Compound-Specific δ13C of n-Alkanes: Clean-Up Methods Appraisal and Application to Recent Sediments of a Highly Contaminated Bay Milena Ceccopieri Arthur L. Scofield Lilian Almeida Angela L. R. Wagener 10.6084/m9.figshare.7243733.v1 https://scielo.figshare.com/articles/dataset/Compound-Specific_13C_of_n-Alkanes_Clean-Up_Methods_Appraisal_and_Application_to_Recent_Sediments_of_a_Highly_Contaminated_Bay/7243733 <div><p>Different clean-up methods to determine isotopic composition of n-alkanes were tested. Sources of organic matter in Guanabara Bay were re-examined through the δ13C of individual n-alkanes in surface sediment samples. The n-alkanes were efficiently isolated without significant losses of the compounds of interest. The δ13C of n-alkanes (n-C17 to n-C35) ranged between -34.0 and -26.4‰. More depleted δ13C values associated to higher carbon preference index (CPI > 4) suggest prevalence of biogenic n-alkanes from terrestrial origin in the inner stations influenced by inputs from mangrove areas. Small isotopic differences between odd and even-numbered chains and 13C-enrichment in long-chain homologues indicate a petrogenic hydrocarbons contribution. Higher concentrations of short-chain compounds associated to a more 13C-enriched total organic carbon (TOC) were found near the most intense sewage discharges. Results show that δ13C of n-alkanes can be applied to a highly degraded system as the Guanabara Bay and help improve the characterization of the organic matter.</p></div> 2018-10-24 02:43:48 GC-C-IRMS UCM urea adduction organic matter Guanabara Bay