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To better understand the effects of COVID-19 on air quality in Taiyuan, hourly in situ measurements of PM2.5(particulate matter with an aerodynamic diameter less than 2.5 mm) and chemical components (water-soluble ions, organic carbon (OC), elemental carbon (EC), and trace elements) were conducted before (P1: 1 January–23 January 2020) and during (P2: 24 January–15 February 2020) the coronavirus disease 2019 (COVID-19) outbreak. The average concentrations of PM2.5 dropped from 122.0 μg/m3 during P1 to 83.3 μg/m3 during P2. Compared with P1, except for fireworks burning–related chemical components (K+, Mg2+, K, Cu, Ba), the concentrations of other chemical components of PM2.5 decreased by14.9–69.8%. Although the large decrease of some emission sources, fireworks burning still resulted in the occurrence of pollution events during P2. The analysis results of positive matrix factorization model suggested that six PM2.5 sources changed significantly before and during the outbreak of the epidemic. The contributions of vehicle emission, industrial process, and dust to PM2.5 decreased from 23.1%, 3.5%, and 4.0% during P1 to 7.7%, 3.4%, and 2.3% during P2, respectively, whereas the contributions of secondary inorganic aerosol, fireworks burning, and coal combustion to PM2.5 increased from 62.0%, 1.8%, and 5.5% to 71.5%, 9.0%, and 6.2%, respectively. The source apportionment results were also affected by air mass transport. The largest reductions of vehicle emission, industrial process, and dust source were distinctly seen for the air masses from northwest. Supplementary Information The online version contains supplementary material available at 10.1007/s11869-021-01082-y.

Polycyclic aromatic hydrocarbons (PAHs) are widespread in the environment and pose a serious threat to the soil ecosystem. In order to better understand the health risks for residents exposed to PAH-contaminated soil, 173 surface soil samples were collected in Shanxi Province, China, to detect the levels of 16 priority PAHs. The spatial distribution patterns of PAHs were explored using interpolation and spatial clustering analysis, and the probable sources of soil PAHs were identified for different land-use covers. The results indicate that the soil Σ16 PAH concentration ranged from 22.12 to 1337.82 ng g−1, with a mean of 224.21 ng g−1. The soils were weakly to moderately contaminated by high molecular weight PAHs (3–5 ring) and the Taiyuan–Linfen Basin was the most polluted areas. In addition, the concentration of soil PAHs on construction land was higher than that on other land-use covers. Key sources of soil PAHs were related to industrial activities dominated by coal burning, coking, and heavy traffic. Based on the exposure risk assessment of PAHs, more than 10% of the area was revealed to be likely to suffer from high carcinogenic risks for children. The study maps the high-risk distribution of soil PAHs in Shanxi Province and provides PAH pollution reduction strategies for policy makers to prevent adverse health risks to residents.

The continued development of the automotive industry has led to a rapid increase in the amount of waste rubber tires, the problem of “black pollution” has become more serious but is often ignored. In this study, the emission characteristics, health risks, and environmental effects of volatile organic compounds (VOCs) from a typical, recycled rubber plant were studied. A total of 15 samples were collected by summa canisters, and 100 VOC species were detected by the GC/MS-FID system. In this study, the total VOCs (TVOCs) concentration ranged from 1000 ± 99 to 19,700 ± 19,000 µg/m3, aromatics and alkanes were the predominant components, and m/p-xylene (14.63 ± 4.07%–48.87 ± 3.20%) could be possibly regarded as a VOCs emission marker. We also found that specific similarities and differences in VOCs emission characteristics in each process were affected by raw materials, production conditions, and process equipment. The assessment of health risks showed that devulcanizing and cooling had both non-carcinogenic and carcinogenic risks, yarding had carcinogenic risks, and open training and refining had potential carcinogenic risks. Moreover, m/p-xylene and benzene were the main non-carcinogenic species, while benzene, ethylbenzene, and carbon tetrachloride were the dominant risk compounds. In the evaluation results of LOH, m/p-xylene (25.26–67.87%) was identified as the most key individual species and should be prioritized for control. In conclusion, the research results will provide the necessary reference to standardize the measurement method of the VOCs source component spectrum and build a localized source component spectrum.

Formaldehyde (HCHO) plays an important role in atmospheric ozone (O

To investigate the trends of chemical characteristics of precipitation in Taiyuan, and factors influencing their variations, a total of 350 precipitation samples were collected from April 2011 to November 2018. The principal water-soluble ions were measured by ion chromatography. PH value (4.34–8.72) was recorded and 14% of all samples were acidic, and was negatively correlated with rainfall amount. The frequency of acid rain decreased year by year, and the acidity was still dominated by SO42−. SO42−, Ca2+, NH4+ and NO3− were the most abundant ions, accounting for 85% of the total concentration, with a significantly decrease rate of 61% during 8 years due to a series of emission reduction measures. The average ratio of neutralizing potential to acidifying potential was 1.37 and experienced an evident increasing trend. This was primarily ascribed to reduced input of SO42− in precipitation. The precipitation acidity was predominantly neutralized by crustal ions Ca2+ and Mg2+. The ionic wet deposition flux was positively correlated to the rainfall amount. Based on Correlation analysis and Positive Matrix Factorization results, four pollution sources of coal combustion and vehicle mixing source (56%), dust (23%), agriculture and industry mixing source (16%) and biomass burning (5%) were identified. Back trajectory showed the air quality of Taiyuan was most significantly affected by the short-distance air mass from the southwest (40%). In order to achieve the SO2 (47%) and NOX (57%) emission reduction targets, we provided a specific energy reform plan in major cities affecting the air quality of Taiyuan before 2030.

