Stable carbon isotope evidence of biodegradation zonation in a shallow jet-fuel contaminated aquifer
- Geological Survey, Columbia, SC (United States)
{delta}{sup 13}C values in dissolved inorganic carbon (DIC) ranged from -28 to +11.9% in a sandy, noncarbonate shallow aquifer contaminated with jet-fuel petroleum hydrocarbons. This range was observed over a 4-year study in shallow and deep monitoring wells and comprised {delta}{sup 13}C values representative of the aerobic and anaerobic microbial biodegradation of {sup 13}C-depleted jet fuel ({delta}{sup 13}C nearly equals -27%). The {delta}{sup 13}C DIC values were found to be influenced by the extent of rainwater infiltration of dissolved oxygen or sulfate or, conversely, by the absence of recharge, lack of dissolved oxygen or sulfate input to the aquifer, and the ensuing methanogenic conditions. After some recharge events delivered dissolved oxygen or sulfate to the shallow part of the aquifer, low to medium DIC {delta}{sup 13}C values were measured, and reflected biodegradation of {sup 13}C-depleted jet fuel under aerobic ({delta}{sup 13}C DIC nearly equals -26%) or sulfate-reducing ({delta}{sup 13}C DIC nearly equals -18%) conditions; the deeper part of the aquifer isolated from recharge was methanogenic and had higher {delta}{sup 13} DIC values. Conversely, when rainfall was absent and dissolved oxygen and sulfate concentrations were low in the aquifer, higher DIC {delta}{sup 13}C values were measured in both shallow and deep contaminated groundwater ({delta}{sup 13}C DIC up to +11.9%) where H{sub 2} concentrations indicated that the predominant terminal electron-accepting process was methanogenesis. 29 refs., 8 figs., 6 tabs.
- OSTI ID:
- 226679
- Journal Information:
- Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 4 Vol. 30; ISSN 0013-936X; ISSN ESTHAG
- Country of Publication:
- United States
- Language:
- English
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