Prevailing wind patterns influence the distribution of plastics in small urban lakes

Abstract

Cities generate large amounts of plastic waste and thus are often major sources of plastic pollution. Microplastics (particles < 5 mm) are a growing ecological concern as they are readily transported through the environment by wind, flowing water, and other transport processes. Here, we report the findings of an intensive field study that tested associations between prevailing winds and the distribution of plastic pollution around urban lakes (n = 20 lakes) in offshore sediments, shoreline sediments, and surface waters. We tested and found support for the hypothesis that prevailing winds influence the distribution of plastics around lakes. Overall, lakes had greater proportions of macroplastics (i.e., large plastic trash) and microplastics in sediments collected along northern lake shorelines. Notably, we found that macroplastic trash and total microplastics were, respectively, 1.7 and 3 times more abundant in sediments sampled along northern shorelines. Contrary to our expectation, we also found that microplastics in offshore sediments were in greater proportions along western lake shorelines, indicating that wind-driven processes might not explain the distribution of plastics in all lake zones. Furthermore, we observed no discernable patterns within lake surface waters and only captured a handful of suspended microplastic fragments and films from the water column. Overall, our findings revealed that the heterogeneous accumulation of plastic pollution at a lake is influenced, in part, by wind-driven processes. Moreover, these patterns extend across a network of lakes that were distributed across an urbanized landscape.