Monitoring of the River Rhein — Experience Gathered from Accidental Events in 1986

Water quality of the river Rhein has been gradually improved in comparison to the situation in the 7oies. Thus more sensitive aquatic organisms are now settled in the water body and the banks of Rhein river. Therefore accidental events are now more important for the river possibly deteriorating the water quality. Even more important, drinking water supply may be endangered especially by those substances which are not eliminated in the purification process. In 1986, a number of contaminations of the Rhein water were reported, most of them caused by accidents in chemical production plants. The monitoring strategy for the Rhein in Nordrhein-Westfalen has proven to be succesful, the monitoring system should be enhanced.For rapid detection of contaminants in the river, monitoring activities include sensitive chemical screening methods as well as biological tests. In order to control waste water and cooling water discharge, automized analytical systems should be installed directly at the discharge points of a chemical production plant to detect irregularities as fast as possible. Moreover chemical companies should be enforced to install samplers working automatically. As decisions have to be taken very quickly, valid data on the behaviour of all possible and relevant contaminants with respect to raw water purification should be available on-line.