Black Rock Research Articles

Geochemical Characterization of Organic Rich Black Rocks of the Niutitang Formation to Reconstruct the Paleoenvironmental Settings during Early Cambrian Period from Xiangxi Area, Western Hunan, China

Geochemical Characterization of Organic Rich Black Rocks of the Niutitang Formation to Reconstruct the Paleoenvironmental Settings during Early Cambrian Period from Xiangxi Area, Western Hunan, China

Peperites

Peperites are volcanosedimentary materials generated by the mingling of magma and unconsolidated wet sediments. They have unique insights into submarine volcanisms and the tectonic environments where they form. For the 1st time, the authors identified two types of peperites (blocky and fluidal) hosted by micritic limestone rocks in the Walash Volcanosedimentary Group of the Mawat area, Kurdistan Region-Iraq. They are designated as peperitic facies one and two (PF1 and PF2) and consist of black basaltic rocks mixed with chocolate-brown micritic limestone rocks. Their abundance demonstrates the contemporaneity of deep marine sediment deposition and submarine volcanism during Walash’s nascent arc. Despite hydrothermal alteration, the basaltic rocks retained their magmatic textures. Basaltic rocks comprise mainly albite, anorthite, diopside, hematite, and alkali-feldspar. Calcite dominates micritic limestone rocks, while quartz is minor. Based on geochemical data, igneous sections are basaltic rocks with tholeiitic series that are strongly enriched in Light Rare Earth Elements with low concentration ratios of (La/Yb) and (Sr/Y), indicating geochemical affinity to normal island arc basalt with a primitive arc signature. Furthermore, their formation is thought to be caused by partial melting of subducted slabs deep within 30 km and the associated derived fluids above the subducted slab. Thirteen species of planktonic foraminifera (Morozovella) are identified through paleontological research and biostratigraphy. Using these various tools lead the authors to illustrate the tectonic setting of the formation of peperitic rocks in arc fronts of the subducted Walash arc during the Middle to Late Paleocene (60 Ma).

Black adzes in the Early Neolithic of Belgium: Contribution of the Raman microspectrometry and petrography in characterization and sourcing

Early Neolithic (Linear Pottery Culture) adzes originate from settlements and workshops accompany the neolithization of Belgium. They are made from a wide range of extraregional lithic raw materials such as metamorphic green rocks (amphibolite) and black volcanic rocks (“basalt’) beside more local or regional raw material as flints, light-coloured (sedimentary and lightly metamorphic) quartzites, black lydites (Cambrian nodular phtanite of Céroux-Mousty and Lower Namurian banded phtanites) and dark grey Lower Namurian silicified sandstones previously called “Micaceous sandstones of Horion-Hozémont’. The discovery of the workshop of Noirfontaine near the city of Liège in the 1970s and 1980s provides exceptional assemblage available for updating analytical studies. This research focuses on the multi-scale characterization, the discrimination and sourcing both Cambrian and Namurian black sedimentary rocks rich in secondary silica composing Early Neolithic adzes found in Belgium. Their black colour results from finely dispersed organic matter, but the absence of palynomorphs does not allow a biostratigraphic ascription. Additional petrographical analyses (Optical Petrography, Scanning Electron Microscope), X-ray diffraction, chemical analyses (Energy Dispersive Spectroscopy) and measuring the degree of graphitization of the organic matter through Raman microspectrometry have been decisive in identifying the geological and geographical provenances by comparing the acquired results with geological reference samples collected in the field or through reference collections. Cambrian lydites are coming from a very restricted area and were preferred to other more local rock sources.

Spatial distribution of the critical mineral resource element titanium in China and its influencing factors

