Biologists and Ecologists Will Check the Impact of Biodegradable Bags on Soil

11:46, July 13, 2021

Scientists and students will conduct a two-year experiment

Biologists and ecologists at Ural Federal University will test whether biodegradable bags really decompose in the soil, and find out whether they are harmful to the environment. To do this, scientists and students of the university will conduct a two-year experiment together with the Nika-Petrotek company. The specialists will plant 100 seedlings of Siberian pine (cedar) each in Yekaterinburg (the Michurinskiy Residential Complex) and at the UrFU Biostation (the Sysert District). The trees were divided into four categories: seedlings in ordinary soil, as well as seedlings in polyethylene bags, biodegradable and paper. University students will take soil samples in the fall of 2021 and 2022 and in the spring of 2022 to assess the condition of plants, insects, microbial composition, and how decomposed the plastic is. The goal is to determine if the bags interfere with plant growth and the life of insects, worms and other soil inhabitants.

"We will take control soil samples of plants growing without the bags and samples of the other three options. We will compare the microbiological composition of these soils and based on the data we will be able to say whether microorganisms develop well in the root system area in the presence or absence of plastic, to conclude whether it is toxic," Irina Kiseleva, head of the experiment, director of the Center for Fundamental Biotechnology and Bioengineering at UrFU, explains the essence of the experiment.

If there are few microorganisms in the soil where trees are planted in biodegradable plastic bags, it will mean that they are killed by toxicants. If there are as few or more microorganisms than in the control version, it will mean that it is attractive to bacteria, bugs, other insects, and they can degrade it, break it down.

"For several years now, a scientific consortium in our country has been researching and developing the technology for biodegradable polymers at a serious level. Lomonosov Moscow State University, A. V. Topchiyev Institute of Petrochemical Synthesis of RAS, I. Ya. Postovsky Institute of Organic Synthesis of UB RAS and research and production company Nika-Petrotek received the first samples of plastic bags, disposable tableware and packaging materials, which decompose into water and carbon dioxide within three months to two years, depending on the ground where they are thrown away. The technologies being developed for the synthesis of biodegradable polymers are on the list of technologies recognized as advanced technologies for special investment contracts approved by the Russian government on November 28, 2020, No. 3143-r and have been tested for compliance with state standards. The time has come for full-scale tests on Ural soils, for which we turned to UrFU," commented Konstantin Lukyashin, technical expert at Nika-Petrotek.

According to scientists, truly biodegradable plastic should not disintegrate into small fragments (microplastic), but split into simple molecules.

"Pseudo-biodegradable plastic is not recycled in nature in any way. It breaks down into particles, but in terms of chemistry it remains the same polymer. The particles penetrate living organisms and cause negative consequences. This is why the problem of microplastics in the world's oceans is acute today. A truly biodegradable polymer is a complex molecule made up of many identical molecules. This complex molecule has to be broken down into simple ones that can be digested or eaten, for example by microbes. And our goal is to test whether biodegradable plastic really breaks down and does not harm the environment," says Irina Kiseleva.