[Coral-List] re: ammonia levels in aquarium waters

[Szmant, Alina]

Hello All:
 
Chris D'Elia had the courtesy of correcting my late-night math (I'm blaming it on vacation brain), and yes, the conversion of 20 ppm to atomic units should have been 1.4 mM not uM.  I guess I wasn't thinking clearly when I replied to the original message.  14 mM is a high concentration even for northern latitude coastal waters.  I have never tested a concentration that high on anything other than Gambusia (water samples from land fills and nearby polluted mangrove swamps), but I would guess this NH4 level would be quite harmful to most organisms.  That level of ammonium would only be expected to be found in porewaters of highly anoxic sediments with high organic loads (e.g. in mangrove swamps; places like the major estuaries such as Narragansett Bay etc).  The highest concentrations in surface waters I have ever measured were in mangrove lagoons and were in the 5-10 uM range (= 0.07 to 0.14 ppm).  
 
Sorry for any confusion I may have caused!
 
Alina Szmant
 
*******************************************************************
Dr. Alina M. Szmant
Coral Reef Research Group
UNCW-Center for Marine Science 
5600 Marvin K. Moss Ln
Wilmington NC 28409
Tel: (910)962-2362 & Fax:  (910)962-2410
Cell:  (910)200-3913
email:  szmanta at uncw.edu
Web Page:  http://people.uncw.edu/szmanta
******************************************************************

________________________________

From: coral-list-bounces at coral.aoml.noaa.gov on behalf of Charles Booth
Sent: Wed 12/28/2005 12:53 PM
To: coral-list at coral.aoml.noaa.gov
Subject: [Coral-List] re: ammonia levels in aquarium waters



Regarding the potential impact of 20 ppm NH4+ on corals growing in aquaria,
Alina Szmant wrote:

 20 ppm when you divide by 14 (atomic weight of N) = 1.4 uM NH4+

Math has always been one of my weak points, but 20 ppm = 20 mg per kg, (or
ca. 20 mg per L). So, dividing by 14 would give a value of 1.4 millimolar
(mM) NH4+ - not 1.4 micromolar (uM)?  And if the original value of 20 ppm
referred to the concentration of ammonium ion, not ammonium nitrogen (I
don¹t recall it specifying either way), the calculation should be:  20 ppm
divided by 18 (formula or molecular weight of NH4+) = 1.11 mM.
If I have made a mistake here, I apologize in advance.

Chuck Booth
*   *   *   *   *   *   *
Dr. Charles E. Booth
Dept. of Biology
Eastern Connecticut State University
Willimantic, CT  06226

Ph: 860-465-5260
Email: booth at easternct.edu
FAX:  860-465-5213

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