HR: 1340h
AN: A53C-1358    [Abstracts]
TI: A new Isotope Tracer to Identify Long Range Transport and Transformation of Aerosol
AU: * Shaheen, R
EM: robina@ucsd.edu
AF: Univ. of Karachi, Int. Center for Chemical and Biological Sciences, Karachi, 75270, Pakistan
AU: Abramian, A
EM: kusachka@yahoo.com
AF: Univ. of California San Diego, 9500 Gilman Dr. 0356, La Jolla, CA 92093, United States
AU: Dominguez, G
EM: gdominguez@ucsd.edu
AF: Univ. of California San Diego, 9500 Gilman Dr. 0356, La Jolla, CA 92093, United States
AU: Bluen, B
EM: bbluen@ucsd.edu
AF: Univ. of California San Diego, 9500 Gilman Dr. 0356, La Jolla, CA 92093, United States
AU: Jackson, T
EM: tjackson@ucsd.edu
AF: Univ. of California San Diego, 9500 Gilman Dr. 0356, La Jolla, CA 92093, United States
AU: Thiemens, M H
EM: mthiemens@ucsd.edu
AF: Univ. of California San Diego, 9500 Gilman Dr. 0356, La Jolla, CA 92093, United States
AB: It is of interest to understand the intercontinental transport of dust particles because they can accumulate anthropogenic nitrate, sulphate and carbonaceous compounds (black carbon and aromatic hydrocarbon) on their surfaces by adsorption during transportation. Carbonate is a prominent component of the soils in north western China where much of the Asian dust is produced. Carbonate can affect atmospheric chemical processes and aerosol characteristics because the acid neutralizing capacity of this species facilitates the heterogeneous conversion of sulphate and nitrate The primary goal of this work is to develop an isotope methodology for carbonates that can be used as a chemical marker for the origin of polluted air plumes. The results will be compared with other established tracers such as nitrate and sulphate that possess anomalous oxygen isotopic composition in polluted environments from reaction with ozone. Aerosol samples were collected on filter papers using Anderson Cascade Impactors at two different locations in La Jolla, California: one at the Scripps Pier and the other one at coastal Mount Soledad (800 ft). The particulate samples were allowed to react with excess H3PO4 at 28 oC for 14h and the gaseous compounds released were collected at liquid nitrogen. CO2 gas was separated from other reaction products by gas chromatography. In order to measure the oxygen isotope composition, CO2 gas was fluorinated to release oxygen gas to be analysed on the isotope ratio mass spectrometer. We discuss the carbon and oxygen isotope composition of the CO2 released from the fine (< 1 um) and coarse (> 1um) particles collected at two different sites (Mt. Soledad and Scripps Pier) and its utility as a tracer to identify the long range transport of aerosol from local pollution events. The secondary organic oxidation products and concomitant isotope may provide a new indicator of chemical transformation. The transport situation of the air parcels will be analyzed through back trajectory analysis from sampling sites based on National Oceanic and Atmospheric Administration (NOAA) data (http://www.noaa.gov/).
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting