INFLUENCE OF SOIL CHEMISTRY ON CARBON AND NUTRIENT LIBERATION IN SLEEPERS RIVER WATERSHED

Dissolved organic carbon, nitrogen and phosphorous (DOC, TDN and TDP) are of critical importance to natural biogeochemical cycles. In recent decades, increased concentrations of DOC have been observed in northern surface waters recovering from acid deposition (Seifert-Monson et al., 2014). Such increases in DOC can significantly alter the productivity of surface waters, although the consequences vary based on previous trophic conditions (Seekell et al., 2015). The primary mechanism controlling the increased flux of DOC into surface waters has yet to be concretely established. Furthermore, potential effects on nutrients (N and P) have not been assessed either. In a combined lab and field study we investigate the effects of changes in ionic strength and pH on DOC, TDN, and TDP mobilization from soils. Using riparian and hillslope soils collected from the Sleepers River USGS research station, we measured dissolved species concentrations in a series of aqueous soil extractions using solutions of varying pH, ionic strength and composition. Lower ionic strength solutions released greater concentrations of DOC and TDN from the soils suggesting disaggregation as an important carbon and nutrient source.

References:

Seekell, D. A., Lapierre, J. F., Ask, J., Bergstrom, A. K., Deininger, A., Rodriguez, P., & Karlsson, J. (2015). The influence of dissolved organic carbon on primary production in northern lakes. Limnology and Oceanography, 60(4), 1276-1285. doi:10.1002/lno.10096

Seifert-Monson, L. R., Hill, B. H., Kolka, R. K., Jicha, T. M., Lehto, L. L., & Elonen, C. M. (2014). Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland. Soil Biology and Biochemistry, 79, 91-99. doi:10.1016/j.soilbio.2014.09.007