Mineral Dust Research Articles

Spontaneous convective pattern formation in a dusty plasma

We report on experimental observations of self-sustaining convective patterns in a dusty plasma system. The experiments are carried out in a capacitively coupled radio frequency (RF) argon plasma discharge in which a dusty plasma is produced by introducing micrometer-sized melamine formaldehyde particles. A self-sustained pair of convective cells with opposite vorticities is seen to appear in a lateral view of the system, beyond some threshold values of the background gas pressure and RF power. Particle tracking velocimetry measurements reveal the existence of a dust temperature gradient that is responsible for the convective counter-rotating patterns. The origin of the kinetic temperature gradient in the absence of any external heat source is attributed to the larger ion flux induced heating of the bottom layer of the dust cloud. The velocity and vorticity of the particles in the convective cell increase with an increase in the vertical kinetic temperature gradient. The experimental results compare reasonably well with the findings of molecular dynamics simulations of the laboratory system.

SPHERE RefPlanets: Search for ε Eridani b and warm dust

Context. Cold planets, including all habitable planets, produce only scattered light emission in the visual to near-infrared wavelength range. For this reason it is highly desirable to adapt the technique for the direct imaging of reflected light from extra-solar planets. Aims. For the nearby system ε Eri, we want to set much deeper detection limits for the expected scattered radiation from the radial velocity planet candidate (≈0.7 MJ) and the warm dust using the VLT/SPHERE adaptive optics (AO) instrument with the ZIMPOL imaging polarimeter. Methods. We carried out very deep imaging polarimetry of ε Eri based on 38.5 h of integration time with a broad-band filter (λc = 735 nm) for the search of the polarization signal from a planet or from circumstellar dust using AO, coronagraphy, high precision differential polarimetry, and angular differential imaging. The data were collected during 12 nights within four epochs distributed over 14 months and we searched for a signal in the individual epochs. We also combined the full data set to achieve an even higher contrast limit considering the Keplerian motion using the K-Stacker software. All data were also combined for the search of the scattering signal from extended dust clouds. We improved various data reduction and post-processing procedures and also developed new ones to enhance the sensitivity of SPHERE/ZIMPOL further. The final detection limits were quantified and we investigated the potential of SPHERE/ZIMPOL for deeper observations. Results. The data of ε Eridani provide unprecedented contrast limits but no significant detection of a point source or an extended signal from circumstellar dust. For each observing epoch, we achieved a 5 σ𝒩 point source contrast for the polarized intensity CP = Qϕ/I★ between 2 × 10−8 and 4 × 10−8 at a separation of ρ ≈ 1″, which is as expected for the proposed radial velocity planet at a quadrature phase. The polarimetric contrast limits are close to the photon noise limits for ρ > 0.6″ or about six times to 50 times better than the intensity limits because polarimetric imaging is much more efficient for speckle suppression. Combining the data for the search of a planet moving on a Keplerian orbit with the K-Stacker technique improves the contrast limits further by about a factor of two, when compared to an epoch, to about CP = 0.8 × 10−8 at ρ = 1″. This would allow the detection of a planet with a radius of about 2.5 RJ. Should future astrometry provide strong constraints on the position of the planet, then a 3 σ𝒩 detection at 1″ with CP ≈ 5 × 10−9 would be within reach of our data. The surface brightness contrast limits achieved for the polarized intensity from an extended scattering region is about 15 mag arcsec−2 at 1″ or up to 3 mag arcsec−2 deeper than previous limits. For ε Eri, these limits exclude the presence of a narrow dust ring and they constrain the dust properties. The photon statistics would allow deeper limits but we find a very weak systematic noise pattern probably introduced by polarimetric calibration errors. Conclusions. This ε Eri study shows that the polarimetric contrast limits for reflecting planets with SPHERE/ZIMPOL can be improved to a level below Cp < 10−8 by just collecting more data during many nights using software such as K-Stacker, which can combine all data considering the expected planet orbit. Contrast limits of Cp ≈ 10−9 are within reach for ε Eri if the search can be optimized for a planet with a well-known orbit. This limit is also attainable for other bright nearby stars, such as α Cen or Sirius A. Such data also provide unprecedented sensitivity for the search of extended polarized emission from warm circumstellar dust.

