Danube quality water assessment from the microbiological point of view in Cernavoda nuclear plant area

Herein are analysed the following microbiological parameters: total viable count, total coliforms and faecal coliforms, which represent a standard indicator for water quality. The study has been done during 1998-2002 upon the water in the Danube River and in the channels for cooling water used by Cernavoda Nuclear Power Plant condensers. In this area, based on these values of evaluated parameters, the water feature is placed in the quality classes II and III (moderate and critical pollution), in conformity with European Community Directives. Bacterial communities, component part of aquatic biocenoses, are very important for matter and energy flux. Their contribution to self-purification processes of rivers is of great interest related to the water quality assessment. Microorganisms are ideal sensors, because they respond fast to the fluctuation of environmental conditions by specific changes, detectable physiologically and metabolically. The temperature is a major factor, which directly affects the intensity of all microbial processes. Because the microorganisms are interconnected with the other living organisms, the qualitative or quantitative changes of their activity will affect the functions of the whole ecosystem. Bacterial indicators such as total viable count (colony count), total coliforms or faecal coliforms (thermo-tolerant coliforms) are widely applied to the assessment of water quality. Because of their mostly allochthonus origin, these are used as indicators of changes in the natural water conditions; they point out an organic matter or faecal water pollution. Although the water quality can be considered acceptable from the chemical or biological point of view, the bacteriological parameters might be detected in critical concentration. The objectives of this microbiological assessment are analysis of the variation of bacteriological indicators in some sampling points of Cernavoda aquatic ecosystems area, and monitoring the manner of using the water by cooling systems in the nuclear power plant. (author)