[1] Univ Calif Irvine, Dept Earth Syst Sci, Irvine, CA 92697 USA
[2] Jackson State Univ, Dept Phys Atmospher Sci & Gen Sci, Jackson, MS 39217 USA
[3] Australian Nucl Sci & Technol Org, Environm Div, Menai, NSW 2234, Australia
[4] Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80301 USA
[5] Univ Florida, Dept Bot, Gainesville, FL 32611 USA
[6] CALTECH, Pasadena, CA 91125 USA
[7] Univ Alaska, Inst Arctic Biol, Fairbanks, AK 99775 USA
[8] US Geol Survey, Menlo Pk, CA 94025 USA
[9] Univ Colorado, Boulder, CO 80309 USA