On May 2019, the members of the Anthropocene Working Group completed a binding vote to affirm some of the key questions that have been agreed in 2016: the Anthropocene should be considered as a formal chronostratigraphic unit, defined by a Global Boundary Stratotype Section and Point (GSSP), using one of the stratigraphic signals around the mid-twentieth century of the Common Era. The fallout from nuclear weapons testing appears as the most suitable GSSP. In this article, the main anthropogenic markers are discussed as well as the sources or human-made radiation and the signature of nuclear weapons testing. The appearance of 239+240Pu in the early 1950s and the clear peak, in 1963, makes a good marker. High resolution archives include layers of sedimentary rocks, lacustrine and marine sediments and corals and polar ice cores. A coupled application of other radioactive isotopes, as 137Cs, 14C and 241Am, may be useful to categorize distinct fallout signatures. A site to define the Anthropocene (golden spike) would ideally be located between 30º and 60º north of the equator. Nevertheless, results obtained in sediments on the Brazilian coast showed that both 239+240Pu and 137Cs signatures could be detected and quantified as markers of this “atomic age”.

ABSTRACT The potential mobility of Cd, Cr, Cu, Ni, Pb and Zn in soils severely impacted by inadequate storage of industrial wastes in Rio de Janeiro State (Brazil) was evaluated by applying the Toxicity Characteristic Leaching Procedure (TCLP). This procedure allowed the estimation of toxicity risks for Cd, Cr and Pb. In a contamination hotspot within the study area, the following order of metal concentrations was observed: Pb > Zn > Cu > Ni > Cd > Cr, with significantly higher values than observed for a control site. Decades of soil exposure to wastes implied TCLP results for Pb above 300 mg/L in this hotspot, which exceed the TCLP regulatory threshold in two orders of magnitude, while Cd (up to 0.8 mg/L) and Cr (up to 0.3 mg/L) results were below the respective TCLP thresholds. Surface soil profile analysis (0-30 cm depth) indicates that Pb vertical migration occurs in the hotspot. TCLP concentrations of Pb were up to four orders of magnitude higher than the groundwater quality threshold preconized by Brazilian regulations for this metal (0.01 mg/L), suggesting that downward dispersion of large loadings of anthropogenic Pb is a major concern.

RESUMEN La movilidad potencial de Cd, Cr, Cu, Ni, Pb y Zn en suelos gravemente afectados por el almacenamiento inadecuado de desechos industriales en el estado de Río de Janeiro, Brasil, se evaluó mediante la aplicación del procedimiento de lixiviación con características de toxicidad (TCLP, por sus siglas en inglés). Este procedimiento permitió la estimación de riesgos de toxicidad para Cd, Cr y Pb. En una zona de alta contaminación dentro del área de estudio, se observó el siguiente orden de concentraciones de metales: Pb > Zn > Cu > Ni > Cd > Cr, con valores significativamente más altos que los observados para un sitio de control. Décadas de exposición del suelo a desechos implicaron resultados de TCLP para Pb por encima de 300 mg/L en esta zona, los cuales exceden el umbral regulatorio de TCLP en dos órdenes de magnitud, mientras que los valores de Cd (hasta 0.8 mg/L) y Cr (hasta 0.3 mg/L) estuvieron por debajo de los umbrales de TCLP respectivos. El análisis del perfil del suelo superficial (0-30 cm de profundidad) indica que la migración vertical de Pb se produce en la zona de alta contaminación. Las concentraciones de Pb obtenidas con el TCLP fueron hasta cuatro órdenes de magnitud más altas que el umbral de calidad del agua subterránea recomendado por las regulaciones brasileñas para este metal (0.01 mg/L), lo que sugiere que la dispersión descendente de grandes cargas de Pb antrópico es un problema importante.

