Occurrence and spatial distribution of microplastics in the surface waters of the Baltic Sea and the Gulf of Riga

The study is comparing microplastic debris distribution and composition in the Gulf of Riga and the Eastern Gotland Basin, Baltic Sea. Samples from 44 stations were collected from coastal and open water sites using Manta trawl (mesh size 300 mu m). The natural organic material was digested sequentially with sodium hydroxide, hydrogen peroxide and enzymes. Thereafter, micro-debris (16,315 particles) was identified by visual analysis and 5285 particles were analyzed with Attenuated Total Reflection Fourier Transform Infrared spectroscopy method. The abundance of particles varied from 0.09 to 4.43 particles per m-3. The fibers accounted for 66.1% of all encountered particles while the fragments for 30.2%. The predominant polymer types were polyethylene (77.9%) and polypropylene (11.1%). The relative proportion among polymer types varied considerably from station to station. The encountered concentrations of micro-debris were well in range of values reported from other regions of the Baltic Sea.

Automated summary

This study compared the distribution and composition of microplastic debris in the Gulf of Riga and the Eastern Gotland Basin in the Baltic Sea. The researchers found that the abundance of microplastic particles varied among different stations, with fibers and fragments being the predominant types, and polyethylene and polypropylene being the main polymer types encountered. The concentrations of micro-debris observed fell within the reported range of values from other regions in the Baltic Sea.