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Phenol
---------- Forwarded message ----------
From: Stephen.Pushak at saudan_HAC.COM
Subject: Phenol
To: aquatic-plants at actwin_com
Date: Sun, 09 Mar 1997 5:25:11 PST
Cc: nfrank at mindspring_com
> From: Craig Bingman <cbingman at netcom_com>
> > Where does phenol come from?
>
> There are many phenolic groups in lignin and its decomposition products.
> Lignin is found in terrestrial plants. Very loosely, it is like glue
> that holds cellulose bundles together. Sort of the collagen of
> terrestrial plants.
Cellose is the rigid material in macrophytes or what we think of as
regular plants. The decay of plant tissues, even before the leaves
detach from the stem, releases phenol and phenolic compounds in very
low concentrations. Phenol inhibits algaes but it also has an inhibitory
effect on plants to a lesser degree. It is thought that some plants
release phenols and other chemicals as a form of chemical warfare
called allelopathy in order to compete with algae and other plants.
Straw or hay has been used to clear algae or duckweed from ponds;
it works extremely well! There are dozens (perhaps more) of phenolic
compounds including caffeic acid (in caffeine), cinnamic acid
(cinnamin) and vanillic acid (you guessed, vanilla) which are known
to have powerful allelopathic effects. Does this give
you any new ideas for treating blue-green cyano-bacteria?
One theory to explain why new tanks have more algae problems than
established tanks is that it takes a while to build up a number of
allelopathic compounds in the tank. These are thought to act
synergistically where their combined effect is greater than the
sum of their individual effects.
Tannic acid and the humic acids (an extremely diverse class of organic
compounds) are released by peat or humic soils and these may be useful
for inhibiting many types of bacteria including cyano-bacteria and
are fairly benign for your fish. Bacteria themselves engage in all
out chemical warfare with each other and those compounds can be fairly
lethal to us (food poisoning) or useful (antibiotics). This is why
too much uneaten food or a dead fish in the aquarium can be so toxic;
this provides a fertile environment for their growth.
There are a lot of toxic decomposition byproducts from the breakdown
of organic material especially animal tissue; many of these are products
of bacteria. After a fish mortality, it might be a good plan to use
activated carbon filtration but as a general strategy, continuous
carbon filtration may be counter productive since it will remove humic
acids which inhibit bacteria. Also humic material and detritus in
the aquarium also rapidly absorb and detoxify many chemicals including
zinc, aluminum and copper! Translation: a proper soil substrate is
healthier than a "sterile" substrate. Humic and organic material in
soils also performs an extremely important role in the complex system
which maintains a very stable pH in submerged soils of 6-6.5.
On the subject of rinsing a filter which has been turned off for more
than a day, this is probably a wise precaution. I suspect that the
majority of toxic bacterial products are from anaerobic bacteria
acting upon labile matter like uneaten food. This is an important
reason why I keep snails in all my aquariums. I believe there are
an important part of my artificial bio-systems. To prevent any
misunderstandings, I don't believe anaerobic bacteria acting upon
less labile materials such as detritus (the remains of plants) or
small amounts of carnivorous fish feces are a serious cause for
concern.
For further reading on allelopathy, take a look at TAG back issues
8-4, 8-5, 8-6 & 9-2 (Walstad); and some discussion in 5-4 (Krombholz).
Steve Pushak - spush at hcsd_hac.com - Vancouver, BC, Canada
There are no signposts in the sky to show a man has passed that way
before. There are no channels marked. The flier breaks each second
into new uncharted seas. - Anne Morrow Lindbergh