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https://www.readbyqxmd.com/read/29238543/nitrogen-loss-from-karst-area-in-china-in-recent-50%C3%A2-years-an%C3%A2-in-situ-simulated-rainfall-experiment-s-assessment
#1
Xianwei Song, Yang Gao, Sophie M Green, Jennifer A J Dungait, Tao Peng, Timothy A Quine, Bailian Xiong, Xuefa Wen, Nianpeng He
Karst topography covers more than 1/3 of the People's Republic of China in area. The porous, fissured, and soluble nature of the underlying karst bedrock (primarily dolomite and limestone) leads to the formation of underground drainage systems. Karst conduit networks dominate this system, and rainfall takes a crucial role on water cycle at China karst area. Nitrogen loss from the karst system is of particular concern, with regard to nutrient use efficiency as well as water quality, as much of the karst system, including steeply sloping terrain, is used for intensive agriculture...
December 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/29216576/characterizing-adsorption-of-associating-surfactants-on-carbonates-surfaces
#2
Guoqing Jian, Maura Puerto, Anna Wehowsky, Clarence Miller, George J Hirasaki, Sibani L Biswal
HYPOTHESIS: The adsorption of anionic surfactants onto positively charged carbonate minerals is typically high due to electrostatic interactions. By blending anionic surfactants with cationic or zwitterionic surfactants, which naturally form surfactant complexes, surfactant adsorption is expected to be influenced by a competition between surfactant complexes and surfactant-surface interactions. EXPERIMENTS: The adsorption behavior of surfactant blends known to form complexes was investigated...
November 14, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29175547/zte-mri-in-high-magnetic-field-as-a-time-effective-3d-imaging-technique-for-monitoring-water-ingress-in-porous-rocks-at-sub-millimetre-resolution
#3
Władysław P Węglarz, Artur Krzyżak, Grzegorz Machowski, Michał Stefaniuk
Zero echo time magnetic resonance imaging (ZTE MRI) at 9.4T was used to assess the local distribution of water in dolomite rocks under different saturation conditions. The results were compared with the industry standard Single Point Imaging (SPI) at 0.6T. 3D maps of the local amount of water saturating heterogeneous rock were obtained from the imaging data, and correlated with the corresponding structural images from high resolution micro-CT (μCT). The method can be applicable in the investigation of spatial kinetics of water saturation processes in porous, heterogeneous rocks where imaging methods based on spin echo, such as RARE, have failed due to short T2, while SPI is often impractical due to its long acquisition time...
November 23, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/29135301/microbialite-biosignature-analysis-by-mesoscale-x-ray-fluorescence-%C3%AE-xrf-mapping
#4
Michael M Tice, Kimbra Quezergue, Michael C Pope
As part of its biosignature detection package, the Mars 2020 rover will carry PIXL, the Planetary Instrument for X-ray Lithochemistry, a spatially resolved X-ray fluorescence (μXRF) spectrometer. Understanding the types of biosignatures detectable by μXRF and the rock types μXRF is most effective at analyzing is therefore an important goal in preparation for in situ Mars 2020 science and sample selection. We tested mesoscale chemical mapping for biosignature interpretation in microbialites. In particular, we used μXRF to identify spatial distributions and associations between various elements ("fluorescence microfacies") to infer the physical, biological, and chemical processes that produced the observed compositional distributions...
November 2017: Astrobiology
https://www.readbyqxmd.com/read/29120499/evolution-of-the-subsurface-k-rich-brines-in-the-triassic-carbonates-in-the-sichuan-basin-of-china
#5
Xun Zhou, Xiaocui Wang, Jiajun Han, Qin Cao, Changlong Jiang, Juan Guo, Haiyan Zhou
Subsurface K-rich brines are important mineral resources for fertilizer production while the evolution of such brines is poorly documented. In the Sichuan Basin in southwest China, they are found mainly in the Middle and Lower Triassic marine carbonate aquifers. Total dissolved solids of the brines range from 176 to 378 g/L and K concentrations, from 1.9 to 53.3 g/L. We found that the brines are mainly of Cl-Na type, while Ba is absent in the brines. Comparison of the brine samples with both the trajectories of ions and the newly proposed trajectories of ion ratios of evaporated seawater suggests that the brines are enriched in Ca, Sr, Li, and I, depleted in SO4 and Mg, and neither enriched nor depleted in Cl and Na...
