T5 PM Emerging Pollutants
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in 321-323
(GOE-1117-827535) Factors influencing air concentrations of polybrominated diphenyl ethers in rural Maryland and Delaware.
Goel, A.1, McConnell, L.2, Torrents, A.1, Scudlark, J.3, Simonich, S.4, 1 University of Maryland, College Park, MD, USA2 United States Department of Agriculture, Beltsville, MD, USA3 University of Delaware, Lewes, DE, USA4 Oregon State University, Corvallis, OR, USA
ABSTRACT- Polybrominated Diphenyl Ethers (PBDEs) are an emerging class of pollutants which have been detected in almost all environmental compartments, including human milk. Even so, data on their atmospheric presence is lacking. Aerial concentrations of penta BDEs, almost exclusively used in North America and the most toxic and bioaccumulable of the various congeners, were monitored at three sites on the predominantly rural Delmarva Peninsula. Two of the sites are close to the Atlantic coast in Delaware (Dover and Lewes) and the third is near the mouth of the Choptank River in Maryland (Horn Point). 24-h weekly air samples (n=240, 2001-2003) were collected using high volume air samplers. Overall, BDE congeners 47, 99 and 100 were detected most frequently at 58%, 60%, and 39%, respectively. However, the three sites differed in terms of PBDE occurrence and concentrations. The average concentrations at Horn Point and Dover (BDE 47: 13-19 pg/m3; BDE-99: 5.4-6.6 pg/m3) are comparable to that observed in rural Canada (BDE-47: 4.6 pg/m3; BDE-99: 4.3 pg/m3), suggesting that these sites reflect background levels. Lewes was different in that it had average concentrations that were up to 5-10 times higher than the other two sites. The spring-buffering effect of emerging foliage was weak at Lewes; the concentrations were high in the warmer months (
PBDEmax= 910 pg/3) and showed significant correlation with temperature. The calculated heats of phase transition (53-21 kJ/mol) are much lower than the heats of vaporization of these compounds suggesting that vaporization from surfaces is not the controlling factor. Back trajectory analysis for the three sites suggests that the concentrations increase as the air mass travels over the Peninsula. Spray irrigation of treated municipal wastewater, a common practice for the counties on the Delmarva Peninsula, is suspected to be a source of PBDEs in the air at Lewes. Several spray irrigation facilities are located to the south and west of Lewes, the general wind direction during the spring and summer time when most of our samples were collected. The aerial concentrations at Lewes are also increasing at an exponential rate; the atmospheric doubling times for the different congeners range from 1.1-2.4 yrs.
Key words: PBDEs, Chesapeake Bay, atmospheric concentrations, atmospheric transport