Spatial and seasonal atmospheric PAH deposition patterns and sources in Rhode Island

Polycyclic aromatic hydrocarbons (PAH) enter the environment through various combustion processes and can travel long distances via atmospheric transport. Here, atmospheric PAM deposition was measured in six locations throughout Rhode Island using passive atmospheric bulk-deposition samplers for three years. The measurements were evaluated using two source-specific PAM isomer signatures, a multivariate receptor model, and an innovative contamination index that is weighted based on PAM contamination, number of detected compounds, and toxicity. Urban areas had significantly higher deposition rates (up to 2261 mu g m(-2) yr(-1) Sigma PAH) compared to pen-urban, coastal, and rural areas (as low as 73.6 mu g m(-2) yr(-1) Sigma PAH). In fall and winter, PAM deposition was up to 10 times higher compared to summer/spring. On an annual basis a total of 3.64 t yr(-1) Sigma PAH (2256.9 mu g yr(-1) m(-2) Sigma PAH) are estimated to be deposited atmospherically onto Rhode Island. Both, the analysis using isomer ratios and the statistical analysis using positive matrix factorization agreed on source identification. Overall gasoline, petrodiesel, and oil combustion sources were identified in all samples year-round while wood combustion associated PAH deposition was only detected during the cold season. (C) 2015 Elsevier Ltd. All rights reserved.