Distribuição e especiação de mercúrio em sedimentos de áreas de garimpo de ouro do quadrilátero ferrífero (MG)

The concentration and thermodesorption speciation of mercury in sediments from four different Iron Quadrangle sites impacted by gold mining activity were determined. The mercury content of some samples was considerably high (ranging from 0.04 to 1.1 µg g-1). Only Hg2+ was found and it was preferably distributed in the silt/clay fraction in all samples. Cluster analysis showed that mercury and manganese can be associated. The occurrence of cinnabar in this region as another mercury source was also discussed, corroborating earlier works showing the importance of natural mercury in the geochemical cycle of the metal in this region.

Distribuição, fracionamento e mobilidade de elementos traço em sedimentos superficiais

The gold and iron mining activities in the Velhas River yield considerable amounts of suspended solids as well as metals to the hydrological system of the region. The risks were assessed by sequential extraction procedures. They were carried out in sediment samples, aiming to evaluate the presence of Co, Cr, Cu, Ni, Zn and As. Although being at high levels in some parts of the river (e.g. As 527 mg g-1 and Cr 475 mg g-1) they are associated with the residual fraction. Mobility factors were also calculated and show that these species are enriched along the river, e.g. for As 0.02 at the spring and 0.33 at the high course of the river.

Implantación de la ISO 14001 en una planta de tratamiento de vehículos fuera de uso (VFU)

Nos hemos propuesto implantar la ISO 14001 en un centro autorizado de tratamiento de vehículos fuera de uso, denominado Recycling Gandía, S.L., con el fin de que dicho centro pueda obtener una ventaja competitiva, respecto de otros centros ubicados próximamente, dada la fuerte competencia existente. Con la implantación de un Sistema de Gestión Medioambiental y más concretamente la ISO 14001, se puede conseguir una mejora de la imagen de la empresa, un ahorro de costes, se pueden mejorar las relaciones con la Administración e incluso con las entidades financieras, se puede contribuir a la motivación de los trabajadores, se asegura el cumplimiento de la legislación ambiental. La actividad que nos ocupa, se dedica a la recepción y descontaminación de vehículos al final de su vida útil, reutilizando piezas o componentes de recambio., Los objetivos del presente trabajo van a ser fundamentalmente, el implantar el Manual de Gestión Ambiental en la planta de tratamiento de vehículos fuera de uso y el describir todos los procedimientos genéricos a seguir. Como conclusiones de este trabajo, tendremos las auditorías con las no conformidades detectadas, así como el compromiso adquirido en todos los niveles y departamentos de la empresa, lo cual se traducirá en una mejor satisfacción de los clientes y por tanto un aumento en el número de vehículos a tratar.

Automatització d'una planta de processos químics

Resum L’any 1969 es van començar a comercialitzar els sistemes digitals programables coneguts com autòmats programables o PLC’s, utilitzats per controlar qualsevol tipus de procés industrial. Al llarg de tots aquests anys, aquests sistemes i tota la tecnologia en general han evolucionat molt, i només és qüestió de temps que la tecnologia que utilitzem avui en dia quedi obsoleta i substituïda per una de millors característiques i amb més avantatges. Aquest és el motiu de l’elaboració d’aquest treball, que com a objectiu pretén modernitzar un procés de fabricació d’una industria química que ha quedat molt limitat a causa de l’antiguitat de la instal•lació. Per dur a terme aquesta modernització, s’introdueixen sistemes de control amb majors prestacions, s’utilitzen xarxes de comunicacions per facilitar el muntatge elèctric de la instal•lació i un sistema de supervisió i adquisició de dades per poder obtenir un control més estricte del procés de fabricació i de tots els factors que intervenen. El funcionament del procés de fabricació és que a partir d’unes matèries primeres líquides emmagatzemades en dipòsits, es dosifiquin aquestes matèries en l’ordre i la quantitat desitjada dins un o diversos recipients per barrejar-les i aplicar els tractaments que siguin necessaris. Tot aquest procés està controlat per un autòmat programable, i disposa de diferents terminals operadors per poder interactuar amb el sistema. També té implementat un sistema SCADA en diversos ordinadors per aportar una visió general de la planta en temps real, un registre de dades dels paràmetres que es controlen i alhora serveix per enllaçar amb la xarxa d’ordinadors existent. Com annex d’aquest treball, es presenten els esquemes elèctrics i el programa de l’autòmat programable per veure totes les característiques elèctriques dels dispositius i el mètode de funcionament del procés. S’ha aconseguit donar un salt tecnològic i poder gaudir de tots els avantatges que ofereixen les noves tecnologies, que com a resultat s’ha optimitzat i millorat el procés de fabricació. De totes les conclusions, la més destacada és la d’haver dissenyat un sistema de control basat en una estructura descentralitzada molt flexible, que es pot expandir i adaptar fàcilment als possibles canvis.

