Detection of microplastics particles in the aquatic environment by staining

Abstract

Introduction. Microplastics are among the most common environmental contaminants worldwide, which levels of pollution and harm to health have begun to be assessed only recently. Biological activity of microplastics has been established in "in vivo" and "in vitro": studies: they were found to impair the development and functioning of the digestive, reproductive, central nervous, immune, and circulatory systems, induce tissue and organ dysplasia, be geno-, neuro-, and cytotoxic. The findings necessitate monitoring of microplastics in water by supervisory authorities and business entities. Yet, there is no official method for determining microplastics in the aqueous environment in the Russian Federation. Our objective was to apply an express method for the qualitative determination of microplastics in surface waters and treated water before supply. Materials and methods. We analyzed water samples taken from two regional reservoirs and at water treatment plants before supply to the centralized system in two industrial cities of the Sverdlovsk Region by Nile red staining and subsequent identification of microplastics using a phase-contrast fluorescence microscope. Results. We found microplastics in both surface and treated water samples, and established their shape and size. Limitations. This method evaluates only qualitative characteristics of microplastics without establishing their chemical composition; the resolution of a microscope determines analytical accuracy. Conclusions. The applied method has enabled us to find microplastics in surface waters sampled at different depths and in the treated water before supply. Round and rod-shaped particles were observed in both types of water while those in the form of elongated filaments were detected only in surface water samples.