Spectrophotometric measurements of absorption coefficients by phytoplankton during POLARSTERN cruise PS113 along an Atlantic Transect


Water samples were taken during the transatlantic (10 May to 9 June 2018) expedition PS113 with RV Polarstern. Water samples were collected from CTD Niskin bottles at six different depths from the upper 100 to 180 m and additionally from the ship's seawater supply pumped through teflon tubing from about 11m depth during underway further described for HPLC based phytoplankton pigment data in Bracher et al. (2020). All collected samples were filtered through 25 cm Whatman GF/F filters, respectively, under low-vacuum pressure (below 200 mbar). Blank filters were collected by soaking them in 0.2um filtered seawater. Measurements for particulate and non-algal (NAP) absorption were performed directly after filtration the quantitative filtration techniques-intergrative cavity measurement device and procedure from Röttgers et al. (2016) as described in Liu et al. (2018). Phytoplankton absorption (aph) was derived by subtracting the NAP from the particulate absorption.

Further specifications on the measurements:a) Instrument: light source: UV-VIS lamp (CF-1000- HC lamp, Illumination Technology, USA); absorption meter: Quantitative Filter Technique - Integrating Cavity Absorption Meter (QFT-ICAM) (Röttgers et al., 2016) with 80 mm- diameter integrating sphere; detector: photodiode array spectrometer (AVASPEC-ULS2048-RS-USB2, Avantes, the Netherlands).b) wavelength range of scan and resolution: 313.5-875.7 nm, 0.3 nm.c) slit band width: 2 nm.d) sample filters were bleached with 10% sodium hypochlorite (NaClO) solution for the OD measurement of NAP.e) samples were measured for four times and bleached samples were measured twice.f) dark current and blank filters were measured and subtracted.Further specifications about data analysis:a) interpolated wavelength range and resolution: 320-844 nm, 2nm.b) wavelength range for fluorescence correction: 670:800 nm.c) diameter of sample patch on GF/F filter: 2.133 cm.d) pathlength amplification factor (beta correction factor): 4.06 (Röttgers et al., 2016).e) no scattering correction for total particle absorption is applied; NAP absorption was adjusted with an offset in the range of 710-750 nm so that the median value of NAP absorption equals the median value of in total particle absorption in this spectral range. This adjustment is based on the assumption that phytoplankton pigments do not absorb in near-infrared (Neeley et al., 2018). This adjustment was not applied to NAP OD data.

DOI https://doi.pangaea.de/10.1594/PANGAEA.938178
Related Identifier https://doi.pangaea.de/10.1594/PANGAEA.938185
Related Identifier https://doi.org/10.3389/fmars.2020.00235
Related Identifier https://doi.org/10.1364/OE.26.00A678
Related Identifier https://doi.org/10.25607/OBP-119
Related Identifier https://doi.org/10.1364/OE.24.0000A1
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.938178
Creator Bracher, Astrid; Liu, Yangyang; Xi, Hongyan; Wiegmann, Sonja
Publisher PANGAEA - Data Publisher for Earth & Environmental Science
Publication Year 2021
Funding Reference German Science Foundation, 268020496
Rights Data access is restricted (moratorium, sensitive data, license constraints)
OpenAccess false
Language English
Resource Type Dataset
Format text/tab-separated-values
Size 78888 data points
Discipline Earth System Research
Spatial Coverage (-62.021W, -48.639S, -0.137E, 50.278N); South Atlantic Ocean; North Atlantic Ocean; Canarias Sea
Temporal Coverage Begin 2018-05-10T11:01:00Z
Temporal Coverage End 2018-06-09T10:58:00Z