Geoecological monitoring during mining operations

In recent decades environmental quality assessment has become a fundamentally important task in the operation of mining enterprises. This assessment becomes an integral part of the strategy for determining maximum permissible loads for mining regions and is aimed at reducing geoecological risk in them. Technological processes of mining and processing plants generate emissions of various pollutants into the atmospheric air, lead to violation of adjacent territories. Monitoring, primarily of atmospheric air and soils, is necessary to ensure the ecological balance of such territories. Lebedinsky Mining and Processing Plant is one of the most significant sources of gas and dust emissions from massive explosions in quarries during ore extraction, which form a large dust and gas cloud, creating a risk of deterioration of the life of the population in the surrounding area. The article examines the main pollutants in soils and in the atmospheric air during mass explosions, and determines the areole of their distribution from the work site. The forecast of an increase in the concentrations of detected harmful substances for the next 50 years is given. A methodology for conducting geoecological monitoring during mining operations is proposed. The research results may be useful in assessing geoecological risks and developing measures to reduce them.

High resolution luminescence and radiocarbon dating of Holocene Aeolian silt (loess) in west Greenland

Loess–palaeosol sequences serve as valuable archives of changes in climate and atmospheric mineral dust deposition. However, little work has been conducted on Holocene loess in the Arctic, despite the sensitivity of this region to climate changes. Aeolian silt/loess profiles in the ice-free region of western Greenland near Kangerlussuaq were sampled to develop a robust age framework using both luminescence and bulk organic matter radiocarbon dating. Radiocarbon ages generally show consistent age increases with depth but are likely offset to younger ages due to sediment mixing in the upper 10–20 cm of the profiles. Quartz OSL signals exhibit insensitivity, while low-temperature infrared stimulated luminescence performed at 50 °C (IR50) and the post-IR IRSL at 180 °C (pIRIR180) signals of polymineral fine grain revealed a consistent natural inherited dose of approximately 5 Gy for pIRIR180 and an unbleachable residual of around 2 Gy for IR50, with substantial fading rates in the latter. This led to a notable age overestimation when compared with bulk organic matter radiocarbon ages. To develop an appropriate dating approach, we evaluated the differential bleaching rates of feldspar IR50 and pIRIR180 signals, and corrected for modern inherited doses. Radiocarbon ages measured on the bulk organic carbon oxidised at 400 °C (LT 14C) increased very consistently with depth, allowing calculation of accumulation rates. The presence of the atmospheric radiocarbon bomb signal at depth indicated down-mixing of surface material into the profile, which caused negative (younger) age offsets. The offset-corrected radiocarbon-based age-depth model could be compared to the luminescence results.We show that a combination of LT 14C with polymineral pIRIR180 dating allows the development of age models for these deposits. This multi-chronological approach reveals that loess accumulation in the region was initiated around 4 ka, probably consisting of two main phases of loess accumulation at 4–3 ka and <1 ka. The initial phase matches the proposed onset of aeolian sand activity in the wider region, but post-dates local ice retreat by c. 3 kyr. The more recent phase of accumulation also matches the timing of increased sand accumulation in the region and likely coincides with Neoglacial to Little Ice Age ice advances, or even enhanced dust activity in the last decades.

Explosion characteristics of AlH3 dust cloud with varying micron particle sizes

The explosion characteristics of AlH3 dust clouds with varying micron particle sizes are investigated in this paper. The explosion mechanism of AlH3 dust clouds is initially explored. The results indicate that the activation energy for hydrogen evolution shows an increasing trend with the AlH3 particle size, and both of these values are comparable to the 30 kJ/mol desorption energy of hydrogen from large AlH3 clusters. Due to the rapid dehydrogenation rate and small-size residual aluminum core, fine AlH3 particles exhibit a continuous gas-phase flame and fast propagation velocity. With increasing particle size, the lower dehydrogenation rate, reduced specific surface area, and higher volume heat capacity contribute to a higher level of incomplete reaction. Consequently, large micro-sized AlH3 particles display a discrete flame, slower flame velocity, and lower explosion pressure. The flame delamination phenomenon is not observed in our experiments on AlH3 dust clouds.

