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To achieve near-continuous vertical observations of volatile organic compounds (VOCs) in the planetary boundary layer (PBL), multi-channel whole-air sampling equipment onboard an unmanned aerial vehicle (UAV) platform was developed in this study. The equipment consists of a multi-position solenoid valve and specially designed lightweight quartz sampling canisters. The canisters have little adsorption loss of VOCs and good inter-canister reproducibility. The 7 d recovery test shows that most VOC species (97 %) had a 1-week decay within 20 %. Online instruments for measuring O3, NO2, CO, SO2, and meteorological parameters are also integrated into the UAV platform. During one take-off and landing, the UAV platform can reach 800 m above the ground within 40 min and take whole-air samples at six heights. Vertical profiles of VOCs and trace gases during the evolution of the PBL in south-western China are successfully obtained by deploying the newly developed UAV system.

To achieve near-continuous vertical observations of volatile organic compounds (VOCs) in the planetary boundary layer (PBL), multi-channel whole-air sampling equipment onboard an unmanned aerial vehicle (UAV) platform was developed in this study. The equipment consists of a multi-position solenoid valve and specially designed lightweight quartz sampling canisters. The canisters have little adsorption loss of VOCs and good inter-canister reproducibility. The 7-day recovery test shows that most VOC species (97 %) had a one-week decay within 20 %. Online instruments for measuring O3, NO2, CO, SO2, and meteorological parameters are also integrated into the UAV platform. During one take-off and landing, the UAV platform can reach 800 m above the ground within 40 min and take whole-air samples at six heights. Vertical profiles of VOCs and trace gases during the evolution of the PBL in southwest China are successfully obtained by deploying the newly developed UAV system.

The long-term and high temporal resolution measurement of ambient volatile organic compounds (VOCs) was continuously performed in urban Beijing in 2016. Historical VOC data were compiled and compared with our results. A positive matrix factorization (PMF) model was used to determine potential emission sources. The backward trajectories and the concentration, ozone formation potential (OFP), and secondary organic aerosol potential (SOAP) of VOCs in the air masses from different regions were used to estimate the VOC chemical behaviour and transport-direction contributions. A health assessment, including the carcinogenic risk and non-carcinogenic risk of specific hazardous VOC species, was performed, while the point estimate approach was used for risk apportionment based on emission sources. In this study, the average (±standard deviation, Std) concentration of total observed VOCs (TVOCs) was 101.5 ± 65.2 μg/m3, ranging from 21.4 to 439.1 μg/m3. The VOC concentration in Beijing had decreased but was still higher than that in other Chinese cities according to compiled reported VOC data. Combustion-related sources were the primary sources of VOC pollution in urban Beijing. VOC contributions were increasingly coming from the northwestern regions instead of solely from regions to the south of Beijing according to the VOC concentration, OFP, and SOAP data. A potential health risk from VOCs should be considered for residents living in Beijing. The results of this study are expected to provide basic data for efficient VOC emission management and public health protection in Beijing.

Nitrate, sulfate and ammonium (NSA) are the main secondary inorganic aerosols of PM2.5 and play an important role in air pollution. In this study, a 3-year observational experiment was conducted from 1 January 2015 to 31 December 2017, in Chengdu, southwest China. NSA pollution characteristics, chemical conversion generation, emission reduction control sensitivity and pollutant regional transport characteristics were analyzed. NSA are the most important chemical compositions of particles with aerodynamic equivalent diameter ≤2.5 µm in ambient air ( PM2.5 ), and the contribution of nitrate to the accumulation of PM2.5 concentration is greater than that of sulfate and ammonium. NSA also have obvious characteristics of annual, monthly, seasonal, diurnal and weekly variations. Through observation data and model simulation, it was also found that the existence of an aerosol aqueous environment plays an important role in the formation and existence of NSA. Sensitivity analysis between NSA found that controlling NO 3 - and SO 4 2 - plays an important role in reducing the contribution of NSA to PM2.5 , which also implies that the current control of NOx and SO2 is important for improving air pollution. Combined with meteorological conditions and potential source contribution function (PSCF) analysis, local emissions and regional emissions of pollutants are found to have important impacts on Chengdu's atmospheric environment. This research result not only provides an assessment of the current atmospheric emission reduction effect but also provides an important reference for atmospheric pollution control.

