Protocol for the quantification of microplastics in aquatic environments: a case study of the Itabapoana river

Authors

DOI:

https://doi.org/10.19180/2177-4560.v20n22026p27-43

Keywords:

Microplastics, Environmental monitoring, Itabapoana River

Abstract

Water quality assessment is essential for the integrated management of water resources; however, traditional indicators such as the Water Quality Index (WQI) and the Trophic State Index (TSI) do not encompass emerging contaminants such as microplastics. The occurrence of microplastics in aquatic ecosystems represents a growing environmental concern, and the detection and quantification of these particles are essential to support risk assessments, guide monitoring strategies, and inform public policies aimed at mitigating plastic pollution. This study presents a methodological protocol for the quantification of microplastic particles in surface water samples, integrating in situ sampling, simplified laboratory processing, and an automated image analysis approach validated by manual counting. The protocol was applied as a case study in the Itabapoana River Basin, which extends across the Brazilian states of Espírito Santo, Minas Gerais, and Rio de Janeiro. Samples were collected during four seasonal field campaigns, two in the dry season and two in the wet season of 2024, with 150 liters of water filtered per campaign. An image-processing algorithm was developed in Python to identify and quantify dark microplastic particles with regular morphology. The concentrations ranged from 0.022 to 0.081 MP/m³, values lower than those reported for other Brazilian rivers, which can be attributed both to basin-specific characteristics and to methodological constraints, as fibers and light-colored particles were not detected. Despite these limitations, the proposed methodology provides a reproducible and simplified approach, enabling preliminary and comparative monitoring of microplastics in fluvial systems and serving as an effective analytical tool for environmental assessment and water quality management.

Downloads

Download data is not yet available.

Author Biographies

  • Flávia Chrys´óstomo Silva , Fluminense Federal Institute (Campos dos Goytacazes Campus)
    PhD candidate in Modeling and Technology for the Environment Applied to Water Resources at the Federal Fluminense Institute (AmbHidro), Campos dos Goytacazes (RJ), Brazil.
  • Nikolas Gomes Silveira de Souza, Fluminense Federal Institute (Campos dos Goytacazes Campus)
    Doctorate in Modeling and Technology for the Environment Applied to Water Resources (AmbHidro) from the Federal Fluminense Institute - Campos dos Goytacazes/RJ - Brazil.
  • Isadora Azevêdo dos Santos, Fluminense Federal Institute (Campos dos Goytacazes Campus)
    Bachelor's degree in Natural Sciences from the Federal Fluminense Institute - Campos dos Goytacazes (RJ), Brazil.
  • Manildo Marcião de Oliveira, Fluminense Federal Institute (Cabo Frio Campus)
    Doctor of Science (UERJ). Professor at the Federal Institute of Education, Science and Technology Fluminense - Cabo Frio campus (RJ) – Brazil.
  • Vicente de Paulo Santos de Oliveira, Fluminense Federal Institute (Campos dos Goytacazes Campus)
    Doctor of Agricultural Engineering (UFV). Professor at the Federal Institute of Education, Science and Technology Fluminense - Campos dos Goytacazes campus (RJ) – Brazil.
  • Thiago Moreira de Rezende Araújo, Fluminense Federal Institute (Campos dos Goytacazes Campus)
    Doctor of Natural Sciences (UENF). Professor at the Federal Institute of Education, Science and Technology Fluminense - Campos dos Goytacazes campus (RJ) – Brazil.

References

ABBAS, G.; AHMED, U.; AHMAD, M. A. Impact of Microplastics on Human Health: Risks, Diseases, and Affected Body Systems. Microplastics, v. 4, n. 2, art. 23, 2025. DOI: https://doi.org/10.3390/microplastics4020023

AGERH – Agência Estadual de Recursos Hídricos do Espírito Santo. De Olho no Rio: Itabapoana. Vitória: AGERH, 2019. Disponível em: https://agerh.es.gov.br/. Acesso em: 05 set. 2025.

AGEVAP – Associação Pró-Gestão das Águas da Bacia Hidrográfica do Rio Paraíba do Sul. Relatório Síntese – Caracterização Hidrográfica do Rio Itabapoana. Resende: AGEVAP, 2019. Disponível em: https://www.agevap.org.br/. Acesso em: 05 set. 2025.

AGÊNCIA NACIONAL DE ÁGUAS E SANEAMENTO BÁSICO (ANA). ANA e ABDI lançam edital para soluções que reduzam a presença de plástico nas águas brasileiras. 2 jun. 2023. Disponível em: https://www.abdi.com.br/abdi-e-ana-abrem-edital-para-selecionar-solucoes-que-reduzam-plastico-nas-aguas/. Acesso em: 12 set. 2025.

