Total Sulfur Research Articles

Quantifying SO2 oxidation pathways to atmospheric sulfate using stable sulfur and oxygen isotopes: laboratory simulation and field observation

Abstract. The formation of secondary sulfate in the atmosphere remains controversial, and it is an urgent need to seek a new method to quantify different sulfate formation pathways. Thus, SO2 and PM2.5 samples were collected from 4 to 22 December 2019 in the Nanjing region. Sulfur and oxygen isotopic compositions were synchronously measured to study the contribution of SO2 homogeneous and heterogeneous oxidation to sulfate. Meanwhile, the correlation of δ18O values between H2O and sulfate from SO2 oxidation by H2O2 and Fe3+ / O2 was simulatively investigated in the laboratory. Based on isotope mass equilibrium equations, the ratios of different SO2 oxidation pathways were quantified. The results showed that secondary sulfate constituted higher than 80 % of total sulfate in PM2.5 during the sampling period. Laboratory simulation experiments indicated that the δ18O value of sulfate was linearly dependent on the δ18O value of water, and the slopes of linear curves for SO2 oxidation by H2O2 and Fe3+ / O2 were 0.43 and 0.65, respectively. The secondary sulfate in PM2.5 was mainly ascribed to SO2 homogeneous oxidation by OH radicals and heterogeneous oxidation by H2O2 and Fe3+ / O2. SO2 heterogeneous oxidation was generally dominant during sulfate formation, and SO2 oxidation by H2O2 predominated in SO2 heterogeneous oxidation reactions, with an average ratio around 54.6 %. This study provided an insight into precisely evaluating sulfate formation by combining stable sulfur and oxygen isotopes.

Use of water quality parameters to assess the ecological health of Atlantic coastal areas in the northwestern Morocco

Coastal waters are confronted with multiple stressors, including chemical contamination/pollution and climate change. Water quality along the Atlantic coast of Morocco was assessed, in this study, at six stations over four seasons, including three heavily industrialized stations (S2, S4, and S6) and three clean stations (S1, S3, and S5), spreading over a distance of ∼300 km from Azemmour to Essaouira cities. The physicochemical characteristics (temperature, salinity, pH, dissolved oxygen, suspended matter, and sulfate), and chlorophyll-a, as well as nutrients (nitrite, nitrate, ammonium, total phosphorus, orthophosphate, and silicate) were analyzed to investigate their spatial and seasonal trends in the study areas. The results revealed significant spatiotemporal variations in the distribution of the hydrological characteristics across the sampling sites. In addition, the observed sulfate and nutrient concentrations showed significant spatial and seasonal differences. The disturbed stations showed the highest concentrations of nutrients, while the clean stations exhibited the highest concentrations of chlorophyll-a, particularly in the spring season. As expected, the compressive pollution index (CPI) and water pollution index (WPi) results supported the pollution status of stations. Accordingly, the surface seawater quality was better in the clean stations compared to the polluted stations. According to the CPI and WPi values, the sampling stations were classified in the following descending order of pollution, from strongly and moderately polluted stations to slightly or unpolluted stations (S4 > S2 > S6 > S1> S3 > S5). The total phosphorus, orthophosphate, sulfate, and chlorophyll-a concentrations were substantially higher than the surface water quality standards of Morocco, especially at the most industrialized stations in the winter.The physicochemical, biological, and nutrient data obtained in this study provide a valuable reference for assessing the ecological quality status of the Atlantic coastal environments in the study areas.

Ecotoxic effect in Allium cepa due to sphalerite weathering arising in calcareous conditions.

