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As the world’s climate changes, rural coastlines are becoming more vulnerable to sea level rise. Consequently, these ecosystems are undergoing major disruptions in nutrient cycling. Tidal salt marshes, riparian forests, and farmland converge on coastlines, forming ecotones, or unique transitional ecosystems. With centuries of farming and fertilizer additions, nitrogen (N) and phosphorus (P) in excess of plant demand can accumulate in soils (known as legacy nutrients). Sea level rise and associated saltwater intrusion following storm events can remobilize legacy nutrients years or even decades after application, supplying a persistent but unpredictable source of nutrients to downstream waterways. The proposed study will investigate the potential impact saltwater intrusion on P and N loading on the Lower Eastern Shore of Maryland using a combination of field measurements, lab experiments, and data synthesis. This work will build on a year of preliminary data, which indicates that saltwater intrusion on farm fields enhances the release of phosphate, nitrate, and ammonium and that these nutrients are accumulating in salt marshes downslope. By quantifying these inputs and delineating the key the biogeochemical processes that enhance nutrient release into waterways, this study will provide crucial information for land managers and conservation groups attempting to improve water quality in Maryland's coastal agricultural areas.
Tully, KL; Weissman, D; Wyner, WJ; Miller, J; Jordan, T. 2019. Soils in transition: saltwater intrusion alters soil chemistry in agricultural fields BIOGEOCHEMISTRY142(3):339 -356. doi:10.1007/s10533-019-00538-9. UM-SG-RS-2019-08.