Geochemical dynamics in sediments with deep oxygen penetration
M., Li J., and Katsev S. (submitted) Significant role of organic sulfur
in supporting sedimentary sulfate reduction in low-sulfate
environments. Geochim. Cosmochim. Acta.
- Katsev S. (2016) When large lakes respond fast: A parsimonious model for phosphorus dynamics. J. Great Lakes Res. (PDF)
S., & Crowe, S. A. (2015). Organic carbon burial efficiencies in
sediments: The power law of mineralization revisited. Geology, G36626-1 (PDF).
M., L. Moreau, J. Gordon, S. Quazi, C. Palermo, R. Fulthorpe, S.
Katsev, J. Bollmann, and A. Chesnyuk (2015) Geomicrobiology of Iron
Layers in the Sediment of Lake Superior. Aquat. Geochem.: 1-18.
J. and S. Katsev (2014) Nitrogen cycling in deeply oxygenated
sediments: Results in Lake Superior and implications for marine
sediments. Limnol. Oceanogr. 59, 465-481. (PDF)
et al. (2012) Carbon mineralization and oxygen dynamics in sediments
with deep oxygen penetration, Lake Superior. Limnology&Oceanography
75: 1634-1650 (PDF).
Li (2011) Diagenesis and sediment-water exchanges in organic-poor sediments of Lake Superior. M.Sc. Thesis. (PDF).
Kistner (2013) Reactivity of organic carbon in Lake Superior. M.Sc. project (PDF).
|NSF OCE: Transient diagenesis in organic-poor sediments: Lake Superior, $416,961, 2010-2013.
sediments of Lake Superior are characterized by extremely deep oxygen
penetration. Whereas in most lakes and coastal ocean oxygen penetrates
into sediments only by several mm, in Lake Superior we typically
measure oxygen penetrations of 3-12 cm
, and at one location even 27 cm!
This is unusual for lakes, but actually typical for the deep ocean. We
can therefore use Lake Superior as an easily accesible laboratory in
which to investigate processes that are important globally: rates of
organic carbon mineralization, fluctuations in the depth of the
sediment oxic/anoxic boundary, and dynamics of nutrient fluxes across
the sediment-water interface.
Our past work
has shown that sediments with deep penetration of oxygen are particularly sensitive to changes in external conditions. We have now recorded
seasonal changes in oxygen penetration of up to 2 cm in Lake Superior,
a process that affects the rates of nitrate removal and metals
Our results allow us
to compare the rates at which microbial communities process organic
material in freshwater vs. marine environments, which links to the
fundamental questions about the controls on reaction rates in aquatic
environments in the modern world, as well as in the Earth's early
||Below: The sediments of Lake Superior are characterized by extreme
lateral variability, with sediment properties varying strongly over as
little as hundreds of meters. The highly dynamic lake-bottom
environment leads to frequent migrations in the sediment oxic-anoxic
boundary and is recorded in priminent Fe-rich layers that are
ubiquitous in Lake Superior.
Lake Superior in comparison to the Ocean