Determination of Carbon,Hydrogen, Nitrogen and Sulfur in Geological Materials Using Elemental Analysers     

Maria F. Gazulla  Marta Rodrigo  Monica Orduña  Carmen M. Gómez 《Geostandards and Geoanalytical Research》2012,36(2):201-217

This article describes a series of methods developed for the determination of total carbon (C_Total), organic carbon (C_org), hydrogen, nitrogen and sulfur. The following elemental analysers were used: LECO model RC‐412 for the determination of organic carbon, total carbon and hydrogen; LECO model CS‐200 for the determination of total carbon and sulfur; LECO model TN‐400 for the determination of nitrogen; and LECO model TruSpec CHNS for the determination of organic carbon, total carbon, hydrogen, nitrogen and sulfur. Uncertainty and limits of detection and quantification were calculated for each method, as well as the running costs to define the most effective instrument for each material and each analyte. Accuracy was checked by the application of the Sutarno–Steger test. Finally, a compilation of the results obtained in the determination of C_Total, C_org, H, N and S in forty‐nine reference materials is presented.  相似文献   

Partition of arsenic in soils sediments and the origin of naturally elevated concentrations in groundwater of the southern pampa region (Argentina)     

María del Carmen Blanco  Juan Darío Paoloni  Hector Morrás  Carmen Fiorentino  Mario Eduardo Sequeira  Nilda N. Amiotti  Oscar Bravo  Silvana Diaz  Martín Espósito 《Environmental Earth Sciences》2012,66(7):2075-2084

Excessive arsenic concentrations above the Argentinean and WHO guidelines for drinking water (10 μg L⁻¹) affects shallow aquifers of the southern Pampean Plain (Argentina) hosted in the Pampean and the Post Pampean formations (loess and reworked loess; Plio-Pleistocene–Holocene). Health problems related to high As concentrations in drinking waters are known as Endemic Regional Chronic Hydroarsenicism. Hydrochemistry of shallow groundwaters and soil geochemistry were investigated aiming to (1) understand the partition of As in the solid phase and its relationship with unacceptable As concentrations in waters, (2) identify the provision source of As to groundwaters. Only 5% of the samples had As concentrations <10 μg L⁻¹; in 27% As concentrations ranged from 10 to 50 μg L⁻¹ and in 58% it reached 60–500 μg L⁻¹. The coarse fraction (50–2,000 μm) hosts about 27% of the total As in the solid phase, being positively correlated to Ba (p < 0.01; r ² = 0.93). About 70% is included in the <2 μm fraction and had positive correlations of As–Fe (p < 0.05; r ² = 0.85) and As–Cr (p < 0.05; r ² = 0.68). Soils and sediment sand fractions of vadose zones are the primary sources of As in shallow groundwater while adsorption–desorption processes, codisolution–coprecipitation, and evaporation during the dry seasons raise As concentrations in waters exceeding the guideline value for drinking water.  相似文献   

Development of unconfined historic lava flow fields in Tenerife: implications for the mitigation of risk from a future eruption     

M. Carmen Solana 《Bulletin of Volcanology》2012,74(10):2397-2413

Historic and recent (last 2,000?years) eruptions on the active volcanic island of Tenerife have been predominantly effusive, indicating that this is the most probable type of activity to be expected in the near future. In the past, lava flow invasion caused major damage on the island, and as the population and infrastructure have increased dramatically since the last eruption, lava flows are the most important short-term volcanic risk on Tenerife. Hence, an understanding of lava flow behaviour is vital to manage risks from lava flows and minimise future losses on the island. This paper focuses on the lava flows from the historic eruptions in Tenerife, providing new data on the volumes emitted, advance rates and the timing of the emplacement of flows. The studies show three main stages in the development of unconfined flow fields: the first stage, corresponding to the fast advance of the initial fronts during the first 24?C36?h of eruption (reaching calculated velocities of up to 1.1?m/s); the second stage, in which fronts stagnate; and a third stage, in which secondary lava flows develop from breakouts 4?C7?days after the initial eruption and farther extend the flow field (velocities of up to 0.02?m/s have been calculated for this stage). The breakouts identified originated at sites both proximal and distal to the vent and, in both cases, caused damage through lengthening and widening the original flow field. Hence, the probability of damage from lavas to land and property is highest during stages 1 and 3, and this should be accounted for when planning the response to a future effusive eruption. Tenerife??s lava flows display a similar behaviour to that of lava flows on volcanoes characterised by basaltic effusive activity (such as Etna or Kilauea), indicating the possibility of applying forecasting models developed at those frequently active volcanoes to Tenerife.  相似文献   

Changes in Mediterranean high mountain Trichoptera communities after a 20-year period     

Marta Sáinz-Bariáin  Carmen Zamora-Muñoz  Juan J. Soler  Núria Bonada  Carmen Elisa Sáinz-Cantero  Javier Alba-Tercedor 《Aquatic Sciences - Research Across Boundaries》2016,78(4):669-682

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Metal(loid)s Uptake and Effects on the Growth of Helianthus tuberosus Cultivar‐Clones Under Multi‐Polluted Hydroponic Cultures          下载免费PDF全文

Blanca Montalbán  Mª Carmen Lobo  Juan Alonso  Araceli Pérez‐Sanz 《洁净——土壤、空气、水》2016,44(10):1368-1374

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An Updated Probabilistic Seismic Hazard Assessment for Romania and Comparison with the Approach and Outcomes of the SHARE Project     

Florin Pavel  Radu Vacareanu  John Douglas  Mircea Radulian  Carmen Cioflan  Alex Barbat 《Pure and Applied Geophysics》2016,173(6):1881-1905

