PAHs in dated sediments of Ashtabula River, Ohio, USA

Polycyclic aromatic hydrocarbons (PAHs) in dated sediments from Ashtabula R iver, Ohio, were determined, and a chemical mass balance (CMB) model was us ed to apportion sources. Three cores (AR-1,AR-2, AR-3) were dated by correl ating uranium-supported Pb-210 peaks with 1964, 1972, 1977, and 1979 maxima in the discharge record for Ashtabula River. These cores had sedimentation rates between 7.1 and 4.4 cm/year, while a fourth (AR-4) exhibited a much higher rate of 27.8 +/- 18 cm/year. The highest PAH concentration was 11500 ng/g found in layer 6 of AR-1 (1986), and the lowest was 621 ng/g found in layer 8 of AR-2 (1982), The source contributions to the total PAH concentr ations estimated by the CMB model are 0.1-2.2%, 16.8-22.8%, and 78.1-83.8% for wood burning (WB), coke oven (CO), and highway dust (HWY), respectively . Petroleum generated PAHs have maximal contribution during 1977-79, and wo od burning PAHs show minimal emissions during 1975-77 in accordance with U. S. consumption records and other studies. Among six PAH markers, only phena nthrene may be subjected to aerobic biodegradation or photolysis with an ap parent half-life of 0.005-0.025 year. No anaerobic degradation was observed based on the CMB model. The model works well for the nonmarker compounds,f luoranthene, and benzo[b]fluoranthene/benzo[k]fluoranthene.