Nitrate transport behavior behind subsurface dams under varying hydrological conditions
Yunhai Fang1, Tianyuan Zheng1, Huan Wang2
1College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment Science and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China.
The Science of the Total Environment
|May 19, 2022
Summary
Subsurface dams can increase nitrate contamination in coastal aquifers. Tides significantly worsen this pollution, with their combined effect being greater than the sum of individual impacts.
Area of Science:
- Hydrogeology
- Environmental Science
- Water Resource Management
Background:
- Subsurface dams are used to control seawater intrusion in coastal aquifers.
- Nitrate accumulation upstream of these dams raises concerns for freshwater sources.
- Previous research often simplified sea boundary conditions, neglecting tidal influences.
Purpose of the Study:
- To investigate the combined effects of tides and subsurface dams on nitrate pollution.
- To analyze nitrate contamination dynamics in upstream groundwater under various scenarios.
- To quantify the impact of tidal fluctuations on nitrate accumulation.
Main Methods:
- Laboratory experiments were conducted to simulate groundwater conditions.
- Numerical simulations were employed to model nitrate transport.
- Various scenarios including static, tidal, dam presence, and combined effects were analyzed.
Main Results:
- Both tides and subsurface dams increase upstream nitrate contamination.
- Higher tidal amplitudes lead to greater nitrate contamination.
- The joint action of tides and dams resulted in a synergistic increase in pollution (51.10%) exceeding individual effects (9.47% for dams, 37.22% for tides).
Conclusions:
- Tidal fluctuations are a critical factor in nitrate contamination assessments for coastal aquifers with subsurface dams.
- Effective management strategies must account for tidal impacts to ensure freshwater source viability.
- Ignoring tidal effects can lead to underestimation of nitrate pollution risks.
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