The role of water management and its effect on microplastic transport and fate

River networks act as pathways for transporting microplastics (MPs) to the oceans and can serve as both intermediate and long-term sinks. Understanding MP stream concentrations and loads (concentration multiplied by discharge) is crucial for assessing their downstream transport and potential impacts on ecosystem health. Despite their importance, models often simplify river corridors as dendritic systems and studies on the influence of water management practices on MP transport are limited. Two systems were studied, one where we compared the spatial downstream evolution of MP concentrations and loads in Boulder Creek (BC) and its less urbanized tributary, South Boulder Creek (SBC), in Colorado, USA. In 2019, 21 water samples were collected to understand sources along the river corridors. A loading calculation method used for metals was applied to identify sources quantitatively across river segments. The degree of urbanization influenced MP patterns, as suspected, however, in both rivers water management practices diverted flow, and MPs were removed and redistributed within or between catchments I both rivers. The second study compared MP concentrations and loads 1000 m downstream of a wastewater treatment plant (WWTP) with a land cover of 74.6 Also see: https://micro2024.sciencesconf.org/559170/document