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Re: E-M:/Re: Great Lakes Satellite Imagery



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Enviro-Mich message from "David J. Zaber" <dzaber@chorus.net>
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Hello,

Precipitates of calcium carbonate in  some aquatic ecosystems are naturally
occurring phenomena that are often found at locations where groundwater
enters surface waters and where plants are changing the chemistry of their
immediate surroundings.  One way the precipitate forms is when the pH rises
in the water.  Aquatic photosynthesis removes carbonic acid from solution,
thereby creating a more basic environment in the water immediately
surrounding the photosynthetic structures (plant leaves, stems, etc.).  This
results in precipitation of calcium carbonate, often known as marl.  That's
why one may only find marl on one side of a rock in a northern Michigan
trout stream; its the side with the algae.

One item to consider regarding the Lake Michigan photos.  Algal
proliferation may cause a sudden change in pH as photosynthesis removes weak
carbonic acids from the water. Thus, the precipitate may be inhanced by
phytoplankton photosynthesis.

Regards,

Dave Zaber

p.s.


----- Original Message -----
From: "Timothy Carpenter" <geodynamics@home.com>
To: <enviro-mich@great-lakes.net>
Sent: Friday, February 22, 2002 3:11 AM
Subject: E-M:/Re: Great Lakes Satellite Imagery


> -------------------------------------------------------------------------
> Enviro-Mich message from "Timothy Carpenter" <geodynamics@home.com>
> -------------------------------------------------------------------------
>
> The imagery of Lake Michigan ca. July through Sept 1999
>
(http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/NEW/USA/S1999205-1999250.LakeMi
> chigan.jpg) is referenced at several locations on the net, sometimes
> referring to "inorganic precipitation of calcium" and at others to "algae
> bloom". Based on a very incomplete search and correlation of dates, it
seems
> that early interpretations of the imagery leaned to the assumption that
the
> patterns were from algae. Later, the interpretations are leaning to
> precipitation of naturally occurring calcium carbonate ( see
> http://explorezone.com/snapshots/1999/09_24_whiting.htm ). It is
> particularly fascinating that the interpretation of calcium is based on an
> image from Sept 24, 1999. {As related previously, try downloading the
images
> then adjust the contrast and brightness with a photo editor to enhance the
> patterns in the water.}
>
> Calcium is a common mineral in the LP's soil and groundwater. Evidence of
it
> is found in the thick marl deposits at the bottom of peat bogs, in
> calcareous fens (wetlands below springs with a high alkalinity) and
> typically as "hard" water from domestic wells. Lime Lake, up near Traverse
> City, has a bed made of precipitated calcium carbonate. A major source of
> the calcium in our soil and groundwater is from limestone fragments
abraded
> and transported by glacial action from the Niagara Escarpment (
> http://www.escarpment.org/Geology/about_geology.htm ).
>
> Given no further information, I'd lean to expecting that the patterns in
> Lake Michigan are from the calcium rather than algae. To find out for sure
> what it is, I'll offer my services to sail up and down Lake Michigan
taking
> water samples all summer long -- if someone will supply the boat, grub,
crew
> and sunblock.
>
>
> -Tim-
>
> Please note that my @home.com address will be gone after the 28th -- it is
> replaced by geodynamics@comcast.net
>
>
>
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