ORCID Profile
0000-0002-0858-6902
Current Organisations
Klaipėda University
,
University of Alberta
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Mineralogy and Crystallography | Surface Processes | Inorganic Geochemistry | Geology not elsewhere classified | Geochemistry | Materials Engineering | Metals and Alloy Materials
Climate Change Mitigation Strategies | Expanding Knowledge in the Physical Sciences | Environmentally Sustainable Manufacturing not elsewhere classified | Physical and Chemical Conditions of Water in Coastal and Estuarine Environments |
Publisher: Mineralogical Society of America
Date: 06-2017
DOI: 10.2138/AM-2017-5953
Publisher: Elsevier BV
Date: 10-2015
Publisher: American Society of Civil Engineers (ASCE)
Date: 05-2014
Publisher: Elsevier BV
Date: 12-2018
Publisher: Wiley
Date: 03-12-2020
DOI: 10.1111/SED.12807
Abstract: Bioturbating organisms contribute significantly to elemental cycling in sediments through burrowing, grazing, organic matter and altering porewater chemical conditions. In the process, organisms are known to produce copious amounts of faecal material at high rates, sometimes in excess of 1 000 000 kg day −1 in a 1 km 2 area. Material from three organisms ( Arenicola marina , Callichirus major and Diopatra cuprea ) was collected from two locations, Raccoon Key and Steamboat Pass, in the Ogeechee River estuary, Georgia, USA, to explore how faecal production affects organic carbon cycling and clay mineralogies. The in idual organisms’ feeding strategies played a strong role in the extent to which they concentrate organic matter and lead to the formation of clay minerals. The faecal material of filter feeding Diopatra cuprea and selective deposit feeding Callichirus major contains up 45.8% and 47.3% kaolinite, respectively, while kaolinite is below detection limits in the surrounding matrix. By contrast, the non‐selective deposit‐feeder Arenicola marina does not appear to form or concentrate clay minerals. Callichirus major increases organic carbon contents at Raccoon Key by 68‐fold and Diopatra cuprea increases total organic carbon (w/w%) by 119‐fold and 32‐fold at Raccoon Key and Steamboat Pass, respectively. Arenicola marina , in contrast, does not noticeably concentrate organic matter in its faecal material, most likely as a consequence of non‐selective deposit‐feeding. Potentiometric titration data was used to explore surface reactivity and metal sorption. Diopatra cuprea and Callichirus major faecal material has strong metal binding affinities relative to the surrounding matrix, thereby increasing the potential for trace metals to be sequestered into the sedimentary record. The widespread occurrence of invertebrate faecal material enriched in clay minerals and organic matter likely has a significant influence on organic matter, grain size and trace metal distribution in estuarine sediments.
Publisher: Elsevier BV
Date: 12-2009
Publisher: American Geophysical Union (AGU)
Date: 09-2011
DOI: 10.1029/2011JE003853
Abstract: Smectites and hydrated Mg sulfate minerals have been identified in close association at various locations on the Martian surface. The hydration states of sulfates and smectites are dependent on temperature and relative humidity (RH), and therefore these minerals have the potential to affect cycling and bioavailability of H 2 O on Mars. We have conducted X‐ray powder diffraction experiments to investigate cycling of H 2 O within mixtures of Ca‐bearing smectites and hydrated Mg sulfate minerals under conditions of varying RH similar to those that exist at or just beneath the Martian surface. Our experiments show that under conditions of varying RH, cation‐exchange reactions occur between these two potential components of the Martian regolith, producing gypsum [CaSO 4 ·2H 2 O] and bassanite [CaSO 4 ·∼0.5H 2 O] in the absence of free‐liquid H 2 O. Cation‐exchange reactions were accompanied by significant loss of porosity, warping of the s le surface and, in some cases, volume expansion. The formation of Ca sulfate minerals in these experiments provides evidence for the development of thin films of H 2 O at mineral surfaces and suggests that similar processes may operate at the arid surface of Mars. Humidity‐driven cation‐exchange reactions between smectites and hydrated Mg sulfate minerals may therefore play a role in shaping the present‐day Martian surface and could have provided a transient source of H 2 O and nutrients (e.g., major and trace elements and possibly organic micro/macronutrients) for putative microorganisms.