In China, titanium is found in multi-metal symbiotic ore deposits that present sorting difficulties, low recovery rates, high production costs, and low overall resource utilization rates. The concentration and distribution of titanium in the pedosphere must be better understood to assess the potential titanium resources. The China Geochemical Baseline project obtained harmonized soil and rock geochemical data covering mainland China and provided reliable data for 76 elements (including titanium) from 3382 top (0–25 cm) and 3380 deep (>100 cm) sediment or alluvial soil samples and 12,201 rock samples. In this study, titanium concentrations were determined by X-ray fluorescence spectrometry under strict quality control. The median titanium concentration values in the top and deep samples, which were considered geochemical baseline values, were 3498 mg/kg and 3406 mg/kg, respectively, with mean values of 3661 mg/kg and 3585 mg/kg, respectively. The titanium concentrations ranged from 266 to 24,674 mg/kg and 324 to 25,504 mg/kg in the top and deep soil samples, respectively. The 75 % range (Q25–Q95) of titanium concentrations in the rock ranged from 978 to 8299 mg/kg. The median titanium concentration was 2555 mg/kg in the rock samples, while the mean concentration was 3089 mg/kg. The geochemical map of titanium indicated that low titanium concentrations below Q25 (<3498 and 3406 mg/kg in the top and deep samples, respectively) are primarily distributed in southern Xinjiang, Tibet, Qinghai, Gansu, and Inner Mongolia. The distribution of low titanium content in the soils is likely attributed to these regions being covered by deserts (e.g., Gobi) and glaciers. Soils with high titanium concentrations are widely distributed in the Emeishan large igneous province at the southwest margin of the Yangzi block, which is related to the large distribution of intermediate-basic rock in the area, as well as along the northeast-southwest direction of the Yangtze block, which extends for nearly 1600 km. Moreover, these soils are mainly associated with the black rock system and intermediate-basic dikes. Soil titanium concentrations are affected by various factors, including the occurrence of tectonic activity and distribution of the black rock system, intermediate-basic rock (especially basalt), and VTi magnetite deposits. In particular, the large igneous province area generated by a mantle column represents the main location of VTi magnetite deposit formation and the area with the highest titanium content. In addition to providing detailed information about the titanium distribution in the pedosphere and rock of mainland China, the project can also provide basic geochemical data for the development and utilization of titanium resources and the formulation of critical mineral industry policies.

Exploring the Potential of Black Shale Source Rocks in the Babouri-Figuil Basin, Northern Cameroon: A Study on Organic Petrography

Exploring the Potential of Black Shale Source Rocks in the Babouri-Figuil Basin, Northern Cameroon: A Study on Organic Petrography

Paleomagnetism and age of the Leucite Hills Volcanic complex, Wyoming: Implications for eruptive history, landscape evolution, and the geomagnetic instability timescale (GITS)

The Leucite Hills Volcanic Field, southwest Wyoming comprises two dozen volcanic features including necks, flows, dikes, and plugs. It has been the focus of many petrologic studies as its volcanic and shallow intrusive rocks are one of the only surficial manifestations of ultrapotassic lamproite. We build on paleomagnetic findings of Sheriff and Shive (1980) by providing further paleomagnetic data from the Boars Tusk dike and Black Rock flows. We also characterize the magnetic mineral assemblage of these lamproites. Principal component analysis of alternating field (AF) and thermal demagnetization data indicate that the dike and breccias of Boars Tusk record a reversed magnetic polarity and the Black Rock lava records a normal polarity, both consistent with previous findings. This recording is typically carried by minerals with coercivities >15 mT and susceptibility measurements indicate magnetite, maghemite, and titanomagnetite as likely magnetic carriers. AF and thermal demagnetization experiments evince secondary magnetizations held by lower coercivity grains, likely caused by lightning strikes. 40Ar/39Ar incremental heating experiments from Boars Tusk and Black Rock give plateau ages of ∼2500 ka and ∼900 ka, respectively. Recent advances in the chronology of geomagnetic field reversals and excursions during the Quaternary permit integration of the Boars Tusk dike into the lower Matuyama chron, whereas the Black Rock lavas most probably record the Kamikatsura excursion. Notably, Black Rock records high inclinations that suggest the short-lived excursion achieved a full geomagnetic reversal, something not observed at other localities recording the Kamikatsura excursion. The Leucite Hills offer further opportunities to refine the Quaternary geomagnetic instability time scale (GITS), and to improve understanding of the eruptive and geomorphic evolution of this unusual volcanism.

Comparative genomics reveals environmental adaptability and antimicrobial activity of a novel Streptomyces isolated from soil under black Gobi rocks.

