[en] The occurrence of cyanobacteria in freshwaters attracts much attention due to its associated health threats and ecological implications. Yet data on the composition of cyanobacteria taxa and toxigenicity in some regions is still scarce. Here, we explored the occurrence of cyanobacteria and cyanotoxins in three locations in Ukraine (reservoir for Kasperivtsi Hydrothermal Power Plant and outflowing River Seret, and cooling pond of Khmelnytsky Atomic Power Plant) in summer 2017. Cyanobacteria were a dominant fraction at all stations. A number of potent-toxin producers were identified including Cylindrospermopsis raciborskii, Aphanizomenon gracile, Dolichospermum flos-aquae, and Planktothrix agardhii. Screening for the presence of dissolved and particulate content of microcystins (-LR, -YR, and -RR), cylindrospermopsin, and anatoxin-a yielded negative results. The studied waters displayed no toxicity in human platelets in vitro. Further toxicological and ecological studies are necessary to evaluate the potential presence of cyanotoxin producers in Ukraine.

[en] Copper mining generates large quantities of waste, tailings, and acid outflows causing long-term environmental impacts and potential threats to human health. Valea Şesei is the largest tailing impoundment in Romania, created by flooding the valley (known as Valea Şesei) of the Metalliferous Mountains (a division of the Apuseni Mountains) with copper mining waste. The present study (i) estimated the total volume of tailings in this area; (ii) screened the concentration of 65 elements (rare earth and platinum group elements, alkali metals and alkali earth metals, transition and post-transition metals and metalloids) and cyanide concentrations in wastewater samples collected from tailing impoundment; (iii) evaluated the toxicity of these water samples using five in vitro bioassays employing human cells isolated from healthy donors and a short-term (1 h) exposure model. The sampled waters were highly acidic (pH 2.1–4.9) and had high electrical conductivity (280–1561 mS cm⁻¹). No cyanides were detected in any sample. Water samples collected from the stream (AMD) inflowing to the tailing impoundment were characterized by the greatest concentrations of alkali metals, alkaline earth metals, transition and post-transition metals, metalloids, rare earth elements, and noble metal group. At other sites, the elemental concentrations were lower but remained high enough to pose a relevant risk. The greatest magnitude of in vitro toxic effects was induced by AMD. Observed alterations included redox imbalance in human neutrophils followed by lipid peroxidation and decreased cell survival, significant aggregation of red blood cells, and increased prothrombin time. The study highlights that Valea Şesei is a large sink for toxic elements, posing environmental and health risks, and requiring action to prevent further release of chemicals and to initiate restoration of the area.