One of the most important ways that microorganisms interface with the environment is through their processing of carbon, from greenhouse gases to the synthesis and degradation of long-lasting organic compounds. In an effort to quantify how dynamic organic carbon is in marine sediments, the underlying basaltic basement and shales, we use modeling and analytical techniques as well as fieldwork to make the point that organic compounds are not intrinsically labile or recalcitrant, but exist on a continuum of reactivities determined by the biogeochemical setting.
Ongoing projects include a multifaceted approach to examining how magmatic sills have influenced the microbiology and carbon cycling in Guaymas Basin, Gulf of California. Thermodynamic calculations, metagenomic data, isotopic measurements, microbial incubations and a collaborative network are being used to pursue this work. In another multi-disciplinary project, shales units in Southern California are being probed to quantify the degradation rate of petrogenic organic carbon as a function of age, diagenetic history and microbial communities. This work involves in situ CO2 evolution measurements, laboratory incubations, complex organics characterization, and modeling work.