Courtesy of Water Encyclopedia
Air and water, the most vital elements for our survival as a species, are also the swiftest and deadliest transmitters of contaminants and pollutants. They are the most susceptible to contamination due to natural disasters, industrial spillage, and even sabotage, capable of wiping out scores of living beings in one sweeping onslaught and rendering us almost defenseless.
Most often the consequences of contamination are catastrophic because of the time lapse before the onset of contamination can be detected. This leaves very little scope for forewarning even with periodic checks in place, and widespread illnesses and deaths invariably serve as the first indicator of the prevailing danger.
Under such circumstances, our best bet is to equip our potable water supply networks with a real-time monitoring system that can watch out for contaminants creeping into the system, raise the red flag instantaneously, and prevent any further damage.
Professor Abraham Katzir of Tel Aviv University’s School of Physics and Astronomy has developed a sensor based on infrared spectroscopy that can be used to monitor our potable water supplies. Equipped with specially modified silver halide fibers, the sensor head is placed in a stream of flowing water and these fibers continuously detect ‘colors’ in the infrared spectrum to differentiate between pure and contaminated water. The infrared spectrum is not visible to the naked human eye but can be perceived by animals—such as vampire bats and snakes, which use this ability to track down prey.
Under laboratory conditions, the fiber-optic sensor system was able to detect the presence of toxins, such as pesticides, in amounts well below the safety threshold prescribed by the World Health Organization. Professor Katzir assures that the fiber sensors themselves are made of non-toxic, insoluble and biocompatible materials, and do not contaminate water in any way.
Research articles published in the Journal of Applied Spectroscopy provide details on field experiments conducted to test the efficacy of these silver halide fibers in detecting the presence of hydrocarbons in water, and in in-situ sensing of volatile organic compounds in groundwater. Here are some interesting observations gleaned from the abstracts provided online. Experiments revealed that the sensitivity of these silver halide fibers increased significantly when they were flattened and coated with an organic polymer before use. Apparently, a flattened fiber with a thickness of 170 microns was five times as sensitive as a fiber with a thickness of 900 microns! In another experiment, the fiber-optic sensor was able to clearly detect dichlorobenzene, diethyl phthalate, tetrachloroethylene, and xylene isomers present in a sample of flowing water at concentrations of low parts per million (ppm).
Although water reservoirs in our country are periodically tested, they are not equipped with systems to detect chemical threats instantaneously. This makes our potable water supply network extremely susceptible to chemo-terrorist attacks. An instantaneous monitoring, detection and warning system could also reduce the costs incurred in manual testing of water in addition to eliminating measurement errors inherent with manual testing.
Water management executives in Everglades, Florida, and officials in Germany are likely to be among the first users of this technology. In January 2007, Professor Katzir met with scientists of the South Florida Water Management District (SFWMD)to discuss methods for monitoring water pollution in the Everglades and Lake Okeechobee regions, and in groundwater in South Florida. A collaborative project between Professor Katzir’s Applied Physics Lab at Tel Aviv University and the Florida Center for Environmental Studies at Florida Atlantic University, with support from the Florida-Israel Institute, is currently in progress. Professor Katzir’s water monitoring system is expected to be ready for large-scale commercial use in less than a year.
Apparently, Professor Katzir’s crusade against terrorism stems not only from professional interest but also finds roots in a personal tragedy. His father, Professor Aharon Katzir, was one of the victims of the Lod Airport massacre, a terrorist attack launched by the Japanese Red Army at Tel Aviv in May 1972, leaving 24 dead and 80 more injured.
Professor Katzir’s real-time water monitoring solution could very well be a shot in the arm to the United States’ efforts towards building up its defenses against terrorist attacks.