Enrichment of Phosphates, Lead, and Mixed Soil‐Organic Particles in INPs at the Southern Great Plains Site

AbstractIce nucleating particles (INPs) are rare particles that initiate primary ice formation, a critical step required for subsequent important cloud microphysical processes that ultimately govern cloud phase and cloud radiative properties. Laboratory studies have found that organic‐rich dusts, such as those found in soils, are more efficient INPs compared to mineral dust. However, the atmospheric relevance of these organic‐rich dusts are not well understood, particularly in regions with significant agricultural activity. The Agricultural Ice nuclei at the Southern Great Plains field campaign (AGINSGP) was conducted in rural Oklahoma to investigate how soil dusts contribute to INP populations in the Great Plains. We present chemical characterization of ambient and ice crystal residual particles from a single day of sampling, using single particle mass spectrometry (SPMS) and scanning microscopy. Ambient particles were primarily carbonaceous or secondary aerosol, while the fraction of dust particles was higher in the residual particles. We also observed an unusual particle type consisting of a carbonaceous core mixed with dust fragments on the surface, which was found in higher proportion in residuals. Dust particles measured during residual sampling contained greater proportions of phosphate (63 and 79) and lead (206Pb+). Strong sulfate signals were not seen in the residual dust particles measured by the SPMS, while nitrate was slightly depleted relative to ambient dust. This study shows that organic‐rich soils may be important contributors to the ambient INP population in agricultural regions.

An analysis of exogenous harmful substance exposure as risk factors for COPD and hypertension co-morbidity using PSM.

Some occupational and environmental exposures could increase the risk of chronic obstructive pulmonary disease (COPD) and hypertension in various work and living environments. However, the effect of exposure to multiple exogenous harmful substances on COPD and hypertension co-morbidities remains unclear. Participants were selected from eight hospitals in five provinces in China using a multistage cluster sampling procedure. Participants' demographic, exposure, and disease information were collected through questionnaires, spirometry, and blood pressure examinations. Demographic data were used as matching factors, and 1:1 matching between the exposed and non-exposed groups was performed by employing propensity score matching (PSM) to minimize the influence on the results. A one-way chi-squared analysis and multifactorial logistic regression were used to analyze the association between the exposure to exogenous harmful substances (metals and their compound dust, inorganic mineral dust, organic chemicals, and livestock by-products) and the co-morbidity of COPD and hypertension. There were 6,610 eligible participants in the final analysis, of whom 2,045 (30.9%) were exposed to exogenous harmful substances. The prevalence of co-morbidities of COPD and hypertension (6.0%) in the exposure group was higher than their prevalence in the total population (4.6%). After PSM, exogenous harmful substance exposure was found to be a risk factor for the co-morbidity of COPD and hypertension [odds ratio (OR) = 1.347, 95% confidence interval (CI): 1.011-1.794], which was not statistically significant before PSM (OR = 1.094, 95% CI: 0.852-1.405). Meanwhile, the results of different outcomes showed that the association between hypertension and exogenous harmful substance exposure was not statistically significant (OR = 0.965, 95% CI: 0.846-1.101). Smoking (OR = 4.702, 95% CI: 3.321-6.656), history of a respiratory disease during childhood (OR = 2.830, 95% CI: 1.600-5.006), and history of respiratory symptoms (OR = 1.897, 95% CI: 1.331-2.704) were also identified as risk factors for the co-morbidity of COPD and hypertension. The distribution of exogenous harmful substance exposure varies in the population, and the prevalence of co-morbidities is generally higher in susceptible populations. Exposure to exogenous harmful substances was found to be a key risk factor after adjusting for demographic confounders.

Application of Normalized Radar Backscatter and Hyperspectral Data to Augment Rangeland Vegetation Fractional Classification

Rangeland ecosystems in the western United States are vulnerable to climate change, fire, and anthropogenic disturbances, yet classification of rangeland areas remains difficult due to frequently sparse vegetation canopies that increase the influence of soils and senesced vegetation, the overall abundance of senesced vegetation, heterogeneity of life forms, and limited ground-based data. The Rangeland Condition Monitoring Assessment and Projection (RCMAP) project provides fractional vegetation cover maps across western North America using Landsat imagery and artificial intelligence from 1985 to 2023 at yearly time-steps. The objectives of this case study are to apply hyperspectral data from several new data streams, including Sentinel Synthetic Aperture Radar (SAR) and Earth Surface Mineral Dust Source Investigation (EMIT), to the RCMAP model. We run a series of five tests (Landsat-base model, base + SAR, base + EMIT, base + SAR + EMIT, and base + Landsat NEXT [LNEXT] synthesized from EMIT) over a difficult-to-classify region centered in southwest Montana, USA. Our testing results indicate a clear accuracy benefit of adding SAR and EMIT data to the RCMAP model, with a 7.5% and 29% relative increase in independent accuracy (R2), respectively. The ability of SAR data to observe vegetation height allows for more accurate classification of vegetation types, whereas EMIT’s continuous characterization of the spectral response boosts discriminatory power relative to multispectral data. Our spectral profile analysis reveals the enhanced classification power with EMIT is related to both the improved spectral resolution and representation of the entire domain as compared to legacy Landsat. One key finding is that legacy Landsat bands largely miss portions of the electromagnetic spectrum where separation among important rangeland targets exists, namely in the 900–1250 nm and 1500–1780 nm range. Synthesized LNEXT data include these gaps, but the reduced spectral resolution compared to EMIT results in an intermediate 18% increase in accuracy relative to the base run. Here, we show the promise of enhanced classification accuracy using EMIT data, and to a smaller extent, SAR.

