Dataset: pigments_CN

Analysis Protocol:
Pigment analysis of filters was done on shipboard. Immediately after water samples were filtered, filter pads were transferred into 6 ml of 90% acetone and the pigment was extracted in a dark refrigerator for 24 hours. Filter pads were removed and the test tubes centrifuged just prior to reading the fluorescence. Fluorescence was read with a Turner Designs 10 AU fluorometer. Following the initial fluorescence reading, samples were acidified with ~0.2ml of HCl and reread. The fluorometer was calibrated using a spectrophotometer during each cruise using standard Chl-a derived from spinach. Chlorophyll-a and total phaeopigments were calculated from standard equations (Strickland and Parsons 1972).

Immediately after filtration, pre-ashed filters for carbon and nitrogen were folded in half, placed in glassine envelopes, dried at 60degC in a drying oven, then stored in a -20deg C freezer and redried just prior to analysis. Elemental analysis was performed using a Carlo-Erba ES1500 elemental analyzer within 6 months of collection. Background values were determined using blanks from the same filter supply as the samples, but without water filtration.