Microbiological Quality, Ecological Status, and Potential Sources of Contamination of the River Water

Abstract

Surface water contamination becomes a raising problem due to different anthropogenic factors such as agriculture, industry, waste landfills, and wastewater effluents. Small rivers are also exposed to wastewater influents, pollution from agricultural activities, as well as raising human influence on the river flow (dam building). This research aimed to analyze the microbiological quality and ecological status of the water on the small river Ribnica in Western Serbia. Ribnica is a 22 km long tributary of Kolubara. The upper part of the river flow is surrounded by forests, agricultural fields, and small farms. Downstream, the river flows through Mionica, a small town where its water quality becomes endangered by communal wastewater, as well as landfills in the river surrounding. The microbiological quality of river water was estimated by the presence of coliforms, E. coli, enterococci which determination was done by Colilert and Enterolert method (IDEXX Laboratories, USA). The other parameters for water ecological status (oligotrophs, heterotrophs microorganisms, and autopurification index) are determined using the serial dilution method and incubation on selective nutrient media. The index of autopurification was calculated as oligotrophs/heterotrophs ratio. Our results show that the greatest pollution comes in the river after Mionica center. The extremely large number of fecal E. coli indicates the presence of fecal matter in water which could be a potential risk for human health if this water is used for irrigation crops or recreation. Also, autopurification index of water in this location indicates very poor self-purification potential which means that this water needs human help for achieving good ecological status. Regular monitoring and analyses of microbiological contamination and ecosystem disturbances should be important input data for public policies and strategic planning in the area of wastewater management, hydraulic engineering, and agricultural management.