The ecotoxic effect of Zn species arising from the weathering of the marmatite-like sphalerite ((Fe, Zn)S) in Allium cepa systems was herein evaluated in calcareous soils and connected with its sulfide oxidation mechanism to determine the chemical speciation responsible of this outcome. Mineralogical analyses (X-ray diffraction patterns, Raman spectroscopy, scanning electron microscopy and atomic force microscopy), chemical study of leachates (total Fe, Zn, Cd, oxidation-reduction potential, pH, sulfates and total alkalinity) and electrochemical assessments (chronoamperometry, chronopotentiometry, cyclic voltammetry, and electrochemical impedance spectroscopy) were carried out using (Fe, Zn)S samples to elucidate interfacial mechanisms simulating calcareous soil conditions. Results indicate the formation of polysulfides (Sn2-), elemental sulfur (S0), siderite (FeCO3)-like, hematite (Fe2O3)-like with sorbed CO32- species, gunningite (ZnSO4·H2O)-like phase and smithsonite (ZnCO3)-like compounds in altered surface under calcareous conditions. However, the generation of gunningite (ZnSO4·H2O)-like phase was predominant bulk-solution system. Quantification of damage rates ranges from 75 to 90% of bulb cells under non-carbonated conditions after 15-30days, while 50-75% of damage level is determined under neutral-alkaline carbonated conditions. Damage ratios are 70.08 and 30.26 at the highest level, respectively. These findings revealed lower ecotoxic damage due to ZnCO3-like precipitation, indicating the effect of carbonates on Zn compounds during vegetable up-taking (exposure). Other environmental suggestions of the (Fe, Zn)S weathering and ecotoxic effects under calcareous soil conditions are discussed.

Geochemistry and petrology of Early Permian lacustrine shales in the Lodève Basin, Southern France: Depositional history, organic matter accumulation and thermal maturity

The lacustrine shales in the Lodève Basin, southern France, serve as excellent archives of paleo-lake development as well as climatic evolution during the Early Permian. In this study, an extensive dataset is presented encompassing organic petrographic data, major and trace element quantification, bulk and molecular organic geochemical proxies, as well as compound-specific stable carbon isotope data derived from the analysis of 36 black shale outcrop samples originating from the Usclas-St. Privat Formation (USPF), Tuilières-Loiras Formation (TLF), and Viala Formation (VF). All sample are thermally oil-mature, as evident from a vitrinite reflectance (VRr) of around 0.8%. The lower section of the USPF, characterized by notably higher total sulfur (TS) concentrations, displays total organic carbon (TOC) and TS contents spanning from 2.69 to 7.83 (avg. 4.28) wt% and 0.42–1.55 (avg. 1.09) wt%, respectively. In contrast, the upper section of the USPF (average TOC of 2.59 wt%), TLF (average TOC of 2.66 wt%), and VF (average TOC of 3.17 wt%) exhibit considerably lower TS contents of 0.26 wt%, 0.22 wt%, and 0.17 wt%, respectively. The lower section of the USPF, characterized by the lowest pristane/phytane (Pr/Ph) ratio and the highest TS/TOC ratios and chemical index of alteration (CIA) values, was deposited in oxygen-depleted and saline lacustrine environments. These conditions prevailed under more humid climatic conditions and were probably related to marine incursions. In contrast, the upper section of the USPF, the TLF, and the VF display elevated Pr/Ph ratios but reduced TS/TOC and CIA values, signifying deposition within oxic-dysoxic and freshwater-brackish bottom water conditions with a significant change towards arid conditions. All samples are characterized by low vitrinite and inertinite contents together with consistently similar average values of Al2O3 and TiO2. The biomarker analysis suggests that the organic matter (OM) in most samples mainly originates from planktonic/algal biomass with additional microbial OM. Only the lower section of the USPF displays a slightly enhanced contribution of terrestrial OM input and also more detrital elements. It is concluded that the structural evolution of the basin from narrow deep towards wider and shallower settings as well as the postulated marine transgressive events during early stages played a crucial role in shaping the deposition environments of the two distinct sets of lacustrine shales, thereby influencing the OM accumulation mechanisms. In contrast, the substantial climatic aridification seems to have a relatively minor impact on the sources of OM and the conditions prevailing within the water column.

