A Brief Review of Chemical and Biological Continuous Monitoring of Rivers in Europe and Asia

The continuous chemical and biological monitoring in Europe dates back to the sixties and seventies. After three decades of development there are a number of reliable chemical monitoring systems for river monitoring, but biological monitoring is still in the stages of infancy (Baldwin and Kramer, 1994; Kramer and Botterweg, 1994;Gunatilaka et al., 2000). However it is a fast developing field with the availability of powerful tools from biochemistry, molecular biology and genetics. At the molecular level the developments are only two decades old. Research and development has stimulated development of a series of novel on-line sensors which are quite promising and different to conventional sensors (seeCowell, 2000;Scully et al., 2000;Girotti et al., 1993, 1992; Roda, 1989). Increased reliability requirements has stimulated research into non-invasive sensor techniques using laser technology and into optical sensors. The non-invasive laser sensor has the advantage of not being prone to fouling, freedom from electromagnetic interference and of being less susceptible to corrosion (Meredith, 1997). Optical sensors are promising and it is a fast emerging branch in the monitoring technology (Scully et al., 2000; Zhang et al., 1996;Bruno et al., 1995).