Ref. No. [UMCES]CBL 2013-021
ACT VS12-05
components. The ECO FLCDRTD fluorometer is used to monitor CDOM concentration by
directly measuring the amount of CDOM fluorescent light emission from a given sample volume
of water. Three 370 nm UV LEDs modulated at 1.4 KHz provide the excitation source. An
interference filter is used to reject the small amount of visible light emitted by the LED. The UV
light from the source enters the water volume at an angle of 60 degrees with respect to the end
face of the unit. Fluoresced light is received by a detector positioned where the acceptance angle
forms a 140 degree intersection with the source beam. A 460 nm peak, 120 nm FWHM
bandpass filter and blue light long-pass filter set discriminates against scattered and ambient
light. The red fluorescence emitted is synchronously detected by a silicon photo diode. The
manufacturer’s published performance specifications for the FLCDRTD fluorometer include:
Sensitivity (per count) +/- 0.09 ppb QSDE, Range 0 to 500 ppb QSDE, Linearity 99% R
2
, and
operating depth of 0 – 600 meters, 0-200 m (with bio-wiper) and 0 -6000 m (deep rated,
Titanium housing.) More information can be found at
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 the 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
report,
Protocols for the ACT Verification of In Situ Hydrocarbon Sensors
(ACT PV11-01) and
can be downloaded from the ACT website
.
Analysis of Reference Samples
Hydrocarbon concentrations
Diesel range hydrocarbons (C10 to C36) and volatile organic hydrocarbons were
analyzed by using GC-FID by the contract laboratory, Test America (West Sacramento Lab),
