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This review summarizes the recent progress in interfacial solar vapor generation, which was first proposed in 2014. The technique shows great potential for decentralized desalination applications using ubiquitous and renewable solar energy.

Automatic recognition and positioning of electronic components on PCBs can enhance quality inspection efficiency for electronic products during manufacturing. Efficient PCB inspection requires identification and classification of PCB components as well as defects for better quality assurance. The small size of the electronic component and PCB defect targets means that there are fewer feature areas for the neural network to detect, and the complex grain backgrounds of both datasets can cause significant interference, making the target detection task challenging. Meanwhile, the detection performance of deep learning models is significantly impacted due to the lack of samples. In this paper, we propose conditional TransGAN (cTransGAN), a generative model for data augmentation, which enhances the quantity and diversity of the original training set and further improves the accuracy of PCB electronic component recognition. The design of cTransGAN brings together the merits of both conditional GAN and TransGAN, allowing a trained model to generate high-quality synthetic images conditioned on the class embeddings. To validate the proposed method, we conduct extensive experiments on two datasets, including a self-developed dataset for PCB component detection and an existing dataset for PCB defect detection. Also, we have evaluated three existing object detection algorithms, including Faster R-CNN ResNet101, YOLO V3 DarkNet-53, and SCNet ResNet101, and each is validated under four experimental settings to form an ablation study. Results demonstrate that the proposed cTransGAN can effectively enhance the quality and diversity of the training set, leading to superior performance on both tasks. We have open-sourced the project to facilitate further studies.

Tailpipe emissions from three heavy-duty diesel vehicles (HDDVs), complying with varying emission standards and installed with diverse aftertreatment technologies, are collected at a certified chassis dynamometer laboratory. The HDDV-emitted intermediate-volatility and semi-volatile organic compound (I/SVOC) emission and the gas–particle partitioning of the I/SVOCs are investigated. Over 4000 compounds are identified and grouped into 21 categories. The dominant compound groups of particulate I/SVOCs are alkanes and phenolic compounds. For HDDVs without aftertreatment devices, i.e., diesel oxidation catalysts (DOCs) and diesel particulate filters (DPFs), the emitted I/SVOCs partition dramatically into the gas phase (accounting for ∼ 93 % of the total I/SVOC mass), with a few exceptions: hopane, four-ring polycyclic aromatic hydrocarbons (PAH4rings), and five-ring polycyclic aromatic hydrocarbons (PAH5rings). For HDDVs with DPFs and DOCs, the particulate fractions are reduced to a negligible level (i.e., less than 2 %). Nevertheless, 50 % of the total two-ring PAH mass is detected in the particle phase, which is much higher than the high-molecular-weight PAHs, arising from the positive sampling artifact of quartz filter absorbing organic vapors. The positive sampling artifact of quartz filter absorbing organic vapors is clearly observed, and uncertainties are discussed and quantified. Particulate I/SVOCs at low-speed, middle-speed, and high-speed phases are collected and analyzed separately. The emission factor (EF) distribution of the speciated organic aerosol (OA) on a two-dimensional volatility basis set (2D-VBS) space reveals that the fractions of OA with oxygen to carbon (O : C) ratios > 0.3 (0.4, 0.5) are 18.2 % (11.5 %, 9.5 %), 23 % (15.4 %, 13.6 %), and 29.1 % (20.6 %, 19.1 %) at the low-speed, middle-speed, and high-speed stages. These results help to resolve complex organic mixtures and trace the evolution of OA.

Tailpipe emissions from three heavy-duty diesel vehicles (HDDVs), complying with varying emission standards and installed with diverse aftertreatment technologies, are collected at a certified chassis dynamometer laboratory. The HDDV-emitted intermediate-volatility and semi-volatile organic compound (I/SVOC) emission and the gas-particle partitioning of the I/SVOCs are investigated. Over four thousand compounds are identified and grouped into twenty-one categories. The dominant compound groups of particulate I/SVOCs are alkanes and phenolic compounds. For HDDVs without aftertreatment devices, i.e., diesel oxidation catalyst (DOC) and diesel particulate filter (DPF), the emitted I/SVOCs partition dramatically into the gas phase (accounting for ~ 93 % of the total I/SVOC mass), with a few exceptional categories: hopane, 4-ring polycyclic aromatic hydrocarbons (PAH4rings), and PAH5rings. For HDDVs with DPF and DOC, the particulate fractions are reduced to a negligible level, i.e., less than 2 %. Nevertheless, 50 % of the total 2-ring PAH mass is detected in the particle phase, which is much higher than the high-molecular-weight PAHs, arising from the positive sampling artifact of quartz filter absorbing organic vapours. The positive sampling artifact of quartz filter absorbing organic vapors is clearly observed and uncertainties are discussed and quantified. Particulate I/SVOCs at low-speed, middle-speed, and high-speed phases are collected and analysed separately. EF distribution of the speciated OA on a two-dimensional volatility basis set (2D-VBS) space reveals that the fractions of OA with O : C (oxygen to carbon) ratio > 0.3 (0.4, 0.5) are 18.2 % (11.5 %, 9.5 %), 23 % (15.4 %, 13.6 %), and 29.1 % (20.6 %, 19.1 %) at low-speed, middle-speed, and high-speed stages. The results help to resolve the complex organic mixtures and trace the evolution of OA.