A novel Streptomyces strain, designated 3_2T, was isolated from soil under the black Gobi rock sample of Northwest China. The taxonomic position of this strain was revealed by a polyphasic approach. Comparative analysis of the 16S rRNA gene sequences indicated that 3_2T was closely related to the members of the genus Streptomyces, with the highest similarity to Streptomyces rimosus subsp. rimosus CGMCC 4.1438 (99.17%), Streptomyces sioyaensis DSM 40032 (98.97%). Strain 3_2T can grow in media up to 13% NaCl. The genomic DNA G + C content of strain 3_2T was 69.9%. We obtained the genomes of 22 Streptomyces strains similar to strain 3_2T, compared the average nucleotide similarity, dDDH and average amino acid identity, and found that the genomic similarity of the new isolate 3_2T to all strains was below the threshold for interspecies classification. Chemotaxonomic data revealed that strain 3_2T possessed MK-9 (H6) and MK-9 (H8) as the major menaquinones. The cell wall contained LL-diaminopimelic acid (LL-DAP) and the whole-cell sugars were ribose and glucose. The major fatty acid methyl esters were iso-C16:0 (23.6%) and anteiso-C15:0 (10.4%). The fermentation products of strain 3_2T were inhibitory to Staphylococcus aureus and Bacillus thuringiensi. The genome of 3_2T was further predicted using anti-smash and the strain was found to encode the production of 41 secondary metabolites, and these gene clusters may be key to the good inhibitory activity exhibited by the strain. Genomic analysis revealed that strain 3_2T can encode genes that produce a variety of genes in response to environmental stresses, including cold shock, detoxification, heat shock, osmotic stress, oxidative stress, and these genes may play a key role in the harsh environment in which the strain can survive. Therefore, this strain represents a novel Streptomyces species, for which the name Streptomyces halobius sp. nov. is proposed. The type strain is 3_2T (= JCM 34935T = GDMCC 4.217T).

Low-cost materials for swine wastewater treatment using adsorption and Fenton's process.

Untreated swine wastewater (SW) discharge leads to serious consequences such as water quality decreasing related to eutrophication and proliferation of harmful algae containing cyanotoxins, which can cause acute intoxication in humans. The use of untreated pig farming effluent as fertilizer can lead to the accumulation of polluting compounds. Biological treatments can degrade organic matter but have the disadvantage of requiring large areas and high retention times and demonstrating low efficiencies in the degradation of refractory compounds such as pharmaceutical compounds. In this ambit, the performance of four low-cost materials was evaluated for treatment of a swine wastewater using physical-chemical processes such as adsorption and Fenton's process. The tested materials are two natural resources, red volcanic rock from Canary (RVR) Islands and black volcanic rock (BVR) from Azores, and two industry residues, red mud (RM) and iron filings (IF). Among the tested materials, only IFs are catalytically active for Fenton's peroxidation. Still, RVR, BVR, and RM were efficient adsorbents removing up to 67% of COD. The combination between adsorption followed by Fenton's process using IF as catalyst showed interesting results. When RM is applied as adsorbent in the diluted effluent, it was able to remove 67% and 90% of COD for adsorption and adsorption followed by IF Fenton, respectively. At those conditions, the resultant treated effluent accomplishes the requirements for direct discharge in the natural water courses as well as the parameters for water reusing.

Plume effects on Martian surface: Revealing evolution characteristics of plume-surface interaction at Tianwen-1 landing site