Uma abordagem simplificada do método Monte Carlo Quântico: da solução de integrais ao problema da distribuição eletrônica

The paper presents an introductory and general discussion on the quantum Monte Carlo methods, some fundamental algorithms, concepts and applicability. In order to introduce the quantum Monte Carlo method, preliminary concepts associated with Monte Carlo techniques are discussed.

Alargamento da distribuição de massa molar de polímeros sintetizados com catalisadores metalocênicos dual-site

The main topics related to the use of dual-site catalysts in the production of polymers with broad molecular weight distribution are reviewed. The polymerization using dual-site catalysts is more economical and allows to produce a higher quality product than other processes, such as polymer blend and multistage reactors. However, the formulation of these catalysts is quite complicated since the same catalyst must produce distinct polymer grades. In addition, the release of patents concerning the combination of metallocenes and new technologies for polymerization shows that polymerization processes using dual-site catalysts are of current industrial interest.

Distribuição e biodisponibilidade de crômio em solos contaminados por resíduos de couro

Samples of soil, water and sediment were collected and analyzed in order to evaluate chromium contamination due to deposition of tannery residues onto soils under different management regimes. The results showed that soils used for sugar cane cultivation were not adversely impacted. However, in the case of mango plantations, variable concentrations of chromium were measured in the soil profile, with 22.2% of values being higher than permitted legal limits, and 38.9% being at levels requiring remediation. Concentrations of bioavailable chromium were lower than the detection limit of the method (0.01 mg of chromium kg-1 of soil), indicating that all of the chromium present in the samples was either complexed or in an insoluble form. Chromium concentrations measured in samples of water and sediments were indicative of low mobility of the metal in soils. The main cause of differences found between soil samples obtained from different cultivations was the type of soil management.

Avaliação do risco ambiental em sedimento dos lagos do Riacho Cambé, em Londrina, pela distribuição de metais

The proposal of this study was to obtain the profile of these metals distribution Al, Co, Cu, Pb, Cr, Ni, Co and Zn in sediments from lakes in the city of Londrina-PR and evaluate the environmental risk resulting from such distribution. The parameters of comparison were the values of geological occurrence of these metals in soil from this region, the concentrations of metals in soil samples in the surroundings of the sediments collection points, the guiding values from CETESB and resulting rate risk from RAC criterion application. The result shows that the numerical scale RAC alone is incomplete to this evaluation.

Caracterização do MP10 e MP2,5 e distribuição por tamanho de cloreto, nitrato e sulfato em atmosfera urbana e rural de Londrina

Samplings of atmospheric particulate matter (PM) were carried out between the months of March and April of 2007, simultaneously in two areas of Londrina, an urban (Historical Museum) and other rural (Farm School-UEL). PM was collected using the cascade impactor consisting of four impaction stages (0.25 to 10 μm). The results indicated that the fine fraction (PM2.5) represented a significant portion of the mass of PM10 (70 and 67% in the urban and rural places, respectively). Cl-, NO3- and SO4(2-) were determined by ion chromatography and the size distribution is presented. Natural and anthropogenic sources were suggested to the ionic components in the fine and coarse mode of PM.

