Abstract
Because of the nitrogen pollution problem in groundwater, the migration conversion mechanism of nitrogen in groundwater level fluctuations was analyzed. Technology and methods through indoor experiments and theoretical analysis were used to study coarse sand, medium sand, and fine sand groundwater level fluctuation in the aeration zone and saturated zone under the situation of nitrogen distribution characteristics, revealing groundwater level fluctuation with the nitrogen migration mechanism. The experimental results showed that the variation range of the nitrate-nitrogen (NO3−−N) concentration with the water level is medium sand > fine sand > coarse sand. The ammonium nitrogen (NH4+−N) concentration showed a downward trend after water level fluctuations, and there were more apparent fluctuations in coarse sand and medium sand. The nitrite nitrogen (NO2−−N) in coarse sand and medium sand first increased the water level and then gradually reached a balance. The sampling points below the water level in fine sand showed a downward trend with fluctuation of the water level, and then gradually reached equilibrium. The results provide a scientific basis for the remediation and treatment of soil and groundwater pollution.
Highlights
Due to industrial wastewater, domestic sewage, livestock feces, excessive use of chemical fertilizer [1], atmospheric settlement, and other factors, groundwater nitrogen pollution is severe; it has become a global environmental issue [2,3,4]
The dissolved oxygen content in coarse sand fluctuates most violently with the water level, and the reaction of medium sand is more vital than that of fine sand. This is because the particle size and porosity of coarse sand and medium sand are large, and the oxygen content in the aeration zone is more than that in fine sand
Groundwater level fluctuation can significantly affect the law of nitrogen migration and transformation in soil groundwater
Summary
Domestic sewage, livestock feces, excessive use of chemical fertilizer [1], atmospheric settlement, and other factors, groundwater nitrogen pollution is severe; it has become a global environmental issue [2,3,4]. The migration and transformation of nitrogen in the aeration zone and saturated zone has become a hot issue in environmental science, soil science, and groundwater science at home and abroad [6]. Affected by natural conditions and human activities, the groundwater level has significant dynamic variation characteristics. The changes in meteorological and hydrological conditions and human activities, such as groundwater exploitation, can cause the groundwater level, and there is a groundwater level wave band [7]. The aeration zone–saturated zone interface and capillary strips continue to change so that environmental factors, such as water power conditions, physical chemistry, and biological effects, vary with water levels, which in turn affect the migration of pollutants
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