Assessment of the ecological status of freshwater bodies of the Kaliningrad region in 2018 by hydrochemical and microbiological indicators
A study of the state of the Pregolya and Neman rivers, Vishtynec lake, the Pravdinsk reservoir on chemical and microbiological indicators was carried out in 2018 as part of the state monitoring of the habitat of aquatic biological resources (ABR). Samples were taken from March to October, the following indicators were investigated: pH and biochemical oxygen demanding (BOD5), dissolved oxygen content, nutrients concentrations, anionic surfactants, oil products, organic pollutants, micro- and macroelements, as well as microbiological indicators and saprobity index. BOD5 throughout the entire period of observation (except for values in the Pregolya River in June) exceeded maximum permissible concentration (MPC). The excess was also observed for ammonium nitrogen in the Pregolya river (in June), Pravdinsk reservoir (in June and August) and nitrite nitrogen - in the Pravdinsk reservoir (in June). An insignificant excess in nitrite nitrogen values was during the whole year in the Pregolya and Neman rivers. The MPC excess for organochlorine pesticides was noted for the investigated water bodies. The content of polychlorinated biphenyls in water bodies was 19-52 of MPC values, polyaromatic hydrocarbons - from 7 to 224 ng/dm3, waters of the Pregolya and Neman rivers can be described as contaminated considering polyaromatic hydrocarbons concentrations. For all investigated water objects, an excess of copper, manganese and iron concentrations was observed. The excess of mercury content in the Neman river in June was 40 MPC. Total number of bacteria was the highest in the Neman River, the lowest one - in the Vishtynec Lake. Indices of self-purifications for all studied water bodies were considered as satisfactory. Based on microbiological indices of water quality, in 2018 the water of the Pregolya and the Neman rivers were classified as alfa-mezosaprobic (attributed to 4 class of the water quality) as well as the water of the Pravdinsk reservoir- as beta- alfa- mezosaprobic (3-4 classes of water quality), and water of Vishtynec Lake- as beta-mezosaprobic (2-3 classes of the water quality).