In Situ Lung Dust Analysis by Automated Field Emission Scanning Electron Microscopy With Energy Dispersive X-ray Spectroscopy: A Method for Assessing Inorganic Particles in Lung Tissue From Coal Miners.

Overexposure to respirable coal mine dust can cause severe lung disease including progressive massive fibrosis (PMF). Field emission scanning electron microscopy with energy dispersive x-ray spectroscopy (FESEM-EDS) has been used for in situ lung dust particle analysis for evaluation of disease etiology. Automating such work can reduce time, costs, and user bias. To develop and test an automated FESEM-EDS method for in situ analysis of inorganic particles in coal miner lung tissue. We programmed an automated FESEM-EDS procedure to collect particle size and elemental data, using lung tissue from 10 underground coal miners with PMF and 4 control cases. A statistical clustering approach was used to establish classification criteria based on particle chemistry. Data were correlated to PMF/non-PMF areas of the tissue, using corresponding brightfield microscopy images. Results for each miner case were compared with a separate corresponding analysis of particles recovered following tissue digestion. In situ analysis of miner tissues showed higher particle number densities than controls and densities were generally higher in PMF than non-PMF areas. Particle counts were typically dominated by aluminum silicates with varying percentages of silica. Compared to digestion results for the miner tissues, in situ results indicated lower density of particles (number per tissue volume), larger size, and a lower ratio of silica to total silicates-probably due to frequent particle clustering in situ. Automated FESEM-EDS analysis of lung dust is feasible in situ and could be applied to a larger set of mineral dust-exposed lung tissues to investigate specific histologic features of PMF and other dust-related occupational diseases.

The seasonal variation of Asian dust, anthropogenic PM, and their sources in Dushanbe, Tajikistan

Central Asia's arid climate and growing population make it susceptible to air pollution from mineral dust and anthropogenic sources. To assess the impact of these pollution sources on local air quality, the chemical composition of PM10 aerosol particles was collected within a year at Dushanbe, Tajikistan. Primary sources of the pollutants, their impact on PM10 composition, and their seasonal trends were assessed. The measurement approach employed analysis of trace metals, ions, organic compounds, laboratory investigations, diagnostic ratio calculations, all complemented by positive matrix factor analysis. The results reveal that for about 70% of the year, PM10 levels (80 ± 55 μg m−3 as the annual average) in Dushanbe were higher than the WHO limits, with varying levels during the seasons. Summer concentrations peaked up to 434 μg m−3 due to a combined mineral and road dust influence. Interestingly, winter concentrations reached 152 μg m−3 due to strong contributions (about 64%) from residential heating and fossil fuel combustion, often triggered during sub-10 °C temperatures. Mineral dust events were associated with elevated concentrations of trace metals, including Zn and Pb, alongside organic carbon and high-chain n - alkanes. During such events, Ca/Fe, Ca/Al ratios exceeded those of Saharan dust, suggesting a high salt content in Asian dust, potentially influenced by dried-off lake emissions. It was striking to observe that winter periods exhibited concerning levels of carcinogenic PAHs, such as benzo(b)fluoranthene (<25 ng m−3) and benzo[a]pyrene (<12 ng m−3, BaP), with average values of 4.1 ± 5.9 ng m−3 (BaP) that significantly exceed WHO recommendations. The high PM10 and PAH exposure could pose severe health risks, necessitating collective attention from the local authorities in developing new mitigation strategies concerning the reduction of emissions from residential heating of coal and wood in winter to curb combustion emissions and reduce exposure.

