Microplastic contamination in Patagonian lakes varies with sampling method but not with urbanization level

Abstract

The influence of sampling method on microplastic (MP) quantification and the impact of population density on the levels of MP contamination in surface waters from Patagonian lakes were investigated. Six lakes located in Northern Patagonia (Argentina) were studied using two different sampling protocols widely reported in the literature: water collected in glass bottles vs. water collected using a 50 µm mesh size net. To assess the influence of population density on MP contamination, urban lakes (Nahuel Huapi, Gutierrez and Moreno) and lakes with no urbanization on their shores (Espejo, Espejo Chico and Mascardi) were considered. We identified contamination with secondary MP at all the freshwater lakes studied, with predominance (> 90%) of textile-based microfibers (MF). Remarkably the levels of contamination were similar in all the sites, independently of population density, which supports the notion that there is atmospheric transport of MP between places. The greatest variability found was among sampling methods, with differences above of three orders magnitude. Samples collected directly in 1-liter bottles had an average of 5,257 MP/m3 in comparison to 1.57 MP/m3 in the samples that were collected with a 50 µm net. Results highlight the need to address mesh size when looking for textile microfibers and to develop standardized sampling protocols to make studies on freshwater MF contamination comparable.