Engine plumes can seriously erode the Martian surface during the landing phase, causing a substantial alteration of the terrain of the immediate touchdown area and beyond. Furthermore, large amounts of lifted dust can block the view of boulders or craters, posing a serious threat to the lander's safety. Improving our understanding of the plume-surface interaction can reduce the risk of failure on a Mars landing mission. In situ studies on this subject are limited, particularly those relating to high-thrust single-nozzle engines. The Tianwen-1 represents the only Mars landing mission that employed such an engine with a thrust of ∼3000 N during the landing phase: Its success represents a unique opportunity in addressing this issue, providing an important reference for future Mars return missions. Here, we report the evolution characteristics of the plume-induced regolith erosion and the plume impingement effect measurements at the Tianwen-1 landing site. The results show that depressions and infilling are a complex process accompanying the changing of patterns as the lander descends. Specifically, the plume will seriously erode the area beneath the nozzle, causing the formation of a deep crater. Meanwhile, the expanding radial flow tends to flatten the peripheral area of the lander, which depends on the homogeneity of the regolith. To better quantify the impingement effects, some crucial parameters were extracted. The measured volume, diameter, and depth of the crater are 0.115 ± 0.019 m3, 1.50 m, and ∼0.35 m, respectively. We also calculated the total erosion area and volume as 4879.4 ± 297.7 m2 and 376.9 ± 102.2 m3. In addition, plume-induced infilling/erosion depths and rates during the landing phase were measured. Further, we investigated the shallow stratigraphic architecture exposed by the plume-induced crater beneath the lander, showing that it represents probably dust/sand-coated black rocks above at least ~35 cm thick, bright reddish materials. These results provide valuable insights into the plume impingement effects on the Martian surface and the shallow subsurface layer at the Tianwen-1 landing site, which will benefit future Mars explorations.

DETERMINATION OF THE TRACE ELEMENT COMPOSITION OF BLACK SHALE ROCKS AND ORES. CERTIFIED REFERENCE MATERIALS OF SLg-1 AND SChS-1

A set of methods for studying the trace element composition of black shales has been developed, including various options for preparing samples for analysis to determine individual groups of elements, including PGE and gold, by atomic spectroscopy methods (ICP-AES, ICP-MS, ETAAS). Data on the content of 54 elements in certified reference materials (CRMs) of black shale rocks SLg-1 and SChS-1 were obtained. The metrologically characterized data will make it possible to use these CRMs for a detailed study of the composition of rocks and ores containing carbonaceous matter. The relevance of the problem is due to the absence of natural multi-element CRMs, in which elevated and clarke contents of gold, silver, as well as all PGEs, are simultaneously certified.

The Archaeology of Burning Man: The Rise and Fall of Black Rock City by Carolyn L. White (review)

The Archaeology of Burning Man: The Rise and Fall of Black Rock City by Carolyn L. White (review)

Heavy Metal Regularity of Carboniferous Weathered Black Shale in Qiziqiao Area, Central Hunan

The Hunan region is a high geological background area of black rock series rich in various metallic elements; accordingly, local heavy metal pollution is severe. Previous studies on black shale have primarily focused on the lower Cambrian strata, while research on Carboniferous black shale remains scarce. To better explore the activity law of heavy metals during Carboniferous black shale weathering, this study analyzed the elemental components of samples through field observations of outcrops in the Qiziqiao area of central Hunan province, China using inductively coupled plasma mass spectrometry and X-ray fluorescence spectrometry. The results showed that the heavy metal content of black shale under different degrees of weathering varied greatly, with different heavy metals maintaining distinct migration and enrichment rules throughout this process. The heavy metal content in Carboniferous black shale and soils of central Hunan was generally less than that of the regional lower Cambrian black shale and soil; however, the Cd content in the black shale soil was slightly higher than background values, while the Sr content was substantially higher than background values. Heavy metals V, Cr, Co, Ni, Cu, and Pb were not generally leached or released during weathering, and may undergo relative enrichment or secondary enrichment. Comparatively, Zn, Cd, and Ba can be more readily leached and released, and may undergo secondary enrichment. The lithophilic element Sr tended to leach out overall and expressed strong activity, whereas the chemical activities of the high-field-strength elements, Zr and Hf, were relatively stable. During soil formation, all heavy metal elements save Sr were significantly enriched. The enrichment factor analysis of different degrees of weathered black shale reveals that the heavy metals Ba, Hf, and Sr in black shale soil originate from the parent rock. V, Cr, Co, Ni, Cu, Zn, Cd, and Pb are influenced by both natural and anthropogenic factors, with Cd being significantly impacted by human activities. The evaluation of soil heavy metals using the geoaccumulation index method indicates that V, Cr, Co, Ni, Cu, Zn, Zr, Ba, Hf, and Pb are non-polluted, Cd exhibits moderate pollution, and Sr shows moderately heavy pollution. From a geochemical perspective, it can be inferred that heavy metals in black shale soil are likely to be secondarily enriched in clay and iron oxide minerals.