Translocation of tropical peat surface to deeper soil horizons under compaction controls carbon emissions in the absence of groundwater

Compaction is recognized as an effective method for mitigating the risk of fires by enhancing soil moisture levels. This technique involves restricting peat pore spaces through compaction, facilitating improved capillary action for water retention and rehydration. The compaction of tropical peatlands, while beneficial for fire prevention, has the potential to influence biogeochemical processes and subsequent carbon emissions. The magnitude of compaction and groundwater level are strongly coupled in such environments, making it difficult to distinguish the control of physicochemical properties. Therefore, this study seeks to understand how peat compaction affects its properties, carbon emissions, and their relationship, with a focus on geophysical processes. Intact peat samples were collected from a secondary peat swamp forest and an oil palm plantation in Selangor, Peninsular Malaysia. Compaction treatments were applied to achieve three levels of volume reduction. CO2 and CH4 emissions were measured using an automated gas analyzer, and the physicochemical properties of the peat were determined. The results revealed that mechanical compaction significantly altered the physicochemical properties of the secondary forest peat, displaying an opposite pattern to the oil palm plantation, particularly regarding total nitrogen and sulfur. Moreover, the average reduction percentage ratio of CO2 emissions (from 275.4 to 182.0 mg m-2 hr-1; 33.9%) to CH4 uptakes (from -17.8 to -5.2 µg m-2 hr-1; 70.1%) (~1:2) indicated distinct stages of decomposition and translocation of less decomposed peat to deeper layers due to compaction, predominantly in secondary peat swamp forest samples. The oil palm plantation samples were unaffected by compaction in terms of physicochemical properties and carbon emissions, indicating the ineffectiveness of this approach for reducing fire risk in already drained systems. This study underscores the necessity of understanding the effects of compaction in the absence of groundwater to accurately evaluate the widespread application of this technique.

Changes in Soil Chemistry and Microbial Communities in Rhizospheres of Planted Gastrodia elata on a Barren Slope and under a Forest

Continuous cropping of the important achlorophyllous medicinal orchid Gastrodia elata Blume causes an imbalance in soil microecology leading to soil-borne diseases. However, the impacts on different land covers remain largely unknown. Hence, this study aimed to investigate changes in the soil nutrient composition and the global microbial community structure in rhizospheres of G. elata cultivated on a barren slope (HPGJ) and under a forest (LXT) using integrated shotgun metagenomics and an analysis of soil chemical properties. High-throughput sequencing revealed an increase in the abundance of Proteobacteria, Actinobacteria, Mucoromycota, Basidiomycota, and Ascomycota, which drive N- and C-cycling genes in HPGJ and LXT. Notably, the fungal community was significantly improved in the HPGJ (from 0.17% to 23.61%) compared to the LXT (from 0.2% to 2.04%). Consequently, mineral cycling was enhanced in the HPGJ, resulting in a more improved soil nutrient composition than in the LXT. The soil chemical properties analysis unveiled a significant increase in the contents of the total nitrogen, NO3−-N, organic matter, total carbon, organic carbon, total sulfur, and total phosphorus in the HPGJ, while no changes were recorded in the LXT. It was noteworthy that the abundance of pathogenic microorganisms increased significantly in the HPGJ compared to the LXT. Our results provide supporting data to optimize G. elata cultivation on slopes.

Different Fractions of Sulphur, Their Correlations with Soil Properties and Yield of Soybean and Safflower Influenced by Long Term Fertilizers Experiment under Vertisol

