Wetlandscape Management: Maximizing US Nitrate Removal Through Wetland Protection and Restoration
Abstract
Growing populations and agricultural intensification have led to raised riverine nitrogen (N) loads, widespread coastal hypoxia, and increases in the incidence of algal blooms. Although recent work has suggested that individual wetlands have the potential to improve water quality, little is known about the current magnitude of wetland N removal at the landscape scale. Here we use National Wetland Inventory data and 5km2 grid-scale estimates of N inputs and outputs to demonstrate that current N removal by US wetlands (about 860 ± 160 kilotonnes of nitrogen per year) is limited by a spatial disconnect between high-density wetland areas and N hotspots. We then used modelling to compare the potential water quality benefits and costs associated with different large-scale wetland management strategies. Our model simulations suggest that future restoration efforts of 10% wetland area (5.1 million hectares) using a spatially targeted approach across the US can double current wetland N removal. This increased removal would provide an estimated 54% decrease in N loading in nitrate-affected watersheds such as the Mississippi River Basin. The costs of this increase in area would be approximately 3.3 billion US dollars annually across the USAnearly twice the cost of wetland restoration on non-agricultural, undeveloped landbut would provide approximately 40 times more N removal. Our results suggest that wetland protection and restoration policies need to reduce the spatial disconnect between N sources and wetlands to have significant improvements to downstream water quality.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H11F..06C