Dynamics of riverbank ephemeral plant communities in the Stryzhen’ river estuary (Chernihiv, Ukraine)

The authors investigated the dynamics of ephemeral plant communities in the Stryzhen’ river estuary (N51°29’17’’, E31°18’57’’; Chernihiv, Ukraine; Eastern Polesia) after exposure to stress factors. The study of plant communities was carried out with generally accepted geobotanical methods. Samples of soil and water were analysed (in laboratory) using colorimetric methods and stripping voltammetry. The research shows that edaphic and hydrological conditions in the riverside alluvial sediment near the Stryzhen’ river estuary have changed under the influence of meteorological factors (mainly rainfalls). These changes have induced vegetation succession. In the monitored area, we observed a decrease in the concentration of nitrate, an increase in ammonia nitrogen content, the accumulation of sulphates, phosphates and salts of Zn2+, Pb2+, Cu2+, which came from rainfall and melt water. The accumulation of heavy metal salts did not reduce the formation of plant communities. The prognosis of further vegetation changes in the monitored alluvial area has been made. An increase in the area of communities on rich, low salified soils (order Agrostietalia stoloniferae Oberdorfer in Oberdorfer et al. 1967) is anticipated. Locations of Crypsis schoenoides (L.) Lam. and Dichostylis micheliana (L.) Nees. were identified for the first time in the Chernihiv region. Diaspora of these plants arrived in the Stryzhen’ river estuary through hydrochory along the northwest migratory route and the upper river that originates near the border of Ukraine and Belarus

Prediction on the content of radionuclides and heavy metals of the Solidago canadensis L. use as a honey resource in Polesie

In the context of the problem of the rational use of the meadow ecosystems of Polesie, which have been exposed to radioactive effect and have not been used economically for a long time, the indicators of radionuclides and heavy metals in soil and plants predict the possibility of using Solidago canadensis L. as a honey resource in summer and autumn periods. The article presents new research results in the direction of studying the species specificity of plants for the accumulation of radionuclides and heavy metals, which are aimed at solving the problem of obtaining the environmentally friendly bee-keeping products from non-traditional honey resources. The habitats of Solidago canadensis were studied in the floodplain of the Dnieper river, its tributaries of various orders and loess “islands” in Polesie – the transformed meadow ecosystems, phytocenoses of which belong to the Molinio-Arrhenatheretea R.Tx. 1937 class, and the ruderal Artemisietea vulgaris Lohmeyer et al. in Tx. ex von Rochow 1951 communities. The content of the radionuclides (137Cs та 90Sr) and heavy metals (Zn, Cd, Pb, Cu) in the soil and inflorescences of Solidago canadensis of 18 sites were analyzed. 11 sites of them, that were not contaminated by the Chernobyl disaster, were analyzed for honey samples. The linear regression equations for honey-plant and honey-soil systems, Pearson’s correlation coefficient (r), significance level (p) and the determination coefficient (r2) for predicting (by indicators of radionuclides and heavy metals in soil and plant) the possibility of honey gathering have been determined. According to the predicted indicators of the heavy metal content and specific activity of radionuclides, it was found that only the meadow ecosystems in the floodplain of the Iput river (the Zalissia village, Dobruskyi district, Gomel region, Belarus) out of 7 studied sites, which were exposed to radioactive contamination in 1986, are suitable for gathering goldenrod honey. In the case of honey gathering on the infested with the Canadian goldenrod meadows in the floodplains of the Dnieper, Sozh and Pakulka rivers, the maximum permissible concentration of cadmium or radionuclides in the products may exceed. It is emphasized that to assess the possibility of obtaining the environmentally friendly goldenrod honey, it is advisable to predict the content of radionuclides and heavy metals in both plants and soil. To do this, it is also necessary to take into account the calculated values ​​of the highest content of heavy metals and the specific activity of radionuclides in soil and plants, at which the metal content in honey will be at the level of the maximum permissible concentration (MPC)