The Japan Agency for Marine-Earth Sciences and Technology (JAMSTEC) sponsored this research cruise - a circumnavigation of the Southern hemisphere using the World Ocean Circulation Experiment (WOCE) Hydrographic Program (WHP) lines in the southern hemisphere to celebrate the 30th anniversary of its establishment. The research cruise was named "BEAGLE 2003" (Blue EArth GLobal Expedition 2003) and carried out on the RV MIRAI. This is a subset of the Beagle 2003 data set and contains the HPLC pigment and particulate absorption coefficient data collected on leg 4, between Santos, Brazil and Cape Town, South Africa from the 7 Nov to 1 Dec 2003. The data can be used for Ocean Colour sensor validation. Parameters measured on the leg are the concentration of chlorophyll and carotenoid pigments and the absorption coefficent for particulate (a/p) components of the water column. Samples were collected at 33 stations. The data was used primarily to validate ocean colour sensors MERIS, MODIS and SeaWIFs and the SST sensor AATSR.
Progress Code: completed
Maintenance and Update Frequency: notPlanned
Statement: Water samples were taken on-board the RV Mirai and stored under cool and dark conditions until filtering took place on board the vessel. Samples were analysed and QC procedures were carried out in the Ocean Colour Laboratory, CSIRO, Hobart, Tasmania, Australia. Pigment analysis; between 1-2.5 litres of sample water was filtered through a 25 mm glass fibre filter (Whatman GF/F) and then stored in liquid nitrogen until analysis. To extract the pigments, the filters were cut into small pieces and covered with 100% acetone (3 mls) in a 10 ml centrifuge tube.
The samples were vortexed for about 30 seconds and then sonicated for 15 minutes in the dark. The samples were then kept in the dark at 4 °C for approximately 15 hours. After this time 200 µL water was added to the acetone such that the extract mixture was 90:10 acetone:water (vol:vol) and sonicated once more for 15 minutes. The extracts were centrifuged to remove the filter paper and then filtered through a 0.2 µm membrane filter (Whatman, anatope) prior to analysis by HPLC
using a Waters Alliance high performance liquid chromatography system, comprising a 2695XE separations module with column heater and
refrigerated autosampler and a 2996 photo-diode array detector. Immediately prior to injection the sample extract was mixed with a buffer solution (90:10 28 mM tetrabutyl ammonium acetate, pH 6.5 : methanol) within the sample loop. Pigments were separated using a Zorbax Eclipse XDB-C8 stainless steel 150 mm x 4.6 mm ID column with 3.5 µm particle size (Agilent Technologies) with gradient elution as described in Van Heukelem and Thomas (2001). The separated pigments were detected at 436 nm and identified against standard spectra using Waters Empower software. Concentrations of chlorophyll a, chlorophyll b, b,b-carotene and b,e-carotene in sample chromatograms were determined from standards (Sigma, USA or DHI, Denmark). Spectral absorption; between 1-2 litres of sample water was filtered through a 25 mm glass fibre filter (Whatman GF/F) and the filter then stored flat in liquid nitrogen until analysis. Optical density spectra for total particulate matter were obtained using a GBC 916 UV/VIS dual beam spectrophotometer equipped with an integrating sphere.
Ian Barton, The Japan Agency for Marine-Earth Sciences and Technology (JAMSTEC) (sponsor of research cruise)