Precipitation samples were collected in Taiyuan, China, from January 2013 to December 2015. Thirteen elements were detected by inductively coupled plasma-mass spectrometry (ICP-MS). The total concentration of soluble and insoluble materials averaged 9695.26 μg L−1. Si was the most abundant element, accounting for 94.61% of the total, followed by Al and Fe. The wet deposition flux of the 13 elements was 3065.14 mg m−2·yr−1, with the highest flux detected in the summer and the lowest in the spring. The order of deposition flux was as follows: Si > Al > Fe > Zn > Ba > Cu > Mn > Cr > Sr > Pb > Ni > As > Cd. The elements mainly consisted of insoluble materials and accounted for 56.1–98.5% of the total. Per the enrichment factor (EF) results, Zn, Cu, Pb, As, and Cd were derived mainly from anthropogenic activities, while Al and Fe were derived mainly from crustal dusts. Positive Matrix Factorization (PMF) was used to identify 4 sources of soluble materials in 2015. Results revealed that industrial activities were the leading source, contributing to 50.47% of the total, followed by coal combustion (26.09%), vehicle emissions (13.59%), and dusts (9.85%). Combined with 3 years of back trajectory data, southeasterly air masses (with a proportion of 39%) were the main direction from which the precipitation in Taiyuan originated and had a considerable influence on pH and flux.

Short-chain chlorinated paraffins (SCCPs) are a series of new persistent organic pollutants, posing a risk of significant adverse effects to biota. Increasing attention has been paid to SCCP pollution in China as large amounts of chlorinated paraffin (CP) products containing SCCPs have been produced and used there. However, knowledge of the bioaccumulation of SCCPs in marine organisms from the Pearl River Estuary (PRE), Southern China, is still scarce. In this study, SCCP concentrations were measured in seawater, sediments, and marine organisms from the PRE. SCCP concentrations ranged from 180 to 460 ng/L in seawater, from 180 to 620 ng/g dry weight (dw) in sediments, and from 870 to 36,000 ng/g lipid weight (lw) in marine biota samples. C10–11 SCCPs were the predominant homologues in all the samples, with an average abundance of 68% in seawater, 57% in sediments, and 56–77% in marine organisms. However, chlorine patterns of SCCPs in seawater, sediments, and marine organisms were different. Cl8–10 SCCPs dominated in sediments, whereas Cl5–7 SCCPs were the predominant SCCP homologues in water and most organism species. The logarithm bioaccumulation factors (BAFs) of SCCPs ranged from 1.6 to 3.0, and increased significantly with the increase of Kow values for most marine biota species, indicating that Kow was the major factor controlling the bioaccumulation of SCCPs and that SCCPs with higher lipophilicity were more prone to being bioaccumulated from water. Opposite to that observed for log BAFs, biota-sediment accumulation factors of specific SCCPs (range: 0.01–30) decreased significantly with the increase of Kow values. The biomagnification factor of total SCCPs for oyster–mangrove crab was 2.40, implying the potential biomagnification of SCCPs for benthos in the PRE.

A portable laser sensor for trace ammonia (NH3) is developed based on near-infrared laser absorption spectroscopy. Tunable diode laser absorption spectroscopy in conjunction with wavelength modulation spectroscopy is implemented by a system-on-chip based on field-programmable gate array. A variable temperature multipass cell with a 15 m optical path length is adopted to enhance the absorption path length and avoid the NH3 adsorption. The physical dimension of the sensor is minimized into 43 × 18 × 16 cm3 on the benefit of home-made electronic system and compact optical design. A unique absorption line of NH3 around 1.51 µm covered by a distributed feedback diode laser is selected to reduce the influence from carbon dioxide, vapor and other trace gases. Calibration-free modulation spectroscopy is employed to avoid the random fluctuations due to laser noise and non-absorption transmission losses. The performance of sensor including adsorption of NH3, stability and flow of gas are examined and discussed in detail. For removing the adsorption of NH3, the temperature-dependent curve is obtained by the direct absorption spectroscopy, and it shows that the adsorption is significantly suppressed at (or higher than) 415 K. According to Allan deviation analysis, the minimum detection limit is 0.16 ppm at 184 s, and the rise time and the fall time of system are about 4.5 s and 3.7 s, respectively. The feasibility of the sensor is validated and deployed to monitor the NH3 slip in selective catalytic reduction (SCR) of coke oven flue gas. The work provides a potentially valuable control sensor for SCR.

Ambient carbonyls are critical precursors of ozone (O3) and secondary organic aerosols (SOA). To better understand the pollution characteristics of carbonyls in Taiyuan, field samplings were conducted, and 13 carbonyls were detected in an urban site of Taiyuan for the four seasons. The total concentration of carbonyls in the atmosphere was 19.67 ± 8.56 μg/m3. Formaldehyde (7.70 ± 4.78 μg/m3), acetaldehyde (2.95 ± 1.20 μg/m3) and acetone (5.57 ± 2.41 μg/m3) were the dominant carbonyl compounds, accounting for more than 85% of the total carbonyls. The highest values for formaldehyde and acetone occurred in summer and autumn, respectively, and the lowest occurred in winter. The variations for acetaldehyde were not distinct in the four seasons. Formaldehyde and acetone levels increased obviously in the daytime and decreased at night, while acetaldehyde did not show significant diurnal variations. Higher temperature and stronger sunlight intensity could facilitate the photochemical reaction of volatile organic compounds (VOCs) and enhance the O3 levels in summer. Formaldehyde and acetaldehyde contributed 70–95% of carbonyls’ ozone formation potential (OFP) caused by carbonyls with the highest totals of 268.62 μg/m3 and 38.14 μg/m3, respectively. The highest concentrations of carbonyls from south and southwest winds in summer suggest that the coke industries in the southern Taiyuan Basin should be, firstly, controlled for the alleviation of ozone pollution.

International audience; A palm-sized laser spectrometer has been developed for detecting trace gases based on tunable diode laser absorption spectroscopy (TDLAS) in combination with a novel double-layer toroidal cell. With the benefit of a home-made electronic system and compact optical design, the physical dimension of the sensor is minimized into 24×15×16 cm3. A toroidal absorption cell, with 84 reflections in 2 layers for an effective optical path length of 8.35 m, was used to enhance the absorption signals of gaseous species. A home-made electronic system was designed for implementing distributed feedback (DFB) diode laser controller, analog lock-in amplifier, data acquisition and communication. Calibration-free scanned wavelength modulation spectroscopy was employed to determine the concentration of the gas and reduce the random fluctuations from electronical noise and mechanical vibration. The measurement of CH4 in ambient air was demonstrated using a DFB laser at 1.653 μm. The rise time and fall time for renewing the gas mixture are approximately 16 s and 14 s, respectively. Vibration and temperature tests have been carried out for verifying the performance of the spectrometer, and standard deviations of 0.38 ppm and 0.11 ppm for 20 ppm CH4 at different vibration frequencies and temperatures, respectively, have been determined. According to the Allan deviation analysis, the minimum detection limit for CH4 can reach 22 ppb at an integration time of 57.8 s. Continuous measurement of atmospheric CH4 for two days validated the feasibility and robustness of our laser spectrometer, providing a promising laser spectral sensor for deploying in unmanned aerial vehicles or mobile robots.

The quality of urban soil is closely related to the safety of public places and the guarantee of food quality. This study investigated the level, distribution, source, and carcinogenic risk of 16 U.S. EPA (Environmental Protection Agency) priority polycyclic aromatic hydrocarbons (PAHs) in urban, agricultural, and montane soil in Taiyuan. The &sum, 16PAHs level varied from 104.78 to 6594.63 ng g&minus, 1 with a mean of 922.93 ng g&minus, 1, and 47.73% of the soil samples were severely contaminated, with a concentration higher than 600 ng g&minus, 1. PAHs with higher molecular weight (&ge, 4 rings) were dominant in PAHs profiles accounting for 80.92%. In the spatial distribution of PAHs, hotspots of &sum, 16 PAHs were observed near the industries, indicating pollutants emitted by the industries directly affect the surrounding soil quality. The sources identified by positive matrix factorization (PMF) indicated: coal combustion (40.77%), vehicle exhausts (32.94%), biomass combustion (14.89%), and coking source (11.40%). Coal-related sources (coal and coking sources) were the major contributors (52.17%) to PAHs and carcinogenic risk (46.48%) assessed by BaP toxic equivalent concentration in total soils. Therefore, the extensive usage of coal was the leading factor for PAH pollution and health risk in Taiyuan soil.

The mixed chelators (MC) of N, N-bis(carboxymethyl) glutamic acid (GLDA) and citric acid (CA), which were biodegradable chelating ligand, were employed to remove heavy metals from sewage sludge. The extraction of Cd, Cu, Zn, Mn, and Cr from sludge was studied under different experimental conditions. Results showed that the removal efficiencies of heavy metals from both sludges were the highest with MC of GLDA and CA at the molar ratio of 1:5. For the sludge of plant A, the extraction efficiencies increased with increasing contact time, but only slowly increase was observed after 24 h. However, for the sludge of plant B, the removal efficiencies were significantly decreased after 16 h, and sharply decreased after 24 h. The removal efficiencies of heavy metals decreased with the increase of the solution pH, while they increased with the increase of the solution concentration. For the sludge of plant A, single washing with 200 mmol·L

International audience; We developed a type of toroidal multi-pass cell with multi-layer patterns based on the off-axis model. The effective path length of the original toroidal multi-pass cell is extended several roundtrips in comparison with the single-layer pattern, since the inner surface of the toroidal multi-pass cell is more efficiently utilized. The light pattern has been achieved by using the simple ring surface, which is easy to fabricate. The exact analytical equations for the design of the toroidal multi-pass cell were derived based on analytical vector calculations. A series of numerical ray tracing simulations is presented, and the maximum theoretical optical path length that can be reached is 30 m with a setup of 5 cm column radius. Furthermore, two practical spot patterns are demonstrated with a path length of 8.3 m for a two-layer pattern and 10 m for a three-layer pattern, with respective effective volumes of 63 mL and 94 mL. Furthermore, the fringe effect is substantially reduced to less than 0.5% by the usage of our designed mask.

Plant-residue derived biochars from walnut shell, corn cob, corn straw, and rice straw obtained at three heat treatment temperatures (HTTs) (250 °C, 400 °C, and 600 °C) were applied in an incubation experiment to investigate how feedstocks, HTTs, and biochar properties affect the quantity of microorganisms, microbial community shift, enzyme activity, and biodegradation of polycyclic aromatic hydrocarbons (PAHs) in an aged contaminated soil. The microbial quantities (bacteria and fungi) and enzyme activities (catechol 2,3-dioxygenase and ligninolytic enzymes) generally decreased with the increase in HTTs. Microbial quantities had significantly positive correlations with the aliphatic carbon (C) (p

This study investigated the levels of persistent toxic substances, such as 16 polycyclic aromatic hydrocarbons (Σ16PAHs) and heavy metals (Cu, As, Cd, Zn, Pb, Ni, Mo, and Cr) in biochars produced from crop residues (walnut shell, corn cob, corn straw, rice straw, and rice husk) at different heat treatment temperatures (HTTs, 250, 400, and 600 °C). The levels of Σ16PAHs in different biochars were 0.47–7.11 mg kg−1, with naphthalene and phenanthrene contributing the most. The Σ16PAHs had the positive correlations with H/C and (O + N)/C, but had negative correlations with biochar surface areas. This finding indicates the increasing hydrophobic π-π interactions between the PAHs and the aromatic sheets of biochars and even the trapping of PAHs within the micropores with the increase of HTTs. The levels of heavy metals in rice residue-derived biochars were significantly higher than those in other biochars. The heavy metals had positive correlations with ash contents in the biochars, indicating the enrichment of heavy metals in the ash. The potential ecological risks of PAHs and heavy metals (dosage: 1%, w/w; frequency: 1) were minimal according to the risk quotient of negligible concentrations (RQNCs: 2.50–47.40, <

International audience; Nitric oxide (NO) is an important product released by cigarette burning with significantly negative effects to both environment and human health, but it is hard to be measured in-situ in the process of burning. In this paper, we report a tunable diode laser absorption spectroscopy (TDLAS) set-up using a quantum cascade laser emitting at 5.24 m to continuously determine the emitted NO mass in cigarette smoke during burning. Wavelength modulation spectroscopy was applied to improve the detection sensitivity and robustness of the measurement system. A simple single-pass gas cell with a volume of 28 cm3 was used to record the absorption spectra, and then the mass of NO was derived based on the measured line strength. Allan variance analysis demonstrated that the limit of detection of system reached 28 ppb over 180 s integration time. Due to the low effective volume, the rise time and the fall time were rapid with 3 s and 6 s, respectively. An adaptive Kalman filter was used to reduce the noise on the concentration measurement. As a result, the measurement precision is improved by a factor of 4.5. For accurate determination the total NO mass, the emissions of mainstream (MS) and sidestream (SS) of a burning cigarette were individually measured at the same continuous flow rate. The recorded results of three types of cigarettes revealed that the NO mass emitted in the MS is correlated with the sampling flow rate, while the NO mass emitted by the same cigarette in the SS is hardly influenced by at different smoke flow rates. And different cigarette types with identical physical dimensions emit approximately equivalent mass of NO. This work provides a promising method for determining the mass of emitted NO and other compositions of cigarettes smoke.

Little is known regarding how biochars' feedstock and pyrolysis temperature affect soil function and plant growth. To address this gap in knowledge, 12 biochars (walnut shells, corn cobs, corn straws, and rice straws were separately pyrolyzed at 250, 400, and 600 °C for 4 h) were applied to soil from an indigenous coking site with application rate of 2.5% (w/w) in a pot experiment to determine the impact of biochar types on macro-nutrients (total and available N, P, and K) and ryegrass growth in the soil from an indigenous coking site. Generally, the total N, P, and K in the soil was not significantly different from that of the control group. However, biochars decreased the available N from 21.76 mg·kg − 1 for the control to 14.96 mg·kg − 1 . Corn straw and rice straw biochars increased the available P from 2.14 mg·kg − 1 for the control to 28.35 mg·kg − 1 , specifically at higher pyrolysis temperature, while walnut shell and corn cob biochars had little influence on it regardless of pyrolysis temperature. Biochars increased the available K from 173.58 mg·kg − 1 for the control to 355.64 mg·kg − 1 , varying as their feedstocks of corn cob > rice straw > corn straw > walnut shell and increasing with the increase of pyrolysis temperature. Correlation analysis suggests that it is responsible for the competition of soluble cations from biochars with K for adsorption sites on the soil surface. Biochars increased the ryegrass biomass from 0.07 g·pot − 1 for the control to 0.16 g·pot − 1 , with the generally most effective stimulation by biochars produced at 400 °C. Ryegrass biomass had obviously positive correlation with available K, indicating its essential role in the growth of ryegrass in the studied soil.

To better understand the causes of visibility degradation in Taiyuan, the concentrations of PM1.5 and main chemical compositions were analyzed during the period from July 28, 2014 to April 26, 2015. The average concentration of PM1.5 during the sampling period was 107.6 ± 51.0 μg/m3. The concentrations of secondary inorganic water-soluble ions (SIA, the sum of SO42−, NO3− and NH4+), OC and EC were 31.0 μg/m3, 14.6 μg/m3 and 6.0 μg/m3, accounting for 28.8%, 13.5% and 5.6% of PM1.5, respectively. Light extinction coefficients (bext) were estimated by the revised US Interagency Monitoring of Protected Visual Environments (IMPROVE) equation. (NH4)2SO4 (48.7%) was the largest contributor to bext in summer, while the contribution of organic matter (OM) to bext was the highest in spring (25.0%) and winter (42.0%). Compared with non-haze days in summer and winter, the contributions of (NH4)2SO4 and NH4NO3 to bext during haze days increased, while the contributions of OM, EC, fine soil and coarse matter (PM1.5-10) decreased. Air masses from the southern areas had the largest bext and contribution of (NH4)2SO4 in summer and winter. The results of source apportionment by positive matrix factorization model found that secondary sulfate, secondary nitrate, coal combustion, vehicle emission, fugitive dust, biomass burning were the main sources to bext in Taiyuan. Secondary sulfate (81.7%) and coal combustion (43.1%) were the largest contributors to the bext in summer and winter during haze days, respectively. The results of our study could improve the understanding of the major sources that affect visibility degradation in Taiyuan.

Polyurethane/epoxy resin modified asphalt (PEA) has substantial potential in functioning as adhesive layer material for steel-ultra high performance concrete (UHPC) composite bridge deck pavements. In this research, the curing process of PEA was analyzed by Fourier transform infrared spectroscopy (FTIR) and fluorescence microscopy (FM) tests. Furthermore, mechanical and engineering performances of PEA were evaluated and further compared with those of styrene-butadiene-styrene (SBS) modified asphalt by viscosity test, tensile test, pull-out test, and dynamic shear rheometer (DSR) test. Results indicate that during the curing process of PEA, the polyurethane/epoxy resin undergoes a reaction with curing agent to form an interpenetrating polymer network (IPN) structure with a phase transition of polyurethane/epoxy resin from a dispersed phase to a continuous phase. The viscosity of PEA is affected by the asphalt content and temperature. PEA possesses excellent mechanical properties due to the formation of IPN structure and the toughening effect of asphalt. The high-temperature stability of PEA is far better than that of SBS modified asphalt. Additionally, the low-temperature cracking resistance and waterproof performances of PEA can meet the requirements of the adhesive layer well.

Regional ozone pollution has become one of the most challenging environmental problems in China. In July 2019, hourly real-time monitoring of ozone (O3) and nitrogen oxides (NOx) and 3-hour off-line measurement of volatile organic compounds (VOCs) during a 10-day intensive campaign were conducted at four sites in Taiyuan, Shanxi Province, China. The average mixing ratio of total VOCs (including alkanes, alkenes, aromatics and acetylene) was 14.8 ± 2.8 ppbv and the dominant VOCs species to O3 formation were alkenes in Taiyuan. According to China Ambient Air Quality Standard Grade II (hourly averaged mixing ratio of 103 ppbv), the studied periods were divided into O3 attainment periods (EP1) and O3 pollution periods (EP2). A continuous O3 pollution event was captured during 12–15 July, with the maximum hourly O3 mixing ratio of 131.7 ppbv. Higher temperature, lower relative humidity, weaker winds and local photochemical reaction were conducive to O3 pollution during EP2. The analysis of VOCs/NOx ratio indicated that the formation of O3 was co-controlled by both VOCs and NOx during the period of 12:00–18:00 LT (high value period of O3), and it was controlled by VOCs during the remaining period. The abundances, compositions of typical VOCs and VOCs/NOx ratio showed clear spatial and temporal variations. Six major sources of VOCs were identified by positive matrix factorization, including coal and biomass combustion (33%), coking sources (28%), vehicular emissions (14%), solvent usage (10%), industrial processes (8%) and biological sources (7%). Backward trajectory analysis found that higher concentration of O3 in air masses from local (70%) and southern areas (22.5%) during EP2. Local (32%) and southern (30%) coking sources were the main contributors of ozone formation potential (OFP) during EP2.

Atmospheric dry deposition is a major pathway of pollutants removal from the atmosphere to the water and soil ecosystem. Polycyclic aromatic hydrocarbons (PAHs) in Taiyuan, China, are one class of the most hazardous air pollutants due to the high emission intensity from coal consumption. To better understand the PAHs removing from the atmosphere, 16 USEPA priority PAHs (except for naphthalene) in the particle dry deposition samples were detected from August 2013 to November 2014 at an urban site in Taiyuan. Dry deposition fluxes of particles were estimated as 157.44–358.17 mg/(m 2 ·d), with the highest value in spring and lowest in autumn. Particle dry deposition fluxes of ∑15-PAHs ranged from 2436.20 to 14,967.36 ng/(m 2 ·d), and was the highest in winter and lowest in summer. Higher PAHs particle dry deposition fluxes were related to higher PAHs emission, lower air temperature, less precipitation as well as wind speed. Overall dry deposition velocities of 15-PAHs were 0.056 ± 0.027 cm/s in winter and 0.42 ± 0.050 cm/s in summer, respectively, and high molecular weight PAHs showed low dry deposition velocities. Positive matrix factorization model's results indicated that coking, vehicle exhaust, coal combustion were the primary PAHs sources in particle dry deposition samples, accounting for 18.64%, 26.54% and 54.82% of total PAHs, respectively. The toxic equivalent concentrations (BaPeq) of ∑15-PAHs in particle dry deposition samples was in the range of 0.69–2.94 μg/g, which might be a good explanation to high soil PAHs concentrations reported in Shanxi province, China. Furthermore, this work could prove the significance of coal combustion, and related pollution control works are needed to conduct to alleviate the PAHs pollution situation.

Coking is regarded as a major source of atmospheric polycyclic aromatic hydrocarbons (PAHs), but few researches have been conducted on the emission characteristics of PAHs from coke production. In this study, emissions of size-segregated particulate matter (PM) and particle-bound PAHs emitted from charging of coal (CC) and pushing of coke (PC) in four typical coke plants were determined. The emission factors on average, sums of CC and PC, were 4.65 mg/kg, 5.96 mg/kg, 19.18 μg/kg and 20.69 μg/kg of coal charged for PM 2.1 (≤ 2.1 μm), PM, PAHs in PM 2.1 and total-PAHs, respectively. PM and PAHs emission from plants using stamp charging were significantly more than those using top charging. The profile of PAHs in PM with size ≤ 1.4 μm (PM 1.4 ) emitted from CC process were similar with that from PC, however, it revealed obviously different tendency for PAHs in PM with size > 1.4 μm, indicating the different formation mechanism for coarse particles emitted from CC and PC. Size distributions of PM and PAHs indicated that they were primarily connected with PM 1.4 , and the contributions of PM 1.4 to PM and PAHs emitted from the plants using stamp charging were higher than those using top charging. Some improved technology in air-pollution control devices should be considered in coke production in future based on the considerable impacts of PM 1.4 and PAHs on human health and ambient air quality.

Atmospheric transport of black carbon (BC) from surrounding areas has been shown to impact the Tibetan environment, and clarifying the geographical source and receptor regions is crucial for providing guidance for mitigation actions. In this study, 10 trace volatile organic compounds (VOCs) sampled across Tibet are chosen as proxies to diagnose source regions and related transport of pollutants to Tibet. The levels of these VOCs in Tibet are higher than those in the Arctic and Antarctic regions but much lower than those observed at many remote and background sites in Asia. The highest VOC level is observed in the eastern region, followed by the southern region and the northern region. A positive matrix factorization (PMF) model found that three factors—industry, biomass burning, and traffic—present different spatial distributions, which indicates that different zones of Tibet are influenced by different VOC sources. The average age of the air masses in the northern and eastern regions is estimated to be 3.5 and 2.8 days using the ratio of toluene to benzene, respectively, which indicates the foreign transport of VOC species to those regions. Back-trajectory analyses show that the Afghanistan-Pakistan-Tajikistan region, Indo-Gangetic Plain (IGP), and Meghalaya-Myanmar region could transport industrial VOCs to different zones of Tibet from west to east. The agricultural bases in northern India could transport biomass burning-related VOCs to the middle-northern and eastern zones of Tibet. High traffic along the unique national roads in Tibet is associated with emissions from local sources and neighboring areas. Our study proposes international joint-control efforts and targeted actions to mitigate the climatic changes and effects associated with VOCs in Tibet, which is a climate sensitive region and an important source of global water.

Atmospheric polycyclic aromatic hydrocarbons (PAHs) were analyzed in the gas phase and total suspended particulate (TSP) from summer 2014 to spring 2015 in Taiyuan, northern China. Taiyuan is an area with some of the highest atmospheric PAH levels in the world, and the total PAHs was highest in winter, followed by autumn, spring and summer. Low air temperature and a southern wind with low speed often led to higher PAH levels in Taiyuan. Although less than a half fraction, the benzo[a]pyrene equivalent concentration (BEQ) of particulate PAHs was almost equal to that of the total PAHs. Four sources, coal combustion, vehicle emissions, coke processing and biomass burning, were determined by positive matrix factorization (PMF), with contributions of 41.36%, 24.74%, 19.71% and 14.18% to the total PAHs in Taiyuan, respectively. Compared with the total PAHs, the particulate PAH solution underestimated the contribution of the coke processing, especially in winter, and overestimated vehicle emissions. The coke processing had a greater contribution to atmospheric PAHs with a southern wind at low speeds in winter in Taiyuan. Ultimately, the coke plants distributed in the Taiyuan-Linfen-Yuncheng basin should receive greater attention for air quality improvement in Taiyuan.

Studied in this paper is the design of a command filtered backstepping sliding mode controller for the hose whipping phenomenon in aerial refueling. Firstly, a dynamic model of the variable-length hose–drogue assembly with the restoring force due to bending previously built by the authors is introduced as a control plant. According to the kinematics, the hose length control is transformed to the angular control of the permanent magnet synchronous motor to keep the hose tension stable and suppress the hose whipping. Then, an active control strategy based on command filtered backstepping sliding mode angular control of the permanent magnet synchronous motor is proposed. To maximize the output torque, the space vector modulation method is adopted. Considering the strict-feedback configuration of the angular velocity subsystem, command filtered backstepping is used to eliminate the analytic computation of high order command derivatives required in the previous control system design. In the current voltage subsystem, exponential sliding mode reaching laws of d-axis and q-axis current errors are applied to enhance convergence speed, control accuracy, and robustness. Results show that the control system is simplified substantially and the requirement on the number of sensors is also relaxed. Finally, the superiority of the control laws is analyzed by simulations.

Soil washing with chelators is a viable treatment alternative for remediating multi-contaminated soils. The aim of this study was to investigate the removal efficiencies of Cd, Zn, Pb, and Cu in alkaline and acid multi-metal-contaminated soils by washing with the mixed chelators (MC). The batch experiments were carried out to evaluate the removal efficiencies of heavy metals in contaminated soils by the MC with different molar ratios of EDTA, GLDA, and citric acid, and evaluated the washing factors, including contact time, pH, MC concentration, and single and multiple washings at the same MC dose, on the removal efficiencies. Results showed that the removal efficiencies for Cd, Zn, Pb, and Cu by the MC (the molar ratio of EDTA, GLDA, and citric acid was 1:1:3) were as much as those of the only EDTA washing from both soil at the same application dose of total chelators; moreover, the application dose of EDTA decreased by 80%. For the alkaline-contaminated soil, the removal efficiencies of Cd, Zn, Pb, and Cu decreased with the increasing of the solution pH, which was opposite to acid-contaminated soil. This was attributed to that the metal-ligand complex could be obviously re-adsorbed on the soil surface sites, particularly in low pH values. The removal efficiencies of Cd, Zn, Pb, and Cu depended on MC concentration. A higher MC concentration led to a more effective removal of Cd, Zn, Pb, and Cu in alkaline-contaminated soil; however, their changes were slightly increased in acid-contaminated soil. At the same dose of MC, single washing with higher MC concentration might be favorable to remove heavy metals, moreover, with much less wastewater generation. The MC (the molar ratio of EDTA, GLDA, and citric acid was 1:1:3) may be a useful, environmentally friendly, and cost-effective chelators to remediate heavily multi-metal-contaminated soil.

Long-range transport followed by deposition of black carbon on glaciers of Tibet is one of the key issues of climate research as it induces changes on radiative forcing and subsequently impacting the melting of glaciers. The transport mechanism, however, is not well understood. In this study, we use short-lived reactive aromatics as proxies to diagnose transport of pollutants to Tibet. In situ observations of short-lived reactive aromatics across the Tibetan Plateau are analyzed using a regional chemistry and transport model. The model performance using the current emission inventories over the region is poor due to problems in the inventories and model transport. Top-down emissions constrained by satellite observations of glyoxal are a factor of 2–6 higher than the a priori emissions over the industrialized Indo-Gangetic Plain. Using the top-down emissions, agreement between model simulations and surface observations of aromatics improves. We find enhancements of reactive aromatics over Tibet by a factor of 6 on average due to rapid transport from India and nearby regions during the presence of a high-altitude cut-off low system. Our results suggest that the cut-off low system is a major pathway for long-range transport of pollutants such as black carbon. The modeling analysis reveals that even the state-of-the-science high-resolution reanalysis cannot simulate this cut-off low system accurately, which probably explains in part the underestimation of black carbon deposition over Tibet in previous modeling studies. Another model deficiency of underestimating pollution transport from the south is due to the complexity of terrain, leading to enhanced transport. It is therefore challenging for coarse-resolution global climate models to properly represent the effects of long-range transport of pollutants on the Tibetan environment and the subsequent consequence for regional climate forcing.

PM 2.5 samples were collected in urban area in Taiyuan for four seasons from August 2009 to April 2010. The Water-soluble inorganic ions (WSI, including F − , Cl − , NO 3 − , SO 4 2 − , Na + , NH 4 + , K + , Mg 2 + , and Ca 2 + ) were analyzed by ion chromatography. The daily PM 2.5 levels in the field samples varied from 49.90 to 477.93 μg/m 3 with the mean of 209.54 μg/m 3 , which all largely exceeded the PM 2.5 24-hour limitation value of 35 μg/m 3 in Environmental Protection Administration of United States and 75 μg/m 3 in Ministry of Environmental Protection of China. The WSI average concentration was 68.86 μg/m 3 and accounted for about 32.86% of PM 2.5 . As the most abundant anion and cation, SO 4 2 − and NH 4 + were 43.53 and 14.78 percent of WSI, respectively. PM 2.5 in Taiyuan was acidic by the micro-equivalents concentration methods but nearly neutral in autumn, and the chemical forms of WSI were mainly NH 4 HSO 4 , (NH 4 ) 2 SO 4 and NH 4 NO 3 . PM 2.5 and WSI levels showed obvious seasonal variation and were the highest in winter in all samples. PM 2.5 , SO 4 2 − , and some coal-related ions such as NH 4 + and Cl − were higher in winter than other seasons, which mainly attributed to more coal combustion for power and indoor heating supply. The ratio analysis showed that Mg 2 + and Ca 2 + were not only from soil dust, but also from coal combustion and industry emission. Biomass burning such as the cornstalk and tree branches led to the highest K + emission in autumn and summer. Wind had a regular influence on the PM 2.5 and WSI, and would transport the soil dust mainly from the northwest and also lead to re-suspension of dust in the air when the wind speed was high. Furthermore, the dustpan topography easily helped the pollutants to concentrate in Taiyuan city, and some coal coking industries might contribute to high PM 2.5 and WSI in Taiyuan.

Because of mountain cold-trapping, the soil in the Tibetan Plateau may be an important global sink of organochlorine pesticides (OCPs). However, there are limited data on OCPs in the soils of the Tibetan Plateau. In addition, the atmospheric transport and deposition mechanisms of OCPs also need to be further studied. In this study, the sampling area covered most regions of the Tibetan Plateau. The detection frequencies of ΣChlordane (sum of trans-chlordane, cis-chlordane and oxychlordane), HCB, ΣNonachlor (sum of trans- and cis-nonachlor), DDTs, ΣEndo (sum of endosulfan-I, endosulfan-II and endosulfate), aldrin, HCHs, ΣHeptachlor (sum of heptachlor and heptachlor epoxide), mirex and dieldrin were 100%, 98.3%, 96.6%, 94.8%, 89.7%, 87.9%, 62.1%, 55.2%, 32.8% and 6.9%, respectively. DDTs (with arithmetic mean values of 1050ngkg-1 dw) and HCHs (393ngkg-1) were the principal OCPs in cultivated soils, whereas ΣEndo (192ngkg-1) and ΣChlordane (152ngkg-1) were the principal OCPs in non-cultivated soils. Local use of DDTs, dicofol and HCHs may be an important source of OCP accumulation in the soil of the Tibetan Plateau. Aldrin and endosulfan are considered to be good indicators for studying atmospheric transport and deposition of OCPs from South Asia and Southeast Asia. Two zones with high OCP levels were found in the southeast and northwest of the Tibetan Plateau. The zones have dissimilar pollution sources of OCPs and are influenced by different factors that affect their precipitation scavenging efficiency. The amount of precipitation was the dominant factor in the southeast, whereas large differences in temperature and wind speed were the dominant factors in the northwest.

Soil washing is an effective technology for the remediation of soils contaminated with various metals. However, the bioavailability of residual metals in soils and soil properties can be changed during the washing processes. In this study, we used four amendments to revitalize mixed chelator (MC)–washed soils (WS). These amendments included zeolite, CaCO3, biochar, and chicken manure. Results showed that inorganic amendments reduced the available Cd and Zn concentrations, while organic amendments, particularly chicken manure, reduced the Pb bioavailability in WS. The combination of 0.2% CaCO3 and 2% chicken manure amendments reduced the Cd, Pb, and Zn bioavailability by 45.8%, 77.8%, and 15.0% compared with the control treatment, respectively. The inorganic amendments should increase the seed germination rate of Chinese cabbage (Brassica rapa L.). However, the shoot growth decreased significantly. The combination of amendments cannot increase the seed germination but can significantly increase the shoot growth of Chinese cabbage compared with the control. The combination of amendments enhanced the fertility of WS, particularly available P and exchangeable K, which may improve plant growth. These results suggested that the combination of amendments, especially CaCO3 (0.2%) and chicken manure (2%), can be used to revitalize MC-WS.

Taiyuan city in Shanxi province, China has been one of the top heavily polluted cities in the world for a long time with large industrial emissions and high disease burden. Many pollution control strategies have been implemented forcefully by the government in recent years in Taiyuan. To better understand the effect of the strategies and related influence factors, we studied polycyclic aromatic hydrocarbons (PAHs) in fine particulate matter (PM 2.5 ) during heating seasons in Taiyuan from 2009 to 2013. The results showed that the concentrations of PM 2.5 (70.7–477.9 μg/m 3 ) and related total PAHs (T-PAHs, 128.7–1840.2 ng/m 3 ) far exceeded the air quality standards issued by the Ministry of Environmental Protection of China (MEP) and were higher than those in many domestic and foreign cities in spite of the pollution control. Source apportionment by the diagnostic ratio analysis and PMF model found that coal consumption contributed the most (52.1%) to the total PM 2.5 -bound PAHs followed by the coking industry (27.3%) and traffic exhausts (20.6%). Significant decreases in PM 2.5 and PAHs levels were found in 2013, which was probably due to the large abatement of residential coal consumption and favorable meteorological factors. Being located in the north of Taiyuan basin, the pollution in Taiyuan could be aggravated by the regional transport of coal combustion- and coking-related pollutants from other industrial development zones in the south-western basin as found by the analysis of meteorological influence and back trajectory. Although the PAHs were the lowest in 2013, the BaP eq or ILCR were the highest in that year. This should be related to the increasing vehicle numbers in Taiyuan, because vehicle exhaust tends to enrich in higher molecular weight and more toxic PAHs. Our results provided useful guidance for solving the air pollution problem for cities in a semi- or total-closed basin with coal as the major energy source such as Taiyuan.

Concentrations of gaseous elemental mercury (GEM) were continuously monitored from May 2011 to May 2012 at the Wuzhishan State Atmosphere Background Monitoring Station (109°29′30.2″ E, 18°50′11.0″ N) located in Hainan Island. This station is an ideal site for monitoring long-range transport of atmospheric pollutants from mainland China and Southeast Asia to South China Sea. Annual average GEM concentration was 1.58 ± 0.71 ng m−3 during the monitoring period, which was close to background values in the Northern Hemisphere. GEM concentrations showed a clear seasonal variation with relatively higher levels in autumn (1.86 ± 0.55 ng m−3) and winter (1.80 ± 0.62 ng m−3) and lower levels in spring (1.16 ± 0.45 ng m−3) and summer (1.43 ± 0.46 ng m−3). Long-range atmospheric transport dominated by monsoons was a dominant factor influencing the seasonal variations of GEM. The GEM diel trends were related to the wind speed and long-range atmospheric mercury transport. We observed 30 pollution episodes throughout the monitoring period. The analysis of wind direction and backward trajectory suggested that elevated GEM concentrations at the monitoring site were primarily related to the outflows of atmospheric Hg from mainland China and the Indochina peninsula. The △GEM/△CO values also suggested that GEM was significantly affected by the long-range transport from the anthropogenic sources and biomass burning in Asia and Indochina peninsula.