Excess nutrients in the environment have led to deleterious water quality effects, including widespread freshwater and marine eutrophication and harmful algal blooms. Decades of research suggest the potential for individual wetlands to remove nutrients (e.g., nitrogen and phosphorus), via processes such as denitrification, plant uptake, and phosphate sorption to prevent their transport to downstream waters. However, many scientific questions remain regarding the role of wetlands in mediating water quality, and specifically nutrient pollution, at watershed scales. In this presentation we explore how wetlands attenuate nutrient pollution across watersheds of the Upper Mississippi River Basin (UMRB), an approximately 490,000 km2 system. We use two primary approaches: (1) modifying existing process-based models to integrate landscape wetlands into large-scale hydrological models and (2) applying statistical approaches on available spatial and “big” data to gain insights into how various landscape network nodes (e.g., surface depressions, wetlands) and edges (flowpaths) interact with sources to influence total nitrogen (TN) and total phosphorus (TP) concentrations. The former approach affords hydrological improvements in large scale process-based modeling to support quantification of nutrient dynamics in wetlands. The latter provides key insights on the degree to which landscape nodes, edges, and sources of nutrients influence TN and TP within the UMRB.
Results/Conclusions
Our results point to two key findings: (1) wetlands hold considerable potential to mediate watersheds-scale nutrient yields and (2) research scientists and managers need to begin integrating wetlands into watershed scale hydrological and nutrient fate and transport modeling to improve simulated outcomes. This research is the first, to our knowledge, to link these “natural infrastructure” features to water quality across large river basins, providing supportive research for future nutrient management.