Observations of volatile organic compounds (VOCs) are a prerequisite for evaluating the effectiveness of government efforts targeting VOC pollution. Here, based on the one-year online VOC measurement in 2018 in Beijing, systematic analyses and model simulation were conducted to illuminate VOC characteristics, emission sources, regional hotspots and behaviours in response to O

Nitrate, sulfate and ammonium (NSA) are the main secondary inorganic aerosols of PM2.5 and play an important role in the process of air pollution. However, few studies have analysed the variation characteristics of NSA in PM2.5 and the effects of control measures through long-term observations. In this study, a long-term observational experiment was conducted from January 1, 2015 to December 31, 2017 in Chengdu, southwest China. NSA pollution characteristics, chemical conversion generation, emission reduction control sensitivity analysis and pollutant regional transport characteristics were analysed. The concentrations of sulfate and ammonium in PM2.5 have been well reduced, but the effect of reducing nitrate was not obvious. Seasonal and diurnal variations have obvious characteristics, winter still has a high NSA concentration and emission intensity, and the concentration during the day was higher than that at night. Although the workday concentration was slightly higher than the weekend concentration, the difference was nonsignificant. The chemical conversion characteristics of NSA formation were comprehensively analysed, and the aqueous phase oxidation process plays an important role in the conversion of NOx, SO2 and NH3 to NSA. The ammonia-rich environment became increasingly obvious in the atmosphere of Chengdu. Under these conditions, the sensitivity of NSA concentration variation was analyses using the ISORROPIA-II thermodynamic model, and the results show that by reducing NOx and SO2 emissions, not only can reduce the nitrate and sulfate in PM2.5, but also help reduce the formation of ammonium nitrate and ammonium sulfate to reduce ammonium. The results also show that while carrying out NSA emission reduction, it is also possible to generate potential risks of changes in aerosol pH. Combined with meteorological conditions and a potential source contribution function (PSCF) analysis, local emissions and regional emissions of pollutants are found to have important impacts on Chengdu's atmospheric environment. This research result not only provides an assessment of the current atmospheric emission reduction effect but also provides an important reference for determining methods to further reduce the NSA concentration in atmospheric PM2.5.

Observations of volatile organic compounds (VOCs) are a prerequisite for evaluating the effectiveness of government efforts targeting VOC pollution. Here, based on the one-year online VOC measurement in 2018 in Beijing, systematic analyses and model simulation were conducted to illuminate VOC characteristics, emission sources, regional hotspots and behaviours in response to O3 formation. The observed mean VOC concentration in 2018 was 29.12 ± 17.64 ppbv declined distinctly compared to that in 2015 and 2016. Vehicle exhaust (39.95%), natural gas/liquefied petroleum gas (22.04%) and industrial sources (20.64%) were the main contributors to VOCs in Beijing. Regional transport, mainly from the south-south-east (SSE) and south-south-west (SSW), quantitatively contributed 36.65%–55.06% to VOCs based on our developed method. O3 sensitivity tended to be in the transition regime in summer identified by ground-based and satellite observations. Strong solar radiation along with high temperature and low humidity aggravated O3 pollution that was further intensified by regional transport from southern polluted regions. The model simulation determined that turning off CH3CHO related reactions brought about the most predominantly short-term and long-run O3 reduction, indicating that control policies in VOC species should be tailored, instead of one-size-fits-all. Overall, region-collaborated and active VOC-species-focused strategies on VOC controls are imperative.

Photocatalytic technologies are a potential solution for remediation of radioactive wastewater, including the reduction of radioactive hexavalent uranium, which is commonly found in wastewater from the nuclear industry. In this study, Fe2O3–graphene oxide composites were synthesized by an easy and scalable impregnation method as a catalyst for the reduction of U(VI). X-ray photoelectron spectroscopy analysis and high-resolution transmission electron microscopy images of this composite clearly showed that the Fe2O3 nanoparticles exist in the layered structure of graphene oxide. The photocatalytic activity of the Fe2O3–graphene oxide composite was evaluated by the reduction of U(VI) to U(IV) in aqueous solution under visible light. The results showed that the photocatalytic process of the Fe2O3–graphene oxide composite was always faster than that of the Fe2O3 nanoparticles. Moreover, the experimental kinetic data for the catalytic process followed a pseudo-first-order model. The stability of the Fe2O3–graphene oxide composites was studied over successive experiments, with the photocatalytic reduction efficiency of U(VI) decreasing to 76.0% after four cycles. Based on these experimental results, the enhanced photocatalytic activity and stability of Fe2O3–graphene oxide composites can be attributed to the improved adsorption properties of U(VI) at GO and the electron transfer from iron oxide to GO.

In 2015, comprehensive observations were carried out in Chengdu, Sichuan Province, China, to elucidate the seasonal variation characteristics of the concentrations, chemical compositions, and the sources of PM

Concentrations of 99 volatile organic compounds (VOCs) were continuously measured online at an urban site in Beijing, China, in January, April, July, and October 2016. Characterization and sources of VOCs and their related changes during days with heavy ozone (O3) pollution were analysed. The total observed concentration of VOCs (TVOCs) was 44.0 ± 28.9 ppbv. The VOC pollution level has decreased in Beijing but remains higher than in other Chinese cities. Alkanes comprised the highest proportion among seven major sampled VOC groups. The concentrations and sources of ambient VOCs showed obvious temporal variations. Six emission sources were identified by the positive matrix factorization (PMF), including biomass burning, coal combustion, gasoline vehicles, diesel vehicles, solvent usage, and biogenic + secondary emissions. The combustion source was the key control factor for VOC reduction in Beijing. From the potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) model, Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Shandong, and Henan were identified as major potential source regions of ambient VOCs. O3 formation was sensitive to VOCs in Beijing according to the VOC/NOx ratio (ppbC/ppbv, 8:1 threshold). High- and low-O3 days in July were identified, and high O3 levels were due to both enhanced VOC emission levels and meteorological conditions favourable to the production of O3. These findings provide evidence that the fuel combustion and regional transport have a great impact on concentrations and sources of VOCs in urban Beijing.

With the aim to conveniently evaluate the abrasive worn states in precision grinding, this paper presents an image detection and evaluation function for grinding wheel’s micro-surface recovering. Any curved object have different focus level in the same image. With a fixed focus detector drived by motor, the information of abrasive height can be extracted from image sequence by focus evaluation. We propose and compared two method and find Gray-Level-Variance (GLV) have a better robustness on wheel’s surface recovering. The arithmetic works better and smoother when LULU operator is cooperated. Finally, we make a comparision between the result of GLV and ultra-depth 3D microscope in comparative section. The information of single abrasive and diamond pellets are concerned to prove the arithmetic’s validity and stability.

To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta (PRD) region, integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17, 2014. The concentrations and chemical compositions of PM2.5, aerosol optical properties and meteorological parameters were measured. The mean value of PM2.5 increased from less than 35 (excellent) to 35-75 μg/m3 (good) and then to greater than 75 μg/m3 (pollution), corresponding to mean PM2.5 values of 24.9, 51.2, and 93.3 μg/m3, respectively. The aerosol scattering hygroscopic growth factor (f(RH = 80%)) values were 2.0, 2.12, and 2.18 for the excellent, good, and pollution levels, respectively. The atmospheric extinction coefficient (σext) and the absorption coefficient of aerosols (σap) increased, and the single scattering albedo (SSA) decreased from the excellent to the pollution levels. For different air mass sources, under excellent and good levels, the land air mass from northern Heshan had lower f(RH) and σsp values. In addition, the mixed aerosol from the sea and coastal cities had lower f(RH) and showed that the local sources of coastal cities have higher scattering characteristics in pollution periods.

Photocatalytic technologies are a potential solution for remediation of radioactive wastewater, including the reduction of radioactive hexavalent uranium, which is commonly found in wastewater from the nuclear industry. In this study, Fe

To elucidate the formation mechanism of haze and the important role of atmospheric humidity in haze formation, comprehensive observations were carried out at regional sites in the Pearl River Delta region of southern China from October 22 to November 6, 2014. Meteorological parameters, chemical compositions, aerosol secondary conversions and aerosol radiative forcing were analyzed. A lower wind speed (WS) and planetary boundary layer (PBL) can inhibit the horizontal and vertical diffusion of pollutants, leading to the accumulation of pollutant concentrations. A higher atmospheric relative humidity (RH) can promote aerosol secondary conversions, leading to an increase in secondary aerosol concentrations. Aerosol scattering hygroscopic growth properties and aerosol single scattering albedo (SSA) also increase with increasing RH, resulting in an increase in aerosol radiative forcing and a decrease in the PBL height, aggravating the formation of meteorological conditions that are not conducive to the dilution of pollutants. Conversely, a higher aerosol concentration also increases aerosol radiative forcing, forming a positive feedback loop. When the RH decreases and the WS increases, the loop enters a negative feedback process to reduce pollutant concentration.