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