The oceans produce a diverse array of trace gases that affect the chemistry of the atmosphere and the climate system. Our goal is to understand what controls the production, emissions, and atmospheric chemistry of oceanic trace gases. We develop trace gas detectors, collect field data from islands and ships and use computer models to simulate natural processes.
We are also interested in the history of trace gas/climate interactions. Air bubbles and aerosols trapped in deep polar ice cores from Greenland and Antarctica provide a sample of the ancient atmosphere. Our ice core studies involve field sampling and laboratory analysis of polar ice cores and air trapped in polar snow.
The trace gases we study include:
- dimethysulfide - a sulfur gas produced by oceanic phytoplankton, which is a precursor for atmospheric sulfate aerosols, and cloud condensation nucleii in the marine atmosphere.
- carbonyl sulfide - the most abundant sulfur gas in the atmosphere, a precursor for stratospheric sulfate, and a promising tracer for photosynthetic activity.
- alkyl nitrates - these gases are produced photochemically in the surface oceans by "smog-type" reactions. In marine air they are precursors of reactive nitrogen, and influence tropospheric ozone levels over remote oceanic regions.
- alkanes, acetone, and isoprene - hydrocarbons that influence the oxidation capacity of the troposphere and are useful tracers for biogeochemical or anthropogenic emissions.
- methyl halides - gases such as methyl bromide, methyl chloride, etc. which are major sources of stratospheric bromine and chlorine. These gases are both produced and destroyed in the oceans.
- reactive halogens (Cl2, Br2, I2, BrCl, HOCl) - these short-lived gases are produced by reactions involving marine aerosols. They are precursors of reactive chlorine and bromine atoms which may influence the reactivity of marine air and the atmospheric lifetimes of other trace gases, such as methane.