Assessment and Comparison of Microplastic Contamination in Atlantic Navigation Routes with Known Uncertainty

Low microplastic contaminationin the open Atlantic Oceanwith contamination spots close to cities being contaminated, normalizedfor ship's path length and water volume, compared for 99% confidencelevel. Microplastics (MP) have been foundin various environments worldwide.However, not many studies focus on the open ocean due to logisticalrestraints. Between January and May 2020, the NRP Sagres sampled 123linear paths of subsurface water of the Atlantic Ocean, passing byCape Verde, the east coast of South America, and the west coast ofAfrica. The water was sampled through the ship's water system.The membranes were analyzed by the Hydrographic Institute of Portugaland the Norwegian Institute for Water Research by micro-FTIR. Thecontamination levels were reported with uncertainty, for 99% confidencelevel (CL), normalized for filtered water volume and the distancetraveled during sampling. Uncertainties were calculated through adetailed & DPRIME;bottom-up & DPRIME; evaluation. MP were found in abouta third of the stations (48 out of 123), and most of those stations(43 out of 48) presented concentrations below 1 m(-3) km(-1). The siteswhere higher concentrations were registered were the port of the islandof Santiago (Cape Verde) ((5.9 & PLUSMN; 5.2) m(-3) km(-1)), the Guanabara Bay in Riode Janeiro (Brazil) ((41 & PLUSMN; 27) m(-3) km(-1)), and close to South Africa ((4.9 & PLUSMN; 2.4) m(-3) km(-1)). Most MPfound were polyamide, polyester, polyethylene, ethylene vinyl acetate,and poly(methyl methacrylate). The estimated contamination levelscannot be directly compared with information obtained in other studiesdue to differences in how MP were determined and the unknown uncertaintyof their measured values. This article presents a relevant and reliablecontribution to understanding the MP distribution in the AtlanticOcean.