Plastic debris in lakes and reservoirs

Plastic debris is thought to be widespread in freshwater ecosystems globally(1). However, a lack of comprehensive and comparable data makes rigorous assessment of its distribution challenging(2,3). Here we present a standardized cross-national survey that assesses the abundance and type of plastic debris (>250 mu m) in freshwater ecosystems. We sample surface waters of 38 lakes and reservoirs, distributed across gradients of geographical position and limnological attributes, with the aim to identify factors associated with an increased observation of plastics. We find plastic debris in all studied lakes and reservoirs, suggesting that these ecosystems play a key role in the plastic-pollution cycle. Our results indicate that two types of lakes are particularly vulnerable to plastic contamination: lakes and reservoirs in densely populated and urbanized areas and large lakes and reservoirs with elevated deposition areas, long water-retention times and high levels of anthropogenic influence. Plastic concentrations vary widely among lakes; in the most polluted, concentrations reach or even exceed those reported in the subtropical oceanic gyres, marine areas collecting large amounts of debris(4). Our findings highlight the importance of including lakes and reservoirs when addressing plastic pollution, in the context of pollution management and for the continued provision of lake ecosystem services. This manuscript benefited from conversations at meetings of the Global Lake Ecological Observatory Network (GLEON; supported by funding from US NSF grants 1137327 and 1702991). This work was supported by the University of Milano-Bicocca (UNIMIB). Raman facilities were provided by the Department of Earth and Environmental Sciences (DISAT, UNIMIB) and the Interdepartmental Network of Spectroscopy (UNIMIB). We gratefully acknowledge G. Candian and E. Caprini for their assistance in the laboratory activities and data analysis. A.M.A.-G. acknowledges the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2020). R. Bao acknowledges support from Project IMPACOM (PID2019-107424RB-I00) of the Spanish Ministry of Science and Innovation. M.C.-A. was supported by a Ramon y Cajal contract financed by the Spanish Ministry of Science and Innovation (RYC2020-029829-I). M.C. acknowledges support from Cátedra EMALCSA-UDC (industrial chair). R.C. was sup