The goal of this project is to develop, evaluate, and utilize an airborne instrument to measure two of the most important chemical forms of mercury (Hg): gaseous elemental mercury (GEM) and reactive gaseous mercury (RGM). The instrument will quantify RGM by two methods, one with one-hour resolution and a second with 2.5-minute resolution. Data from the two techniques will be compared and the uncertainty of the RGM measurements will be assessed. This will enable the first high time resolution observations of both GEM and RGM by aircraft and allow the following questions on the atmospheric mercury cycle to be addressed: 1) Do the two different airborne RGM measurements agree within their respective uncertainties? 2) Do GEM observations by aircraft agree with observations at the Mt. Bachelor Observatory in Oregon? 3) Can air masses with elevated RGM, seen previously at Mt. Bachelor and predicted by models to be present over the southwest U.S., be identified? If so, what are the chemical and meteorological controls on RGM in the western U.S.? 4) What is the distribution of GEM and RGM in the troposphere? 5) Can airborne measurements be used to quantify the flux of GEM and RGM from industrial sources? This project should lead to a better understanding of the chemical processing of atmospheric mercury and its sources and sinks in the U.S.
Bioaccumulation of mercury is a problem with global and national significance because of its health impacts. One postdoctoral fellow and one undergraduate student from the University of Washington will participate in the project.
