Dataset: McMurdo Sound chlorophyll
Deployment: McMurdo_CTDs_2012-2014

Small holes were drilled through the McMurdo Sound fast ice. A Niskin Bottle was deployed below the fast ice and water was collected just below the ice-water interface and at a pre-determined depth (Chlorophyll maximum) as determined by a fluorescence sensor on a CTD. Water samples from the Niskin bottles were collected in 4 L amber Nalgene bottles and then immediately stored in a dark cooler. Gloves were worn for sample collection and bottles and caps were rinsed three times before sample collection. The sample bottles were immediately processed as soon as they returned from the field. The collection bottle was gently swirled and 50 to 2000 mL were filtered under low vacuum onto a 25 mm GF/F filter. Filters were immediately placed in 13 mm borosilicate test tubes containing 7 mL 90% v/v HPLC grade acetone and extracted in the dark for 24 h at -20 degrees C. After extraction, fluorescence was measured with a Turner Designs 10 AU fluorometer before and after acidification. The fluorometer was calibrated at McMurdo Station at the beginning of the field season using Chlorophyll a standards from Sigma-Aldrich and rechecked using a solid standard from Turner Designs several times during the field season. Chlorophyll a was determined using the methods of Parsons et al. (1984).

Reference:
Parsons, T.R., Maita, Y., Lalli, C.M., 1984. A Manual of Chemical and Biological Methods for Seawater Analysis. Pergamon Press, New York, pp. 107–110.