Co-evolution of life and the environment on early Earth; study of the microfossil record associated with major climatic and geochemical oscillations in the Neoproterozoic.
Marine chemistry: distribution of trace elements in the ocean and their use as paleochemical tracers; response of the ocean to anthropogenic lead emissions; relation between dust, iron in the ocean, and marine biological activity.
Ocean circulation: dynamics of the ocean and climate, atmospheric and oceanic turbulence, air-sea interactions, the energetics of the ocean circulation, the impact of ocean physics on biology, and paleoclimate.
Ocean modeling: development of software, computing infrastructure and numerical algorithms for simulation of atmospheric, oceanic and geophysical flows.
Climate and the general circulation of the atmosphere and oceans; development of mathematical and numerical models of key physical and biogeochemical processes, oceans and climate, and paleoclimate.
Interplay among atmosphere, rock, water and microbes; the photochemical sulfur isotope effect, early microbial evolution, deep biosphere, and seafloor hydrothermal deposits.
Dynamical organization of the natural environment through investigation of the cooperative phenomena underlying common yet poorly understood observations. Work combines theory, field observations, and experiments to study problems including the carbon cycle and climate, the co-evolution of life and the environment, and the dynamics of fluids, rocks, and sand.
My research focuses on using atmospheric chemistry modeling to inform decision-making strategies on air pollution, climate change and hazardous substances such as mercury and persistent organic pollutants (POPs).
Biogeochemistry and geobiology: lipid chemistry of geologically significant microbes and microbial ecosystems; organic and isotopic indicators of climate change; evolution and mass extinction; biomarkers in sediments and petroleum; and biogeochemical fossils.
Understanding ocean circulation and its implications for climate and paleoclimate by combining global general circulation models and the recently available global data sets.