A Coupled Hydrological and Biogeochemical Process Model for Fate and Transport of Nitrate in Agricultural Areas of Texas
Abstract
In agricultural areas the use of fertilizers to maintain high crop productivity contributes to high concentrations of nitrate in groundwater. The objective of the study is to accurately estimate historical and future nitrate concentration in domestic wells in agricultural areas in Texas. To date most transport models have focused on groundwater processes, neglecting critical biogeochemical processes that occur as contaminated water percolates through the soil profile. Transport, transformation, and distribution of nitrogen from the point of application through the soil profile to groundwater depend upon complex physical, biological, and chemical processes. We developed a mathematical model that accounts for key biogeochemical processes that occur as contaminated water is transported from the land surface to the groundwater. Key features of the model include: root growth, root uptake of nutrients, mineral precipitation-dissolution and biogeochemical cycles of carbon, nitrogen, iron and sulfur (C-N-Fe-S). The model also includes biological mediated secondary reactions. Depending on aquifer soils, crop type, irrigation technology and climate characteristics, secondary denitrification by ferrous iron may play an important role by inducing nitrate reduction at the interface between nitrate-rich percolating waters and highly-reduced waters. The improved model can be applied for: 1) estimate contaminant levels in a hindcast mode for conducting epidemiologic studies 2) evaluate physical, chemical or biological transformation rates of different contaminants for conducting mitigation studies; and 3) evaluate the effect of land-use change on contaminant concentrations in soil and groundwater aquifers for developing remediation strategies.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.H53B1033M
- Keywords:
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- 1831 HYDROLOGY / Groundwater quality;
- 1847 HYDROLOGY / Modeling;
- 1865 HYDROLOGY / Soils;
- 1875 HYDROLOGY / Vadose zone