Seasonal variations in ebullitive flux and carbon isotopic composition of methane in a tidal freshwater estuary

Journal Article · Thu Sep 01 04:00:00 EDT 1988 · Global Biogeochemical Cycles; (USA)

DOI:https://doi.org/10.1029/GB002i003p00289· OSTI ID:6656256

Chanton, J P; Martens, C S ^[1]

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1. Florida State Univ., Tallahassee (USA)

Methane carbon isotopic composition ranged from {minus}76.9 to {minus}62.6{per thousand} in a tidal freshwater estuary (the White Oak River, North Carolina, US) with the site specific seasonal variations ranging from 6 to 10{per thousand}. During warmer months, tidally induced bubble ebullition actively transported this methane to the atmosphere. At two sites, these seasonally varying fluxes ranged from 1.2 + or{minus}0.3 to 1.3 + or{minus}0.3 mol CH{sub 4}/sq m/yr with flux-weighted average isotopic compositions at two sites of {minus}66.3 + or{minus}0.4 and {minus}69.5 + or{minus}0.6{per thousand}. The carbon isotopic composition of naturally released bubbles was shown to be indistinguishable from the sedimentary methane bubble reservoir at three sites, leading to the conclusion that isotopic fractionation did not occur during the ebullition of methane. The hypothesis was developed that ebullitive methane fluxes are depleted in C{sup 13}-CH{sub 4} relative to fluxes transported via molecular diffusion or through plants, as zones of C{sup 13}-enriching microbial methane oxidation are bypassed.

• OSTI ID: 6656256
• Journal Information: Global Biogeochemical Cycles; (USA), Journal Name: Global Biogeochemical Cycles; (USA) Vol. 2:3; ISSN GBCYE; ISSN 0886-6236
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
560300 -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKANES
BIODEGRADATION
BIOGEOCHEMISTRY
CARBON 13
CARBON ISOTOPES
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
ECOLOGICAL CONCENTRATION
ENVIRONMENTAL TRANSPORT
ESTUARIES
EVEN-ODD NUCLEI
FEDERAL REGION IV
FRESH WATER
GEOCHEMISTRY
HYDROCARBONS
HYDROGEN COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MASS TRANSFER
METHANE
MICROORGANISMS
NORTH AMERICA
NORTH CAROLINA
NUCLEI
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
SEASONAL VARIATIONS
STABLE ISOTOPES
SURFACE WATERS
USA
VARIATIONS
WATER