Distribuição espacial de compostos orgânicos de estanho em sedimentos costeiros e em Phallusia nigra da Baía de Todos os Santos e litoral norte da Bahia - Brasil

Organic tin compounds were investigated in the sediment of twenty-four stations located in the Todos os Santos Bay and the north coast of Bahia - Brazil. The concentration of these organic tin was also determined in a ascidium species of Phallusia nigra. The speciation and quantification was performed by GC-MS/MS. The highest concentrations were: tributyltin (TBT) 438 ng g-1, dibutyltin (DBT) 207 ng g-1, monobutyltin (MBT) 423 ng g-1, diphenyltin (DPT) 25.8 ng g-1 and monophenyltin (MPT) 55.0 ng g-1. DBT and MBT were found in Phallusia nigra, with highest concentrations of 294.1 and 148.5 ng g-1, respectively.

Distribuição de Hg total e suas associações com diferentes suportes geoquímicos em sedimentos marinhos da margem continental brasileira: Bacia de Campos - Rio de Janeiro

Mercury distribution and geochemical support on the Continental Margin was evaluated at the Campos Basin, Rio de Janeiro state, Brazil. The average concentrations for all analyzed elements were, respectively, 20 ± 5 ng g-1 (Hg); 30 ± 14 mg g-1 (Al); 16 ± 6 mg g-1 (Fe), and 254 ± 83 µg g-1 (Mn). Silt and clay content, total carbonate and Hg, and organic carbon increased with depth. Finally, the relationship between Hg and silt clay showed significant positive correlation. Total Hg concentrations are the background level described primarily (~40 ng g-1).

Lipídios como indicadores de fontes e distribuição de matéria orgânica particulada em um complexo estuarino-lagunar tropical (Mundaú-Manguaba, AL)

Fatty acids, alcohols and sterols were considered as markers of the source and distribution of particulate organic matter during the dry season in the Mundaú-Manguaba estuarine-lagoon system, NE Brazil. Lipid composition showed an overwhelming influence of autochthonous sources of organic matter in all system´s compartments, including the probable occurrence of algal blooms in specific areas. On the other hand, contamination by sewage was restricted to Mundaú lagoon. This scenario differed from known conditions observed in the wet season, illustrating the usefulness of the lipid biomarker approach for the characterization of other complex and dynamic systems in the Brazilian coastal zone.

Fontes e distribuição de matéria orgânica sedimentar no complexo estuarino-lagunar de Mundaú-Manguaba/AL, utilizando esterois e alcoóis como indicadores

The origin of the sedimentary organic matter in the Mundaú-Manguaba estuarine system was evaluated through the distribution and composition of sterols, alcohols and ancillary data. The muddy sediments of the lagoons are enriched in organic matter, derived from a mixture of autochthonous and allochthonous inputs. Mundaú exhibited moderate contamination by sewage, with coprostanol concentration as high as 4.4 µg g-1. The channels are characterized by sand and organic matter-poor sediments. The sediments from some rivers in the drainage basin accumulated organic matter derived only from terrestrial vegetation. Stanol/sterol ratios evidenced the preferential diagenesis of the autochthonous fraction of organic matter.

Distribuição e assinatura isotópica de Pb em sedimentos de fundo da Foz do Rio Guamá e da Baía do Guajará (Belém - Pará)

Lead analyses in bottom sediments from the hydrographic system of Belem (Para) indicated low contents of this metal for the sediments from the Guama river, with no significant anthropogenic contribution. A concentration of 18.1 ± 1.5 mg kg-1 and 206Pb/207Pb isotopic signature of 1.196 ± 0.002 are assigned for Pb from natural sources. On the other hand, the significant increase of Pb contents in the sediments from the Guajará bay, together with the decrease of 206Pb/207Pb ratios (1.172 < 206Pb/207Pb < 1.188) point to an anthropogenic lead contribution, originated by the industrial and urban activities of the city of Belem.

Distribuição de Zn, Pb, Ni, Cu, Mn e Fe nas frações do sedimento superficial do Rio Cachoeira na região sul da Bahia, Brasil

The metal distribution in the surface sediment fractions of the Cachoeira River was evaluated based on the fractionation method using a five-step sequential extraction. The determination of metals was made by flame atomic absorption spectrophotometry (F AAS). Zn, Pb and Cu exhibit higher concentrations in the residual fraction of the sediment from sites that receive discharges from urban and industrial zones. High levels of Ni (60 ± 1 to 447 ± 9 µg L-1) were found in the river water, which may be detrimental to the "health" of rural communities that utilize the river water for domestic purposes without treatment.