HR: 0800h
AN: A41A-0019    [Abstracts]
TI: Characterization of Airborne Particulate Matter During Lake Breeze Events in Chicago
AU: * Schmeling, M
EM: mschmel@luc.edu
AF: Loyola University Chicago, Department of Chemistry 6525 N. Sheridan Rd., Chicago, IL 60626 United States
AU: Fosco, T
EM: tfosco@luc.edu
AF: Loyola University Chicago, Department of Chemistry 6525 N. Sheridan Rd., Chicago, IL 60626 United States
AB: Particulate air pollution is a constantly growing problem in urban areas. The particulate matter present in pollution events contains often toxic or health impacting species and is responsible for low visibility, might be triggering respiratory diseases like asthma, and can play an important role in formation or duration of smog events. It is not unlikely that local meteorological events such as lake breezes might exacerbate a pollution situation by transporting processed air masses containing secondary pollutants back to shore. To characterize pollution patterns associated with lake breeze events in Chicago, aerosol filter samples were collected for determination of elemental and ionic aerosol composition before and during a lake breeze. Sampling took place at Loyola University Chicago Air Station (LUCAS) during the summer months of 2002 to 2004. The station is located in close proximity to Lake Michigan and therefore ideally suited to observe this event. In addition to atmospheric aerosol sampling, reactive trace gases were monitored and an automated weather station recorded major meteorological parameter. The particulate samples were analyzed by total reflection X-ray fluorescence after digestion of the filter matrix to quantify the elemental concentration in the aerosol and by ion chromatography for determination of ionic species. The results showed that concentrations of some elements, most notably sulfur, increased during a lake breeze significantly as opposed to reference days without a lake breeze. The sulfate concentrations determined by ion chromatography confirmed these findings. High sulfate concentrations are indicative for a processed air mass transported by the lake breeze to the measurement station. As the same air mass was residing above Lake Michigan before onset of the lake breeze, we think that photochemical reactions, initiated by intense sunlight in summer, converted primary species into secondary ones, which were brought back by the lake breeze. This was supported by an increase in nitrate concentrations and elevated ozone mixing ratios shortly after the lake breeze did set in. The results obtained suggest that a lake breeze pattern like occurring in Chicago could have major implications for coastal environments with respect to local climate and human health.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0345 Pollution--urban and regional (0305)
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting