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Dissimilatory Nitrate Reduction to Ammonium (DNRA) Can Undermine Nitrogen Removal Effectiveness of Persistently Reducing Riparian Sediments
https://orcid.org/0000-0001-8032-6809
Denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) compete in reducing sediment conditions where DNF permanently removes nitrogen (N), while DNRA retains N with the conversion of nitrate (NO3 –) to ammonium (NH4 +). Thus, an increase in the level of DNRA can undermine permanent N removal. We investigated the relative magnitude and controls of these two processes at two milldam-affected riparian sites. DNRA (5.2–37.6 μg L–1 h–1) accounted for 10–79% of total NO3 – reduction and was highest in riparian sediments with higher iron (Fe) and sodium (Na+) in groundwater. DNF was the primary mechanism for NO3 – reduction when Fe and Na+ concentrations were low but when NO3 – was elevated. DNRA rates were higher for treatments with higher dissolved organic carbon (DOC):NO3 – and Fe:NO3 – ratios, indicating the stimulation of both heterotrophic and Fe2+ driven autotrophic DNRA. DNF and DNRA rates and their microbial functional genes decreased with increasing sediment depths. These findings imply that hydrologically stagnant and persistently reducing conditions associated with relict milldams and similar anthropogenic structures may enhance DNRA at the expense of DNF and undermine permanent N removal in riparian zones. Thus, the effects of such structures need to be accounted for in watershed N management strategies.
Limited research has been conducted on DNRA and denitrification in freshwater riparian zones affected by dams. According to our findings, stagnant water and persistently reducing conditions created by dams may promote DNRA at the expense of denitrification, undermining long-term N removal in riparian zones.
Dissimilatory Nitrate Reduction to Ammonium (DNRA) Can Undermine Nitrogen Removal Effectiveness of Persistently Reducing Riparian Sediments
https://orcid.org/0000-0001-8032-6809
Denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) compete in reducing sediment conditions where DNF permanently removes nitrogen (N), while DNRA retains N with the conversion of nitrate (NO3 –) to ammonium (NH4 +). Thus, an increase in the level of DNRA can undermine permanent N removal. We investigated the relative magnitude and controls of these two processes at two milldam-affected riparian sites. DNRA (5.2–37.6 μg L–1 h–1) accounted for 10–79% of total NO3 – reduction and was highest in riparian sediments with higher iron (Fe) and sodium (Na+) in groundwater. DNF was the primary mechanism for NO3 – reduction when Fe and Na+ concentrations were low but when NO3 – was elevated. DNRA rates were higher for treatments with higher dissolved organic carbon (DOC):NO3 – and Fe:NO3 – ratios, indicating the stimulation of both heterotrophic and Fe2+ driven autotrophic DNRA. DNF and DNRA rates and their microbial functional genes decreased with increasing sediment depths. These findings imply that hydrologically stagnant and persistently reducing conditions associated with relict milldams and similar anthropogenic structures may enhance DNRA at the expense of DNF and undermine permanent N removal in riparian zones. Thus, the effects of such structures need to be accounted for in watershed N management strategies.
Limited research has been conducted on DNRA and denitrification in freshwater riparian zones affected by dams. According to our findings, stagnant water and persistently reducing conditions created by dams may promote DNRA at the expense of denitrification, undermining long-term N removal in riparian zones.
Dissimilatory Nitrate Reduction to Ammonium (DNRA) Can Undermine Nitrogen Removal Effectiveness of Persistently Reducing Riparian Sediments
https://orcid.org/0000-0001-8032-6809
Denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) compete in reducing sediment conditions where DNF permanently removes nitrogen (N), while DNRA retains N with the conversion of nitrate (NO3 –) to ammonium (NH4 +). Thus, an increase in the level of DNRA can undermine permanent N removal. We investigated the relative magnitude and controls of these two processes at two milldam-affected riparian sites. DNRA (5.2–37.6 μg L–1 h–1) accounted for 10–79% of total NO3 – reduction and was highest in riparian sediments with higher iron (Fe) and sodium (Na+) in groundwater. DNF was the primary mechanism for NO3 – reduction when Fe and Na+ concentrations were low but when NO3 – was elevated. DNRA rates were higher for treatments with higher dissolved organic carbon (DOC):NO3 – and Fe:NO3 – ratios, indicating the stimulation of both heterotrophic and Fe2+ driven autotrophic DNRA. DNF and DNRA rates and their microbial functional genes decreased with increasing sediment depths. These findings imply that hydrologically stagnant and persistently reducing conditions associated with relict milldams and similar anthropogenic structures may enhance DNRA at the expense of DNF and undermine permanent N removal in riparian zones. Thus, the effects of such structures need to be accounted for in watershed N management strategies.
Limited research has been conducted on DNRA and denitrification in freshwater riparian zones affected by dams. According to our findings, stagnant water and persistently reducing conditions created by dams may promote DNRA at the expense of denitrification, undermining long-term N removal in riparian zones.
Dissimilatory Nitrate Reduction to Ammonium (DNRA) Can Undermine Nitrogen Removal Effectiveness of Persistently Reducing Riparian Sediments
Rahman, Md. Moklesur (author) / Peipoch, Marc (author) / Kan, Jinjun (author) / Sena, Matthew (author) / Joshi, Bisesh (author) / Dwivedi, Dipankar (author) / Gold, Arthur J. (author) / Groffman, Peter M. (author) / Galella, Joseph G. (author) / Inamdar, Shreeram (author)
ACS ES&T Water ; 4 ; 3873-3881
2024-09-13
Article (Journal)
Electronic Resource
English