Fluorescence .dat files: columns are excitation wavelength (nm) and rows are emission wavelength (nm). The value in each cell is the blank corrected and normalized (by fluorescence of a quinine sulfate standard, described in detail below) fluorescence for each exciation/emission pair.
Blank corrected EEM spectra were corrected for any inner filter effects using the Aqualog software. All spectra were normalized to the fluorescence of a 1 ppb quinine sulfate (QS) standard in 0.1 N HClO4 (STARNA) at excitation 347.5 nm, corrected for sample integration time. A 0.1 N HClO4 solution (STARNA) was used as the QS blank. Therefore all EEM spectra are reported in QS units (QSU). Rayleigh scattering signals were removed from EEM spectra using the Matlab ® (version 2015a) routine outlined previously (Zepp et al. 2004 doi: 10.1016/j.marchem.2004.02.006).
The following additional parameters were also calculated:
Apeak: intensity and location of maximum in the "A" region (ex/em <260 nm/400 – 460 nm) in (intensity x ex. location x em. location) (Coble et al. 1996)
Cpeak: intensity and location of maximum in the "C" region (ex/em 320 – 360 nm/420 – 460 nm) in (intensity x ex. location x em. location) (Coble et al. 1996)
Fluorescence Index, FI Ratio of fluorescence emission at 470 nm / 520 nm at 370 nm excitation Indicative of DOM source (McKnight et al. 2001)
normalized HIX (nHIX) Integrated emission from 435-480 / (300-345 + 435-480) nm at 254 nm excitation Indicative of DOM source and processing (Ohno 2002a)
Biological Index (BIX) Ratio of the fluorescence intensity at 380 nm to 430 nm at 310 nm excitation Indication of recent microbial activity (Huguet et al. 2009)
BCO-DMO Blog
©2024 Biological and Chemical Oceanography Data Management Office.
