HR: 12:05h
AN: B12B-08    [Abstracts]
TI: Natural abundance 14C analysis of biomarkers: A further tool for understanding microbial metabolism in the environment
AU: * Slater, G F
EM: gslater@mcmaster.ca
AF: McMaster University, 1280 Main St. West, Hamilton, ON L8S 4K1 Canada
AU: * Slater, G F
EM: gslater@mcmaster.ca
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Rd, Woods Hole, MA 02543 United States
AU: Eglinton, T I
EM: teglinton@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Rd, Woods Hole, MA 02543 United States
AU: Reddy, C M
EM: creddy@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Rd, Woods Hole, MA 02543 United States
AB: On April 27, 2004 the barge Bouchard 120 spilled ~400,000 liters of No. 6 fuel oil into Buzzards Bay, MA and contaminated ~200 km of rocky and sandy beaches. To investigate the short-term fate of the spilled oil on one of the rocky beaches (Nyes Neck), oil-covered rocks were collected and analyzed by comprehensive two-dimensional gas chromatography (GCxGC). Within several weeks, the major removal processes were evaporation and water-washing, but microbial degradation of n-alkanes became evident in mid June 2004 and continued through July and August. In order to confirm that the observed losses of n-alkanes were due to microbial activity, select rocks collected in mid July 2004 were analyzed for the stable carbon and radiocarbon content of phospholipid fatty acids (PLFA). These results indicate that the active community living on these oil-covered rocks was predominated by algae due to the presence of polyunsaturated C:20 PLFA that represented 48.4 mole percent of the PLFA at the site. The ubiquitous C16:0 and C18:0 PLFA made up 18.9 and 15.2 mole percent respectively, and PLFA commonly associated with bacteria, C16:1, C17:0, C18:unsaturated, and C20:0 made up a cumulative 14.4 mole percent. Compound specific 13C analysis yielded ambiguous results and gave no clear indication of petroleum metabolism by the microbial community. In contrast, 14C analysis of the individual PLFA clearly demonstrated that microbial uptake of the petroleum carbon was occurring. The 14C content of the algal PLFA (33.4 permil) closely matches that of Buzzards Bay dissolved inorganic carbon (51-62 permil), but the bacterial PLFA were strongly depleted in 14C (-230 permil). The ubiquitous C16 and C18 PLFA fell between these values (-8 and -39 permil respectively). These observed depletions could only be due to incorporation of the petroleum carbon, which has a 14C of -1000 permil. Thus compound specific radiocarbon analysis has proved to be an excellent tool for identification of microbial metabolism of petroleum carbon in the environment and provides a further tool to be added to that of 13C analysis. Additionally, the extent of 14C depletion of the bacterial PLFA gives an indication of the relative importance of petroleum carbon as a carbon source in this microbial community, the remainder of the carbon presumably coming from recycling of carbon from the bacterial and algal community and potential dissolved organic carbon in Buzzards Bay.
DE: 4857 Pollution
DE: 1055 Organic geochemistry
DE: 1094 Instruments and techniques
DE: 1615 Biogeochemical processes (4805)
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting