The Raymond lab in collaboration with the Saiers lab at FES, and scientists at the USGS, Holy Cross, and UGA are beginning a recently funded NSF MacroSystems project. The project will look at carbon in the CT river watershed. The transfer of carbon, nutrients, and pollutants from terrestrial environments to streams and the biogeochemical transformations of these constituents within river networks are issues that motivate environmental scientists and water-resource managers. Dissolved organic matter (DOM) is a master variable in streams and rivers that affects contaminant speciation and mobility, light penetration, stream metabolism, pH, and water-treatment efficiency. The goals of this study are to (i) improve approaches for predicting DOM pulses from head-water catchments and (ii) advance understanding of factors that consume and alter DOM during its transit through the downstream drainage network.
We will continue to refine a new model suitable for quantifying DOM transfer from the landscape to streams draining head-water catchments. This model links rainfall-runoff processes that generate stream flow to biogeochemical processes that govern the quantity and composition of terrestrial DOC through changes in catchment-water storage. The model will be tested against measurements of DOM concentration and composition made in several headwater (1st-order) streams of the Connecticut River from Connecticut to Vermont. DOM fluxes and composition measurements (optical and FTICR-MS) will also be made in 2nd – 5th-order streams within the Connecticut River, thereby illuminating the manner in which DOM composition evolve along the drainage network. We will use these observations to test hypotheses for river-network DOM dynamics that are based alternatively on the classical River Continuum concept and our newly proposed Pulse-Shunt concept. We will also monitor and model the response of a large New England watershed to hydrologic acceleration.