Future Guanabara Bay Clean-up: Rio de Janeiro’s Hillslope Favelas Ought to Be its Amicable Pinnacles

<p><strong>Abstract:</strong> This article brings a social discussion about the surroundings of Guanabara Bay, showing that there are technological instruments capable of promoting citizenship and quality of life for the inhabitants of the slum areas. The work is part of the collection of published studies on the Guanabara Bay edited by the electronic journal CALIBRE, integrating a fundamental legacy for future projects in urban ecology.</p><p><strong>Key words:</strong> <em>favelas</em>, escalators, Guanabara Bay, Macro-Imagineering, <em>asfaltos</em>, <em>favelados</em>.</p><p>================================================================== </p><p><strong>Resumo:</strong> O presente artigo traz uma discussão social acerca do entorno da Baía de Guanabara, mostrando que há instrumentos tecnológicos capazes de promover cidadania e qualidade de vida para os habitantes das áreas favelizadas. O trabalho se insere na coleção de estudos sobre a Baía de Guanabara publicados no periódico eletrônico CALIBRE, integrando legado fundamental para futuros projetos em ecologia urbana.</p><p><strong>Palavras-chave:</strong> favelas, <em>escalators</em>, Baía de Guanabara, <em>Macro-Imagineering</em>, asfaltos, favelados.</p>

Mercury Methylation Upon Coastal Sediment Resuspension: A Worst-case Approach Under Dark Conditions

Mercury behavior upon resuspension of sediments from two impacted areas of Guanabara Bay was evaluated to assess worst-case methylmercury (MeHg) responses, under dark experimental conditions. Total mercury (THg) and MeHg concentrations were determined along 24 hours experiments of sediment resuspension in the bay water. Fine-grained Meriti River estuary (MR) sediments had 8-times higher MeHg initial concentrations than sandy Rio the Janeiro Harbor (RJH) sediments (3.4 ± 0.29 vs. 0.41 ± 0.1 ng g− 1, respectively).THg contents were uncorrelated with resuspension time, while correlations of resuspension time with MeHg (r2 = 0.66) and %MeHg in relation to THg (r2 = 0.75) were observed only for RJH sediments. These findings correspond to a 2.8-times MeHg concentration increase (ΔMeHg = 0.75 ng g− 1) and 4.4-times increase in %MeHg (Δ%MeHg = 1.0%) for station RJH.This suggests that assessments of MeHg spatial-temporal variability can be limited if concentration changes due to sediment resuspension are not considered.

Short-term changes of anthropogenic eutrophication with precipitation in tropical coastal waters (Guanabara Bay, Rio de Janeiro, Brazil)

&lt;p&gt;Eutrophication in coastal waters caused by non-treated urban discharges has been considered one of the most important effects of global change. At tropical latitudes, nutrient dynamics may be especially intense due to increased metabolic responses supported by high temperatures and solar incidence throughout the year. In addition, short-term variations, such as in rainfall and the tidal regime, may determine important changes in nutrient concentrations and the subsequent trophic status of coastal waters, which are still neglected especially during nocturnal periods due to common logistical constraints. Here, we assessed 24-h variations of water quality during the winter season in a tropical eutrophic bay that receives large inputs of nutrients from non-treated urban effluents (Guanabara Bay, RJ, Brazil). We measured concentrations of dissolved forms of nutrients (nitrate, nitrite, N-ammoniacal, phosphate, and silicate) and carbon (DOC), and oxygen (DO) associated with temperature, salinity, and pH in surface waters each 2h over two daily cycles (July and August 2018). Water samples for nutrients and DOC were preserved for later analysis, while other variables were measured in the field. A biomonitoring system with a submersible pump was used to collect surface coastal waters without bubbling, and along a 70 m pipe from the beach to the field lab. In turn, meteorological data were obtained from a city weather station located ~6 Km from the sampling area. The monthly accumulated precipitation with respect to the 24-h cycle in July was ~70% lower than in August (58 and 16 mm, respectively), although only that in July has showed a rainfall event during the sampling period. As a result, average DOC and N-ammoniacal concentrations in surface waters were ~50% lower, while nitrate, silicate and DO concentrations ~56, 164 and 50 % higher, respectively, during the 24-h cycle in August compared to July. Also, waters were slightly more basic and less saltier in August, contrasting with similar average values of phosphate concentrations and temperature between both sampling periods. Finally, DO concentrations indicated an intense metabolism, varying from a peak of supersaturation with high solar incidence to net autotrophy (2 pm) to undersaturation values as a proxy of net heterotrophy after the nocturnal period (6 am). In conclusion, this short-term study showed that higher monthly accumulated precipitation may dilute high DOC and N-ammoniacal concentrations in coastal aquatic ecosystems undergoing anthropogenic eutrophication. On the other hand, silicate and nitrate concentrations might be related to higher runoff inputs from the watershed. The event of precipitation in July also confirmed a drastic increase in nitrate concentrations, likely due to inputs from the watershed. Therefore, our findings reveal the complexity of accumulated and immediate effects of rainfall on nutrient levels in tropical coastal waters, which &amp;#160;highlight the importance of biomonitoring studies specially in urban areas.&lt;/p&gt;

