This research effort will (1) quantify temporal variability in contributions of major sources of CO over the past several thousand years and (2) begin to investigate the corresponding trends in OH. The work is motivated by the need to better understand the background chemistry of the CH4-OH-CO system in today's atmosphere relative to the range in variability over the past. OH largely determines both the chemical oxidation mechanisms and the lifetimes of most reactive atmospheric species. Similarly, CO is one of the most important reactive trace gases in the atmosphere because of its combined reactivity and abundance. Because of the close link between CO and CH4, these studies will also help to resolve mechanisms that drove CH4 concentration changes in the past. CO concentration, 13CO, and C18O will be measured in air trapped in archived core samples of firn and ice. Delt17O in CO will be measured as a proxy of large-scale OH abundance and temporal variability. The application of delt17O to constrain atmospheric OH has been demonstrated but a new analytical approach with the capability to characterize low-volume air bubbles in ice cores is required to extend the record to the past. The Principal Investigator (PI) will construct a new analytical system to measure delt17O in CO in low-volume air bubbled based on the system currently used to measure 13C and 18O in CO from ice cores and an offline system designed to measure of delt17O in CO from larger whole air samples.
Quantifying OH variability is critical to understanding the overall fast photochemistry of the troposphere (NOx, CO, CH4, VOCs, SOx, secondary aerosols, etc.) and the lifetimes of H-containing greenhouse gases. One postdoctoral scientist and one graduate student will participate in and be trained through this project. In addition, two undergraduate geology majors at Stony Brook who plan to become high school teachers will be mentored by a local high school teacher. These undergraduate students will also mentor high school students in appropriate research topics through the PI's group. This pilot program will be evaluated by all students and teachers/advisors involved and, if successful, a broader program will be implemented.
