Mestrado em Química Analítica Ambiental / MSc in Environmental Analytical Chemistry

Oxidation of sulfidic mine waste is of significant environmental concern due to the consequent formation of acid rock drainage (ARD), deteriorating the water quality of natural water systems. Iron (Fe) and sulfur (S) are two major redox elements involved in these reactions and typically the major redox-sensitive elements (whose solubility, speciation, and mobility are affected by pH and Eh) in water affected by ARD. Measurements of Fe and S species concentrations may reveal valuable information about geochemical processes in mine waste but are typically included when analyzing the chemical composition of ARD. In this study, robust and portable methods for the determination of Fe and S species concentrations in leachate water affected by sulfidic mine waste were tested and evaluated. The leachate water resulting from interaction with high-  and low-sulfide waste rock was collected from three leaching columns, each reflecting different geochemical environments that could occur during mine waste management: (1) fully oxidized conditions (reference column), (2) gradual oxygen depletion from atmospheric level to <1% (anoxic column), (3) treatment with alkaline industrial residual material (alkaline column). The leachate water was analyzed for its pH, Eh, electric conductivity (EC), and major and trace elements. UV-Vis spectrophotometric ferrozine method was tested and applied for Fe speciation and concentration analysis, allowing determination of Fe(II) and Fetot and further calculation of Fe(III) as a difference. The method was found to achieve accurate and reliable results. Turbidimetry was tested and evaluated for dissolved sulfate analysis, and even though the analytical precision was poorer, ca. ±20%, the method provides useful semi-quantitative estimations of dissolved sulfate concentrations. Both spectrophotometry and turbidimetry are easy to perform and utilizes robust, cheap and portable instrumentation. Leachate water from the high and low sulfide experiments had pH and Eh in the range of pH 2.6 – 12 and Eh 200 – 720 mV and pH 3.5 – 4 and Eh 550 – 700 mV, respectively. Measurements of iron species and sulfate concentrations revealed that sulfate was the dominating S species and during the background leachate Fe(II) was the predominant Fe oxidation state. Upon decreasing oxygen saturation and pH in the anoxic column, Fe speciation in the reference and anoxic column differed, with the relative importance of Fe(III) increasing in the anoxic column. Total Fe, pH and Eh potential measured in the leachate water did not respond to decreasing oxygen saturation, but changes in the Fe redox speciation coincided with this decrease. Under alkaline conditions, total Fe and sulfate concentrations decreased in the alkaline environment, indicating their immobilization in the solid phase. Geochemical calculations were carried out to gain further understanding of the dominant reactions in the columns. Theoretical values of Fe(II) and Fe(III) concentrations were calculated from the measured redox potential, and these were found to deviate from the measured concentrations. Therefore, estimation of Fe species distribution from redox measurements using a Pt-electrode is not considered sufficient in these systems. Mineral saturation indices of common secondary minerals associated with ARD indicated dissolution of ferrihydrite, jarosite and schwertmannite in the leachate water from the anoxic column. This suggests that these minerals are the probable source of the Fe and sulfate, as well as As and Cu released to the leachate water.

A região metropolitana de São Paulo apresenta um intenso e desordenado processo de urbanização e industrialização. Devido a estes processos, a região sofre grandes problemas de poluição atmosférica, agravados em certos meses devido às dificuldades de dispersão dos poluentes. Estes poluentes causam efeitos indesejáveis ao meio ambiente e à saúde humana. A caracterização química e a avaliação da atividade mutagênica desses compostos presentes no material particulado atmosférico (MPA) é um grande desafio analítico e, é de extrema importância para o conhecimento das possíveis correlações entre os poluentes, os efeitos deletérios à saude e as fontes de emissão. Os objetivos deste trabalho foram caracterizar quimicamente os extratos orgânicos polares e semi-polares do material particulado atmosférico da cidade de São Paulo e avaliar sua atividade mutagênica. O MPA é uma mistura complexa de compostos orgânicos e inorgânicos presentes em diferentes faixas de concentrações. Devido a esta complexidade, o fracionamento químico do extrato orgânico deste material é necessário para isolar classes de compostos ou compostos individuais, permitindo a identificação e quantificação dos mesmos. Os resultados obtidos pelas diversas técnicas analíticas empregadas mostraram que os extratos em diclorometano e acetona contém inúmeros compostos orgânicos pertencentes a diferentes classes, tais como hidrocarbonetos policíclicos aromáticos, quinolinas, cetonas, piridinas, furanos, aldeídos, amidas e aminas, sendo que alguns destes compostos são considerados agentes genotóxicos. O extrato em DCM contem a maior massa e sua composição é quase exclusivamente orgânica. Já o extrato em ACE contem além dos orgânicos, espécies inorgânicas. Testes de mutagenicidade indicaram que o MPA coletado na cidade de São Paulo apresenta uma atividade mutagênica relativamente alta quando comparada a outros centros urbanos. / São Paulo metropolitan area presents an intense and chaotic process of urbanization and industrialization. Due to this processes, this region has big atmospheric pollution problem. In certain months of the year, this problem gets worse due to the unfavorable dispersion conditions. The pollutants cause undesirable effects to the environment and to the human health. The chemical characterization and the mutagenic activity evaluation of the compounds present on the atmospheric particulate matter APM) represents an analytical challenge and it is very important for understanding of the correlation among pollutants, health hazards and emission sources. The goal of this work was chemically characterize the polar and moderately polar organic extracts from the APM collected in São Paulo city and to evaluate their mutagenic activity. The APM is a complex mixture of organic and inorganic compounds present in large range of concentration. Due to this complexity, the chemical fractionation of these organic extracts is necessary to isolate classes or individual compounds, to allow their identification and quantification. The results obtained using different analytical techniques demonstrated that the dichlorometane and acetone extracts has several organic compounds belonging to different classes, such as, polycyclic aromatic hydrocarbons, quinolines, ketones, pyridines, furanes, aldehydes, amides and amines. Some of these compoundsa are considered carcinogens and/or mutagens. The dichloromethane extract presented the highest mass yield and its composition is almost exclusively organic. The acetone extract has organic and inorganic species. Mutagenicity tests revealed that the APM from São Paulo city presented a have relatively high mutagenic activity when compared to other urban regions.