Modified sodium alginate-based three-dimensional network hydrogel dust suppressant: Preparation, characterization, and performance

Chemical dust suppression is typically associated with high economic costs, unclear efficacy, and poor degradability. In this study, sodium alginate (SA) was extracted from kelp and cross-linked with polyvinyl alcohol (PVA) and polyacrylamide (PAM). Sulfonated castor oil (CAS) was subsequently added to generate a three-dimensional network hydrogel dust suppressant (PVA-SA-PAM/CAS). Using single-factor experiments, the optimal reaction temperature (60 °C) and dosages of PVA, PAM, and the cross-linking agent (2.5, 4.5, and 0.1 g, respectively) were determined. The viscosity and compressive strength of the prepared hydrogel were 86 mPa·s and 218 kPa, respectively, which meet the requirements for mine dust suppression. Various analyses revealed the hydrogel's reaction process and microstructure changes. Additionally, thermogravimetric experiments proved that the hydrogel had good thermal stability. The specific surface area and pore size of the hydrogel were 0.0278 m2/g and 11.8 nm, respectively, improving its adsorption capacity. Additionally, PVA-SA-PAM/CAS exhibited a good water retention rate. The dust suppression efficiency of PVA-SA-PAM/CAS was >98 % under strong winds (12 m/s). Moreover, the degradation rate of PVA-SA-PAM/CAS was 37 % after eight cycles (56 d) under environmental conditions. Therefore, PVA-SA-PAM/CAS exhibits good wetting, dust suppression, and degradation properties, which can effectively alleviate mine dust pollution.

Research on the explosion vent external composite disaster induced by dust explosion inside the dust collector

With the help of computational fluid dynamics (CFD) technology, this research focuses on the quantitative effects of the explosion venting area (S), static opening pressure of the vent (Pstat) and dust cloud concentration (CD) on the explosion overpressure, high-speed airflow and high-temperature flame in the explosion venting zone. The results show that the explosion disaster along the explosion venting zone in general shows an oscillating fluctuating trend of attenuation, and the closer to the explosion vent explosion disaster is more serious. The increase of S will enhance the nonlinear change of explosion disaster, and the change law of explosion overpressure is completely opposite to that of high-speed airflow and high-temperature flame. With the increase of Pstat, the coupling effect of air intake pipe and dust collector is strengthened, which further aggravates the spread of explosion disaster. The change of CD has both promoting and restraining effects on the spread of explosion disaster. The maximum overpressure (P), maximum wind speed (V), maximum flame speed (Fs) and maximum flame distance (Fd) in the explosion venting zone are 0.022 MPa, 494.5 m/s, 112.9 m/s and 10.9 m, respectively, and the venting safety distance is more than 11 m. In addition, the degree of impact on explosion disaster is in the following order: Pstat > A > CD. This research can provide a reference basis for the effective prevention and control of the composite disaster external the explosion vent induced by dust explosion inside the dust collector.

Source and fate of atmospheric iron supplied to the subarctic North Pacific traced by stable iron isotope ratios

The availability of dissolved iron (Fe) limits primary production over some regions of the surface ocean, especially in regions such as the subarctic North Pacific. In this work, we use Fe stable isotope ratios (δ56Fe) in bulk and size-fractionated marine aerosol particles and dissolved Fe of surface seawater in the subarctic North Pacific on Japanese GEOTRACES cruise GP02 (Summer 2017) as a tracer to clarify the relative contribution of combustion and natural Fe in both marine aerosol particles and surface seawater. The bulk aerosols collected in the coastal regions of both East Asia and western North Pacific have total δ56Fe values that are as low as −0.5 ‰ when compared to crustal (+0.1 ‰), with both the water-soluble phase and the fine particles even more fractionated (as low as −1.9 and −2.8 ‰, respectively). The negative correlation between the aerosol δ56Fe signatures and the enrichment factors of Fe and other elements dominated by anthropogenic sources (e.g., lead and cadmium) in these coastal regions indicates the presence of Fe emitted from high-temperature combustion sources, such as coal combustion and metal smelting. In these regions, combustion Fe accounts for 4–13 and 13–45 % of the total and water-soluble aerosol Fe, respectively. The results demonstrate that soluble aerosol Fe sourced from combustion Fe can be equivalent to that sourced from natural dust Fe in these coastal regions. By contrast, the aerosol particles in pelagic regions were near crustal δ56Fe in all particle size fractions, indicating the dominance of natural Fe and little to no combustion Fe. The relationships among the fractional Fe solubility, major ion concentration, Fe species, and δ56Fe indicate that the presence of combustion Fe is the dominant reason for the solubility increase in the coastal regions and that the atmospheric processing of mineral dust during transport is more important in the pelagic regions. The dissolved Fe of the surface seawater at 10 m depth had a consistently higher δ56Fe by up to +1.5 ‰ than that of the simultaneously collected water-soluble aerosol Fe. The pattern of the elevated δ56Fe in the surface seawater corresponds to decreasing Fe concentrations and can be approximated by Rayleigh fractionation; we attribute these elevated surface δ56Fe values to the effect of biological uptake. New Fe fluxes from both the atmosphere and deeper depths are limited at least in summer compared with the biological uptake in the open ocean of the subarctic North Pacific.

