The geochemical evolution of low-molecular-weight organic acids derived from the degradation of petroleum contaminants in groundwater

Journal Article · Sat Jan 01 04:00:00 EST 1994 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(94)90511-8· OSTI ID:5217859

Cozzarelli, I M; Baedecker, M J; Eganhouse, R P ^[1]; Goerlitz, D F ^[2]

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1. Geological Survey, Reston VA (United States)
2. Geological Survey, Menlo Park, CA (United States)

The geochemical evolution of low-molecular-weight organic acids in groundwater downgradient from a crude-oil spill near Bemidji, Minnesota, was studied over a five year period (1986-90). The organic acids are metabolic intermediates of the degradation of components of the crude oil and are structurally related to hydrocarbon precursors. The concentrations of organic acids, particularly aliphatic acids, increase as the microbial alteration of hydrocarbons progresses. The organic-acid pool changes in composition and concentration over time and in space as the degradation processes shift from Fe(III) reduction to methanogenesis. Over time, the aquifer system evolves into one in which the groundwater contains more oxidized products of hydrocarbon degradation and the reduced forms of iron, manganese, and nitrogen. Laboratory microcosm experiments with aquifer material support the hypothesis that organic acids observed in the groundwater originate from the microbial degradation of aromatic hydrocarbons under anoxic conditions. The geochemistry of two other shallow aquifers in coastal plain sediments, one contaminated with creosote waste and the other with gasoline, were compared to the Bemidji site. The geochemical evolution of the low-molecular-weight organic acid pool in these systems is controlled, in part, by the presence of electron acceptors available for microbially mediated electron-transfer reactions. The depletion of electron acceptors in aquifers leads to the accumulation of aliphatic organic acids in anoxic groundwater.

• OSTI ID: 5217859
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 58:2; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
ACETIC ACID
ANAEROBIC CONDITIONS
AROMATICS
BENZOIC ACID
BIODEGRADATION
BIOSYNTHESIS
BUTYRIC ACID
CARBOXYLIC ACIDS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
DECOMPOSITION
ENERGY SOURCES
FOSSIL FUELS
FUELS
GROUND WATER
HEPTANOIC ACID
HYDROGEN COMPOUNDS
ISOVALERIC ACID
MONOCARBOXYLIC ACIDS
OIL SPILLS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PETROLEUM
POLLUTANTS
QUANTITATIVE CHEMICAL ANALYSIS
SYNTHESIS
VALERIC ACID
WATER