Radiative transfer modeling of the low-mass proto-binary system, IRAS 4A1 and 4A2.

Characterization, sources, and driving factors of particulate matter (PM) pollution in a desert hinterland city: Insights from Hotan, China.

The sintering process represents a primary source of dust, SO2, NOx, and CO2 emissions in steel mills. Utilizing high-grade concentrate with low impurity content can directly reduce slag generation at the source, thereby decreasing fuel consumption and minimizing associated emissions. This study investigated the physicochemical properties, microstructure, and elemental distribution of hematite concentrates (H2 and H3) and H1 sinter fines. Sinter pot tests were conducted to evaluate the effects of blending these two concentrates on sintering performance and key quality indices. Microstructural analysis and quantitative phase composition statistics of the sintered products were performed to elucidate the mechanisms by which these concentrates influence sintering outcomes. Results demonstrated that replacing 33% H1 sinter fines with 33% H2 or H3 concentrates reduced the tumbler index from 73.6% to 68.5% and 73.2%, respectively. The productivity coefficient decreased to 68.5% and 73.2%, while solid fuel consumption increased from 73.9 kg/t to 90.5 kg/t and 81.2 kg/t. RI declined from 80.0% to 77.9% and 78.4%, whereas RDI improved from 72.9% to 76.8% and 75.8%.

Abstract Substructure in the interstellar medium (ISM) is crucial for establishing the correlation between star formation and feedback and has the capacity to significantly perturb stellar orbits, thus playing a central role in galaxy dynamics and evolution. Contemporary surveys of gas and dust emission in nearby galaxies resolve structure down to ∼10 pc scales, demanding theoretical models of ISM substructure with matching fidelity. In this work, we address this need by quantitatively characterizing the gas density in state-of-the-art magnetohydrodynamic simulations of disk galaxies that resolve parsec to kiloparsec scales. The TIGRESS-NCR framework we employ includes sheared galactic rotation, self-consistent star formation and feedback, and nonequilibrium chemistry and cooling. We fit simple analytic models to the one-point spatial, two-point spatial, and two-point spatiotemporal statistics of the surface density fluctuation field. We find that for both solar neighborhood and inner-galaxy conditions, (i) the surface density fluctuations follow a log-normal distribution, (ii) the linear and logarithmic fluctuation power spectra are well approximated as power laws with indices of ≈−2.2 and ≈−2.8, respectively, and (iii) lifetimes of structures at different scales are set by a combination of feedback and effective pressure terms. Additionally, we find that the vertical structure of the gas is well modeled by a mixture of exponential and sech 2 profiles, allowing us to link the surface density statistics to those of the volume density and gravitational potential. We provide convenient parameterizations for incorporating realistic ISM effects into stellar-dynamical studies and for comparison with multiwavelength observations.

Abstract We present Atacama Large Millimeter/submillimeter Array observations of multiwavelength dust emissions at 3.1 and 1.3 mm, along with molecular line emissions of CO(2–1), CO(3–2), 13 CO(3–2), and C 18 O(3–2) at spatial resolutions of 7–45 au toward the protoplanetary system AS 205. The dust emissions exhibit two distinct components of AS 205 N and AS 205 S, separated by 1 . ″ 3. While gas kinematics within the dust disk regions are dominated by Keplerian rotation, the more extended gas emission displays complex morphology and kinematics strongly affected by the binary gravitational interaction in the outer regions. The stellar masses of AS 205 N and AS 205 S are estimated at 0.78 ± 0.19 and 1.93 ± 0.86 M ⊙ , respectively. Azimuthal variation is observed in the spectral index distribution of both disks. In AS 205 N, the spectral index minimum in the southwest is coincident with the peaks of CO(2–1), CO(3–2), and 13 CO(3–2) integrated intensity and the relative position of its southern counterpart. On the other hand, the spectral index distribution in AS 205 S exhibits two prominent maxima, with the one in the northeast aligning with the peak of 13 CO(3–2), and the peak in the south coinciding with local maxima in CO(2–1) and CO(3–2) azimuthal profiles. These results suggest a correlation between dust grain size and/or optical depth with the gas distributions. Dust trapping along the spiral arms possibly contributes to the spectral index minima in AS 205 N; however, the observed asymmetry across both disks suggests the involvement of additional mechanisms.

