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Re: CO2 concentrations in water
- To: Aquatic-Plants at actwin_com
- Subject: Re: CO2 concentrations in water
- From: Paul Sears <psears at nrn1_NRCan.gc.ca>
- Date: Wed, 19 Dec 2001 16:18:28 -0500 (EST)
- In-Reply-To: <200112192048.fBJKm5Q26017 at actwin_com> from "Aquatic Plants Digest" at Dec 19, 2001 03:48:05 PM
> From: "Amy Ayukawa" <amyayukawa at hotmail_com>
> Subject: RE: Carbon Dioxide Concentrations in Water
> The recent discussion on CO2 concentrations in water remind me of a question
> I had when I read Diana Walstad's book recently.
> On page 93, she says, "The low productivity of submerged plants is not
> because there is less CO2 in water than in air. (On average, most natural
> waters have about three times more mg/l CO2 than air [8,9]). It is because
> CO2 diffuses so slowly in water (i.e., 10,000 times slower than air)."
> I included the last sentence of her quote just to complete her thought. What
> baffles me is the statement that "most natural waters have about three times
> more mg/l CO2 than air". I thought, and the recent APD discussion appears to
> confirm, that the concentration of CO2 in air was about 350 ppm
> while the
> concentration in sterile water is about 0.5 ppm.
By weight. Water is something like 800 times as dense as air.
> Even if the concentration
> in natural water is significantly higher due to decomposition of organic
> wastes, etc., I thought it got no higher than 3-5 ppm. Walstad's statement
> of "three times more mg/l CO2 than air"
i.e., both in weight per unit volume. _Neither_ of the others was
in those units, though mg/L is about the same as mg/kg for water.
>implies a CO2 concentration in
> natural water of over 1,000 ppm.
> Am I not understanding something or is Walstad wrong?
Just watch out for units!
Paul Sears Ottawa, Canada