Sulphur is an important element in Indian soils, and it has been found as a major limitation for increasing the oil seed productivity. The results emerged out from experimental field showed that 100% NPK + FYM @ 5 t ha-1 recorded significantly maximum fractions of sulphur, namely organic sulphur (37.13 mg kg-1), non-sulphate sulphur (118.28 mg kg-1), water soluble sulphur (12.28 mg kg-1), heat soluble sulphur (1.45 mg kg-1) and total sulphur (153.65 mg kg-1) followed by only application of organic manuring as FYM @ 10 t ha-1. Different sulphur fractions exhibited negative correlation with pH and EC while, found positive significant with organic carbon, available N, P, K and S. Similarly, soybean and safflower both crops produced higher yields of grain (18.30 and 8.66 q ha-1) and straw (28.70 and 27.73 q ha-1), respectively. However, higher N (131.80 kg ha-1), P (26.27 kg ha-1), K (56.44 kg ha-1), S (15.43 kg ha-1) and Zn (253.90 g ha-1 ) uptake were observed by soybean whereas, N (54.43 kg ha-1), P(16.47 kg ha-1), K( 69.90 kg ha-1), S ( 11.29 kg ha-1 ) and Zn (162.19 g ha-1) were observed by safflower in application of 100 % NPK + FYM @ 5 t ha-1.

Removal of total phosphate and sulfate from industrial wastewater by recirculating flow in nanofiltration

This study is related to industrial wastewater treatment in Indonesia using nanofiltration membrane technology and was carried out on a pilot scale. This research aims to study the total removal of phosphate and sulfate from industrial wastewater through flow recirculation in nanofiltration and the membrane pressure factors that influence the removal of these pollutants. The treated wastewater is industrial wastewater belonging to Jababeka Infrastruktur Corp. and is arranged in various concentrations. The membrane module in this study uses a spiral wound with model specifications NF2-4040 and a two-stage membrane system. The reactor used provides crossflow velocity and is processed by recirculation. The research results stated that variations in concentration and recovery rate provided total removal of phosphate and sulfate in the range of 70-90% and pressure reached 11 bar as both increased. This research has proven that nanofiltration membrane technology can remove total phosphate and sulfate, with the consequence that the more concentrated the wastewater being treated, the greater the pressure required.

Association and textural-compositional evolution of pyrite-organic matter in coals of the Tarakan, Barito, and Pasir Basins, Kalimantan, Indonesia

The Barito, Pasir, and Tarakan Basins in Kalimantan Island is the most extensive coal-bearing sedimentary basin in Indonesia, mined since 1989. The coal is notable in having high sulfur coal content, exceeding >10% in some cases, contributed by the presence of pyrite. The latter issue contributed to interest in the coal, forming economic mineral deposits hosted by the sedimentary pyrite and organic matter. Novel findings of this research providing valuable information of trace element behavior during the diagenetic conditions. This paper documents the textural and compositional evolution of pyrite-organic matter of coals using coal petrographic, proximate, ultimate, total sulfur content, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), electron probe micro analyser (EPMA), and Raman spectroscopy. Coals from Kalimantan are mainly characterized by medium-high sulfur content (>3%) and the maximum temperatures reached by organic matter during diagenesis are 166 ± 10 °C for the Pasir Basin, 136 ± 11 °C for the Barito Basin, and 132 ± 12 °C for the Tarakan Basin. Pyrite is mainly found as large size framboids (mostly >5 μm), indicating formation in the sedimentary layer with dysoxic bottom water conditions during early–late diagenetic stages. The framboidal pyrite was likely formed in detrovitrinite and gelovitrinite under topogenous mire conditions, due to the degradation of macerals and biochemical gelification, which provided the organic templates. High concentrations of trace elements (TE) of framboidal pyrite, such as 1) Cu, Ni, and Co in the Pasir Basin and 2) As in the Barito Basin, likely reflect the local sedimentary provenance and underlying basement rocks. Pyrite texture evolved with increasing diagenetic temperatures from 1) framboidal pyrite, 2) recrystallized framboidal pyrite rims, and 3) anhedral, anhedral-euhedral pyrite transition, and euhedral massive pyrite. This study shows a similar average TE concentrations of various pyrite texture, suggesting that the TEs are not remobilized during the evolution of pyrite at the diagenetic stages.