Intermediate-volatility and semi-volatile organic compounds (I/SVOCs) are key precursors of secondary organic aerosol (SOA). However, the comprehensive characterization of I/SVOCs has long been an analytical challenge. Here, we develop a novel method of speciating and quantifying I/SVOCs using two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS) by constructing class-screening programs based on their characteristic fragments and mass spectrum patterns. Using this new approach, we then present a comprehensive analysis of gaseous I/SVOC emissions from heavy-duty diesel vehicles (HDDVs). Over three-thousand compounds are identified and classified into twenty-one categories. The dominant compound groups of I/SVCOs emitted by HDDVs are alkanes (including normal and branched alkanes, 37-66%), benzylic alcohols (7-20%), alkenes (3-11%), cycloalkanes (3-9%), and benzylic ketones (1-4%). Oxygenated I/SVOCs (O-I/SVOCs, e.g., benzylic alcohols and ketones) are first quantified and account for20% of the total I/SVOC mass. Advanced aftertreatment devices largely reduce the total I/SVOC emissions but increase the proportion of O-I/SVOCs. With the speciation data, we successfully map the I/SVOCs into the two-dimensional volatility basis set space, which facilitates a better estimation of SOA. As aging time goes by, approximate 45% difference between the two scenarios after seven-day aging is observed, which confirms the significant impact of speciated I/SVOC emission data on SOA prediction.

This experimental investigation aims to enhance the performance of heat pipes through nanoengineering the evaporator section, by integrating hydrophilic copper oxide (CuO) nanowires on the inner surface. Two types of CuO nanowires have been employed. Copper pipes measuring 440 mm in length with 12.7 mm O.D. and 0.8 mm wall thickness with inner grooves were used to manufacture heat pipes. All heat pipes were charged with ultra-filtered deionized (DI) water as a working fluid. By employing the hydrophilic CuO nanowires coating in the evaporator section of a heat pipe, its performance is substantially enhanced compared to a heat pipe with identical dimensions without the coating. Specifically, thermal resistance is reduced by 81.2% when using Type I CuO and 72% using Type II CuO nanowires compared to a heat pipe without coatings. The effects of the working load and orientation on the heat pipe thermal resistance have been systematically examined.

Air cooling system (ACS) gains more attention because of the global water crisis, however its applications are limited by the inherent low heat transfer coefficient of air. Evaporative heat transfer is promising to address the challenge in ACS. By mimicking the primary mechanism of mammals to effectively dissipate heat during physical exercise, a sweating-boosted air cooling (SBAC) strategy is proposed and experimentally demonstrated on plain walls in our previous study. We have shown that the copper oxide (CuO) wicks played a critical role in the thermal performance of SBAC. In this research, we develop superwetting copper hydroxyl nitrate (Cu-HDS/NO3) wicks to further enhance SBAC on finned copper tubes. Cu-HDS/NO3 crystals are directly synthesized on copper substrates via a three-step wet chemical oxidization process. The time-dependent surface morphology and crystal structures of Cu-HDS/NO3 are characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The newly developed wicks are superior in spreading water and thermally stable for SBAC under a wide range of working conditions. The performance of SBAC on a finned copper tube coated with Cu-HDS/NO3 wicks has been experimentally evaluated. The SBAC on as-developed wicks enhances the effective heat transfer coefficient (HTC) by 379.9% and reduces the total thermal resistance by 76.1%. The effects of wall temperature and air velocity on the thermal performance of SBAC are systematically characterized. We have shown that the super wicking capacity well complements the SBAC at low air velocity, hence makes the super wicking Cu-HDS/NO3 more attractive in the practical applications of SBAC. The developed Cu-HDS/NO3 wicks are promising in implementing SBAC strategy over current ACS.

