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INTRODUCTION
BIOGEOCHEMICAL
MAPS
BIOGEOCHEMICAL
PROFILES
SEDIMENT
ISOTHERMS
REFERENCES
AND ACKNOWLEDGEMENTS
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This website
provides ready access to geochemical and geophysical information to help
scientists assess the kinds of microbial communities and the levels and
kinds of microbial activity that are likely to exist in marine sediments
of different regions at different depths beneath the seafloor. This information
is also intended to help scientists identify chemical species and geological
regimes that should be examined in greater detail to more fully characterize
the geochemical environment and activity of microbes in sediments throughout
the world’s ocean basins.
The
Biogeochemical Database
Sediment biogeochemical
data may be used to predict burial depths and geographic regions in which
specific microbial communities, such as communities with active sulfate
reducers, MnO2 reducers, methanogenic microbes, or anaerobic methanotrophs,
can be most effectively targeted and recovered. Biogeochemical data in
this website include porewater concentrations of SO4-2 and NO3- (electron
acceptors) and dissolved manganese and iron (inferred to be products of
MnO2 and Fe-oxide reduction). The compiled data also include headspace
concentrations of CH4 (a product of methanogenesis and an electron donor).
These biogeochemical data are presented in two forms on the website: as
profiles from individual sites, automatically drafted on demand, and in
global maps that integrate data from the entire database. Some of these
maps show the global distribution of Ocean Drilling Program (ODP) and
Deep Sea Drilling Project (DSDP) sites where concentrations of the individual
chemical species were measured in porewater samples. Additional SO4-2
and CH4 maps exhibit global patterns of edited concentration data.
The Geothermal Database
The website also
contains global maps of estimated sediment depths for several isotherms
that may be useful for studies of subseafloor microbial communities
(30°C, 60°C, 90°C, and 120°C isotherms). Because there
are distinct temperature limits for different microbial classes, estimates
of subsurface temperatures may be useful for identifying drilling targets
of special microbiological interest. For example, they may be used to
predict geographic regions and sediment depths where active microbial
communities in deep-sea sediments might be mesophilic, thermophilic,
or hyperthermophilic. They might also be used to inform the search for
anaerobic communities strongly supported by chemolithotrophy and the
search for the upper thermal limit to life in deeply buried deep-sea
sediments. |
