Bay researchers intend to stir things up

December 09, 1990|By Mark Di Vincenzo | Mark Di Vincenzo,Newport News Daily Press

GLOUCESTER POINT, Va. -- At Gloucester Point, inside a haunted-looking, 70-year-old house and what was once its garage, a team of marine scientists are immersing themselves in mud.

The scientists, from the Virginia Institute of Marine Science's Division of Geological and Benthic Oceanography, have received a two-year, $218,914 grant from the U.S. Environmental Protection Agency to study the interactions of water and mud at the bottom of the Chesapeake Bay, one facet of bay activity about which very little is known.

"In terms of cohesive sediments,we have a helluva long way to go," said Robert J. Byrne, associate director of research at VIMS.

Knowing more about the movement of mud, or "cohesive sediment dynamics," the scientists hope, will help them give better advice about improving water quality and curbing erosion, among other things.

The success of the research depends on the effectiveness of their data gatherer: a $50,000 homemade, motor-powered, 8-foot, 700-pound, aluminum, doughnut-shaped device that will be dunked in the York River for the first time in the spring.

"Not much is new here," said its primary creator, Jerome P. Y. Maa, known as the Mud Man because of his vast knowledge of mud. "Aluminum is not new. Motors are not new. The idea is new."

Similar machines, generically called "sea bed flumes," are in use in five laboratories worldwide -- three in the United States and one each in China and Japan, Mr. Maa said. But only one other, at the Bedford Institute of Oceanography in the Bay of Fundy in Canada, is used in a natural, outdoor laboratory.

However, the Bedford flume, first submerged in 1989, gathers data for scientists studying the movement of sand, not mud, making the VIMS flume unique in its mission.

Canadian scientists as well as those at VIMS say a sea bed flume is the perfect tool to study bay, river and sea bottoms because they effectively reproduce underwater flow, stirring sediments as naturally as a machine can while gathering data about the particles.

The first flume, a straight one, was used by scientists in 1982 at Woods Hole Oceanographic Institute in Massachusetts.

The VIMS flume will be underwater for two or three days at a time, with its motor constantly running, Mr. Maa said. He first proposed the idea shortly after his arrival at the marine science institute in 1987 and completed the design last year.

Yet to be finished, it should work like this:

A motor, sealed with a watertight cover, activates steel chains that resemble large bicycle chains. The chains move a flume cover that rotates atop the stationary, doughnut-shaped flume. Much like the open palm of a hand drawn flat across the top of a water surface, the rotating flume cover creates a gentle current that stirs sediment up on the river bottom.

If the cover moves properly, it creates water flow similar to the underwater flow in the bay.

An optic sensor affixed to the inside of the flume gathers data about sediment movement inside the flume; that data is fed into computers in the marine science institute's Hoxton Hall and its annex. The scientists hope that the data will help them answer questions about:

* How dredging projects affect bay and river bottoms.

* How water moves mud.

* How bay and river bottoms -- and their depressions and slopes -- affect the way water moves ashore, causing erosion.

* What happens to toxic substances, like the pesticide kepone -- which after being dumped into the James River by a Hopewell, Va., company forced the closure of fishing in the river from 1975 to 1988 -- after they are absorbed in mud.

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