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The trash trail to the sea

UN study names the Brazilian cities that dispose of the most plastic waste and the rivers that transport it

Towns and river networks in the interior of Brazil have been examined in an attempt to determine the origins of the plastic bottles, shampoo containers, cotton buds, plastic bags, disposable cups and cutlery, polystyrene boxes, and other plastic materials polluting the sea along the Brazilian coastline. In an analysis released in October by Blue Keepers, a project that is part of the United Nations (UN) Global Compact’s Water and Ocean Action Platform in Brazil, seven cities without marine beaches—Manaus, Teresina, Brasília, Goiânia, Campo Grande, Belo Horizonte, and Contagem—were identified as the biggest sources of plastic waste that reaches the sea, mainly via the Amazon, Tocantins, São Francisco, Tietê, and Paraná rivers and their tributaries. In addition to these are coastal cities from Belém in the North to Porto Alegre in the South, including two state capitals near the coast: São Paulo and Curitiba.

The diagnosis, which took a number of factors into account, including income per capita, sanitation index, and other indicators detailed in an article published in the Journal of Environmental Management in October, identified northern Brazil as one of the biggest sources of plastic waste in the environment. One potential explanation is a lack of recycling centers and the vast hydrographic network in the region. The region that discards the most waste, due to its high population density, is the Southeast, in addition to parts of the Midwest and the South, whose rivers flow into the Paraná River.

The Blue Keepers study indicated that the locations where plastic waste was most likely to enter the ocean were the Amazon River mouth, the city of Belém, the São Francisco River mouth, Guanabara Bay, Lagoa dos Patos lagoon, and the mouth of the La Plata River, which continues from the Paraná River. Scientists from the Oceanographic Institute (IO), the Institute for Advanced Studies (IEA), and the School of Arts, Sciences, and Humanities (EACH), all at the University of São Paulo (USP), and the Federal Institute of Rio Grande do Sul (IFRS) participated in the study, with support from Braskem and Ocean Pact (see map).

“The movement of plastics towards rivers and the sea depends a lot on rainfall, the relief of the terrain, and the wind,” said Alexander Turra, a researcher at IO and UNESCO Chair for Ocean Sustainability at the IEA, when the preliminary results of the survey were presented at the Oceanic Culture Dialogues conference held in Santos, São Paulo, in October. According to him, the wind can carry waste from sanitary landfills situated on riverbanks.

“The problem is not just with coastal populations, but also with the interior of the country; we need to take this information into every Brazilian’s home to prevent plastic waste from reaching the sea,” said Gabriela Otero, coordinator of Blue Keepers. The two main goals of this UN project are to reduce the amount of plastic reaching the coast of Brazil and to strengthen solid waste management in 100 Brazilian municipalities by 2030.

Alexandre Affonso

Priority cities
The first city to be monitored is Rio de Janeiro. Other priority municipalities are Manaus, Belém, São Luís, Fortaleza, Natal, João Pessoa, Recife, Maceió, Aracaju, Salvador, Vitória, São Paulo, Baixada Santista, and Porto Alegre. Measures to reduce the amount of plastic waste are part of the Ocean Decade objectives established by the UN in 2020. It is estimated that 150 million tons of plastic are circulating in marine waters worldwide today.

According to the Blue Keepers study, each Brazilian throws out an average of 16 kilograms of plastic per year, much of which presents a high risk of reaching the sea. Higher volumes were recorded in municipalities on the South and Southeast coast with large populations that increase during the summer months and public holidays. The survey also found that 3.4 million tons of plastic discarded by Brazilians reach the ocean each year, equivalent to 47.8% of the 7.1 million tons of plastic processed in the country in 2021, according to the Brazilian Association for the Plastic Industry (ABIPLAST).

The study indicated that plastic waste collection should be considered regionally rather than at the level of the municipality, which may not necessarily be the source, but could be the destination of unwanted materials. Marcos Libório, environmental secretary for the city of Santos, agreed: “Our beach is cleaned daily, but this isn’t enough. We need to work together with the other nine municipalities in the Baixada Santista region.”

Because it is a tourist city, the population of Santos increases from 433,000 residents to around 1.5 million in the sunny summer months, with the volume of plastic products reaching the sea also increasing as a result. In campaigns carried out between autumn 2019 and summer 2020, a team of researchers from the Federal University of São Paulo (UNIFESP), the Federal University of Pernambuco (UFPE), and the Blue Sea Institute (IMA) picked up 62,638 items of litter from the city’s beaches. Of that number, the proportion that was plastic, including polystyrene foam used in packaging, ranged from 64.8% to 72.5%, as described in a study published in Marine Pollution Bulletin in February 2021.

Brazil’s National Solid Waste Policy, approved in 2010, sets targets for reducing, reusing, recycling, and disposing of waste in an environmentally friendly manner over the next 20 years. In 2020, 74.4% of Brazilian municipalities had implemented recyclable waste collection to some extent, which is one way to achieve these objectives, but 25.6% continued to dispose of all waste without any sorting, which is against current regulations, according to the 2021 Solid Waste Report by the Brazilian Association of Public Cleaning and Special Waste Companies (ABRELPE). Karen de Oliveira Silverwood-Cope, general coordinator of Oceans, Antarctica, and Geosciences at Brazil’s Ministry of Science, Technology, and Innovation (MCTI), highlights that there are still no rules on managing plastic already dumped in the environment.

Scientific articles
ALENCAR, M. V. et al. How far are we from robust estimates of plastic litter leakage to the environment. Journal of Environmental Management. vol. 323 116195 pp. 1–11. oct. 2, 2022.
RIBEIRO, V. V. et al. Marine litter on a highly urbanized beach at Southeast Brazil. Marine Pollution Bulletin. vol. 163 111978 pp. 1–8. sept. 2021.