March 13, 2001 to June 2, 2001
Monterey to Hawaii and back
May 23, 2001: Leg 5; Day 2
Ken J. writes: Today we learned there is not a secret 5th engine on the Western Flyer. There is a secret, extra fuel tank. The Western Flyer is making 11 knots through almost flat calm seas, instead of the planned speed of 8 knots for maximum fuel economy. There is hardly a ripple on the ocean, just a long swell running. So we are "making extra speed in case the weather turns." This must prove that we live a more virtuous life than the geologists, who fought high winds, high seas and high currents on their three legs of the expedition.
Yesterday evening we occupied our first station at the Hawaii Ocean Time (HOT) series site. It was the first cast with a brand new rosette/CTD that had not been wet before. We were still pulling tags and warning labels off as it went overboard. This system is designed to give uncontaminated samples for iron from deep water. Everything worked flawlessly and we left station 30 minutes ahead of schedule after a cast to 1500 meters. We’re just running the first samples for dissolved iron now and things look good. A 10-year long record of ocean biogeochemical processes has been accumulated at the HOT site – check their web site for a nice, on line data system with all of their measurements. We hope to contribute to the understanding of this system with our work on Surface Ocean/Lower Atmosphere Studies in this region.
Our next hydrocast comes this evening at the Dive 8 station of the outbound leg. Between stations, we’re pulling our trace metal pumping system behind the ship. This system pulls uncontaminated seawater up to the ship from a few meters depth with a TeflonÔ pump and then distributes it through the wet lab. If anything comes unplugged in this system, then "distribution of water through the wet lab" is the perfect description. We analyze trace metals by Flow Injection Analysis with chemiluminescence detection for iron and with fluorescence detection for aluminum. Iron reacts with the organic chemical luminol, in the analytical system, creating a photon of light. Our instruments patiently collect the very few photons generated at the extremely low iron concentrations (~100 picomoles/liter – a few parts per million of a part per million) found in this remote area and then report the concentration of iron every 15 minutes. We spend our time keeping two instruments happy measuring iron and one measuring aluminum, which is far more work than it sounds. In between we collect samples to analyze for particulate metals at Moss Landing Marine Laboratories and samples of phytoplankton to assess the impacts of dust iron on the ecosystem. To learn more about Flow Injection Analysis visit the MBARI Chemical Sensor home page.
Well, I hear the aluminum system is not very happy right now, and I’m off to investigate.