Onderzoeksrapporten

As a follow-up of a pilot study, an additional method development project was performed, aimed at improving the cleaning of sediment samples regarding natural organic and calcium-containing materials. Because the budget and time for this project was limited, this study was focussed on the most organic-rich sample Dutch sediment location, Voorland 1 (in the Westerschelde estuary). We tested several methods for digestion of organic matter, and finally selected a two-stage digestion using KOH and NaOCl, respectively. The resulting digestion method appeared to be promising, and will be tested in a NIVA-RWS method development project in 2025.

The microplastic identification software and its used settings have a substantial influence on the identification results. Therefore, a comparative and optimization study was performed using two software packages (siMPle and Purency), several siMPle versions and pipelines, and various polymer TV settings.

In this pilot project, we explored several method options for the monitoring of microplastics in marine sediments. This project was performed by the NIVA microplastic laboratory in Oslo, Norway, for the first time. Several method options (from NIVA and a modified Cefas method) were compared. Results indicate that additional cleanup of samples is needed, in particular of calcium-containing particles like foraminifera shells.