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Fri, 11 Jul 1997 17:37:57 -0400 |
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Dear Isogeochemists,
Is anyone aware of any D/H analyses of bacterial hydrogen or hydrogen
liberated by the interaction of acids with metals? Or has anyone ever
encountered high hydrogen concentrations in soil gas? In the analysis of
some soil gas samples as part of an environmental assessment, we encountered
soil gases with hydrogen concentrations as high as almost 6%. The samples
also contain several percent CO2 with trace levels of methane(~300ppm),
ethane, ethylene, and propane(~30ppm each). The remainder of the samples
are air with some oxygen depletion.
We are interested in determining the source of the hydrogen. The only two
explanations I have been able to come up with are that either it is of
bacterial origin (organic decomposition) or that it is from some acid-metal
reaction. We measured the D/H of the hydrogen on a couple samples and got
values of -530 and -630 (relative to SMOW). These light values would seem
to me to suggest a bacterial origin, but I've never heard of hydrogen
concentrations this high before in bacterial gases. I always thought that
high hydrogen poisoned the bacteria that produce hydrogen. Also, if it is
bacterial, it must have been anaerobic and the air must be a contaminant.
If we calculate air-free compositions, the hydrogen concentrations are over
8%.
If anyone has any information on the isotopic composition of hydrogen from
different sources I would greatly appreciate hearing from you. Or, if
anyone has a good explanation for high hydrogen in soil gas, I'd also be
interested in hearing those ideas. Thanks for your help.
Dennis Coleman
Isotech Laboratories, Inc.
1308 Parkland Court
Champaign, IL 61821
phone 217/398-3490
fax 217/398-3493
email [log in to unmask]
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