Detailed information of the status of pollution of any water body is of much importance because it ultimately helps in the proper management of these waters. A physico-chemical approach to monitor water pollution is most common and plenty of information is available on these aspects. Such data usually provides a mosaic picture of the whole scenario. Chemical analysis is valuable and necessary, but does not provide all the information required in pollution assessment. It is not the contamination that are concerned, but rather the effects of their concentrations on organisms. It is only by documenting these effects that the true effects are defined. Analysis of a particular chemical is directed towards a specific contaminant and its expression will be a union of other contaminants that is not in the suspected list. It is thus possible that a key toxic contaminant may be overlooked and so a supplementary pollution study is most essential.

One of the most striking features of the past water assessment procedures has been reliance placed upon physical and chemical techniques; with relative neglect of biological parameters. Since water pollution is in many instances a biological phenomenon, it would appear logical that it ought to be measured biologically. Biological indicators show the degree of ecological imbalance that has been caused and chemical methods measure the concentration of pollutants responsible. The majority of lake systems of biological assessment have been devised mainly to deal with conditions arising out of organic pollution. Chemically the effects to measure all the organic pollution are rather difficult to monitor. It is not possible to measure all the organic compounds directly and even though the BOD test provides an insight into their rates of oxygen consumption, this only measures one component of the complex oxygen balance. Assessment of solids pollution in lakes that receive continuous sewage can be very damaging mainly due to siltation, which may be considerably exacerbated by deoxygenation when the solids are organic. One of the difficulties in making the exact assessment of organic pollution is the lack of any absolute scale of measurement.

Department of Studies in Botany,
University of Mysore,
Manasagangotri,Mysore – 570 006,
Karnataka. India.