Abstract

Phosphorus (P) is an essential nutrient that can limit biological activity in some environments. Yet, many components of its cycle remain unclear, including P uptake and cycling in deep-sea sediments. These are critical, since a significant portion of Earth’s prokaryotes thrives in deep marine sediments, which are thought to mainly contain low bioavailable P in mineral phases. This suggests that microorganisms possess mechanisms to utilize recalcitrant P pools. The work performed focuses on identifying possible P sources to the deep biosphere, as well as microbial uptake mechanisms using stable oxygen isotope ratios in phosphate and ³¹P nuclear magnetic resonance spectroscopy on sediment samples collected during IODP 336 Expedition (North Pond).