It turns out that the tributaries of the Neva river in the eastern part of the city are the dirtiest. Furthermore, the samples of bottom deposits from the Okkervil river "suggest an ecological disaster".
A group of students in geoecology from St. Petersburg Mining University have completed their fieldwork as part of an academic internship. Over a fortnight, the youngsters, guided by their teachers, had been collecting samples of soil, air, water, and sediment at various locations. Studying the samples' chemical composition is next on the agenda, but preliminary monitoring results are already available.
For instance, measurements of noise levels near the Komarovsky bridge – built over the Okhta river – reveal that the acoustic impact has exceeded the threshold limit values. It comes as a result of the high traffic load during the morning rush hour. As for soil, it is yet unclear whether it meets the threshold criteria, with the findings coming in upon completing the laboratory studies. Mining University's researchers, however, believe there is no indication that this year's data will significantly differ from that of previous years.
"We usually take samples in recreational areas — in parks and on the banks of rivers. When examining their chemical composition, it is rare to record the exceedance of the maximum permissible concentrations of pollutants. There is a logic: every spring, the topsoil in most of such locations changes to the new one. In contrast, samples taken near main roads or petrol stations often exhibit an excess of threshold values — say, in nitrogen oxide. I would not call this a widespread phenomenon, though," says Aleksandr Danilov, senior researcher in the Department of Geoecology at Mining University.
On the other hand, when it comes to anthropogenic impacts on stream ecosystems, there are few reasons to be optimistic. Whilst in Leningrad Oblast, one square metre of sediment in rivers can serve as home to hundred species of fauna – molluscs, arthropods, other marine creatures, only a handful survive in the rivers of the city. Most of them are incredibly hardy species.
Denis Petrov is an associate professor at the first higher technical university in Russia, working alongside Aleksandr Danilov at the Department of Geoecology. He notes that the Okhta river and its tributaries - the Lubya and Okkervil – are the most illustrative example of anthropogenic effects. Those waterways are the city's most polluted; therefore, in 2021, they were chosen as training locations for the students.
"It is clear that building large residential compounds upon watersheds – as was done in Murino and Kudrovo, Leningrad Oblast – seriously affects water quality. The samples taken at the mouth of the Okhta indicate that the values for iron, manganese, copper, and aluminium are tens of times higher than the limit values. At almost all sampling sites, we have detected high concentrations of suspended solids and ammonia nitrogen. Sediment accumulates toxicants too. Moreover, their concentrations exceed those seen in the water tenfold or even a hundredfold. Oligochaetes are the dominating species in most samples, which is evidence of low oxygen levels and water contamination by municipal sewage. Some specimens, such as from the mouth of the Okkervil, lack zoobenthos altogether, which suggests an ecological disaster," emphasises Denis Petrov.
Nonetheless, he adds that collecting data on the environmental health of St. Petersburg is not the primary purpose of the training sessions. It is more important to engage youth in science. Considering the upcoming law, initiated by Vladimir Putin, obliging organisations' owners to remediate the cumulative environmental damage, the task mentioned above is of particular significance. After all, specialists in the field of ecology will become much more demanded.
"This format of training activities has proven itself as optimal for students in ecology:
- They gain skills in sampling and conducting primary analysis of the environmental situation.
- They develop an interest in scientific work, and the results they have obtained in practice form the basis for further research.
- During fieldwork, young people can see for themselves the condition of the city's water bodies and fully realise the importance of the profession they have chosen," explains Denis Petrov.