Publisher: American Society of Civil Engineers (ASCE)
Date: 2016
Publisher: American Society of Civil Engineers (ASCE)
Date: 2016
Publisher: Elsevier BV
Date: 03-2009
Publisher: Mineralogical Society of America
Date: 11-2018
Publisher: Society of Economic Geologists
Date: 2009
Publisher: Elsevier BV
Date: 07-2017
Publisher: Elsevier BV
Date: 08-2015
Publisher: MDPI AG
Date: 12-10-2017
DOI: 10.3390/MIN7100191
Publisher: Pensoft Publishers
Date: 04-2019
DOI: 10.3897/NEOBIOTA.44.31650
Abstract: Standardized tools are needed to identify and prioritize the most harmful non-native species (NNS). A plethora of assessment protocols have been developed to evaluate the current and potential impacts of non-native species, but consistency among them has received limited attention. To estimate the consistency across impact assessment protocols, 89 specialists in biological invasions used 11 protocols to screen 57 NNS (2614 assessments). We tested if the consistency in the impact scoring across assessors, quantified as the coefficient of variation (CV), was dependent on the characteristics of the protocol, the taxonomic group and the expertise of the assessor. Mean CV across assessors was 40%, with a maximum of 223%. CV was lower for protocols with a low number of score levels, which demanded high levels of expertise, and when the assessors had greater expertise on the assessed species. The similarity among protocols with respect to the final scores was higher when the protocols considered the same impact types. We conclude that all protocols led to considerable inconsistency among assessors. In order to improve consistency, we highlight the importance of selecting assessors with high expertise, providing clear guidelines and adequate training but also deriving final decisions collaboratively by consensus.
Publisher: Springer Science and Business Media LLC
Date: 28-05-2018
Publisher: Elsevier BV
Date: 09-2018
Publisher: Wiley
Date: 05-2012
DOI: 10.2136/VZJ2011.0053
Publisher: Elsevier BV
Date: 06-2021
Publisher: Elsevier BV
Date: 11-2013
Publisher: Mineralogical Society of America
Date: 04-2013
Publisher: Elsevier BV
Date: 03-2022
Publisher: American Chemical Society (ACS)
Date: 20-08-2011
DOI: 10.1021/ES202112Y
Abstract: The mineral waste from some mines has the capacity to trap and store CO(2) within secondary carbonate minerals via the process of silicate weathering. Nesquehonite [MgCO(3)·3H(2)O] forms by weathering of Mg-silicate minerals in kimberlitic mine tailings at the Diavik Diamond Mine, Northwest Territories, Canada. Less abundant Na- and Ca-carbonate minerals precipitate from sewage treatment effluent deposited in the tailings storage facility. Radiocarbon and stable carbon and oxygen isotopes are used to assess the ability of mine tailings to trap and store modern CO(2) within these minerals in the arid, subarctic climate at Diavik. Stable isotopic data cannot always uniquely identify the source of carbon stored within minerals in this setting however, radiocarbon isotopic data provide a reliable quantitative estimate for sequestration of modern carbon. At least 89% of the carbon trapped within secondary carbonate minerals at Diavik is derived from a modern source, either by direct uptake of atmospheric CO(2) or indirect uptake though the biosphere. Silicate weathering at Diavik is trapping 102-114 g C/m(2)/y within nesquehonite, which corresponds to a 2 orders of magnitude increase over the background rate of CO(2) uptake predicted from arctic and subarctic river catchment data.
Publisher: Elsevier BV
Date: 09-2017
Publisher: Proceedings of the National Academy of Sciences
Date: 28-02-2011
Publisher: Elsevier BV
Date: 06-2014
Publisher: Elsevier BV
Date: 02-2020
Publisher: Elsevier BV
Date: 10-2017
Publisher: American Chemical Society (ACS)
Date: 09-06-2015
Abstract: We use in situ high-temperature X-ray diffraction (HT-XRD), ex-situ XRD and synchrotron X-ray absorption near edge structure spectroscopy (XANES) to derive fundamental insights into mechanisms of chromium oxidation during combustion of solid fuels. To mimic the real combustion environment, mixtures of pure eskolaite (Cr(3+)2O3), lime (CaO) and/or kaolinite [Al2Si2O5(OH)4] have been annealed at 600-1200 °C in air versus 1% O2 diluted by N2. Our results confirm for the first time that (1) the optimum temperature for Cr(6+) formation is 800 °C for the coexistence of lime and eskolaite (2) upon addition of kaolinite into oxide mixture, the temperature required to produce chromatite shifts to 1000 °C with a remarkable reduction in the fraction of Cr(6+). Beyond 1000 °C, transient phases are formed that bear Cr in intermediate valence states, which convert to different species other than Cr(6+) in the cooling stage (3) of significance to Cr mobility from the waste products generated by combustion, chromatite formed at >1000 °C has a glassy disposition that prevents its water-based leaching and (4) Increasing temperature facilitates the migration of eskolaite particles into bulk lime and enhances the extent to which Cr(3+) is oxidized, thereby completing the oxidation of Cr(3+) to Cr(6+) within 10 min.