November 9, 2017: Ground Water
https://www.readbyqxmd.com/read/29079847/zebra-rocks-compaction-waves-create-ore-deposits
#6
Ulrich Kelka, Manolis Veveakis, Daniel Koehn, Nicolas Beaudoin
Nature has a range of distinct mechanisms that cause initially heterogeneous systems to break their symmetry and form patterns. One of these patterns is zebra dolomite that is frequently hosting economically important base metal mineralization. A consistent generic model for the genesis of these periodically banded rocks is still lacking. In this contribution, we present for the first time a fully consistent mathematical model for the genesis of the pattern by coupling the reactive fluid-solid system with hydromechanics...
October 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29018969/biomineralisation-of-carbonate-and-sulphate-by-the-halophilic-bacterium-halomonas-maura-at-different-manganese-concentrations
#7
Almudena Rivadeneyra, Alejandro Gonzalez-Martinez, Gabriela R Portela, Daniel J Martin-Ramos, Jesús Gonzalez-Lopez, María A Rivadeneyra
The ability of Halomonas maura to bioprecipitate carbonate and sulphate crystals in solid media at different manganese concentrations has been demonstrated in this study for the first time. The precipitated minerals were studied by X-ray diffraction, scanning and transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The precipitated minerals were different based on the manganese concentration present in the medium and the incubation time. In the absence of manganese, H. maura formed pseudokutnahorite crystals; in the presence of manganese, the concentration in the culture medium determined the precipitation carbonates, such as rhodochrosite and dolomites...
November 2017: Extremophiles: Life Under Extreme Conditions
https://www.readbyqxmd.com/read/28988088/low-temperature-geothermal-systems-in-carbonate-evaporitic-rocks-mineral-equilibria-assumptions-and-geothermometrical-calculations-insights-from-the-arnedillo-thermal-waters-spain
#8
Mónica Blasco, María J Gimeno, Luis F Auqué
Geothermometrical calculations in low-medium temperature geothermal systems hosted in carbonate-evaporitic rocks are complicated because 1) some of the classical chemical geothermometers are, usually, inadequate (since they were developed for higher temperature systems with different mineral-water equilibria at depth) and 2) the chemical geothermometers calibrated for these systems (based on the Ca and Mg or SO4 and F contents) are not free of problems either. The case study of the Arnedillo thermal system, a carbonate-evaporitic system of low temperature, will be used to deal with these problems through the combination of several geothermometrical techniques (chemical and isotopic geothermometers and geochemical modelling)...
February 15, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/28965179/chemical-characteristics-and-source-analysis-on-ionic-composition-of-rainwater-collected-in-the-carpathians-cold-pole-ciuc-basin-eastern-carpathians-romania
#9
Róbert Szép, Elena Mateescu, Aurelia Cristina Nechifor, Ágnes Keresztesi
A study of precipitation chemistry was conducted for 11 years (01 January 2006-31 December 2016) in the Ciuc basin, Eastern Carpathians, Romania. The studied area is an enclosed basin, also called "the Carpathians cold pole." All collected samples were analyzed for major cations and anions. HCO3(-) concentrations were calculated based on the empirical relationship between pH and HCO3(-). The multiannual arithmetic mean of pH values was found to be 6.57. The lowest and highest pH values were measured in 2009 and 2013, being 6...
October 1, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28858711/capture-and-recycling-of-ammonium-by-dolomite-aided-struvite-precipitation-and-thermolysis
#10
Liang Chen, Chun Hui Zhou, Hao Zhang, Dong Shen Tong, Wei Hua Yu, Hui Min Yang, Mao Quan Chu
The capture and reuse of NH4(+) is an ideal solution to treat NH4(+)-containing wastewater. The capture and reuse process needs to be clean and cost-effective. Currently, however, there are many obstacles, particularly in the availability, cost, and recovery of the chemical sources required. Here, we demonstrate a clean and efficient method to capture and recycle NH4(+) by a dolomite-aided struvite precipitation process. Dolomite calcined carefully in CO2 atmosphere was used as a Mg source to react with PO4(3-) (KH2PO4) and NH4(+) in model wastewater (2000 mg L(-1) NH4(+))...
