Hilary Close

Associate Professor

(305) 421-4306 x54306
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Assistant Professor, Department of Ocean Sciences - Rosenstiel School of Marine, Atmospheric, and Earth Science

I am a marine organic geochemist, broadly interested in picking apart the processes of production, physical movement or mixing, and degradation of organic matter in complex natural environments, with a goal toward understanding how ecological change translates into larger-scale effects on the marine carbon cycle. One of my main focuses is the biological carbon pump in present-day open-ocean water columns, from surface to lower mesopelagic depths. Specifically, I seek to clarify the roles of microbes in the production and degradation of marine organic matter, within the context of water column particle dynamics. Other research areas include investigating sources and bioavailability of organic matter in marginal marine sediments, identifying pathways for incorporation of microbial biomass into the higher food web, investigating the degradative impact of zooplankton on sinking particles, and fundamental questions regarding stable isotope effects during microbial carbon uptake, biosynthesis, and enzymatic degradation.

The primary tools I employ in my lab are natural-abundance isotope analyses of carbon and nitrogen: compound-specific stable isotope analysis of lipids and amino acids, bulk stable isotope analysis, and natural-abundance radiocarbon analysis of organic matter classes, as well as lipid “biomarker” profiling. Oceanographic field studies and modeling play important roles in my work. 

Field and analytical collaborations greatly enhance and extend the context in which we interpret geochemical data. Exciting areas for collaboration may involve marine microbiological studies, including proteomics and genomics, in situ and/or autonomous optical observations of particles and organic matter, other chemical and physical studies of water column environments, global biogeochemical modeling, remote sensing observations of productivity and element cycling, and geochemical applications to ancient environments.





B.A. Geology, Oberlin College
Ph.D. Earth and Planetary Sciences, Harvard University