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