FUNCTIONAL STATE OF THE MARINE MICROALGAE CULTURES AS AN INDICATOR OF THE WATER POLLUTION LEVEL OF THE SEVASTOPOL BAY

The possibility of using cultures of Black Sea planktonic microalgae of different taxonomic affiliation to assess the quality of the aquatic environment based on the assessment of their functional state is shown. The research was carried out on the diatom Phaeodactylum tricornutum, three dinoflagellates species Prorocentrum cordatum, Prorocentrum pusillum and Gyrodinium fissum, as well as the coccolithopho-ride Emiliania huxleyi. It was found that the waters of the Sevastopol Bay in the period from May to August 2021 in 50% of cases had a weak inhibitory effect on the growth of the tested species. In other cases, algae growth was either stimulated or the effect of pollution on cultures was not revealed. The need for using several types of algae in carrying out complex work on water biotesting of the coastal are-as of the Black Sea is highlighted.

Phosphorus uptake by Oscillatoria sp. microalgae for bioavailability under anaerobic condition to predict eutrophication

Phosphorus is generally considered the limiting nutrient for algae growth in the aquatic environment. The phosphorus uptake for algae can give information for bioavailability-P. The contribution of phosphorous to bioavailability was evaluated using uptake-P in water solution under anaerobic conditions. The more is the incubation time, the more is the phosphate bioavailability. The maximum bioavailability occurred at 14 days with a phosphate concentration of 50 ppm resulting in P-available of 18.41 ppm. There was a linear correlation between P-available with P-medium with R2 = 0.97. The phosphorus bioavailability can be resulted from the equation: [P-Available] = 0.3789 x [P-medium]. The phosphate absorbed by the algae Oscillatoria sp in anaerobic conditions with initial concentrations of 10, 20, 30, 40 and 50 ppm was 5.46, 8.65, 11.63, 17.99 and 18.41 ppm, respectively. The maximum efficiency adsorption occurred in the concentration of 30 ppm with 49.18% adsorption.

Assessment of SnO2 Nanoparticles’ Impact on local Pichoclorum Atomus Growth Performance, Cell Morphology and Metabolites Content

Oxide nanoparticles are among the most used nanomaterials and have received considerable attention over their potential ecological effects. Increasing investigations report toxicity of certain oxide nanoparticles, however, there are also studies showing opposite results, highlighting the fact that these nanoparticles may differ in their toxicological effects, which depend on particle variety and size, test organism species, and test method. The current study investigates the ecotoxicity of SnO2 nanoparticles on a local marine algae isolate. Five different concentrations (1, 5, 25, 50 and 100mg/L) were tested and the culture was followed for 72h. Algae growth, morphology and metabolites were followed each 24h. The obtained data showed that the SnO2 presented a toxicity on the algae growth that was decreasing with the dose, with lower doses presenting more negative impacts than the higher doses. In parallel, the slow growth observed at 1-5 mg/L was explained by the dramatic damages caused by the SnO2 on the cell morphology, which was detected using the scanning electronic microscopy. Indeed, this low negative impact of higher concentrations of SnO2 (50-100mg/L) is explained by the high agglomeration of ten particles leading to reduced effect on the cell morphology and health. Furthermore, and in accordance with the morphological data, the metabolites analysis data revealed that SnO2 nanoparticles induced stress, which was manifested by an increase in the lipid content and decrease in the proteins, a metabolite that is involved in the algal growth.

Accelerated Weathering Increases the Release of Toxic Leachates from Microplastic Particles as Demonstrated through Altered Toxicity to the Green Algae Raphidocelis subcapitata

Studies that evaluate the impact of microplastic particles (MPs) often apply particles of pristine material. However, MPs are affected by various abiotic and biotic processes in the environment that possibly modify their physical and chemical characteristics, which might then result in their altered toxic effect. This study evaluated the consequence of weathering on the release of toxic leachates from microplastics. MPs derived from six marine antifouling paints, end-of-life tires, and unplasticised PVC were exposed to UV-C radiation to simulate weathering. Non-weathered and weathered MPs were leached in algae growth medium for 72 h to demonstrate additive release under freshwater conditions. The model organism, green algae Raphidocelis subcapitata, was exposed to the resulting leachates of both non-weathered and weathered MPs. The results of the growth inhibition tests showed that the leachates of weathered microparticles were more toxic than of the non-weathered material, which was reflected in their lower median effect concentration (EC50) values. Chemical analysis of the leachates revealed that the concentration of heavy metals was several times higher in the leachates of the weathered MPs compared to the non-weathered ones, which likely contributed to the increased toxicity. Our findings suggest including weathered microplastic particles in exposure studies due to their probably differing impact on biota from MPs of pristine materials.

The Potential Risk of Electronic Waste Disposal into Aquatic Media: The Case of Personal Computer Motherboards

Considering that electronic wastes (e-wastes) have been recently recognized as a potent environmental and human threat, the present study aimed to assess the potential risk of personal computer motherboards (PCMBs) leaching into aquatic media, following a real-life scenario. Specifically, PCMBs were submerged for 30 days in both distilled water (DW) and artificial seawater (ASW). Afterwards, PCMBs leachates were chemically characterized (i.e., total organic carbon, ions, and trace elements) and finally used (a) for culturing freshwater (Chlorococcum sp. and Scenedesmus rubescens) and saltwater (Dunaliella tertiolecta and Tisochrysis lutea) microalgae for 10 days (240 h), (b) as the exposure medium for mussel Mytilus galloprovincialis (96 h exposure), and (c) for performing the Cytokinesis Block Micronucleus (CBMN) assay in human lymphocytes cultures. According to the results, PCMBs could mediate both fresh- and marine algae growth rates over time, thus enhancing the cytotoxic, oxidative, and genotoxic effects in the hemocytes of mussels (in terms of lysosomal membrane impairment, lipid peroxidation, and NO content and micronuclei formation, respectively), as well as human lymphocytes (in terms of MN formation and CBPI values, respectively). The current findings clearly revealed that PCMBs leaching into the aquatic media could pose detrimental effects on both aquatic organisms and human cells.

Characteristics of the Exchange Flow of the Bay of Quinte and Its Sheltered Embayments with Lake Ontario

The nature of the exchange flow between the Bay of Quinte and Lake Ontario has been studied to illustrate the effects of the seasonal onset of stratification on the flushing and transport of material within the bay. Flushing is an important physical process in bays used as drinking water sources because it affects phosphorous loads and water quality. A 2-d analytical model and a 3-dimensional numerical coastal model (FVCOM) were used together with in situ observations of temperature and water speed to illustrate the two-layer nature of the late summer exchange flow between the Bay of Quinte and Lake Ontario. Observations and model simulations were performed for spring and summer of 2018 and showed a cool wedge of bottom water in late summer extending from Lake Ontario and moving into Hay Bay at approximately 3 cm/s. Observed and modelled water speeds were used to calculate monthly averaged fluxes out of the Bay of Quinte. After the thermocline developed, Lake Ontario water backflowed into the Bay of Quinte at a rate approximately equal to the surface outflow decreasing the flushing rate. Over approximately 18.5 days of July 2018, the winds were insufficiently strong to break down the stratification, indicating that deeper waters of the bay are not well mixed. Particle tracking was used to illustrate how Hay Bay provides a habitat for algae growth within the bay.