much water has flown under the bridge in an attempt to develop a technology that will determine levels of pollution in rivers. Now, a new laser-based technology has been introduced in the uk to perform this task in English rivers and monitor discharges from chemical works and sewage into the country's waterways. The laser technique has been developed by Rafi Ahmad of Cranfield University's Centre for Applied Laser Spectroscopy at Bedfordshire and the Water Engineering Research Group at Hertfordshire University, both in southern England.

The ultraviolet lasers can instantly read the nature of pollutants. This method eliminates the traditional mode of analysis by water collection and laboratory testing which usually takes about five days to complete. When the laser focuses on waterbodies and pollutants its sensors immediately register nitrates, chlorides, phosphates and organic waste. The concentration of the latter is used for determining the water's biological oxygen demand (bod), the amount of oxygen consumed by bacteria feeding on it. A high bod level is sure to asphyxiate fish. At present, water companies run water through fish-stocked tanks to ensure it is potable.

Ahmad believes that with further development, the laser system will be in a position to monitor whole rivers or be flown to different areas for checking high levels of pollution off beaches. "We are now working on miniaturising the system and making it cost-effective. If we get a grant, the technology can be made commercially viable in about a year's time. We hope that the costs will not be prohibitive,' he added.

The two universities involved in the project are expecting a grant from uk' s Engineering and Physical Sciences Research Council to turn their experimental laser system into a prototype pollution monitor. The trials have already won approval from the water companies and environmental agencies, which are responsible for rivers in uk .