Search Results (6)

Dibutyl phthalate (DBP) is widely used as a plasticizer in the production of polymeric materials to give them flexibility, strength and extensibility. However, due to its negative impact on human health, in particular reproductive functions and fetal development, the content of DBP must be controlled in food and the environment. The present study aims to develop a sensitive, fast and simple fluorescence polarization immunoassay (FPIA) using monoclonal antibodies derived against DBP (MAb-DBP) for its detection in open waters. New conjugates of DBP with various fluorescein derivatives were obtained and characterized: 5-aminomethylfluorescein (AMF) and dichlorotriazinylaminofluorescein (DTAF). The advantages of using the DBP-AMF conjugate in the FPIA method are shown, the kinetics of binding of this chemical with antibodies are studied, the analysis is optimized, and the concentration of monoclonal antibodies is selected for sensitivity analysis—16 nM. The calibration dependence of the fluorescence polarization signal for the detection of DBP was obtained. The observed IC50 (DBP concentration at which a 50% decrease in the fluorescence polarization signal occurs, 40 ng/mL) and the limit of detection (LOD, 7.5 ng/mL) values were improved by a factor of 45 over the previously described FPIA using polyclonal antibodies. This technique was tested by the recovery method, and the high percentage of DBP discovery in water ranged from 85 to 110%. Using the developed method, real water samples from Lake Onega were tested, and a good correlation was shown between the results of the determination of DBP by the FPIA method and GC-MS. Thus, the FPIA method developed in this work can be used to determine DBP in open-water reservoirs. Full article

Macrolide antibiotics, which are effective antimicrobial agents, are intensively used in human and veterinary medicine, as well as in agriculture. Consequently, they are found all over the world as environmental pollutants, causing harm to sensitive ecological communities and provoking a selection of resistant forms. A novel azithromycin derivative, which was used as hapten conjugate, ensured the group immunorecognition of six major macrolide representatives (105–41%), namely erythromycin, erythromycin ethylsuccinate, clarithromycin, roxithromycin, azithromycin, and dirithromycin in a competitive immunoassay based on anti-clarithromycin antibodies. The heterologous hapten-based ELISA format resulted in a 5-fold increase in sensitivity, with an IC₅₀ value of 0.04 ng/mL for erythromycin. In this study, we proposed an underexploited strategy in an immunoassay field to significantly improve the detectability of analytes in environmental samples. Unlike most approaches, it does not require special enhancers/amplifiers or additional concentration/extraction procedures; instead, it involves analyzing a larger volume of test samples. A gradual volume increase in the samples (from 0.025 to 10 mL) analyzed using a direct competitive ELISA, immunobeads, and immunofiltration assay formats based on the same reagents resulted in a significant improvement (more than 50-fold) in assay sensitivity and detection limit up to 5 and 1 pg/mL, respectively. The suitability of the test for detecting the macrolide contamination of natural water was confirmed by the recovery of macrolides from spiked blank samples (71.7–141.3%). During 2022–2023, a series of natural water samples from Lake Onega and its influents near Petrozavodsk were analyzed, using both the developed immunoassay and HPLC-MS/MS. The results revealed no contamination of macrolide antibiotic. Full article

In 2009–2018, the isotopic composition of oxygen and hydrogen in the atmospheric precipitation, groundwater and river and lake water of Lake Onega basin was studied. The weighted annual isotope composition of precipitation at Petrozavodsk was δ¹⁸O = −11.7‰ and δ²H = −84‰ and varied from −30.9 to −4.1‰ for δ¹⁸O and from −23 to −22‰ for δ²H. The isotopic composition of the water in Lake Onega was relatively uniform from −11.5 to −9.3‰ for δ¹⁸O and from −85 to −71‰ for δ²H. In the bays, the isotopic composition of the water varied more substantially than in the central part of the lake due to the river runoff during springtime flooding. In late summer, the concentrations of deuterium and oxygen-18 increased in the lake water, and figurative points on the δ²H vs. δ¹⁸O diagram shifted above the meteoric line. The absorption of the isotopically heavy summer precipitation and disequilibrium isotope fractionation during evaporation led to the enrichment of the lake water by heavy isotopes. Experiments were conducted to estimate the evaporation influence on the isotope enrichment of the residual water, and a comparison of the obtained isotope data with the experimental function showed that commonly, about 4% and up to 12% of water was lost during the spring and summer, respectively. In the water of the tributaries, the abundance of the deuterium and oxygen-18 varied in a wider scale than in the lakes, from −14.4 to −9.1‰ for δ¹⁸O and from −102 to −73‰ for δ²H. An evaporation loss of up to 35% was found for the rivers in late summer, and this value was proportional to the area of lakes and wetlands in the elementary watershed. The initial isotope composition of the water in the tributaries prior to evaporation was estimated to be δ¹⁸O ≈ −14.1‰ and δ²H ≈ −103‰ on average and crossed the approximation and meteoric lines. This estimation was close to the average composition of the groundwater, i.e., δ¹⁸O ≈ −13.4‰ and δ²H ≈ −94‰ on the Lake Onega catchment. The slightly increased isotope depletion of the calculated composition in the initial river water in comparison with the groundwater was the result of the contribution of the spring snowmelt water, which had a significant influence on the lake water balance. Full article

The article presents data on the analysis of U accumulation in recent sediments of lakes in the territory of the Southeast Fennoscandia. The research was carried out in the study area of the Republic of Karelia. It has been established that the content of U in sediments varies from 0.1 to 42.3 mg/kg (median is 0.91 mg/kg). In general, the studied sediments of the region had low concentrations of U in comparison with the average content of this element in the upper part of the Earth’s crust. In some areas associated with deposits or ore occurrences of U, an increased content of U in lake sediments was revealed. The highest U accumulation level was found in the lake sediments, which are under the influence of the North Onega ore-geochemical region, where V deposits and ore occurrences that contain U, Fe, Mo and Cu are widespread. In the sediments of some studied lakes, Th anomalies were found, which often accompany U in ore geological formations. The analysis of uranium fractions in the sediments of some lakes in Karelia revealed the key role of the mineral (insoluble) phase in the accumulation of U, up to 64–68% of the total U content. The share of the organic fraction in the accumulation of U in the studied sediments of the lakes is small and ranges from 7 to 15% with respect to the total concentration of the metal. Full article

Regional climate change affects the state of inland water bodies and their water balance, which is determined by a number of hydrometeorological and hydrogeological factors. An integral characteristic of changes in the water balance is the behavior of the level of lakes and reservoirs, which not only largely determines the physical and ecological state of water bodies, but also significantly affects the coastal infrastructure and socio-economic development of the region. This paper investigates the interannual variability of the level of the Ladoga and Onega lakes, the largest lakes in Europe located in the northwest of Russia, according to satellite altimetry data for 1993–2020. For this purpose, we used three specialized altimetry databases: DAHITI, G-REALM, and HYDROWEB. Water level data from these altimetry databases were compared with in-situ records at water level gauge stations. Information on air temperature (1945–2019) and precipitation (1966–2019) acquired at three meteostations located at Ladoga and Onega lakes was used to investigate interannual trends in the regional climate change. Finally, we discuss the potential impact of the lake level rise and regional climate warming on the infrastructure and operability of railways in this region. Full article

In this paper, retrospective analyses of long-term changes in the aquatic ecosystem of Ladoga, Onega, and Imandra lakes, situated within North-West Russia, are presented. At the beginning of the last century, the lakes were oligotrophic, freshwater and similar in origin in terms of the chemical composition of waters and aquatic fauna. Three stages were identified in this study: reference condition, intensive pollution and degradation, and decreasing pollution and revitalization. Similar changes in polluted bays were detected, for which a significant decrease in their oligotrophic nature, the dominance of eurybiont species, their biodiversity under toxic substances and nutrients, were noted. The lakes have been recolonized by northern species following pollution reduction over the past 20 years. There have been replacements in dominant complexes, an increase in the biodiversity of communities, with the emergence of more southern forms of introduced species. The path of ecosystem transformation during and after the anthropogenic stress compares with the regularities of ecosystem successions: from the natural state through the developmental stage to a more stable mature modification, with significantly different natural characteristics. A peculiarity of the newly formed ecosystems is the change in structure and the higher productivity of biological communities, explained by the stability of the newly formed biogeochemical nutrient cycles, as well as climate warming. Full article