A long term (1989-2008) decreasing trend in black carbon and organic carbon surface concentrations is indicated by insitu measurements (IMPROVE) in the United States in winter months. The observed percent negative trend is higher in the western United States than the eastern region. This study examines how the observed trend relates to emission inventories of black carbon and organic carbon. Attention is paid to the contribution of emissions from the residential sector to the observed decreasing trend particularly over the western United States. A chemical transport model is used to relate the emission inventories to concentrations. A variety of bottom-up emission inventories are tested. Multiple linear regression was used to estimate the anthropogenic sources contributing to trends in BC and OC concentrations in winter months over US. The larger relative trend of carbonaceous aerosols in the west appears to be driven by the larger relative contribution of residential and transport sources to this region.

Carbonaceous fossil preservation is an important taphonomic window that provides critical perspectives on the evolutionary history of life. However, phylogenetic interpretation of carbonaceous fossils is not straightforward. This is largely because critical biological information is usually lost during fossilization and three-dimensional morphologies are flattened into two-dimensional compressions. Hence, innovative techniques and methods are required in order to better understand the evolutionary significance of these fossils. To achieve this goal, this dissertation is focused on using an array of innovative research techniques to investigate the paleobiology, biostratigraphy, and taphonomy of carbonaceous fossils in critical times of early life evolution, including Neoproterozoic and Cambrian. Chapters 2 to 5 in this dissertation present original research that helps to decipher hidden biological structures of various carbonaceous fossils using a series of research methods. An improved understanding of these carbonaceous remains will ultimately advance our knowledge regarding the early evolutionary history of life on Earth. Chapter two describes new cellular structures of the carbonaceous compression macrofossil Chuaria using backscattered electron scanning electron microscopy. The data show that Chuaria, which is one of the most common fossils in Neoproterozoic and whose phylogenetic interpretation has been uncertain, is likely a multicellular eukaryote. Chapter three is aimed to resolve a long debate on the depositional age of the Gouhou Formation in the Huaibei region of North China and to constrain the Precambrian-Cambrian (P-C) boundary in this area. Using a low manipulation maceration technique, this study reveals a diverse assemblage of organic-walled microfossils from the lower Gouhou Formation, suggesting that the lower Gouhou Formation is Tonian in age and the P-C boundary may be located within the Gouhou Formation. Chapter four reports a group of problematic carbonaceous compression macrofossils from the Hetang Formation in South China. Taphonomic analysis using optical and electron microscopy tentatively suggests that these carbonaceous macrofossils are probably carapaces of bivalved arthropods. The last chapter describes a group of sponge fossils with carbonaceous preservation from the early Cambrian Hetang Formation in South China. Using an array of electron microscopy techniques, this study reveals that siliceous spicules of the Hetang sponges have large axial filaments and large proportions of organic material, suggesting early sponge in the Precambrian and Cambrian may have had weakly mineralized or entirely organic skeletons. Results from this study helps to reconcile the apparently conflicting molecular clocks, biomarker fossils, and spicular fossils of early sponges. / PHD / Carbonaceous fossils can provide important information about the life on Earth in deep time. However, biological interpretation of carbonaceous fossils is not always straightforward, largely because critical biological information is usually lost during fossilization. To address this matter, this dissertation presents original research that helps to decipher hidden biological structures of various carbonaceous fossils using a series of innovative research techniques and methods. Specifically, Chapter two describes new cellular structures of the carbonaceous compression macrofossil Chuaria using backscattered electron scanning electron microscopy. The data show that Chuaria, which is one of the most common fossils in Neoproterozoic and whose biological interpretation has been uncertain, is likely a multicellular eukaryote. Chapter three is aimed to resolve a long debate on the depositional age of the Gouhou Formation in the Huaibei region of North China and to constrain the Precambrian-Cambrian (P-C) boundary in this area. Using a low manipulation maceration technique, this study reveals diverse organic-walled microfossils from the lower Gouhou Formation, suggesting that the lower Gouhou Formation is Tonian in age and the P-C boundary may be located within the Gouhou Formation. Chapter four reports a group of problematic carbonaceous compression macrofossils from the Hetang Formation in South China. This study, using optical and electron microscopy, suggests that these carbonaceous macrofossils are probably carapaces of bivalved arthropods. The last chapter describes a group of sponge fossils with carbonaceous preservation from the early Cambrian Hetang Formation in South China. Using an array of electron microscopy techniques, this study reveals that the Hetang sponges developed spicules with large proportions of organic material, suggesting early sponge in the Precambrian and Cambrian may have had weakly mineralized or entirely organic skeletons. Therefore, an improved understanding of these carbonaceous remains presented in this dissertation will ultimately advance our knowledge regarding how the early life on Earth evolved through time.

