To minimize contamination all apparatus used were either glass or stainless steel and was washed with ultrapure water (Advantec® RFU685DA). Latex or nitrile gloves were worn for all procedures and a 100% cotton lab coat was used. All steps were carried out on a sanitized clean bench with positive air flow for both sediment and surface water respectively. When not in use the filtration apparatus was covered in aluminium foil. Procedural blanks were taken by leaving an uncovered paper filter while processing samples, no contamination was found. For blank nets collected during surface water sampling, less than 5 particles were found in some while none in others.