[Coral-List] Ocean Acidification

Douglas Fenner douglasfenner at yahoo.com
Thu Jan 12 15:46:21 EST 2012

Thanks!!  I also note that it is my understanding that pure water is pH 7..0 only if it has not been in contact with air.  If it has been in contact with air it absorbs a little CO2, and since pure water is not buffered, it actually goes slightly below pH 7.0.  Sound familiar?  (so if you read the pH of distilled water but it has been in contact with the air, it will read below 7.0 pH.  Even distilled water is not really pure if it has been in contact with very clean air.  It will have N2, Oxygen, Argon, etc dissolved in it too, anything that is in the air.  The inert gases won't affect the pH.)       Cheers,  Doug


 From: "Booth, Charles E. (Biology)" <BOOTH at easternct.edu>
To: "coral-list at coral.aoml.noaa.gov" <coral-list at coral.aoml.noaa.gov> 
Sent: Thursday, January 12, 2012 5:28 AM
Subject: [Coral-List] Ocean Acidification

   Doug Fenner wrote (Wed, 11 Jan 2012 12:44:41 -0800 (PST):

   'As far as I can tell, the term "acidification" means that the pH is going
   down, not that the water is "acid."'

   I have been using 'acidification' in this context for decades in association
   with the titration of seawater samples with HCl to measure alkalinity. I add
   HCl to the water and the pH goes down, and if I add enough acid the pH falls
   below 7.0 (I titrate to pH 4.0; I would also note here that the neutral pH
   of pure water varies inversely with temperature, being 7.0 only at 25 C). I
   suspect I adopted this use from a chemistry book, or methods paper, or from
   talking with a chemist. I never encountered any opposition to my use of
   acidification until 'ocean acidification' came along and skeptics started
   arguing that it is an incorrect and misleading use of 'acidification,'
   apparently in an attempt to deny that ocean surface pH (and alkalinity) is
   decreasing measurably.

   Chuck Booth
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