ABSTRACT Studies involving coastal sediment resuspension have shown that trace metals could be released to the water column due to changes in physical-chemical conditions. Therefore, if environmental agencies adopt screening protocols with insufficient evaluations of contaminant mobilization risks for a given area, the prediction of environmental impacts caused by dredging may be limited. This work evaluates the influence of spatial variation on the geochemical mobility of trace metals (Cd, Cu, Ni, Pb, Zn) after artificial sediment resuspension, using as study case the Iguaçu River estuary (Guanabara Bay, Brazil). The Iguaçu River drains the industrial complex of the metropolitan area of Rio de Janeiro State, besides the presence of agriculture and the input of untreated domestic wastes. Surface estuarine sediments were submitted to resuspension experiments in an open system, during 1h and 24h of agitation on local water. A clear tendency of metals’ solubilization was observed after resuspension, especially considering the dissolved concentrations of Cu (average: 8.0 µg L-1) and Zn (average: 0.9 mg L-1), especially for the samples from the transects 2 and 3. However, evaluations of water quality changes due to sediment resuspension are not requested by the legislation regulating the dredging activities. In the sediments, the results suggested a higher geochemical mobility of Cu, indicated by the massive increase on the bioavailable fraction after resuspension, mainly on the transect number 3, on the river’s mouth. The effects of resuspension were distinct between samples, suggesting that even in a small scale, important differences on metals’ mobility are found. Thus, the combined assessment of changes in metal concentrations in water and in the metal partitioning linked to the solid-phase was demonstrated to be a promising tool for predicting the environmental risks of dredging due to changes in the bioavailability of metals.

Resumen Se evaluó el efecto de la adición de metano en un carbonizado de carbón sometido a reacción con concentraciones de oxígeno bajas. Desde un punto de vista cinético, dicho efecto es determinando por la energía de activación (Ea) y por el factor preexponencial para diferentes concentraciones de oxígeno y mezclas de oxígeno y metano. Se preparó un carbonizado con un tamaño de partícula de 75 a 150 μm a partir de un carbón bituminoso altamente volátil, y se determinaron los parámetros cinéticos de la oxidación empleando el método termogravimétrico de velocidad máxima. Las variables evaluadas en la cinética de oxidación fueron la concentración de oxígeno (5, 8 y 21 %), y el efecto de la adición de metano en el medio de reacción (5, 10 y 14 % de metano mezclado con 5 % de oxígeno). Los resultados mostraron que la Ea disminuía al aumentar la concentración de oxígeno, en tanto que al agregar metano se observó un efecto promotor cuando este correspondía al 5 % de la mezcla total; sin embargo, cuando el porcentaje de metano aumentaba, la Ea también lo hacía debido a la rápida reacción del oxígeno con el metano en fase homogénea comparada con la reacción heterogénea del oxígeno con el carbonizado. La Ea obtenida con 5 % de oxígeno fue de 122,9 kJ/mol y con 21 %, de 90,69 kJ/mol; en presencia de metano al 5 % y 5 % de oxígeno, la Ea fue de 110,7 kJ/mol, y aumentó hasta 170,8 kJ/mol cuando el metano representaba el 14 % de la mezcla. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat.

Abstract In this work we evaluated the effect of adding methane during the oxidation process of a coal char with low oxygen concentration. We analyzed the effect from a kinetic point of view and we determined the activation energy (Ea) and the pre-exponential factor (A) with different oxygen concentrations and oxygen and methane mixtures. We used a coal char from a highly volatile bituminous coal with particle size of 75 to 150 μm; the kinetic parameters were determined by thermogravimetric method (TGA) with the high-velocity model; oxygen concentration variations were studied with 5, 8 and 21% of oxygen, as well as the effect of adding methane (5,10 and 14%) when oxidation occurred with 5% of oxygen. The results showed that the Ea decreased when oxygen concentration increased, and that adding 5% of methane to the total mixture enhanced the effect. Instead, when we increased the methane percentage, the Ea increased due to the rapid reaction of oxygen and methane in the homogeneous phase as compared with the heterogenous reaction of oxygen and coal char. With 5% oxygen the Ea value was 122.9 kJ/mol and with 21%, it was 90.69 kJ/mol; when methane was added at 5%, the Ea value was 110.7 kJ/mol, and it increased to 170.8 kJ/mol when there was 14% of methane in the mixture. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat.

Precise and accurate d66/64Zn data for environmental reference materials (RMs) including rocks, sediments, soils and plants are presented in order to improve the metrological traceability and analytical control of Zn isotope ratio determinations in future environmental studies. Previously developed ion exchange chromatography protocols were adjusted to enable faster sample throughput and instrumental mass bias processes were investigated. The improved chromatographic protocol yielded precise and quantitative recoveries (99 ± 7%, σ, n = 16), while the mass bias correction using Cu as external dopant provided precisions better than 0.02‰, 2σ, n = 7. Investigations into spectral and non-spectral interferences identified significant formation of Cr and Ti oxides and hydroxide ionic species. Analysis of six RMs (BHVO-2 basalt (USGS), BCR-2 basalt (USGS), AGV-2 andesite (USGS), 2709 San Joaquin soil (NIST), 1646a estuarine sediment (NIST) and 1573a tomato leaves (NIST)) showed good reproducibility (< 0.01‰, 2s, 5 ≤ n ≥ 1).

Un residuo mineral industrial, proveniente de la producción de sulfato de aluminio, se utilizó como precursor para la preparación de un catalizador de bajo costo, activo en reacciones de hidroconversión de dibenciléter, como compuesto modelo de las uniones C-O en el carbón, y de un carbón subbtituminoso colombiano. El residuo mineral y un óxido de hierro comercial (material de referencia) se sometieron a un proceso de sulfuración con el propósito de generar un sulfuro de hierro tipo pirrotita (Fe1-xS), el cual es la fase activa del hierro en reacciones de hidroconversión. Los sólidos se caracterizaron por difracción de rayos X, fluorescencia de rayos X, espectroscopía Raman y microscopía electrónica de barrido. Las pruebas de actividad catalítica, con el compuesto modelo y el carbón, se realizaron a 5 MPa H2, a temperaturas entre 240 °C y 400 °C y tiempos de reacción de 0,5 h y 1 h. Los resultados mostraron que el residuo mineral industrial fue más activo que el material de referencia y que presentó alta actividad hacia la ruptura de los enlaces C-O en el dibenciléter, siendo estos los enlaces responsables del ensamble de asfaltenos y preasfaltenos en la estructura molecular del carbón. Adicionalmente, la conversión del carbón incrementó significativamente en presencia del residuo mineral sulfurado alcanzando un valor de 83,9 %, valor 1,8 veces mayor que para la reacción sin catalizador, evidenciando el potencial del residuo mineral para ser usado como catalizador en la hidroconversión del carbón, debido a su buena actividad y bajo costo.

An industrial mineral waste produced in the aluminum sulphate industry was selected as a low cost catalyst precursor. This material has been active in dibenzylether hydroconversion, as a model compound of C-O linkages in coal. Besides, it was used in the hydroconversion of a colombian subbituminous coal. The mineral waste and a commercial iron oxide (as reference material) were sulfided in order to produce iron sulfide, pyrrhotite type (Fe1-xS), which is the active phase in hydroconversion reactions. The solids were characterized by X-ray fluorescence, X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Catalytic tests with the model compound and coal were carried out at 5 MPa of H2, temperatures between 240 °C and 400 °C and reaction times were 0.5 h or 1 h. The results showed a higher activity of the industrial mineral waste compared with the reference material in the dibenzylether C-O bond cleavage. These kind of bonds are responsible for asphalthenes and preasphalthenes assembly in the molecular coal structure. In addition, coal conversion in presence of catalysts was 83.9 %, this value was 1.8 times higher than conversion without catalyst. Results show the potential of the industrial mineral waste to be used as catalyst in the hydroconversion of coal due to its good activity and low cost.

Resumo Objetivo: Existem poucos estudos que tratam dos processos que ocorrem em pequenos estuários que recebem uma elevada carga de matéria orgânica em regiões tropicais. O objetivo do presente trabalho foi caracterizar o comportamento biogeoquímico de nutrientes presentes em água superficial da foz do rio Iguaçu, durante condições específicas (maré de quadratura, vazante), localizado no setor interno de uma baía altamente eutrofizada (baía de Guanabara, SE Brasil). Métodos Variáveis físicas e químicas foram medidas in situ (pH, temperatura, condutividade, salinidade, total de sólidos dissolvidos, transparência, oxigênio dissolvido), já o material particulado em suspensão, clorofila a e os nutrientes (carbono e as formas de nitrogênio e fósforo) foram medidos em laboratório, ao longo de um gradiente estuarino mesohalino. Resultados A foz do rio Iguaçu está em alto estágio de eutrofização, considerando-se as concentrações de nutrientes, clorofila a e de transparência da coluna d' água encontrados. Os resultados indicam uma transição de condições heterotróficas para autotróficas, visto que as concentrações dos nutrientes diminuíram ao longo do gradiente salino, enquanto a clorofila a aumentou ao longo dos transecções. O pH e a razão clorofila : feopigmentos estiveram relacionados com a quantidade e qualidade da matéria orgânica em decomposição, sobretudo nos transecções sob maior influência marinha. Mais de 95% do nitrogênio dissolvido estava na forma de amônio (NH4+), proveniente do processo de amonificação da matéria orgânica em excesso na região, indicando presença de esgoto sem tratamento. Conclusão Neste estudo, o rio Iguaçu contribuiu com altas cargas de nutrientes que suportam uma importante produção primária na região interna da baía, estando relacionada à absorção de CO2 e metabolismo autotrófico, mostrando a importância de se identificar os comportamentos biogeoquímicos de nutrientes em áreas estuarinas, mesmo em pequena escala.