Abstract We present component-separated polarization maps of the cosmic microwave background (CMB) and Galactic thermal dust emission, derived using data from the BICEP/Keck experiments through the 2018 observing season and Planck. By employing a maximum-likelihood method that utilizes observing matrices, we produce unbiased maps of the CMB and dust signals. We outline the computational challenges and demonstrate an efficient implementation of the component map estimator. We show methods to compute and characterize power spectra of these maps, opening up an alternative way to infer the tensor-to-scalar ratio from our data. We compare the results of this map-based separation method with the baseline BICEP/Keck analysis. Our analysis demonstrates consistency between the two methods, finding an 84% correlation between the pipelines.

Abstract. The Yinchuan metropolitan area in northwest China, situated between the Tengger and Ulan Buh Deserts, is influenced by both natural dust and anthropogenic emissions. However, the evolution of fine particulate matter (PM2.5) and its interaction with ozone (O3) under the region's arid climate remain poorly understood. This study integrates decadal observations (2015–2025) with in-situ measurements using an Aerosol Chemical Speciation Monitor and a Vocus Proton Transfer Reaction Mass Spectrometry during summer 2025 to elucidate the changing PM2.5–O3 relationship and sources of organic aerosols. A pronounced shift was identified: Phase I (2015–2018) featured a rapid decline in PM2.5 accompanied by a sharp O3 increase, while Phase II (2019–2025) exhibited stabilized PM2.5 and plateaued O3, indicating reduced O3 sensitivity to particulate controls. The average non-refractory PM2.5 concentration (16.8 µg m−3) was significantly lower than in eastern Chinese megacities, with organics accounting for ∼ 60 %. Positive matrix factorization resolved three organic aerosol factors, revealing dominant secondary organic aerosols (SOA, ∼ 74 %) derived from prolonged photochemical aging. Volatile organic compound analysis showed that anthropogenic and biogenic precursors, including urban terpenes and aromatic oxidation products jointly contributed to SOA formation. Back-trajectory and potential source analyses indicated that Yinchuan's summer air masses were mainly locally recirculated, with limited influence from long-range transport. These results demonstrate a regional transition toward SOA-dominated fine particles and decoupled PM2.5–O3 dynamics under cleaner conditions, highlighting the need for integrated VOC and oxidant controls to mitigate co-occurring O3 and PM2.5 pollution in arid northwest China.

Abstract The evolution of planet-forming regions in protoplanetary disks is of fundamental importance to understanding planet formation. Disks with a central deficit in dust emission, a “cavity,” have long attracted interest as potential evidence for advanced disk clearing by protoplanets and/or winds. Before JWST, infrared spectra showed that these disks typically lack the strong molecular emission observed in full disks. In this work, we combine a sample of 12 disks with millimeter cavities of a range of sizes (∼2–70 au) and different levels of millimeter and infrared continuum deficits. We analyze their molecular spectra as observed with MIRI on JWST, homogeneously reduced with the new JDISCS pipeline. This analysis demonstrates a stark dichotomy in molecular emission where “molecule-rich” (MR) cavities follow global trends between water, CO, and OH luminosity and accretion luminosity as in full disks, while “molecule-poor” (MP) cavities are significantly subluminous in all molecules except sometimes OH. Disk cavities generally show subluminous organic emission, higher OH/H 2 O ratios, and suggest a lower water column density. The subthermal excitation of CO and water vibrational lines suggests a decreased gas density in the emitting layer in all cavities, supporting model expectations for C 2 H 2 photodissociation. We discover a bifurcation in the infrared index (lower in MR cavities) suggesting that the molecular dichotomy is linked to residual μ m-size dust within millimeter disk cavities. Put together, these results suggest a feedback process between dust depletion, gas density decrease, and molecule dissociation. Disk cavities may have a common evolutionary sequence where MR switch into MP over time.

