Waiser, M. J.. Napier University, firstname.lastname@example.org
Robarts, R. J.. National Water Research Institute, email@example.com
DOM FROM SELECTED PRAIRIE AQUATIC ECOSYSTEMS: A COMPARISON OF COMPOSITION AND REACTIVITY.
Aquatic systems across the Canadian prairies contain high concentrations of dissolved organic matter (DOM) which may vary in composition and reactivity. Compositional differences in DOM from a prairie wetland and a saline lake were examined by isolating DOM using XAD-8 resins and then characterizing the eluted hydrophobic organic acids (HPOA) using 13C NMR and mass electrospray analysis, 13C signatures, 14C aging, and C:N ratios. As well, DOM from the freshwater inflow to the lake was compared to lake DOM using the same methods. HPOA from the wetland and saline lake are low in molecular weight (350-450 Daltons) and terrestrial in origin. DOM from the wetland, however, is much younger, has lower C:N ratios, and is more aromatic and colored than its saline lake counterpart. DOM from the inflow is significantly different from lake DOM as well. Experiments using natural microbial assemblages indicate that DOM reactivity (biological and chemical) varies across these systems. For example, the amount of biologically available DOM is greater in the wetland (19%) and inflow (12%) than in the lake (0%). Photolysis experiments indicate that DOM in the wetland and the lake can be broken down by UV light and subsequently utilized by bacteria.
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