Abstract Aim: There are few studies dealing with the biogeochemical processes occurring in small estuaries receiving high sewage loading in tropical regions. The aim of this investigation was to characterize the biogeochemical behavior of nutrients in superficial waters collected at the Iguaçu estuarine system, during specific conditions (neap tide), located at the inner sector of a heavily eutrophicated embayment (Guanabara Bay, SE Brazil). Methods Physical and chemical variables were measured in situ (pH, temperature, conductivity, salinity, total dissolved solids, transparency, dissolved oxygen), whereas suspended particulate matter, chlorophyll a, phaepigments and nutrients (carbon, nitrogen and phosphorus forms) were measured in laboratory across the mesohaline estuarine gradient. Results The Iguaçu River mouth is in a high stage of eutrophication, considering nutrient concentrations, chlorophyll a and transparency of water column. Results indicate a transition from heterotrophic conditions to autotrophic conditions, since the nutrients concentrations showed a decreasing pattern along the saline gradient, while the chlorophyll an increased over the transects. The pH values and chlorophyll : phaeopigments ratios are significantly related to the amount and quality of organic matter contents, especially at transects under strong marine influence. More than 95% of the dissolved and total nitrogen concentrations are represented by NH4+ contributions, which are related to the ammonification of organic matter contents in this region, indicating the existence of untreated sewage loads in this area. Conclusion In this study, the Iguaçu River seemed to contribute with high inputs of nutrients that support important phytoplankton production at the inner regions of the bay related to the CO2 sink and autotrophic metabolism, showing the importance of verifying the biogeochemical behaviors of nutrients in estuarine areas, even in small scale.

Influência de drenagem ácida sobre a qualidade de água e sedimento foi investigada em uma área de mineração de carvão (sul do Brasil). A drenagem ácida mostrou pH entre 3,2 e 4,6 e elevadas concentrações de sulfato, As e metais, dos quais, Fe, Mn e Zn excederam os limites para emissão de efluentes da legislação brasileira. Arsênio também excedeu levemente o limite. Poços de monitoramento de água subterrânea situados em áreas de mina ativa e pilhas de rejeitos revelaram intervalo de pH e concentrações químicas semelhantes aqueles da drenagem ácida. Entretanto, amostras de águas subterrânea e de rio utilizadas para o abastecimento público municipal revelaram pH entre 7,2 e 7,5 e baixas concentrações químicas, embora a concentração de Cd tenha superado um pouco o limite adotado pela legislação brasileira para águas subterrâneas. Em geral, as águas de superfície mostraram grande intervalo de pH (6 a 10,8), e a influência da drenagem ácida em sua composição química não foi muito significativa. Localmente, drenagem ácida parece ter dissolvido rochas carbonáticas presentes na sequência estratigráfica local, atenuando a dispersão de metais e As. Anomalias destes elementos foram encontradas em sedimentos de corrente, e elas foram fortemente dependentes da proximidade de depósitos de rejeitos e minas abandonadas. Neste trabalho, processos de precipitação em sedimentos e diluição de fases dissolvidas foram considerados como os principais mecanismos responsáveis pela atenuação das concentrações de metais e As nas zonas de mistura entre drenagem ácida e água fluvial. Em geral, observou-se uma maior influência das atividades de mineração sobre a composição química de águas superficiais e sedimentos quando fatores de enriquecimento em relação aos níveis de background regionais foram utilizados.

