Specialists from the Ural Branch of the Russian Academy of Sciences developed a method for assessing urban microplastic pollution and tested it in Yekaterinburg. Samples were taken in the VtuZgorodok residential area – at six sites near Kovalevskaya, Komsomolskaya, and Akademicheskaya streets. The obtained average values were then extrapolated to the entire residential area of the city, covering 128 km².
Mass fraction of polyethylene in the floating fraction smaller than 100 µm by sampling points:
- Kovalevskaya St., 20 — 6.37%;
- Kovalevskaya St., 16 — 5.54%;
- Komsomolskaya St., 34 — 7.13%;
- Komsomolskaya St., 31 — 14.28%;
- Komsomolskaya St., 19 — 9.26%;
- Akademicheskaya St., 23b — 5.85%.
The most accurate method was found to be a combination of infrared Fourier spectroscopy and elemental CHN analysis: polyethylene is unmistakably identified by the ratio of carbon and hydrogen in the particles. Manual selection with visual analysis and Raman spectroscopy proved ineffective – out of 240 particles, only one PET fiber could be correctly identified.
The obtained 352 tons is a minimum estimate, emphasized the project leader, senior researcher at the Institute of Industrial Ecology, Ural Branch of the Russian Academy of Sciences, Andrian Seleznev. Large fragments ranging from 3 to 5 mm, particles larger than 100 µm, microplastics in the mineral matrix, and other polymers besides polyethylene were not taken into account.
The method could be the first step towards an environmental monitoring system and the development of standards for permissible microplastic content in urban environments. The research results, supported by a grant from the RNF and the Sverdlovsk Oblast government, were published in the journal Geography, Environment, Sustainability. The estimate of 352 tons represents about 1100 mg of microplastics per kilogram of street deposits, and the actual volume of pollution may be higher.