Georges Bank Nutrient and Phytoplankton Chlorophyll Data from Univ. of Maine (GLOBEC Program)

Additional surface water samples were collected at positions between the regular stations (numbered >41; refer to Station Location Map for example). Phytoplankton chlorophyll a and phaeopigments were determined fluorometrically (Parsons et al., 1984). The extracted chlorophyll measurements involved collecting 100ml from all bottle samples taken at depths shallower than 60m, filtering through GF/F filters, and extracting in 90% acetone in a freezer for at least 12 hours.

The samples were analyzed at sea using a Turner Model 10 fluorometer. Water samples for DIN were filtered through 0.45 Millipore cellulose acetate membrane filters and then frozen immediately in 20ml acid-washed polyethylene scintillation vials by first placing the vials in a seawater-ice bath for approximately 10 minutes. Samples were analyzed in the lab following the cruise using a Technicon II 4-Channel Auto-Analyzer.

In addition to dissolved inorganic nutrients and chlorophyll, in 1999 we also analyzed samples for particulate organic carbon and nitrogen, dissolved organic nitrogen, and particulate and dissolved organic phosphorus. Results from the vertical profiles taken at each station can be viewed as contour plots (using Surfer Software, Golden Colorado) for 1997, 1998 and 1999. Plotted variables include Temperature and Salinity for the hydrographic data, Chlorophyll a for the pigment analyses and Nitrate plus Nitrite, Silicate, Ammonium and Phosphate for the inorganic nutrient analyses.

The hydrographic data were contoured only for the surface (2m). The pigment and inorganic nutrient concentrations were contoured for the surface (2m), 20 meter and 60 meter depths.