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(P191) Concentrations, aerial distribution, and sources of polycyclic aromatic hydrocarbons in pine needles from Houston.
Hwang, Hyun-Min*,1,2, Wade, Terry1, Sericano, Jose1, 1 Geochemical and Environmental Reserach Group, Texas A&M University, College Station, TX, USA2 Department of Chemistry, George Mason University, Fairfax, VA, USA
ABSTRACT- Pine needle samples were collected from 18 sites in Houston, TX in February 2000 to investigate the concentrations, aerial distribution, and sources of polycyclic aromatic hydrocarbons (PAHs). Pine needle samples (10 g, wet wt.) were extracted with dichloromethane, cleaned by Si/Al column chromatography and further purified using gel-permeation HPLC. Identification and quantification were performed using a GC equipped with a mass selective detector (MSD). Since waxy cuticular lipid layer of pine needles adsorb organic contaminants by partitioning from the air, PAHs on pine needles can be used as surrogates of the concentrations of atmospheric PAHs. Total PAH concentrations ranged from 353 to 2226 (ng/g, dry wt.) and are similar to other urban areas. The highest and lowest concentrations were found in samples from the center of Houston (City hall) and a suburban site in the southern part of Houston, respectively. PAH concentrations were highest at sites near highly populated areas, where fuel consumption (e.g., traffic activity) is high. Three ring PAHs were dominant in all samples and accounted for 42 to 63% of the total PAHs. Phenanthrene was the predominant compound. The PAH congener distribution patterns were fairly constant in all samples, indicating the same PAH sources. PAHs from both combustion and petroleum sources are present. One likely source of combustion PAHs is vehicle emission. Other sources include volatilization of petroleum (e.g., spills, processing, natural seeps). Pine needles are useful passive samplers of atmospheric PAHs.
Key words: PAHs, Pine needles, Houston, Aerial distribution
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