Mechanisms of trace element deposition from the free atmosphere to surfaces in a remote High Sierra Canyon

Abstract

Field experiments to determine size distributions and deposition rates of airborne K, Rb, Cs, Ca, Sr, Ba, and Pb were conducted in Thompson Canyon, California (elevation 3000 m) during 1976 and 1977 in order to study deposition mechanisms at this remote site. The data suggest that sedimentation accounts for most of the deposition of the first six elements on smooth, flat surfaces in winds of 2 m s −1, but that turbulent inertial deposition becomes more important at greater windspeeds. Pb is found in smaller particle sizes and is less influenced by sedimentation. The data and associated calculations also suggest that inertial impaction plays a dominant role in transporting these elements to pine needle surfaces in the canyon.