Abstract
An investigation into the use of stable carbon isotopes (513C) as tracers of biodegradation of petroleum in estuarine sediments was performed. This technique uses the 813C of respired C02 as an indicator of the organic matter being degraded. The precision of this procedure in biometer flasks was determined to be ︢0.8 %. over an eight day period. This precision is sufficient to distinguish between petroleum hydrocarbons, which have a typical ratio from-30 to-26 %. depending on the petroleum, and for example, estuarine grasses that range from-1 6 to-1 0 %. or phytoplankton which have a ratio around-21.7%.. The carbon isotope discrimination between C02 and substrate during peak C02 production was less than 2.2 %. for all but one substrate tested. Experiments in which the C:N ratio varied, indicated that substrate availability, not nitrogen availability, affected the discrimination between C02 and substrate. Parallel 14C-CO2 experiments and gas chromatography analysis of residuals was performed for experiments with more than one possible substrate. Results from these analyses confirmed results from the 513C of the respired C02. Findings from the laboratory work indicated that stable carbon isotopes of respired C02 are useful in determining the substrate that is being utilized.
Hesse, Deborah Louise (1994). Stable carbon isotopes as an indicator of petroleum biodegradation in estuarine sediments. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -H5873.