Field-based accounting of CO2sequestration in ultramafic mine wastes using portable X-ray diffraction

Assessing the viability of portable Raman spectroscopy for determining the geological source of obsidian

The carbonation of ultramafic rocks, including tailings from ultramafic-hosted ore deposits, can be used to remove CO2 from the atmosphere and store it safely within minerals over geologic timescales. Quantitative X-ray diffraction (XRD) using Rietveld refinements can be employed to estimate the amount of carbon sequestered by carbonate minerals that form as a result of weathering of ultramafic rocks. However, the presence of structurally disordered phases such as serpentine minerals, which are common in ultramafic ore bodies such as at the Woodsreef chrysotile mine (New South Wales, Australia), results in samples that cannot be analyzed using typical Rietveld refinement strategies. Previous investigations of carbon sequestration at Woodsreef and other ultramafic mine sites typically used modified Rietveld refinement methods that apply structureless pattern fitting for disordered phases; however, no detailed comparison of the accuracy (or precision) of these methods for carbon accounting has yet been attempted, making it difficult to determine the most appropriate analysis method. Such an analysis would need to test whether some methods more accurately quantify the abundances of certain minerals, such as pyroaurite [Mg6Fe23+(CO3)(OH)(16)center dot 4H(2)O] and other hydrotalcite group minerals, which suffer from severe preferred orientation and may play an important role in carbon sequestration at some mines. Here, we assess and compare the accuracy, and to a lesser extent the precision, of three different non-traditional Rietveld refinement methods for carbon accounting: (1) the PONKCS method, (2) the combined use of a Pawley fit for serpentine minerals and an internal standard (Pawley/internal standard method), and (3) the combined use of PONKCS and Pawley/internal standard methods. We examine which of these approaches represents the most accurate way to quantify the abundances of serpentine, pyroaurite, and other carbonate-bearing phases in a given sample. We demonstrate that by combining the PONKCS and Pawley/internal standard methods it is possible to quantify the abundances of disordered phases in a sample and to obtain an estimate of the amorphous content and any unaccounted intensity in an XRD pattern. Eight artificial tailings samples with known mineralogical compositions were prepared to reflect the natural variation found within the tailings at the Woodsreef chrysotile mine. Rietveld refinement results for the three methods were compared with the known compositions of each sample to calculate absolute and relative error values and to evaluate the accuracy of the three methods, including whether they produce systematic under- or overestimates of mineral abundance. Estimated standard deviations were also calculated during refinements; these values, which are a measure of precision, were not strongly affected by the choice of refinement method. The abundance of serpentine minerals is, however, systematically overestimated when using the PONKCS and Pawley/internal standard methods, and the abundances of minor phases (<10 wt%) are systematically underestimated using all three methods. Refined abundances for pyroaurite were found to be increasingly susceptible to error with increasing abundance, with an underestimation of 6.6 wt% absolute (60.6% relative) for a sample containing 10 9 wt% pyroaurite.These significant errors are due to difficulties in mitigating preferred orientation of hydrotalcite minerals during sample preparation as well as modeling its effects on XRD patterns. The abundances of hydromagnesite [Mg,(CO3)(4)(OH)(2)center dot 4H(2)O], another important host for atmospheric CO2 during weathering of ultramafic rocks, was consistently underestimated by all three methods, with the highest underestimation being 3.7 wt% absolute (or 25.0% relative) for a sample containing 15.0 wt% hydromagnesite. Overall, the Pawley/internal standard method produced more accurate results than the PONKCS method, with an average bias per refinement of 6.7 wt%, compared with 10.3 wt% using PONKCS and 12.9 wt% for the combined PONKCS-Pawley/internal standard method. Furthermore, the values for the refined abundance of hydromagnesite obtained from refinements using the Pawley/internal standard method were significantly more accurate than those for refinements done with the PONKCS method, with relative errors typically <25% for hydromagnesite abundances between 5 and 15 wt%. The simpler and faster sample preparation makes the PONKCS method well-suited for rapid carbon accounting, for instance in the field using a portable XRD; however, the superior accuracy gained when using an internal standard make the Pawley/internal standard method the preferable means of undertaking a detailed laboratory-based study. As all three methods displayed an underestimation of carbonate phases, applying these methods to natural samples will likely produce an underestimate of hydromagnesite and hydrotalcite group mineral abundances. As such, crystallographic accounting strategies that use modified Rietveld refinement methods produce a conservative estimate of the carbon sequestered in minerals.

