Human pollution in Lake Balaton: no emergency, but the trend is worrying

In the framework of the "Honestly about Lake Balaton" professional meetings, a scientific lecture was held on 12 June 2024 in Tihany at the HUN-REN Balaton Limnological Research Institute. According to our current knowledge, there is no threat to human health at the moment, but the trends are a cause for concern," the organisers said in a summary statement. Researchers from the University of Pannonia also gave a presentation at the event (Source: hirbalaton.hu)

While the previous events of the "Honestly about Lake Balaton" series dealt with current - and already obvious - problems (water supply, water blooms, algal toxins, the situation of reed beds, climate change), this time the researchers focused attention on a problem that is no less topical, but still barely perceptible to the everyday person.

Lake Balaton has been and is still subject to a great deal of human interference that threatens its living systems and could jeopardise future human use of the lake. In this context, leading experts have analysed the pathways and quantities of man-made (micro)pollutants (e.g. pharmaceutical residues, contraceptive hormone derivatives, UV-filtering compounds, pesticides, microplastics) entering our surface waters, especially Lake Balaton.

What are the most common pollutants?

Can these compounds and agricultural chemicals enter lakes and drinking water and, if so, how do they affect wildlife, biodiversity and water quality?

The speakers at the event agreed that anthropogenic pollutants entering the lake are threatening the aquatic ecosystem, reducing biodiversity and may be contributing to changes in the functioning of Lake Balaton. On this basis, they make the following recommendations:

Decision-makers should take action to reduce the use of hazardous substances in the coastal zones of Lake Balaton through appropriate (controlled) regulations, for example by changing the method of weed control along the railway, by tightening the use of agricultural herbicides, fungicides and insecticides, and by making it practical to facilitate the collection of pesticide residues and their packaging that are surplus in small gardens and households;
residents of the municipalities around the lake, holidaymakers and tourists visiting Lake Balaton can do a lot to reduce the amount of hazardous substances they use and which are currently being released into the environment (e.g. pharmaceutical residues, UV-filtering compounds, pesticides, microplastics), to use them more (environmentally) consciously and to manage their waste more carefully; the value of coastal zone biota, reedbeds and other ecosystem services provided by biotic communities in the disposal of anthropogenic (micro)pollution in surface waters is incalculable and their sparing, maintenance and conservation are therefore of paramount importance.

Speakers highlighted the following points in their presentation:

Zsolt Pirger, deputy director of basic research and head of the research group of the HUN-REN Balaton Limnological Research Institute, explained in his presentation that the research institute started in 2013 to study invertebrate organisms in surface waters, in order to investigate anthropogenic pollution. Data on this topic were previously unavailable in Lake Balaton and its catchment area, but the institute has now succeeded in building up a large-scale analytical infrastructure that can routinely detect human pollution in surface waters of the Lake Balaton ecoregion and estimate environmental risk based on the concentrations.

Judit Sulyok, senior research fellow at the University of Pannonia "Tourists everywhere? - Tourism in the Lake Balaton region in the light of environmental impacts", she said that tourism contributes significantly to global emissions. In the case of destinations that rely on natural assets, including Lake Balaton, it is particularly important to protect the natural environment. Several developments related to sustainable tourism have taken place in the region in recent years. The current challenges for tourism mobility include the sustainable behaviour of visitors, the use of environmentally friendly modes of transport and the development of demand for local products. Future success will always require the involvement and active participation of a wide range of stakeholders in the development and implementation of solutions.

In her presentation, Éva Molnár, a research associate of the HUN-REN Balaton Limnological Research Institute, stressed that in addition to surface water, organic (micro)pollutants of human origin can also be detected in sediments and living organisms, biota. In their studies, they focus mainly on pharmaceutical residues, contraceptive hormones, chemical UV-filtering compounds in sunscreen cosmetics and, together with colleagues from the Hungarian University of Agricultural and Life Sciences in Gödöllő, on micro-pollutants. They will determine the spatial and temporal distribution, quantitative relationships, dynamics, seasonality and typical concentrations of these pollutants and, based on this information, estimate typical environmental risks. The potential physiological effects of medium and high risk pollutants will be tested on aquatic invertebrate model organisms. Their results will be communicated to the authorities and decision-makers managing Balaton.

Márta Vargha, senior expert at the National Centre for Public Health and Pharmacy, said that the biggest concern for the public in terms of drinking water quality is pharmaceutical residues and other organic micropollutants. X-ray contrast media, non-steroidal anti-inflammatory drugs and industrial pollutants were the most abundant contaminants in the Danube, but were also effectively removed by coastal filtration. Risk assessment calculations have shown that the health risk of organic micropollutants in drinking water is negligible. However, they can pose a risk to algae and fish in surface waters, so reducing emissions is a priority.