AMOURINS SHELLMOUND: UNCOVERING BIODIVERSITY AND CHRONOLOGY THROUGH CHARCOAL ANALYSES

ABSTRACT In paleoenvironmental research, several proxies are used to reconstruct climate and vegetation. The establishment of a chronological framework allows for the association of different proxies and correlation of events happening in different geographic areas. Cultural deposits, such as the shellmounds found along the coast of Brazil, play an important role in paleoenvironmental interpretations. Here, we have employed anthracological analysis in charcoal fragments from the Amourins shellmound, located at the margins of the Guanabara Bay, Rio de Janeiro. This allowed for the taxonomic identification and selection of short-lived trees and specific parts of plants for accurate radiocarbon dating. We recorded genera and families typical of the Atlantic Forest, restinga forest, open restinga and mangrove. The 14C ages of charred nuts from different occupational layers range from 3807 ± 35 to 3503 ± 70 BP and a sequential chronological model was built, relating the predominance of mangrove vegetation to the period between 4130–3960 cal BP.

The Devil on a Dying Bay: Brazilian Marine Plasticarianism at Guanabara Bay

<p>This article provides an overview of the known current situation of Guanabara Bay with respect to its pervasive plastic waste pollution, continuing the paired authors' previous works. In addition, the study opens up a broader public discussion on the fundamentals of global degradation, proposing a review of environmental education curriculums including the correct appropriation of the concept of entropy among adults and young people as well. In this sense, the authors deepen the concept and emphasize the importance of considering it in critical reflections on our present-day and future worldly behaviors and actions. Lastly, the work provides some significant and important relevant data and useful references, tracing some lines of thought for building viable solutions, so that the reader can start or continue further studies on the topic addressed herein.</p><p> <strong>Key-words:</strong><strong> </strong>Guanabara Bay,<strong> </strong>entropy, plastic waste, environmental education, global degradation, consumerism.</p><p><strong><span>======================================================================</span> </strong></p><p><strong> </strong>O presente artigo fornece um apanhado geral da situação atual da Baía de Guanabara com respeito à poluição por resíduos plásticos, dando continuidade aos trabalhos anteriores dos autores. Além disso, o estudo abre uma ampla discussão sobre os fundamentos da degradação global, propondo uma revisão dos projetos de educação ambiental incluindo a apropriação correta do conceito de entropia por adultos e jovens. Nesse sentido, os autores aprofundam o conceito e ressaltam a importância de considerá-lo nas reflexões críticas sobre os nossos comportamentos e ações. Por último, o trabalho fornece dados e referências relevantes, traçando algumas linhas de pensamento para a construção de soluções viáveis, de modo que o leitor possa iniciar ou prosseguir estudos complementares sobre o tema.</p><p> <strong>Palavras-chave: </strong>Baía de Guanabara, entropia, resíduos plásticos, educação ambiental degradação global, consumismo.</p>

BILIARY PAH METABOLITES IN FISH FROM THE HIGHLY IMPACTED GUANABARA BAY, IN SOUTHEASTERN BRAZIL, DETERMINED BY FIXED AND SYNCHRONOUS FLUORESCENCE SPECTROSCOPY

Guanabara Bay (GB) covers the metropolitan region of the state of Rio de Janeiro in Brazil. GB is subject to heavy contamination by polycyclic aromatic hydrocarbons (PAHs), from intense oil activities, which pose an ecotoxicological threat. The aim of this study is to implement and optimize a fluorescence methodology for the determination of biliary PAH metabolites in fish species (burrfish and whitemouth croaker), in order to evaluate biliary PAH metabolites as a biomarker of exposure. Fish were sampled from GB and a control region. Naphthalene, pyrene and benzo(a)pyrene metabolites were determined by Fixed Fluorescence Method (FF), while 1-hydroxypyrene was assessed by Synchronous Fluorescence Spectroscopy (SFS). The implementation and optimization of the FF and SFS methods allowed the determination and evaluation of the exposure of these species to PAHs of pyrogenic and petrogenic origin. Biliary PAH metabolite determinations was proven to be a useful tool for environmental monitoring contamination assessments.