Quantifying the Degree of Binder Availability in Recycled Asphalt Mix Design Using White and Black Rock Mixes

Quantifying recycled asphalt binder availability in recycled asphalt pavement (RAP) mix design is very essential, as the widely adopted 100% RAP binder availability assumption in RAP mix design never holds correct. Depending on the mix production condition, recycled binder stiffness, and virgin binder properties, the degree of binder availability in the mix is always partial. The present study proposes a simple procedure to estimate the degree of recycled binder availability in RAP mix design. In the proposed methodology, the designer needs to compare optimum binder content of bituminous mixes prepared using white rock aggregate gradation and virgin aggregates, along with mixes designed by blending black rock gradation and virgin aggregates blended in proportion to achieve the target white rock gradation. The binder content in the RAP fraction used in the blending exercise was determined using ignition oven method. RAP mix designs were performed for RAP material collected from two different sources, and design was performed for three mixing durations in a laboratory pug mill—60, 120, and 180s. The mixes were prepared with 50% RAP incorporation level. RAP material was conditioned at 110°C for 2 h, whereas virgin aggregates were superheated to 175°C. Using the methodology proposed, RAP binder availability was found to vary between 92.5% and 96.6% for softer RAP material, 75.9% to 91.5% for mixes incorporating stiffer RAP. With increasing mixing time, even though the total active binder content did not change significantly, a mixture performance test quantified the implication of increased RAP binder availability in mixes. A higher degree of binder activation resulted in mixes being rut resistant, while the same mixes exhibited relatively higher cracking susceptibility.

Comprehensive Quality Assessment of Soil-Maize Heavy Metals in High Geological Background Area

The aim of this study was to analyze the pollution degree and causes of soil and agricultural products in high geological background areas and to provide a basis for the safe production of agricultural products and the risk control of soil heavy metals. A total of 36 sets of soil-corn collaborative samples were collected in the farming area of Baolong Town, Wushan County, Chongqing City; the contents of heavy metals (Cd, Hg, Pb, As, and Cr) and soil pH in the soil-maize were analyzed, the pollution degree of heavy metals in the soil-maize was evaluated using the Nemerow comprehensive pollution index method (PN) and comprehensive quality impact index (IICQ). The sources of heavy metals in the soil and the influencing factors of heavy metal excess in corn were also analyzed. The results showed that the average value of soil heavy metal content in the study area was higher than the national and Chongqing soil background values, and the soil heavy metal enrichment effect was obvious. Cd was the main factor of soil-maize exceeding the standard, and the overall exceeding rates of soil and corn Cd were 91.67% and 30.55%, respectively. The evaluation results of the Nemerow comprehensive pollution index showed that the soil was dominated by heavy pollution, accounting for 63.89%. The soil-maize comprehensive quality impact index was dominated by moderate and severe pollution, accounting for 44.44% and 47.22%, respectively. From the perspective of the spatial distribution of heavy metal pollution, corn and soil pollution areas were inconsistent. Soil heavy metal pollution was mainly affected by the Permian and Triassic strata and was related to the secondary enrichment of black rock series and limestone areas. The Cd content of maize was mainly affected by soil pH, and maize was relatively safe under alkaline conditions. It is suggested that the soil in the study area should be divided into risk zones according to the stratum distribution, and the planting structure should be adjusted in the high-risk areas. For the low- and medium-risk areas, it is recommended to strengthen the monitoring of agricultural inputs and reduce the input of heavy metals in the soil. Additionally, we recommend carrying out agronomic regulation in acidic soil areas to improve soil acidification, plant corn varieties with low accumulation of heavy metals, and reduce the risk of agricultural products exceeding the standard.

Exploration of price variation, elemental profile, and fortification of commercial Indian edible salts with iodine, potassium, iron, magnesium, and calcium

The different types of edible rock salts (black, and pink) are fetching premium price compared to white sea salt. Survey of 300 individuals indicated that black rock salt is mainly used for sprinkling and sea salt for cooking. Further, people are switching to white rock salt for cooking due to the influence of traditional knowledge, friends, advertisements, and label claims. The elemental profile of commercial salt samples were analyzed to identify a scientific basis for this. We collected 14 different colored (black, pink) edible salt samples from supermarkets, local shops and health food shops in Mohali, Punjab, India. Various analytical and biochemical investigations were used for the analysis of 25 elements, vitamin and phenolic content. The recommended level of iodine (I) fortification (≥50% RDA) was found only in 20% of the salts studied. The potassium (K) fortification (10-20 % K/Na) was found only in two salts. One salt sample crossed the toxic limits of lead (Pb). Black salt exhibited the highest iron (Fe) (10-20% RDA). Other claimed nutrients/mineral Ca, Mg, vitamin and phenolic content was not observed in any salt (< 5 % RDA).In conclusion, taste, tradition, and social media affect salt preference, and our research provides the scientific data.

