Detection of petroleum contamination in river sediments from Quebec City region using GC-IRMS

Isotopic analysis by compound specific gas chromatography-isotope ratio mas s spectrometry (GC-IRMS) is used to detect and characterize petroleum pollu tion in surficial sediments along the St Lawrence River, near Quebec City. Unusually mature n-alkane distributions have been found in some recent inte rtidal sediments in the region. GC-IRMS results suggest that the n-alkanes are not derived from indigenous organic sources because they carry delta(13 )C values between -30.0 and -27.0 parts per thousand, as well as very small isotopic differences between odd and even numbered n-alkanes, which are bo th typically associated with petroleum products. Comparison of these sedime nts with bunker fuel, an oil used in the shipping industry, has shown a clo se isotopic correlation in some sites, which is further supported by biomar kers. Overall, the contamination has been dispersed along the river but is generally localized around the industrial region where hydrocarbon transfer from shore storage to ships takes place. This study illustrates how GC-IRM S can be used effectively in the detection and characterization of petroleu m pollutants in sediments. (C) 1999 Elsevier Science Ltd. All rights reserv ed.