Abstract Star formation occurs within dusty molecular clouds that are then disrupted by stellar feedback. However, the timing and physical mechanisms that govern the transition from deeply embedded to exposed stars remain uncertain. Using the STARFORGE simulations, we analyze the evolution of “embeddedness,” identifying what drives emergence. We find the transition from embedded to exposed is fast for individual stars, within 1.3 Myr after the star reaches its maximum mass. This rapid transition is dominated by massive stars, which accrete while remaining highly obscured until their feedback eventually balances, then overcomes, the local accretion. For these massive stars, their maximum mass is reached simultaneously with their emergence. Once these stars are revealed, their localized, pre-supernova feedback then impacts the cloud, driving gas clearance. Because massive stars dominate the luminosity, their fast, local evolution dominates the light emergence from the dust. We calculate the dependence of these processes on the mass of the cloud and find that emergence always depends on when massive stars form, which scales with the cloud’s free-fall time. We also measure the evolution of dust and H α luminosities, where for ∼2 Myr, these tracers outshine the emerging stellar continuum, reaching their peak when gas and dust remain tightly coupled to the massive stars. These results closely resemble observationally observed lifetimes, tying the observable dust and line emission directly to the same localized processes that drive stellar emergence, evidence that our simulated de-embedding physics is representative of real star-forming regions. Thus, because the initial embedding of the most luminous stars is highly local, the emergence of stars is a faster, earlier, more local event than the overall disruption of the cloud by gas expulsion.

Dust emissions from arid and semiarid regions influence climate, biogeochemical cycles, and human health. Patagonia is one of the largest dust sources in the Southern Hemisphere, yet the contribution of urban activities to total particulate matter (PM) emissions remains poorly quantified. We analyzed a 12‐year record of daily PM concentrations from three sites in Puerto Madryn, Argentina, representing background, urban, and industrial environments. Our objectives were to quantify long‐term PM dynamics, identify and distinguish natural and anthropogenic sources using a particle‐trajectory model and meteorological data, and assess their relative contributions to PM load. We evaluated temporal variability, meteorological controls, and the origin of PM plumes using the HYSPLIT model. The results show that mean PM concentrations were highest at the industrial site and lowest at the background site, with pronounced peaks during winter months. Trajectory analysis indicated that most PM originated from arid regions west of Puerto Madryn, while local industrial and urban activities contributed substantially during specific events. These findings highlight the combined influence of natural and anthropogenic sources on PM dynamics in coastal Patagonia.

Abstract Tungsten co-deposited layers in fusion devices are a significant potential source of plasma-contaminating dust. This study investigates the mechanisms of dust release from helium–tungsten (He–W) and deuterium–tungsten (D–W) layers under high-density steady-state plasma and ELM-like plasma pulse superposition. High-speed imaging revealed different emission behaviors: the D–W layer, featuring pre-existing blisters, released dust immediately upon plasma exposure, while the He–W layer showed a delayed emission requiring damage accumulation from several pulses. Post-mortem SEM analysis confirmed distinct surface exfoliation corresponding to these behaviors. The immediate release of D–W dust was identified as the rupture of inherently fragile blisters. In contrast, the delayed release of He–W dusts resulted from subsurface flaking, initiated by horizontal cracks forming from the interconnection of internal nano-cavities. Both layers produced substantial dust, leading to much higher erosion rates than that of pristine tungsten. These results demonstrate that the trapped gas species fundamentally dictates the co-deposited layer’s microstructure and subsequent dust emission pathway, establishing these layers as a critical and rapid dust source under transient plasma loads.

Currently, there is a lack of systematic and quantitative analytical tools for dust emission control in open-pit iron mines. To address this research gap, this study constructs a comprehensive evaluation index system by integrating the Analytic Hierarchy Process (AHP) and the fuzzy comprehensive evaluation (FCE) method. The framework includes four first-level indicators, 12 s-level indicators and 30 third-level indicators. The structural design was informed by laws and regulations, the relevant literature and the principle of dust hierarchical control to ensure the theoretical and empirical basis for the selection of indicators. The evaluation process was based on on-site monitoring data and production ledgers from the open-pit iron mine of the Shuichang Mine, as well as the results of multiple rounds of consultation by the Delphi method group composed of 30 experts in related industries. The results show that the comprehensive score of the mine is 87.14 points, and the overall prevention and control is effective. But the performance of each dimension is unbalanced: fundamental data on production processes scored highest, while individual exposure and protection measures were relatively weak, indicating that the personnel protection link needs to be strengthened. Sensitivity analysis further verified the structural stability of the index system and identified the ventilation and dust removal system as a key driving factor. This framework can provide quantitative decision support for mine managers, enhancing the precision and overall effectiveness of dust control through the accurate identification of weaknesses and optimized resource allocation.

