Factors influencing methane distribution in Texas ground water
Academic Article
Overview
Research
Identity
Additional Document Info
Other
View All
Overview
abstract
AbstractTo determine the factors that influence the distribution of methane in Texas ground water, water samples were collected from 40 wells in eastcentral and central Texas aquifers. Among the chemical parameters examined, sulfate is most important in controlling methane distribution. Methane occurs in high concentration (>10 M) in eastcentral Texas only where sulfate concentration is low (<1 M), supporting the hypothesis that abundant microbial methane production does not begin until sulfate is depleted. Because water samples from central Texas are high in either oxygen (up to 172 M) or sulfate (up to 28.7 M), methane concentrations are low (<5 M) in these waters. A positive correlation between methane and sulfate in these waters indicates a different, perhaps thermogenic, origin for the trace methane.The 13C/12C ratios of dissolved methane ranged from 80%o to 21%o in eastcentral Texas and from 41.2%e to 8.5%e in central Texas. Low values of < 50%e in the eastcentral Texas ground water indicate a microbial origin for methane and are consistent with the observed sulfatemethane relationship; high 13C/12C ratios of > 31%e likely result from bacterial methane oxidation. Similarly, methane with high 13C/12C ratios in central Texas may reflect partial oxidation of the methane pool. Overall, water samples from both regions show a positive correlation between sulfate concentration and the 13C/12C ratio of methane, suggesting that methane oxidation may be associated with sulfate reduction in Texas ground water.
