Baltimore Ecosystem Study Institute of Ecosystem Studies

2015 BES Annual Meeting Presentation and Poster Abstracts

Salinization alters fluxes of bioreactive elements from stream ecosystems across land use
Duan, Shuiwang
Co-Authors: Sujay Kaushal

Abstract: There has been increased salinization of fresh water over decades. Salinization can mobilize bioreactive elements chemically via ion exchange and/or biologically via influencing of microbial activity. We investigated potential impacts of increased salinization on fluxes of bioreactive elements from stream ecosystems and evaluated the implications of percent urban land use on salinization effects. Two- day incubations of sediments and soils with stream and deionized water across 3 salt levels were conducted at 8 routine monitoring stations across a land-use gradient at the Baltimore Ecosystem Study LTER site. Results indicated: (1) salinization typically increased sediment releases of labile dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), total dissolved Kjeldahl nitrogen (TKN), and sediment transformations of nitrate; (2) salinization generally decreased DOC aromaticity and fluxes of soluble reactive phosphorus (SRP) from both sediments and soils; (3) the effects of increased salinization on sediment releases of DOC and TKN and DOC quality increased with percentage watershed urbanization. Biogeochemical responses to salinization varied between sediments and riparian soils in releases of DOC, DIC, and nitrate transformations. The differential responses of riparian soils and sediments to increased salinization were likely due to differences in organic matter source and composition. Our results suggest that short-term increases in salinization can cause releases of significant amounts of labile organic carbon and nitrogen from stream substrates and organic transformations of nitrogen and phosphorus. Given that salinization of fresh water will increase in the future due to human activities, impacts on carbon and nutrient mobilization and water quality should be expected.