Contaminação por mercúrio no Brasil: fontes industriais vs garimpo de ouro

This paper reviews the history of Hg contamination in Brazil by characterizing and quantifying two major sources of Hg emissions to the environment: industrial sources and gold mining. Industry was responsible for nearly 100% of total Hg emissions from the late 1940's to the early 1970's, when efficient control policies were enforced, leading to a decrease in emissions. Gold mining, on the other hand was nearly insignificant as a Hg source up to the late 1970's, but presently is responsible for over 80% of total emissions. Presently, over 115 tons of Hg are released into the atmosphere in Brazil annually. Nearly 78 tons come from gold mining operations, 12 tons come from chlor-alkali industry and 25 tons come from all other industrial uses. Inputs to soils and waters however, are still unknown, due to lack of detailed data base. However, emissions from diffuse sources rather than well studied classical industrial sources are probably responsible for the major inputs of mercury to these compartments.

Havia alguma ciência no Brasil setecentista?

In the past decade several articles have been published in this journal and elsewhere by different authors, dealing with the institutionalization of science in Brazil, its origins and subsequent history. The emphasis has often been directed to the work of Brazilian scientists working abroad, to foreigners in Brazil, or to a few private individuals within the country, as well as to cultural, social, economic and political considerations. Much of the attention has also been focused on "academic" science, rather than on empirical or technical developments. The present article presents some of these situations, particularly in the mining district, where the application of technology, sometimes quite up-to-date for the time, tended to blur somewhat the distinction between science and its applications. It is hoped that this may start a debate which will enrich our historiography in this field and be of interest to those who want to assess Brazil's position in the history of science.

Les Sentències catòliques del diví poeta Dant (1545) d’en Jaume Ferrer de Blanes: edició crítica del text

Procurador reial i nobiliari, cosmògraf, joier, lapidari, mercader i escriptor, i al capdavall, un ciutadà català honrat, en Ferrer (Vidreres, ~1445 – Blanes, 1529) va marxar de ben jove, primer, a la cort de Nàpols, al servei del rei en Ferran I, i després a la cort de Sicília, al servei de la reina na Joana de Sicília. Acabada aquesta peripècia italiana va tornar a Blanes al servei del vescomte de Cabrera i de Bas fins que va morir a la mateixa vila al 1529. Un seu criat, disset anys més tard, va editar uns papers esparsos que havia trobat a can Ferrer, les (sic) Sentèncias cathòlicas del diví poeta Dant florentí, compilades per lo prudentíssim mossèn Jaume Ferrer de Blanes, incloent-hi tres parts. La primera, Conclusions, és un sumari destinat a mostrar (sic) «Entre totas las cosas necessàries a l’home per aconseguir lo seu fi y beatitut eterna principalment són tres»; la segona, Meditació, és una reflexió a fi d’il•luminar els misteris sobre la passió i mort de Jesucrist a (sic) «lo santíssim loch de Calvari»; la tercera, Letras, és un conjunt de dotze documents, entre cartes i d’altres textos, «fetas a mossèn Jaume Ferrer, respostes e regles per ell ordenades en cosmographia y en art de navegar». En Ferrer, home de grans recursos, fa un recorregut per tots els coneixements que havia acumulat al llarg de la seva vida, de Dant Alighieri a Ptolemeu i del marquès de Santillana a Albert Gran o a Aristòtil, fent servir fragments de la Commedia, dels Proverbios, de la Bíblia i de moltes altres autoritats científiques i filosòfiques, en català, italià, espanyol, llatí i, també, set mots en arameu

Aplicação de técnicas eletroquímicas no estudo da dissolução oxidativa da covelita (CuS) por Thiobacillus ferrooxidans

Among the copper sulphides, chalcopyrite (CuFeS2), covellite (CuS) and chalcocite (Cu2S) are the most important source of minerals for copper mining industry. The acknowledge of behaviour of these sulphides related with bacterial leaching process are essential for optimization procedures. Despite of its importance, covellite has not deserved much interest of researchers regarding this matter. In this work it was studied the oxidation of covellite by the chemolithotrophic bacterium Thiobacillus ferrooxidans by using electrochemical techniques, such as open circuit potentials with the time and cyclic voltammetry. The experiments were carried out in acid medium (pH 1.8), containing or not Fe2+ as additional energy source, and in different periods of incubation; chemical controls were run in parallel. The results showed that a sulphur layer is formed spontaneously due the acid attack, covering the sulphide in the initial phase of incubation, blocking the sulphide oxidation. However, the bacterium was capable to oxidize this sulphur layer. In the presence of Fe2+ as supplemental energy source, the corrosion process was facilitated, because ocurred an indirect oxidation of covellite by Fe3+, which was produced by T. ferrooxidans oxidation of the Fe2+ added in the medium.

