Microplastics and fibers from three areas under different anthropogenic pressures in Douro river

Joana C Prata; Veronica Godoy; João P da Costa; Monica Calero; M A Martín-Lara; Armando C Duarte; Teresa Rocha-Santos

doi:10.1016/j.scitotenv.2021.145999

Microplastics and fibers from three areas under different anthropogenic pressures in Douro river

Sci Total Environ. 2021 Jul 1:776:145999. doi: 10.1016/j.scitotenv.2021.145999. Epub 2021 Feb 20.

Authors

Joana C Prata¹, Veronica Godoy², João P da Costa³, Monica Calero², M A Martín-Lara², Armando C Duarte³, Teresa Rocha-Santos³

Affiliations

¹ Centre for Environmental and Marine Studies (CESAM) & Department of Chemistry, University of Aveiro, Aveiro, Portugal. Electronic address: pratajc@ua.pt.
² Department of Chemical Engineering, University of Granada, Granada, Spain.
³ Centre for Environmental and Marine Studies (CESAM) & Department of Chemistry, University of Aveiro, Aveiro, Portugal.

PMID: 33647658
DOI: 10.1016/j.scitotenv.2021.145999

Abstract

Sources contributing to specific concentration of microplastics and fibers are still not completely understood. This study aimed at assessing the concentrations of microplastics (2-5000 μm) and fibers (18-5667 μm) in three areas of distinct influences in the Douro river, Porto, Portugal: (i) a countryside area; (ii) a wastewater treatment effluent release zone; and (iii) an area in proximity to a boat dock and maintenance station. Nile Red staining coupled with microscopy allowed the identification of small microplastics (≥2 μm) with a median concentration of the three areas of 231 MP L^-1. Most were fragments (69%). Sizes <40 μm were the most abundant (84%). Highest concentrations of microplastics were found near the boat dock/maintenance and lowest in the countryside area. Fibers were mostly natural (non-synthetic, 63%). Highest concentrations of fibers were found in the area influenced by the wastewater effluent, especially of synthetic fibers, and lowest in the countryside area. Concentration of all fibers and synthetic fibers was 46 F L^-1 and 6 F L^-1, respectively. High concentrations of microplastics and fiber contamination suggest that the wastewater treatment plant effluent and boat dock/maintenance are the likely sources originating hotspot areas.

Keywords: Douro river; Microplastics; Nile Red; Sources of microplastics.