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Marajó Island, an environmental protection area for sustainable use in the Brazilian Amazon, was the first region in Brazil to apply the pesticide DDT, a persistent organic pollutant (POP), to control malaria outbreaks. This study investigated background levels of various POPs, including o,p'- and p,p'-DDT and their primary metabolites (o,p'- and p,p'-DDE, o,p'- and p,p'-DDD), as well as hexachlorocyclohexane (α-, β-, γ-, δ-HCH), using estuarine surface sediments and sediment cores from areas influenced by urbanization and agriculture. All samples were collected during the dry season (September 2014). Surface sediments exhibited ΣDDT concentrations up to 2.71 ng g⁻ 1 , with isomeric ratios indicating past DDT application and contributions from dicofol. Sediment profiles revealed alternating aerobic and anaerobic degradation processes of DDT. Other organochlorinated contaminants were not detected. The presence of γ-HCH as the main isomer (0.24 to 0.90 ng g⁻ 1 ) in surface samples suggests recent lindane application as a wood preservative or cattle parasite treatment. A dated sediment core revealed historical contamination of early DDT tests in the Amazon during the mid-1940s. Increasing ΣDDT concentrations (up to 12.3 ng g⁻ 1 ) were identified in the 1970s, coinciding with the intensification of DDT use for public health campaigns, which lasted until 2009 and reached the highest ΣDDT flux. Legal restrictions on the use and commercialization of POPs, along with natural degrading processes, likely led to decreased accumulation and limited ecological risks. Furthermore, the low concentrations of POPs suggested biodegradation and dispersion from northeast to southeast., Competing Interests: Declarations. Ethical approval: This study was authorized by the Chico Mendes Institute for Biodiversity (ICMBio/SISBIO 49140–1). Consent to participate: The authors consent to participate in this study. Consent for publication: The authors consent to publish the study. Competing interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Mercury (Hg) is a toxic globally spread pollutant that has been found at increasing concentrations in the South Atlantic Ocean. The present work provides the first insight into the total mercury (HgT, unfiltered waters) content in the water of the Brazilian Exclusive Economic Zone (BEEZ), within a 24°S to 20°S. Water samples were collected from surface to 3400 m depth along transects, and analyzed with atomic fluorescence. The mean HgT concentration for the Tropical Water mass (TW) was 6.3 ± 1.4 pM (n = 16), for the South Atlantic Central Water (SACW), 5.9 ± 0.7 pM (n = 8), for the Antarctic Intermediate Water (AAIW), 5.0 ± 0.6 pM (n = 2), for the Upper Circumpolar Deep Water (UCDW), 6.5 pM (n = 1), and for the North Atlantic Deep Water (NADW), 5.7 ± 0.9 pM (n = 12). HgT concentrations were highest throughout the BEEZ in comparison with other parts of the Atlantic Ocean, farther from the coast., (Copyright © 2022 Elsevier Ltd. All rights reserved.)