Detection and analysis of arsenic-bearing particles in atmospheric dust using mineral liberation analysis

A new method was developed for the detection and analysis of arsenic-bearing particles in atmospheric dust using Mineral Liberation Analysis. This method, originally developed for metallurgical and geological samples, was modified for the analysis of atmospheric dust and is suitable for TSP and PMlow-volume air samples. Arsenic-bearing particles with an average diameter as small as 1 micrometer can be detected and measured with an analytical throughput of over 10,000 particles per hour. The method provides single particle data on particle size, morphology, elemental composition and mineralogy, and is suitable for both crystalline and non-crystalline phases. The first application of this method to a Brazilian mining town confirmed that the arsenic detected in air is not associated to arsenic-bearing mineral phases excavated at the mine site. This new technique provides crucial data on the source, distribution and potential toxicity of arsenic-bearing atmospheric particles in urban, rural and mining environments

Water availability, water quality water governance: the future ahead

The major challenge for achieving a sustainable future for water resources and water security is the integration of water availability, water quality and water governance. Water is unevenly distributed on Planet Earth and these disparities are cause of several economic, ecological and social differences in the societies of many countries and regions. As a consequence of human misuse, growth of urbanization and soil degradation, water quality is deteriorating continuously. Key components for the maintenance of water quantity and water quality are the vegetation cover of watersheds, reduction of the demand and new water governance that includes integrated management, predictive evaluation of impacts, and ecosystem services. Future research needs are discussed

Health risk assessment of arsenic in a residential area adjoining to a gold mine in Brazil

Paracatu is a town adjoining to a gold mine in Minas Gerais, Brazil where we collected drinking water and soil/dust samples were collected from seven residential locations. Fifteen common food categories were also collected from local vendors and stores. Arsenic was analysed by ICP-MS. A physiologically based extraction test for bioaccessibility (BAc) of arsenic was conducted on the soil/dust samples. Water arsenic ranged from non-detected to 3.9 μg/L; soil arsenic 6-461 mg/kg in th

A new method for arsenic analysis in Atmospheric Particulate Matter

Conventional methods for the analysis of arsenic in atmospheric particulate matter provide only bulk concentrations in different particle size fractions. We have developed a method that combines traditional gravimetric and bulk elemental ICP-MS analysis with automated SEM characterization of individual particles. By using this method, it is possible to establish which mineral phases (and non-crystalline matter) and which particle size fractions contribute to the total arsenic content in the atmospheric particulate matter. A less labor-intensive alternative method is currently being trialed using Mineral Liberation Analysis (MLA). Results of the first pilot study carried out in the Paracatu area (Minas Gerais, Brazil), where gold mineralization is associated with arsenopyrite, show that at this specific mine site atmospheric arsenic is primarily associated with organic combustion residues of forest fires, and not with the dispersion of arsenopyrite from the local mine site as previously postulated. This method can be applied in principle to trace the source of any element in atmospheric particulate matter, and can therefore be used to identify and manage activities and sources responsible for the release of potentially toxic elements into the atmosphere

Determination of arsenic in food from a Brazilian dietary survey

A food survey was conducted focusing on most commonly consumed staple dietary items obtained from local markets of three different towns in the State of Minas Gerais, Brazil. The samples were analyzed for total arsenic. The daily intake was estimated based on a Brazilian food consumption statistics and compared with the recommendation of international organizations. The data represent national samplings; the analyses were carried out by laboratories approved in inter-laboratory evaluations. Rice and beans alone contribute to approximately 90% of the total As intake from food. The calculated daily intake (0.399 μg/kg of body weight per day) is below the BMDL of 3.0 μg kg of body weight per day

A novel device for testing the mechanical behavior of metal electrodeposits during cathode stripping

The effect of the morphology and the crystallographic texture on the mechanical behavior of zinc electrodeposits is described. The mechanical behavior was assessed with a customized bending device and correlated to the main features of the deposit. The methodology proposed in this paper allows a better assessment of the effect of impurities (organics/inorganics) or additives on the quality of metal deposits, thereby assisting industry to optimize conditions and increase productivity. Bending tests carried out up to a bending angle of 50° revealed that the organic contaminants affect the mechanical properties of the zinc deposit differently. These properties were found to be strongly correlated to the electrodeposit's features. Highly porous deposits showed low ductility, which in turn caused the fracture of the sample at small bending angles, thus impeding effective stripping. The results obtained from the bending tests allowed a semi-quantitative prediction for the behavior of different zinc deposits during the stripping operation.Fil: Majuste, D.. Universidade Federal de Minas Gerais; BrasilFil: de Castro Bubani, Franco. Universidade Federal de Minas Gerais; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martins, E. L. C.. No especifíca;Fil: Cetlin, P. R.. Universidade Federal de Minas Gerais; BrasilFil: Ciminelli, V. S. T.. Universidade Federal de Minas Gerais; Brasi

Arsenic entrapment by nanocrystals of Al-magnetite: The role of Al in crystal growth and As retention

The nature of As-Al-Fe co-precipitates aged for 120 days are investigated in detail by High Resolution Transmission Electron Microscopy (HRTEM), Scanning TEM (STEM), electron diffraction, Energy Dispersive X-Ray Spectroscopy (EDS), Electron Energy-Loss Spectroscopy (EELS), and Energy Filtered Transmission Electron Microscopy (EFTEM). The Al present in magnetite is shown to favour As incorporation (up to 1.10 wt%) relative to Al-free magnetite and Al-goethite, but As uptake by Al-magnetite decreases with increasing Al substitution (3.53-11.37 mol% Al). Arsenic-bearing magnetite and goethite mesocrystals (MCs) are formed by oriented aggregation (OA) of primary nanoparticles (NPs). Well-crystalline magnetite likely formed by Otswald ripening was predominant in the Al-free system. The As content in Al-goethite MCs (having approximately 13% substituted Al) was close to the EDS detection limit (0.1 wt% As), but was below detection in Al-goethites with 23.00-32.19 mol% Al. Our results show for the first time the capacity of Al-magnetite to incorporate more As than Al-free magnetite, and the role of Al in favouring OA-based crystal growth under the experimental conditions, and therefore As retention in the formed MCs. The proposed mechanism of As incorporation involves adsorption of As onto the newly formed NPs. Arsenic is then trapped in the MCs as they grow by self-assembly OA upon attachment of the NPs. We conclude that Al may diffuse to the crystal faces with high surface energy to reduce the total energy of the system during the attachment events, thus favouring the oriented aggregation