Publisher: American Geophysical Union (AGU)
Date: 05-2021
DOI: 10.1029/2020JB021422
Abstract: Recent experimental studies have demonstrated that clay minerals (e.g., kaolinite, illite, and montmorillonite) have higher affinities for some trace elements under acidic versus alkaline conditions. This suggests that clays might be important vectors in the transport of trace elements from sites of acidic chemical weathering on land to marine depositional environments. To determine if clays behave similarly in nature, we collected water and mud (consisting of 38.5%–61.1% of kaolinite and montmorillonite) s les from boiling, low‐pH, mud pools venting at the El Tatio Geyser Field (ETGF) in Chile. Based on elemental abundances in the aqueous/solid phases, we observed that mud s les collected from lower pH pools (e.g., pH = 2.42 and 3.55) have high concentration factors for anionic elements (e.g., P and As) but low concentration factors for cationic elements (e.g., Ca, Mn, and Sr), while mud s les from higher pH pools (e.g., pH = 4.87 and 5.84) display the opposite trend. Acid‐base leaching experiments further reveal that increasing solution pH (to reflect downstream transport) led to the release of As and P from the mud surfaces due to increasingly negative surface charge, while decreasing pH (to determine the effects of re‐acidification) released Li, Ca, Co, Sr, Mo, and Cd. Our study confirms previous experimental findings that demonstrate clay minerals can assemble a erse inventory of trace elements during acid weathering (e.g., As) but then liberate them back into the aqueous phase as aqueous pH increases. Importantly, these observations provide a mechanism to account for the previous observations of regional As contamination in rivers downstream of the ETGF.
Publisher: American Geophysical Union (AGU)
Date: 07-2019
DOI: 10.1029/2019JE006005
Abstract: NASA's strategy in exploring Mars has been to follow the water, because water is essential for life, and it has been found that there are many locations where there was once liquid water on the surface. Now perhaps, to narrow down the search for life on a barren basalt‐dominated surface, there needs to be a refocusing to a strategy of “follow the nutrients.” Here we model the entry of metallic micrometeoroids through the Martian atmosphere, and investigate variations in micrometeorite abundance at an analogue site on the Nullarbor Plain in Australia, to determine where the common limiting nutrients available in these (e.g., P, S, Fe) become concentrated on the surface of Mars. We find that dense micrometeorites are abundant in a range of desert environments, becoming concentrated by aeolian processes into specific sites that would be easily investigated by a robotic rover. Our modeling suggests that micrometeorites are currently far more abundant on the surface of Mars than on Earth, and given the far greater abundance of water and warmer conditions on Earth and thus much more active weather system, this was likely true throughout the history of Mars. Because micrometeorites contain a variety of redox sensitive minerals including FeNi alloys, sulfide and phosphide minerals, and organic compounds, the sites where these become concentrated are far more nutrient rich, and thus more compatible with chemolithotrophic life than most of the Martian surface.
Publisher: Wiley
Date: 07-06-2014
DOI: 10.1111/SED.12124
Abstract: This study formulates a comprehensive depositional model for hydromagnesite–magnesite playas. Mineralogical, isotopic and hydrogeochemical data are coupled with electron microscopy and field observations of the hydromagnesite–magnesite playas near Atlin, British Columbia, Canada. Four surface environments are recognized: wetlands, grasslands, localized mounds (metre‐scale) and amalgamated mounds composed primarily of hydromagnesite [Mg 5 ( CO 3 ) 4 ( OH ) 2 ·4H 2 O], which are interpreted to represent stages in playa genesis. Water chemistry, precipitation kinetics and depositional environment are primary controls on sediment mineralogy. At depth (average ≈ 2 m), Ca–Mg‐carbonate sediments overlay early Holocene glaciolacustrine sediments indicating deposition within a lake post‐deglaciation. This mineralogical change corresponds to a shift from siliciclastic to chemical carbonate deposition as the supply of fresh surface water (for ex le, glacier meltwater) ceased and was replaced by alkaline groundwater. Weathering of ultramafic bedrock in the region produces Mg– HCO 3 groundwater that concentrates by evaporation upon discharging into closed basins, occupied by the playas. An uppermost unit of Mg‐carbonate sediments (hydromagnesite mounds) overlies the Ca–Mg‐carbonate sediments. This second mineralogical shift corresponds to a change in the depositional environment from subaqueous to subaerial, occurring once sediments ‘emerged’ from the water surface. Capillary action and evaporation draw Mg– HCO 3 water up towards the ground surface, precipitating Mg‐carbonate minerals. Evaporation at the water table causes precipitation of lansfordite [Mg CO 3 ·5H 2 O] which partially cements pre‐existing sediments forming a hardpan. As carbonate deposition continues, the weight of the overlying sediments causes compaction and minor lateral movement of the mounds leading to amalgamation of localized mounds. Radiocarbon dating of buried vegetation at the Ca–Mg‐carbonate boundary indicates that there has been ca 8000 years of continuous Mg‐carbonate deposition at a rate of 0·4 mm yr −1 . The depositional model accounts for the many sedimentological, mineralogical and geochemical processes that occur in the four surface environments elucidating past and present carbonate deposition.
