Citation:

Forshay, K., J. Weitzman, J. Wilhelm, J. Hartranft, D. Merritts, M. Rahnis, R. Walter, AND P. Mayer. Unearthing a stream-wetland floodplain system: increased denitrification and nitrate retention at a legacy sediment removal restoration site, Big Spring Run, PA, USA. BIOGEOCHEMISTRY. Springer, New York, NY, (161):171-191, (2022). https://doi.org/10.1007/s10533-022-00975-z

Impact/Purpose:

Based on previous studies, sediment and nutrient loads that flow to the Chesapeake Bay and other estuaries on the East Coast may be derived from “legacy sediments” that fill valley bottoms throughout the Mid-Atlantic region. These sediments filled floodplains beginning with land conversion to agriculture during the American Colonial era and the ubiquitous use of mill dams for hydropower.  Although the mills are gone, the sediments remain, continually eroding and moving tons of sediment downstream carrying nitrogen and phosphorous.  In collaboration with Pennsylvania Department of Environmental Protection, we examined the effects of removing legacy sediments as a stream restoration approach to manage nitrogen at experimental restoration at Big Spring Run in Lancaster, PA.    We describe the changes in sediment and water concentrations of nitrogen and organic carbon, denitrification, nitrification, and carbon mineralization, before and after legacy sediment removal.  Our results show that sediment and water nitrate concentrations decreased after restoration due to increased carbon availability and subsequent microbial activity and nitrate removal.  We conclude that legacy sediment removal and floodplain reconnection can lead to the accumulation of organic C and improved nitrate retention over time.  Therefore, legacy sediment removal may be a cost-effective BMP for nutrient management. 

Description:

Journal article on research conducted on a restored stream-floodplain in PA. The research focused on legacy sediment removal and increases of denitrification and nitrate retention.

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