Notes from the Lab


STUDYING COASTAL WATERS WITH NEW TOOLS

The dynamic flow of some coastal waters makes them very hard to study. Teams of ocean researchers brought new oceanographic tools to bear on the problem last June in the Haro Strait off Vancouver Island. These tools included moored buoys and robotic submarines, all of which used sound pulses to explore and communicate.

The researchers mapped rapidly changing currents and demonstrated acoustic communications in a network and from vehicles to the network as well as controlling the vehicles with sound. The experiment also established pioneering procedures for monitoring the effect of underwater sound on the area's marine mammals, ensuring that they were undisturbed by the experiment.

The researchers are from MIT, the Woods Hole Oceanographic Institution, the Institute of Ocean Sciences, and the University of Victoria, BC. Professor Henrik Schmidt of the Department of Ocean Engineering led the MIT and WHOI program; David Farmer headed the IOS team. James Bellingham, manager of the MIT Sea Grant Autonomous Underwater Vehicles Laboratory, led underwater vehicle operations. Funding was from the Office of Naval Research, the MIT Sea Grant College Program, the National Ocean and Atmospheric Administration and the NSF. For more information, see MIT Tech Talk, September 15, 1996. (Source: Carolyn Levi, MIT Sea Grant).

LOOKING AT POLLUTANTS IN GROUNDWATER

In work that could lead to better ways of cleaning up certain pollutants from groundwater, MIT researchers are looking at the interactions between those pollutants and the soils and water through which they move.

Groundwater contaminants like carbon tetrachloride that are in the form of nonaqueous phase liquids (NAPLs) are extremely challenging to clean up, because the behavior of NAPLs in the subsurface is very complex. Researchers led by Professor Patricia Culligan-Hensley of the Department of Civil and Environmental Engineering are exploring that behavior via several different projects.

In one, they are investigating how dense NAPLs migrate in bedrock systems. When such an NAPL enters the subsurface and falls under its own weight to an impermeable barrier such as bedrock, it will have enough force to actually push itself into fractures in the rock, where it becomes difficult to detect and to predict where it might move next. Using a special centrifuge to model the problem, the researchers are looking at how the NAPL moves into the fracture system under different gravitational forces. The work is sponsored by the EPA's Northeast Hazardous Substance Research Center. (Source: Debbie Levey, Civil and Environmental Engineering at MIT).

A version of this article appeared in MIT Tech Talk on October 23, 1996.


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