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41.
The aim of the present study is the petrographic and chemical characterization of the coal at the Figueira Power Plant, Paraná, Brazil, prior and after the beneficiation process and the chemical characterization of fly and bottom ashes generated in the combustion process.Petrographic characterization was carried out through maceral analysis and vitrinite reflectance measurements. Chemical characterization included proximate analysis, determination of calorific value and sulphur content, ultimate analysis, X-ray diffraction, X-ray fluorescence, Inductively Coupled Plasma — Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma — Atomic Emission Spectrometry (ICP-AES) analysis, and determination of Total Organic Carbon (TOC) content.Vitrinite reflectance analyses indicate a high volatile B/C bituminous coal (0.61 to 0.73% Rrandom). Maceral analyses show predominance of the vitrinite maceral group (51.6 to 70.9 vol.%, m.m.f). Except of the Run of mine (ROM) coal sample, the average calorific value of the coals is 5205 kcal/kg and ash yields range from 21.4 to 38.1 wt.%. The mineralogical composition (X-ray diffraction) of coals includes kaolinite, quartz, plagioclase and pyrite, whereas fly and bottom ashes are composed by mullite, ettringite, quartz, magnetite, and hematite. Analyses of major elements from coal, fly and bottom ashes indicate a high SiO2, Al2O3, and Fe2O3 content. Trace elements analysis of in-situ and ROM coals by ICP-MS and ICP-AES show highest concentration in Zn and As. Most of the toxic elements such as As, Cd, Cr, Mo, Ni, Pb, and Zn are significantly reduced by coal beneficiation. Considering the spatial distribution of trace elements in the beneficiated coal samples, which were collected over a period of three months, there appears to be little variation in Cd and Zn concentrations, whereas trace elements such as As, Mo, and Pb show a larger variation.In the fly and bottom ashes, the highest concentrations of trace elements were determined for Zn and As. When compared with trace element concentrations in the feed coal, fly ashes show a significant enrichment in most trace elements (As, B, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Sb, Tl, and Zn), suggesting a predominantly volatile nature for these elements. In contrast, Sn is distributed evenly within the different ash types, whereas U shows depleted concentration in both bottom and fly ash samples.According to the International Classification of in-seam coals the Cambuí coals are of para/ortho bituminous rank of low grade (except for the ROM sample), and are characterized by the predominance of vitrinite macerals. 相似文献
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Javier Aguilar-Carrillo Laura Barrios Fernando Garrido María Teresa García-González 《Applied Geochemistry》2007
To asses the efficiency of two by-products (phosphogypsum (PG) and sugar foam (SF), rich in gypsum and calcium carbonate, respectively) in the immobilization of three toxic elements (As, Cd and Tl) in an acidic soil, batch-scale sorption and desorption experiments were conducted after 18 months of in situ amendment application. The Langmuir isotherms applied for sorption studies showed that the estimated maximum sorption capacity of the elements was highest in the SF-treated samples. The amount of element retained and the percentage of extraction after TCLP tests indicated that those samples amended with sugar foam (SF and PG + SF) had the potential to immobilize As, Cd and Tl in an acidic soil with low sorptive capacity. In addition to sorption and desorption experiments, scanning electron microscopy in back-scattered electron mode (SEM-BSE) showed the formation of Al-hydroxy polymers which provides the soil with additional sorption capacity. The three target elements were associated with the Al-hydroxy polymers, probably through direct coordination or the formation of ternary complexes. By means of statistical analysis it has been found that sorption processes of As, Cd and Tl in this soil mainly depend on the treatment, whereas desorption is an element-dependent process. 相似文献
43.
Josh E. Moncrieff Laurence R. Bentley Heyddy Calderón Palma 《Hydrogeology Journal》2008,16(1):183-197
Nicaragua’s León-Chinandega aquifer has seen extensive contamination by persistent organochlorine pesticides applied over
decades of intensive agricultural activity. Models of flow and transport of a 330 km2 sub-region of the aquifer were developed to test conceptual models of contaminant transport, to constrain the value of certain
key transport parameters, and to investigate contamination-related concerns raised in past studies. To support these models,
a variety of hydrogeologic and geochemical data were collected. It was concluded that the organochlorine pesticides seen in
groundwater originate in soils, and are transported to the water table through widespread preferential flow, through shortcutting
around wells, or through wind-blown particles delivered to poorly protected hand-dug wells. The distribution coefficient (K
d) of these pesticides is estimated to be between 0.1 and 100 ml/g and the concentration of pesticides being delivered to the
water table is estimated to be between 102 and 105 ng/L. It was found that the distribution and concentration of pesticides in the aquifer would be affected by an increase
in groundwater abstraction within the region.