Publisher: Informa UK Limited
Date: 12-11-2017
Publisher: Elsevier BV
Date: 11-2012
Publisher: Elsevier BV
Date: 02-2010
Publisher: Springer Science and Business Media LLC
Date: 25-01-2021
DOI: 10.1038/S41467-020-20627-W
Abstract: Melting of the Greenland Ice Sheet is a leading cause of land-ice mass loss and cryosphere-attributed sea level rise. Blooms of pigmented glacier ice algae lower ice albedo and accelerate surface melting in the ice sheet’s southwest sector. Although glacier ice algae cause up to 13% of the surface melting in this region, the controls on bloom development remain poorly understood. Here we show a direct link between mineral phosphorus in surface ice and glacier ice algae biomass through the quantification of solid and fluid phase phosphorus reservoirs in surface habitats across the southwest ablation zone of the ice sheet. We demonstrate that nutrients from mineral dust likely drive glacier ice algal growth, and thereby identify mineral dust as a secondary control on ice sheet melting.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 07-2022
Publisher: Elsevier BV
Date: 06-2014
Publisher: Springer Science and Business Media LLC
Date: 05-12-2007
Abstract: This study provides experimental evidence for biologically induced precipitation of magnesium carbonates, specifically dypingite (Mg 5 (CO 3 ) 4 (OH) 2 ·5H 2 O), by cyanobacteria from an alkaline wetland near Atlin, British Columbia. This wetland is part of a larger hydromagnesite (Mg 5 (CO 3 ) 4 (OH) 2 ·4H 2 O) playa. Abiotic and biotic processes for magnesium carbonate precipitation in this environment are compared. Field observations show that evaporation of wetland water produces carbonate films of nesquehonite (MgCO 3 ·3H 2 O) on the water surface and crusts on exposed surfaces. In contrast, benthic microbial mats possessing filamentous cyanobacteria ( Lyngbya sp.) contain platy dypingite (Mg 5 (CO 3 ) 4 (OH) 2 ·5H 2 O) and aragonite. Bulk carbonates in the benthic mats (δ 13 C avg. = 6.7‰, δ 18 O avg. = 17.2‰) were isotopically distinguishable from abiotically formed nesquehonite (δ 13 C avg. = 9.3‰, δ 18 O avg. = 24.9‰). Field and laboratory experiments, which emulated natural conditions, were conducted to provide insight into the processes for magnesium carbonate precipitation in this environment. Field microcosm experiments included an abiotic control and two microbial systems, one containing ambient wetland water and one amended with nutrients to simulate eutrophic conditions. The abiotic control developed an extensive crust of nesquehonite on its bottom surface during which [Mg 2+ ] decreased by 16.7% relative to the starting concentration. In the microbial systems, precipitation occurred within the mats and was not simply due to the capturing of mineral grains settling out of the water column. Magnesium concentrations decreased by 22.2% and 38.7% in the microbial systems, respectively. Laboratory experiments using natural waters from the Atlin site produced rosettes and flakey globular aggregates of dypingite precipitated in association with filamentous cyanobacteria dominated biofilms cultured from the site, whereas the abiotic control again precipitated nesquehonite. Microbial mats in the Atlin wetland create ideal conditions for biologically induced precipitation of dypingite and have presumably played a significant role in the development of this natural Mg-carbonate playa. This biogeochemical process represents an important link between the biosphere and the inorganic carbon pool.
