Publication Date:
2019-07-17
Description:
Sulfate is the dominant terminal electron acceptor in
marine sediments. Sulfate reduction proceeds under anoxic
conditions and is supported by a variety of electron donors
(e.g. hydrogen, acetate, methane, propane, and butane), most
of which are supplied by the decomposition of sedimentary
organic matter. Consequently, a combination of primary
productivity and water column depth is often thought to
control sulfate reduction throughout most of the ocean’s
seafloor [1, 2]. However, global models of sulfate reduction
do not resolve the many different physical and ecological
parameters that are encountered on a global scale, and that
ultimately play a major role in driving local and regional
sulfate reduction rates. We sought to better determine sulfate
reduction rates on a global scale, irrespective of region or
location by 1) including sulfate profiles from diverse settings
and 2) compiling multiple geochemical parameters that are
relevant to sulfate reduction and can help discern the
magnitude of sulfate reduction rates. All available sulfate
concentration profiles from DSDP/ODP/IODP (to Exp. 312)
and additionally those in the database Pangaea
(www.pangaea.de) were compiled reaching a total 〉600 nonrepetitive
concentration profiles. Basic metadata describing
the cores was included, such as water depth and distance to
shore. Water column data such as minimum percent O2
saturation, bottom water O2, NO3
-, PO4
3-, and concentrations of
surface water chlorophyll a and POC [3, 4] were included as
additional variables that describe the biogeochemical setting
of the cores. All compiled data and concentration profiles
were applied to a training algorithm to estimate global sulfate
reduction rates. The result was the most precise depiction of
global sulfate reduction rates at the highest resolution to date.
Our model serves as a platform for the examination of
biogeochemical processes on the global scale and lets us
predict energetic constraints for microbial metabolism in the
subseafloor.
[1] Canfield (1991) AJOS 291, 177-188. [2] Middelburg et al.
(1997) DSR 44, 327-344. [3] Levitus & Boyer (1994) NOAA
Atlas NESDIS [4] NASA, Aqua-MODIS
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
notRev
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