[Coral-List] Use of mercuric chloride for TA measurements

Thomas Krueger thomas.krueger at epfl.ch
Thu Jun 29 06:50:33 EDT 2017


I was wondering, how mandatory the use of mercuric chloride is for 
storing seawater samples for later total alkalinity (TA) measurements? 
There are a range of papers on coral calcification that do no explicitly 
mention the use of mercuric chloride in preserving the water sample for 
later analysis. For our case, the water samples were taken from 
respiration chamber incubations that used 0.2 um filtered seawater, and 
the samples were stored in brown, borosilicate glass containers at 4°C 
for analysis of TA within 4 weeks. Do you think that the fundamental 
concern that biological activity might have altered the TA results is 
justified? All the used pH-values for the later CO2sys calculations were 
measured directly when taking the sample and not at the time the bottle 
was re-opened for the titration.

Thanks for your thoughts on this.



*Thomas Krueger */Postdoctoral Researcher/

Laboratory for Biological Geochemistry | École polytechnique fédérale de 
Lausanne (EPFL)

*P*: (+41) 21 69 38039

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