The spatial distribution of risk elements and the impacts of acidification on mountain soils affected by anthropogenic emissions are poorly understood due to the limited number of corresponding case studies. This work examines the distribution of Ca, Mn, and Zn in topsoils of the mountain terrains of the Beskids along the eastern part of the Czech-Polish state border, which have been locally impacted by emissions of acid gases and dust from metallurgy in the 20th century. Samples of the top stratum of mineral soil horizons, rock fragments, and birch leaves were collected from 140 sites within an approximately 12 x 12 km area in mountain ridges and slopes, primarily covered by forests. Concentrations of Mn and Zn in soils and leaves were subjected to interelement correlations and spatial distribution analyses. Soil Mn and Zn concentrations were corrected using Fe as a lithogenic reference element to correct a part of natural geochemical variability of the bedrock. While topsoil Mn and Zn concentrations directly reflect contamination, the uptake of Mn and Zn by birch was also enhanced by low soil Ca levels. The probabilistic nature of the factors controlling soil contamination and the topographically-driven distribution of emission loads necessitate the use of less conventional data-mining tools. The variable probability that emission contamination has been really recorded in individual environmental samples requires the application of robust regression, quantile statistics, and/or rational data post-stratification. Visual examination of geochemical maps with quantile-classified layers and geographically weighted regression (GWR) proves advantageous in data mining, because conventional hotspot analysis using geostatistics is weakened by considerable spatial noise. Point contamination of the Beskid soils is maximal on slopes exposed to Třinec at a distance of approximately 15 km and at elevations between 600 and 700 m a.s.l. The spatial heterogeneity of soil Mn and Zn concentrations arises from uneven emission scavenging depending on landscape topography, horizontal emission deposition, and the translocation of Ca and Mn ions downslopes.

Abstract Vegetated sand dunes are not typically considered to be significant sources of dust because of coarse grain sizes and high vegetation cover. Yet, plumes of dust have been observed from vegetated dune fields, and wind tunnel experiments show the potential for interdunes to emit dust. The partially vegetated southwest Kalahari is one such dune field that is vulnerable to climate‐driven land degradation and vegetation cover change and has been posited as a potential future dust source. In this study, we monitor the post‐fire de‐vegetated state of 11 interdunes to investigate the dust emission potential and erodibility controls on emission. Findings suggest that there is little emission of dust despite a fine‐grain component (up to 30% of resident grains <62.5 μm) and a lack of vegetation, even with high velocity wind events (>7 m s −1 ) post‐fire. Erosive wind events were less frequent compared to other dust‐producing regions, with wind speeds generally under 7 m s −1 . Five high wind speed events over 7 m s −1 were recorded in September 2022, the month immediately following burning, but even then, only one event had a concurrent increase in aerosol concentration. This is indicative of other erodibility factors limiting dust emission. These include high (>50%) burned debris cover in the immediate post‐fire period and evidence of biological soil crusts that survived burning. Both protect the surface after fire whilst the natural vegetation cover recovers. Combined, the general low wind speeds, high initial surface cover, and the protective effect of biocrusts result in a low probability of the southwest Kalahari emitting dust post‐fire. However, fine‐grain sizes and low vegetation cover under drought and high grazing may lead to conditions conducive for dust emission.

A bio-based salt-tolerant hydrogel dust suppressant for long-term control of dust emissions from saline-alkali soils.

Impact of a large-scale desert photovoltaic power plant on aeolian saltation and dust emission

Airborne particulate matter enriched with heavy metals constitutes a significant health threat across the developing world. To investigate the distribution, sources, and health risks of PM2.5-bound heavy metals, ambient samples were collected in Baoding city from 2014 to 2022 and analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Results showed that the annual mean PM2.5 concentration in Baoding exceeded the World Health Organization (WHO) Interim Target-1. PM2.5 levels generally declined from 2014 to 2022, with seasonal variation following the order: winter > autumn > spring > summer. Heavy metal concentrations peaked in winter, significantly exceeding those in spring, autumn, and summer, the latter exhibiting the lowest metal loading. Despite long-term air pollution controls, the annual average concentration of carcinogenic Cr(VI) may still surpass the WHO limit. Five major PM2.5 sources were identified: coal combustion, secondary aerosols, vehicle emissions, dust, and industrial emissions. Coal combustion was the dominant source before 2017, after which secondary aerosols became predominant. Secondary aerosols also constituted the primary source in summer. Vehicle emissions and secondary aerosols contributed more to PM2.5 in summer than in other seasons, while dust contributions were more pronounced in spring. Monte Carlo simulations indicated that PM2.5-bound heavy metals pose non-carcinogenic risks to different populations at varying probabilities, with children exhibiting higher non-carcinogenic risks than adults. Manganese contributed most to non-carcinogenic risk. For carcinogenic risk, heavy metals showed a low probability of significant carcinogenic risk (SCR) or a high probability of acceptable risk (ACR). Carcinogenic risk probability ranked as: adult males > adult females > children, suggesting adult males may face the highest carcinogenic risk from PM2.5-bound heavy metals. Among the five assessed metals, carcinogenic risk probability decreased in the order: As > Cr(VI) > Cd > Co > Ni, with As and Cr(VI) as dominant contributors. Both carcinogenic and non-carcinogenic risks were higher in winter than in other seasons. This study demonstrates that while coordinated air pollution controls in the Beijing-Tianjin-Hebei region have achieved some outcomes, Mn, Cr, and As still present notable potential health risks, requiring urgent attention.

