Marin and Phil,

As someone who studies surface water quality issues for a living, let me
clear up one or two issues surrounding the feeding of critters in the water.

First, any organic matter placed in the water will place a demand on the
available oxygen as it naturally decays due primarily to microbial activity.
Even if it is consumes by a carnivore, the excrement will have higher
organic content than normal in the diet and will still place a greater
oxygen demand than normal.  So it is not wise to 'dump' anything that is not
directly food (bait) for the critters.

That said, algae (or phytoplankton) do not consume organic matter nor do
they use oxygen in their growth phase.  In fact, just like plants and trees,
they consume carbon dioxide and give off oxygen.  Algal blooms can actually
produce saturated oxygen conditions.  Unfortunately, the phytoplankton will
eventually die and then consume oxygen when they decompose like the other
organic material.  Phytoplankton gets its carbon from the carbon dioxide and
requires other nutrients, primarily nitrogen and phosphorous.

As long as the water column contains sufficient oxygen everything goes along
pretty well.  When the water column gets stratified (doesn't mix from top to
bottom) then the lower levels can get depleted of oxygen.  Then other
microbes take over that can use sources other than oxygen to decompose
things.  This is termed 'anaerobic' and produces those lovely rotten egg
smells we have all experienced.  The anaerobic conditions can also lead to
the release of other nasty things form the sediments so it is quite a bad
condition.

Bill

Bill Fleenor, Ph.D.
Research Engineer

Double-Wide (under construction)

While we are on the subject of dumping things into the water, let me pose an
additional question for Bill and any others who wish to respond.

In the aftermath of Katrina, we are hearing terrible news about the contents
of the floodwaters in New Orleans.  I heard tonight that the Cholera
bacteria and e-coli are present in those waters, along with decomposing
bodies and foodstuffs.  When one adds the chemical compounds, including
petrochemicals, that are clearly evident even to the untrained eye, it is
apparent that New Orleans is flooded with a toxic cocktail that is not only
deadly to humans, but to the environment as a whole.

The current plan (they have already started) is to pump the water out of the
city into the canals leading to Lake Ponchartrain and the Mississippi River.
That will transfer the toxic waste into the delta wetlands, and into the
Gulf.  To my mind this solution, while clearly the primary (and maybe only)
option for removal of water from the city, will have a significant and
lasting detrimental effect on the ecology of the Gulf Coast.

Is there no other way to deal with this crisis?  Would it not be more
reasonable to somehow divert the outflow from the pumps for treatment of
some sort before it is discharged into the local environment?  I hope I am
not the only person concerned about the lasting effects that the 12 feet of
stagnant, toxic sewage currently in New Orleans could cause to sea life,
indigenous animal life and humans living in Mississippi, Louisiana, Alabama,
and the surrounding states?  If the current solution is expected to take
more than 2 months, it's certainly more critical than worrying about whether
one should toss a banana peel or peach pit overboard.  It also appears to me
that the discharge of untreated waste from vessels is prohibited within the
three-mile limit.  There is a dichotomy here that I do not understand.

Bob Davies
Toronto