Contribution of Saharan dust to chemical weathering fluxes and associated phosphate release in West Africa

Huge amounts of mineral dust are produced in northern Africa, representing the largest source of aerosols worldwide. Transatlantic dust transport is known to fertilize soils as far as in the Amazon Basin. Yet, the influence of Saharan dust on chemical weathering fluxes and associated nutrient release in West Africa remains largely overlooked. To address this issue, we analysed clay fractions (<2 µm) of river sediments (n = 37) from across the Niger River basin - the largest river system in West Africa - using neodymium and hafnium isotope compositions as proxies for provenance (εNd) and chemical weathering (ΔεHf CLAY).Compared to previously published data for corresponding sand fractions, measured εNd values indicate significant size-dependent decoupling for Nd isotopes in most samples, with εNd differences between clay and sand fractions yielding values as great as ∼26 ε-units. Using mixing models, we show that this discrepancy reflects the overwhelming presence in the studied clay fractions of Harmattan dust blown from the Bodélé Depression in Chad, which we estimate to account for about 40 % of the fine-grained sediment load exported to the Gulf of Guinea. Additionally, significant ΔεHf CLAY variability occurs across the Niger catchment, partly explained by the presence of zircon in clay-size fractions, but also by preferential alteration of dust-borne accessory phosphate minerals in the subtropical regions of the watershed.Based on these results, we propose that Saharan dust plays a major role in controlling regional patterns of chemical weathering in West Africa, suggesting that enhanced wet deposition of mineral dust in shield areas dominated by transport-limited weathering regime can result in a large increase in weatherability and associated release of phosphorus. These findings have general implications for the importance of mineral aerosols in controlling sediment yield and the supply of weathering-derived nutrients to continental areas bordering large subtropical deserts worldwide.

Uncertainties in laboratory-measured shortwave refractive indices of mineral dust aerosols and derived optical properties: a theoretical assessment

Uncertainties in laboratory-measured shortwave refractive indices of mineral dust aerosols and derived optical properties: a theoretical assessment

Women in Coal Mining-Radiographic Findings of Women Participants in the Coal Workers' Health Surveillance Program 1970-2022.

Objective: To describe the work experience and respiratory health of women coal miners in the United States using Coal Workers' Health Surveillance Program (CWHSP) data. Methods: Analysis included CWHSP participants with self-reported sex of female between January 1, 1970, and December 31, 2022, and examined radiographic surveillance, demographics, and job history. National Institute for Occupational Safety and Health-certified physicians classified chest radiographs. Results: Among 8,182 women participants, most worked <10 years and a majority reported working in non-dusty jobs. Among 3,392 with ≥1 year of coal mining tenure, 18 (0.5%) had evidence of pneumoconiosis, with no cases of progressive massive fibrosis. Conclusion: Women coal miners participating in the CWSHP had short mining careers and low pneumoconiosis prevalence. Few worked in the most dusty jobs, indicating limited exposure to coal mine dust. This underscores the need to explore women's roles in mining, and for improved gender-specific employment reporting. Such changes can enhance health and work conditions for women in male-dominated industries.