Résumé L’aquifère du León-Chinandega au Nicaragua a été soumis à des contaminations étendues par des pesticides organochlorés persistants qui ont été répandus pendant des dizaines d’années d’agriculture intensive. Des modèles d’écoulement et de transport d’une sous-région de 330 km2 de l’aquifère ont été construits pour tester des modèles conceptuels du transport de contaminants, pour contraindre la valeur de certains paramètres de transport clefs, et pour étudier les problèmes liés au transport de contaminations qui avaient été rencontrés lors d’études précédentes. Différents types de données hydrogéologiques et géochimiques ont été collectés pour réaliser ces modèles. La conclusion montre que les pesticides organochlorés rencontrés dans les eaux souterraines proviennent des sols et qu’ils sont transportés jusqu’à l’aquifère via de grandes zones d’écoulement préférentiel, via des raccourcis hydrauliques autour des puits, ou encore via des particules emportées par le vent et tombées dans des puits creusés à la main et mal protégés. Le coefficient de distribution (K d) de ces pesticides est estimé entre 0.1 et 100 ml/g et la concentration de pesticides arrivant dans la nappe est estimée entre 102 et 105 ng/L. L’étude a montré qu’une augmentation des prélèvements d’eau souterraine dans la région aurait un impact sur la distribution et la concentration des pesticides dans l’aquifère.
Resumen El acuifero León-Chinandega (Nicaragua) presenta una contaminación extensiva por la aplicación de plaguicidas organoclorados en la agricultura intensiva durante décadas. Se han desarrollado modelos de flujo y transporte de una subregión del acuífero de 330 km2 para comprobar los modelos conceptuales del transporte de contaminantes, estimar los valores de ciertos parámetros clave de transporte e investigar los temas relacionados con la contaminación en estudios anteriores. Para elaborar estos modelos, se recogió una variedad de datos hidrogeológicos y geoquímicos. Se ha concluido que los plaguicidas organoclorados presentes en el agua subterránea se originan en el suelo y son transportados hacia el nivel freático a través de flujos preferentes generalizados, a través de cortes alrededor de los pozos o a través de partículas transportadas por el viento depositadas en pozos excavados a mano con poca protección. El coeficiente de distribución (K d) de estos plaguicidas se ha estimado entre 0.1 y 100 ml/g y la concentración de plaguicidas que sale hacia el nivel freático se estima que puede estar entre 102 y 105 ng/L. Se ha concluido que el incremento de la extracción de aguas subterráneas dentro de la región afectaría la distribución y concentración de plaguicidas en el acuífero.相似文献
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A. J. Westphal J. C. Bridges D. E. Brownlee A. L. Butterworth B. T. De Gregorio G. Dominguez G. J. Flynn Z. Gainsforth H. A. Ishii D. Joswiak L. R. Nittler R. C. Ogliore R. Palma R. O. Pepin T. Stephan M. E. Zolensky 《Meteoritics & planetary science》2017,52(9):1859-1898
Recent observations indicate that >99% of the small bodies in the solar system reside in its outer reaches—in the Kuiper Belt and Oort Cloud. Kuiper Belt bodies are probably the best‐preserved representatives of the icy planetesimals that dominated the bulk of the solid mass in the early solar system. They likely contain preserved materials inherited from the protosolar cloud, held in cryogenic storage since the formation of the solar system. Despite their importance, they are relatively underrepresented in our extraterrestrial sample collections by many orders of magnitude (~1013 by mass) as compared with the asteroids, represented by meteorites, which are composed of materials that have generally been strongly altered by thermal and aqueous processes. We have only begun to scratch the surface in understanding Kuiper Belt objects, but it is already clear that the very limited samples of them that we have in our laboratories hold the promise of dramatically expanding our understanding of the formation of the solar system. Stardust returned the first samples from a known small solar system body, the Jupiter‐family comet 81P/Wild 2, and, in a separate collector, the first solid samples from the local interstellar medium. The first decade of Stardust research resulted in more than 142 peer‐reviewed publications, including 15 papers in Science. Analyses of these amazing samples continue to yield unexpected discoveries and to raise new questions about the history of the early solar system. We identify nine high‐priority scientific objectives for future Stardust analyses that address important unsolved problems in planetary science. 相似文献
47.
Juan Bautista Spacapan Alejandro D´Odorico Octavio Palma Olivier Galland Kim Senger Remigio Ruiz Rene Manceda Hector Armando Leanza 《Basin Research》2020,32(1):3-24
Igneous sills and laccoliths emplaced in sedimentary basins may significantly impact petroleum systems, both positively and negatively. Igneous intrusions provide heat to maturate regionally immature organic-rich host rocks, act as fractured reservoirs hosting commercial accumulations of hydrocarbons, and form structures affecting fluid flow and trapping at different scales. Nevertheless, the petrophysical implications of igneous intrusions on their host rock are poorly known. In this study, we analyse 200 wells in the Río Grande Valley oil field, Neuquén basin, Argentina, where the main reservoirs are in fractured igneous sills. This dataset represents a globally unique possibility to characterize the igneous–host rock interaction using both wireline logs and core material. We identify a systematic Contact Low Resistivity Zone (CLRsZ) at both the upper and lower contacts of the sills emplaced in the organic-rich Vaca Muerta and Agrio Formations. We characterize the nature of these CLRsZ and their petrophysical properties by integrating resistivity and gamma ray well logs, petrographic analyses, petrophysical tests and geochemical analyses. The low resistivity signal of the CLRsZ is dominantly carried by massive-sulphide deposits, mainly pyrite, observed both in the host rock and the chilled margin of the sills. Well log images and porosity-permeability analysis on core plugs show that both the sills and their associated CLRsZ can act as carrier for fluid flow and reservoir for hydrocarbons storage. The thickness of the upper and lower CLRsZ correlates linearly with the thickness of the sill, and the volume of both the upper and lower CLRsZ represents ca. 40% with respect to the volume of their associated sill. The thickness of the CLRsZ represents ca. 13% of the thickness of contact aureole induced by the sills. In the CLRsZ, a great proportion of kerogen was transformed to hydrocarbon, so that CLRsZ were restricted to the innermost contact aureole of the sills. Our results show that the CLRsZ can have major implications on fluid flow and should be considered in reservoir models in volcanic basins hosting sills emplaced in organic-rich formations. 相似文献
48.