Temporal asymmetry in the flux variability of active galactic nuclei (AGNs) offers key insights into the physical mechanisms driving AGN variability. In this study, we investigated the variability of the torus by analyzing temporal asymmetry in the mid-infrared (MIR) continuum. We compared ensemble structure functions between the brightening and dimming phases for AGNs at 0.15 < z < 0.4, using monitoring data in the optical from the Zwicky Transient Facility and in the MIR from the Near-Earth Object Wide-field Infrared Survey Explorer. We found that AGNs with bluer optical-to-MIR colors exhibit positive temporal asymmetry in the MIR, indicating that their variability amplitude is larger when brightening. Conversely, those with redder colors show negative asymmetry, exhibiting larger variability amplitude when decaying. However, there is no significant temporal asymmetry in the g band variability driven by the accretion disk, suggesting that the temporal asymmetry in the MIR continuum primarily originates from intrinsic processes in the torus instead of the reflection of the ultraviolet-optical variability from the accretion disk. Analysis of the composite light curves revealed that AGNs with bluer optical-to-MIR colors tend to brighten gradually in the MIR, leading to the observed temporal asymmetry. This finding suggests that hot-dust-rich AGNs evolve with a gradual decline in hot dust emission, while hot-dust-poor AGNs are associated with a steady increase.

Abstract Over recent decades, North African dust storms have undergone marked variability, reflecting complex interactions between regional climate processes and environmental change. Using four decades (1984–2023) of visibility‐based observational records, we examine regional and seasonal trends in dust storm frequency across the Sahel and the Sahara, capturing their distinct dust dynamics. Results reveal a significant decline in dust activity in both regions, most pronounced during pre‐monsoon (MAM) and monsoon (JJA) seasons in the Sahel, and during post‐monsoon (SON) and dry season (DJF) in the Sahara. Integrating surface observations with local meteorology (precipitation, surface wind speed, vegetation) and climate indices (AMO, NAO, MEI), we find the Atlantic Multidecadal Oscillation (AMO) as the primary driver, with region‐specific effects: in the Sahel, AMO‐driven warming and rainfall increase vegetation, suppressing dust; in the Sahara, AMO intensifies the Saharan Heat Low (SHL) and elevates temperatures, modulating dust through atmospheric stability and wind patterns. Local meteorology further differentiates responses, with precipitation and Leaf Area Index (LAI) dominating dust variability in the Sahel, while SHL strength and surface winds are most influential in the Sahara. By explicitly separating the Sahel and Sahara and integrating multiple drivers, this study provides a more spatially resolved understanding of dust–climate link and suggests continued declines in North African dust storm activity under future warming. These findings offer critical constraints for improving dust emission projections in climate models.

Abstract Current climate models struggle to capture the mean state and variability of dust emissions. This is partially due to their inability to resolve convection, a consequence of their relatively coarse spatial resolution. Via analysis of output from an offline dust emission scheme forced with output from a global storm‐resolving model, we show that resolving convection doubles the contribution of the Sahel, an important dust source region sensitive to environmental change, to global dust emissions from 6.1% to 12.3% during its late monsoon season. Resolving convection induces an increase in friction velocity and a decrease in soil moisture, and thus enhances Sahelian dust emissions. These changes are due to improved representation of mesoscale convective systems associated with African Easterly Waves. These results demonstrate that high‐resolution modeling with resolved convection can improve understanding of the global dust cycle and how dust emissions are affected by a changing climate.