Comparative Characteristics of Quality Parameters of Waters of the Oka River in Places of Water Intake of Utility and Drinking Water System in Ryazan

INTRODUCTION: Surface water sources play an important role in supply of large cities with water. Their waters are subject to anthropogenic pollution with different chemical compounds which may be significant risk factors for the health of the population. The article presents the results of comparative sanitary-hygienic characteristics of the water quality of the Oka river in places of water intake of utility and drinking water supply system of Ryazan. Being the only surface source of water supply, the Oka river provides 53% of the total water consumption of the Ryazan population, therefore a rational choice of the place of water intake can have a considerable impact on the effectiveness of water conditioning and purification and on the final quality of drinking water. 
AIM: To give a comparative sanitary-hygienic characteristic of the water quality of the Oka river in places of the water intake of the utility and drinking water supply system of Ryazan. 
MATERIALS AND METHODS: A comparative evaluation of the water quality of the Oka river, as a surface source of water supply, was carried out based on the average long-term values of control parameters (organoleptic, microbiological, chemical) and the proportion of samples that do not meet hygienic standards in the sections of three water intakes in Ryazan in 20122019. The average parameters were compared by the method of variance analysis; for paired comparisons, Scheffe and Tamhein criteria were used, taking into account the results of Levene test. The statistical parameters were calculated in SPSS Statistics 19 program. 
RESULTS: The chemical composition of the Oka river water was characterized by the greatest pollution with iron (2+) and aluminum. The water of Oksky and Borkovskoy water intakes was characterized by higher average concentrations of iron (2+) and ammonia, as well as greater contamination with generalized and thermotolerant coliform bacteria, compared with the water of Sokolovsky water intake. 
CONCLUSION: A lower initial quality of the water in Oksky and Borkovskoy water intakes may be due to their location in the 'blind' river course characterized by the processes of eutrophication and slowed down water exchange. High concentrations of iron (2+) may be associated with supply of stream water from the underground sources or with anthropogenic pollution.