This research project investigated the high concentration of sulphate in a tailing pond at LKAB and the characteristics and behavior of sulphate minerals in different areas of the pond. The sampling of the tailings was carried out at Nine stationary sampling points. Each sample was taken from the surface to a depth of one meter except for the underflow sample which was collected from the thickener in the processing plant (fresh tailings). Stereo microscopy and SEM-EDS analysis aid in identifying mineral grains and confirming the presence of Gypsum and/or Anhydrite, along with other minerals like Pyrite, Pyrrhotite, and Chalcopyrite. The difficulty in distinguishing between Gypsum and Anhydrite under SEM was noted due to their similar crystal shapes and chemical composition. Gypsum and/or Anhydrite were identified as the main minerals responsible for the high sulphate concentration based on elemental screening, sequential extraction, and mineralogical results. Sulfide minerals like Pyrite, Chalcopyrite, and Pyrrhotite were also present but did not show any signs of weathering characteristics and therefore probably not contributed to the high sulphate concentration in the pond. The quantitative mineralogy carried out confirmed the presence of Gypsum and/or Anhydrite, Pyrite, Pyrrhotite and Chalcopyrite as identified in the mineralogical analysis. The study concludes that Gypsum and/or Anhydrite are the main contributors to the high sulphate concentration in the LKAB tailings pond.

Rare earth elements are the 14 lanthanides on the periodic table, plus yttrium and scandium. These elements play a critical role in modern-day technologies such as liquid-crystal displays, GPS systems, and fiber optic cables. A majority of the mining of these elements is from China; however, due to decreasing reserves a need for alternative processes for extracting and processing rare earth elements (REEs) is becoming increasingly important. Special focus has been placed upon the identification of REEs within coal refuse, but the phase designation and speciation is not fully understood. This investigation focuses on the characterization, speciation, and morphology of REEs within fine and coarse coal refuse. During this study, physical and chemical characterization was conducted on coal refuse samples to understand characteristics, which influence REE phase designation. Experimental methods were chosen to specifically evaluate REE content and speciation across four key characteristics: size distribution, density, seam location, and thermal decomposition. Characterization of the refuse material was conducted in two campaigns: (1) an exploratory campaign, which focused on size distribution, and physical imaging of REEs within fine refuse, and (2) a detailed campaign, which utilized sequential chemical extraction methods alongside calcination to understand the phases in which REEs are present in coarse refuse. The results show that REEs within fine coal refuse are smaller than ten microns and found with phosphorus. In general, as size decreased REE content increased, likely due to increased clay content. Further conclusion could not be drawn from simple microscopic analysis. Consequently, detailed chemical characterization was conducted to fully understand REE speciation. The tests showed that a majority of REEs within coarse refuse were within insoluble species. A calcination treatment was found to greatly increase the recovery of REEs from the metal oxide fraction, thus increasing the overall soluble species contained within the coarse refuse material. / Master of Science / Due to increasing global demand and limited reserves, alternative sources for rare earth elements (REEs) have become an increasingly important research topic. REEs are a vital component of many modern technologies, including GPS systems, fiber optic cables, and LCD screens. Current mining of REEs is primarily from Chinese reserves which are becoming increasing depleted and are not strictly regulated for environmental impact. Due to these challenges, other resources of REEs are of increasing importance. Prior research has found coal and associated byproducts to have concentrations of REEs that could be economically exploited, reducing the rate of depletion of REE resources worldwide. To develop more efficient and cost-effective processing methods, fundamental information on the mineral composition of REE-bearing materials is needed. With this information, engineers can develop better processes that can specifically target REE-containing minerals while maximizing economic and environmental outcomes. This research seeks to overcome this knowledge gap through advanced material characterization and well-controlled laboratory process testing of coal refuse. The results show that REEs typically congregate in specific material fractions (e.g. fine size, moderate density), and these materials can be readily transformed through simple heat treatment. This transformation greatly improves the processability and provides a pathway for the economic recovery of REEs from coal wastes. The further development and deployment of these technologies can have societal benefits such as: more jobs, reduced reliance on foreign sources, and environmental cleanup of current coal waste deposits.

