population of over 100 million. The spatial and temporal distribution of the nitrogen compounds (NO3-N, NO2-N, NH4-N) in the groundwater are linked to a variety of sources, such as fertilizers, domestic sewages, industrial wastewater and precipitation. About 12.64%, 53.90% and 16.73% of the investigated groundwater wells in the Haihe River Plain have NO3-N, NO2-N and NH4-N concentrations above permissible values for drinking water, respectively. Comprehensive actions such as changing farming methods, applying fertilizer at suitable times and appropriate irrigation pattern for the Haihe River Plain are required to reduce the nitrogen pollution in the future.