Ref. No. [UMCES] CBL 2013-020
ACT VS12-03
following 30 minute exposure. Instrument response, reported as the average of 5 minutes of
readings encompassing reference sample times, was used to characterize instrument response at
each challenge level. Instrument response factors are calculated by regression of mean
instrument output against challenge compound concentrations. Precision tests were conducted
by monitoring the variance of instrument response over the 5 minute periods. Originally
proposed turbidity and CDOM interference tests, and temperature response factors, were not
conducted.
Table 1.
Challenge compounds for laboratory evaluations of hydrocarbon sensors.
Compound
Ex
Em
Carrier
Stock (ppm)
Carbazole
270
342, 358
methanol
5000
1,5-Naphthalene
Disulfonic Acid
270
380
0.05 M H
2
SO
4
5000
Quinine Sulfate
350
450
0.05 M H
2
SO
4
5000
Basic Blue 3
250, 320
430
water
5000
Diesel Fuel
SPEX CRM
250-300
350-500
methanol
5000
Performance against crude oil challenge compounds and dispersants in a Wave Tank Test
A test application of instrument response against crude oil compounds, with and without
addition of dispersant, was performed in a simulated water column using the DFO/US EPA
Wave Tank Facility located at the Bedford Institute of Oceanography, Dartmouth, Nova Scotia,
Canada (BIO-COOGER). Reference samples were collected from the tank to allow real-time
characterization of the sample water with three-dimensional Excitation/Emission spectroscopy
(EEMS).
Instrument performance was examined against two types of crude oil, Arabian Light
(weathered 7%) and Alaskan North Slope, run under two conditions including the pure oil
compounds and with compounds at oil to dispersant ratio of 25:1. The test materials were created
experimentally at BIO-COOGER using the two source oils and Corexit 9500 dispersant.
Experiments were performed in a step-up addition batch mode with breaking waves to physically
disperse the oil throughout the tank. Oil additions were cumulative to the same batch of water
and were made at six timepoints at approximately one hour intervals. The amount of oil added
ranged between 0 to 360 grams and produced oil concentrations of 0, 0.3, 0.6, 1.5, 3.0, 6.0, and
12.0 ppm, respectively, at each consecutive step. Reference sampling occurred 50 minutes after
each new oil addition. Continuous instrument records were sub-sampled to the last 10 minutes
of equilibrated conditions of the exposure period and corresponding reference sampling times.
A Seabird SBE26+ CTD, SeaPoint chlorophyll fluorometer and LISST particle analyzer
were deployed to provide ancillary time-series data on water quality and to confirm degree of
physical dispersion of added oil. Reference samples were collected from three sampling inlet
ports distributed across the width of the tank and located adjacent to the sensor window. An
aggregate sample was produced for the reference sample analyses, except for hydrocarbon
subsamples which were taken and analyzed independently. Hydrocarbon analysis was conducted
on-site by certified BIO-COOGER facility personnel using either gas chromatography with a
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