In the oceans, physical forcing (solar input) drives the distribution and chemical composition of water masses which strongly influence biological productivity. Reciprocally, oceanic biota affect the physical and chemical properties of seawater. EOS research in biogeochemistry seeks to understand the interactions between ocean physics, chemistry and biology, by integrating our strengths in each of these sub-disciplines.
While EOS research in geophysical fluid dynamics contributes a better understanding of heat and energy transport in oceanic water masses, the research in biogeochemistry examines how the physical movement of seawater (both horizontally and vertically) is coupled spatially and temporally to biological production. As an example, one area of particular interest is the extent to which tidal mixing in estuaries affects nutrient and light availability for phytoplankton (single celled photosynthetic organisms), as well as the distribution of zooplankton (small animals which feed on the phytoplankton). Other key areas of interest include the effects of water circulation rates on subsurface oxygen concentrations and the role of various physical processes in partitioning biologically produced gases across the air-sea interface.
From a chemical perspective, our research is focused on developing new analytical methods to examine the spatial and temporal distribution of elements and molecules in seawater. We are interested in measuring the total concentration and isotopic composition of a wide range of analytes, including various transition metals, trace gases and dissolved organic compounds. We are also investigating the production of a number of important biomolecules-including harmful toxins and beneficial therapeutics-produced by a variety of marine organisms. In addition to their intrinsic biochemical importance, these biogenic compounds also provide clues about the past and present environmental conditions experienced by marine organisms.
As we continue to develop new oceanographic measurement approaches, we are also refining our interpretations of the physical and chemical observations we make. We seek to understand qualitatively and quantitatively how biological processes (e.g. photosynthesis, respiration, denitrification etc.) can affect the distributions of key elements in seawater, and the fluxes of matter between the ocean, atmosphere and lithosphere. Much of this work is based upon numerical models that assimilate physical, chemical and biological data, and reproduce observed patterns based upon prescribed mechanistic relationships. As we improve our ability to model chemical distributions in the oceans, we can begin to use these chemical signatures to yield information on key biological processes.
Much of this research focuses on the direct measurement of biological activity in marine waters. Collectively, we examine the factors that regulate the productivity and biological diversity of viruses, bacteria, phytoplankton and zooplankton, and the controls on energy flow between these trophic levels. Our work has examined how natural and anthropogenic climate change may affect the activities of individual organisms and the structure of entire oceanic communities.
(* - more than 25; ** - more than 50; *** more than 100 citations.)
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