Water Resources Research Act Program

Details for Project ID 2019MO149B

Nonpoint source pollution mitigation in an urban watershed

Institute: Missouri
Year Established: 2019 Start Date: 2019-05-31 End Date: 2020-05-30
Total Federal Funds: $22,000 Total Non-Federal Funds: $44,079

Principal Investigators: Dr. Dev Niyogi

Abstract: Nonpoint sources of pollution can lead to increased nutrients, sediments, harmful microorganisms, and metals in urban watersheds. Excess nutrient and sediment delivery to streams and lakes in Missouri can promote eutrophication and the development of harmful algal blooms. In turn, these algal blooms can compromise municipal water supplies, pose a threat to the health of impacted aquatic ecosystems, and cause negative economic impacts on fisheries and recreation. Sources of phosphorus and nitrogen in urban stormwater can be linked to vegetation (leaves and grass), soils and eroded sediments, direct leaching from paved surfaces, leaking municipal wastewater pipes, animal waste, and fertilizers. We propose to explore several approaches to mitigating nutrient pollution in urban watersheds with application to two small, eutrophic urban ponds in Rolla, Missouri. One main approach will be floating treatment wetlands (FTW), a new technique where aquatic vegetation is suspended in the water column of streams and lakes to take up nutrients with plant growth. We will compare nutrient uptake of FTW systems to aquatic plants and algal mats, which already exist in the urban study ponds. For all approaches, we will use three main experimental settings to measure nutrient cycling of nitrogen and phosphorus: laboratory microcosms, field-scale mesocosms, and in-situ studies of uptake across the main flow paths into the pond. The main objectives of the proposed research are as follows: (1) to evaluate the viability of the different approaches with respect to the removal of nitrogen and phosphorus from urban ponds, (2) to evaluate the long-term fate of nitrogen and phosphorus taken up by plants and algae over the course of a growing season, specifically checking for release of nutrients with biomass death, and (3) to evaluate the optimal harvesting strategies to remove plant and algal biomass over the course of a growing season to maximize removal of nutrients from the pond while maintaining high uptake of nutrients. Results from the urban ponds will be compared with similar field studies of two unimpacted, reference ponds. The information gained in this research will be used to help guide decision makers and stakeholders on best management practices regarding urban stormwater treatment and mitigation of eutrophication. Broader impacts include advancement toward more sustainable management of water resources. Long term benefits of sustainable water management gained from this study can apply to other settings in Missouri and elsewhere, leading to a reduction in excess nutrient exports to lakes and marine environments. During the first year of this project, we have characterized the nutrient inputs to the urban ponds during storms in different seasons. We have also developed microcosms for measuring uptake of nutrients by specific taxa of macrophytes. Both of these advances will lead into more detailed studies in the 2nd year, where specific taxa and harvesting strategies will be explored in mesocosms and pond settings.