Sediment pigment analysis at Casey Station, 2014-2015

General description: The associated file contains sediment pigment data from the antFOCE project 4127. Units: all pigment data in ug/g, 0 = below detection limit of HPLC. Sample collection details: At the start and end of the antFOCE experiment, four sediment core samples were taken from inside and outside each chamber or open plot by divers. The top 1 cm of the cores was then removed and placed in the dark, first at -20ºC for 2 hours, then at -80ºC until analysis at the Australian Antarctic division. Pigment analysis Frozen samples were transported under liquid N2 to a freeze drier (Dynavac, model FD-5), in pre-chilled flasks with a small amount of liquid N2 added. Custom made plumbing fitted to the freeze drier enabled samples to be purged with N2 to prevent photo-oxidation up until solvent extraction. Prior to pigment extraction five 2 g stainless steel ball bearings were added to homogenise the freeze dried sediment. The samples were bead beaten for 1 minute (Biospec products). Subsamples (~0.05 g) were immediately transferred to cryotubes with 700 µl of dimethylformamide (DMF) for two hours. Samples were kept at -80ºC and under a safe light (IFORD 902) at all times. All pigment concentrations are standardised to sediment weight. Pigments were extracted with dimethylformamide (DMF 700 µl) over a two hour period at -20ºC. Zirconia beads, and 100 µl of Apo 8 and an internal standard were added to each sub-sample. After a two hour extraction, sub-samples were bead beaten for 20 seconds and then placed in a centrifuge with filter cartridge inserts for 14 minutes at 2500 rpm at -9ºC to separate the solvent from the sediment. The supernatant was transferred into to a vial and placed in a precooled rpHPLC autosampler. The rpHPLC system used is described in Hodgson et al. (1997). Pigment detection was at 435, 470 and 665 nm for all chlorophylls and carotenoids, with spectra from 300–700 nm being collected every 0.2 seconds. Pigment identification was carried out using a combination of rpHPLC and normal phase HPLC retention times, light absorbance spectra and reference standards (see Hodgson et al., 1997). These techniques assisted in the accurate identification of pigments and their derivatives to a molecular level and enabled several pigment derivatives to be analysed. The HPLC was previously calibrated with authentic standards and protocols outlined in SCOR (1988). Data set headers: (A)Treatment: Example code 4127_SOP7_6-1-15_PlotB_R1, = prodject code_Standard Operating Procedure(SOP) used to collect samples(see antFOCE parent file)_ Date_Chamber/plot(A,B,C,D)_replicate core within Chamber/plot(1,2,3) (B) BB carot= BB caroten, type of pigment detected by HPLC. See Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more details. (C) Chl c1 = Chlorophyll derivatives see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information. (D) Chl c2 = Chlorophyll derivatives see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information. (E) Chl c3 = Chlorophyll derivative see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information. (F) Chla = Chlorophyll a see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information. (G) Ddx =Diadinoxanthin see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information (H) dtx = Diatoxanthin pigment. see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information (I) epi = Chlorophyll epimer pigment. see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information. (j) Fuc = Fucoxanthin pigment. see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information. (k) Gyro2 = Gyroxanthin pigment. see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information. (L) Pras = Prasanthin pigment. see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information. (m) Zea = Zeaxanthin pigment. see Wright, S.W., Jeffrey, S.W. and Mantoura, R.F.C. eds., 2005. Phytoplankton pigments in oceanography: guidelines to modern methods. Unesco Pub for more information. (n) Date = Samples taken at the start of antFOCE experiment or at the end (o) chamber = The antFOCE chamber (A,B,C,D) (p) Treatment = The associated pH level in chambers (Acidified ~7.8, Control ~8.2) (Q) Position = Samples were taken within chambers and outside chambers (outside, inside) (r) rep= Subsamples were taken within each chamber/position (R1=replicate one, R1-R4) Spatial coordinates: 66.311500 S, 110.514216 E Dates: between 1/12/2014 and 1/3/2015 Timezone:UTC+11