Polycyclic aromatic hydrocarbons (PAH) are common pollutants of aquatic
systems in urban environments. Due to their lipophilicity, persistence, toxicity and
carcinogenicity, they are chemicals of considerable concern. The Portland Harbor
includes a large industrial section with numerous current and historic sources for PAH
contamination. Runoff from a large metropolitan area and a populated river basin
provide additional sources for PAH contamination.
We used semi-permeable membrane devices (SPMDs) to passively sample the
dissolved fraction of PAH in a 17-mile stretch of the Willamette River, encompassing the Portland Harbor and a 6 mile federal superfund site. We sampled during the summer and fall of 2001 in order to look at any change in bioavailable PAH concentration that
may be attributable to episodic storm events or effects from heavy runoff. In response to
high PAH concentrations found in the industrial section of the river during 2001, we
performed an intensive sampling in the lower Portland Harbor in September, 2002. In
this study, 16 EPA-designated priority pollutant PAH were analyzed (Figure 1).
Our data indicate that there is a background level of dissolved, bioavailable PAC that remains fairly steady throughout the upstream portion of the study area, ranging from
10-25 ppt. This may be attributed to the combination of multiple non-point sources.
Dramatic increases in total PAH concentration, 10-20-fold, indicate that there is at least
one point source of PAH in the lower Portland Harbor. Our subsequent sampling in 2002 strongly indicate that a substantial portion of this PAH concentration is originating from a
historic creosote manufacturing facility, McCormick & Baxter. Forensic comparison
between the PAH distribution found in the Portland Harbor and that found in fresh
creosote further support this. A similar distribution in the upper harbor indicates that
PAH contaminants in this region also originate from a variety of pyrolysis sources.
Significant seasonal differences were found between the dry months of August
and September and the rainy months of October and November. PAH concentrations
were on average higher in the summer months; however, total PAH load in the river
reached a maximum in November. Additionally, localized distribution of contaminant
plumes was effected by changes in river flow and water velocity. These results have
implications for both the organism and ecosystem level.
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