GeoRaman is an international conference where researchers gather to discuss the application of Raman spectroscopy in the fields of geological, planetary, and archaeological sciences. Historically, the first GeoRaman conference was held in Paris (France) in 1986, and then continued there for some time. After a stint in France, the conference then moved to Valladolid (Spain) in 1999, and then took a wide international journey to Prague (Czech Republic) in 2002, to Hawaii (USA) in 2004, to Almunecar (Spain) in 2006, to Gent (Belgium) in 2008, to Sydney (Australia) in 2010, and then back to Nancy (France) in 2012. For the first time, this conference was held in the continental United States, in St. Louis, Missouri, from 15 to 19 of June 2014. Researchers from over 18 countries attended. GeoRaman XI in St. Louis focused on two major aspects of Raman spectroscopy: (1) the most advanced technologies and instrumentation, from laboratories to a wide variety of field applications, e.g. industrial and security monitoring, geo-fields, deep ocean, and on other planets and (2) the newest applications in studying inorganic, organic, and bio-genetic materials in Earth Sciences, Planetary Sciences, Environmental Science, Forensic Science, Archaeology and Archaeometry, Gemology, and Astrobiology. This special issue of the Journal of Raman spectroscopy dedicated to the 11th International GeoRaman Conference has 31 papers covering areas such as Planetary Science, Astrobiology, Mineralogy and Petrology, Biomineralization, Fluid Inclusions, Archaeology and Archaeometry, and Environmental Science. Several of the papers in this special issue are related to the application of Raman spectroscopy as an instrument for planetary exploration. Wei et al.1 report the first rover test of a Raman spectrometer specifically developed for mission flights, the Mars Micro-beam Raman Spectrometer in the Atacama Desert (Chile). In this work, they discovered γ-anhydrite, which is typically an unstable mineral, in large quantities in the soils of the Atacama Desert. Lui and Wang2 shed light on the dehydration of Na-jarosite, ferricopiapite, and rhomboclase to understand their formation and presence as ferric sulfates on Mars. This paper can be found here http://onlinelibrary.wiley.com/store/10.1002/jrs.4655/asset/jrs4655.pdf. Uriarte et al.3 work on collecting reference spectra of CaCl2.nH2O (n = 0, 2, 4, 6) to enable the geochemical community to identify these key minerals in important fluid geochemical processes here on Earth and Mars. Wang et al.4 provide the first systematic Raman spectroscopic study of phyllosilicates of planetary science importance for the characterization of such materials on the surface of Mars. Bathgate et al.5 identify by Raman spectroscopy primary and secondary minerals of volcanic rock weathering and alteration as a database for upcoming future exploration of Mars. This special issue contains a number of papers detailing the application of Raman spectroscopy to detect chemical traces of life on Mars. Fernandes et al.6 elucidate the pigment chemistry of three lichens of astrobiological relevance. They report the first identification of parietin in these lichens, which this pigment is effective in protecting the organism from free radicals and ultraviolet radiation. The paper can be found here http://onlinelibrary.wiley.com/store/10.1002/jrs.4626/asset/jrs4626.pdf Hooijschuur et al.7 investigate the effects of photodegradation of carotenoids within bacterial cell membranes and calcite. They report that carotenoids residing in the bacterial membranes were less sensitive to photodegradation than the mineral matrix. Harris et al.8 investigated several terrestrial Mars analogue samples to point out a cautionary tale to the astrobiology community potential for confusion in interpreting Raman spectra acquired from these types of samples. Foucher et al.9 demonstrates the potential of Raman mapping of the distribution and change in intensity ratio of the D and G bands arising from carbonaceous material as a biosignature to help identify potential fossilized microbes here in early Earth rocks and Mars. Several of the papers in this special issue are on the application of Raman spectroscopy to problems in mineralogy and petrology. Korsakov et al.10 undertook Confocal two-dimensional and three-dimensional Raman imaging of the Kokchetav metamorphic diamonds from different rock types which these results showed that those various diamonds had different crystal quality with complex internal morphologies associated with defects. The paper by Bartholomew et al.11 investigates the potential of Raman spectroscopy as the number one instrument for mineral identification in the Geosciences. They quantify the range of Raman intensities that can be expected from natural mineral samples and investigate the incorporation of this information into instrument standards and analytical methodology to design data collection strategies across Geoscience laboratories. Carey et al.12 apply machine learning techniques in order to improve mineral identification obtained by Raman spectroscopy. Golovin et al.13 show that the carbonate mineral zemkorite is not likely stable at the Earth's surface but will transform into the more stable polymorph nyerereite at these P-T conditions. Gomez-Nubla et al.14 characterized impact glass formed by meteorite impacts. They show that a substantial degree of post-impact terrestrial weathering can occur in these materials, which needs to be taken under consideration. Frost et al.15 use vibrational spectroscopy to characterize the mineral tangdanite and show that this mineral contains arsenate and sulfate polyhedra. Jehlicka and Vandenabeele16 evaluate portable Raman instruments to investigate the best excitation wavelength in collection of spectra from zeolite and beryllium containing silicate minerals. This work recommends using the portable NIR 785 nm system for the collection of better quality spectra on these materials. Cathelineau et al.17 use Raman spectroscopy to better understand the crystal structure of the economically important Ni-ore talc-like mineral phases, revealing that Raman spectroscopy can quickly evaluate the Ni content in these important economic minerals. Burlet and Vandrabant18 shed light on the structure of economically important manganese oxide minerals lithiophorite and asbolane that are typically difficult to characterize by traditional X-ray diffraction. Lopez and Frost19 shed light on the mineral responsible for the coloration of black marble from a quarry in Chillagoe, North Queensland, Australia. Petriglieri et al.20 use Raman mapping to identify small-scale changes in serpentine mineralogy to enable a greater understanding of the serpentinization process. Moroz et al.21 delineate the best wavelength of laser excitation to collect fluorescence free spectra on thermally immature carbonaceous materials. They clearly demonstrate that the laser excitation wavelength at 325 nm yields the best quality spectra that can be collected from these materials. This was a new session organized at GeoRaman, and while we only have one paper for the special issue, this field is opening up for the application of Raman spectroscopy and should grow enormously in the near future. Bioapatite, a carbonated, hydroxylated calcium phosphate salt, undergoes phase changes during heating. However, these changes are somewhat unclear; Li et al.22 elucidated these thermal transformations using Raman spectroscopy to study various heated material. They observed that the mineral undergoes de-carbonation and recrystallization at relatively low temperatures. This special issue contains a number of papers on fluid inclusions, which have contributed greatly to our understanding of measuring salinity and gaseous phases. Caumon et al.23 shed light on the role of mineral birefringence and on the polarization properties of the O–H stretching band of liquid water for determining the salinity of aqueous fluid inclusions. Tarantola and Caumon24 revealed that salinity measurements in fluid inclusions were overestimated by 1% per 10–15 MPa of negative pressure, thus allowing a way forward to determine the salinity of metastable fluid inclusions by Raman spectroscopy. Li and Chou25 analyze silicate melt inclusions in quartz from granites within pegmatite deposits by Raman spectroscopy revealing for the first time the occurrence of H2 in the vapor phase of the inclusion. Chou26 calibrated the Raman shifts of cyclohexane with the goal of using this calibration to accurately determine the ν1 CH4 band position to calculate CH4 densities in fluid inclusions. Several papers in this special issue are devoted to Archaeology and Archaeometry. Barone et al.27 obtain Raman spectra using portable instruments on an archaeologically significant jewelry museum collection dated to the 17th–18th centuries in order to verify previous identification of the gems in the collection made by conservators. Cianchetta et al.28 used Raman spectroscopy to investigate the process used in the red and black coloring of Athenian pottery. They showed for the first time that these ancient materials were produced using at least two separate firings. Coccato et al.29 investigate carbon black pigments in works of art to elucidate the various sources and origins of different carbons used as artwork color pigments. Rousaki et al.30 analyzed the pigment composition of hunter-gathered archaeological samples from Northern Patagonia. Their work demonstrates these ancient people used clay-like materials rather than the usual hematite as a pigment agent. Belgodere et al.31 determine diffusion coefficients of dissolved carbon dioxide in varying salinities to predict the transport of dissolved gases in sedimentary sequences for mitigation of green house gas emissions. The 31 papers in this special issue dedicated to the 11th International GeoRaman Conference have expanded our understanding in a diverse range of fields. For example, the interaction of geological fluids and their measurement, elucidation of biological activity in recent and ancient environments here on Earth, astrobiological prospecting for life on Mars, thermal transformation of biologically precipitated minerals, mineral stability at the surface of the Earth, structure of economically important minerals, Raman spectroscopy as major tool for mineral identification, and pigment chemistry used in art and cultural artifacts. Given the enthusiasm and quest for knowledge in the GeoRaman community, together with the development of new Raman techniques, the future GeoRaman conferences should continue to generate exciting new research in the Earth Sciences. I would like to thank all the delegates, presenters, and conference assistants (providing great help in the background), the local organizing committee, the international science advisory committee, and Washington University in St. Louis for a wonderful venue. I am extremely grateful to the following companies and institutions that supported this conference: Washington University in St. Louis, Department of Earth and Planetary Sciences, McDonnell Center for Space Sciences, Universities Space Research Association, Lunar and Planetary Institute, Renishaw, WiTec, ThermoFisher Scientific, Andor, Bruker, BWTEK, GemLab Group, Horiba Scientific, Kaiser Optical System, Inc., Ondax, RPMC, SciAps, and R. H. Minerals. Special thanks to the Editor-in-Chief of the Journal of Raman Spectroscopy, Dr Larry Nafie, for making this special issue possible, and of course, to all the authors and reviewers of the manuscripts for their invaluable contribution. It was a pleasure and honor to serve as the guest editor for this diverse collection of papers, and I am looking forward to seeing you at the next GeoRaman conference in Novosibirsk, Russia in 2016!

