Water samples were collected from CTD Niskin bottles. Water samples for HPLC analyses were taken from one Niskin bottle per cast-depth combination included in the dataset. Note that the niskin_sampled column indicates which Niskin bottle the HPLC sample was taken from. The niskins_fired column indicates all Niskin bottle numbers fired at the specified depth, though the HPLC sample was taken from only one of those bottles.
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Chlorophyll and accessory pigment composition was analyzed by high performance liquid chromatography (HPLC; Agilent 1100). Culture aliquots were filtered on Whatmann GF/F filters, flash frozen in liquid nitrogen, and stored at -80\u00b0C until analysis. Just prior to analysis, pigments were extracted overnight in acetone at -20\u00b0C. The following day extracted pigments were centrifuged and measured using a gradient elution method (DiTullio and Geesey, 2003), a modification of the Zapata et al 2000 method. Chromatographic separation was performed using a Waters C8 symmetry column, photodiode array and fluorescence detectors. The internal standard, \u03b2-Apo-8-carotenal-trans standard (Fluka Chemical Corp., USA) was added to extracted pigments as a peak reference. Individual pigment peaks were quantified with Chemstation software (revision B.03.01, Agilent) and our pigment action spectra library calibrated using pigment standards from DHI LABS (Hoersholm, Denmark) and in-house purifications of non-commercially available pigments. Coefficient of variation among replicate HPLC injections is < 3% and our limit of detection is approximately 1 ng L-1.
Response factors for pigments were performed using dilutions of calibration standards. Full details of data processing and methods used can be found in:
\nDiTullio, G. R. & Geesey, M. E. (2002) Photosynthetic pigments in marine algae and bacteria. In: BITTON, G. (ed.) The Encyclopedia of Environmental Microbiology. New York: John Wiley & Sons Inc.
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BCO-DMO Processing Notes:
\n- Modified parameter names to conform to BCO-DMO conventions;
\n- Blanks (missing data) replaced with \"nd\" meaning \"no data\";
\n- Separated the original \"niskin\" column into two columns: \"niskin_sampled\" and \"niskins_fired\";
\n- Converted original longitude values provided as positive degrees West to negative degrees East;
\n- Added ISO_DateTime_UTC column from original date_gmt and time_gmt fields;
\n- Transposed data to convert columns containing pigment concentrations into rows.