Publisher: Elsevier BV
Date: 04-2017
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 08-2022
Publisher: Elsevier BV
Date: 04-2018
Publisher: American Chemical Society (ACS)
Date: 11-2018
Publisher: Society of Economic Geologists
Date: 06-2021
DOI: 10.5382/ECONGEO.4803
Abstract: Mineral distributions can be determined in drill core s les from a Carlin-type gold deposit, using micro-X-ray fluorescence (µXRF) raster data. Micro-XRF data were collected using a Bruker Tornado µXRF scanner on split drill core s les (~25 × 8 cm) with data collected at a spatial resolution of ~100 µm. Bruker AMICS software was used to identify mineral species from µXRF raster data, which revealed that many in idual s le spots were mineral mixtures due to the fine-grained nature of the s les. In order to estimate the mineral abundances in each pixel, we used a linear programming (LP) approach on quantified µXRF data. Quantification of µXRF spectra was completed using a fundamental parameters (FP) standardless approach. Results of the FP method compared to standardized wavelength dispersive spectrometry (WDS)-XRF of the same s les showed that the FP method for quantification of µXRF spectra was precise (R2 values of 0.98–0.97) although the FP method gave a slight overestimate of Fe and K and an underestimate of Mg abundance. Accuracy of the quantified µXRF chemistry results was further improved by using the WDS-XRF data as a calibration correction before calculating mineralogy using LP. The LP mineral abundance predictions were compared to Rietveld refinement results using X-ray diffraction (XRD) patterns collected from powders of the same drill core s les. The root mean square error (RMSE) for LP-predicted mineralogy compared to quantitative XRD results ranges from 0.91 to 7.15% for quartz, potassium feldspar, pyrite, kaolinite, calcite, dolomite, and illite. The approaches outlined here demonstrates that µXRF maps can be used to determine mineralogy, mineral abundances, and mineralogical textures not visible with the naked eye from fine-grained sedimentary rocks associated with Carlin-type Au deposits. This approach is transferable to any ore deposit, but particularly useful in sedimentary-hosted ore deposits where ore and gangue minerals are often fine grained and difficult to distinguish in hand specimen.
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 12-2016
Publisher: Wiley
Date: 24-03-2022
DOI: 10.1111/SED.12991
Abstract: The Coorong Lakes, South Australia, are one of the models for unravelling the ‘Dolomite Problem’. Critically, today only a few modern environments remain where large quantities of very high magnesium calcite (VHMC Ca 0.5 Mg 0.5 CO 3 also described as protodolomite or disordered dolomite) and magnesite (MgCO 3 ) precipitate. Previously conducted laboratory studies demonstrate that carbonate minerals can precipitate via classical and non‐classical crystallization pathways. This study uses the preserved crystal sizes, morphologies and microstructures of Ca–Mg carbonates in the Coorong Lakes (Milne Lake, Pellet Lake and North Stromatolite Lake) to evaluate which crystallization pathway most likely occurred. In the fine‐grained sediments of these lakes, very high magnesium calcite and magnesite occur as aggregate particles of nanocrystals ( nm). Rietveld refinements using X‐ray diffraction data give modelled L vol –IB crystallite size values of nm for all carbonates. Transmission electron microscopy shows that, within VHMC and magnesite particles, nanocrystals have an almost identical orientation of their crystal lattice fringes. This is morphologically similar to Ca–Mg carbonates formed via an amorphous carbonate precursor in non‐classical crystallization laboratory experiments. Precipitation of carbonate minerals via an amorphous‐to‐crystalline pathway requires the water to be supersaturated relative to both crystalline and amorphous phases. In the Coorong Lakes, surface water likely only becomes supersaturated relative to amorphous carbonate phases in the late summer after extensive evaporation. Observations suggest that VHMC and dolomite do not directly precipitate from bulk modern seawater, despite oversaturation relative to the crystalline phases, because seawater is undersaturated with respect to amorphous calcium magnesium carbonate, thus limiting the precipitation through a non‐classical crystallization pathway.
Publisher: Springer Science and Business Media LLC
Date: 11-05-2016
DOI: 10.1038/NATURE17678
Abstract: It is widely accepted that Earth's early atmosphere contained less than 0.001 per cent of the present-day atmospheric oxygen (O2) level, until the Great Oxidation Event resulted in a major rise in O2 concentration about 2.4 billion years ago. There are multiple lines of evidence for low O2 concentrations on early Earth, but all previous observations relate to the composition of the lower atmosphere in the Archaean era to date no method has been developed to s le the Archaean upper atmosphere. We have extracted fossil micrometeorites from limestone sedimentary rock that had accumulated slowly 2.7 billion years ago before being preserved in Australia's Pilbara region. We propose that these micrometeorites formed when sand-sized particles entered Earth's atmosphere and melted at altitudes of about 75 to 90 kilometres (given an atmospheric density similar to that of today). Here we show that the FeNi metal in the resulting cosmic spherules was oxidized while molten, and quench-crystallized to form spheres of interlocking dendritic crystals primarily of magnetite (Fe3O4), with wüstite (FeO)+metal preserved in a few particles. Our model of atmospheric micrometeorite oxidation suggests that Archaean upper-atmosphere oxygen concentrations may have been close to those of the present-day Earth, and that the ratio of oxygen to carbon monoxide was sufficiently high to prevent noticeable inhibition of oxidation by carbon monoxide. The anomalous sulfur isotope (Δ(33)S) signature of pyrite (FeS2) in seafloor sediments from this period, which requires an anoxic surface environment, implies that there may have been minimal mixing between the upper and lower atmosphere during the Archaean.
Publisher: Thomas Telford Ltd.