Nutrient content of vegetation and soil of four conifer species growing under different site and competing vegetation management conditions

In this study we examined the long-term effects of competing vegetation control on the total nutrient content of different ecosystem components of 19-year-old Douglas-fir (DF), western hemlock (WH), western redcedar (WRC), and grand fir (GF) stands growing in Oregon’s central Coast Range (CR) and of DF and WRC growing in Oregon’s Cascade mountain foothills (CF). Nutrient content responses were evaluated under two contrasting vegetation control treatments, including the Control (no herbicide application post-planting), and VM (5 consecutive years of herbicide application post-planting). Both treatments involved a pre-planting herbicide application. The ecosystem components were divided into overstory (planted crop trees), midstory, understory, forest floor, fine roots, and mineral soil. All samples were analyzed for content (mass per unit ground area) of total carbon, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, iron, manganese, sodium, and zinc. VM effects on total plant derived nutrient masses were more prominent than differences in concentrations. Ca was the only nutrient for which all species showed higher plant derived masses in the VM condition. Plant derived tissue content of C, Cu, P, and B all tended to be higher in VM plots, with the exception of WRC plots at the CR site. This case was an outlier due to the fact that Control plots developed significantly more biomass as a result of high midstory biomass, whereas the VM plots developed relatively little midstory and crop tree biomass. There were few differences in soil nutrients content between species and treatments, and those that were significant were unable to be explained by differences in uptake by plant species. Notably, total soil N of WRC at the CR site was significantly lower for VM plots. This may indicate the potential for VM applied to a slow growing species, such as WRC, to reduce ecosystem retention of N. With the exception of C and N, total soil nutrient reserves were orders of magnitude greater than total plant derived masses. This indicated that there is low probability of an adverse effect of VM on soil nutrient stores.

Release of Carbon Dioxide and Water-Soluble Carbon Amended with Rice and Wheat Residues in an Inceptisols of Varanasi

ABSTRACT Crop residues are the main organic source of nutrients in agricultural soils. The active pool of soil organic carbon plays a dominant role in crop production and soil health. Rice and wheat residues were used in 90 days incubation study under controlled conditions (25°C temperature and maximum water-holding capacity) to estimate the release of carbon dioxide and water-soluble carbon in an Indo-Gangetic alluvial soil (Inceptisols) of Varanasi. The experiment was laid out in a factorial completely randomized design with three replications. The rice and wheat residues showed a wide variation in the content of their total carbon (TC), total nitrogen (TN), total phosphorus (TP) and total sulfur (TS). Out of the two crop residues added to the soil, rice residue had higher carbon dioxide-carbon (CO2-C) release than that of the wheat residue over control. Results revealed that conjunctive application of rice residue along with urea (20 kg N ha−1) and Trichoderma viride (10 kg ha−1) had resulted in a higher content of CO2-C (7.44 mg per 100 g per day) at 90 days of the incubation period. The amount of CO2 (mg) released, increases with a combination of crop residues with urea (20 kg N ha−1) and Trichoderma viride (10 kg ha−1) up to 90 days over control. The highest release of CO2 (204.70 mg) was recorded with rice residue treated with urea (20 kg N ha−1) and Trichoderma viride (10 kg ha−1). The study also revealed that the release of water-soluble carbon decreases with an increase in the incubation period irrespective of treatment. At 90 days of the incubation period, the control without any crop residue addition has the highest water-soluble carbon content (459.75 µg/g). The present study indicates that the incorporation of rice and wheat residues along with urea and supplemental decomposers (Trichoderma viride) has the potential to release adequately active organic carbon pool parameters such as CO2 and water-soluble carbon in an Inceptisols of Varanasi region of India.

