This record contains data collected on the RV Lady Basten (AIMS cruise code LB2108/99) in the Exmouth Gulf from 25 February to 2 March 1999. The data were collected to determine the bio-optical characteristics of this region. The data can be used for Ocean Colour sensor validation. Parameters measured are the concentration of chlorophyll and carotenoid pigments and the absorption coefficient for dissolved (CDOM) particulate (a/p) and detrital or non-algal (a/d) components of the water column.
Water samples were taken on-board the RV Lady Basten. Samples were filtered onboard. Samples were analysed and QC procedures were carried out in the Ocean Colour Laboratory. Pigment analysis: 4-6 litres of sample water was filtered through a 47 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 high performance liquid chromatograph, comprising a 600 controller, 717 plus refrigerated autosampler and a 996 photo-diode array detector. Pigments were separated using a stainless steel 25 cm x 4.6 mm I.D. column packed with ODS2 of 5 µm particle size (SGE) with gradient elution as described in Wright et al., . The separated pigments were detected at 436 nm and identified against standard spectra using Waters Millenium software. Concentrations of chlorophyll a, chlorophyll b, b,b-carotene and b,e-carotene in sample chromatograms were determined from standards (Sigma) and all other pigment concentrations were determined from standards of purified pigments isolated from algal cultures. Spectral absorption: 4 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.
William Skirving (AIMS)