Global patterns and predictors of microplastic occurrence and abundance in lentic systems

Abstract

The majority of microplastic research has focused on seawater, with fewer than 4% of microplasticsrelated studies occurring on freshwaters. The limited available information suggests that theabundance of microplastics in freshwaters is often as high or even higher than marine environments.However, comprehensive investigations on occurrence and fate of microplastics in freshwaters arescarce and highly fragmented, partly because detection and identification of microplastic particles israther complex. In addition, up to now, harmonized and standardized protocols for the sampling andanalysis of microplastics in freshwaters do not exist, and studies with different research aims andhypotheses often report unstandardized results, making comparison among studies difficult. In thepresent study, we performed the first global standardized sampling and analysis effort to investigatethe occurrence and distribution of microplastics in surface water of lakes and reservoirs with differentanthropogenic impacts. Participants aim to collect water samples of freshwater systems with differentfeatures (e.g., area, depth, thermal behavior, watershed), following a common protocol. This establishes the collection of samples by horizontal trawling of a plankton net and, after treatmentwith hydrogen peroxide, the polymer identification through micro-Raman spectroscopy. This GLEONproject will allow obtaining comparable data about microplastic contamination in different freshwatersystems around the globe. With this global dataset, our goals are to determine whether a relationshipexists between the abundance of microplastics and the waterbody/watershed attributes andunderstand which factors are likely to influence the occurrence of microplastics in surface water oflentic systems.