Date: 11-2014
Abstract: This study investigates the effect of pyrite contents on the strength behaviour of lime-slag-treated acid sulfate soils (ASS). A fixed lime content of 10% and slag contents of 0 to 25% were investigated. This study finds that unconfined compressive strength USC development of treated ASS at slag contents less than 10% was below or at the level of treated non-pyritic soils at comparable curing periods. Moreover, the effect of pyrite variations on the UCS behaviour was negligible at these low slag contents. A slag content exceeding 10% increases the strength of treated ASS considerably over the 365 day curing periods investigated. However, a drop of strength after 180 days of curing was recorded for a slag content of 25%. Mineralogical study indicated a probable development of deleterious reaction product (i.e. thaumasite), which is deemed to be responsible for the degradation of strength.
Publisher: European Association of Geochemistry
Date: 04-2017
Publisher: Elsevier BV
Date: 09-2021
Publisher: MDPI AG
Date: 02-05-2014
DOI: 10.3390/MIN4020399
Publisher: Mineralogical Society of America
Date: 08-2006
DOI: 10.2138/AM.2006.2058
Publisher: American Chemical Society (ACS)
Date: 31-12-2016
Abstract: A microbially accelerated process for the precipitation of carbonate minerals was implemented in a s le of serpentinite mine tailings collected from the abandoned Woodsreef Asbestos Mine in New South Wales, Australia as a strategy to sequester atmospheric CO2 while also stabilizing the tailings. Tailings were leached using sulfuric acid in reaction columns and subsequently inoculated with an alkalinity-generating cyanobacteria-dominated microbial consortium that was enriched from pit waters at the Woodsreef Mine. Leaching conditions that dissolved 14% of the magnesium from the serpentinite tailings while maintaining circumneutral pH (1800 ppm, pH 6.3) were employed in the experiment. The mineralogy, water chemistry, and microbial colonization of the columns were characterized following the experiment. Micro-X-ray diffraction was used to identify carbonate precipitates as dypingite [Mg5(CO3)4(OH)2·5H2O] and hydromagnesite [Mg5(CO3)4(OH)2·4H2O] with minor nesquehonite (MgCO3·3H2O). Scanning electron microscopy revealed that carbonate mineral precipitates form directly on the filamentous cyanobacteria. These findings demonstrate the ability of these organisms to generate localized supersaturating microenvironments of high concentrations of adsorbed magnesium and photosynthetically generated carbonate ions while also acting as nucleation sites for carbonate precipitation. This study is the first step toward implementing in situ carbon sequestration in serpentinite mine tailings via microbial carbonate precipitation reactions.
Publisher: Informa UK Limited
Date: 26-11-2017
Publisher: Mineralogical Society of America
Date: 2013
Publisher: Society of Economic Geologists
Date: 03-2020
DOI: 10.5382/ECONGEO.4710
Abstract: Accelerated carbonation of ultramafic mine tailings has the potential to offset CO2 emissions produced by mining ores from Cu-Ni-platinum group element, podiform chromite, diamondiferous kimberlite, and historical chrysotile deposits. Treatments such as acid leaching, reaction of tailings with elevated concentrations of gaseous CO2, and optimization of tailings pore water saturation have been shown to enhance CO2 sequestration rates in laboratory settings. The next challenge is to deploy treatment technologies on the pilot and field scale while minimizing cost, energy input, and adverse environmental impacts. Implementation of accelerated tailings carbonation at field scale will ideally make use of in situ treatments or modified ore-processing routes that employ conventional technology and expertise and operate at close to ambient temperatures and pressures. Here, we describe column experiments designed to trial two geochemical treatments that address these criteria: (1) direct reaction of partially saturated ultramafic tailings with synthetic flue gas from power generation (10% CO2 in N2) and (2) repeated heap leaching of ultramafic tailings with dilute sulfuric acid. In the first experiment, we report rapid carbonation of brucite [Mg(OH)2] in the presence of 10% CO2 gas within tailings s led from the Woodsreef chrysotile mine, New South Wales, Australia. Within four weeks, we observe a doubling of the amount of CO2 stored within minerals relative to what is achieved after three decades of passive mineral carbonation via air capture in the field. Our simulated heap leaching experiments, treated daily with 0.08 M H2SO4, produce high-Mg leachates that have the potential to sequester 21.2 kg CO2 m–2 y–1, which is approximately one to two orders of magnitude higher than the rate of passive carbonation of the Woodsreef mine tailings. Although some nesquehonite (MgCO3 · 3H2O) forms from these leachates, most of the Mg is precipitated as Mg sulfate minerals instead. Therefore, an acid other than H2SO4 could be used otherwise, sulfate removal would be required to maximize CO2 sequestration potential from acid heap leaching treatments. Reactive transport modeling (MIN3P) is employed to simulate acid leaching experiments and predict the effects of heap leaching for up to five years. Finally, our synchrotron X-ray fluorescence microscopy results for leached tailings material reveal that valuable trace metals (Fe, Ni, Mn, Co, Cr) become highly concentrated within secondary Fe (hydr)oxide minerals at the pH neutralization horizon within our column experiments. This discrete horizon migrates downward, and our reactive transport models indicate it will become increasingly enriched in first-row transition metals in response to continued acid leaching. Acid-leaching treatments for accelerated mineral carbonation could therefore be useful for ore processing and recovery of base metals from tailings, waste rock, or low-grade ores.
