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All samples collected to quantify live organisms or water quality are taken by inline
sampling of ballast water during the initial filling or during discharge of water from the ship’s
tanks by sample ports placed in appropriate filling or discharge pipes. All sample ports include a
valve and sample tube with a 90
o
bend towards the direction of flow, placed in the center of the
piping system (based on the design developed and validated by the US Naval Research
Laboratory, Key West Florida).
A total of 10 identical conical bottom mesocosms (shown below) have been installed on
the
Cape Washington
to allow for precise and controlled sampling during each test trial. Five
replicate mesocosms are used to sample initial challenge conditions at the start of each trial,
prior to the split in water to control and test tanks. The second five mesocosms are used to
sample after water has passed through the treatment during the initial filling of the test tank. At
the end of each trial (after five-days), five mesocosms are used for sampling water from the
control tank and the second five mesocosms for water from the test tank. At each sampling time
(initial and after holding time), the designated five mesocosms were filled to approximately 1.05
m
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in sequence, drawing continuously over approximately 80% of the total 90 minutes required
to fill or drain the ship’s ballast tanks. Immediately after filling of each mesocosm (< 5
minutes), physical parameters of the water are measured (see below), and then the precise
sample volumes described below are collected for each biological and water quality categories
by gravity draining through a bottom valve and tubing. Each mesocosm has been calibrated and
marked with known volumes to assure accurate sample collection. Each mesocosm is also
rinsed thoroughly with potable water for a minimum of three times after each use and kept clean
and dry between uses.