Dibutyl Phthalate in the Water of Kondopoga Bay and Some Tributaries of Lake Onega

An assessment was made of the pollution of the Kondopoga Bay and small tributaries of Lake Onega with dibutyl phthalate, the most common and industrially used ester of phthalic acid. Water samples were analyzed for the content of organic matter, nutrients, heavy metals, lignosulfonates, and the ionic composition of water. The concentration of dibutyl phthalate was determined by gas chromatography and mass spectrometry. Sampling was carried out during the ice-covered period in March 2023 in the waters of the Kondopoga Bay of Lake Onega, exposed to the influence of wastewater from the Kondopoga Pulp and Paper Mill, and a number of small watercourses in the vicinity of Petrozavodsk, receiving wastewaters from residential areas and waste disposal sites. It was found that the average dibutyl phthalate content in the Kondopoga Bay water area is 6.7 μg/L, while in small tributaries it is slightly higher, averaging 11.9 μg/L. All analyzed samples showed an excess of the maximum permissible concentration for dibutyl phthalate in fishery waters (1 μg/L). At the same time, no statistically significant relationships were found between the dibutyl phthalate content and wastewater marker components (lignosulfonates, nutrients). Statistically significant relationships were found between the dibutyl phthalate concentration and the content of lithophilic elements (Fe, Mn, Si), as well as organic substances of natural origin (by color index, total organic carbon, dissolved organic carbon, chemical oxygen demand), indicating their joint entry from the catchment area. It has been established that the Kondopoga Pulp and Paper Mill has no significant effect on the dibutyl phthalate content in the Kondopoga Bay of Lake Onega, and its sources of entry into the lake are mainly atmospheric precipitation, surface and river runoff. The increased dibutyl phthalate content in the organic matter-saturated river waters of the boreal zone may be partly of natural origin. The pollution of Lake Onega and its small tributaries with dibutyl phthalate revealed in the course of this study is comparable to the previously studied pollution of water bodies in Russia and other countries.