Carbonaceous chondrites have an approximately solar bulk composition, with some exceptions (e.g. H), and exhibit a range of parent body alteration. Investigations of both pristine and altered chondrites yield valuable insight into the processes and conditions of the early Solar System prior to and resulting in the planets we observe today. Such insight and the dynamic models developed by astrophysicists are constrained by chemical, mineralogical, and textural characteristics of chondrite components (chondrules, refractory inclusions, metal, and matrix). This dissertation uses a variety of chondritic components to address the following: 1) what do correlations within a population of refractory inclusions reveal about early Solar System conditions; 2) what is the distribution of trace elements among chondrite components and how does this affect component formation from precursor aggregation to chondrite accretion; and 3) can metal associated with chondrules further our understanding of chondrule formation and/or deformation? The first two objectives were investigated using suite of carbonaceous Ornans-group (CO) chondrites of varying petrologic grades (Colony CO3.0, Kainsaz CO3.2, Felix CO3.3, Moss CO3.6, and Isna CO3.8). These chondrites were analyzed using several analytical techniques including: electron microprobe element mapping, a modal phase analysis algorithm, and laser ablation inductively coupled plasma mass spectrometry. Within the comprehensive dataset of refractory inclusion characteristics (area, major mineralogy, bulk major chemistry, texture, and rare Earth element (REE) patterns and abundances) there is an overwhelming lack of correlations implying that thermal processing prior to accretion was stochastic and that sorting was minimal. Only two CO chondrites were analyzed for REE abundances (Colony and Moss). While refractory inclusions exhibit the greatest enrichments in REE relative to CI, after modal recombination chondrule glass contributes most significantly to the bulk REE budget in both chondrites. The bulk mean REE patterns for both Colony and Moss are flat and approximately CI in abundance while the mean REE patterns for components are nearly flat with relative enrichments (~10x CI for both chondrule glass and refractory inclusions) or depletions (chondrule olivine) relative to CI. Lack of correlations between REE and other characteristics, nearly flat REE patterns and nearly equivalent enrichment factors relative to CI across chondrite groups, including the CO chondrites analyzed here, implies that REE were equilibrated in precursor material prior to chondrite component formation. We propose a scenario for the equilibration of REE with vapor-solid or solid-solid reactions with subsequent accretion of chondrite components. Metal-rich chondrules in Acfer 139, a carbonaceous Renazzo-group (CR) chondrite were used to address the final objective. Chemical information was obtained using electron microprobe quantitative analysis and element mapping, electron backscatter diffraction was used to analyze the crystal structure of the metal nodules, and computed tomography provided insight into the 3D relationships of the metal. Eight chondrules with abundant metal nodules, both as rims and within the chondrule interior, were analyzed in detail. Chondrule A is of particular interest as it contains three concentric metal layers. A majority of the metal nodules fall on the calculated condensation trajectory of Co/Ni in a vapor of solar composition with the interior metal nodules containing higher Ni wt% and Co wt% than the rim nodules. Twinning is evident in many of the metal nodules and could indicate a ubiquitous parent body deformation process. Chemical inhomogeneity of Ni only occurs within the metal nodules of chondrule A and implies these metal nodules were reheated to high temperatures. The combination of chemical inhomogeneity, multiple sets of twins, and other evidence of strain imply that the formation of these chondrules was not straightforward and involved multiple iterations of heating, and potentially addition of material. A plausible model of chondrule formation in the early Solar System must be able to account for this more complicated thermal and alteration history and produce the chemical and textural variety of chondrules present in the region of chondrite accretion.

