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SeaHARRE-3 : the third SeaWiFS HPLC Analysis Round Robin Exercise

SeaHARRE-3 : the third SeaWiFS HPLC Analysis Round Robin Exercise. Scientific Objectives. History 2 previous SeaHARRE exercises, coordinated by S. Hooker (NASA) and LOV: 1999: PROSOPE : mainly mesotrophic; 4 labs (Ref: Hooker et al, 2000; Claustre et al. 2003)

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SeaHARRE-3 : the third SeaWiFS HPLC Analysis Round Robin Exercise

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  1. SeaHARRE-3 : the third SeaWiFS HPLC Analysis Round Robin Exercise Scientific Objectives History 2 previous SeaHARRE exercises, coordinated by S. Hooker (NASA) and LOV: 1999: PROSOPE: mainly mesotrophic; 4 labs (Ref: Hooker et al, 2000; Claustre et al. 2003) 2002: BENCAL: mainly eutrophic waters; 8 labs. Agreement between labs: 7% for TChla; 21% for other pigments. “Well within the primary 35% accuracy objective for remote sensing validation purposes” SeaHARRE-3 • Application to extremely low Chlorophyll a concentrations • All participating labs are working on improvement of different methodologies and instrumentation for lower detection limits, better resolution (>1) and higher precision (99%). • 8 Participating labs • Organisers: S. Hooker, H. Claustre, L. Van Heukelem, J. Ras

  2. Methods and measurements to be made Sampling: • Water will be collected at 24 sites and at various depths and trophic conditions. • For oligotrophic and mesotrophic waters: in situ pump with 293 mm diameter GF/F filter. • CSIRO (L. Clementson) is building a punch for cutting out more than 60 replicates from a single filter. • For eutrophic waters (and for regular pigment sampling): 24 post filtration system; positive pressure (to be built). • On board filtration will require thorough mixing of water to maintain homogeneity. Measurements: • HPLC measurements by 8 different labs. Each lab receives 24 batches of 3 replicates. • Other tests will be carried out on remaining replicates

  3. Sampling Water volumes: • For in situ sampling (in collaboration with the IAEA team): • Usually 1h pumping of about 800 L is equivalent to about 6 L on a 25 mm GF/F filter. • For on board filtering (also concerns regular pigment sampling) • Water volume is variable according to Chlorophyll a concentration. First, this will be determined by Turner Fluorimetry (P. Raimbault) providing an estimate of the volume of water to filter for pigments. • A whole CTD cast will be required to collect 24 replicates (long stations only). • Limits of detection of the HPLC method are being improved: maximum volume may vary between 2.8 and 5.6 L per sample in oligotrophic conditions. Minimum volume can reach 0.25 L in eutrophic waters. Technical requirements: • Enough time for in situ pumping (about 1 hour) • Safe transport of samples to their various destinations (Europe, North America, South Africa, Australia). Any ideas?

  4. Regular sampling for phytoplankton pigments • 2 CTD casts per day (up to 12 depths): 1 in the morning, 1 at midday. (In all cases the midday cast must be maintained). • A surface sample will be taken every time in situ optical measurements will be made (Pump? Bucket?). • Necessary water volume per sample: as mentioned before, this depends on result of the Turner fluorimetry measurement. ☼

  5. Participating labs • Laboratoire d’Océanographie de Villefranche – H. Claustre, J. Ras • Horn Point Laboratory (USA)– L. Van Heukelem • Marine Coastal Management (South Africa) – Ray Barlow • CHORS (USA) – Chuck Trees • University of Hawaii (USA) - R. Bidigare • JRC (Italy) – J.F. Berthon • CSIRO (Australia) – L. Clementson • ?

  6. GF/F filter after filtration Variation coefficient of replicates: 4 to 7.6% In situ pump

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