Details:

Journal Title:
Marine Chemistry
Personal Author:
Masserini, R.T. ; Abbot, W. ; Hunt, H.R. ; Friden, E. ; Heil, C.A. ; ... More +
Masserini, R.T. ; Abbot, W. ; Hunt, H.R. ; Friden, E. ; Heil, C.A. ; Klass, S.M. Less -
NOAA Program & Office:
OMAO (Office of Marine and Aviation Operations)
Description:
Ammonium is the most energetically favorable form of inorganic nitrogen that phytoplankton can take up, and its availability often limits phytoplankton biomass. Recently, the majority of methods for quantification of ammonium at nanomolar concentrations have used the reaction between ammonium and o-phthaldialdehyde (OPA). Two different approaches have been employed. One involves gas diffusion of ammonia across a membrane. The other entails a more direct approach and utilizes sulfite as a reducing agent to form a fluorescent product. A benefit of the separation technique is that natural fluorescence of the samples does not yield a false positive signal, however membrane failure and clogging are challenging analytical problems. The direct reaction between the analyte and OPA, although devoid of problems associated with membranes, requires a correction for background fluorescence. This work presents the development of a reverse flow injection analysis (rFIA) method with automatic background fluorescence correction and a low detection limit, along with its application to measure underway ammonium concentrations in Tampa Bay during a bloom of the toxic dinoflagellate Karenia brevis with concurrent fish kills in June of 2021. During field testing elevated concentrations of ammonium were found to coincide with the largest number of observed floating dead fish and lethal K. brevis concentrations. The method employs a sulfite-formaldehyde reagent mixed with the sample into which an OPA reagent is injected and heated to activate fluorescence. Fluorescence of the sample is measured before the injection of OPA and at the peak of OPA injection, allowing for differentiation of the background fluorescence from the signal proportional to analyte. The detection limit and the limit of quantitation for this technique are 2.3 nM and 7.5 nM, respectively, and the coefficient of variation is 0.6% for replicate deionized water blanks (N = 10). Advantages of this method compared to techniques capable of both nanomolar detection of ammonium and improved accuracy via background fluorescence correction include a greater sample throughput, an increase in reported useful reagent lifetime, and the ability to quantify ammonium in coastal waters.
Keywords:
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Algal Blooms Ammonia Ammonium Fluorescence Fluorimetry Ocean Red Tide Seawater Ammonification Fluorometric Harmful Algae Karenia Brevis Nutrients
Source:
Marine Chemistry 245 (2022) 104158
DOI:
https://doi.org/10.1016/j.marchem.2022.104158
Format:
PDF
Document Type:
Journal Article
Funding:
Grant no. NA19NOS4780183
Place as Subject:
Tampa Bay (Fla.)
Rights Information:
Accepted Manuscript
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:19ff9a0e79bf12cd3bab762f0cfaf6ddeadae558a18252f485360728b7c7d9e0
Download URL:
https://repository.library.noaa.gov/view/noaa/51008/noaa_51008_DS1.pdf
File Type:

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