|Title||Wintertime concentrations and sinks of atmospheric particulate carbon at a rural location in northern Michigan|
|Publication Type||Journal Article|
|Year of Publication||1988|
|Authors||Cadle SH, Dasch JMuhlbaier|
Particulate elemental carbon, organic carbon, and SO4-2 wintertime atmospheric concentrations were determined at a rural site in northern Michigan during two winters. Examination of the concentrations, based on both surface-wind direction and backward-trajectory analysis, indicated that concentrations were significantly influenced by the long-range transport of pollutants. Measurements of the wet- and dry- deposition rates of elemental carbon showed that it is removed primarily by wet deposition at this site. The dry deposition velocity of elemental carbon to a snow surface averaged < 0.2 cm/s during most of the study, but was considerably higher for one period during which it appeared to be influenced by large particles from local sources. A comparison of the scavenging ratios of SO4-2 and elemental carbon shows that snow removes SO4-2 at least twice as efficiently as elemental carbon. This difference implies that the atmospheric residence time of elemental carbon in the winter will be considerably longer that that of SO4-2, if precipitation occurs. In the absence of precipitation, the estimated residence time of elemental carbon is at least 6 days. These results suggest that elemental carbon can be transported long distances and, thus, may degrade visibility and have other effects over wide regions.