HR: 0800h
AN: A51A-0035    [Abstracts]
TI: Influence of African Dust and Volcanic Ash on the Chemical Composition of Cloud/Rain Water Collected in a Tropical Montane Cloud Forest in Puerto Rico
AU: * Reyes-Rodríguez, G J
EM: gabillo2000@gmail.com
AF: Institute for Tropical Ecosystem Studies, University of Puerto Rico, PO Box 21910, San Juan, PR 00931, Puerto Rico
AU: * Reyes-Rodríguez, G J
EM: gabillo2000@gmail.com
AF: Department of Chemistry, University of Puerto Rico, PO Box 23346, San Juan, PR 00931, Puerto Rico
AU: Gioda, A
EM: adriana@adam.hpcf.upr.edu
AF: Institute for Tropical Ecosystem Studies, University of Puerto Rico, PO Box 21910, San Juan, PR 00931, Puerto Rico
AU: Gioda, A
EM: adriana@adam.hpcf.upr.edu
AF: Department of Chemistry, University of Puerto Rico, PO Box 23346, San Juan, PR 00931, Puerto Rico
AU: Mayol-Bracero, O L
EM: omayol@adam.uprr.pr
AF: Institute for Tropical Ecosystem Studies, University of Puerto Rico, PO Box 21910, San Juan, PR 00931, Puerto Rico
AU: Mayol-Bracero, O L
EM: omayol@adam.uprr.pr
AF: Department of Chemistry, University of Puerto Rico, PO Box 23346, San Juan, PR 00931, Puerto Rico
AU: Collett, J
EM: collett@atmos.colostate.edu
AF: Department of Atmospheric Science, Colorado State University, 1371 Campus Delivery, Fort Collins, CO 80523, United States
AB: Some organic compounds present in aerosols are surface active and their presence in cloud condensation nuclei can affect the surface tension of cloud droplets. The nature of these surface active compounds in clouds and rainwater is not well understood and there is very little information about their content in remote tropical environments. Therefore, our study focuses on the chemical characterization of the organic component of cloud and rainwater samples collected in a tropical montane cloud forest on the island of Puerto Rico. Samples were collected during periods of varying air mass origin, including periods of influence by African dust and by volcanic ash. Cloud samples were collected using a compact version of the single-stage Caltech Active Strand Cloudwater Collector. Rain samples were collected using a passive collector. The organic fraction of collected samples was characterized using a total organic carbon and total nitrogen analyzer (TOC/TN) and nuclear magnetic resonance (1H-NMR) spectroscopy. Elemental and organic carbon (EC, OC) were determined for suspended particles contained in collected cloud and rainwater samples. These particles were also analyzed using scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) to determine their elemental compositions. Preliminary results indicate that average concentrations of cloud water TOC ranged from 0.9 to 1.2 mg/L. Lower concentrations were observed in rainwater, 0.3 to 0.7 mg/L. TN concentrations were higher than TOC in cloud water samples when air masses came from the African continent. The suspended aerosol particles had a content of 2.0 µg of OC per mL of cloud water, but EC was not detected. Suspended particle analysis by SEM-EDS showed Si, Al, and Fe, which have crustal origin, as the predominant species. The 1H-NMR spectra showed alcohols in large quantities, suggesting the presence of biogenic material or polyols when air masses arrived from the African continent. A more complete set of results including volcanic ash events from the Soufriere Hills in Montserrat will also be presented.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting