Trace elements (TEs) in the insoluble particles of surface snow are less affected by melting processes and can be used as environmental proxies to reveal natural and anthropogenic emissions. Here the first comprehensive study of the 16 TEs (Al, As, Ba, Bi, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Sr, Ti, U, V, and Zn) in insoluble particles (>0.45 μm) from surface snow samples collected at Urumqi Glacier No. 1 (UG1), Eastern Tien Shan, China, from February 2008 to January 2010 were presented. Results show that concentrations of most insoluble particulate TEs (TEs ᵢₙₛₒₗ) in the snow were higher in summer while lower in winter, due to the increasing particle inputs and melting processes. The abundances of As, Cr, Cu, Ni, Pb, and Zn in some samples were higher than those in surrounding urban soils, which might due to these TEs have further anthropogenic input beyond the already contaminated re-suspended urban soil particles and TEs were mainly enriched in particles with small grain size. Based on enrichment factor (EF) and principal component analysis (PCA), our results suggest that eight TEs (Al, Fe, Ti, Ba, Mn, Sr, U, and V) mainly came from mineral dust, while the remaining eight TEs (As, Bi, Cr, Cu, Ni, Pb, Sn, and Zn) were affected by coal combustion, mining and smelting of non-ferrous metals, traffic emissions, and the steel industry. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model suggests that pollutants might originate from Xinjiang province, Kazakhstan, and Kyrgyzstan. Moreover, UG1 received more significant inputs of particle-bound pollutants in summer than in winter due to the stronger convection and the prevailing valley wind that transports pollutants from the city of Urumqi.

Addressing the presence of rutile nanoparticles (NPs) in the air is a work in progress, and the development of methodologies for the identification of NPs in atmospheric dust is essential for the assessment of its toxicological effects. To address this issue, we selected the fast growing desertic city of Hermosillo in northern Mexico. Road dust (n = 266) and soils (n = 10) were sampled and bulk Ti-contents were tested by portable X-ray fluorescence. NPs were extracted from atmospheric dust by PM₁.₀-PTFE filters and further characterized by Confocal Raman Microscopy, Energy-dispersive X-ray spectroscopy (EDS) coupled to Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Results showed (i) the average concentration of Ti in road dust (3447 mg kg⁻¹) was similar to natural values and worldwide urban dusts; (ii) the bulk geochemistry was not satisfactory for Ti-NPs identification; (iii) 76% of the total extracted PM₁.₀ sample corresponded to NPs; (iv) mono-microaggregates of rutile NPs were identified; (v) ubiquitous polycyclic aromatic hydrocarbons (PAHs) were linked to NPs. The genotoxicity of rutile and PAHs, in connection with NPs content, make us aware of a crucial emerging environmental issue of significant health concern, justifying further research in this field.

Occurrence, behavior, and fate of 11 OPEs in multiple environmental matrices, which include air, rainwater, dustfall, paddy soil, irrigation water, and rice plants from nine subtropical paddy fields of South China, were investigated. The total concentrations of 11 OPEs (∑₁₁OPEs) in all matrices are generally higher in the urban areas than in rural areas, and they are higher in summer than in fall. However, both urban and rural areas showed a similar composition profile of OPEs, indicating that the OPEs come from similar sources in the two areas. Except for irrigation water, significant positive correlations of ∑₁₁OPEs were observed between air and the other five matrices. The exchange and partition of OPEs among air, soil, and water demonstrate that most of OPEs were transferred from air into water and soil, and from water into soil. Thus, the air may be an important source of OPEs in the paddy fields, and the soil may act as a principal environmental reservoir of OPEs. The contribution of air-soil exchange, atmospheric deposition (rainwater plus dustfall), and irrigation water to the total input fluxes of OPEs (2100 ± 980 ng/m²/day) reached an average of 19%, 38% (37% + 1%), and 43%, respectively. The water (rainwater plus irrigation water) is the primary medium transferring the OPEs into the paddy fields and contributed to the input flux by 80%. Output flux of OPEs via mature rice plants was about 220 μg/m², 2% of which were presented in rice, and the remaining 98% may be re-released into the environment through the pathway of straw turnover or burning. Dietary exposure via rice was much higher than inhalation exposure, dust ingestion, and dermal absorption via dust. However, no data shows that all of the intakes via the four exposure pathways could cause the risks to human health at present.

Antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) have become a critical global public health issue in this century. There is increasing evidence for the presence and transmission of ARGs by air transmission. In this research, ARGs and ARB in air conditioner filter dust (AC dust) and urine samples from 55 kindergarten children in 17 kindergartens and nearby 10 soil samples in Hong Kong were analyzed. The results showed the presence of 16 ARG subtypes and the mobile genetic element (MGE) intI1 in AC dust, and 12 ARG subtypes in the soil samples. ARGs presenting resistance to sulfonamide (6.9 × 10⁻³–0.17) (expressed as relative abundance of the 16 S rRNA genes) were most abundant followed by macrolides (1.8 × 10⁻³–3.3 × 10⁻²), sul1, sul2 (sulfonamide), ermF (macrolides) and intI1 genes in AC dust in 17 kindergartens. For soil samples, 12 ARG subtypes and the intI1 were detected, and the genes providing resistance to sulfonamide (1.6 × 10⁻³–2.7 × 10⁻¹) were the most abundant ARGs in the 10 soil samples, followed by tetracycline (ND–1.4 × 10⁻²). Multi-resistant bacteria with sul1, sul2, intI1, or tetQ were detected in all AC dust samples and some urine samples. Based on bacterial genera and ARG co-occurrence network analysis and Hong Kong’s special geographical location and cultural environment, there might be two origins for the ARGs detected in the kindergartens: β-lactam/macrolide ARGs mainly derived from human medicine use and tetracycline/sulfonamide ARGs mainly from other areas, as well as IntI1 may play a role in the spread of ARGs in Hong Kong. The widely detection of ARGs in AC dust in kindergartens in Hong Kong highlights the need for the improvement of management measures.

Continuous measurements of Black Carbon (BC) aerosol mass concentrations were carried at Dehradun (30.33°N, 78.04°E, 700 m amsl), a semi-urban site in the foothills of north-westHimalayas, India during January 2011–December 2017. We reported both the BC seasonal variations as well as mass concentrations from fossil fuel combustion (BCff) and biomass burning (BCbb) sources. Annual mean BC exhibited a strong seasonal variability with maxima during winter (4.86 ± 0.78 μg m⁻³) followed by autumn (4.18 ± 0.54 μg m⁻³), spring (3.93 ± 0.75 μg m⁻³) and minima during summer (2.41 ± 0.66 μg m⁻³). Annual averaged BC mass concentrations were 3.85 ± 1.16 μg m⁻³ varying from 3.29 to 4.37 μg m⁻³ whereas BCff and BCbb ranged from 0.11 to 7.12 μg m⁻³ and 0.13–3.6 μg m⁻³. The percentage contributions from BCff and BCbb to total BC are 66% and 34% respectively, indicating relatively higher contribution from biomass burning as compared to other locations in India. This is explained using potential source contribution function (PSCF) and concentration weighted trajectories (CWT) analysis which reveals the potential sources of BC originating from the north-west and eastern parts of IGP and the western part of the Himalayas that are mostly crop residue burning and forest fire regions in India. The annual mean ARF at top-of-atmosphere (TOA), at surface (SUR), and within the atmosphere (ATM) were found to be −14.84 Wm⁻², −43.41 Wm⁻², and +28.57 Wm⁻² respectively. To understand the impact of columnar aerosol burden on ARF, the radiative forcing efficiency (ARFE) was estimated and averaged values were −31.81, −91.63 and 59.82 Wm⁻² τ⁻¹ for TOA, SUR and ATM respectively. The high ARFE within the atmosphere indicates the dominance of absorbing aerosol (BC and dust) over Northwest Himalayas.

This study employs the grain size distributions and the concentrations and isotopic compositions of Sr, Nd, and Pb in the precipitation samples collected from the Laohugou Glacier (LHG) in northeastern Tibetan Plateau (TP) during August 2014–2015 to investigate seasonal variability in the insoluble precipitation particle sources. Fine dust particle (0.57–27 μm) depositions dominated in autumn and winter, whereas both fine and coarse dust particle (27–100 μm) depositions were found in spring and summer. Furthermore, the concentrations of Sr, Nd, and Pb also varied seasonally—the highest and lowest Sr and Nd concentrations were recorded in spring and autumn, respectively, whereas the highest and lowest Pb concentrations were recorded in winter and summer, respectively. The Sr and Nd isotopes revealed that the dust in the winter precipitation originated predominately from the Taklimakan Desert and that in spring originated from the Badain Jaran and Qaidam deserts. The precipitation residues in summer were derived from a complex mixture of dust sources from the Gobi and other large deserts in northwest China. Autumn residues were predominately sourced from local soil near the LHG as well as from the Qaidam Basin and the northern TP surface soil. The Taklimakan, long suspected as a major source of long-range transported dust, was an insignificant contributor to the precipitation over LHG during spring, summer, and autumn. Further, the Pb isotopic ratios indicated a primary impact of anthropogenic pollutants for most part of the year (except spring). Meteorological data and the MODIS AOD model are in good agreement with the results from the analyses of the Sr, Nd, and Pb isotopes for the LHG particle source, and further clarify the source regions. Thus, this study thus provides new evidence on the seasonal variability of the sources of the residual particles in remote glaciers in Central Asia.

Lead (Pb) is an important pollutant and it is of significance to explore the Pb distribution, influencing factors and health risk. Pb concentration and mass load per unit area in 385 street dust samples collected from 19 cities in China were determined during 2011-2013. The results show that the Pb concentration are 68.8, 105.4, 41.7, 49.7, 75.6, 81.7, 131.9, 67.5, 109.3, 164.1, 74.8, 66.4, 99.8, 58.4, 114.0, 59.6, 103.7, 55.4 and 80.4 for Beijing, Chengdu, Daqing, Harbin, Jilin, Jinan, Kunming, Lanzhou, Luoyang, Panzhihua, Qingdao, Yinchuan, Guangzhou, Tangshan, Xi’an, Guangyuan, Nanjing, Taiyuan and Tianjin, respectively. The Pb pollution level of urban street dust varies among cities in the range of 1.72–5.56 times higher than soil background values. The allometric function can fit the change in Pb concentration with particle size well. The medium-sized (38–120 μm) particles contributed 60.2%–80.4% to the Pb load and should be highlighted when selecting street dust management techniques. Influenced by the distribution of Pb ore, the Pb concentration of urban street dust in China shows obvious regional differences, with value in the south 112% higher than that in the north. Among all kinds of mining types, metal-related mining activities discharge a large amount of Pb dust in the process of crushing and smelting, thus contributing most to the Pb load. The Pb load was also affected by transportation. The relationship between Pb load and gross domestic product (GDP) was described with the environmental Kuznets curve (EKC) model, which indicated that the Pb emissions of most cities were still increasing. Finally, the human health risk assessment model with adjusted parameters showed that the Pb risk of all cities was below the threshold. Despite all this, given the EKC law of Pb emission, long-term follow-up assessments are needed.

Whereas the adverse effects of vanadium released from smelting activities on soil microbial ecology have been widely recognized, little is known about spatiotemporal vanadium distribution and microbial community dynamics in typical contaminated sites. This study describes vanadium contents associated with health risk and microbial responses in both topsoil and subsoil during four consecutive seasons around an ongoing-production smelter in Panzhihua, China. Higher levels of vanadium concentration exceeding soil background value in China (82 mg/kg) were found close to the smelter. Vanadium concentrations decreased generally with the increase in distance to the smelter and depth below surface, as soil vanadium pollution is induced mainly by atmospheric deposition of vanadium bearing dust during smelting. Residual fraction was the predominated vanadium form in soils, with pronounced increase in bioavailable vanadium during rainfall period due to frequent drought-rewetting process. Topsoil close to the smelter exhibited significant contamination, inducing high probability of adverse health effects. Spatiotemporal vanadium distribution creates filtering effects on soil microorganisms, promoting metal tolerant genera in topsoil (e.g. Microvirga) and subsoil (e.g. Bacillus, Geobacter), which is the key in maintaining the community structure by promoting cooperative relation with other taxa. Our results reveal spatiotemporal vanadium distribution in soils at site scale with potential health risk and microbial responses, which is helpful in identifying severe contamination and implementing bioremediation.

The present study attempts to explore and compare the seasonal variability in chemical composition and contributions of different sources of fine and coarse fractions of aerosols (PM₂.₅ and PM₁₀) in Delhi, India from January 2013 to December 2016. The annual average concentrations of PM₂.₅ and PM₁₀ were 131 ± 79 μg m⁻³ (range: 17–417 μg m⁻³) and 238 ± 106 μg m⁻³ (range: 34–537 μg m⁻³), respectively. PM₂.₅ and PM₁₀ samples were chemically characterized to assess their chemical components [i.e. organic carbon (OC), elemental carbon (EC), water soluble inorganic ionic components (WSICs) and heavy and trace elements] and then used for estimation of enrichment factors (EFs) and applied positive matrix factorization (PMF5) model to evaluate their prominent sources on seasonal basis in Delhi. PMF identified eight major sources i.e. Secondary nitrate (SN), secondary sulphate (SS), vehicular emissions (VE), biomass burning (BB), soil dust (SD), fossil fuel combustion (FFC), sodium and magnesium salts (SMS) and industrial emissions (IE). Total carbon contributes ∼28% to the total PM₂.₅ concentration and 24% to the total PM₁₀ concentration and followed the similar seasonality pattern. SN and SS followed opposite seasonal pattern, where SN was higher during colder seasons while SS was greater during warm seasons. The seasonal differences in VE contributions were not very striking as it prevails evidently most of year. Emissions from BB is one of the major sources in Delhi with larger contribution during winter and post monsoon seasons due to stable meteorological conditions and aggrandized biomass burning (agriculture residue burning in and around the regions; mainly Punjab and Haryana) and domestic heating during the season. Conditional Bivariate Probability Function (CBPF) plots revealed that the maximum concentrations of PM₂.₅ and PM₁₀ were carried by north westerly winds (north-western Indo Gangetic Plains of India).

Organophosphate esters (OPEs) are widely used as flame retardants, plasticizers and defoamers and their exposure are likely associated with a number of adverse effects in humans. In this study, tris(chloroethyl) phosphate and thirteen OPE metabolites including six hydroxylated OPEs (HO-OPEs) were analyzed in 46 urine samples, collected from 8 provinces located across different regions in China. 1-Hydroxy-2-propyl bis(1-chloro-2-propyl) phosphate (BCIPHIPP) and 2-hydroxyethyl bis(2-butoxyethyl) phosphate (BBOEHEP) were major metabolites of their parent compounds with detection frequencies of 54.3%–89.1%, which were all higher than their corresponding OPE diesters (2.2%–6.5%). The urine-based estimated daily intake (EDI) of OPEs ranged from 0.06 ng/kg·bw for tris(2-butoxyethyl) phosphate (TBOEP) to 273 ng/kg·bw for 2-ethylhexyl phenyl phosphate. Analyzed with concentrations in paired dust samples, dust exposure to OPEs and their diesters may explain 0.28%–23.8% of the urine-based EDI of OPEs and the contribution of dust TBOEP was the highest. Although direct exposure to OPE diesters in dust showed a minor contribution, their intake via food and drinking water may account for a larger portion of urinary OPE metabolites. Overall, the hazard quotients of four OPEs indicated no immediate exposure risk for the investigated Chinese residents but the cumulative and long-term chronic effects involving exposure to other OPEs and OPE diesters are worth further concerns.