i dont know the exact chemistry but i know the presence of salt generally reduces solubility of other dissolved substances....
It is due to the fact that the water that "would" be dissolving the gasses/other substances has a higher affinity for ionic substances than for molecular substances (check that that statement is true before you use it
) and will therefore bind (dissolve/solvate) to the ions rather than "holding onto" (dissolve/solvate) the other molecules - in this case, gasses.
"salting out" is used in organic chem to force slightly soluble molecules (including seperating miscable liquids) out of aqueous solutions into either non polar layers or to simply crystallise and precipitate out (similar to a recrystallisation except with salt helping)
for more info
google
organic+chemistry+salting+out
Chemistry+salting+out
extraction+salting+out
Regardless i dont think we need to know this. I dont even think salt's effect on solubility is even relevant for the shipwrecks module as any decrease in solubility due to dissolved ionic substances will be more than countered by pressure at depth which has the opposite effect (ie it raises solubility)
This is all even less relevant when talkiing about deap sea wrecks as there are generally no currents to oxygenate the deeper waters... down here SRB = Corrosion ,.. a small amount of "rusting" may occur due to the acidity made as a byproduct of SRB NOT from CO2
Re CO2 - the conc of this is too low to make any apreciable difference, but even if it did when CO2 dissolves it becomes a BUFFER rather than just an acid ...
ie CO2(g)<=>CO2(aq) CO2(aq) + H20 (L)-->H2CO3 (aq)<=>H^+(aq) + HCO3^-(aq) <=> H^+(aq) + CO3^2-(aq))
