Fig. 2. Location of sample collector columns and method of compositing samples. Water from the bottles at the same height (1.22 or 0.61 m) and distance (i.e., those indicated on the same circle in the diagram) from the riser were composited. For example, water from all T bottles on the 2.44-m circle were composited into one bottle and water from all B bottles on that same circle were composited into another bottle.