USF researchers build sensor to detect underwater TNT

In a study published in Sensors and Actuators B: Chemical (v 106 no.1), University of South Florida College of Marine Science researchers in the Center for Ocean Technology (COT) explained their recent development of a sensor that can detect the explosive 2,4,6-trinitrotoluene (TNT) in a marine environment.

"Explosive residue in water, mostly from the use and disposal of explosive substances of the last 100 years, is a significant environmental problem," said David Fries, co-author of the study and COT researcher. "However, recent anti-terrorism efforts have placed a high priority on detecting TNT in the marine environment. With interest in port security rising, detecting explosive residue in the water is essential."

According to Fries, the newly developed sensor is a scanning voltammetry-based electrochemical sensor that uses electrochemical means to detect explosive residues. It is a self-contained system that uses an electrochemical electrode to sense for trace TNT. Researchers took into account the fact that TNT in seawater undergoes biodegradation in a number of different ways and accounted for those processes in developing the sensor.

The sensor has been designed to detect several kinds of commercial and military explosives while riding on a remotely controlled guided surface vehicle (GSV) that wirelessly transmits data to a handheld computer.

The system has been tested in the field under a number of conditions, including turbulent waters. In field tests, the new sensor was mounted on the GSV, a six foot long, 175 pound vehicle built by USF chemistry professor Eric Steimle. The GSV can also be fitted with video cameras, global positioning system (GPS), other chemical and biological sensors and wireless equipment for sending data. Steimle built the GSV from everyday materials available at hardware stores and has piggy-backed a great variety of equipment for USF marine studies.

"This mobile, intelligent sensor platform permits the operator to be 'in the loop' and make real time decisions during chemical surveys," said Fries. "It addresses the growing demand for in-place, continuous TNT measurement. It is also an approach that can be extended to other kinds of explosives."

Fries' co-researcher from the University of South Florida is Xiaojuan Fu. The work was supported by a grant from the Office of Naval Research.

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This article originally appeared in the 05/01/2005 issue of Environmental Protection.