Date

2019 12:00 AM

Major

Chemistry

Department

Chemistry

College

Liberal Arts and Sciences

Project Advisor

Steven Hall

Description

Anaerobic microbial communities in soils and sediments are responsible for metabolic processes such as iron (Fe) and nitrate (NO3-) reduction in wetlands, which may be linked to the cycling dynamics of several pollutants. However, the dynamics of Fe reduction in wetlands designed to intercept agricultural drainage water for NO3- reduction are still unknown. This study explored whether NO3- reduction and Fe reduction are segregated over time, due to NO3- reduction being more favored thermodynamically, using daily water samples collected from the inlets and outlets of two wetland research sites in Palo Alto County, Iowa. Samples collected from March to November of 2017 were analyzed for reduced (FeII) and oxidized (FeIII) concentrations by using colorimetric quantification with ferrozine. Nitrate concentrations were analyzed using spectrophotometry. Resulting data showed a clear trend of increased Fe concentrations after a decrease in NO3- concentrations at both the inlets and outlets of these wetlands. This is consistent with thermodynamic predictions that microbes use iron reduction for energy only after nitrate levels have been depleted. Our results suggest that elevated Fe fluxes, and therefore also pollutants linked to Fe cycling, can be predicted by evaluating the dynamics of NO3- fluxes through wetlands.

File Format

application/pdf

Share

COinS
 
Jan 1st, 12:00 AM

Analysis of Correlation between Iron and Nitrate Reducation in Wetlands Designed to Intercept Agricultural Tile Drainage

Anaerobic microbial communities in soils and sediments are responsible for metabolic processes such as iron (Fe) and nitrate (NO3-) reduction in wetlands, which may be linked to the cycling dynamics of several pollutants. However, the dynamics of Fe reduction in wetlands designed to intercept agricultural drainage water for NO3- reduction are still unknown. This study explored whether NO3- reduction and Fe reduction are segregated over time, due to NO3- reduction being more favored thermodynamically, using daily water samples collected from the inlets and outlets of two wetland research sites in Palo Alto County, Iowa. Samples collected from March to November of 2017 were analyzed for reduced (FeII) and oxidized (FeIII) concentrations by using colorimetric quantification with ferrozine. Nitrate concentrations were analyzed using spectrophotometry. Resulting data showed a clear trend of increased Fe concentrations after a decrease in NO3- concentrations at both the inlets and outlets of these wetlands. This is consistent with thermodynamic predictions that microbes use iron reduction for energy only after nitrate levels have been depleted. Our results suggest that elevated Fe fluxes, and therefore also pollutants linked to Fe cycling, can be predicted by evaluating the dynamics of NO3- fluxes through wetlands.