August 13, 2017: Chemosphere
https://www.readbyqxmd.com/read/28812872/effect-of-mineral-dissolution-precipitation-and-co2-exsolution-on-co2-transport-in-geological-carbon-storage
#11
Ruina Xu, Rong Li, Jin Ma, Di He, Peixue Jiang
Geological carbon sequestration (GCS) in deep saline aquifers is an effective means for storing carbon dioxide to address global climate change. As the time after injection increases, the safety of storage increases as the CO2 transforms from a separate phase to CO2(aq) and HCO3(-) by dissolution and then to carbonates by mineral dissolution. However, subsequent depressurization could lead to dissolved CO2(aq) escaping from the formation water and creating a new separate phase which may reduce the GCS system safety...
August 16, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28795400/application-of-micro-ftir-mapping-and-sem-to-study-compositional-heterogeneity-of-siltstones-example-from-the-late-devonian-early-mississippian-middle-bakken-member
#12
C Gasaway, M Mastalerz, F Krause, C Clarkson, C Debuhr
This paper explores the applicability of micro-FTIR mapping to study heterogeneity of organic matter-lean siltstones. Closely spaced samples of Late Devonian dolomitic siltstones of the Middle Bakken Member were analysed with micro-FTIR, powder X-ray diffraction, and scanning electron microscopy (SEM) to explore the distribution and chemical properties of organic matter (OM), muscovite/feldspar/clay group, carbonates, and quartz, and their influence on porosity and permeability of these rocks. Our results show that quartz is the dominant component of the samples, and the main mineralogical differences between the samples are reflected in the abundance of carbonate minerals...
August 10, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28763288/particle-size-distribution-a-key-factor-in-estimating-powder-dustiness
#13
Ana López-Lilao, Forner Vicenta Sanfélix, Gasch Gustavo Mallol, Gimeno Eliseo Monfort
ASTRACT A wide variety of raw materials, involving more than twenty samples of quartzes, feldspars, nephelines, carbonates, dolomites, sands, zircons, and alumina, were selected and characterised. Dustiness, i.e. a materials' tendency to generate dust on handling, was determined using the continuous drop method. These raw materials were selected to encompass a wide range of particle sizes (1.6-294 µm) and true densities (2650-4680 kg/m(3)). The dustiness of the raw materials, i.e. their tendency to generate dust on handling, was determined using the continuous drop method...
August 1, 2017: Journal of Occupational and Environmental Hygiene
https://www.readbyqxmd.com/read/28757219/olivine-dolomite-and-ceramic-filters-in-one-vessel-to-produce-clean-gas-from-biomass
#14
Sergio Rapagnà, Katia Gallucci, Pier Ugo Foscolo
Heavy organic compounds produced during almond shells gasification in a steam and/or air atmosphere, usually called tar, are drastically reduced in the product gas by using simultaneously in one vessel a ceramic filter placed in the freeboard and a mixture of olivine and dolomite particles in the fluidized bed of the gasifier. The content of tar in the product gas during a reference gasification test with air, in presence of fresh olivine particles only, was 8600mg/Nm(3) of dry gas. By gasifying biomass with steam at the same temperature level of 820°C in a bed of olivine and dolomite (20% by weight), and in the presence of a catalytic ceramic filter inserted in the freeboard of the fluidized bed gasifier, the level of tar was brought down to 57mg/Nm(3) of dry producct gas, with a decrease of more than two orders of magnitude...
July 27, 2017: Waste Management
https://www.readbyqxmd.com/read/28738558/elemental-source-attribution-signatures-for-calcium-ammonium-nitrate-can-fertilizers-used-in-homemade-explosives
#15
Carlos G Fraga, Alexander V Mitroshkov, Nikhil S Mirjankar, Brian P Dockendorff, Angie M Melville
Calcium ammonium nitrate (CAN) is a widely available fertilizer composed of ammonium nitrate (AN) mixed with some form of calcium carbonate such as limestone or dolomite. CAN is also frequently used to make homemade explosives. The potential of using elemental profiling and chemometrics to match both pristine and reprocessed CAN fertilizers to their factories of origin for use in future forensic investigations was examined. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the concentrations of 64 elements in 125 samples from 11 CAN stocks from 6 different CAN factories...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28737010/carbonate-ooids-of-the-mesoarchaean-pongola-supergroup-south-africa
#16
M Siahi, A Hofmann, S Master, C W Mueller, A Gerdes
Ooids from the Mesoarchaean Chobeni Formation, Pongola Supergroup, KwaZulu-Natal, South Africa are older than any ooids reported to date. They are made of dolomite and ankerite and show concentric, radial-concentric, micritic, and radial fabrics. Radial ooids are interpreted to have originated from high-Mg-calcite and probably formed by microbial activity in a low-energy regime, while concentric ooids had an aragonite precursor and formed biotically under agitated/high-energy environmental conditions. Micritic ooids formed via the recrystallization of concentric ooids...
