Post on 15-Jan-2016
In-situ fluorometry for oil-spillsChris FullerJim Bonner
Department of Civil EngineeringTexas A&M University
ABSTRACT
The current SMART protocol used by the U.S. Coast Guard relies on traditional ex-situ fluorometers that require physical transport of the sample from the water column to the instruments. While sample transport methods are available (e.g. pumps and discrete sampling), they introduce time lags in the data acquisition process. These lags can be a source of error when the data is post analyzed and is not conducive to real-time monitoring efforts, creating significant logistical problems and dispersion (smearing) of the sample stream. Another limitation of the currently-used equipment is that it requires much attention to manually record GPS data which is later used to determine the spatial distribution of an oil plume. Recent developments of in-situ fluorometric instrumentation promise to simplify problems associated with deployment of ex-situ instrumentation (e.g. insuring that pumps are primed) in boat-based field applications. This study first compares the performance of two in-situ fluorometers in a simulated oil and dispersant application at the Shoreline Environmental Research Facility at Texas A&M University in Corpus Christi, Texas. The fluorometers were the WETStar and the ECP-FL3 (both by WETLabs, Inc.). To address issues related to data collection from a GPS and a fluorometer, a system was developed that simultaneously merges data from both instruments into a single file and presents the data real-time as a color-coded ship track. The applicability of this system was tested and evaluated during a spill response exercise conducted by the Texas General Land Office and the U.S. Coast Guard in Galveston Bay, Texas, U.S.A.
In-situ Fluorometry
Recent advances in technology have led to development of in-situ fluorometry
Benefits include
Ease of deployment
Alleviates sampling lag
Alleviates problems associated with sample transport
Contaminated lines
Loss of prime on pumps
Etc.
Proven Tehcnology
Laboratory studies
Show that in-situ fluorometers can easily detect oil in water
Chemically dispersed oil
Soluble oil
Shoreline Environmental Research Facility
Meso-scale demonstration of in-situ fluoromtry in dispersant application
Natural seawater (i.e. ambient particles)
Used to detect chemically dispersed oil
Instruments used
ECO-WETstar
ECO-FL3
Results compared to TPH determined by GC/M
Ability to evaluate under real world applications
Waves
Turbidity
ECO-WETStar Meso-Scale Testing Results
ECO-WETStar uses flow cell (i.e. unit must be towed to get sample)
Peaks indicate that unit was towed through center of plume
ECO-FL3 Meso-scale results
Values represent averages of from short sampling interval at tank locations identified
CDO concentrations were heterogeneous at t=30 min.
At t=60 min, CDO concentration was more evenly distributed throughout tank
No flow cell gives ability to make measurements at discreet location w/out use of pumps
ECO-FL3 versus GC-MS Analyses
Results show good correlation between fluorescence and GC-MS (TPH) values
Indicates that units useful tools for measuring chemically dispersed oil in near shore marine environments
SERF Demonstration
Motorized bridge with dispersant nozzles, ECO-WETstar (BUBA configuration)
Lead sounding weight used to orient ECO-WETstar in direction of tow.
InstrumentationIn-situ
Wetlabs
ECO-FL3
Chlorophyll A(470nm/695nm)
Fluoroscein (470nm/530nm)
CDOM (370nm/460nm)
ECO-WETstar
CDOM (370nm/460nm)
Ex-situ
Turner 10-AU
Long-wavelength oil kit (300-400nm/500±100nm)
Meso-scale Testing
Fluorometer results were compared to TPH values obtained from discreet samples
ECO-WETStar (BUBA Buster Configuration)
BUBA Deployment During SOO ExerciseBUBA Deployment During SOO Exercise
BUBA Deployment During DEPOL Experiment (Brest, France)
SOO Exercise
Participants Texas General Land Office
U.S. Coast Guard
Clean Channels Association
Texas A&M University
Location Galveston Bay, Texas
Simulated Oil Spill and Dispersant Application
Spill simulated with fluoroscein
Applied from boat
Dispersant simulated with rhodamine
Applied from aircraftInstrumentation WetLabs-ECO-WETstar in BUBA configuration
Turner- 10-AU Field fluorometer
SOO Exercise Results
Turner data was manually recorded
WETStar (BUBA) data was continuous
WETStar data was comparable to Turner data
Peaks indicate when instruments were towed through dye plume
BUBA Features
Synchronized data collection from GPS and fluorometer
Spatial, temporal, and chemistry data merged into single data file
Real time visualization
Color coded ship track on map
Simulated Ship Track with BUBA
Conclusions
In-situ fluorometer are capable of accurate detection of oil plumes in natural environments
Ease of use (i.e. solid state, no field calibration) is a benefit to spill response community
No plumbing required = simplified and fast deployments