Inhibition of high sulfur on functional microorganisms and genes in slightly contaminated soil by cadmium and chromium

It is generally accepted that sulfur can passivate the bioavailability of heavy metals in soil, but it is not clear whether high sulfur in cadmium (Cd) and chromium (Cr) contaminated soil has negative effect on soil microbial community and ecological function. In this study, total sulfur (TS) inhibited the Chao 1, Shannon, Phylogenetic diversity (Pd) of bacterial and Pd of fungi in slightly contaminated soil by Cd and Cr around pyrite. TS, total potassium, pH, total chromium, total cadmium, total nitrogen, soil organic matter were the predominant factors for soil microbial community; the contribution of TS in shaping bacterial and fungal communities ranked at first and fifth, respectively. Compared with the low sulfur group, the abundance of sulfur sensitive microorganisms Gemmatimonas, Pseudolabrys, MND1, and Schizothecium were decreased by 68.79–97.22% (p < 0.01) at high sulfur one; the carbon fixation, nitrogen cycling, phosphorus cycling and resistance genes abundance were significantly lower (p < 0.01) at the latter. Such variations were strongly and closely correlated to the suppression of energy metabolism (M00009, M00011, M00086) and carbon fixation (M00173, M00376) functional module genes abundance in the high sulfur group. Collectively, high sulfur significantly suppressed the abundances of functional microorganisms and functional genes in slightly contaminated soil with Cd and Cr, possibly through inhibition of energy metabolism and carbon fixation of functional microorganisms. This study provided new insights into the environmental behavior of sulfur in slightly contaminated soil with Cd and Cr.

Desulfurisasi Batubara Dengan Metode Leaching Menggunakan Naoh Dan HCL Di PT. Anugerah Krida Utama, Kutai Kartanegara, Kalimantan Timur

The utilization of coal as a fossil fuel causes several ecological problems, as for the consequences of the coal combustion process, namely pollution and emissions. Combustion of high sulfur coal produces sulfur dioxide gas (SO2). This sulfur dioxide (SO2) will become H2SO4 (sulfuric acid) which can directly or indirectly disrupt human life, such as causing acid rain, causing tightness in the respiratory tract and causing corrosion and shortening the life of factory equipment. To reduce SO2 gas, a reduction in sulfur content is carried out before combustion which is called desulfurization. This research was conducted using the leaching method with variations in leaching agent and solution concentration. Leaching agents used in this study are NaOH and HCl. The coal to be desulfurized is coal from PT Anugerah Krida Utama with an initial total sulfur content of 4,05% adb. 10 grams of coal with a size of 0,212 mm was leached with 250 ml of chemical solution using a hot plate stirrer at 80˚C and 250 rpm for 1 hour. The results showed that the optimum condition for leaching agent NaOH occurred at a concentration of 8 M showing the initial total sulfur content of 4,05% adb decreased to 1,69% adb with a maximum percentage decrease of 58,27% and at leaching agent HCl the optimum condition occurred at a concentration of 1 M showing the initial total sulfur content of 4,05% adb decreased to 2,91% adb with a maximum percentage decrease of 28,14%.

Development of a three-stage process for high coal desulfurization and char yield

Efficient pyrolytic desulfurization with high char yield is a promising yet challenging approach for the cleaner utilization of abundant high-sulfur coal reserves. In this study, we have discovered that a single pyrolysis process under either oxidizing or reducing conditions cannot efficiently remove various sulfur forms while preserving a high char yield. To address this challenge, we propose a three-stage desulfurization process: a low-temperature oxidative pyrolysis (LTOP), a high-temperature reductive pyrolysis (HTRP), and a dry magnetic separation process. LTOP operates in a fluidized bed for only a few minutes to oxidize the diamagnetic pyrite particle surface to Fe2O3 while minimizing char losses. HTRP occurs in another fluidized bed for an appropriate duration to substantially remove organic sulfur while reducing Fe2O3 to highly magnetic Fe3O4 or Fe. Partially magnetized pyrite particles are then removed from the char through magnetic separation. When applied to anthracite coal with a total sulfur content of 4.99%, this process achieves nearly 100% desulfurization for pyritic sulfur and 74.81% for organic sulfur. Ultimately, it recovers 94.5% of the original coal excluding volatiles as char, with 91.6% being low-sulfur char.

