Current situation and causal analysis of groundwater nitrate nitrogen content in the regions surrounding Bohai Sea in Hebei province

With investigation in field and assay in the lab, the current situation and influencing factors of groundwater nitrate nitrogen (hereinafter referred to as NO₃^- - N) content in the regions surrounding Bohai Sea in Hebei province were studied. The results show that the contents of groundwater NO₃^- - N in the regions generally meet the level III criterion of GB/T14848-93. However, the spatial variability in the region is great. In Qinhuangdao, the situation is the severest with the average value of groundwater NO₃^- - N increasing year after year from 2005 to 2007 as 4.73 mg/L, 10.38 mg/L, and 11.26 mg/L respectively. The averages of the last two years surpass the drinking water criteria (<;10mg/L) made by WHO. Among the influencing factors, various types of farmland affect the content most. The ranking is: cropland >; vegetable land >; rice plus fish-raising land >; orchard. The water samples with the highest content are mainly from spring corn farmland. The hill in the type of physiognomy affected greatly the content of NO₃^- - N in groundwater. The content reduces sharply with the continuous decrease of groundwater depth. Fertilization, surface run-off, and aquatic product pollution are the main causes of formation for the increase of groundwater NO₃^- - N in the regions. Therefore, the regions need specific governance and management.