The mobility of arsenic is controlled by the mineral source of arsenic and a host of biogeochemical factors such as pH, oxidation-reduction reactions, precipitation-dissolution reactions, adsorption-desorption processes, and the activity of microorganisms. In this study, sequential extraction and microscopic methods were used to evaluate arsenic partitioning in different phases in sediments and host rock at the Brinton arsenic mine (BAM) site. Results demonstrate spatial variability of arsenic in sediments, although the partitioning of arsenic in different phases was similar in both mine tailing and stream channel sediments. The sequential extraction results demonstrate that between 60 and 80 % of the total arsenic in sediments is associated with iron oxides, and an additional phosphate extraction showed that the majority (80%) of arsenic associated with the oxides is adsorbed. Imaging and analysis by scanning electron microscopy (SEM) and electron microprobe analysis (EMPA) show the presence of three arsenic bearing minerals, arsenopyrite, scorodite and arsenic-rich iron oxides, in both sediment and the host rock. In sediment, the minerals are present as individual grains, but in the host rock, they are present together, often with arsenopyrite at the core, surrounded by scorodite and/or elemental sulfur, which is rimmed by iron oxides. This spatial arrangement illustrates two weathering patterns of arsenopyrite, one that involves oxidation to form scorodite, which further dissolves to form arsenic-rich iron oxides; in this weathering series, sulfur presumably forms dissolved species which migrate away from the mineral. Another pattern, observed in several samples of host rock, involves formation of elemental sulfur in addition to scorodite and iron oxides. Results of this study have implications for arsenic mobility at the Brinton site and other mine sites where arsenic minerals are present. Although arsenopyrite is the main ore mineral, the main reservoir of arsenic in sediments is iron oxides. However, in the end it is the biogeochemical mechanism that releases arsenic from the mineral that will control arsenic mobility. In the case of iron oxides, desorption or reductive dissolution will promote arsenic release, whereas oxidizing conditions are required for arsenopyrite to release arsenic. / Master of Science

Os ambientes estuarinos, interface entre oceano e o continente, são classificados como um dos mais importantes ecossistemas existentes, tanto pela sua localização na quanto pela sua importância para as espécies locais e outras tantas espécies dependentes desse habitat. Elementos como o Ferro e Enxofre desempenham importante papel nesses ambientes, devido principalmente às condições anóxicas impostas pela constante inundação. Tais elementos são peças-chave para diversos processos biogeoquímicos relacionados metais, e a oxidação da matéria orgânica em ambiente redutor, e os processos geoquímicos relacionados a estes elementos variam com a dinâmica de marés, a presença de organismos e plantas. Embora seja evidente a importância de estuários, ainda não existem muitas medidas efetivas que previnam as descargas de poluentes diretamente nessas áreas, como metais pesados; que podem estar presentes em grandes quantidades no esgoto urbano e industrial. Além disso, metais podem ser liberados em casos isolados, como por exemplo, no rompimento da barragem da Samarco em 2015 liberando grande quantidade de rejeitos de processamento de minérios. Nesse sentido este trabalho teve como objetivo, avaliar os efeitos da chegada do rejeito à Foz do Rio Doce no Estado do Espírito Santo, no comportamento geoquímico dos elementos Fe, Mn, Zn e Cu no ambiente estuarino. Foram coletadas amostras de solo e do rejeito depositado, ao longo do estuário do Rio Doce, nas proximidades do município de Regência (coordenadas 19º 24\' 20\" S e 40º 4\' 5\" W ), no nordeste do Estado do Espírito Santo. Em campo foram medidos os valores de pH e Eh e em laboratório determinado as frações de metais através de extrações sequenciais e a determinação do teor de MO e composição granulométrica. Também foi feito análise de DRX no rejeito, pelo método de amostra em pó seca o qual demonstra óxidos de ferro como hematita e goethita. Os resultados mostram grande variação de Eh e pH, predomínio da fração areia no solo, e teores de MO em média entre 2,67±2,31 e 6,28±3,51%. Os teores de metais como o Fe, Mn, Cu e Zn apresentaram-se consideravelmente elevados, devido principalmente, a composição do rejeito e fortemente associados às formas óxidos e pouco Fe e metais associados à fração pirítica, o que expõe o risco de biodisponibilidade de metais pela redução do Fe. / The estuarine environments, an interface between ocean and the continent lands are classified as one of the most important ecosystems existing, as much for its location as for its importance for the local species and other species dependent on that specific habitat. Elements such as iron and sulfur play an important role in these environments, mainly due to the anoxic conditions imposed by frequent flooding. These elements are key pieces for several biogeochemical processes related to metals, and the oxidation of organic matter in reducing environment, and the geochemical processes related to these elements vary with the dynamics of tides, the presence of organisms and plants. Although the importance of estuaries is evident, there are still many effective measures to prevent the discharge of pollutants directly into these areas, such as heavy metals; Which may be present in large quantities in urban and industrial sewage. Additionally, metals can be released in isolated cases, for example, in the colapse of the Samarco´s dam in 2015 releasing large amounts of ore processing tailings. Thus, the objective of this work was to evaluate the effects of the arrival of the tailings to Rio Doce river, in the state of Espírito Santo, in the meaning of geochemical behavior of the elements Fe, Mn, Zn and Cu in the estuarine environment. Soil and deposited tailings were sampled and collected along the Rio Doce estuary near the city of Regência (coordinates 19º 24 \'20 \"S and 40º 4\' 5\" W), in the northeast of the State of Espírito Santo. The values of pH and Eh were measured on field, and in laboratory were determined the fractions of metals through sequential extractions as well the determination of the content of MO and granulometric composition. XRD analysis was also carried out in the tailings by the dry powder sample method, which demonstrates iron oxides such as hematite and goethite. The results showed a great variation of Eh and pH, predominance of the sand fraction in the soil, and OM levels between 2.67 ± 2.31 and 6.28 ± 3.51%. The metals, such as Fe, Mn, Cu and Zn, were considerably elevated, mainly due to the composition of the waste and strongly associated with the oxides and low Fe and metals associated with the pyritic fraction, which exposes the risk of bioavailability of Metals by the reduction of Fe.

