Carbon uptake rate calculated for CTD water samples during POLARSTERN cruise ARK-XXVII/3 (IceArc) in 2012


Net Primary Production was measured using the 14C uptake method with minor modifications. Seawater samples were spiked with 0.1µCi ml-1 of 14C labelled sodium bicarbonate (Moravek Biochemicals, Brea, USA) and distributed in 10 clear bottles (20 ml each). Subsequently they were incubated for 12 h at -1.3°C under different scalar irradiances (0-420 µmol photons m-2 s**-1) measured with a spherical sensor (Spherical Micro Quantum Sensor US-SQS/L, Heinz Walz, Effeltrich, Germany). At the end of the incubation, samples were filtered onto 0.2 µm nitrocellulose filters and the particulate radioactive carbon uptake was determined by liquid scintillation counting using Filter count scintillation cocktail (Perkin Elmer, Waltham, USA). The carbon uptake values in the dark were subtracted from the carbon uptake values measured in the light incubations. Dissolved inorganic carbon (DIC) was measured for each sample using the flow injection system (Hall and Aller, 1992). The DIC concentration was taken into account to calculate the amount of labeled bicarbonate incorporated into the cell. Carbon fixation rates were normalized volumetrically and by chlorophyll a. Photosynthesis-irradiance curves (PI curves) were fitted using MATLAB® according to the equation proposed by Platt et al. (1980) including a photoinhibition parameter (beta) and providing the main photosynthetic parameters: maximum Chla normalized carbon fixation rate if there were no photoinhibition (Pb) and the initial slope of the saturation curve (alpha). The derived parameters: light intensity at which photosynthesis is maximal (Im), the carbon fixation rate at that maximal irradiance (Pbm) and the adaptation parameter or photoacclimation index (Ik) were calculated according to Platt et al. (1982).

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Creator Fernández-Méndez, Mar ORCID logo; Peeken, Ilka ORCID logo; Boetius, Antje ORCID logo
Publisher PANGAEA
Publication Year 2014
Funding Reference Seventh Framework Programme Crossref Funder ID 294757 Assessment of bacterial life and matter cycling in deep-sea surface sediments
Rights Creative Commons Attribution 3.0 Unported;
OpenAccess true
Resource Type Dataset
Format text/tab-separated-values
Size 1306 data points
Discipline Earth System Research
Spatial Coverage (17.454W, 77.397S, 133.342E, 88.828N); Arctic Ocean; Laptev Sea
Temporal Coverage Begin 2012-08-06T07:04:00Z
Temporal Coverage End 2012-09-29T15:10:00Z