Unconventional gas resources have become important as an environment- friendly source of fuel. It is important to understand the pore level geometries of grains and voids in mudrocks in order to understand the flow potential of gas from these rocks. Recent observations of nanopores within carbonaceous material in mudrocks have led to the hypothesis that such material provides conduits for gas migration within the mudrock matrix. This hypothesis requires that the carbonaceous material exist not as isolated grains but as connected clusters of grains within the mudrock. To examine this hypothesis, we develop an algorithm for the grain-scale modeling of the spatial distribution of grains of carbonaceous matter in a matrix of non-carbonaceous material (silt, clay). The algorithm produces a grain-scale model of the sediment which is precursor to a mudrock, then a sequence of models of the grain arrangement as burial compacts the sediment into mudrock. The carbonaceous material is approximated by the simplest possible geometric model of spherical grains. These grains are distributed randomly within a population of other spheres that represent silt and clay grains. A cooperative rearrangement algorithm is used to generate a disordered packing of the grain mixture having a prescribed initial porosity. This model represents the sediment precursor of the shale in its original depositional setting. Periodic boundary conditions are imposed on the packing to eliminate wall-induced artifacts in the grain arrangement; in effect the packing extends infinitely in all three coordinate directions. We simulate compaction of the model sediment by incrementally rescaling the vertical coordinate axis, repeating the cooperative rearrangement calculation with periodic boundaries after each increment. We determine the size distribution of clusters of touching carbonaceous grains, focusing particularly upon the approach toward percolation (when a cluster spans the entire packing). The model allows estimation of threshold fraction of carbonaceous material for significantly connected clusters to form. Beyond a threshold degree of compaction, connected clusters become much more prevalent. Other factors affecting the threshold fraction such as ductility of the carbonaceous material is also evaluated. Ductility is modeled by taking a grain consisting inner rigid core covered by the outer soft shell which can be penetrated and deformed during geometrical transformation. The emergence of large numbers of clusters, or of a few large clusters, increases the probability that nanoporous conduits within the clusters would intersect a fracture in the mudrock. This should correlate with greater producibility of gas from the mudrock. Thus the dependence of the statistics of the clusters upon other parameters, such as the fraction of carbonaceous material, porosity, degree of compaction, etc., could be useful for estimating resource quality. For example, it is observed that the threshold concentration of carbonaceous material in the initial sediments for “significant clustering” enough to approach percolation is about 20 percent of the volume fraction. The degree of compaction needed to get “significant clustering” is 50%. / text

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Carbonaceous Compressions are a widespread preservational style for fossils, yet their taphonomy remains poorly understood. Previous studies focusing on the taphonomy of carbonaceous compressions have primarily looked at exceptionally preserved faunas in plane view. The precious nature of these fossils leaves destructive techniques of analysis out of the question, but these techniques are necessary if the taphonomy of carbonaceous compressions is to be deciphered. This study analyzes Neoproterozoic carbonaceous compressions from the Yangtze Gorges area in order to address this issue. Chuaria fossils from the Jiulongwan, Sixi, and Sifangtan sections of the Doushantuo Formation and Vendotaenia fossils from the Wuhe and Miaohe sections of the Denying Formation are microchemically analyzed in both plane view and cross section in order to gain a greater understanding of the makeup of carbonaceous compressions. Results confirm and elaborate on previous studies. Likely clay coats are detected on some Chuaria specimens, while they are absent on less thermally mature specimens. Evidence for sulfate reduction in association with carbonaceous compressions is found. Sulfur enrichment, rather than clay coats, is found in association with Vendotaenia fossils. These observations lead to the hypothesis that while organic remains require a very precise set of taphonomic conditions in order to be preserved as carbonaceous compressions, there may be more than one set of conditions that allow for preservation. More studies of a greater taxonomic and taphonomic range of carbonaceous compressions are needed, however, if the mechanisms which control this preservational pathway are to be fully understood. / Master of Science

Volatiles are critical in understanding the history of the solar system. We conducted two case studies intended to further this understanding. First, we analyzed the presence of CO2 on Iapetus. Second, we evaluated aqueous alteration in CM chondrites.We studied the distribution, stability and production of CO2 on Saturn's moon Iapetus. We determined that CO2 is concentrated exclusively on Iapetus' dark material with an effective thickness of 31 nm. The total CO2 on Iapetus' surface is 2.3x108 kg. However, CO2 should not be present because it has a limited residence time on the surface of Iapetus. Our thermal calculations and modeling show that CO2 in the form of frost will not remain on Iapetus' surface beyond a few hundred years. Thus, it must be complexed with dark material. However, photodissociation will destroy the observed inventory in ~1/2 an Earth year.The lack of thermal and radiolytic stability requires an active source. We conducted experiments showing UV radiation generates CO2 under Iapetus-like conditions. We created a simulated regolith by mixing crushed water ice with isotopically labeled carbon. We then irradiated it with UV light at low temperature and pressure, producing 1.1x1015 parts m-2 s-1. Extrapolating to Iapetus, photolysis could generate 8.4x107 kg y-1, which makes photolytic production a good candidate for the source of the CO2 detected on Iapetus.We also studied the aqueous alteration of metal-bearing assemblages in CM chondrites. We examined Murchison, Cold Bokkeveld, Nogoya, and Murray using microscopy, electron microprobe analysis and scanning electron microscopy. Alteration on CM meteorites occurred within at least three microchemical environments: S-rich water, Si-rich water and water without substantial reactive components. Kamacite alters into tochilinite, cronstedtite, or magnetite. Sulfur associated alteration can form accessory minerals: P-rich sulfides, eskolaite and schreibersite.Additionally, we determined that there were two alteration events for some CM chondrites. The first formed a hydrated matrix prior to accretion, indicated by unaltered kamacite surrounded by a hydrated matrix. The second occurred after parent body formation. This event is indicated by large regions with consistent alteration features, surrounded by other regions of less altered material.

