Dust originating from dry lakes contributes harmful and toxic elements to downwind urban areas and mountain snowpack that is compounded by local contaminant inputs from anthropogenic sources. To evaluate dust contributions to an urban area from regional playas, we sampled playa dust sources, urban dust deposition, and snow dust deposition in central Utah, USA. Samples were analyzed for grain size, mineralogy, and chemistry. Bulk mineralogy between playa, urban, and snow dust samples was similar, with silicate, carbonate, and evaporite minerals. Grain size distribution between fine playa, urban, and snow dust particles was also similar. Elements found at high concentrations in playas include Li, Na, Mg, Ca, Sr, and U, and most other elements were found at higher concentrations in urban and snow deposition samples. Particularly enriched elements in dust deposition include Cu, Se, Ag, Cd, Sb, and La, which are sourced from industrial activity, mining, and vehicular emissions and wear. Based on results from mass balance modeling, a large majority of the dust mass deposited on the Wasatch Front is from playa sources. Urban and playa dust sources largely remain constant seasonally, although spikes in playa-associated element concentrations during a particular seasonal sample may indicate frequent and/or more intense dust events. Among the highly environmentally available elements B, Ca, Sr, and U, are Cd and Se, both of which present toxicity concerns for humans and environments. This is the first study describing heavy metal contamination and sources in Utah, USA.

Made available in DSpace on 2014-12-17T15:42:06Z (GMT). No. of bitstreams: 1 JoaoBAF_DISSERT.pdf: 2926590 bytes, checksum: 284a772c6dacfa2a7184d7f4569c6cab (MD5) Previous issue date: 2011-03-11 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Although there are many studies on urban dust contamination by heavy metals in developed countries, little attention has been paid to this type of study in developing countries, including Brazil. Therefore, a series of investigations were performed to provide signatures of heavy metals in urban dust and assess the potential sources in the city of Natal - RN-Brazil. The fraction of these sediments was studied to pass through a sieve of 63 micrometers. For the study analyzed two groups of samples, one collected in September 2009 at the end of the rainy season (9 samples) and one collected in January 2010 in the dry season (21 samples). So in all, thirty sediment samples were collected from the street. Then, in Fluorescence Spectrometry X-rays were determined major elements SiO2, Na2O, K2O, Al2O3, MgO, P2O5, Fe2O3, MnO, TiO2 and CaO, and trace Rb, Cr, Ni, Cu, Zn, Sr and Pb by an ICPOES was determined Zn, V, Na, K, Ni, Mn, Mg, P, Fe, Cr, Cu, Pb, Ba, Ca and Al from leaching HCl 0.5 mol L-1 . The results of the concentrations of elements show that the greater presence of these occurs in the dry season, except for Si which is higher in the rainy season. Analyses by geoaccumulation Index (IGEO) Enrichment Factor (EF), Contamination Factor (CF), analysis correlation and Hierarchical Cluster, confirm that Zn, Cu and Pb is anthropogenic character. Zinc may be derived from various sources related to motor vehicles or the road signs and street grids. The elements Na, K, Mg and Ca may be related to droplets suspended in air containing cations and anions present in seawater (salty), common in Christmas throughout the year, brought by winds SE-NW. The elements Na, Mg, Ca and K are the most abundant in seawater and were analyzed in this study. This indicates that the source of these additional elements detected by analyzing the contamination factor may be the very sea. Moreover, Ni, Fe, Cr and Ba can be either as a source of anthropogenic geog?nica. The source of Ca is different, because it comes in lime and paint (painting guides of buildings and streets) in construction materials, but may also be present in sediments in the fragments of shells or carbonate bioclasts common in the coastal area / Embora existam muitos estudos sobre a contamina??o de poeiras urbanas por metais pesados nos pa?ses desenvolvidos, pouca aten??o tem sido dada a este tipo de estudo nos pa?ses em desenvolvimento, incluindo o Brasil. Portanto, uma s?rie de investiga??es foram realizadas para fornecer assinaturas de metais pesados em poeiras urbanas e avaliar as fontes potenciais na cidade do Natal RN-Brasil. A fra??o estudada destes sedimentos foi a passante na peneira de 63 μm. Para o estudo foram analisados dois grupos de amostras, sendo um coletado no m?s de setembro de 2009 no final da esta??o chuvosa (9 amostras) e outro coletado no m?s de janeiro de 2010 no final da esta??o seca (21 amostras). Portanto ao todo, trinta amostras de sedimentos de rua foram coletadas. Em seguida, por Espectrometria de Fluoresc?ncia de raios X foram determinados os elementos maiores SiO2, Na2O, K2O, Al2O3, MgO, P2O5, Fe2O3, MnO, TiO2 e CaO e tra?os Rb, Cr, Ni, Cu, Zn, Sr e Pb. Pela t?cnica de ICP-OES foram determinados Zn, V, Na, K, Ni, Mn, Mg, P, Fe, Cr, Cu, Pb, Ca, Ba e Al a partir de lixivia??o a HCl 0,5 mol L-1. Os resultados das concentra??es dos elementos mostram que a maior presen?a desses ocorre na esta??o seca, com exce??o para o Si que ? maior na esta??o chuvosa. As an?lises por ?ndice de Geoacumula??o (IGeo), Fator de Enriquecimento (FE), Fator de Contamina??o (FC), an?lises de correla??o e agrupamentos, confirmam que Zn, Cu e Pb tem car?ter antropog?nico. O Zn pode ser proveniente de fontes diversas relacionados aos ve?culos automotores ou ?s placas de sinaliza??o e grades das ruas. Os elementos Na, K, Mg e Ca podem estar relacionados ?s got?culas de ar que cont?m em suspens?o os c?tions e ?nions presentes na ?gua do mar (maresia), comum em Natal durante todo o ano, trazida pelos ventos SE-NW. Os elementos Na, Mg, Ca e K s?o os mais abundantes na ?gua do mar e foram analisados no presente trabalho. Isto indica que a fonte adicional destes elementos detectada atrav?s da an?lise do fator de contamina??o pode ser a pr?pria maresia. Por outro lado, Ni, Fe, Cr e Ba podem ser tanto de origem antropog?nica como de origem geog?nica. A fonte do Ca ? diversa, pois este entra na cal e tintas (pintura de edifica??es e guias de ruas), nos materiais de constru??o civil, mas pode estar tamb?m presente nos sedimentos nos fragmentos de conchas ou bioclastos carbon?ticos comuns na ?rea litor?nea