Abstract

LESSER-CARRILLO, Luis E.. Application of environmental isotopes to determine the biodegradation of organic compounds. Tecnol. cienc. agua [online]. 2015, vol.6, n.5, pp.123-129. ISSN 2007-2422.

Microcosm experiments were conducted to determine the fractionation of stable carbon isotopes during naphthalene biodegradation. The experiments were developed under aerobic and anaerobic conditions (sulfate-amended, nitrate-amended and unamended) and with sterile controls. The liquid phase was analyzed to determine the carbon concentration and stable carbon isotopes of the naphthalene. The aerobic microcosms showed that naphthalene aerobically biodegraded in less than 60 hours. The d¹³C increased from -25.5 to -25.1‰ (enrichment of 0.4 ± 0.08‰) in only one sample, in which 95% of naphthalene was biodegraded. After 288 days, the anaerobic microcosms showed a naphthalene consumption of 30, 50 and 60% on average for the unamended, NO₃^- amended and SO₄⁼ amended microcosms, respectively, relative to sterile controls. Under denitrifying conditions, d¹³C increased from -25.2 to -23.9‰ (enrichment of 1.3 ± 0.3‰) after a 95% biodegradation of naphthalene. The unamended microcosms demonstrated a slight enrichment (0.7 ± 0.3‰) of d13C from -25.2 to -24.5‰ after a biodegradation of 65% (after 288 days). For microcosms with SO₄⁼ reduction conditions, no significant changes were detected in the d¹³C of naphthalene during biodegradation.

Keywords : Naphthalene; isotope; fractionation; biodegradation; aerobic; anaerobic.

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