The Effect of Incorporating 100% of Undiluted and Diluted Reclaimed Epoxy Asphalt Materials into Pervious Cement Mixes

In order to improve the sustainability of road pavements, transportation agencies should consider designing pavements with recycled materials such as reclaimed epoxy asphalt pavement. Epoxy asphalt has recently attracted significant attention from the pavement community as a superior-performing binder that can help achieve long-lasting pavements. The recyclability of a proven long-life pavement material, such as epoxy asphalt, has now become one concern in promoting the use of epoxy asphalt binder in road pavements. Due to its thermosetting nature, the usual process of reclaiming asphalt pavement cannot be performed on epoxy asphalt pavement. Recent studies have investigated utilizing reclaimed epoxy asphalt materials in asphalt mixtures as black rock. In light of this, examining the use of reclaimed epoxy materials in cement-concrete mixes is important. The use of reclaimed epoxy asphalt materials in pavement construction is expected to gain more popularity and become a new sustainable construction option in various sustainable pavement applications in the near future. The main objective of this study is to investigate the effects of incorporating 100% reclaimed epoxy asphalt (hereinafter referred to as “epoxy RAP”) and reclaimed diluted epoxy asphalt materials (hereinafter referred to as “diluted epoxy RAP”) into cement-concrete mixes on the performance of the mixtures. The study also examined the effects of replacing cement with 5% silica fume on the performance of reclaimed mixtures. Five different mixtures were fabricated and tested in terms of density, void content, permeability, and compressive strength. Results of the density test revealed that replacing 100% natural aggregates with epoxy RAP and diluted epoxy RAP materials reduced density by an average of 10%. However, void content was found to increase with the incorporation of epoxy RAP, even when replacing Portland cement with silica fume. Regarding permeability, mixtures containing 100% epoxy RAP and diluted epoxy RAP materials have significantly higher permeability values compared with the natural mix value. However, adding 5% silica fume significantly reduced the permeability. Compressive test results indicated that substituting 100% of aggregates with epoxy RAP or diluted epoxy RAP materials would reduce compressive strength by 55% on average. Furthermore, adding silica fume to reclaimed mixes was found to have no apparent effect on compressive strength.

Impact of "black rock" on clinical outcomes after endovascular therapy for de novo calcified femoropopliteal lesions.

The relationship between severity of calcification and clinical outcomes after endovascular therapy (EVT) for femoropopliteal lesions is well known. We often encounter dense calcifications in our daily practice, which are darker than normal calcifications on angiography. Accordingly, we named it "black rock" (BR), and investigated its impact on clinical outcomes after EVT. We retrospectively analyzed 677 lesions in 495 patients who underwent EVT for de novo calcified femoropopliteal lesions at our hospital between April 2007 and June 2020. BR is defined as a calcification which is 1cm or more in length, occupies more than half of the vessel diameter, and appears darker than the body of the femur on angiography. Propensity score matching analysis was performed to compare clinical outcomes between lesions with BR [BR (+) group] and without BR [BR (-) group]. A total of 119 matched pairs of lesions were analyzed. Primary patency at 2years was significantly lower in the BR (+) group than in the BR (-) group (48% vs. 75%, p = .0007). Multivariate analysis revealed that the presence of BR [hazard ratio (HR) = 2.23, 95% confidence interval (CI); 1.48-3.38, p = .0001], lesion length (HR = 1.03, 95%CI; 1.00-1.06, p = .0244), and no scaffold use (HR = 1.58, 95%CI; 1.06-2.36, p = .0246) were predictors of restenosis. The presence of BR is independently associated with clinical outcomes after EVT for de novo calcified femoropopliteal lesions.

