Fig. 10 - This may look like a mess, but the biggest solution in the world is of course the ocean, and here's a bird's-eye view of the acid-base chemistry of seawater.

Note especially that

• the only really important pH on this graph is 8, the approximate pH of the natural ocean.
• The pH of the ocean is controlled mainly by the carbonate system because it is more concentrated than the two minor buffering systems, borate and silicate.
• The surface waters of the ocean are everywhere supersaturated in calcium bicarbonate and in CO₂ , as shown by the dotted curves (the "ss[CO₂ ]" label is the illegible one-- sorry!)
• Ion-pair complexes such as MgOH⁺ are significant species in seawater; there are many others.