The Study Of Nitrogen Distribution Characteristics In Groundwater And Soil And Pollution Sources Tracing In Groundwater Of The Typical Basin

Water pollution is restricting Chinese and global major issues for the sustainable development of social economy. The source of Non-point source pollution is varied, complicated composition and difficult to research and control. This study aimed at comparing the similarities and differences of non-point source pollution in different media of Chao River Basin and Hun River Basin Shen Fu period. We researched the water and soil pollution, influence factors and nitrogen pollution sources in different river basin by the traditional chemical analysis method of water (descriptive statistics method, Piper diagram, columnar index content distribution and kriging interpolation method, etc.) and multivariate statistical analysis method (cluster analysis and factor analysis). The main results were as follows:(1) For the Chao River Basin, ① there is a serious nitrogen pollution in the basin. The over standard rate of the nitrate in groundwater during rainy and dry seasons in Chao River Basin is 57.14% and 52.94% respectively. And the content of nitrogen in groundwater and soil during rainy season is significantly higher than dry season.② The type of groundwater quality is mainly Ca-HCO3 during the rainy season, while 50% of the groundwater quality type has changed for Ca-SO4. The water chemistry and multivariate statistical analysis reveals several hydrogeochemistry control factors of groundwater. In the northwestern, natural hydrogeochemical action (upstream runoff recharge, vertical infiltration, leached effects, etc) is the main controlling factor. The surface polltion source and the recharge of Chao river or Miyun reservoir play sn important roles in groundwater component in the eastern region.③ Through the spearman correlation analysis, the land use type is main influencing factor for the nitrogen pollution in groundwater and soil. The influence order is village> farmland> grassland> forest land> surface water. ④ Source tracing by isotope shows that the major source of nitrate in groundwater is manure or sewage during rainy season, and the contribution rate is nearly 100%. In this season, the denitrification is weak. The major source of nitrate in groundwater is fertilizer or rainfall, soil organic nitrogen, manure or sewage during dry season, and the contribution rate are 19.35%,38.71% and 41.94% respectively.(2) For the Hun River Basin Shen Fu period, ① there is a serious nitrogen pollution in the basin too. The over standard rate of the nitrate in groundwater during dry seasons in Hun River Basin Shen Fu period is 35.85%. And the content of nitrate (2.40 mg/L) and nitrite (0.16 mg/L) is significantly lower during rainy season than dry season (the content of nitrate and nitrite is 11.74 mg/L and 0.32 mg/L). The content of other nitrogen pollutants in groundwater and soil during rainy season is higher than dry season. ② The type of groundwater quality is mainly Ca-HCO3 during the rainy season, while 27% of the groundwater quality type has changed for Ca-SO4. The water chemistry and multivariate statistical analysis reveals several hydrogeochemistry control factors of groundwater. The surface polltion source and the recharge of Hun river plays an important roles in groundwater component in the central region. In the northweste and southeast region, natural hydrogeochemical action (upstream runoff recharge, vertical infiltration, leached effects, etc) is the main controlling factor. ③ Through the spearman correlation analysis, the land use type is main influencing factor for the nitrogen pollution in groundwater and soil. The influence order is village> farmland> grassland> forest land> surface water.④ Source tracing by isotope shows that the major source of nitrate in groundwater is manure or sewage during rainy season, and the contribution rate is nearly 80.56%. In this season, the denitrification is weak. The major source of nitrate in groundwater is fertilizer or rainfall, manure or sewage during dry season, and the contribution rate are 70.69% and 29.31% respectively.