The assessment of the quality of sea water samples was carried out according to biological indicators - the total number of microorganisms, which react sharply to changes in their environment. To ensure control over the ecological state of the aquatic environment, it is necessary to conduct regular monitoring studies on such microbiological indicators as the total number of microorganisms. Conventional microbiological methods for determining the total number of microorganisms are laborious and require a well-equipped laboratory and qualified personnel, and such analysis usually takes 24-48 hours. For a comparative assessment of the quality of sea water samples, the number of microorganisms was recorded by traditional methods and by the express method of chemiluminescence. As traditional methods, the method of inoculation on nutrient media, counting on a fluorescent microscope and on colored membrane filters were chosen. A chemiluminescent method was chosen for the rapid assessment of water by the total microbial abundance, which makes it possible to measure the content of bacterial cells by their ATP content. It is shown that the chemiluminescent method is superior to traditional methods for determining the total bacterial contamination (TBC, one of the main indicators of the natural object quality). At the same time, the chemiluminescent reaction made it possible to significantly reduce the measurement time and speed up data processing (measurement time did not exceed 2.5 min), i.e., it became possible to quickly analyze the samples under study in the field and in mobile laboratories. Direct positive correlations between the data determined by the traditional and new methods are revealed. The results obtained in the framework of a study on the determination of the number of microorganisms by classical methods and the chemiluminescence method allow us to recommend their use for express assessment of the quality of various natural objects.

The paper focuses upon the control over environmental pollution of water bodies by human waste products in urban areas, which can be carried out by monitoring hydrobiological indi-cators. In the course of study undertaken in May 2017 and 2018 there was assessed the ecological and sanitary status of the Volga and Kutum rivers that flow on the territory of Astrakhan. Samples were taken at four stations; the choice of station location was determined by the presence of pollutant sources: proximity of the city market or the power plant. Quantitative and qualitative indicators of the state of phytoplankton were used as hydrobiological indicators; the total number of bacteria and the total content of coliform bacteria were evaluated as microbiological indicators. During the study period the ecological and sanitary state of water was rated as satisfactory. The number of algae taxa increased insignificantly (by 3 units), diatoms predominated in the number of genera and number. Despite the presence of 4-5 species of pure water representatives in the investigated waters, the sanitary and bacteriological situation at all the studied stations was found unfavorable; the water was characterized as polluted and dirty. In 2018, there was registered deterioration of water quality compared to 2017, while the calculated saprobity index in the Kutum river indicates the water quality improvement downstream. The increasing value of the water saprobity index in the Kutum river indicates a tendency toward the growing level of organic pollution and necessitates a comprehensive analysis of hydrobiological indicators for systematic monitoring the aquatic environment.