Sunrise in Woods Hole (Photo: Ben Van Mooy)
I use organic biomarkers and stable nitrogen and carbon isotopes to examine biogeochemical nutrient cycling and viral control of phytoplankton blooms in modern and ancient oceans and lakes. I am also developing organic proxies for identifying periods of increased aridity in the past, with the aim of increasing our understanding of regional variability and global climate change. I focus on pigments and lipids, abundant, biologically important compounds with sedimentary diagenetic products that contribute to biogeochemical interpretations. I have developed chromatographic methods for isolating and purifying pigments for compound-specific C and N stable isotope analysis. The isotopic analysis of these compounds required minimizing the sample size requirements of elemental analysis-isotope ratio mass spectrometry (EA-IRMS). These modifications resulted in nano-EA-IRMS, a system I developed as a graduate student in collaboration with Pratigya Polissar, a former postdoctoral researcher at Penn State. These chemical tools are broadly applicable to modern and ancient biogeochemical studies that aim to answer questions about biogeochemical cycling and microbial ecology.