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Aquatic laser fluorescence analyzer: field evaluation in the northern Gulf of Mexico

Chekalyuk, Alexander M.; Barnard, Andrew; Quigg, Antonietta; Hafez, Mark; Zhao, Yan

The new Aquatic Laser Fluorescence Analyzer (ALFA) provides spectral and temporal measurements of laser-stimulated emission (LSE) for assessment of phytoplankton pigments, community structure, photochemical efficiency (PY), and chromophoric dissolved organic matter (CDOM). The instrument was deployed in the Northern Gulf of Mexico to evaluate the ALFA analytical capabilities across the estuarine-marine gradient. The robust relationships between the pigment fluorescence and independent pigment measurements were used to validate the ALFA analytical algorithms and calibrate the instrument. The maximal PY magnitudes, PYm = PY(1-1.35·10−4PAR)−1, were estimated using the underway measurements of PY and photosynthetically active radiation (PAR). The chlorophyll (Chl) spatial patterns were calculated using the ratio of Chl fluorescence to PY to eliminate the effect of non-photochemical quenching on the underway Chl assessments. These measurements have provided rich information about spatial distributions of Chl, PYm, CDOM, and phytoplankton community structure, and demonstrated the utility of the ALFA instrument for oceanographic studies and bio-environmental surveys. The data suggest that the fluorescence measurements with 514 nm excitation can provide informative data for characterization of the CDOM-rich fresh, estuarine, and coastal aquatic environments.

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Also Published In

Title
Optics Express
DOI
https://doi.org/10.1364/OE.22.021641

More About This Work

Academic Units
Lamont-Doherty Earth Observatory
Biology and Paleo Environment
Published Here
October 7, 2014