Comparative Soil Analysis from Different Crime Prone Areas of Kottayam and Kollam Districts of Kerala for Forensic Characterization

Soil is the loose surface material that covers land on which plants grow. It consists of a mixture of organic remains, clay, and rock particles, which gives it its uniqueness from place to place. Because of the uniqueness of soil, it has a high evidential value in the field of forensic science. In the present study, research has been conducted to check the range of variations in the soil collected from different crime-prone areas of Kottayam and Kollam districts of Kerala by physical, chemical, microscopic, and instrumental examination. In physical examination, soil colour, texture, consistency, and density were measured, and in chemical examination, pH and total soluble sulphate of the soil were measured. In instrumental examination, Heavy metal analysis was done by using Atomic Absorption Spectrometry (AAS), which helps to measure the amount of trace elements present in the soil. The study found that each soil has some significant variations that make it unique. In the field of forensic science, this can be highly helpful in determining the origin of soil by examining its colour, texture, structure, content, etc.

Geodetector analysis of individual and joint impacts of natural and human factors on maternal and child health at the provincial scale

This ecological study examined the individual and joint impacts of natural–human factors on the spatial patterns of maternal and child health status in China at the provincial scale in 2020. We considered natural factors (forest coverage, average temperature, and total sulfur dioxide and particulate matter emissions) and human factors (economic development, urbanization, healthcare access, and education level). We combined maternal, infant, and under-five mortality rates into a composite maternal and child health index using the entropy method. The spatial autocorrelation analysis of this index highlighted distinct health patterns across provinces, whereas the geodetector method assessed the effects of natural–human factors on the patterns. A notable east–central–west stepwise decline in health status was observed. Global Moran’s I showed positive spatial clustering, with high–high clustering areas in the Yangtze River Delta and low–low clustering areas in western regions. Factor detection identified eight significant natural–human factors impacting maternal and child health, with total sulfur dioxide emission density having the greatest impact. The interaction between average schooling years and total sulfur dioxide emission notably affected maternal and child health patterns. The study concludes that natural–human factors critically affect the spatial distribution of maternal and child health.

Mineralogy and Geochemistry of High-Sulfur Coals from the M8 Coal Seam, Shihao Mine, Songzao Coalfield, Chongqing, Southwestern China

Mineral matter, including minerals and non-mineral elements, in coal is of great significance for geological evolution, high-value coal utilization, and environment protection. The minerals and elemental geochemistry of Late Permian coals from the M8 coal seam, Shihao mine, Songzao coalfield in Chongqing, were analyzed to evaluate the sediment source, sedimentary environment, hydrothermal fluids, and utilization prospects of critical metals. The average total sulfur (4.21%) was high in coals, which mainly exists in the forms of pyritic sulfur. Kaolinite, pyrite, calcite, quartz, illite and illite/smectite (I/S) mixed layers, and anatase predominated in coals, with trace amounts of chlorite, ankerite, and siderite. Epigenetic cell- and fracture-filling pyrite, veined calcite, and ankerite were related to hydrothermal fluids and/or pore water after the diagenesis stage. Compared to the world’s hard coals, As and Cd are enriched in the Shihao M8 coals, and Li, Cr, Co, Zr, Mo, Pb, and Tb are slightly enriched. These high contents of sulfophile elements may be related to seawater intrusion. The terrigenous clastics of the Shihao M8 coals originated from the felsic–intermediate rocks atop the Emeishan Large Igneous Provinces (ELIP) (Kangdian Upland), while the roof and floor samples were derived from Emeishan high-Ti basalt. Through the combination of sulfur contents and indicator parameters of Fe2O3 + CaO + MgO/SiO2 + Al2O3, Sr/Ba and Y/Ho, the depositional environment of peat swamp was found to be influenced by seawater. Although the critical elements in coal or coal ash did not reach the cut-off grade for beneficial recovery, the concentration of Li and Zr were high enough in coal ash.

