Seasonal Aerosol Distributions at Summit, Greenland: EC, OC, 14C and Individual Particle Analysis
G. Klouda1, J. Conny1, D. Earnhardt2, A. McNichol3 and J. Dibb4
1Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899; 301-975-3931, E-mail: george.klouda@nist.gov
2Old Dominion University, Norfolk, VA 23529
3National Ocean Sciences Accelerator Mass Spectrometry Facility, Woods Hole Oceanographic Institution, Woods Hole, MA 02543
4Complex Systems Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH 03824
Aerosol is known to affect the Earth’s atmosphere and surface albedo thus having an influence on climate. In the case of carbonaceous aerosol, Organic Carbon (OC) tends to scatter sunlight while Elemental (soot) Carbon (EC) aerosol absorbs light. Considering the importance of these aerosols on snow and ice albedo (Hansen and Nazarenko, 2004), PM2.5, PM2.5-10 and snow-melt filters were collected at Summit, Greenland from August 2000 to August 2002 to measure particulate EC, OC, and 14C of total carbon; the latter to assess natural and anthropogenic source contributions. Additional source information was gleaned from scanning electron microscopy images (SEM) of single particles from selected filters. All samples were collected within a clean air sector upwind from the campsite only when winds were within–sector (180 °S ± 150 °) and –wind speed (> 1.3 m s-1). Preliminary analyses of PM2.5 results suggest spring-summer maxima of EC and OC (Figure 1). Summer concentrations are consistent with summer 2006 measurements reported by Hagler et al. (2007). The average percent modern carbon from a subset of filters over the two-year period was 44% (SD=18%; n=19). Figure 2 shows focused ion beam SEM images of soot (left) and likely mineral dust (center, right).
Figure 1. Greenland PM2.5, EC, and OC concentrations.
Figure 2. FIB-SEM images of PM2.5 collected during 3 – 10 July 2001.