| Popis: |
For years, the Illinois Institute of Technology (IIT) at Chicago has served as the only urban sampling site for the Integrated Atmospheric Deposition Network. Atmospheric concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides, and polycyclic aromatic hydrocarbons (PAH) in the vapor phase have been measured at this site every 12 days since 1993. These data have been used as representative urban regional concentrations, but these measurements may not be characteristic of the entire urban region. Thus, a second site at the University of Illinois at Chicago (UIC), which is closer to the downtown area than the IIT site, was operated from February through October 2002 to evaluate the possible urban source-influenced concentrations of these compounds. The average PCB concentrations at UIC are higher than that at IIT by a factor of ∼2; the PCB concentrations range from 670–4,600 pg/m3 at UIC and 310–3,000 pg/m3 at IIT. The pesticide and PAH concentrations at these two sites are in general agreement except for higher aldrin concentrations in some samples at IIT. |
