Anthropogenic influences on Cd, Cr,Cu, Ni, Pb and Zn concentrations in soils and sediments in a watershed with sugar cane crops at São Paulo State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biosorption of cadmium (II) and lead (II) from aqueous solution using exopolysaccharide and biomass produced by Colletotrichum sp.

The biosorption of Cd(II) and Pb(II) ions on biomass and exopolysaccharide (EPS) produced by Colletotrichum sp. fungus has been investigated as a function of contact time, initial pH, initial metal ion concentration, and initial adsorbent concentration in a batch system. Adsorption equilibrium was described by Freundlich and Langmuir isotherms. Adsorption was characterized through granulometry, SEM and EDX analysis. Then, studies were performed to regenerate the adsorbent. Biosorption of metals by biomass and EPS were best described by the Langmuir and Freundlich isotherm, respectively. Results of thermodynamic investigations showed that adsorption reactions were spontaneous (ΔG° < 0), exothermal, and mainly physical. The EPS was able to remove 79 and 98% of cadmium and lead, respectively, and the biomass removed 85 and 84% of cadmium and lead, respectively, in a solution with initial concentration 100 mg L-1, and the four adsorption-desorption cycles of all adsorbents showed up with great regenerative capacity and relative stability after these four cycles, the high potential of these biological materials in sorption has been shown. © 2013 Copyright Balaban Desalination Publications.

Sr-Nd-Pb isotopic constraints on the nature of the mantle sources involved in the genesis of the high-Ti tholeiites from northern Paraná Continental Flood Basalts (Brazil)

There has been little research on geochemistry and isotopic compositions in tholeiites of the Northern region from the Paraná Continental Flood Basalts (PCFB), one of the largest continental provinces of the world. In order to examine the mantle sources involved in the high-Ti (Pitanga and Paranapanema) basalt genesis, we studied Sr, Nd, and Pb isotopic systematics, and major, minor and incompatible trace element abundances. The REE patterns of the investigated samples (Pitanga and Paranapanema magma type) are similar (parallel to) to those of Island Arc Basalts' REE patterns. The high-Ti basalts investigated in this study have initial (133Ma) 87Sr/86Sr ratios of 0.70538-0.70642, 143Nd/144Nd of 0.51233-0.51218, 206Pb/204Pb of 17.74-18.25, 207Pb/204Pb of 15.51-15.57, and 208Pb/204Pb of 38.18-38.45. These isotopic compositions do not display any correlation with Nb/Th, Nb/La or P2O5/K2O ratios, which also reflect that these rocks were not significantly affected by low-pressure crustal contamination. The incompatible trace element ratios and Sr-Nd-Pb isotopic compositions of the PCFB tholeiites are different to those found in Tristan da Cunha ocean island rocks, showing that this plume did not play a substantial role in the PCFB genesis. This interpretation is corroborated by previously published osmium isotopic data (initial γOs values range from+1.0 to+2.0 for high-Ti basalts), which also preclude basalt generation by melting of ancient subcontinental lithospheric mantle. The geochemical composition of the northern PCFB may be explained through the involvement of fluids and/or small volume melts related to metasomatic processes. In this context, we propose that the source of these magmas is a mixture of sublithospheric peridotite veined and/or interlayered with mafic components (e.g., pyroxenites or eclogites). The sublithospheric mantle (dominating the osmium isotopic compositions) was very probably enriched by fluids and/or magmas related to the Neoproterozoic subduction processes. This sublithospheric mantle region may have been frozen and coupled to the base of the Parana basin lithospheric plate above which the Paleozoic subsidence and subsequent Early Cretaceous magmatism occurred. © 2013 Elsevier Ltd.

Síntese de perovskitas nanométricas com estrutura 'PB IND.1-x''M IND.X''TI''O IND.3'(M='BA', 'CA' e 'SR')

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação do potencial de compostos naturais (argila, turfa e carvão) na remoção do Chumbo (Pb) e da toxicidade de um efluente industrial

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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

ABSTRACT: 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/²⁰⁷ ratios (1.172 < ²⁰⁶Pb/²⁰⁷ < 1.188) point to an anthropogenic lead contribution, originated by the industrial and urban activities of the city of Belem.

Uranium-lead dating method at the Pará-Iso isotope geology laboratory, UFPA, Belém – Brazil

ABSTRACT: Analytical procedures for U-Pb isotope dilution analyses at the Pará-Iso isotope geology laboratory of the Federal University of Pará (UFPA) are described in detail. The procedures are applied to zircon, titanite, rutile, apatite, columbite-tantalite and whole rock. Reagent preparation and chemical processing are done in clean-room conditions. Samples are dissolved using Teflon™ microcapsules in steel jacket Teflon™ Parr Instrument™ bomb or Teflon™ screw cap containers. U and Pb are separated using anion exchange AG 1x8 resin columns. Typical blanks for mineral sample amounts of 0.01 to 1.0 mg are less than 1 pg U and 20-30 pg Pb. Isotope analysis of the U and Pb from the same filament are carried out using a Finnigan MAT 262 mass-spectrometer in static and dynamic modes. The current analytical level is demonstrated on analyses of international standard zircon 91500 with three different ²³⁵U-²⁰⁵Pb and ²³⁵U-²⁰⁸Pb isotope tracers and whole rock standards. Results of analyses of two zircon samples are also presented.

U-Pb SHRIMP and 40Ar/39Ar constraints on the timing of mineralization in the Paleoproterozoic Caxias orogenic gold deposit, São Luís cratonic fragment, Brazil

Caxias é um depósito de ouro orogênico do fragmento cratônico São Luís, que é correlacionável aos terrenos Riacianos do Cráton Oeste-Africano. O depósito se formou após o metamorfismo regional (estimado em 2100 ± 15 Ma) e está hospedado em zona de cisalhamento que secciona xistos do Grupo Aurizona (2240 ± 5 Ma) e o Microtonalito Caxias. O microtonalito foi aqui datado em 2009 ± 11 Ma, e representa um estágio magmático tardio na evolução do fragmento cratônico São Luís. Cristais de zircão com idades de 2139 ± 10 Ma foram herdados da fonte magmática ou são produto de contaminação durante a intrusão. A composição dos isótopos de chumbo sugere que granitoides de arco de ilhas de ca. 2160 Ma são a fonte provável para o Pb incorporado na pirita relacionada com o minério. Sericita hidrotermal mostra idade ⁴⁰Ar/³⁹Ar de 1990 ± 30 Ma, que, combinada com a idade de posicionamento do microtonalito hospedeiro, limita o evento mineralizador ao intervalo 2020-1960 Ma.

Simple, Direct and Simultaneous Stripping Voltammetric Determination of Lead and Copper in Gasoline Using an In Situ Mercury Film Electrode

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Thermal and structural study of glasses in the binary system TeO2-Pb(PO3)(2)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bismuth as a general internal standard for lead in atomic absorption spectrometry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural, microstructural, optical and electrical properties of (Pb,Ba,Sr)TiO3 films growth on conductive LaNiO3-coated LaAO(3)(100) and Pt/Ti/SiO2/Si substrates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of lead in eye shadow and blush by high-resolution continuum source graphite furnace atomic absorption spectrometry employing directSolid sampling

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sodium nitrite prevents both reductions in circulating nitric oxide and hypertension in 7-day lead-treated rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Local structure around Fe ions on multiferroic Pb(Fe1/2Nb1/2)O-3 ceramics probed by x-ray absorption spectroscopy

Local structure around Fe ions on Pb(Fe1/2Nb1/2)O-3 ceramics was probed by x-ray absorption spectroscopy in order to settle the controversies about its structure. It is observed that the shell structure around Fe atoms exhibits a monoclinic local symmetry at 130 and 230 K, tetragonal local symmetry at room temperature, and cubic local symmetry at 410 K. Independently of the coordination, temperature, or symmetry, Fe-O mean bond-length does not vary significantly. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4709490]