Phosphorus release from sediments contributes significantly to high phosphorus level in lake water and provides nutrient support to promote algal growth. To speed up the recovery of eutrophic lakes, it is necessary to limit phosphorus release from sediments. Accurate sedimentary phosphorus fractionation is a strong basis for understanding phosphorus release from sediments. There are several techniques to study sedimentary phosphorus fractionation. Chemical sequential extraction (CSE) techniques are commonly used by industrial practitioners. However, it is doubtful that the P fractionation of the lake sediments studied using the Jensen and Thamdrup (1993) method is reliable. The reason is that the phosphorus fractions do not exactly correspond to the chemically defined compounds in the sequential phosphorus extraction. In order to further understand the Jensen and Thamdrup (1993) method, it is necessary to study P species in the supernatant and residue of each fraction. X-ray absorption near-edge structure (XANES) can provide direct information about the mineral phase of phosphorus in the sediments. Solution phosphorus nuclear magnetic resonance (31P NMR) reveals direct molecular and structural characterization of organic phosphorus in the sediments. This study enhanced the understanding of the Jensen and Thamdrup (1993) chemical sequential extraction method for studying the sedimentary phosphorus fractionation by using solution 31P NMR spectroscopy and phosphorus K-edge XANES spectroscopy. The research using the chemical sequential extraction indicated that inorganic P was dominant in all sediments samples. Also, it suggested that calcium-bound P accounted for the largest proportion of the total P in every sediments sample. The solution 31P NMR spectroscopy clearly identified orthophosphate, phytic acid, pyrophosphate, and polyphosphate in the sediments samples. The P K-edge XANES spectroscopy showed all of the sediments samples contained apatite and phytic acid. In addition, the study using the XANES identified apatite in the residue after the HCl extraction of Blackstrap #6; however it indicated no apatite in the supernatant of HCl fraction of both Blackstrap #3 and Pond #11.

Coal is a combustible sedimentary rock composed of a complex heterogeneous mixture of mostly organic constituents and minor inorganic phases. Coal is a vital energy resource providing more than half of the electric power generated in the United States. However, coal combustion is responsible for a significant portion of anthropogenic release of different toxic elements including sulfur into the environment. Therefore, deciphering the residence of the different fractions of sulfur in coal is essential. In this study, eight different sulfur fractions from Pennsylvanian-age coal samples collected from the Murphysboro, Mount Rorah, Springfield (No. 5), and Herrin (No. 6) coal seams from the Illinois Basin were separated using a wet sequential chemical extraction procedure in order to evaluate the coal quality and to test the efficiency of this technique. The average weight percent of sulfur in each seam was 1.98%, 2.1%, 2.26%, and 2.4%, respectively, showing that the coal samples were of medium-sulfur-type. Among the eight different sulfur fractions extracted, kerogen sulfur was found to be the most abundant, followed by sulfate sulfur, fulvic acid sulfur, pyritic sulfur, and elemental sulfur. However, XRD and coal petrography revealed the significant amounts of pyrite still present in the coal sample even after pyritic sulfur extraction, indicating that the finely disseminated pyrite in the coal was not completely removed during the sequential extraction. The sulfur isotopic study showed the average δ34S values of pyritic sulfur and sulfate sulfur in the Murphysboro coals as 7.82 / and 2.44 / and that of Mount Rorah coals were 10.68 / and 7.87 /, respectively. The heavier δ34S values of pyritic sulfur compared to the sulfate sulfur can be explained by a bacterial sulfate reduction (BSR) model in a closed system where most of the sulfate reservoir was consumed at the top of the seam. Similarly, the average δ34S values of elemental sulfur for the same coals (8.05 / and 14.54 /, respectively) were also heavier than the sulfate sulfur which suggests the pyrite oxidation followed by disproportionation of intermediate sulfur species. The δ34S values of handpicked pyrite samples and the mercury concentration for the Herrin (No.6) and Springfield (No. 5) coals indicated at least two stages of hydrothermal inputs into these coal seams. SEM/EDS and petrographic microscopy of the Illinois coal samples revealed the presence of different syngenetic and epigenetic sulfur-containing minerals such as framboidal pyrite, euhedral pyrite, galena, anhydrite, anglesite, and also non-sulfur containing minerals such as calcite and clay. Based on these results, it can be said that sulfur in Illinois coals is present in different phases extractable by wet sequential chemical extraction however; care should be taken during each individual extraction step to obtain better results.