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Messinian deposits and erosion in northern Tunisia: inferences on Strait of Sicily during the Messinian Salinity Crisis     

Narjess El Euch-El Koundi  Serge Ferry  Jean-Pierre Suc  Georges Clauzon  Mihaela Carmen Melinte-Dobrinescu  Christian Gorini  Anissa Safra  Fouad Zargouni 《地学学报》2009,21(1):41-48

Outcrops, offshore wells, electric logs and seismic profiles from northern Tunisia provide an opportunity to decipher the Messinian Salinity Crisis in the Strait of Sicily. Messinian deposits (including gypsum beds) near the Tellian Range reveal two successive subaerial erosional surfaces overlain by breccias and marine Zanclean clays, respectively. In the Gulf of Tunis, Messinian thick evaporites (mostly halite) are strongly eroded by a fluvial canyon infilled with Zanclean clays. The first erosional phase is referred to the intra-Messinian tectonic phase and is analogous to that found in Sicily. The second phase corresponds to the Messinian Erosional Surface that postdates the marginal evaporites, to which the entire Sicilian evaporitic series must refer. The Western and Eastern Mediterranean basins were separated during deposition of the central evaporites.  相似文献   

X-ray Computed Tomography study of the influence of consolidants on the hydric properties of sandstones for stone conservation studies     

Vicente G. Ruiz de Argandoa  Lope Calleja  ngel Rodríguez-Rey  Luis Miguel Surez del Río  Carmen Celorio 《Engineering Geology》2009,103(3-4):69-75

X-ray Computed Tomography (X-ray CT) has been used to study the petrophysical characteristics of a Jurassic sandstone from Asturias (Northern Spain) used as building stone in several monuments in the region. CT monitoring of water capillarity tests has made it possible to visualize the movement of water inside the samples, to relate this movement with texture characteristics, and to measure the height reached in successive images, thereby determining the capillary penetration coefficient; based on this coefficient, the effective capillary pore radius has also been estimated. An advantage of the use of CT is that, as the information comes from the sample interior, border effects that can be generated in the external faces can be avoided.The CT was also used to visualize how a commercial organosilicon consolidant penetrates inside the rock by means of capillarity, a usual way of consolidant application in stone restoration processes. The coefficient of capillary penetration of the product, determined on the basis of the measurements made on the tomographic images, is 53% less than that of water. The influence of rock texture characteristics on the capillarity both of the consolidant and the water was also observed.The samples underwent CT water capillarity studies before and after the consolidant application, proving that the treatment improves the rock's hydric properties. The coefficient of capillary penetration decreased by 24% following the application of the consolidant, whereas the effective pore radius decreased by more than 40%.  相似文献   

Valorization of olive stone as adsorbent of chromium(VI): comparison between laboratory- and pilot-scale fixed-bed columns     

M. Ángeles Martín-Lara  Mª Carmen Trujillo Miranda  A. Ronda Gálvez  A. Pérez Muñoz  M. Calero de Hoces 《International Journal of Environmental Science and Technology》2017,14(12):2661-2674

The main aim of this work is to study the effect of scaling in the biosorption of chromium(VI) onto olive stone in two different fixed-bed columns. Firstly, the effect of flow rate, bed depth and inlet concentration of Cr(VI) in both columns was analyzed. The results revealed a better operation for lower flow rates, higher bed heights and lower inlet concentrations of metal. When decreasing flow rate, the operation time of the column increases. Therefore, as the solution flow rate increased the breakthrough and the exhaustion times decreased. An increase in bed depth increases the quantity of chromium eliminated and thus, the higher sorption capacity of the system. A decrease in the inlet concentration of chromium produces a delay in exhaustion time, and larger volumes of solution could be treated. The results were fitted to the BDST model, obtaining that the adsorptive capacity of the bed depth is similar in laboratory- and pilot-scale fixed-bed columns, considering the biosorption capacity as a biosorption-coupled reduction process. Results also could indicate that scaling affects more to the reduction process than properly biosorption process. The experimental data were also fitted to Adams–Bohart, Thomas, Yoon–Nelson and dose–response models. A good fit of the biosorption process of Cr(VI) was found for dose–response and Adams–Bohart models.  相似文献   

Surface evolution of salt‐encrusted playas under extreme and continued dryness          下载免费PDF全文

Octavio Artieda  Alfonso Davila  Jacek Wierzchos  Peter Buhler  Rafael Rodríguez‐Ochoa  Juan Pueyo  Carmen Ascaso 《地球表面变化过程与地形》2015,40(14):1939-1950

Miocene continental saltpans are scattered in the Central Valley of the Atacama Desert, one of the driest regions on Earth. These evaporitic deposits are hydrologically inactive, and are detached from groundwater brines or aquifers. The surface of the saltpans, also known as salars, comprises desiccation polygons, commonly with nodular salt structures along their sides. The morphology and bulk mineralogy of salt polygons differs between and within salars, and the shape and internal structure of salt nodules varies between different polygon types. Based on field observation, and mineralogy and crystallography data, we generated a conceptual model for the genesis and evolution of these surface features, whereby rare rainfall events are responsible for the transformation of desiccation salt polygons and the initial formation of salt nodules along polygon borders. In addition, frequent, but less intense, deliquescence events further drive the evolution of salt nodules, resulting in a characteristic internal structure that includes laminations, and changes in porosity and crystal morphologies. As a result, and despite the extreme dryness, the surfaces of fossil salars are dynamic on timescales of several years to decades, in response to daily cycles in atmospheric moisture, and also to rare and meager rainfall events. We propose that fossil salars in the Atacama Desert represent an end stage in the evolution of evaporitic deposits under extreme and prolonged dryness. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献