Publisher: Mineralogical Society
Date: 10-2010
DOI: 10.1180/MINMAG.2010.074.5.903
Abstract: The sodium-magnesium hydrated double salt konyaite, Na 2 Mg(SO 4 ) 2 ·5H 2 O, has been studied by single-crystal X-ray diffraction and thermogravimetry on synthetic s les and by quantitative X-ray diffraction utilizing the Rietveld method on natural s les from the Mount Keith mine, Western Australia. Konyaite crystallizes in space group P 2 1 / c , with the cell parameters: a = 5.7594(10), b = 23.914(4), c = 8.0250(13) Å, β = 95.288(9)°, V = 1100.6(3) Å 3 and Z = 4. The crystal structure has been refined to R 1 = 3.41% for 2155 reflections [F o σ(F o )] and 6.44% for all 3061 reflections, with all atoms located. Quantitative phase analysis utilizing the Rietveld method was undertaken on five s les of konyaite-bearing mine tailings from the Mount Keith Nickel Mine, Western Australia. Konyaite was found to decompose over time and after 22 months had transformed to other sulphate and amorphous phases. Blödite did not increase in any ofthe s les indicating that konyaite may not always transform to blödite. Over the same time frame, synthetic konyaite completely decomposed to a mixture of thenardite (Na 2 SO 4 ), hexahydrite (MgSO 4 · 6H 2 O), blödite (Na 2 Mg(SO 4 ) 2 ·4H 2 O) and löweite (Na 12 Mg 7 (SO 4 ) 13 ). Detection of konyaite and other Mg-rich sulphates is important in terms of CO 2 fixation. Magnesium bound to sulphate mineral phases reduces the overall potential of tailings piles to lock up atmospheric carbon in Mg carbonates, such as hydromagnesite. Amorphous sulphates are also highly reactive and may contribute to acid mine drainage ifpresent in large quantities, and may dissolve carbonate phases which have already sequestered carbon.
Publisher: American Chemical Society (ACS)
Date: 17-11-2010
DOI: 10.1021/ES1021125
Abstract: Dypingite, a hydrated Mg-carbonate mineral, was precipitated from high-pH, high salinity solutions to investigate controls on carbon fixation and to identify the isotopic characteristics of mineral sequestration in mine tailings. δ(13)C values of dissolved inorganic carbon content and synthetic dypingite are significantly more negative than those predicted for equilibrium exchange of CO(2) gas between the atmosphere and solution. The measured δ(13)C of aqueous carbonate species is consistent with a kinetic fractionation that results from a slow diffusion of atmospheric CO(2) into solution. During dypingite precipitation, dissolved inorganic carbon concentrations decrease and δ(13)C values become more negative, indicating that the rate of CO(2) uptake into solution was outpaced by the rate of carbon fixation within the precipitate. This implies that CO(2) gas uptake is rate-limiting to CO(2) fixation. δ(13)C of carbonate mineral precipitates in mine tailings and of DIC in mine process waters display similar (13)C-depletions that are inconsistent with equilibrium fractionation. Thus, the rate of carbon fixation in mine tailings may also be limited by supply of CO(2). Carbon sequestration could be accelerated by increasing the partial pressure of CO(2) in tailings ponds or by using chemicals that enhance the uptake of gaseous CO(2) into aqueous solution.
Publisher: Cambridge University Press (CUP)
Date: 2013
DOI: 10.1666/12-074R.1
Abstract: Rangea is the type genus of the Rangeomorpha, an extinct clade near the base of the evolutionary tree of large, complex organisms which prospered during the late Neoproterozoic. It represents an iconic Ediacaran taxon, but the relatively few specimens previously known significantly hindered an accurate reconstruction. Discovery of more than 100 specimens of Rangea in two gutter casts recovered from Farm Aar in southern Namibia significantly expands this data set, and the well preserved internal and external features on these specimens permit new interpretations of Rangea morphology and lifestyle. Internal structures of Rangea consist of a hexaradial axial bulb that passes into an axial stalk extending the length of the fossil. The axial bulb is typically filled with sediment, which becomes increasingly loosely packed and porous distally, with the end of the stalk typically preserved as an empty, cylindrical cone. This length of the axial structure forms the structural foundation for six vanes arranged radially around the axis, with each vane consisting of a bilaminar sheet composed of a repetitive pattern of elements exhibiting at least three orders of self-similar branching. Rangea was probably an epibenthic frond that rested upright on the sea bottom, and all known fossil specimens were transported prior to their final burial in storm deposits.
Publisher: American Chemical Society (ACS)
Date: 31-08-2011
DOI: 10.1021/ES201648G
Abstract: Ultramafic mine tailings from the Diavik Diamond Mine, Canada and the Mount Keith Nickel Mine, Western Australia are valuable feedstocks for sequestering CO₂ via mineral carbonation. In microcosm experiments, tailings were leached using various dilute acids to produce subsaline solutions at circumneutral pH that were inoculated with a phototrophic consortium that is able to induce carbonate precipitation. Geochemical modeling of the experimental solutions indicates that up to 2.5% and 16.7% of the annual emissions for Diavik and Mount Keith mines, respectively, could be sequestered as carbonate minerals and phototrophic biomass. CO₂ sequestration rates are mainly limited by cation availability and the uptake of CO₂. Abundant carbonate mineral precipitation occurred when heterotrophic oxidation of acetate acted as an alternative pathway for CO₂ delivery. These experiments highlight the importance of heterotrophy in producing sufficient DIC concentrations while phototrophy causes alkalinization of waters and produces biomass (fatty acids = 7.6 wt.%), a potential feedstock for biofuel production. Tailings storage facilities could be redesigned to promote CO₂ sequestration by directing leachate waters from tailings piles into specially designed ponds where carbonate precipitation would be mediated by both chemical and biological processes, thereby storing carbon in stable carbonate minerals and potentially valuable biomass.
Publisher: Frontiers Media SA
Date: 30-06-2017
Publisher: Wiley
Date: 14-01-2011
DOI: 10.1111/J.1472-4669.2010.00265.X
Abstract: Microbialites were discovered in an open pit pond at an abandoned asbestos mine near Clinton Creek, Yukon, Canada. These microbialites are extremely young and presumably began forming soon after the mine closed in 1978. Detailed characterization of the periphyton and microbialites using light and scanning electron microscopy was coupled with mineralogical and isotopic analyses to investigate the mechanisms by which these microbialites formed. The microbialites are columnar in form (cm scale), have an internal spherulitic fabric (mm scale), and are mostly made of aragonite, which is supersaturated in the subsaline pond water. Initial precipitation is seen as acicular aragonite crystals nucleating onto microbial biomass and detrital particles. Continued precipitation entombs benthic diatoms (e.g. Brachysira vitrea ), filamentous algae (e.g. Oedogonium sp.), dinoflagellates, and cyanobacteria. The presence of phototrophs at spherulite centers strongly suggests that these microbes play an important initial role in aragonite precipitation. Substantial growth of in idual spherulites occurs abiotically through periodic precipitation of aragonite that forms concentric laminations around spherulite centers while pauses in spherulite growth allow for colonization by microbes. Aragonite associated with biomass (δ 13 C = −4.6‰ VPDB) showed a 13 C‐enrichment of 0.8‰ relative to aragonite exhibiting no biomass (δ 13 C = −5.4‰ VPDB), which suggests a modest removal of isotopically light dissolved inorganic carbon by phototrophs. The combination of a low sedimentation rate, high calcification rate, and low microbial growth rate appears to result in the formation of these microbialites. The formation of microbialites at an historic mine site demonstrates that an anthropogenically constructed environment can foster microbial carbonate formation.
Publisher: American Chemical Society (ACS)
Date: 22-06-2021
Publisher: Elsevier BV
Date: 2019
Publisher: Mary Ann Liebert Inc
Date: 03-2020
Abstract: The advent of microfluidics has revolutionized the way we understand how microorganisms propagate through microporous spaces. Here, we apply this understanding to the study of how endolithic environmental microorganisms colonize the interiors of sterile rock. The substrates used for our study are stony meteorites from the Nullarbor Plain, Australia a semiarid limestone karst that provides an ideal setting for preserving meteorites. Periodic flooding of the Nullarbor provides a mechanism by which microorganisms and exogenous nutrients may infiltrate meteorites. Our laboratory experiments show that environmental microorganisms reach depths greater than 400 μm by propagating through existing brecciation, passing through cracks no wider than the diameter of a resident cell (
Publisher: Mineralogical Society of America
Date: 10-2018
DOI: 10.2138/AM-2018-6515
Publisher: Proceedings of the National Academy of Sciences
Date: 14-09-2022
Start Date: 2015
End Date: 12-2017
Amount: $358,536.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2013
End Date: 12-2014
Amount: $350,000.00
Funder: Australian Research Council
View Funded Activity