July 24, 2017: Geobiology
https://www.readbyqxmd.com/read/28735325/characterization-of-endolithic-culturable-microbial-communities-in-carbonate-rocks-from-a-typical-karst-canyon-in-guizhou-china
#17
Yuan Tang, Jian-Zhong Cheng, Bin Lian
The endolithic environment is a ubiquitous habitat for microorganisms and a critical interface between biology and geology. In this study, a culture-based method and the phylogenetic analysis based on 16S rRNA and internal transcribed spacer (ITS) sequences were used to investigate the diversity of endolithic bacteria and fungi in two main types of carbonate rocks (namely dolomite and limestone) from Nanjiang Canyon in Guizhou karst area, China. The results of bacterial diversity indicated that all bacteria isolated from dolomite and limestone rocks were divided into 4 bacterial groups, including Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes...
January 2, 2017: Polish Journal of Microbiology
https://www.readbyqxmd.com/read/28735089/biodeterioration-of-marble-in-an-underwater-environment
#18
Beatriz Cámara, Mónica Álvarez de Buergo, Manuel Bethencourt, Tomás Fernández-Montblanc, Mauro F La Russa, Michela Ricca, Rafael Fort
This study examines the deterioration of geomaterials used throughout history that today may be found lying on the ocean floor. Submerged archaeological sites including cargoes from shipwrecks or ancient city ruins have been a topic of interest from a perspective of in situ musealization, as a way of making underwater cultural heritage accessible to the public. In an experimental study conducted at an underwater archaeological site in the Bay of Cádiz (SW Spain), we subjected two types of marble (Carrara and Macael) to three conditions to which submerged archaeological objects are often exposed: full exposure to the water column, natural processes of burial and unearthing, or permanent burial...
December 31, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28711248/the-effect-of-source-of-supplemental-dietary-calcium-and-magnesium-in-the-peripartum-period-and-level-of-dietary-magnesium-postpartum-on-mineral-status-performance-and-energy-metabolites-in-multiparous-holstein-cows
#19
B M Leno, S E LaCount, C M Ryan, D Briggs, M Crombie, T R Overton
The objective of this study was to determine the effects of feeding different supplemental sources of Ca and Mg in the peripartum period, and different dietary levels of Mg postpartum, on plasma mineral status, performance, and aspects of energy metabolism in transition dairy cows. Multiparous Holstein cows (n = 41) were used in a completely randomized design with a 2 × 2 factorial arrangement of treatments starting at 28 d before expected parturition. Main effects were source assignments (CS = common sources of supplemental Ca and Mg, or MA = a blend of common and commercial mineral sources with supplemental minerals primarily from a commercial Ca-Mg dolomite source; MIN-AD, Papillon Agricultural Company Inc...
September 2017: Journal of Dairy Science
https://www.readbyqxmd.com/read/28691279/paleoecology-of-neoproterozoic-hypersaline-environments-biomarker-evidence-for-haloarchaea-methanogens-and-cyanobacteria
#20
R Schinteie, J J Brocks
While numerous studies have examined modern hypersaline ecosystems, their equivalents in the geologic past, particularly in the Precambrian, are poorly understood. In this study, biomarkers from ~820 million year (Ma)-old evaporites from the Gillen Formation of the mid-Neoproterozoic Bitter Springs Group, central Australia, are investigated to elucidate the antiquity and paleoecology of halophiles. The sediments were composed of alternating laminae of dolomitized microbial mats and up to 90% anhydrite. Solvent extraction of these samples yielded thermally well-preserved hydrocarbon biomarkers...
September 2017: Geobiology
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