Nitrate Removal Across Ecogeomorphic Zones in Wax Lake Delta, Louisiana (USA)
Abstract
Delta wetlands retain nutrients and limit nitrate flux to the sea, but variations in flow and reaction kinetics across topography and through vegetation communities lead to heterogeneous nutrient removal rates. Understanding these relationships could help in predicting which delta morphotypes are more effective at nutrient retention, and in developing land reclamation projects to optimize this retention. To understand the spatial distribution of nitrate removal in a river-dominated delta, we deployed 29 mesocosms (open atmospheric benthic chambers) across ecogeomorphic zones with varying elevation, water depth, vegetation and sediment grain size on Mike Island in Wax Lake Delta (Louisiana, USA). Chamber measurements suggest that submerged levees of both primary and secondary channels represent the most reactive ecogeomorphic zones and may serve as hotspots of nitrate removal. Open water lagoons were associated with the lowest nitrate removal rates. A multiple linear regression model, relating specific environmental variables to potential nitrate removal rates, provides a way to upscale chamber measurements to the entire delta. Environmental parameters such as land surface elevation, water depth and nitrate concentration are important predictors of nitrate removal rate in Wax Lake Delta. A better understanding of how removal kinetics vary across ecogeomorphic zones can improve reactive transport models and help optimize wetland restoration projects to maximize nitrate removal.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B41D..01K
- Keywords:
-
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0442 Estuarine and nearshore processes;
- BIOGEOSCIENCES;
- 0497 Wetlands;
- BIOGEOSCIENCES;
- 4825 Geochemistry;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL