Over a century of mining activities and smelting in the area of Sudbury, Ontario, Canada have resulted in the contamination of the local soils with metal(loid) bearing particulates. Minor and trace elements associated with these phases are released during their weathering. This release is therefore strongly dependent on the mineralogical and chemical character of the metal(loid) bearing phases. The metal(loid)s are then subject to transport before being attenuated through their incorporation into secondary phases. Elevated concentrations of metal(loid)s in silica rich alteration layers has recently been described for altered surfaces at the solid-water and solid-atmospheric interfaces in tailings, and in the vicinity of smelters, respectively. To determine if similar coatings occur in soils, samples were taken from areas around three major smelting centers in the area. Coated grains were extracted from these samples and individually mounted to be analysed. Particulate matter (representing primary metal(loid)-bearing phases) and coatings (secondary metal(loid)-bearing phases) were analysed using scanning electron microscopy, Raman spectroscopy, Laser-Ablation Inductively-coupled plasma mass spectroscopy, Micro-X-ray fluorescence, and X-ray photoelectron spectroscopy. The particulates were divided into three main groups: smelter-derived particles, sulfides, and nickel-oxides. Smelter derived particles contained the most elevated concentrations of metal(loid)s in their sulfide inclusions and metal(loid)-rich rims. The mobility of metal(loid)s in the identified mineral phases found within particulates mirrored the transport observed in the soil column; Zn>Cu>Ni>Pb. Once mobilized, these elements are subject to transport before being attenuated by secondary phases. Micro-coatings were found to be composed of hematite, schwertmannite, ferrihydrite, silica, and jarosite group minerals. Coatings are distinguished on the basis of their atomic Si:Fe ratios: FeOx coatings have Si:Fe <1, Si–FeOx coatings have Si:Fe between 1-10, and SiOx coatings iv have Si:Fe>10. Iron-rich coatings (FeOx) and silica-rich coatings (SiOx) have lower trace-metal concentrations than Fe-SiOx coatings. Micrometer-thick coatings are predominantly composed of hematite, schwertmannite, ferrihydrite and (amorphous) silica and contain elevated metal(loid) concentrations in the form of metal(loid)-rich phosphate minerals (mainly minerals of the jarosite group). A general model is developed that describes the formation of mineral coatings in acid soils and their important role in the uptake and retention of metal(loids). Here, micrometer-thick Fe-silica coatings form through adsorption, co-precipitation and dehydration processes involving amorphous silica and iron hydroxides. Metal(loid)-bearing phases nucleate within a gel-type matrix and are subsequently preserved during dehydration and solidification. Aluminum-rich surfaces form on mineral grains once the pH has been raised sufficiently high (pH~5-6) so as to lead to the complete removal of sulfate-bearing phases. The implications of this model are widespread in terms of the attenuation of metal(loid)s in acid soils and their retention or subsequent remobilization in recovered soils with near neutral pH.

Made available in DSpace on 2016-03-15T19:21:58Z (GMT). No. of bitstreams: 1 Thalita Nayara da Cunha Pereira.pdf: 9322382 bytes, checksum: 1877e7c3f1f8f09c603e2fdc8b382f77 (MD5) Previous issue date: 2012-08-09 / The deployment of the industry in São Paulo city is a phenomenon that originated in the second half of the nineteenth century. The technological resources and production systems adopted in more than a century of industrialization has resulted in environmental damage only now being properly assessed. The contaminated place in the floodplains of Tamanduateí river and along the railways - reflects the history of occupation of the territory of São Paulo. Thus, 41.31% of the 4131 areas currently diagnosed as contaminated by CETESB are located in the Metropolitan Region of São Paulo, especially the state capital, which holds approximately 31.17% - a third of the total. A great example of the consequence of the urban industrial expansion is Vila Carioca, Ipiranga s neighborhood, which was aggravated due to the Shell Company of Brazil, with small leaks over the years and careless operating practices, released contaminants in soil and groundwater, affecting neighboring land. The presence of environmental impacts is one aspect that has gained prominence in the discussions on models of change in urban centers. For urban areas previously occupied by industrial activities, it is necessary to develop specific public policy intervention. The recovery of attention to these areas is associated with the need for requalification of degraded urban areas and to curb the spreading irrational and irresponsible planning of cities, the consequences reflected in the economic, social, health and environment. Thus, it is essential to analysis and understanding how is the relationship between population and the urban environment, lifestyles, standards of production and consumption to assess and minimize risks.The implantation of the industry at São Paulo city is a phenomenon raised on the second half in the 19th century. The technologies sources and productions systems adopted in this period resulted in environmental liabilities that only now it has been correctly analyzed. / A implantação da indústria na cidade de São Paulo é um fenômeno que teve origem na segunda metade do século XIX. Os recursos tecnológicos e sistemas de produção adotados nesse mais de um século de industrialização resultaram em passivos ambientais que somente agora vêm sendo devidamente avaliados. A localização das áreas contaminadas nas várzeas do Rio Tamanduateí e ao longo das estradas de ferro reflete a história de ocupação do território paulista. Deste modo, 41,31% das 4.131 áreas atualmente diagnosticadas como contaminadas pela CETESB estão localizadas na Região Metropolitana de São Paulo, com destaque para a capital paulista, que concentra cerca de 31,17% um terço do total. Um grande exemplo da consequência dessa expansão da malha urbana e escalada industrial é a Vila Carioca, no bairro do Ipiranga, que teve como maior agravante em sua área a empresa Shell do Brasil que, com pequenos vazamentos ao longo dos anos e práticas operacionais pouco cuidadosas, lançou contaminantes no solo e águas subterrâneas, atingindo também terrenos vizinhos. A presença de impactos ambientais é um aspecto que vem ganhando relevância nas discussões sobre os modelos de alteração dos centros urbanos. Para as áreas urbanas anteriormente ocupadas por atividades industriais, faz-se necessário o desenvolvimento de políticas públicas específicas de intervenção. A retomada da atenção para essas áreas associa-se à necessidade de requalificação dos espaços urbanos degradados e da contenção do espraiamento irracional e sem planejamento responsável das cidades, cujas consequências refletem nos planos econômico, social, sanitário e ambiental. Desta forma, é imprescindível a análise e compreensão de como se dá a relação entre a população e o ambiente urbano, estilos de vida, padrões de produção e consumo para a avaliação e minimização de riscos.