The Canadian Case Study
(University of Windsor and Trent University). Dr Jill Crossman
Over 3000 samples have been taken in agricultural soils and runoff, adjacent river channels and bed sediments, stormwater drainage, wastewater treatment plant effluent, and biosolids sludge. Samples were taken before, during and after the application of biosolids to soils, with higher frequency sampling conducted during heavy rainfall events. A control site was also monitored where no biosolids were applied. Multiple samples were taken at each location to ensure the distribution of microplastics within the environment was characterized. Close collaboration with IMDEA ensured consistent sampling techniques (mesh sizes, sampling depths, etc.) between case studies.
Samples of sewage effluent at three different wastewater treatment plants are also being taken. Liquid and solid effluent are sampled at each treatment stage, in addition to the end biosolids product, to identify the pathway of microplastics through treatment plants. The aim is to identify the efficiency of treatment plants in removing microplastics from wastewater.
Samples are consolidated in our laboratory at Windsor, and a sub sample sent to NIVA for analysis of microplastics content using FTIR. Consolidation involves weighing, drying, and carefully combining samples taken from the same site on the same day (e.g. multiple soil samples taken across the same field during the same rainfall event are combined into a single core, representative of the average conditions across the site on that day).
Using Raman spectroscopy at the University of Windsor, we are also analyzing the variability in microplastics content between individual samples prior to consolidation, and between different stages of wastewater treatment. In partnership with NIVA, we are comparing MP results between analyses performed using FTIR and Raman methods.
A model of microplastics (INCA MP) has been applied to the Beaver and Orillia sites. Calibration will be performed in partnership with SLU using results from the field activities.