Orientador: Edson Luiz Mendes Coutinho / Banca: Mara Cristina Pessoa da Cruz / Banca: Takashi Muraoka / Abstract: A greenhouse experiment was carried out to evaluate the effects in soil, plant and soybean dry matter yield in function of manganese rates and sources. The distribution of manganese in different fractions was evaluated. A completely randomized design in a factorial arrangement 3x6x3 (soil x rate x Mn source) was used. The soils were classified as Typic Quartzipsamment (soil 1), clayey Typic Haplustox (soil 2) and sandy clay loam Typic Haplustox (soil 3). Mn rates were 0, 5, 10, 20, 40 e 60 mg kg-1 using single superphosphate + Mn (micronutrient incorporated in ordinary superphosphate granulation), "Fritted" Mn and manganese sulphate. The available Mn was determined with Mehlich-1 (M-1) and DTPA. The extractants used to evaluate Mn solubility in fertilizers were: water, 20 g L-1 citric acid and neutral ammonium citrate solutions. The agronomic effectiveness of the manganese sources was calculated using manganese sulphate as reference. Using sequential extraction, the soil Mn was partitioned into exchangeable, organic, amorphous Fe and Al oxides, crystalline Fe and Al oxides and residual forms. Mn fertilization increased Mn content in soybean shoot, regardless to soil and source considered. Dry matter yield depended of Mn initial in soils. In soils 1 and 2, which had low Mn content, occured an increase in soybean dry matter yield. The DTPA and M-1 extractants were efficient to evaluate the Mn availability to soybean. The "fritted" Mn source resulted lower agronomic effectiveness in comparison to SS+Mn and MnSO4...(Complete abstract, acess undermentioned eletronic adress) / Mestre

Made available in DSpace on 2014-06-11T19:23:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-11-30Bitstream added on 2014-06-13T20:50:15Z : No. of bitstreams: 1 saojoao_acg_me_jabo.pdf: 358627 bytes, checksum: befd4f38aba33e9eb069a53a5928dfac (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A greenhouse experiment was carried out to evaluate the effects in soil, plant and soybean dry matter yield in function of manganese rates and sources. The distribution of manganese in different fractions was evaluated. A completely randomized design in a factorial arrangement 3x6x3 (soil x rate x Mn source) was used. The soils were classified as Typic Quartzipsamment (soil 1), clayey Typic Haplustox (soil 2) and sandy clay loam Typic Haplustox (soil 3). Mn rates were 0, 5, 10, 20, 40 e 60 mg kg-1 using single superphosphate + Mn (micronutrient incorporated in ordinary superphosphate granulation), Fritted Mn and manganese sulphate. The available Mn was determined with Mehlich-1 (M-1) and DTPA. The extractants used to evaluate Mn solubility in fertilizers were: water, 20 g L-1 citric acid and neutral ammonium citrate solutions. The agronomic effectiveness of the manganese sources was calculated using manganese sulphate as reference. Using sequential extraction, the soil Mn was partitioned into exchangeable, organic, amorphous Fe and Al oxides, crystalline Fe and Al oxides and residual forms. Mn fertilization increased Mn content in soybean shoot, regardless to soil and source considered. Dry matter yield depended of Mn initial in soils. In soils 1 and 2, which had low Mn content, occured an increase in soybean dry matter yield. The DTPA and M-1 extractants were efficient to evaluate the Mn availability to soybean. The fritted Mn source resulted lower agronomic effectiveness in comparison to SS+Mn and MnSO4...(Complete abstract, acess undermentioned eletronic adress)

