Determination of oxygen, nitrogen, and sulfur-containing polycyclic aromatic hydrocarbons (PAHs) in urban stream sediments

摘要

Recent studies indicate that PAH transformation products such as ketone or quinone-substituted PAHs (OPAHs) are potent aryl hydrocarbon receptor (AhR) activators that elicit toxicological effects independent of those observed for PAHs. Here, we measured eight OPAHs, two sulfur-containing (SPAH), one oxygen-containing (DBF), and one nitrogen-containing (CARE) heterocyclic PAHs (i.e. Sigma ONS-PAHs = OPAH(8) + SPAH + DBF + CARB) in 35 stream sediments collected from a small (similar to 1303 km(2)) urban watershed located in south-central Pennsylvania, USA. Combined Sigma ONS-PAH concentrations ranged from 59 to 1897 mu g kg(-1) (mean = 568 mu g kg(-1); median = 425 mu g kg(-1)) and were 2.4 times higher in urban versus rural areas, suggesting that activities taking place on urban land serve as a source of Sigma ONS-PAHs to sediments. To evaluate urban land use metrics that might explain these data, Spearman rank correlation analyses was used to evaluate the degree of association between Sigma ONS-PAH concentrations and urban land-use/land-cover metrics along an urban-rural transect at two spatial scales (500-m and 1000-m upstream). Combined Sigma ONS-PAH concentrations showed highly significant (p < 0.0001) correlations with Sigma PAH(19), residential and commercial/industrial land use (RESCI), and combined state and local road miles (MILES), suggesting that Sigma ONS-PAHs originate from similar sources as PAHs. To evaluate OPAH sources, a subset of Sigma ONS-PAHs for which reference assemblages exist, an average OPAH fractional assemblage for urban sediments was derived using agglomerative hierarchal cluster (AHC) analysis, and compared to published OPAH source profiles. Urban sediments from the Condoguinet Creek (n = 21) showed highly significant correlations with urban particulate matter (X-2 = 0.05, r = 0.91, p = 0.0047), suggesting that urban particulate matter is an important OPAH source to sediments in this watershed. Results suggest the inclusion of Sigma ONS-PAH measurements adds value to traditional PAH analyses, and may help elucidate and refine pollutant source identification in urban watersheds. (C) 2015 Elsevier Ltd. All rights reserved.