Atmospheric carbon dioxide has been increased and was reached approximately to 390 mg/L at December 2010 (Tans, 2011). Rising trend of carbon dioxide in past and present time may be an indicator capable of estimating the concentration of atmospheric carbon dioxide in the future. Cause for increase of atmospheric carbon dioxide was already investigated and became general knowledge for the civilized peoples who are watching TV, listening to radio, and reading newspapers. Anybody of the civilized peoples can anticipate that the atmospheric carbon dioxide is increased continuously until unknowable time in the future but not in the near future. Carbon dioxide is believed to be a major factor affecting global climate variation because increase of atmospheric carbon dioxide is proportional to variation trend of global average temperature (Cox et al., 2000). Atmospheric carbon dioxide is generated naturally from the eruption of volcano (Gerlach et al., 2002; Williams et al., 1992), decay of organic matters, respiration of animals, and cellular respiration of microorganisms (Raich and Schlesinger, 2002; Van Veen et al., 1991); meanwhile, artificially from combustion of fossil fuels, combustion of organic matters, and cement making-process (Worrell et al., 2001). Theoretically, the natural atmospheric carbon dioxide generated biologically from the decay of organic matter and the respirations of organisms has to be fixed biologically by land plants, aquatic plants, and photosynthetic microorganisms, by which cycle of atmospheric carbon dioxide may be nearly balanced (Grulke et al., 1990). All of the human-emitted carbon dioxide except the naturally balanced one may be incorporated newly into the pool of atmospheric greenhouse gases that are methane, water vapor, fluorocarbons, nitrous oxide, and carbon dioxide (Lashof and Ahuja, 1990). The airborne fraction of carbon dioxide that is the ratio of the increase in atmospheric carbon dioxide to the emitted carbon dioxide variation was typically about 45% over 5 years period (Keeling et al., 1995). Canadell at al (2007) reported that about 57% of human-emitted carbon dioxide was removed by the biosphere and oceans. These reports indicate that the airborne fraction of carbon dioxide is at least 43-45%, which may be the balance emitted by human activity. The land plants are the largest natural carbon dioxide sinker, which have been decreased globally by deforestation (Cramer et al., 2004). Especially, tropical and rainforests are being

