Date: Thu Nov 27 2003 - 03:39:05 EST
I wrote: > >> Technical point: If organisms take CaCO3 out of solution, then
> more CaCO3 will go into solution, where water contacts limestone
> (LS), and thereby allow additional organisms to take additional
> CaCO3 out of solution. This process can go on in principle until
> the oceans are saturated with such organisms (whatever that means).
> But as soon as they die, their skeletons will be available to
> contribute to the CaCO3 in solution.<<
>
Bivalve commented: It's a bit more complicated than that. Dissolved carbonate is in
> equilibrium with bicarbonate, carbonic acid, and dissolved carbon
> dioxide. Thus, pH and carbon dioxide concentrations have major
> impacts on the amount of carbonate available to organisms to
> precipitate.
Dave added: There is another complication. My /Van Nostrand's Scientific
Encyclopedia/ lists 404 g per metric ton of Ca in sea water, and 27.6 of
C. As I calculate it, if all the C were in CaCO3, that would require only
about 92 g of Ca out of the 404. So most of the Ca must be in other
states. Of course, one expects the compounds in solution to be primarily
in the form of ions. So the assumption of lime in/lime out bears no
relation to reality.
Right, the actual equilibria are no doubt very complicated; but the basic question (in my mind, not Glenn's) had to do with how many marine organisms with skeletons made of CaCO3 could be formed out of seawater. If you limit your system to a finite quantity of seawater in a container that doesn't interact with seawater, then the number of organisms would be limited by the amount of CaCO3 already dissolved in the seawater inside your container. Something like that is what I understood to be Glenn's original model when he said, "Today we have huge areas of the sea floor which are limestone, but the ocean waters can only hold tiny amounts. That is the limitation on the growth of calcium based organisms."
My "technical point" in essence was that seawater in oceans does interact with its container, so that the limit Glenn referred to would not strictly apply. The real world limit would depend on lots of stuff I know little or nothing about. I referred to it as "the oceans [becoming] saturated with such organisms (whatever that means)." (I'll leave the details to you guys. )
The point was that, as long as the organisms remain alive, they have taken both Ca and CO3 out of solution, and in one way or another that allows more Ca and CO3 ions to arrive on the scene and provide essential nutrients for new organisms, so that in principle the population of new, living organisms should not be limited by the initial amount of CaCO3 in the water.
I was touching on the problem of how many such organisms could be alive at any one time. That might be relevant to a YEC trying to defend a model based on Noah's flood. Glenn's primary concern, as he made clear in his post of 11-26, was how you could get massive piles of those organisms' skeletons on the seafloor. You do this, he says, by depositing new lime in the ocean by way of fresh-water sources over extended periods of time. Sounds plausible.
Don
