Carly Buchwald, Dalhousie: Oceanic Nitrogen Cycle

Описание: COMPASS 2025-04-04: Carolyn Buchwald, Dalhousie University
"Stable Isotopes: The Key to Deciphering the Oceanic Nitrogen Cycle"

Natural abundance stable isotopes of N and O in nitrite and nitrate are powerful tools for interpreting nitrogen biogeochemistry in the environment. The Buchwald Lab focuses on measuring the isotope systematics of relevant microbial nitrogen transformation processes and then using these values to interpret natural abundance isotopes in a wide range of environments, including wastewater, lakes, estuaries, rivers, and the ocean. We use stable isotopes of nitrogen in two main ways: (1) using 1D models to predict rates from profiles of natural abundance isotopes, and (2) using stable isotopes to fingerprint sources and sinks of nitrogen in the environment. In this talk I will present a case study from the Labrador Sea using natural abundance nitrate isotopes to predict rates of new production over the spring bloom. I will also present our ongoing and future work in Bedford Basin, a coastal fjord located in Halifax Harbor. Bedford Basin is highly impacted by anthropogenic activities, including Ocean Alkalinity Enhancement and wastewater effluent from multiple large treatment plants. We will use the stable isotopes of nitrogen species to determine the effect of these processes on the microbial nitrogen cycling.