Vertical water column position determines density and types of microplastics in Harvey’s Lake, the largest natural lake by volume in Pennsylvania

Abstract In deep stratified lakes, knowing the mechanisms determining the vertical distribution of microplastics (MPs) is necessary to understand their total influence on aquatic food webs fully. The authors of this article collected MPs at seven depths in the water column using a Schindler–Patalas plankton trap and from the bottom lake sediments using a Ponar Grab Sampler. The type and number of MPs varied by depth. MPs were mostly large fibers in the surface water (1 m) or nonfiber particles in the bottom sediment (30 m), likely due to temperature-associated density differences and other natural lake processes. These findings support the conclusion that vertical distribution is important when MP pollution in deep stratified lakes is considered. Notably, most MPs (65%) were attached to algae, which could have implications for higher trophic levels and key ecosystem processes.