Sergio Palma Nelson Silva María Cristina Retamal Leonardo Castro 《Continental Shelf Research》2011,31(3-4):260-271
The horizontal and vertical distribution of jellyfish was assessed in the Chiloé Inland sea, in the northern area of the Chilean Patagonia. A total of 41 species of cnidarians (8 siphonophores, 31 hydromedusae, 2 scyphomedusae) were collected. Eleven jellyfish species were recorded for the first time in the area. Species richness was higher in spring than in winter (37 vs. 25 species, respectively). Species such as Muggiaea atlantica, Solmundella bitentaculata, and Clytia simplex were extremely abundant in spring. The total abundance (408,157 ind 1000 m?3) was 18 times higher in spring than in winter (22,406 ind 1000 m?3).The horizontal distribution of the most abundant species (four in winter, five in spring) showed decreasing abundances in the north–south direction in winter and spring. Peak abundances occurred in the northern microbasins (Reloncaví Fjord, Reloncaví and Ancud gulfs), where the water column stability, phytoplankton and zooplankton abundance were higher, compared with the southern microbasins (Corcovado Gulf, Boca del Guafo). During the spring higher jellyfish abundance season, the vertical distribution of the dominant species (except M. atlantica) showed peak values at mid-depth (30–50 m) and in the deepest sampled layer (50–200 m). This vertical distribution pattern reduced seaward transport in the shallowest layer through estuarine circulation and also limited mortality by predation in the more illuminated shallow layers. Thus, jellyfish were able to remain in the interior waters during the season of maximum biological production. 相似文献
49.
Janaina L. Oliveira Alessandra Eugênio Júlio C. Rodrigues de Azevedo Jorge Nozaki 《洁净——土壤、空气、水》2006,34(4):383-388
The sediment of Lagoa dos Patos‐MS, Brazil, was investigated to verify the influence of metal sulfides and oxyhydroxides of Mn and Fe on the heavy metal availability. The spectrophotometric method of methylene blue was used, with 8 interlinked tubes containing the samples with SnCl2, where N2 was introduced to release the H2S extracted with 6.0 mol L–1 HCl, and trapped in 0.05 M NaOH solution. The influence of SO42–, Mn(IV) and Fe(III) oxyhydroxides was investigated with samples constituted by a mixture of MnO2; Na2SO4; FeCl3, and sediments. The presence of SnCl2 was very important to avoid the interferences of iron and manganese oxyhydroxides. The method of standard addition was applied and the efficiency was (100.8 ± 9.4)%. The ratio among the quantities of metals potentially available and the acid volatile sulfide (AVS) indicate that the system presents small metals availability to the benthic community, by the existence of sulfide capable to immobilize the metal as insoluble sulfide. 相似文献
50.
In this study, we analyze the recent (1990–1997) seismicity that affected the northern sector (Sannio–Benevento area) of the Southern Apennines chain. We applied the Best Estimate Method (BEM), which collapses hypocentral clouds, to the events of low energy (Md max=4.1) seismic sequences in order to constrain the location and geometry of the seismogenetic structures. The results indicate that earthquakes aligned along three main structures: two sub-parallel structures striking NW–SE (1990–1992, Benevento sequence) and one structure striking NE–SW (1997, Sannio sequence). The southernmost NW–SE structure, which dips towards NE, overlies the fault that is likely to be responsible for a larger historical earthquake (Io max=XI MCS, 1688 earthquake). The northernmost NW–SE striking structure dips towards SW. The NE–SW striking structure is sub-vertical and it is located at the northern tip of the fault segment supposed to be responsible for the 1688 earthquake. The spatio-temporal evolution of the 1990–1997 seismicity indicates a progressive migration from SE (Benevento) to NW (Sannio) associated to a deepening of hypocenters (i.e., from about 5 to 12 km). Hypocenters cluster at the interface between the major structural discontinuities (e.g., pre-existing thrust surfaces) or within higher rigidity layers (e.g., the Apulia carbonates). Available focal mechanisms from earthquakes occurred on the recognized NW–SE and NE–SW faults are consistent with dip-slip normal solutions. This evidences the occurrence of coexisting NW–SE and NE–SW extensions in Southern Apennines. 相似文献