in this study, we analyzed the bioconcentration of cd, cr, cu, pb, ni, and Zn in the soft tissue of transplanted oysters in two sites in the potengi estuary for six months. native oysters collected before and after the transplantation experiment provided the background for statistical analyses. cd, cr, and ni showed a strong inverse correlation with oyster weight in both sites. transplantation upstream of the estuary presented increasing concentrations of Zn, cu, and pb and condition index (ci) and decreasing trends for Cd and Ni, whereas Cr oscillated significantly. In the downstream transplantation, cu, pb, and Zn and the ci tended to decrease, whereas for ni, cd, and cr, the concentrations increased. Spatiotemporal principal component analysis correlated these results mainly with proximity to the polluting source, seasonality, and previous exposure to heavy metals. these results helped interpret the responses provided by these biomonitors to environmental changes, whether they are natural or anthropogenic.Industrialization and urbanization are primary sources of heavy-metal contamination in estuaries and coastal ecosystems of tropical and subtropical countries (e.g., Brazil) 1,2 . Deforestation of estuarine margins also impairs the ability of the environment to withstand heavy-metal pollution, as mangrove forests are an important agent in the process of cycling organic matter and nutrients, acting as a "filter" by retaining and detoxifying harmful elements and substances 3-5 . It is a fact that metal pollution in aquatic systems will significantly increase in the future owing to the popularity of new technologies, such as nanotechnology, and the improper disposal of the so-called e-waste 6 .Metals widely available in estuarine environments tend to be trapped in sediments and incorporated into the local food chain. Thus, the presence of heavy metals in sediments can induce toxic effects in living organisms when they exceed certain concentration limits 5 . These limits, according to Farrington et al. 2 , are dependent on the half-life of the metal itself (or the metallic compound) and its nature (whether essential or nonessential) and on the tolerance of the organism to the environment it is exposed to. Once discarded in an estuarine system, heavy metals can undergo various processes, such as dissolution, precipitation, adsorption, and complexation (with organic and inorganic dissolved ligands and particulate matter), and become deposited in bottom sediments 7 . These processes can create a potential source of pollution and adversely affect the environmental quality 8,9 . Certain marine organisms, such as barnacles and bivalve mollusks, can metabolically accumulate large amounts of these metals in their tissues, having efficient strategies to tolerate toxicity and reduce damage in such a way that they can be employed in multipurpose environmental monitoring and several levels of environmental degradation, thus signifying the extent of pollution present in the adjacent water column 10,11 .Bioaccumulation of he...

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The quantitative assessment of the carbonate system represents one of the biggest challenges toward the "Sustainable Development Goals" defined by the United Nations in 2015. In this sense, the present study investigated the Spatio-temporal dynamics of the carbonate system and the effects of the El Niño and La Niña phenomena over the Cabo Frio upwelling area. The physical characterization of the site was carried out through data on wind speed and sea surface temperature. Water samples were also collected during the oceanographic cruise onboard the Diadorim R/V (Research Vessel). From these samples, the parameters of absolute and practical salinity, density, pH, total alkalinity, carbonate, calcite, aragonite, bicarbonate dissolved inorganic carbon, carbon dioxide, partial pressure of carbon, calcium, and total boron were obtained. The highest average concentration of bicarbonate in S1 (2018 µmol/kg) seems to contribute to the dissolved inorganic carbon values (2203 µmol/kg). The values of calcite saturation state, aragonite saturation state, and carbonate were higher on the surface of each station (calcite saturation state = 4.80–5.48; aragonite saturation state = 3.10–3.63, and carbonate = 189–216 µmol/kg). The mean values of pH were similar in the day/night samples (7.96/7.97). The whole carbonate system was calculated through thermodynamic modeling with the Marine Chemical Analysis (AQM) program loaded with the results of the following parameters: temperature, salinity, total alkalinity, and pH parameters. This manuscript presents original data on the carbonate system and the "acidification" process influenced by the Cabo Frio upwelling, which directly depends on the El Niño and La Niña phenomena oscillations in the sea surface temperature.

RESUMO Áreas de mangue estão sujeitas a pressões antrópicas, ecossistema deposicional, e seus sedimentos contêm registros da história ambiental. Recentemente, foi criada uma Área de Preservação Ambiental na região de manguezais de São Gonçalo (Área de Preservação Ambiental de Itaoca). Esse local recebeu lixo doméstico ao longo de 28 anos. O perfil sedimentar determinou a geocronologia e quantificou os poluentes orgânicos persistentes, como hidrocarbonetos policíclicos aromáticos, bifenilas policloradas e pesticidas organoclorados. Os hidrocarbonetos policíclicos aromáticos apresentaram origem pirogênica com concentrações moderadas, exceto para o dibenzo [a,h] antraceno, um composto carcinogênico que excedeu o nível de efeito limítrofe. O registro sedimentar correspondente ao período anterior ao lixão sugeriu que os hidrocarbonetos policíclicos aromáticos estavam ligados à queima de madeira por olarias. O perileno foi um bom marcador para a redução da biomassa vegetal, sugerindo associação com a supressão de manguezais durante a ocupação. No período que antecede ao lixão, antes de 1976, a contaminação do sedimento por pesticidas organoclorados, como [2,2-bis (p-clorofenil) −1,1dicloroetileno] (metabólito primário do [1,1,1-tricloro-2,2-bis (p-clorofenil) etano]), foi vinculada a campanhas de saúde pública no combate ao mosquito da malária, ultrapassando os valores de nível de efeito limítrofe. No período de atividade do lixão, o aumento dos valores de [2,2-bis (p-clorofenil) −1,1dicloroetileno] coincidiu com o banimento do [1,1,1-tricloro-2,2-bis (p-clorofenil) etano], sugerindo seu descarte irregular. As bifenilas policloradas estavam abaixo das concentrações de nível de efeito limítrofe, mas semelhantes aos encontrados em lixões industriais em outros países. Os poluentes orgânicos persistentes mostraram-se eficientes marcadores antrópicos de ocupação urbana e contaminação acarretada pelo lixão. Por estar localizado em área de proteção ambiental, é necessária a retomada imediata do processo de remediação para interromper o processo de contaminação da Área de Preservação Ambiental em questão.

The Sepetiba Bay (SB), located in the state of Rio de Janeiro (SE Brazil), is a transitional ecosystem highly anthropized. Because of its great environmental, economic, and social importance, the SB has been the target of several studies to investigate the sources of pollution and their environmental impact. However, studies on the response of foraminifera to pollution are rare. This study applies for the first time in the SB the Ecological Quality Ratio (EQR) based on the biotic index exp(H’bc), related to foraminiferal diversity, coupled with granulometric, mineralogical, and geochemical data and a robust age model (based on 210Pb and 137Cs activity). This study aims to evaluate the paleo-ecological quality status (PaleoEcoQS) along core SP5, collected in the inner central region of the SB. In the sedimentary record of the first half of the 20th century, no foraminifera were found, and the moderate enrichment in lithogenic elements was probably related not only to weathering and erosion of rocks but also to mining activities in the region. From the second half of the 20th century, the study area was under higher marine influence. Progressive siltation took place because of anthropogenic interventions in river courses, eutrophication, and metal pollution. Weak hydrodynamic conditions favored the accumulation of fine-grained sediments and organic matters. In the same period, low diversified benthic foraminiferal assemblages, including mainly opportunist species, were developed. Paleo-ecological conditions inferred by the biotic index exp(H’bc) were poor around 1970 and worsened after the metal spill released by Companhia Ingá Mercantil (a zinc ore processing plant). After that, progressively recovery has led to good ecological conditions in 2015. This study shows how benthic foraminiferal methods could represent a very useful tool to track changes in the evaluation of PaleoEcoQS.