Nitrate Removal and Nitrate Removal Velocity in Coastal Louisiana Freshwater Wetlands

Abstract

Nitrate removal and nitrate removal velocity rate were determined for Mississippi River deltaic plain forested-tupelo dominated wetland, and a floating emergent freshwater marsh. Nitrate removal rate from floodwater was 19.45 and 48.90 mg N m⁻² d⁻¹ for two forested-tupelo wetland sites and 48.41 and 46.98 mg N m⁻² d⁻¹ at two floating emergent freshwater marsh sites. The removal velocity constants (k) of NO₃-N ranged from 0.44 to 1.44 per day for the four site studies. Removal velocity of nitrate from the water column was faster in the floating emergent marsh cores than from the forested wetland course, which contained more sediment. Results demonstrated that removal velocity is an important parameter when estimating nitrate removal from floodwater. Results also demonstrated the two freshwater wetland habitats had a high capacity for processing any nitrate entering the wetlands from adjacent agriculture area. Removal was attributed to denitrification and diffusion.

Keywords:

• Acetylene inhibition
• Denitrification
• Intact core
• Nitrate removal
• Removal velocity

Acknowledgments

This work was supported by the Louisiana Department of Environmental Quality and by the National Research Foundation of Korea Grant funded by the Korean Government (Ministry of Education, Science and Technology). [NRF-2010-359-F0003].

Notes

†k: NO₃-N removal velocity constant.

*^, **denotes significance at 5.0 and 1.0% level, respectively.