Global aerosol models considering their spatial heterogeneities based on AERONET measurements

The imprecision inherent in aerosol models poses a significant challenge in satellite- and surface- based aerosol retrieval. The correct classification of global aerosol types and understanding of their spatial heterogeneity are prerequisites for accurately deriving aerosol optical and microphysical properties and assessing their impacts on climate, air quality, and human health. In this study, a deep clustering algorithm is developed and employed to classify global aerosol types by using >160,000 records of AERONET measurements at 411 sites during 2000–2020. The proposed algorithm utilizes deep learning techniques to optimize the feature space of input variables, thereby improving the distinguishability among various aerosol types. This algorithm outperforms the commonly used K-means method with 77.4% of AERONET sites experiencing increased explained variance. Based on their unique properties (e.g., single scattering albedo, complex refractive index and dust ratio, etc.) and geographic distribution, global aerosols are classified into six types: mineral dust, smoke, two urban aerosols with different particle sizes, and two mixtures with different dominant components. The spatial heterogeneity of aerosol optical/microphysical properties is distinctly presented in our clustering results. Through the subdivision of the global domain into 11 sub-regions, a comprehensive elucidation has been undertaken to delineate the variances in volume size distribution, absorption, and scattering characteristics exhibited among disparate aerosol types, as well as within a same aerosol category. These new understandings of aerosol models and their spatial heterogeneities in this study will be highly helpful to update or optimize aerosol retrieval algorithms in the future.

Aerosol sources and transport paths co-control the atmospheric bacterial diversity over the coastal East China Sea

Airborne bacteria along with chemical composition of aerosols were investigated during five sampling seasons at an offshore island of the East China Sea. Bacterial diversity was the lowest in spring, the highest in winter, and similar between the autumns of 2019 and 2020, suggesting remarkably seasonal variation but little interannual change. Geodermatophilus (Actinobacteria) was the indicator genus of mineral dust (MD) showed higher proportion in spring than in other seasons. Mastigocladopsis_PCC-10914 (Cyanobacteria) as the indicator of sea salt (SS) demonstrated the highest percentages in both autumns, when the air masses mainly passed over the ocean prior to the sampling site. The higher proportions of soil-derived genera Rubellimicrobium and Craurococcus (both Proteobacteria) and extremophile Chroococcidiopsis_SAG_2023 (Cyanobacteria) were found in summer and winter, respectively. Our study explores the linkage between aerosol source and transport path and bacterial composition, which has implication to understanding of land-sea transmission of bacterial taxa.

Study on the degree of influence of coal chemical structure on its wetting characteristics

The wettability of coal plays a crucial role in determining the effectiveness of mine dust reduction, coal flotation, and coal water slurry preparation. This property is influenced by various factors, including coal structure and liquid properties. To investigate the impact of coal’s chemical properties on its wetting behavior, we employed different experimental to characterize the chemical structures of six types of coal. Utilizing contact angle experiments and gray slope correlation analysis, we determined the correlation between each chemical structure parameter and the wetting characteristics of the coal samples. Our findings revealed that 6#Yangquan anthracite has the lowest wettability and its contact angle is 85.3°. Within the coal’s functional group structure, the CH2 symmetric stretching vibration exhibited the highest correlation (0.944) with coal wetting properties. Regarding the elemental composition of coal, oxygen exhibited a higher correlation with coal-wetting properties (carbonyl oxygen structure, 0.788; phenol hydroxyl and ether oxygen bond, 0.798; carboxyl oxygen structure, 0.734). In the carbon skeleton structure of coal, the protonated aryl carbon exhibited the highest correlation degree of 0.944. These results offer insights into the selection of evaluation indices for assessing the influence of coal wetting characteristics and optimizing the hydrophilic and hydrophobic features of the coal surface.

Photoenhanced sulfate formation by the heterogeneous uptake of SO2 on non-photoactive mineral dust

Abstract. Heterogeneous uptake of SO2 on mineral dust is a predominant formation pathway of sulfates, whereas the contribution of photo-induced SO2 oxidation to sulfates on the dust interfaces still remains unclear. Here, we investigated heterogeneous photochemical reactions of SO2 on five mineral oxides (SiO2, kaolinite, Al2O3, MgO, and CaO) without photocatalytic activity. Light enhanced the uptake of SO2, and its enhancement effects negatively depended on the basicity of mineral oxides. The initial uptake coefficient (γ0,BET) and the steady-state uptake coefficient (γs,BET) of SO2 positively relied on light intensity, relative humidity (RH), and O2 content, while they exhibited a negative relationship with the initial SO2 concentration. Rapid sulfate formation during photo-induced heterogeneous reactions of SO2 with all mineral oxides was confirmed to be ubiquitous, and H2O and O2 played key roles in the conversion of SO2 to sulfates. In particular, triplet states of SO2 (3SO2) were suggested to be the trigger for photochemical sulfate formation. Atmospheric implications supported a potential contribution of interfacial SO2 photochemistry on non-photoactive mineral dust to atmospheric sulfate sources.