Microplastics in Baltic bottom sediments: Quantification procedures and first results

Microplastics in the marine environment are known as a global ecological problem but there are still no standardized analysis procedures for their quantification. The first breakthrough in this direction was the NOAA Laboratory Methods for quantifying synthetic particles in water and sediments, but fibers numbers have been found to be underestimated with this approach. We propose modifications for these methods that will allow us to analyze microplastics in bottom sediments, including small fibers. Addition of an internal standard to sediment samples and occasional empty runs are advised for analysis quality control. The microplastics extraction efficiency using the proposed modifications is 92±7%. Distribution of microplastics in bottom sediments of the Russian part of the Baltic Sea is presented. Microplastic particles were found in all of the samples with an average concentration of 34±10 items/kg DW and have the same order of magnitude as neighbor studies reported.