The Oder River has the natural ability to self-purify (as any river does), that is, to convert pollutants into simple compounds that are harmless to the ecosystem. The process works well and the ecosystem defends itself, as long as humans don’t degrade it too much. The golden algae bloom in the Oder River is the result of many factors, and the constant flow of sewage is one of them. An experiment conducted by scientists to try to get rid of golden algae in the Gliwice Canal, known as the “Gliwice Canal”. artificial water body, has proven effective. But is it for long?
Oder – what was the experiment about?
Toxic blooms of Prymnesum parvum, so-called. golden algae, are causing massive fish die-offs in many parts of the world and contributing to large-scale degradation of ecosystems. Therefore, ways to combat this invasive species are still being sought. We have written about the start of the experiment on the Gliwice Canal in previous issues of Water Matters. At the time, we pointed out that the condition for the occurrence of golden algae is the availability of suitable habitat, i.e. waters of a certain salinity. In contrast, the issues of other determinants – including nutrients, temperature, hydrological conditions, light – are not clear and still need to be studied.
At the end of June this year, commissioned by the Ministry of Climate and Environment, the following was produced: Report on the performance of experiments on the neutralization of golden algae in the locks of the Gliwice Canal . As it reads, the project’s countermeasures against golden algae were carried out by a multidisciplinary team of experts and scientists. Since this spring, three experiments have taken place on the Gliwice Canal using different agents to control toxic Prymnesum parvum blooms. It should be noted that the Gliwice Canal is the so-called. An artificial body of water, that is, created by human activity and does not resemble a natural river ecosystem.
Built in the 1930s. Last century, the canal has six navigable locks, making it possible to traverse more than 40 kilometers of its length. From the chronology of conducting the experiments indicated in the report, it appears that the first team of scientists began work in March of this year. A preparation of bentonite clay enriched with lanthanum was then used. This formulation is commonly used for the reclamation of lakes and reservoirs. Subsequently, an iron coagulant (ferric chloride formulation) was tested under both laboratory and field conditions. In contrast, the last experiment tested the effect of hydrogen peroxide (hydrogen peroxide water) on the abundance of golden algae.
Conclusions of the experiment
The use of the first of the preparations – lanthanum-enriched bentonite clay – over a period of one month of conducting the experiment, caused a relatively large reduction in the abundance of golden alga, i.e. Up to 20% of the initial state. It has been found that even better results can be obtained when the formulation is combined with disodium carbonate, but this requires additional studies. A side effect of this experiment was a reduction in phosphate by up to 50% and a mitigation of the effects on fish of toxins secreted by Prymnesum parvum.
The second experiment, based on ferric chloride, resulted in a significant reduction of algae under laboratory conditions. In the field, the results have not been as good. In addition, a number of limitations of this method have been identified, including. It can only be applied to standing water, possibly reservoirs with long retention times.
An experiment using hydrogen peroxide proved effective in inhibiting golden algae blooms. After the application of the product and rapid decomposition into oxygen and water, phytoplankton blooms were still present, but already with a small proportion of golden algae. The degradation of phytoplankton cells has released significant amounts of nutrients into the water, which have become food for other algae. Because of this, the use of this product should be approached with caution. The product can be used topically, in closed tanks or for cleaning equipment or vessels, so as not to cause transmission of golden algae.
The report concludes that the substances used in the experiments appear to be effective for inhibiting Prymnesium parvum blooms or even getting rid of it from the environment, especially immediately after application, but the use of the formulations in question is possible under strictly defined conditions, and carries a number of risks.
What’s next?
The experiments did not stop there. The report mentions that work is currently underway on another, based on the use of a barley bioinhibitor, which involves spreading out and submerging bags of barley straw. A separate report on this activity is to be produced.
Undoubtedly, further attempts should be made to neutralize golden algae. This invasive species has led to an ecological catastrophe in the Oder River and, scientists promise, it won’t stop there. It seems that we have created ideal conditions for him to develop.
Water management is not just ad hoc action when the situation is an emergency. It’s also about proper catchment management at all times and being ready for changing conditions – disappearing watercourses, droughts or floods. This will not be avoided. Failure to prioritize and organize activities in Polish catchments will lead to disasters similar to the one in the Oder River. At the moment, an official issuing a water permit, such as for a sewage discharge, has no tool to check the actual situation in a given basin, and it’s probably worthwhile for him to know if another permit isn’t the proverbial nail in the coffin for the river he’s supposed to protect.