Buesseler notes:

            Where greater than 53 micron data is missing,
  	    1 to 53 micron is actually greater than 1 micron
            size fraction.

            The "Slurper" is an in-situ pump capable of sampling
            discrete depths or integrating over a depth range.

            On TTN043 and TTN045, surface samples were collected 
            using the ship's seawater line.  On TTN049, surface
            samples were collected using both the ship's line and
            the Slurper.  On TTN050, all samples were collected with
            the Slurper, including surface samples.