In a pilot study, microlitter was sampled with a Ferry Box system on the commercial ferry (M/S Color Line Fantasy) between Oslo and Kiel. The system acquired samples in the Danish part of the Skagerrak and Kattegat. In total thirteen samples were collected from September 2019 to February 2020 using mesh sizes 100 and 500 µm. Eleven samples were successfully processed. The samples were subsequently processed and analysed for chemical composition using FTIR. Microplastic amounts found ranged from 0 to 1.85 fragments or fibers per m3 (average 0.71 per m3).

Microlitter was sampled with a module fitted on a Ferry Box system on the commercial ferry cruises (M/S Color Line Fantasy) between Oslo and Kiel. The system acquired samples in the Danish part of the Skagerrak and Kattegat. In total seven samples were collected from 23-10-2020 to 02-11-2020 using filters of mesh sizes of 300 and 500 µm. Particles were visually identified and analysed for chemical composition using FTIR. Particle concentrations ranged from 0.39 to 1.85 particles per m3 (average 0.91 per m3).

The main part of the dataset has been collected within the MOMO project (Monitoring and modelling of cohesive sediment transport and evaluation of the effects of dredging and dumping operations on the marine ecosystem) at four locations (MOW1, Blankenberge, WZ-buoy, MOW0, Ostend and Geul van de Walvisstaart buoy). A large part of the data is from the MOW1 station, situated about 3 km offshore the harbour of Zeebrugge. Shorter time series have been collected for the Environmental Impact Assessment of the Belwind offshore windfarm at two locations (Blighbank, Gootebank) and the MOZ4 project (Westdiep location). A central objective of the MOMO project is to collect long-term time series of Suspended Particulate Matter concentration, size and transport in the coastal turbidity maximum located in the Belgian Part of the North Sea. Data from two sensors are included in this dataset. First, from a LISST-100X instrument, which contains four parameters: the optical transmission, the median distribution of the sediment particle size (micrometers), the Sauter mean diameter (micrometer) and the total SPM volume concentration (microlitres/litre). Second from in-situ observation of water turbidity derived from an Optical Backscatter Sensor (OBS) together with a CTD sensor. The following parameters are included: water pressure, salinity, water temperature, turbidity and SPM mass concentration (mg/l). The OBS is calibrated in the laboratory using standard turbidity solutions, and in the field using SPMC determined through filtration of water samples. -Observations of 3-D flow velocity field measured with an Acoustic Doppler Velocimeter (ADV). -In-situ observations of particle size distribution and sediment concentration measured by a Workhorse LISST-100X instrument. Four parameters are measured by the sensor: the optical transmission, the median distribution of the sediment particle size (micrometers), the sauter mean diameter (micrometer) and the total sediment volume (microlitres/litre). -Current profiles measured with an Acoustic Doppler Profiler (ADP) sensor -3-D flow velocity field measured with an Acoustic Doppler Velocimeter (ADV)