Zsolt Pirger, head of the Ecophysiological and Environmental Toxicology Research Group of the HUN-REN Balaton Limnological Research Institute, summarised the physiological effects of anthropogenic pollution in aquatic model organisms. He pointed out that these micropollutants disrupt the physiological processes of sensitive, otherwise untargeted organisms in the aquatic ecosystem, affecting the community as a whole and, in extreme cases, locally the biodiversity. After presenting the model organisms, he described in detail the experimental set-ups they use and the treatments they have carried out under laboratory conditions. Their work focuses on the behavioural patterns that change in response to treatments (e.g. locomotion, feeding, reproduction, learning) and the (neuronal) cellular changes that underlie them. Based on their findings, they have drawn attention to the fact that the future of our surface waters, specifically Lake Balaton, is in our hands. In order to preserve the biodiversity, good water quality and attractive tourism value of the lake, prevention and responsible citizenship are necessary.

István Szabó, Head of the Department of Microplastics as Microbiological Vectors at the Hungarian University of Agricultural and Life Sciences, said in his presentation that the use of plastics has significant environmental consequences. In addition to the harmful effects on animals and humans, micro- and nanomaterials that are released into our surface waters can also be important as carriers and habitats in living waters. They can bind hazardous chemicals on their surfaces, but they can also harbour specific biological communities, and plastic surfaces can be vectors for invasive species and even pathogenic micro-organisms. Monitoring these indirect environmental risks is a complex task but essential to understanding the vulnerability of surface and groundwater systems.

"Out with the pesticides! ", Gergő Tóth, a researcher at the Hungarian University of Agricultural and Life Sciences, reported that during six years of pesticide monitoring in the Balaton and its sub-basin area, 63 pesticide residues were detected in surface water and sediment samples, during which time herbicides dominated (~50%), followed by fungicides and insecticides/repellents in almost equal proportions. On average, 5-6 compounds were identified in the water samples, with a concentration range of 0.01-17.2 µg/L. There was a strong seasonal effect, with significant differences in both concentration and number of compounds in summer compared to spring and autumn. The predominant compounds in the samples were DEET (active substance in mosquito and tick repellent products), the herbicide terbuthylazine, the herbicide atrazine, which has been banned for almost two decades, and two degradation products, AMPA and deethyl-atrazine.

In her presentation "Glyphosate, or the effect of "necessary evil" on algae", Edina Lengyel, researcher at the University of Pannonia, said that glyphosate is known to have many harmful effects. Nevertheless, it is still the most widely used herbicide worldwide. Glyphosate-based herbicides are also used on the Balaton rail network, which runs along the shoreline of Lake Balaton throughout its entire area, so the chances of the herbicide entering the lake are high. Their research has shown that glyphosate at low concentrations results in hormesis, while at higher concentrations it negatively affects the physiological parameters of several algal species, which may even affect ecosystem function and functioning. Considering the economic and conservation importance of Lake Balaton, reconsideration of glyphosate use in the Balaton area is strongly recommended.

"Possibilities for mitigation and removal of organic micro-pollutant loads" was presented by Renáta Gerencsérné Berta, researcher at the University of Pannonia. She said that the proper water quality of Lake Balaton cannot be ensured in the long term only by monitoring activities. Therefore, it is necessary to start intervention on the main sources of pollution already identified in the region. Such potential points of investigation and intervention are wastewater treatment plants and industrial dischargers. At these points, the application of appropriate water treatment technology can reduce the discharge of pollutants. Another point of intervention is the abstraction and treatment technology used to supply drinking water to the public, which needs to be investigated and improved to reduce direct human exposure. It presented the latest and most important water treatment and purification technologies.

In his presentation entitled "Micro parts, macro solutions against micro pollutants in the Lake Balaton Region", Gábor Molnár, Director of the Balaton Development Council (BFT) Agency, said that the Balaton Development Council aims to ensure dialogue between different stakeholders, thus facilitating the timely identification of problems, the development of solutions and the coordinated implementation of measures. The BFT's role is to coordinate cooperation, facilitate dialogue between scientific results and decision-makers, and involve local communities in these processes. It is considered important to promote innovative solutions, disseminate local good practices, raise awareness and promote the effective use of available tools and resources.

Cover image illustration by Nikolett Emmert, pexels.com