Coagulação/floculação de suspensões ricas em óxidos de ferro por sulfato de alumínio

The destabilization mechanism of suspensions of positively charged iron oxide particles by aluminum sulphate was investigated, aiming to evaluate the efficiency of the latter as a coagulant for natural surface waters from iron ore mining plants. Synthetic waters that simulate natural suspensions were used. The best coagulant dosage was found to be 100 mg/L at pH 4. The specific adsorption of hydrolysis products of aluminum salts on iron oxide particles and heterocoagulation processes involving differently charged substrates are proposed to explain the turbidity reduction of the suspensions.

Adsorção de As, Cu, Pb e Cr na avaliação da capacidade de fixação de metais por resíduo de mineradoras de ferro

Two samples of residues from iron mining plants have been investigated for their retention capacity of As, Cu, Cr, and Pb. The sample with the higher content of iron oxides showed the highest capacity to retain metals. The adsorption affinity series changes from Pb>Cu>Cr~As to As>Pb>Cu>Cr or As>Cu>Cr>Pb, depending on the material and the concentration of the initial solution. In the competitive environment, the Pb adsorption decreases and the As, Cu and Cr adsorption increases. Sequential extraction procedures, carried out after adsorption batch experiments, showed that the most important adsorption process occurs in the oxide fraction and that the major part of the absorbed metal is remobilized from exchangeable and oxide fractions.

Educational Data Mining: cerrando el círculo del proceso de aprendizaje en entornos virtuales

Development of methods to explore data from educational settings, to understand better the learning process.

A importância do observatório de atividades industriais vis-à-vis tendências em ciência, tecnologia e inovação

Given that innovation is fundamental for competitiveness, and that it is intrinsically linked to knowledge, it has become essential to foster effective interaction between the Brazilian productive sector and universities and R&D centers. This interface should be created by means of the model used in developed countries: Observatory of Industrial Activities and Trends in Science, Technology and Innovation. The present work describes its main functions, using examples of activities undertaken by the Chemical Industry Information System of the Federal University of Rio de Janeiro related to production systems of primary and high-tech industries, examining the diffusion of knowledge to decision-makers.

Microesferas de quitosana reticuladas com tripolifosfato utilizadas para remoção da acidez, ferro(III) e manganês(II) de águas contaminadas pela mineração de carvão

Considerable attention has been paid to chitosan and derivatives as efficient adsorbents of pollutants such as metal ions and dyes in aqueous medium. Nevertheless, no report can be found on the remedial actions of chitosan microspheres crosslinked with tripolyphosphate to control acidity, iron (III) and manganese (II) contents in wastewaters from coal mining. In this work, chitosan microspheres crosslinked with tripolyphosphate were used for the neutralization of acidity and removal of Fe (III) and Mn (II) from coal mining wastewaters. The study involved static and dinamic methods. The neutralization capacity of the surface of the static system was 395 mmol of H3O+ per kilogram of microspheres, higher than that of the dynamic one (223 mmol kg-1). The removal of Fe(III) in wastewater was of 100% and that of Mn(II) was 90%.

Avaliação do teor de metais em sedimento do rio Betari no Parque Estadual Turístico do Alto Ribeira: PETAR, São Paulo, Brasil

The subsoil of the Vale do Ribeira was the focus of mining industries for the exploration of lead, mainly inside the park - PETAR. Despite the fact that the exploration has ended, the environmental effects of those activities are still present, due to great amounts of heavy metals that are leached. Concentrations of pseudo-total and bioavailable metals were determined in sediment samples of the Betari River, using atomic absorption spectrometry. The results demonstrated that the sediments are contaminated by Pb, Zn and Cu. The findings can contribute to an efficient and environmentally and economically adequate management of the park, for the conservation and the protection of the area.

Data mining and mall users profile

Marketing scholars have suggested a need for more empirical research on consumer response to malls, in order to have a better understanding of the variables that explain the behavior of the consumers. The segmentation methodology CHAID (Chi-square automatic interaction detection) was used in order to identify the profiles of consumers with regard to their activities at malls, on the basis of socio-demographic variables and behavioral variables (how and with whom they go to the malls). A sample of 790 subjects answered an online questionnaire. The CHAID analysis of the results was used to identify the profiles of consumers with regard to their activities at malls. In the set of variables analyzed the transport used in order to go shopping and the frequency of visits to centers are the main predictors of behavior in malls. The results provide guidelines for the development of effective strategies to attract consumers to malls and retain them there.