GIS based accumulation model of microplastics loading in the Saint John River watershed

Abstract

As microplastic pollution in freshwaters becomes a greater area of focus for many researchers, the development of GIS based mapping tools specific to this field becomes increasingly important. Although many GIS models have been constructed to map the transport and sedimentation of various types of particulates through river systems, models specific to microplastics have yet to be developed. The goal of this study was to create a GIS based accumulation model of microplastics loading in the Saint John River watershed. This model considers the location of potential microplastic point sources such as wastewater treatment plants and tributaries, as well as the rivers flow strength and direction. Observed suspected microplastic concentrations from the Kennebecasis and Naskwaak tributaries were used to calibrate and test the accuracy of the model’s predictions. Waste water treatment plants seem to be better predictors of suspected microplastic concentrations than tributary confluences. The outcome of this project will further the understanding of microplastics pollution in the Saint John River watershed, and will serve as a reference to implement similar models in other freshwater systems.