In 2023, the northwestern part of the Black Sea underwent significant ecological changes due to the destruction of the dam of the Kakhovka Hydroelectric Power Plant. The large volume of fresh water with nutrients and the increase in water temperature were responsible for the intensive development of Cyanobacteria and green algae, water bloom in summer, and red tides due to the intensive development of Dinophyta in autumn. Representatives of Bacillariophyta, Dinophyta, Chlorophyta, and Cyanobacteria prevailed. However, their ratio changed significantly under the influence of stress factors. The average monthly phytoplankton numbers in 2023 ranged from 84 thousand cells/L to 4306 thousand cells/L, its biomass - from 0,073 to 3,778 mg/L, and the Shannon diversity index varied in 2023-2024 from 1.10 to 3.58 bits/ind. indicating structural instability of communities in response to extreme hydrological changes. Despite the increasing level of eutrophication and surges in algal numbers and biomass, bioindicators demonstrate signs of phytoplankton adaptation to new conditions and gradual stabilization of the ecosystem. The obtained results indicate the high sensitivity of phytoplankton to hydrological disturbances and emphasize its importance as an indicator group for monitoring aquatic ecosystems under conditions of the technogenic disaster.
Seasonal changes in the concentration of petroleum products, anionic surfactants, and heavy metals in the water of three cascades of ponds of the Golosiyivsky National Nature Park (Ukraine) were studied. A significant increase in the concentration of petroleum products and anionic surfactants in the water of these ponds was registered in summer compared to spring. In autumn, the content of petroleum products decreased in most ponds, but the concentration of anionic surfactants continued to increase. A tendency to a decrease in the concentration of heavy metals in the water of the Kytayevo and Didorivka ponds in summer was revealed. In the water of the Gorikhovatka ponds an increase in the concentration of heavy metals was observed in different seasons, which is associated with a higher level of anthropogenic load on these water bodies.
(Cchl a+b+c/Cchl a, Cchl b/Cchl a, Cchl c/Cchl a, Cchl a/Cchl b, Cchl a/Cchl c, Cpheo a, %, Cchl a/Cpheo a, Ccar/Cchl a, the Margalef index E430/E664, and the pigment ratio E480/E664, E430/E665) of phytoplankton in 12 ponds of the Golosiyivsky National Nature Park (Kyiv, Ukraine), which differ in the level of anthropogenic pollution. It has been found that phytoplankton of the Gorikhovatka ponds compared to that of the Didorivka and Kytayevo ponds was characterized by the higher average values of the total content of pigments, the relative content of chlorophylls a and b, and the ratios Cchl a/B and Cchl a/Cchl c, and by the lower average values of the relative content of chlorophyll c, the ratios Cchl a + b + c/Cchl a, Cchl c/Cchl a, Cchl a/Cchl b, Cchla/Cpheo a, and Ccar/Cchl a, the Margalef index E430/E664, and the pigment ratio E430/E665, while the average values of the ratio of Cchl b/Cchl a were almost the same in all studied pond systems. The lowest average value of the pigment ratio E480/E664 was in the Didorivka ponds and the highest - in the Kytayevo ponds. In terms of the content of chlorophyll a, all studied ponds can be assigned to the eutrophic type, and in terms of phytoplankton biomass - their vast majority (75%).
The article deals with the main hydroecological aspects of termination of the peak regime of the water supply to its lower reaches of the Dnieper River after the destruction of dam of the Kakhovka hydroelectric power station (HEPS) caused by military actions. This resulted in significant decrease of the daily amplitudes of water level fluctuations, which led to drastic decrease of water exchange between the river channel and in the floodplain network. At present, the water exchange period of the lakes of the pre-delta section of the Dnieper increased by 248-748%. The external water exchange of the Dnieper delta water bodies has also reduced, but due to natural differences in water level in the Dnieper-Bug estuary, the reduction in the intensity of water exchange here is 46-200%. Calculations have shown that the most water bodies (81%) currently have the decelerated water exchange (above 15 days), 19% - 3-15 days, there are no water bodies with fast water exchange (less than 3 days). At the beginning of the 21st century, this ratio of water bodies with slow, moderate and fast water exchange was 16, 76 and 8 %, respectively. The main ecological consequences of the total slowdown of the external water exchange of the floodplain water bodies in the Lower Dnieper caused by military operations and the Kakhovka dam destruction are considered, typical hydroecological conditions for each group of water bodies are highlighted.
This study examines how physiñochemical water parameters fluctuate seasonally in a tributary of the Beas River in Himachal Pradesh (the Western Himalayas), with the goal of assessing the degree of water quality deterioration and pinpointing pollution sources. Water samples were collected across four distinct seasons and analyzed using standard protocols for air and water temperature, pH, dissolved oxygen, electrical conductivity, total dissolved solids, total alkalinity, total hardness, chloride, phosphate, nitrate, and silicate. The findings reveal that only water temperature and pH consistently met agency-recommended guidelines; all other parameters exceeded acceptable limits in every season. Duncan's Multiple Range Test (DMRT) (95% confidence) confirmed statistically significant seasonal variation in these physicochemical indicators. Further, Varimax-rotated factor analysis and cluster analysis identified clear seasonal shifts, linking fluctuations primarily to rainfall, landslides, and human activities. Seasonal trends showed peak concentrations during winter followed by monsoon, summer, and post monsoon. Water Quality Index (WQI) assessments indicated the monsoon season exhibited the poorest water quality, driven largely by sewage inflow, agricultural runoff, and soil erosion, with subsequent declines in winter, post monsoon, and summer.
