Welcome!

The Saltzman/Aydin Research Group at UC Irvine studies the global cycling and impacts of atmospheric trace gases.  We are focused on the following questions:

  1. What controls the production, emissions, and atmospheric chemistry of trace gases emitted by natural or anthropogenic activity?
  2. What is the history of atmospheric composition and what does it tell us about global biogeochemical cycling and climate?

The trace gases we study include are mostly short-lived (a few years or less), are present in the atmosphere at low levels (parts-per-billion or parts-per-trillion), and have some strong connection to the climate system. We develop methods for trace gas detection and study their distributions in the modern and ancient atmospheres.  Our work has taken us aboard research ships, to remote island research stations, and to the polar ice sheets in Greenland and Antarctica.  

Air bubbles and aerosols trapped in deep polar ice cores from Greenland and Antarctica are an amazing amazing archive of ancient air.  We analyze the chemistry of these ice cores to reconstruct changes in atmospheric composition on long time scales.  From these records we can examine how man’s activities have affected atmospheric chemistry, and study the relationship between trace gases, climate change, and global biogeochemical cycles.

Each trace gas has its own complex biogeochemical cycle.  Here are some examples of specific trace gases we have studied:

  • dimethysulfide – a sulfur gas produced by oceanic phytoplankton, which is a precursor for atmospheric sulfate aerosols, and cloud condensation nucleii in the marine atmosphere.  Our recent work has focused on the process of air/sea exchange that releases dimethylsulfide into the 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.
  • acetylene – a “pyrogenic” hydrocarbon that is produced by combustion of fossil fuels, wildfire, and biofuels.  Variations of acetylene in the preindustrial contain unique information about biomass burning emissions and how they vary on long time scales.
  • methyl bromide and methyl chloride – these are major natural sources of stratospheric bromine and chlorine which contribute to stratospheric ozone depletion. Methyl bromide and methyl chloride are produced in both the both terrestrial ecosystems and in the oceans.