Voyages of the NOAA Ship Thomas Jefferson
There are many ships at work right now in the Gulf of Mexico responding to the devastating consequences of the Deepwater Horizon explosion. Some are skimming the water to collect oil, some are burning off the oil. Some are busy digging a relief well. However, there is at least one vessel that is using this tragedy as an opportunity to conduct scientific research. The National Oceanic and Atmospheric Administration's (NOAA) ship, Thomas Jefferson, is using acoustic and fluorometric scanning to detect oil under the surface.
The ship set off from Galveston, Texas on an eight day mission into the Gulf of Mexico, and returned to port on June 11. The purpose was to investigate the distribution and presence of subsurface oil coming from the rig explosion. Water samples were collected and analyzed by agency officials and scientists from the University of New Hampshire and the Woods Hole Oceanographic Institution.
"NOAA is extremely concerned about the health of the Gulf of Mexico and the well-being of the millions of people who depend on these waters for their livelihoods and pleasure," said Jane Lubchenco, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. "I'm pleased that agency and academic scientists continue to innovate and explore ways to bring the absolute best science to inform the response and recovery efforts."
First, the science team would sweep the underlying waters with acoustic and fluorometric sensors to detect aberrations in the water column. Then they would take water samples to determine if the aberration was actually oil.
An acoustic sensor uses sound waves and is often referred to as SONAR which is used commonly in submarines. Passive acoustic sensors listen to the sounds in the water. Active sensors emit pulses of sound and then listen for the echo. An oil plume would have different sound reverberation than the water.
Fluorometric sensors use light waves to determine the shape of an oil plume. A beam of light, usually ultraviolet light, is scanned throughout the water. The light can excite electrons of certain molecules and cause them to emit their own light at a lower energy. This is the same concept behind glow-in-the-dark posters or stars that can stick onto a wall. The oil would have different fluorescence than the water.
The Thomas Jefferson made several initial observations including:
1. Subsurface oil was found 7.5 nautical miles southwest of the wellhead at 1,100 meters in depth by observing high fluorescence and reduced dissolved oxygen.
2. An acoustic anomaly was also found in the same area.
3. Natural gas was also found in an area of known gas seepage southwest of the spill site.
4. Fluorometric sensors have shown to be an extremely effective method to detect water masses in shallow waters.
Another expedition is underway for the ship, Thomas Jefferson to gather more data in the coastal zone. Any information on subsurface masses discovered in the coastal zone would be shared with other researchers and emergency responders.
The situation in the Gulf requires an all-hands-on-deck approach, and NOAA is doing its part to provide accurate data on where the oil is. Knowing where to find oil is just as important as cleaning up the oil. The work is sure to be difficult and ongoing.
Link to full NOAA Mission Report