Groundwater Level Variation Effects on Nitrogen Fate and Transport Under Simulating Rainfall

Through soil-column leaching experiment in laboratory, migration and transformation rule of nitrogen in different groundwater level dynamic under rainfall condition was studied. Using two groups of the same device, column I (water level rising) and column II (water level stability) at the same time simulate water level rise and stability to get the change of NO₃^--N, NO₂^--N and NH₄⁺-N concentration. The experiment ran for 500h, and started by the rainfall. Comparing the change rule of NO₃^--N, NO₂^--N and NH₄⁺-N concentration when the test to 0, 100, 200, 300, 400 and 500 h. The results showed that: (1)The low NO₂^--N concentration, 19±0.2°C of temperature and 7.3±0.25 of pH throughout the whole experiment, (2)Under the rainfall condition saturated-unsaturated Do and Eh of the two soil column were all showed a trend of decrease, and soil column I seriously. The unsaturated NO₃^--N and NH₄⁺-N concentration of soil column I also showed a trend of decrease, and the amplitude were 58.9 ~ 59.9% and 66.1 ~ 70.4% respectively. NO₃^--N and NH₄⁺-N concentration of column II also showed a trend of decrease, and the amplitude were 48.9~58.4% and 77.7~81.3% respectively. Unsaturated soil NO₃^--N of soil column I decrease obviously, and unsaturated soil NH₄⁺-N of column II obviously, (3)Saturated NO₃^--N concentration of soil column I decrease, but NH₄⁺-N concentration increase. Saturated NO₃^--N concentrations of soil column II increase, the NH₄⁺-N concentration decreased.