Dr. Stewart is a biogeochemist with interest in the interactions between organisms and elemental cycling, particularly in the ocean. Currently she uses natural radionuclides to investigate the trophic transfer and bioaccumulation of metals by plankton, as well as to trace organic carbon cycling in the surface ocean. Her work sheds light on the mechanisms of contaminant accumulation in ecosystems as well as the ocean’s potential to sequester atmospheric carbon dioxide, a greenhouse gas. Further, her research into the behavior of present-day radioactive tracers may provide insight into the use of naturally-occurring paleotracers in the ocean. Primarily she has focused her research on the unique, short-lived, particle-reactive isotope polonium-210. At Queens College she has pursued regional environmental contaminant studies, done local research on the impacts of anthropogenic regional warming, and continues her work on large-scale oceanographic questions. She has been an active participant in the international GEOTRACES project.
Possible Future and Student Projects
- Metal accumulation and distribution in local coastal waterways
- The influence of dust on carbon assimilation in plankton
- Development of more specific environmental tracers for elemental cycling
- The importance of food web structure in determining bioaccumulation
- The effect of different particle types on radioisotope fractionation
- Species-specific nutrient uptake and loss in the plankton