Effects of fuel and forest conservation on future levels of atmospheric carbon dioxide

Effects of fuel and forest conservation on future levels of atmospheric carbon dioxide

Grass attack

Remote sensing of the atmospheric greenhouse gases, methane (CH4) and carbon dioxide (CO2), contributes to the understanding of global warming and climate change. A portable ground-based instrument consisting of a commercially available desktop optical spectrum analyzer and a small sun tracker has been applied to measure the column densities of atmospheric CH4 and CO2 at Yanting observation station in a mountainous paddy field of the Sichuan Basin from September to November 2013. The column-averaged dry-air molar mixing ratios, XCH4/XCO2, are compared with those retrieved by satellite observations in the Sichuan Basin and by ground-based network observations in the same latitude zone as the Yanting observation station.

A multi-analyte platform based on a portable instrument is presented that enables oxygen and carbon dioxide to be determined in sample gases. The use of four sensing channels (two channels for each analyte to provide redundancy) warrants high system reliability. The sensing scheme in case of oxygen is based on the quenching of the phosphorescence of the platinum octaethylporphyrin complex. In case of carbon dioxide, a secondary inner-filter effect is exploited that is caused by a pH indicator whose color is reversibly changed. The sensing membranes were placed directly on the detectors and on the light sources so to make additional optical element dispensable, reduce system costs, avoid problems related to optical alignment, optimize the efficiency of data acquisition, and enable facile replacement of sensors. The resulting microcontroller-based system is immune against optical and electrical interferences, contains simple digital signal processing circuitry, and has low power consumption. The response of the system to the two gases was modeled, and calibration curves are corrected for effects of temperature. The instrument was characterized in terms of cross-sensitivity and dynamic response. It can determine oxygen and carbon dioxide in terms of volume percentage.

