QUOTE Dissolved gas supersaturation (DGS) is a condition
that occurs when the partial pressures of
atmospheric gases in solution exceed their
respective partial pressures in the atmosphere. Individual
atmospheric dissolved gases (oxygen, nitrogen, and trace
gases such as argon and carbon dioxide) can often be
supersaturated without adverse effects on aquatic and
marine organisms. When the sum of the partial pressures
of all dissolved gases exceeds atmospheric pressure,
however, there is the potential for gas bubbles to develop
in water and in the aquatic organisms that inhabit the
water. This causes a condition known as gas bubble
trauma (GBT).
DGS can result from various anthropogenic and natural
causes. Hydroelectric and impoundment dams are known
to cause high levels of DGS. Other sources include warm
water discharges from cooling facilities (e.g., nuclear and
fossil fuel powered generating plants), oxygen production
by aquatic plants (enhanced by nutrients associated with
industrial effluents, municipal discharges, and agricultural
runoff), natural solar heating of water bodies,
injection of
air into pumping systems, supplemental oxygen in
hatcheries, and air lift reaeration systems.
UNQUOTE
Bolding is mine for emphasis. This text is an excerpt from the
Canadian Water Quality Guidelines for the Protection
of Aquatic Life
The document highlights a number of findings relating to GBT-caused mortality rates in both fresh water and marine fishes and invertebrates. It also provides guidelines for maximum allowable dissolved gas tension as a function of water depth and partial pressure of dissolved oxygen (mm Hg).
While beyond the scope of my expertise, it would be wonderful if we could do the measurements discussed in the Guidelines to see where we stand with respect to the injection of nano/micro/nanomicro bubbles into our aquaria.
It would be one issue surrounding the bubble talk that we could put to bed.
