Data file describing the apparent quantum yield of photo-oxidation, photo-mineralization, and photo-stimulated microbial respiration of dissolved organic carbon in water samples collected at various sites near Toolik Lake on the North Slope of Alaska. A synthesis of the data presented here is published in Cory et al. 2013, PNAS 110:3429-3434, and in Cory et al. 2014, Science 345:925-928.
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The spectrum of the apparent quantum yield of DOC photo-photodegradation (Φλ) is the moles of product produced (relative to the dark control) per moles of photons absorbed by chromophoric dissolved organic matter (CDOM). The spectral dependence of the Φλ was assumed to decrease exponentially with increasing wavelength (Johannessen &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Miller 2001):
where parameters c (mol product mol‑1 photons) and d (nm-1) are positive constants. The parameters c (mol product per mol photons) and d (nm-1) in were determined using an unconstrained nonlinear optimization fminsearch function (Matlab 7.11.0) to give the best fit between the measured and calculated experimental values of photo-mineralization, partial photo-oxidation, or photo-stimulated bacterial respiration. We quantified an apparent quantum yield spectra (Φλ) for DOC photo-mineralization, partial photo-oxidation, and photo-stimulated bacterial respiration as the light vs. dark difference in photochemical DIC production, excess O2 consumption above photochemical DIC production, and bacterial respiration, respectively, from photo-exposure experiments described in Cory et al. 2013, 2014. Each Φλ was calculated by setting the experimentally measured product (e.g., mmol CO2 m-2 d-1 for example for photo-mineralization) as the left side of the equation below and solving for Φ,λ using the measured number of photons absorbed by CDOM in our experimental tubes during the photo-exposure (Qa,λ):
December 2014: Created this file, version .01
Version 2 Katie and Rose updated the decimal place of the data. 12Dec2014