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Ref. No. [UMCES] CBL 2015-010
ACT VS15-03
conditions. Each test was scheduled to last 1 week, except when delays were needed to
accommodate work schedules. For each new T-S test condition, the test tank was flushed and
filled with new source water while keeping all test instruments submerged and recording
continuously. Each new batch of source water was filtered through a 1 µm cartridge prior to use
in the tests.
Laboratory Test Reference Sampling -
During the stable temperature and salinity period,
reference samples were collected and analyzed at 4 timepoints each day. In addition, on one day
during the stable cycle, a burst sampling of five independent measurements were collected 5
minutes apart at one of the timepoints to evaluate the repeatability and uncertainty of the
reference measurement with respect to the variability observed within the test tank. Reference
samples were drawn directly into the spectrophotometer cell from a supply tube within the test
tank. After the cell was blanked and prior to the dye addition and spectrophotometric readings,
the temperature of the cell was measured and adjusted to within 0.1 degree or less of the tank
temperature. 10 readings of the reacted dye were recorded over 1-2 minutes for each sampling
timepoint, and a mean and standard deviation of each reference measurement was calculated.
The final temperature of the sample in the cell was recorded immediately after reading to define
any deviation from the specified reading temperature. The temperature of the sample stream was
monitored continuously and the salinity of the sample stream was measured on duplicate sub-
samples with a Guideline Portasal. Once during the stable phase of a given T-S test condition a
more detailed burst sampling was conducted, where 6-8 samples were collected over the course
of an hour to assess the fine-scale variability (temporal and spatial) of test tank conditions.
During the pH cycling phase of the test, 2 reference sampling timepoints were completed during
each endpoint (approximately an hour after acid/base addition) of the increase or decrease. Each
phase (increase or decrease) occurred over roughly 2 hour intervals.
Lastly, duplicate water samples were collected at the beginning and end of the stable test
condition period (day 1 and day 5) to characterize all of the CO
2
parameters. Water samples
were taken for pCO
2
, Dissolved Inorganic Carbon and Total Alkalinity measurements and
preserved and stored in accordance with standard oceanic protocols (Dickson et al., 2007). These
water samples were shipped to Oregon State University (Burke Hales, OSU) and Scripps
Institute of Oceanography (Andrew Dickson, SIO) for analysis. In addition, preserved water
samples were shipped to SIO (Andrew Dickson) and University of South Florida (Robert Byrne,
USF) for measurements of pH, thereby providing further indication of the uncertainty of ACT’s
reference sample measurements. However, because these samples were not handled identically
to the reference samples analyzed real-time and directly from the test tank, they will not be used
in any direct assessment against the test instruments without review from the TAC and consent
from the manufacturer. Nutrients were also measured on these samples in Atkinson's lab.
Moored Field Tests
Moored field tests were conducted at four ACT Partner Institution sites covering
freshwater, estuarine, and open-ocean conditions. The test sites include Moss Landing Marine
Laboratories (MLML), CA; Hawaii Institute of Marine Biology (HIMB), HI; Chesapeake
Biological Laboratory (CBL), MD; and Lake Michigan, MI. The field tests occurred in
sequence, starting with Moss Landing on August 22, 2013. The duration of the moored
deployment tests were 4 weeks, except at the Hawaii test site where instruments were deployed
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