Microplastic Pollution in Remote Freshwater Systems: Insights from Lakes and Reservoirs in Argentina and the United States

Abstract

Plastic pollution and its effects on freshwater ecosystem function are of growing concern, with recent studies showing that even remote environments are not immune to contamination. This study investigates the presence and characteristics of microplastics (MP) in eleven, remote lakes from the Patagonia region of Argentina (AR) and six lakes from Northern California, United States (US). Detected at all sites, microplastics (> 80 μm) concentrations ranged from 0.3 to 49 particles m−3 with a mean concentration of 5.4 ± 13.1 particles m−3. While lakes in the US had statistically nonsignificant but higher plastic concentrations compared to AR lakes, they did exhibit large variability (13.9 ± 20.5 versus 0.8 ± 0.4 particles m−3, respectively). Fibers dominated (71%), followed by fragments (23%) and films, with particles < 1 mm being predominant, indicating significant fragmentation in these remote freshwater environments. A total of 12 polymer types were identified, with polyester (PES) and polyethylene terephthalate (PET) comprising around 70% of the total, primarily in fiber form. No correlation was found between MP concentrations and watershed variables, proximity to urban areas, public access, or altitude. The widespread presence of synthetic fibers (PES and PET) and the absence of primary microplastics across lakes, regardless of their morphology or accessibility, suggest that anthropogenic activities and large-scale transport processes, such as watershed connectivity and atmospheric deposition, are key contributors to microplastic pollution for remote environments. These findings underscore the widespread impact of MP and emphasize the need for mitigation strategies at local, regional, and global scales to reduce plastic pollution effectively.

Keywords: plastic litter, dam, subalpine, watershed