Commercial granular and fibrous activated carbons have been studied for the removal of heavy metals from aqueous solutions. A wood based activated carbon (AUG WHK) and an activated carbon cloth (KoTHmex TC-66 C) based on polyacrylonitrile fibre as a precursor, were oxidised for different periods of time using nitric acid, ozone and electrochemical methods to introduce various acidic groups at the surface, thereby, enhancing metal binding capacity. Modified samples were subsequently studied for the specific removal of cadmium and mercury ions in solution and compared with the performance of a commercially available weak acid fibrous exchange material (Ecofil-Deco Ltd. K-4). Carbonaceous adsorbents were physically characterised by scanning electron microscopy, surface area and porosimetry (using N2 adsorption at 77K). There was a decrease in BET surface area betweenu ntreateda nd oxidised samples. Acid and electrochemically oxidised samples were completely stable although there was clear evidence of physical damage to ozone-oxidised carbons. Samples were also chemically characterised by pH titration, direct titration, X-ray photoelectron spectroscopy and elemental analysis. A significant increase in oxygen content was obtained after oxidation, which increased the total ion exchange capacity by a factor of approximately 3.3 compared to commercial as-received carbonaceous adsorbents. As the degree of oxidation increased, the point of zero charge was shifted to lower pH values, i. e. from 4.5 to 3.6. (Continues...).

Orientador: Roberto Perez Xavier / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-07-25T00:05:32Z (GMT). No. of bitstreams: 1 Silva_GilbertodeLimaPereira_M.pdf: 4720997 bytes, checksum: 8740815167ddd2826e2cd76a34789793 (MD5) Previous issue date: 1998 / Resumo: Litotipos carbonosos comumente hospedam ou ocorrem associados a mineralizações auríferas filoneanas nos depósitos mesotermais da Fazenda Canto (FC) e Fazenda Maria Preta (FMP), na seqüência Paleoproterozóica do Greenstone Belt do Rio Itapicuru, NE Brasil. Nestes depósitos, a matéria carbonácea (MC) ocorre principalmente como: (i) bandas retas a anastomosadas (Tipo I); (ii) grãos individuais compostos por agregados de sub-grãos altamente anisotrópicos (Tipo II); ou (iii) grãos individuais com textura interna homogênea (Tipo III). Estudos de espectroscopia Raman indicaram que estes tipos de MC correspondem a alguma forma de material grafítico microcristalino desordenado e definem um trend de grafitização do depósito FMP para o depósito FC, que é interpretado como sendo o resultado de diferentes graus de maturação da MC, que foi alcançado durante o metamorfismo regional no fácies xisto-verde e o alojamento de corpos graníticos no Greenstone Belt do Rio Itapicuru. Estudos de inclusões fluidas revelaram que os veios de quartzo mineralizados são dominados por populações de inclusões ricas em CO2 (Tipo 1), contudo grupos de inclusões H2OCO2 (Tipo 2) primárias, de baixa salinidade (<5% eq. NaCl), compreendem o tipo de inclusões dominantes em apenas alguns veios. Ambos os tipos de fluidos mineralizantes podem ser interpretados como parte de um sistema hidrotermal magmático-metamórfico profundo. No depósito FC, o geotermômetro da clorita (variedade ripidolita - limite inferior) e a paragnese sulfetada (arsenopirita-pirita-pirrotita - limite superior) indicaram limites de temperatura para a deposição do ouro entre 390ºC e 491ºC, com pressões estimadas entre 2.4 a 4.6 kbars, respectivamente. A MC do depósito FMP é isotopicamente mais leve (g13C= -23.3 0/00 a -30.8 0/00) do que a MC do depósito FC (g13C= -18.5 0/00 a -21.0 0/00) Estes valores de g 13C, juntos com as evidências geológicas apontam uma origem biogênica orgânica para a MC. Os composição de g13C calculada do CO2 derivado da oxidação ou hidrólise da MC, aplicando o equilíbrio isotópico calcita-grafita, produziu valores de g13C no intervalo de -9.3 °/00 a -12.8 °/00 entre 390°C e 491°C. Estes valores de 813C calculados são menores do que aqueles obtidos Rara carbonatos do depósito FC (-4.8 °/00 a -8.9 °/00). Por outro lado, os valores da composição de g13C calculada de CO2 de paleo-fluidos responsáveis pela formação de carbonatos (calcita-ankerita), aplicando o