Research Statement

Nitrogen Export to the Long Island Sound: Determining Fluxes and Processes within the Connecticut River Watershed.

Nitrogen is the limiting nutrient in many estuaries and increasing the availability of this nutrient often leads to the eutrophication of these systems. Estuarine eutrophication is associated with higher rates of algal net primary production, seasonal hypoxia, deceased habitat, toxic algal blooms, fish kills, and changes to the plant and animal communities. In order to reduce nitrogen loading to coastal waters it is necessary to determine the relative significance of both point and non-point sources. Researchers have repeatedly found that non-point sources often contribute the majority of nitrogen to coastal watersheds. While the dominance of non-point sources is not true of all systems, deciphering their role in the total nitrogen export to any estuary is an important step towards effectively managing nitrogen loads. Large-scale empirical models have repeatedly shown that there is a significant reduction in N loads by a variety of in-stream processes. However, the role of individual processes, such as assimilation and denitrification, within riverine environments is still largely uncertain.

My research focuses on determining the processes and fluxes important to nitrogen export from a large temperate watershed. In order to examine nitrogen fluxes and processes I sample at multiple watershed scales, ranging from ~5 km2 to ~1500 km2. Sampling occurs throughout the Connecticut River watershed, encompassing both spatial and seasonal variations in source contributions and biogeochemical processing. An integral component of this work is with the measurement of both d15N and d18O of NO3-, the dominant form of nitrogen, on a variety of spatiotemporal scales. Many studies have used this dual isotope technique to partition sources of nitrogen to a watershed, but not on this spectrum of spatial scales.