MRI: Acquisition of a Nuclear Magnetic Resonance Spectrometer for Marine Biogeochemical Research

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

Ocean productivity, the health of our planet, and many of the resources foundational to our modern society, are in large part by-products by how very tiny, single celled microbes manufacture and degrade organic compounds in the ocean. Each day ocean microbes synthesize enormous quantities of proteins, sugars, and fats. In doing so, they manufacture a large share of the oxygen we breathe, they remove harmful carbon dioxide from the atmosphere, and they serve as food for many commercially important species of marine fish and crustaceans. Microbes "clean" seawater of pollutants, and serve as the base of marine ecosystems. However, marine microbes live a very competitive environment. The nutrients that microbes need to grow and thrive are extremely scarce, and nutrient cycling is extraordinarily efficient. Even small disturbances in microbial nutrient cycles can have major consequences; oxygen in seawater can disappear, and ecosystems can collapse. To understand how microbial cycles operate, we need to identify and track organic compounds and nutrients that are key to sustaining microbial life. Here we request funds to refurbish and modernize a nuclear magnetic resonance (NMR) spectrometer for use in a broad suite of marine biogeochemical studies designed to understand microbial nutrient cycles. The instrument will allow a number of scientists, students and staff at the Woods Hole Oceanographic Institution (WHOI) to identify key organic nutrient compounds that microbes use to extract nutrients from seawater, fend off predation, and shield themselves from harmful UV radiation. The instrument will also be critical to training the next generation of marine scientists through the WHOI postdoctoral and summer student fellowship programs, and the WHOI/MIT Joint Graduate Program in ocean sciences. Iron and phosphorus are two nutrients that limit and shape marine microbial communities across large tracts of the ocean. The chemical forms of marine iron and phosphorus are largely unknown, and over the next few years, we propose use the NMR spectroscopy to identify iron, copper, cobalt, and phosphorus containing organic compounds. Initial results have allowed us to show that the degradation of organic phosphonates is a source of atmospheric methane and ethylene, and that siderophores, compounds synthesized by marine microbes to extract iron from the environment, are actively produced in regions of the ocean where iron is scarce. We will continue this work through the US GEOTRACES program, which will measure trace metal and nutrient abundances across the Pacific Ocean from Alaska to Tahiti. Many organic compounds and organic nutrients are supplied by dust and river discharge into ocean margins. Determining the chemical identity of terrestrial organic matter entering the ocean, and its availability to marine microbial communities is key to understanding microbial nutrient cycles. A second focus of our research over the next few years will be in using enhanced NMR techniques to better characterize the nature and transformations of terrestrial organic matter as it enters the ocean. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.