Acid drainage influence on the water and sediment quality was investigated in a coal mining area (southern Brazil). Mine drainage showed pH between 3.2 and 4.6 and elevated concentrations of sulfate, As and metals, of which, Fe, Mn and Zn exceeded the limits for the emission of effluents stated in the Brazilian legislation. Arsenic also exceeded the limit, but only slightly. Groundwater monitoring wells from active mines and tailings piles showed pH interval and chemical concentrations similar to those of mine drainage. However, the river and ground water samples of municipal public water supplies revealed a pH range from 7.2 to 7.5 and low chemical concentrations, although Cd concentration slightly exceeded the limit adopted by Brazilian legislation for groundwater. In general, surface waters showed large pH range (6 to 10.8), and changes caused by acid drainage in the chemical composition of these waters were not very significant. Locally, acid drainage seemed to have dissolved carbonate rocks present in the local stratigraphic sequence, attenuating the dispersion of metals and As. Stream sediments presented anomalies of these elements, which were strongly dependent on the proximity of tailings piles and abandoned mines. We found that precipitation processes in sediments and the dilution of dissolved phases were responsible for the attenuation of the concentrations of the metals and As in the acid drainage and river water mixing zone. In general, a larger influence of mining activities on the chemical composition of the surface waters and sediments was observed when enrichment factors in relation to regional background levels were used.

Objetivo: Comparar resultados clínicos emtrabalhadores braçais submetidos à artrodese transforaminal aberta (TLIF) e minimamente invasiva (MIS-TLIF). Métodos: Setenta e oito pacientes foram submetidos à artrodese lombar pela mesma dupla de cirurgiões de coluna, de janeiro de 2008 a dezembro de 2012, sendo 41 artrodeses por cirurgia aberta tradicional e 37 por procedimento minimamente invasivo. Três pacientes não foram incluídos na pesquisa por já estarem aposentados. As variáveis analisadas foram: tempo de internação, tempo de seguimento, via de acesso (TLIF ou MIS-TLIF), necessidade de hemotransfusão, porcentagem de melhora ou piora após cirurgia, escala visual analógica (EVA) no pré e pós-operatório, tempo para retornar ao trabalho após a cirurgia, questionário Oswestry no pré-operatório e pós-operatório, além de aspectos gerais do trabalhador braçal como: idade, escolaridade, profissão, tempo de trabalho, peso que carrega diariamente no trabalho, uso ou não de equipamento de proteção individual (EPI). Resultados: O tempo de retorno ao trabalho foi maior no grupo de TLIF (média de 9,84 meses) em comparação ao grupo de MIS-TLIF (média de 3,20 meses). Houve melhora significativa da EVA e do questionário Oswestry no pós-operatório em ambos os grupos. O tempo de internação hospitalar médio foi de 5,73 dias para a TLIF e de 2,76 dias para o MIS-TLIF. Conclusões: A artrodese transforaminal minimamente invasiva apresenta resultados similares à da TLIF aberta, com os benefícios adicionais de menor morbidade pós-operatória, menor período de internação e reabilitação precoce em pacientes trabalhadores braçais.

Objective: To compare clinical outcomes in laborers who have undergone open transforaminal interbody fusion (TLIF) and minimally invasive transforaminal interbody fusion (MIS TLIF). Methods: 78 patients were submitted to lumbar arthrodesis by the same two spine surgeons partners from January 2008 to December 2012. Forty-one were submitted to traditional open arthrodesis and 37 to the minimally invasive procedure. Three patients were not included because they had already retired from work. The analyzed variables were length of hospitalization, length of follow-up, type of access (TILF or MIS TLIF), need for blood transfusion, percentage of improvement or worsening after surgery, pre- and postoperative VAS scale, time off work, pre-and postoperative Oswestry disability index, and general aspects of the laborers such as age, education, profession, working time, amount of daily weight carried at work, and use or not of personal protective equipment. Results: Time off work was longer in the TLIF group (average of 9.84 months) compared with the MIS TLIF group (average of 3.20 months). Significant improvement in postoperative VAS and Oswestry was achieved in both groups. Average length of hospitalization was 5.73 days for the TLIF group and 2.76 days for the MIS TLIF group. Conclusions: Minimally invasive transforaminal lumbar interbody fusion presents similar results when compared to open TLIF, but has the benefits of less postoperative morbidity, shorter hospitalization times, and faster rehabilitation in laborer patients.