ANDRADY, A. L. Microplastics in the marine environment. Marine Pollution Bulletin, v. 62, n. 8, p. 1596-1605, 2011. DOI: https://doi.org/10.1016/j.marpolbul.2011.05.030

ARJU, M. Z. B. Z. et al. Deep-learning enabled rapid and low-cost detection of microplastics using mobile phone microscopy. Scientific Reports, v. 15, p. 8180, 2025. DOI: https://doi.org/10.1039/D4RA07991D

BROWNE, M. A. et al. Linking effects of anthropogenic debris to ecological impacts. Proceedings of the Royal Society B: Biological Sciences, v. 282, n. 20142929, p. 1-10, 2015.

CETESB – Companhia Ambiental do Estado de São Paulo. Relatório de qualidade das águas interiores do Estado de São Paulo 2024. São Paulo: CETESB, 2024.

CONAMA – Conselho Nacional do Meio Ambiente. Resolução nº 357, de 17 de março de 2005. Dispõe sobre a classificação dos corpos de água e diretrizes ambientais para seu enquadramento. Diário Oficial da União, Brasília, 18 mar. 2005.

DRABINSKI, T. L. et al. Microplastics in Freshwater River in Rio de Janeiro and Its Role as a Source of Microplastic Pollution in Guanabara Bay, SE Brazil. Micro, v. 3, p. 208-223, 2023. DOI: https://doi.org/10.3390/water5010015.

GESAMP – Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection. Sources, fate and effects of microplastics in the marine environment: a global assessment. http://www.gesamp.org/publications/reports-and-studies-no-90 Joint Group, Rep. Stud. GESAMP n. 90, 2015.

IEMA – Instituto Estadual de Meio Ambiente e Recursos Hídricos. Estudo de Impacto Ambiental do Complexo Hidrelétrico do Rio Itabapoana. Vitória, 2002. Disponível em: https://iema.es.gov.br/Media/iema/CQAI/EIA/2002/Complexo%20hidrel%C3%A9trico%20do%20rio%20Itabapoana/EIA%20ITABAPOANA.pdf. Acesso em: 10 set. 2025.

LAMPARELLI, M. C. Graus de trofia em corpos d’água do Estado de São Paulo: avaliação dos métodos de monitoramento. 2004. Tese (Doutorado em Ciências) – Universidade de São Paulo, São Paulo, 2004.

LEBRETON, L. C. M. et al. River plastic emissions to the world’s oceans. Nature Communications, v. 8, n. 15611, p. 1-10, 2017. DOI: 10.1038/ncomms15611.

LI, J.; LIU, H.; CHEN, J. P. Microplastics in freshwater systems: A review on occurrence, environmental effects, and methods for microplastics detection. Water Research, v. 137, p. 362-374, 2018. DOI: https://doi.org/10.1016/j.watres.2017.12.056.

LI, Y.; TAO, L.; WANG, Q.; et al. Potential Health Impact of Microplastics: A Review of Environmental Distribution, Human Exposure, and Toxic Effects. Environmental Health, v. 1, n. 4, p. 249-257, 2023. DOI: 10.1021/envhealth.3c00052.

LI, J.; WANG, Y.; TANG, R.; LIU, Y. Microplastics in inland waters: Sources, fate, and implications for freshwater ecosystems. Science of the Total Environment, v. 906, p. 167743, 2024. DOI: https://doi.org/10.1016/j.scitotenv.2024.167743.

LUO, Q.; TAN, H.; YE, M.; et al. Microplastics as an emerging threat to human health: An overview of potential health impacts. Journal of Environmental Management, v. 387, 125915, 2025. DOI: 10.1016/j.jenvman.2025.125915.

MAGNI, S.; BINELLI, A.; PITTURA, L.; AVIO, C. G.; DELLA TORRE, C.; PARENTI, C. C.; GORBI, S.; REGOLI, F. The fate of microplastics in an Italian wastewater treatment plant. Science of the Total Environment, v. 652, p. 602-610, 2019. DOI: https://doi.org/10.1016/j.scitotenv.2018.10.269

MAPBIOMAS BRASIL. Coleção 10 – Cobertura e uso da terra (1985–2024): Bacia Hidrográfica do Rio Itabapoana. 2024. Disponível em: https://brasil.mapbiomas.org/estatisticas/. DOI: https://doi.org/10.58053/MapBiomas/IBQPF6

MESQUITA, P. et al. A low-cost microfluidic method for microplastics identification. Micromachines, v. 13, n. 4, p. 593, 2022. DOI: https://doi.org/10.3390/mi13040593

MONTAGNER, C. C.; DIAS, M. A.; PAIVA, E. M.; VIDAL, C. Microplásticos: ocorrência ambiental e desafios analíticos. Química Nova, v. 44, n. 7, p. 856-867, 2021.

NASCIMENTO, R. C. M.; COSTA, C. R.; CAVALCANTI, J. S. S.; COSTA, M. F. Seasonal variability of water quality parameters in an urban tropical estuary (Northeast Brazil). Revista Ibero-Americana de Ciências Ambientais, v. 13, n. 9, p. 278-293, 2022. DOI: http://doi.org/10.6008/CBPC2179-6858.2022.009.0022.

