Macroplastic pollution in riparian corridors of urban and pristine mountain streams in Patagonia (Argentina)

Abstract

Plastic pollution has garnered much more attention in marine environments, while scientific research on freshwater and terrestrial ecosystems has been relatively overlooked. Numerous studies worldwide have highlighted the presence of macroplastics (>2.5 cm) in mountain riverine environments, revealing that even these seemingly pristine ecosystems are not invulnerable to plastic contamination. We investigated the composition and spatial variation of macroplastic debris in the riparian corridors of nine watercourses in Patagonia. Four types of river reaches were assessed: Reference (without urbanization), Upstream-Urban, Urban, and Downstream-Urban, each with varying degrees of urbanization. We analyzed the intrinsic characteristics of the plastics (manufacture and resin type) and environmental factors with possible incidence in plastic distribution (geomorphology, land use, riparian vegetation quality, and climate) during the Southern Hemisphere´s spring season. The most abundant macroplastic debris originated from domestic sources, primarily bags (high- and lowdensity polyethylene), food wrappers (polypropylene), and beverage bottles (polyethylene terephthalate). The number of inhabitants and proximity to urban areas were the strongest drivers of riverside litter accumulation.