Objetivo: Comparar los resultados clínicos en obreros sometidos a artrodesis transforaminal abierta (TLIF) y cirugía mínimamente invasiva (MIS-TLIF). Métodos: Setenta y ocho pacientes fueron sometidos a artrodesis lumbar por el mismo par de cirujanos de columna entre enero de 2008 y diciembre de 2012, siendo 41 artrodesis por cirugía abierta tradicional y 37 procedimientos mínimamente invasivos. Tres pacientes no se incluyeron en el estudio debido a que ya están jubilados. Las variables analizadas fueron la duración de la estancia hospitalaria, el tiempo de seguimiento, vía de acceso (TLIF o MIS-TLIF), necesidad de transfusión de sangre, el porcentaje de mejoría o empeoramiento después de la cirugía, la escala VAS (escala analógica visual) en el pre y postoperatorio, tiempo para volver al trabajo después de la cirugía, el cuestionario Oswestry pre y postoperatorio, además de los aspectos generales del trabajador como la edad, educación, profesión, tiempo de trabajo, la carga de peso diario en el trabajo, uso o no de equipo de protección personal (EPP). Resultados: El tiempo de retorno al trabajo fue mayor en el grupo TLIF (media de 9,84 meses) en comparación con el grupo MIS-TLIF (media 3,20 meses). Se observó mejoría significativa en VAS y el cuestionario Oswestry en el postoperatorio en ambos grupos. La estancia hospitalaria media fue de 5,73 días para TLIF y 2,76 días para MIS-TLIF. Conclusiones: La fusión transforaminal mínimamente invasiva muestra resultados similares a la TLIF abierta, con los beneficios añadidos de menor morbilidad postoperatoria, menor estancia hospitalaria y rehabilitación temprana de los obreros.

A composição geoquímica das águas intersticiais de sedimentos foi estudada em comparação com a composição das partículas sedimentares e de águas superficiais em um estuário de uma das áreas mais industrializadas da América Latina (sistema estuarino de Santos-Cubatão, sudeste do Brasil). Águas intersticiais e superficiais apresentaram altos níveis de F-, NH4+, Fe, Mn e P, devido a duas fontes industriais pontuais. No verão, quando as razões SO4(2-)/Cl- sugeriram aumento na redução do sulfato, os níveis mais elevados de alguns metais dissolvidos nas águas intersticiais (como Cu e Ni) foram atribuídos à dissolução redutiva de fases oxidadas. Os resultados sugerem que os riscos de aumento nas concentrações das águas superficiais por difusão ou advecção das águas intersticiais provavelmente dependem de influências conjuntas do aporte de águas de maré e águas subterrâneas.

The geochemical composition of sediment pore water was investigated in comparison with the composition of sediment particles and surface water in an estuary within one of the most industrialized areas in Latin America (Santos-Cubatão estuarine system, SE Brazil). Pore and surface waters presented anomalously high levels of F-, NH4+, Fe, Mn and P due to two industrial point sources. In the summer, when SO4(2-)/Cl- ratios suggested an enhanced sulfate reduction, the higher dissolved levels observed in pore waters for some metals (e.g., Cu and Ni) were attributed to reductive dissolution of oxidized phases. Results evidenced that the risks of surface water concentration increase due to diffusion or advection from pore water are probably dependent on coupled influences of tidal pumping and groundwater inputs.

The aim of this review is to take a look at Cold War era nuclear tests signatures found in Brazilian coastal sediments. Both137Cs and 240+239Pu signatures have been documented in mangrove, coastal mudflats and continental shelf sediments, associated with above ground nuclear tests beginning in the 1950's. The dates associated to the anthropogenic radionuclide signatures 137Cs and 240+239Pu along sediment columns are confirmed by 210Pb geochronology in many of the studies highlighted in this review. The results outlined in this review characterize the extent to which nuclear fallout products reach the Brazilian coast in quantities sufficient for detection, allowing the use of these radioisotopes as geochronometers.