Elevated levels of arsenic (As) in soils and water around the world are both a significant human health and environmental hazard. With increasing global water demands, there is a requirement to further the understanding of the biogeochemical cycling of As from soils and sediments. This thesis focussed on exploring the environmental controls on the occurrence and subsequent mobility of As in a range of natural environments. Arsenic was found to undergo mobilisation from both river sediments and upland peats under changing environmental conditions. The transport of As was found to be correlated with both iron (Fe) and organic carbon (OC), however temporal changes in both sediment/soil composition and movement of water through catchments have a important role in controlling the ultimate transport of As within the environment. A range of investigative methods were employed to study the occurrence and mobility of As within the river sediments of the Allier and Loire Rivers (France), including sequential extraction procedures and batch incubation studies. Arsenic was associated with the reducible phases of sediments, indicating the major role of Fe(oxy)hydroxides in the storage of As in river sediments. In addition to the presence of labile As, the rapid release of As was dependent on the initial sediment composition. Temporal changes in sediment composition may therefore play an important role in controlling the movement of As within fluvial systems. The combination of lead (Pb) and strontium (Sr) isotopic analysis with sequential extraction studies of sediments from the Loire and Allier Rivers was able to determine the relative dominance of granites and basalts within the sediments. This approach provided a first order study on which to better understand the mineral origins of the sediments. The analysis of multiple Pb isotopes was able to eliminate possible anthropogenic contribution to contamination within the sediments, confirming the importance of geogenic cycling of As within the rivers. Information on the origin of mineral formation was obtained through 87Sr/86Sr isotopic analysis, with the formation of Fe-minerals not occurring uniformly along the course of the rivers. While the Sr within the sediment phase targeting well-crystallised Fe(oxy)hydroxides was in equilibrium with the sampled river water, the formation of amorphous Fe minerals was likely occurring in waters upstream of the study sites, within the Massif Central. Total concentration profiles peat from two subcatchments within the Peak District (United Kingdom) provided evidence for both the retention and post depositional movement (PDM) of As within the solid phase, dependent on local conditions. For the first time, the partitioning of As was determined within ombrotrophic peat, and found to be in contrast to Pb, with oxidisible As (likely associated with organic matter) dominating, while Pb was found predominantly within the reducible sediment phase. High temporal resolution monitoring of the organic-rich streamwater draining the peat showed the transport of As was variable, with As found largely in the soluble form despite extensive peat erosion. The evidence for PDM, and the subsequent soluble transport of As demonstrated the importance of biogeochemical processes in releasing As from the solid phase. Once mobilised, both the ratio of Fe:OC and the form of Fe were found to be factors controlling transport of As, with the flushing of stored porewaters an important contribution to As transport from the peat. Despite OC-rich waters, the occurrence of high concentrations of Fe may dominate control of As within the aqueous phase. At relatively high (>0.2) Fe:OC ratios, the particle size distribution of As was closely correlated with that of >1um Fe, although the presence of dissolved and colloidal As was found even within these waters. Given the temporal variability of As transport within the streams, knowledge of the mixing order and ratio between Fe, OC, and As within natural waters may be required for prediction of the mobility and ultimate fate of As.

In shallow lake systems, phosphorus (P) availability to cyanobacteria populations is often controlled by the release (internal loading) or sequestration of sediment P. This study provides novel insight into the feedbacks between the water column and benthic P pools across multiple time scales and explain how these dynamics influence chemical partitioning of P in lake sediment. Phosphorus partitioning in seasonal sediment core time series collected from a shallow eutrophic bay of Lake Champlain were quantified with SEDEX and enzyme hydrolysis selective extraction schemes. Time series extraction data were interpreted with concurrent water column physical and biogeochemical monitoring data to examine the relationship between water column dynamics and P partitioning of near-surface sediments in this intensively monitored system. Nonmetric multidimensional scaling analysis (NMDS) indicates that both sediment and water column time series cluster seasonally, linking water column variables such as pH, thermal stratification, and dissolved oxygen concentrations to the behavior of sediment P pools over the course of a year. Iron (FeP), exchangeable (Ex-P), calcium carbonate bound P (Ca-P) pools, and enzyme labile P were highly dynamic, especially in spring and summer. The SEDEX concentration data indicated that the sediment was mainly composed of inorganic bound P (De-P), but FeP and Ex-P pools proportionally varied most between sampling dates. Remarkably, while highly dynamic on an intra-annual timescale, the sediment ultimately returned to similar P concentration and chemical partitioning by late fall. The hysteretic nature of this interaction between water column dynamics and sediment P inventory/partitioning was clearly driven by systematic seasonal changes in water column physical, chemical, and ecological conditions governed by northern Vermont’s climate and the physical configuration of the bay and its watershed. This study provides novel insight into the unique challenges associated with improving water quality in lake systems impacted by internal loading of legacy P.