A região metropolitana de São Paulo apresenta um intenso e desordenado processo de urbanização e industrialização. Devido a estes processos, a região sofre grandes problemas de poluição atmosférica, agravados em certos meses devido às dificuldades de dispersão dos poluentes. Estes poluentes causam efeitos indesejáveis ao meio ambiente e à saúde humana. A caracterização química e a avaliação da atividade mutagênica desses compostos presentes no material particulado atmosférico (MPA) é um grande desafio analítico e, é de extrema importância para o conhecimento das possíveis correlações entre os poluentes, os efeitos deletérios à saude e as fontes de emissão. Os objetivos deste trabalho foram caracterizar quimicamente os extratos orgânicos polares e semi-polares do material particulado atmosférico da cidade de São Paulo e avaliar sua atividade mutagênica. O MPA é uma mistura complexa de compostos orgânicos e inorgânicos presentes em diferentes faixas de concentrações. Devido a esta complexidade, o fracionamento químico do extrato orgânico deste material é necessário para isolar classes de compostos ou compostos individuais, permitindo a identificação e quantificação dos mesmos. Os resultados obtidos pelas diversas técnicas analíticas empregadas mostraram que os extratos em diclorometano e acetona contém inúmeros compostos orgânicos pertencentes a diferentes classes, tais como hidrocarbonetos policíclicos aromáticos, quinolinas, cetonas, piridinas, furanos, aldeídos, amidas e aminas, sendo que alguns destes compostos são considerados agentes genotóxicos. O extrato em DCM contem a maior massa e sua composição é quase exclusivamente orgânica. Já o extrato em ACE contem além dos orgânicos, espécies inorgânicas. Testes de mutagenicidade indicaram que o MPA coletado na cidade de São Paulo apresenta uma atividade mutagênica relativamente alta quando comparada a outros centros urbanos. / São Paulo metropolitan area presents an intense and chaotic process of urbanization and industrialization. Due to this processes, this region has big atmospheric pollution problem. In certain months of the year, this problem gets worse due to the unfavorable dispersion conditions. The pollutants cause undesirable effects to the environment and to the human health. The chemical characterization and the mutagenic activity evaluation of the compounds present on the atmospheric particulate matter APM) represents an analytical challenge and it is very important for understanding of the correlation among pollutants, health hazards and emission sources. The goal of this work was chemically characterize the polar and moderately polar organic extracts from the APM collected in São Paulo city and to evaluate their mutagenic activity. The APM is a complex mixture of organic and inorganic compounds present in large range of concentration. Due to this complexity, the chemical fractionation of these organic extracts is necessary to isolate classes or individual compounds, to allow their identification and quantification. The results obtained using different analytical techniques demonstrated that the dichlorometane and acetone extracts has several organic compounds belonging to different classes, such as, polycyclic aromatic hydrocarbons, quinolines, ketones, pyridines, furanes, aldehydes, amides and amines. Some of these compoundsa are considered carcinogens and/or mutagens. The dichloromethane extract presented the highest mass yield and its composition is almost exclusively organic. The acetone extract has organic and inorganic species. Mutagenicity tests revealed that the APM from São Paulo city presented a have relatively high mutagenic activity when compared to other urban regions.