The study of pyrolysis is gaining increasing importance, since it is the first step in the gasification or combustion process. In this study, pyrolysis experiments of cypress pine were carried out in a thermogravimetric analyzer at six different heating rates between 5 and 40 ºC / min. Kinetics parameters of pine were determined from TGA by using the differential and the maximum speed methods. Additionally, the distribution of activation energies was also carried out finding the values of 113.57 and 157.32 kJ/mol, which are in the range of activation energies reported for hemicellulose and cellulose, respectively, main components of wood.

A acumulação de Hg foi investigada em testemunhos sedimentares da Baía de Guanabara, Rio de Janeiro, Brasil, amostrados ao longo de um gradiente de eutrofização, que se refletiu na qualidade física dos sedimentos e na distribuição de carbono orgânico total (COT). Sedimentos da área oeste da baía foram fortemente afetados por aportes de efluentes domésticos e industriais, apresentando concentrações de Hg de até 7500 ng g-1 e inventários de Hg de até 786 mg m-2, em contraste com valores próximos aos de background encontrados na área nordeste (< 65 ng g-1 e 10,6 mg m-2). Uma mudança de uma relação negativa para uma positiva entre Hg e COT ocorreu no estuário mais eutrofizado, no qual um aumento nos níveis de Hg no sentido do topo foi observado. Este aumento pode ser atribuído a (i) um crescente aporte fluvial de Hg e (ii) um impacto da eutrofização sobre a qualidade dos sedimentos, que pode aumentar a sua capacidade de acumular Hg associado à matéria orgânica.

The accumulation of Hg was investigated in sediment cores from Guanabara Bay, Rio de Janeiro, Brazil, sampled along an eutrophication gradient, which was reflected in the sediment physical quality and total organic carbon (TOC) distribution. Sediments from the western bay area are strongly affected by inputs of urban and industrial effluents, showing Hg concentrations up to 7500 ng g-1 and Hg inventories up to 786 mg m-2, in contrast with near-background values found in the northwestern bay area (< 65 ng g-1 and 10.6 mg m-2). A shift from a negative to a positive relationship between Hg and TOC occurred in the most eutrophicated estuary, in which an upward increase in the recorded Hg levels was observed. This increase may be attributed to (i) an increasing riverine Hg input and (ii) an impact of eutrophication on the sediment quality, which may enhance the sediment capacity to accumulate organic matter-bound Hg.

Este trabalho registra pela primeira vez o histórico da contaminação e as fontes de 38 elementos em sedimentos do sistema estuarino de Santos-Cubatão (SE do Brasil), em uma das áreas mais industrializadas da América Latina. A composição de um testemunho de 260 cm de profundidade do estuário do rio Morrão foi determinada por ICP-MS e avaliada por meio de fatores de enriquecimento, análise de componentes principais, matrizes de correlação e assinaturas geoquímicas. Elementos contaminantes como Cr, Mn, Ni, Zn, Ga, Ag, Cd, Sn, Sb, Pb e Bi foram associados ao Fe, derivados de atividades siderúrgicas, enquanto Be, Ca, Sc, Co, Cu, Sr, Y, Zr, Nb, Hf, Ta, Th e U estiveram associados ao P, relacionados ao processo produtivo de fertilizantes. Uma sobreposição da distribuição do Fe sedimentar e produção local de aço indicaram que o Fe é um marcador confiável do histórico da contaminação, permitindo a estimativa de taxas de sedimentação para 45 anos de atividades industriais.

This paper records for the first time the contamination history and identifies the sources of 38 elements in sediments from the Santos-Cubatão Estuarine System (SE Brazil), at one of the most industrialized areas in Latin America. The compositions of samples from a 260 cm long sediment core collected in the Morrão River estuary were determined by ICP-MS. Enrichment factors, principal component analysis, correlation matrixes, and the characterization of geochemical signatures permitted a consistent data evaluation. Contaminant elements such as Cr, Mn, Ni, Zn, Ga, Ag, Cd, Sn, Sb, Pb, and Bi were associated with steel plant-derived Fe concentrations, while Be, Ca, Sc, Co, Cu, Sr, Y, Zr, Nb, Hf, Ta, Th, and U were associated with fertilizer industry-derived P concentrations. An overlap of sedimentary Fe distribution and local steel plant production indicated that Fe is a reliable marker of the contamination history, allowing the estimation of sedimentation rates over a period of 45 years of industrial activities.