Ecological Engineering
Group,
Department of Civil &
Environmental Engineering,
Application and Benefits of Hypolimnetic Oxygenation”
Summertime hypolimnetic anoxia, a
complete lack of dissolved oxygen
in
bottom waters, is a common phenomenon in productive lakes and
reservoirs. Anaerobic conditions in bottom waters result in
a number
of negative
ecological consequences including the hypolimnetic
accumulation of nutrients
(e.g., ammonia and orthophosphate) that
exacerbate
eutrophication, toxins (e.g., sulfide, ammonia, and
methylmercury) that impair aquatic biota, and reduced metals
(e.g., iron and manganese) that complicate potable water
treatment.
Hypolimnetic
anoxia also results in a loss of habitat for cold-water fish,
as well as pelagic
zooplankton seeking a dark daytime refuge to avoid
predation. Hypolimnetic
oxygenation is a relatively new management
technique that averts
hypolimnetic anoxia and its harmful consequences
by
oxygenating the hypolimnion using pure oxygen gas. This paper will
discuss a number of
issues related to hypolimnetic oxygenation including:
(1) advantages of hypolimnetic
oxygenation over more traditional lake
management strategies (e.g., destratification, aeration),
(2) the three main types of
hypolimnetic oxygenation systems currently
in use (bubble plume,
linear diffuser and submerged contact chamber),
(3) oxygenation design
considerations including the phenomena of
“induced oxygen demand” - the increase in observed oxygen
demand
after system startup,
(4) the multiple water quality
benefits of oxygenation,
(5) two regional case studies of submerged
contact chamber
oxygenation in
(6) additional potential
applications of oxygenation technology including
targeted oxygenation in
accumulation in lake biota, and oxygenation at trout
aquaculture
facilities in