Microplastics in the Amazon biome: State of the art and future priorities

Abstract

Microplastics (MPs) have been identified as a major potential threat to the biota and human health. Despite the exponential increase in MP research worldwide, few studies have focused on the extensive Amazon biome. To assess research priorities, the present study reviewed and summarized the available scientific knowledge on MPs in the Amazon, in addition to analyzing population and waste-management data, to evaluate potential sources of MPs in the hydrographic system. Poor sanitation conditions are a main source of MPs for the vast hydrographic basin, and, consequently, for the adjacent ocean. Secondary MPs predominated, mostly fibers (96% of debris), composed of polyamide (32%). Mean MP concentrations ranged from 0.34 to 38.3 particles.individual^-1 in biota, 5 to 476,000 particles.m^-3 in water, and 492.5 to 1.30848 × 10⁷ particles.m^-3 in sediment, values in close comparison with those found in areas profoundly affected by anthropogenic pollution. MPs were widespread in a range of Amazonian environments and species, and negative effects are probably occurring at various ecological levels. However, limited research, methodological constraints, flaws and the lack of standardization, combined with the continental dimensions of the Amazon, hampers the collection of the fundamental knowledge needed to reliably evaluate the impacts and implement effective mitigation measures. There is an urgent need to expand scientific data available for the region, improving local research infrastructure, and training and deploying local researchers.

Keywords: Plastic debris; Pollution; Review; SDG 14; South atlantic.

Graphical abstract

Fig. 1

Delimitation of the Amazon biome and collection sites of the microplastic studies identified in the region. The images were acquired by the BaseMap tool of the QGis 3.16.5 software, and obtained through the QuickMapServices 0.19.16 plugin, data source: ESRI Satellite.

Fig. 2

Basic sanitation index (BSI) and percentage of urban coverage served by sanitation services in the municipalities of the Brazilian Amazon region. The BSI was determined by summing the urban service coverages and diving the obtained value by 100 to normalizing the index as a rational number from 0 to 3. The BSI was categorized as follows: Precarious (BSI = 0), Low (BSI > 0–1), Moderate (BSI > 1–2), and Adequate (BSI >2). The images were acquired by the BaseMap tool of the QGis 3.16.5 software, and obtained through the QuickMapServices 0.19.16 plugin, data source: ESRI Satellite. Data on public sewage collection, rainwater-drainage systems, and solid-waste disposal systems obtained from the websites of the Brazilian National Waters and Public Sanitation Agency (ANA) and the National Public Sanitation System (SNIS).

Fig. 3

Population density (number per km²) in the Amazon biome. Images acquired by the BaseMap tool of the QGis 3.16.5 software and obtained through the QuickMapServices 0.19.16 plugin. Population data obtained from the websites of the Brazilian Institute for Geography and Statistics (IBGE), the Colombian National Administrative Department of Statistics (DANE), the Guyanese Bureau of Statistics (BoS), the Surinamese General Bureau of Statistics (ABS), the Venezuelan National Institute of Statistics (INE), the Ecuadorian National Institute of Statistics and Censuses (INEC), the Peruvian National Institute of Statistics and Informatics (INEI), and the National Institute of Statistics of Bolivia (INE).

Fig. 4

The distribution of the 23 published papers on microplastic (MP) pollution in the Amazon identified in the present study, according to A: year of publication; B: sector of the basin; C: matrix analyzed; D: research topic; E: reported MP shapes; and F: polymer composition. ABS: Acrylonitrile Butadiene Styrene; EVA: Ethylene-Vinyl Acetate; HDPE: High-Density Polyethylene; PET: Polyethylene Terephthalate; PVC: Polyvinyl Chloride.

Fig. 5

Scatter plot between population density and microplastic frequency of occurrence (FO) reported in literature. Shaded area indicates 95% confidence interval for the linear regression. R² = 0.1074, F = 9.747, p = 0.00249, y = 52.50 + 0.22x.