Occurrence and distribution of microplastics in marine sediments along the Belgian coast

► Microplastic concentrations were studied in Belgian marine sediments. ► Different areas (beaches, harbours and open sea) were compared. ► Harbours exhibited the highest microplastic concentrations. ► Highest concentrations were 15-50 times higher than those found in other areas. ► Analysis of sediment cores suggest increasing microplastic concentrations.