WET Labs

CDOM Detection and Measurement of Crude Oil

WET Labs' sensors have been field-proven worldwide, most recently in the Gulf of Mexico, where monitoring of crude oil plumes has greatly increased the demand for these highly robust instruments.

The presence of both scattering and fluorescence is an excellent indicator of the existence of an oil emulsion. These sensors are effective crude oil fluorometers because crude oil has extremely broad absorption and emission spectra and the emission wavelength of the CDOM fluorometers is centered at the primary crude emission peak. Read more

Best Practices
Because the CDOM fluorometer will respond to a wide range of fluorophores other than crude oil, ancillary measurements are useful to decrease false positive results.

For crude oil spills in offshore "blue water" conditions such as the outer shelf and deep water of the Gulf of Mexico, CDOM fluorescent response should be quite low and high positive response in CDOM raw counts on the order of tens to hundreds of counts would indicate the presence of crude oil. Read more

ECO CDOM Fluorometer in Action: Open Publications

Current Joint Analysis Group (JAG) Reports
• JAG Report 1
• JAG Report 2
• Instrument drift checks

Maps and Data can be found at NOAA Science Missions & Data: Deepwater Horizon, as well as specific reports—
• NOAA evaluation of CDOM fluorometer performance
• Monitoring subsurface oil using CDOM fluorometry

GeoPlatform provides near-real-time data for a number of variables.

Use the Interactive Map to see CTD and CDOM sampling stations— Subsurface Monitoring > Water Column Results > Analytical Chemistry > CTD Sampling > All vessels CTD/DO/ Fluorescence

Research by Texas A&M presented at the 2005 International Oil Spill Conference presents the reliable data of the ECO CDOM fluorometer. Read more

University of Georgia Gulf blog... read
• May 2010 post of CDOM work--"Trust your senses"

Sensors for Profiling Applications

.	CDOM (Model FLCDRTD)	Triplet (Model FLbbCD)	Chloropyll-Turbidity (Model FLNTURTD)
*Depth*	6000 m	2000 m	6000 m
*Range*	0–500 ppb	Chl: 0–50 µg/l scattering: 0–5 m^-1 CDOM:0–375 ppb	Chl: 0 to 50 µg/l Turbidity: 0–25 NTU
*Sensitivity*	0.09 ppb	Chl: 0.03 µg/l scattering: 0.003 m^-1CDOM: 0.28 ppb	Chl: 0.025 µg/l Turbidity: 0.01 ntu
*EX/EM*	370/460 nm	Chl: 470/695 nm scattering: 700 nm CDOM: 370/460 nm	Chl: 470/695 nm Turbidity: 700 nm
.	more	more	more

Sensors for Long-term Moored Applications

..	CDOM (Model FLCDS/B)	WQM	Chloropyll-Turbidity (Model FLNTUS/B)
*Depth*	300 m	200 m	300 m
*Parameter*	CDOM	CTD, DO, NTU, Chl-a	chlorophyll , turbidity
*Options*	Internal batteries Bio-wiper ™	50 AH alkaline battery pack	Internal batteries Bio-wiper ™
.	more	more	more

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