Coal middling retreatment using high voltage pulses technique: selective liberation mechanism

ABSTRACT With combined efforts from the mineral liberation analyzer (MLA), elementary analysis and sulfur speciation analysis, this study expands upon coal fragmentation using high voltage pulse (HVP) by incorporating an understanding about deportment of specific minerals due to density behavior. Mineral characteristics showed that the minerlisation of middlings sample was predominantly banded, and pyrite was most of all associated with the mineral matter, to a lesser extent, with the organic matter. In addition, it was found that the pyritic sulfur attained a higher propensity for the heavy densities than the total sulfur, and the results were supported by speciation analysis. For Test 3, the total sulfur (0.86%) predominantly arose from organic sulfur due to the condensation of organic matter in the −1.3RD fraction, whereby the pyritic sulfur merely accounted for 25.80% of the total sulfur. It is concluded that the metalliferous grain-induced breakdown resulted in pulse selectivity between the middling particles. The improvement in coal middlings reprocessability (deashing and desulfuration) predominantly arose from the generation of cracks/microcracks. The results of this study have shown that the high voltage pulse (HVP) technique holds considerable promise for coal middlings reprocessing in comparison with the mechanical crushing method.

Photocatalytic desulfurization of gas condensate using zinc diacetate and cadmium diacetate liquid catalysts

This inquiry studied the application of photocatalytic desulfurization as an effective method for removing sulfur-containing organic compounds from gas condensate extracted from oil wells. To this end, cadmium diacetate and zinc diacetate compounds were prepared as the liquid catalysts. Then their structures were confirmed and their properties were determined by common methods, including FTIR, NMR, and UV. Subsequently, their performances as catalysts were investigated by an optical technique for the desulfurization process. Accordingly, the study used a photoreactor equipped with a 250 W mercury ultraviolet lamp with a maximum wavelength of 365 nm, and investigated and optimized the effect of the ratios of the influencing parameters on the total sulfur removal efficiency. These included the ratios of fuel to photocatalyst, H2O2, and acetonitrile. Ratios of 1:2:3:2 and 1:3:2:1 (fuel: catalyst: oxidant: solvent) of zinc and cadmium diacetate led to 93.5 % and 87.1 % reduction of the total sulfur content, respectively, after 60 min since the exposure process. Also, under sunlight, the total sulfur removal was 67.0 % for the Zn diacetate and 42.0 % for Cd diacetate. Liquid diacetate photocatalysts were successfully recycled over five cycles with only a maximum of 10 % reduction in efficiency. The kinetics of the systems studied were evaluated under optimal conditions and it was found that both systems fit the pseudo-first order model with rate constants of 0.148 min−1 and 0.098 min−1, respectively. In the final step, some physicochemical properties of the desulfurized sample crucial in evaluation of fuel quality were determined under optimal conditions and compared with the properties of the original sample. The results indicated that the liquid photocatalysts used in the experiment increased the quality of the fuel by changing its important indicators by reducing its freezing point in addition to increasing its cetane number.

Isotope ratios of total C, N, and S in particulate matter simultaneously calibrated by mixed USGS and IAEA reference materials

This study presents a method for calibrating the isotope ratios of the total carbon, nitrogen, and sulfur in particulate matter (PM) collected from the Seoul metro using an elemental analyzer-isotope ratio mass spectrometer (EA-IRMS). Mixtures of isotope reference materials (MRMs) from the U.S. Geological Survey (USGS) and International Atomic Energy Agency (IAEA) reference materials formed an input dataset for generalized least squares (GLS) regression to yield calibration lines. The analytical method proposed in this study enabled the measurement of stable isotope ratios of total carbon, nitrogen, and sulfur simultaneously. Results showed good linearity and repeatability for carbon and nitrogen isotopes, but poor results for sulfur isotopes due to peak broadening. Reference values with uncertainties for the isotope ratios of total carbon, nitrogen, and sulfur were determined for the collected PM, demonstrating twice as much uncertainty as that of the USGS and IAEA reference materials. Homogeneity was the biggest uncertainty source for the calibrated values.