TITLE:
13C/12C Isotope Fractionation during Aerobic and Anaerobic Biodegradation of Naphthalene
AUTHORS:
Luis E. Lesser-Carrillo
KEYWORDS:
Naphthalene; Isotope; Fractionation; Enrichment; Aerobic; Anaerobic; Biodegradation
JOURNAL NAME:
International Journal of Geosciences,
Vol.5 No.2,
February
26,
2014
ABSTRACT:
Microcosm experiments were
conducted to determine the fractionation of stable carbon isotopes during
biodegradation of naphthalene. The microcosms were performed under aerobic
conditions, anaerobic (amended with sulfate, amended with nitrate and with no
amendments) and sterile controls. The liquid phase was analyzed to determine
naphthalene concentration and stable carbon isotope signature. Aerobic
microcosm showed that naphthalene degraded aerobically within 60 hours. The δ13C increased from -25.5‰ to -25.1‰ (enrichment of 0.4‰ ± 0.08‰) in a single sample in which 95% of the
naphthalene was biodegraded. Anaerobic microcosms show that after 288 days, the
microcosms with no amendments, amended with nitrate and amended with sulfate
had consumed respectively 30%, 50% and 60% of naphthalene on average, compared
to control microcosms. Under the denitrifying conditions, the δ13C of
naphthalene increased from -25.2‰ to -23.9‰ (enrichment of 1.3‰ ± 0.3‰)
after a 95% of naphthalene biodegradation. For the unamended microcosms, a
slight enrichment on δ13C
napththalene was detected, from -25.2‰ to -24.5‰ (enrichment of 0.7‰ ± 0.3‰)
after a biodegradation of approximately 65% of naphthalene (after 288 days).
For sulfate reducing microcosms, no significant changes were detected on the δ13C during naphthalene
biodegradation.