Ocean Acidification: Can CO2 Release & pH Decrease Simultaneously?

[Studiot]

Note that my approach - solving full system of equations for all variables - yielded immediately all concentrations of all ions involved. Also note that it yielded the same result you got, even if you have claimed that it is inadequate.

Thanks for the independant check by more sophisticated means. I see your calculator required 17 iterations.
I don't remember claiming any end result as inadequate. But I am also conscious of the length of the path yet to be trod. I am just trying to build up from small beginnings in simple steps.
The issue is really not one of "is the model as complex and comprhensive as possible?", but
"is it up to supplying the desired results correctly?"
You seem to have confirmed that all these sundry august institutions have got is right, so the next step is to examine the effect of three big inputs.

1) The effect of acidifying gases in the atmosphere
2) The effect of biologcal agents
3) The effect of chemicals in solution, other than calcium carbonate



Please remember that this is not 'my theory'. I lay no claim to originality. This is the Earth Sciences part of the forum so I am aware that many readers will not be chemists (nor am I actually) so I am trying to carry out forum policy and expound and explain conventional thinking in the subject area.
By conventional thinking I mean the equations and theory you will find in publications and papers from leading Oceanographic organisations around the globe. My sources in particular come from the National Oceanographic Centre, Southampton, NOAH and the Woods Hole Institute, University of Ontariao Environmental Science Unit and the institution where I was a postgrad many centuries ago and then called the Plymouth School of Maritime Studies ( now Plymouth University).
So I am trying to help others, mostly environmentalists, understand the output of learned institutions.

But now I understand even less, as if you are solving system using numerical approach, why do you start with approximations, instead of solving full system in a general way?

One form of numerical approach is to have a seed approximation for at least one of the variables. This is used to calculate approximations for other variables, which are then recycled to improve the first approximation.

You may not be aware that Oceanographers have several definitions of ocean alkalinity,
Here is the relevant one to our equations, the carbonate alkalinity

{A_{carb}} = \left[ {HCO_{_3}^ - } \right] + 2\left[ {CO_3^{2 - }} \right]

Using our equations it is possible to explain the apparent paradox that the pH can simultaneously decrease with whilst the alkalinity increases. Obviously not indefinitely though.

 

[sylas]

Thanks for the independant check by more sophisticated means. I see your calculator required 17 iterations.
I don't remember claiming any end result as inadequate. ...

What you claimed is that Borek's method was inadequate, back in [post=2696999]msg #54[/post].

If the interest is still there in this subject I will post the calculations. They are of interest because they show the inadequacy of Borek's concatenation method and the reason for not combining the constituent reactions.

Borek is pointing out that in fact, he is using the general method; which is not "inadequate" at all.

You may not be aware that Oceanographers have several definitions of ocean alkalinity

Or maybe he is. Borek is (I believe) our most competent and well informed science advisor on chemistry. I'm trying to say this gently... but frankly it is getting a bit old your trying to imply Borek is in need of your help to understand the relevant chemistry. Just make the points you feel relevant, and no doubt we'll all learn something working through the discussion.

Cheers -- sylas

 

[Borek]

I will post the calculations. They are of interest because they show the inadequacy of Borek's concatenation method and the reason for not combining the constituent reactions.

I don't remember claiming any end result as inadequate.

Sorry, but you have lost me here. You claimed you will show inadequacy of my method but now you say that it can produce adequate end results?

Note that I don't claim originality of the method I present either. This approach is about as old as modern chemistry. And while there are many simplified approaches that stem out from the general model, and while many of these simplified models are used in different branches of the scientific world (be it Earth sciences, biology, agricultural sciences and so on), they are just that - simplified approach to partial problems. Simplified - which means they work only in a limited range of concentrations/conditions. That was the price paid to make them usable before computing power became so cheap.

At the moment any PC with GHz processor (have you seen a weaker one in the last few years?) have enough power to calculate equilibrium of system like sea water in a reasonable time using general approach (given you have enough data about all equilibria present, but that's another can of worms). See for example

http://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/

(they have modified the model to reduce number of variables and make calculations faster, but it is still the same method, based on all equilibria and mass/charge balances). There are also other programs like MINTEQA and MINEQL (here I am quoting names from memory, so I can be off) all based on the same general approach.

Edit: Sylas answered while I was editing the post, it took me much longer than expected because of several phone calls in the meantime.

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methods

 

[Borek]

Borek is (I believe) our most competent and well informed science advisor on chemistry.

I am not, but thank you