Rhizosphere-induced changes of Pinus densiflora (S. and Z.) grown at elevated atmospheric temperature and carbon dioxide are presented based on experiments carried out in a two-compartment rhizobag system filled with forest soil in an environmentally controlled walk-in chamber with four treatment combinations: control (25°C, 500 μmol mol−1 CO2), T2 (30°C, 500 μmol mol−1 CO2), T3 (25°C, 800 μmol mol−1 CO2), and T4 (30°C, 800 μmol mol−1 CO2). Elevated temperature and atmospheric carbon dioxide resulted in higher concentration of sugars and dissolved organic carbon in soil solution, especially at the later period of plant growth. Soil solution pH from the rhizosphere became less acidic than the bulk soil regardless of treatment, while the electrical conductivity of soil solution from the rhizosphere was increased by elevated carbon dioxide treatment. Biolog EcoPlate™ data showed that the rhizosphere had higher average well color development, Shannon–Weaver index, and richness of carbon utilization compared with bulk soil, indicating that microbial activity in the rhizosphere was higher and more diverse than in bulk soil. Subsequent principal component analysis indicated separation of soil microbial community functional structures in the rhizosphere by treatment. The principal components extracted were correlated to plant-induced changes of substrate quality and quantity in the rhizosphere as plants' response to varying temperature and atmospheric carbon dioxide.

The article studies the volume of CO2 emissions by cement enterprises in Western Europe. The review of the existing cement enterprises of the countries of the studied region is carried out. The aim the study is to assess the emissions of cement industries in Western Europe and the possibility of their use for the production nanomaterials. The analysis the dynamics of changes in the total annual carbon dioxide emissions for the period 1960-2020 was carried out on the basis of data from the open source Global Carbon Atlas, funded by Fondation BNP Paribus. Diagrams changes in the studied indicator for European countries are constructed. Countries with trends of decreasing and increasing the level of annual carbon dioxide emissions have been identified. A statistical assessment of CO2 emissions by European cement enterprises has been carried out and countries with an identical regime of CO2 emissions into the atmospheric air have been identified. The assessment the technological process of production nanofibers based on atmospheric carbon dioxide in various European countries has been carried out. Keywords: climate; carbon dioxide; carbon nanofiber; statistical analysis; cement production.

Annual CO2 emissions (in 1000 Mt) %

An investigation of carbon dioxide partial pressures in the atmosphere and surface ocean conducted as part of a cooperative study under the general sponsorship of the International Geophysical Year is summarized. Results are given for about 470 hours of air analyses and 200 individual surface ocean water measurements made from 1957 to 1959 between 60°N and 58°S. Over the Atlantic Ocean, the atmospheric carbon dioxide concentration is found to average 316 ppm by volume and to be quite uniform except for a minor increase toward the equator. The total carbon dioxide in the earth's atmosphere is estimated to be 2.41×1018g. In the equatorial region, the partial pressure of carbon dioxide appears to be higher in the surface water than in the atmosphere; in the higher latitudes it appears to be lower.

Changing atmospheric composition is the primary driving force behind most aspects global climate change. In this chapter, we focus on field‐portable FTIR measurement techniques for four of the most abundant and important trace gases – carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O) and carbon monoxide (CO). There are two themes: applications of FTIR spectrometry for high precision in situ measurements of CO 2 , CH 4 , N 2 O and CO in relatively clean air, and remote sensing of atmospheric composition by ground‐based high resolution solar FTIR spectroscopy. Portable instruments and methods suited to high precision field measurements of trace gas composition are described, followed by several approaches to the measurement of rates of emission and exchange of these trace gases with sources and sinks at the earth’s surface. Ground based remote sensing by high resolution solar absorption spectroscopy is also described.

The heat of immersion of Zeolite (Molecular Sieve-13X) in water was experimentally found to increase with its degassing temperature and to have a maximum peak at about 300°C. The acidity of Zeolite measured by n-butylamine titration also showed a similar peak at 300°C. But the heat of immersion of Zeolite in benzene showed a definite value above 200°C. It was found that though physically absorbed water or structral water may be remove at lower degassing temperature, further desorption of water and surface changes occurred above 300°C.Magnesia showed a higher heat of immersion when ground in the atmospheres of dry air and carbon dioxide. The activation of the Magnesia surface was mainly caused by the distorted surface layer, i. e., the plastic flow of the surface. From the infra-red spectra, carbon dioxide was detected on the Magnesia surfaces which were ground in the atmosphere of carbon dioxide. In this case, the surface activation by grinding was caused by the formation of an electro-static field by the chemisorbed carbon dioxide, as well as by the distortion of the surface layer.