Ref. No. [UMCES]CBL 2013-014
ACT VS12-01
analyte detection is tuned by inclusion of appropriate optical filters on the excitation pathway
and emission window oriented at 90
°
to the excitation beam. The Aquatracka UV-CDOM
incorporates a 239 nm excitation filter (20 nm FWHM) and a 440 nm (80 nm FWHM) emission
filter set, while the Aquatracka UV-HC version incorporates the same 239 nm (20 nm FWHM)
excitation filter paired with a 360 nm (54 nm FWHM) emission filter. The hydrocarbon version
also utilizes additional filtration specifically to block excitation light at the emission detection
wavelengths to provide additional turbidity rejection. Based on the bandwidth of the specified
filters some overlap in detection capability is to be expected.
Designed to be deployed from undulating vehicles, moored or profiling systems, this
robust, compact, lightweight instrument has built in test (BITE) circuitry that ensures high
stability. The instrument is easy to use and gives accurate and repeatable measurements.
The UV Aquatracka uses a titanium pressure housing, rated to 6000m and has an optional
ambient light-baffling cowl for use in surface waters. It utilizes a pulsed xenon light source, a
miniature PMT as the detector and incorporates a 20-bit ADC under the control of a micro
controller. Data output is factory set as logarithmic analogue (1V per decade) which gives very
high resolution at low concentrations. For deck and laboratory applications a flow through
cowling is available. The standard measuring ranges for the UV-HC and UV-CDOM are 0.001 to
10 µg/l (Carbazole and Perylene, respectively) with a resolution of 0.001 µg/l and a sampling
rate of 4Hz (optional 10Hz).
SUMMARY of VERIFICATION PROTOCOLS
The protocols used for this performance verification were developed in conference with
ACT personnel, the participating instrument manufacturers and a technical advisory committee.
The protocols were refined through direct discussions between all parties during a Hydrocarbon
Sensor Performance Verification Protocol Workshop held on 2-4 February, 2011 in Moss
Landing, CA. All ACT personnel involved in this Verification were trained on use of
instruments by manufacturer representatives and on standardized water sampling, storage,
analysis and shipping methods during a training workshop held on 18-20 May 2011 in Moss
Landing, CA. The manufacturer representative and the ACT Chief Scientist verified that all staff
were trained in both instrument and sample collection protocols.
This performance verification report presents instrument output voltage, relative
florescence units or derived hydrocarbon values reported over time, position, or depth as directly
downloaded from the test instruments or captured through independent dataloggers. The report
includes means, standard deviations, and number of replicates of laboratory determined Diesel
Range Organics, Volatile Hydrocarbons, EEMS, Absorbance, CDOM and Chlorophyll values for
corresponding reference samples at the same time, position, or depth of the instrument
measurements. The report also includes turbidity values for each sample measured on site using
a Hach Turbidimeter which was used for all laboratory and field tests. Instruments were tested
under four different applications, including: (1) laboratory tests with known additions of variance
hydrocarbons; (2) a wave tank test with known additions of crude oil with and without
dispersant; (3) a moored deployment in Baltimore Harbor; and (4) vertical profiling deployments
in the Gulf of Mexico at a site with known leaking bunker oil. A summary of the testing
protocols is provided below. A complete description of the testing protocols is available in the
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