Distribution and characterization of microplastics in marine sediments from the Montenegrin coast

Plastic pollution in the world has led to an abundance of microplastics (MPs) and has been identified as a potential factor that can lead to serious environmental problems, especially in oceans and seas. Information on the current status of MPs pollution along the Montenegrin coast is insufficiently investigated. This study monitors the abundance, distribution, and sources of MPs, and identifies present polymers in the surface sediment of the Montenegrin coast, as well as comparison with previous research.

Ten sampling sites along the Montenegrin coast were selected to collect surface sediment samples. The upper layer of sediment (0-5 cm) was collected by a Petite ponar grab. The samples were dried, and density separation was performed using a NaCl solution. The abundance and morphological characteristics of MPs were determined using an optical microscope (DP-Soft software), while FT-IR analysis was done to identify the polymer type.

Microplastics were identified in all sediment samples with an average abundance of 307 ± 133 (SD) MPs/kg in dry sediment. The highest abundance of MPs was found in locations in the vicinity of highly populated areas, near wastewater discharges, and areas with high fishing and tourist activities. The most dominant shape types of MPs in all samples were filaments and fragments. The most common colors of MPs were blue and red, while the dominant MPs sizes were 0.1-0.5 mm and 0.5-1.0 mm. Of the eight identified polymers, PP, PE, and PET were the most common.

This study reveals MPs characteristics (abundance, distribution, shape type, colors, size, polymers type) in surface sediment along the Montenegrin coast, as well as the most significant sources of MPs pollution, and provides important data for further research on MPs to identify the effects of MPs pollution on the quality, health, and functionality of the marine environment.