NOAA – National Oceanic and Atmospheric Administration. Marine debris program: microplastics. Silver Spring: NOAA, 2009.

OTSU, N. A threshold selection method from gray-level histograms. IEEE Transactions on Systems, Man, and Cybernetics, v. 9, n. 1, p. 62-66, 1979. DOI: https://doi.org/10.1109/TSMC.1979.4310076.

PRATA, J.; DA COSTA, J.; DUARTE, A.; ROCHA-SANTOS, T. Methods for sampling and detection of microplastics in water and sediment: a critical review. TrAC – Trends in Analytical Chemistry, v. 110, 2018. DOI: https://doi.org/10.1016/j.trac.2018.10.029.

SAUVOLA, J.; PIETIKÄINEN, M. Adaptive document image binarization. Pattern Recognition, v. 33, n. 2, p. 225-236, 2000. DOI: https://doi.org/10.1016/S0031-3203(99)00055-2.

SHIM, W. J.; HONG, S. H.; EO, S. E. Identification methods in microplastic analysis: a review. Analytical Methods, v. 9, n. 9, p. 1384-1391, 2017. DOI: https://doi.org/10.1039/C6AY02558G

UNEP – United Nations Environment Programme. Marine plastic debris and microplastics: global lessons and research to inspire action and guide policy change. Nairobi: UNEP, 2016.

VASUDEVA, M.; WARRIER, A. K.; KARTHA, V. B.; UNNIKRISHNAN, V. K. Advances in microplastic characterization: spectroscopic techniques and heavy metal adsorption insights. TrAC – Trends in Analytical Chemistry, v. 183, p. 118111, 2025. DOI: https://doi.org/10.1016/j.trac.2024.118111.

WANDER, L. et al. Development of a low-cost method for quantifying microplastics in soils and compost using near-infrared spectroscopy. Measurement Science and Technology, v. 33, n. 7, p. 075801, 2022. DOI: https://doi.org/10.1088/1361-6501/ac5e5f

WANG, W.; NDUNGU, A. W.; LI, Z.; WANG, J. Microplastics pollution in inland freshwaters of China: a case study in urban surface waters of Wuhan, China. Science of the Total Environment, v. 575, p. 1369-1374, 2017. DOI: https://doi.org/10.1016/j.scitotenv.2016.09.213.

ZHANG, X.; YU, C.; WANG, P.; YANG, C. Microplastics and human health: unraveling the toxicological pathways and implications for public health. Frontiers in Public Health, v. 13, p. 1567200, 2025. DOI: https://doi.org/10.3389/fpubh.2025.1567200.

Downloads

Published

10-11-2026

Issue

Vol. 20 No. 2 (2026): Boletim do Observatório Ambiental - IFF

Section

Original articles

License

Copyright (c) 2026 Flávia Chrys´óstomo Silva , Nikolas Gomes Silveira de Souza, Isadora Azevêdo dos Santos, Manildo Marcião de Oliveira, Vicente de Paulo Santos de Oliveira, Thiago Moreira de Rezende Araújo

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

The authors of the manuscript submitted to Boletim do Observatório Ambiental Alberto Ribeiro Lamego, hereby represented by the corresponding author, agree to the following terms:

The authors retain the copyright and grant Boletim do Observatório Ambiental Alberto Ribeiro Lamego the right of first publication.

At the same time the work is licensed under the Creative Commons Attribution 4.0 International License, allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon its content for any legal purpose, even commercially, provided the original work is properly cited.

Authors will not receive any material reward for the manuscript and Essentia Editora will make it available online in Open Access mode, through its own system or other databases.

Authors are authorized to enter into additional contracts separately for non-exclusive distribution of the version of the work published in Boletim do Observatório Ambiental Alberto Ribeiro Lamego (eg, publish in institutional repository or as book chapter), with acknowledgment of authorship and initial publication in this journal.

Authors are permitted and encouraged to publish and distribute their work online (eg, in institutional repositories or on their personal page) at any point after the first publication of the article by Boletim do Observatório Ambiental Alberto Ribeiro Lamego.

Essentia Editora may make normative, orthographic and grammatical changes in the originals in order to maintain the standard language, with the final consent of the authors.

The content and opinions expressed in the manuscript are the sole responsibility of the author (s).

How to Cite

Protocol for the quantification of microplastics in aquatic environments: a case study of the Itabapoana river. Boletim do Observatório Ambiental Alberto Ribeiro Lamego, [S. l.], v. 20, n. 2, p. 27–43, 2026. DOI: 10.19180/2177-4560.v20n22026p27-43. Disponível em: https://editoraessentia.iff.edu.br/index.php/boletim/article/view/23614.. Acesso em: 11 nov. 2026.