Below the calcium compensation depth cold temperature and high pressure dissolve more carbon dioxide gas producing carbonic acid. why isn't deep water more acidic? a) calcium carbonate (caco3) precipitates removing carbonate ions (co,"), which combine with hydrogen ions (h) decreasing ph b) calcium carbonate (caco3) shells dissolve releasing carbonate ions (co ), which combine with hydrogen ions (h') increasing ph. c) calcium carbonate (caco3) precipitates releasing carbonate ions (co3), which combine with hydrogen ions (h') increasing ph. d) deep water is more acidic