equilíbrio calcita-CO2, produziu valores no intervalo de -2.3 °/00 a -6.6 °/00 para temperaturas entre 390°C e 491°C. Estes valores de g13C calculados são compatíveis com o intervalo obtido para inclusões fluidas do depósito FC (-2.8 °/00 a 4.9 °/00) e confirmam que os minerais de alteração de carbonato foram formados pela ação de fluidos oriundos de fonte magmática ou metamórfica profunda. O processo de maturação termal da MC contribuiu pouco para mudanças na composição química e isotópica do fluido mineralizante. Com relação à deposição do ouro, a MC provavelmente atuou como: (1) uma barreira química, reduzindo a 102 do fluido mineralizante ou promovendo a imiscibilidade do fluido pela adição de pequenas quantidades de CH4 e N2 à fase fluida; elou (2) uma barreira física, adsorvendo ouro sobre sua superfície como carvão ativado. Adicionalmente, a MC pode ser usada como um guia indireto na prospeção de mineralizações auríferas / Abstract: Carbonaceous units commonly host or occur closely related to the lode-gold mineralization in the mesothermal Fazenda Canto (FC) and Fazenda Maria Preta (FMP) deposits of the Paleoproterozoic Rio Itapicuru Greenstone Belt, northeast Brazil. In these deposits, the carbonaceous matter (CM) occurs mainly as: (i) straight to anastomosing seams (Type I); (ii) single grains composed of an agglomerate of highly anisotropic subgrains (Type 11); or (iii) single grains with an homogeneous internar texture (Type III). Raman spectral characteristics indicated that these types of CM correspond to some form of microcrystalline disordered graphitic material and define a graphitization trend from the FMP to the FC deposit, which is interpreted as being the result of different degrees of thermal maturation of the CM that was attained during the regional greenschist metarnorphisrn and granite intrusions of the Rio Itapicuru Greenstone Belt. Fluid inclusion studies revealed that the mineralized quartz veins are dominated by populations of CO2-rich inclusions (Type 1), whereas primary groups of low salinity (< 5 wt% eq. NaCl) H2O-CO2 (±CH4 ± N2) inclusions (type 2) comprise the dominant inclusion type in only a few veins. Both types of mineralizing fluids may be interpreted as part of a deep metamorphic - magmatic hydrothermal system. In the FC deposit, chlorite (ripidolite variety - lower limit) geothermometer and sulfide assemblage (arsenopyrite-pyrite-pyrrhotite - upper limit) indicated a temperature of gold deposition between 390 °C to 491°C with estimated pressures of 2.4 to 4.6 kbars, respectively. The CM of the FMP deposit is isotopically lighter (g13C= -23.3 0/00 to -30.8 0/00) than the CM of the FC (g13C= -18.5 0/00 to -21.0 0/00) These g13C values, together with the geologie evidence, point towards a primarily biogenic organic origin for the CM. The calculated g13C compositions of CO2 derived by the oxidation or hydrolysis of the CM, applying the equilibrium calcite - graphite fractionation, yield g13C values in the range -9.3 0/00 to -12.8 0/00 at 390°C 491ºC. These calculated g13C values are lower than those obtained from carbonates of the FC deposit (-4.8 0/00 to -8.9 0/00). On the other hand, the calculated g13C compositions of CO2 from paleo fluids responsable bicarbonate (calcite-ankerite) formation, applying the equilibrium calcite - CO2 fractionation, yield g13 C values in the range -2.3 0/00 to -6.6 0/00 at 390°C ¿ 491ºC. These calculated g13C values are compatible with the range obtained from fluid inclusions of the FC deposit (-2.8 0/00 to -4.9 0/00) and insure that carbonate alteration minerals were formed by action of fluids from a magmatic or deep metamorphic source. The thermal maturation process of the CM contributed little to changes in the chemistry and isotopic composition of the mineralizing fluid. Regarding gold deposition, the CM is likely to have acted as: (1) a chemical trap, reducing the fO2 of the mineralizing paleo-fluids or enhancing fluid immiscibility by adding small quantities of CH4 and N2 to the fluid phase; and/or (2) a physical barrier, adsorbing gold on its surface as activated carbon. Addictionally the CM may be used as a indirect guide in surveys for gold mineralization / Mestrado / Metalogenese / Mestre em Geociências