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SALINITY INDUCED NITROGEN AND PHOSPHORUS RELEASE IN NORTH CAROLINA COASTAL FORESTED WETLANDS

Coastal wetlands act as an important biofilter between inland and marine habitats by sequestering nutrients. However, coastal wetlands are particularly vulnerable to increased salinization from sea level rise and saltwater intrusion. Increased salinization has been shown to lead to the release of stored nutrients due to salinity induced desorption of nitrogen and phosphorus. We evaluated ammonium (NH₄⁺) and phosphate (PO₄^3-) desorption in response to a range of salinities from freshwater to sea water (0, 3, 10, and 35 ppt Cl^-) on soils from two natural, and one restored forested wetland. Soil ammonium concentrations in the restored wetland (5.6 µg cm^-3 soil) are double that in the natural wetlands (1.2 and 2.3 µg cm^-3 soil). Despite the large difference in NH₄⁺ concentration, all three wetlands responded similarly to the addition of salt, with a rapid increase in NH₄⁺ desorption up to 10 ppt Cl^- concentration, then leveling off. We did not observe any clear patterns of PO₄^3- desorption in response to salinity. This work is contributing to our understanding of how sea level rise and saltwater intrusion affect nutrient cycling in coastal wetlands.

Matthew Stillwagon (Primary Presenter/Author), North Carolina State University, mgstillw@ncsu.edu;


Emily Bernhardt ( Co-Presenter/Co-Author), Duke University, ebernhar@duke.edu;


Justin Wright ( Co-Presenter/Co-Author), Duke University, justin.wright@duke.edu;


Marcelo Ardon ( Co-Presenter/Co-Author), North Carolina State University, mlardons@ncsu.edu;