RECETOX Seminar Series: Barbara Kubíčková (RECETOX), Marcel Schneider (RECETOX), Regiane Sanches Natumi (EAWAG): Natural Toxins in the Freshwater Environment – Occurrence, Fate and Health Implications. (Online lecture)

Barbara Kubíčková (RECETOX), Marcel Schneider (RECETOX), Regiane Sanches Natumi (EAWAG)

Natural Toxins in the Freshwater Environment – Occurrence, Fate and Health Implications. (Online přednáška)

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Abstrakt:

Clean drinking water is crucial to human health and wellbeing. Global climate change leads to extended dry heat periods in summer and aggravates freshwater shortage - which may affect the supply of clean and safe drinking water. Especially surface water bodies, which are often used for drinking water extraction, are prone to contamination. While chemical pollutants and pharmaceuticals are already being targeted by environmental protection policies, natural toxins receive little attention in terms of environmental levels in freshwater, their health hazard and potential risk, as well as management strategies. Natural toxins are, amongst others, produced by terrestrial plants and aquatic cyanobacteria in large quantities – the latter being intensified due to poor wastewater treatment, nutrient emission from agricultural areas and global warming. The NaToxAq project (http://www.natoxaq.eu), consisting of experts on in silico predictive modelling, chemical analysis, toxicology and risk assessment, aims to improve the understanding of the sources, occurrence, fate and health impact of natural toxins in freshwater environments as well as the efficiency of their removal by water treatments. We aim to inform the water supply sector and policy makers on the risks of natural toxins and their management strategies to assure provision of safe drinking water for future generations.

Barbara Kubíčková (RECETOX): Effects of cyanobacterial metabolites on human neural differentiation

Cyanobacterial blooms produce and release several toxic metabolites to surrounding (fresh-) waters. Amongst these metabolites are compounds with retinoid-like activity, that have been linked to teratogenic effects in vitro and in vivo at environmental levels. To investigate effects on human neural development, I adopted a human neural stem cell model, that differentiates in vitro into a mixed culture of neurons and glia within 22 days. Biomarkers of neural differentiation are monitored using qPCR, western blot and immunocytochemistry throughout the differentiation. Besides effects of cyanobacterial metabolites, this model will be useful to investigate recent research priorities related to the increased record and/or incidence in neurodevelopmental diseases (e.g. AD(H)S, autism spectrum disorders, learning impairment etc.) and neurological disorders (e.g. Parkinson’s Disease, dementia, Alzheimer’s Disease, etc.).

Marcel Schneider (RECETOX): Degradation of cylindrospermopsin using advanced non-thermal plasma technologies 

Non-thermal plasmas (NTPs) have received much attention for their application in wastewater and air purification. Classified as Advanced Oxidation Processes, plasmas ignited in water or at the air-water interface efficiently generate a vast range of reactive species. Although plasmas have been shown to even degrade recalcitrant organic pollutants such as pharmaceuticals, available information for their application in drinking water treatment and cyanotoxin degradation is limited.

In the present research, six different plasma sources – corona, surface, spark, gliding arc and dielectric barrier discharges (DBD) and a plasma jet – were compared for their efficiency to degrade a cyanobacterial extract containing cylindrospermopsin. Two plasma types were then selected for further in-depth study of the efficiency and degradation mechanisms.

The spark discharge showed the most energy-efficient degradation, followed by the other sources showing similar efficiencies, while the plasma jet was least efficient. The follow-up detailed studies included the corona-like discharge and the DBD. For the corona-like plasma, the degradation efficiency increased with increasing voltage and solution pH. After 15 min of plasma treatment at pH ≥ 7.5 degradation even progressed without further plasma application. This pH-dependent effect was not observed in the DBD reactor, whose degradation efficiency increased with decreasing voltage. Degradation in the corona-like plasma is primarily promoted by hydroxyl radicals, whereas the DBD reactor mainly produces ozone and NOx.

The application of NTPs appears to be an innovative and promising approach for efficient removal of cyanotoxins such as cylindrospermopsin from drinking water.

Regiane Sanches Natumi (EAWAG): Production dynamics and degradation of understudied cyanopeptides

Cyanobacterial blooms are a growing public health concern due to the production of a wide range of bioactive compounds including hundreds of cyanopeptides beyond the famous hepatotoxic microcystins. Hardly any information is available regarding the occurrence, production dynamics, environmental fate and toxic mode of action for the majority of cyanopeptides. To improve our understanding of the exposure side of the risk equation for cyanobacterial bloom events I evaluated a) production dynamics of the potentially toxic cyanopeptides, and b) the photostability of understudied cyanopeptides in surface waters. By analyzing the production dynamics of bloom forming cyanobacteria, we demonstrate that these understudied cyanopeptides can be just as abundant or even dominating over the well-known microcystins and total production can be affected by change in nutrient availability. By investigating the phototransformation process of 39 tentatively identified cyanopeptides, we saw that 22 compounds registered detectable degradation, and from those only two cyanopeptides were show to degrade rather fast with a half-live of less than 5 hours. Furthermore, by investigating the role of pH in photochemical transformation, we saw that 14 cyanopeptides showed increased degradation with higher pH values (pH > 9). The knowledge gained through this project provides necessary information regarding co-occurrence and stability of emerging cyanopeptides for risk assessment of cyanobacterial blooms for recreational use and their potential relevance in drinking water treatment.

Acknowledgements

Many thanks to the NaToxAq consortium for contributing their research results and supporting investigations in the pioneer field of natural toxins in freshwater environments. This project received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 722493. The information and views set out in this presentation are those of the author and do not necessarily reflect the official opinion of partners of the NaToxAq project, the European Union’s Research Executive Agency or their subsidies.