Characteristics and purification of Himalayan salt by high temperature melting

Abstract Himalayan rock salt contains a variety of minerals and trace elements, which is conducive to human health. The solutions of black rock salt and rose salt are alkaline, and the content of water insoluble matter is 0.34 and 0.083%, respectively. The element composition of water insoluble matter in rock salt is determined and analyzed. It is found that the main component of two kinds of rock salt water insoluble matter is soil. Due to the presence of water insoluble matter in rock salt, according to the different specific gravity of molten sodium chloride and insoluble matter, rock salt was purified by high-temperature melting method. Rose salt is mainly studied during purification. The results showed that the content of insoluble matter in rose salt decreased from 0.083 to 0.0024% after holding at 950°C for 40 min; the contents of arsenic, barium, and lead decreased to 0.0032, 0.61, and 0.21 mg·kg−1, respectively; the content of sodium increased to 39.24%, the contents of calcium, magnesium, and iron reached to 2,200, 855, and 1.31 mg·kg−1, respectively.

Lightweight SCC Development in a Low-Carbon Cementitious System for Structural Applications.

The utilization of manufactured lightweight aggregates adds another dimension to the cost of the preparation of self-compacting concrete (SCC). The common practice of adding absorption water to the lightweight aggregates before concreting leads to inaccurate calculations of the water-to-cement ratio. Moreover, the absorption of water weakens this interfacial bond between aggregates and the cementitious matrix. A particular type of black volcanic rock with a vesicular texture known as scoria rocks (SR) is utilized. With an adapted sequence of additions, the occurrence of water absorption can be minimized to overcome the issue of calculating the true water content. In this study, the approach of preparing the cementitious paste first with adjusted rheology followed by the addition of fine and coarse SR aggregates enabled us to circumvent the need for adding absorption water to the aggregates. This step has improved the overall strength due to the enhanced bond between the aggregate and the cementitious matrix, rendering a lightweight SCC mix with a target compressive strength of 40 MPa at 28 days, which makes it appropriate for structural applications. Different mixes were prepared and optimized for the best cementitious system that achieved the goal of this study. The optimized quaternary cementitious system included silica fume, class F fly ash, and limestone dust as essential ingredients for low-carbon footprint concrete. The rheological properties and parameters of the optimized mix were tested, evaluated, and compared to a control mix prepared using normal-weight aggregates. The results showed that the optimized quaternary mix satisfied both fresh and hardened properties. Slump flow, T50, J-ring flow, and average V-funnel flow time were in the ranges of 790-800 mm, 3.78-5.67 s, 750-780 mm, and 9.17 s, respectively. Moreover, the equilibrium density was in the range of 1770-1800 kg/m3. After 28 days an average compressive strength of 42.7 MPa, a corresponding flexural load of over 2000 N, and a modulus of rupture of 6.2 MPa were obtained. The conclusion is then drawn that altering the sequence of mixing ingredients becomes a mandatory process with scoria aggregates to obtain high-quality lightweight concrete for structural applications. This process leads to a significant improvement in the precise control of the fresh and hardened properties, which was unachievable with the normal practice used with lightweight concrete.

Environmental arsenic (As) and its potential relationship with endemic disease in southwestern China

Many cases of an unknown disease exhibiting the clinical features of limb gangrene, blisters, ulceration, and exfoliation have been reported in Daping village (DV) in southwestern China. However, the pathogenesis is unknown and has puzzled doctors for many years. A preliminary study on heavy metals and symptoms indicated that arsenic might pose the greatest threat to the health of local residents. Here, to explore the sources of and factors influencing arsenic enrichment in DV, whose residents exhibit signs of arsenic poisoning, the As contents in soil, water, and plants were systematically measured. The results indicated high As contents in plant and soil samples obtained from the area, and the source of As may be linked to the weathering of black shale rock. Ingestion of soil and consumption of plants were the two main As exposure pathways among children and adults, respectively, and children exhibited a higher health risk than adults. We presume and emphasize that when extreme drought events occur, humans might face unusual risks resulting from exposure to toxic elements and the direct consumption of highly polluted water. Our study provides a new perspective and sheds light on the environmental geochemistry and health links of this disease.