Physical properties of aggregates exposed to varying concentrations of microfibres

Size, volume and settling velocity were measured by making a recording of the rotating tanks using a commercial digital single-lens reflex camera (Canon) equipped with a standard lens of 50 mm for focal length.
Settling velocity is measured in m d -1 . POC was measured with an elemental anlayzer isotope ratio mass spectrometry (EA-IRMS, ANCA-SL 20-20, Sercon Ltd. Crewe, UK). POC is measured in µg. Potential export flux was estimated for each treatment as an average of the final three timepoints (118h,143h and 163h) of the experimental period. This was done each treatment by using the POC-to-volume ratio to determine the POC content per aggregate and multiplying with the measured settling velocity to get potential POC flux from each aggregate.