This research systematically studies the impacts of thermal conductivity and density of phase change materials (PCM) on the characteristics of PCM-based thermal energy storage systems (TES). We show that the eutectic PCM, owing to its high thermal conductivity, has more stable temperature evolution than that of paraffin wax during both heat charging and discharging processes. The paraffin wax has an enhanced charging rate, when the heat is applied at the bottom, as a result of convection driven by the obvious temperature-dependent density of liquid paraffin wax. The convection and orientation effects are significant in the charging process of paraffin wax, but insignificant for eutectic PCM, which are further confirmed by visualization and numerical studies. Specifically, a gap forms between the covered plate wall and the solid paraffin wax after discharging process. This gap significantly inhibits the charging process in a heat charging and discharging cycle. We also observed that the charging efficiency of the paraffin wax is substantially reduced by its high contact thermal resistance, which is 2–3 orders of magnitude higher than that of eutectic PCM. This shows that rapid thermal energy charging/discharging rates, a highly desirable stable working temperature, and orientation-insensitivity of TES can be achieved using PCM with a high thermal conductivity and a temperature-independent density.

Household combustion of biomass straw for cooking or heating is one of the most important emission sources of intermediate volatility and semi-volatile organic compounds (I/SVOCs). However, there are limited studies on the emission factors (EFs) and speciation profiles of I/SVOCs from household stoves burning biomass straw. In this study, experiments were conducted in a typical Chinese stove to test the EFs and species of I/SVOCs in three commonly used straws. It was revealed that EFs of I/SVOCs emitted from the burning of corn straw, rice straw, and wheat straw were 6.7, 1.9, and 9.8 g/kg, respectively, which accounted for 48.3 %, 36.8 %, and 48.6 % of total organic compounds emitted. Particulate organic compounds were dominated by ketones, oxygenated aromatics, acids, esters, and nitrogen-containing compounds, whereas the gaseous phase was dominated by aldehydes, acids, and aromatics. Although I/SVOCs only accounted for 18.1-23.6 % of the gaseous emissions from burning of straw, they represented 64.8-72.9 % of the secondary organic aerosol formation potential (SOAFP). The EFs of 16 priority polycyclic aromatic hydrocarbons (PAHs) were 362.0, 262.5, and 1145.2 mg/kg for corn straw, rice straw, and wheat straw, respectively, among which 3-ring and 4-ring PAHs were the main components. Thus, the results of this study provide new reliable I/SVOCs data that are useful for the development of an accurate emission inventory of organic compounds, simulation of secondary organic aerosol (SOA) formation, and health risk assessment.

A mask that creates a physical barrier to protect the wearer from breathing in airborne bacteria or viruses, reducing the risk of infection in polluted air and potentially contaminated environments, has become a daily necessity for the public especially as COVID-19 has exploded around the world. However, the use of masks often causes soaring temperatures and thick humid air, leading to thermal and wear discomfort and breathing difficulties for a number of people, and further increasing the elevated risk of heat illnesses including heat stroke and heat exhaustion. When wearers become highly active or work under high tension, the excess sweat generated negatively affects the functionality of masks. Here, we report on an innovative design of an air-conditioned mask (AC Mask) system, facilitating thermoregulation in the mask microclimate, ease of breathing, and wear comfort. The AC Mask system is developed by integrating a cost-effective and lightweight thermoelectric (TE) and ventilation unit in a wearable 3D printed mask device, compatible with existing disposable masks, to protect end users safely against toxic particles such as viruses. A wind-guided tunnel has been developed for quick and efficient ventilation of cooling air. Based on a human trial, reductions in the apparent microclimate temperature and the humidity by 3.5 °C and 50%, respectively, have been achieved under a low voltage. With the excellent thermal management properties, the AC Mask will find also wide application among professional end-users such as construction workers, firefighters, and medical personnel., Graphical abstract Image 1

This experimental test investigates the effect of filling ratio (FR) and inclination angle on the thermal performance of a nanoengineered copper-water heat pipe. A hydrophilic copper oxide coating (CuO) is synthesized and integrated on the inner wall of the evaporation section of the heat pipe. The heat pipe is fabricated from an inner grooved copper pipe with dimensions of 12.7 mm outer diameter, 11 mm inner diameter, and 440 mm length. Ultra-filtered de-ionized (DI) water is used as a working fluid. Four different FRs of DI water 3%, 5%, 10%, and 15% are investigated to determine the optimum configuration. All samples are tested at various inclination angles and working loads. Experimental results show that the optimum filling ratio is the 5% FR, which was indicated by the lowest thermal resistance of 0.019 K/W.

Comprehensive characterization of diesel vehicle emitted polycyclic aromatic hydrocarbon (PAH) emissions is yet to achieve due to the limitation of analytical methods. Therefore, we herein developed a two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-ToF-MS) method and quantified the total PAHs from diesel vehicles based on their characteristic fragments and mass spectral patterns. Overall, the emission factors (EFs) of total PAHs (gas + particle) are observed to range from 4.1 ± 2.5 mg km

This paper presents an alkaline corrosion treatment for axially grooved aluminium wicks, which significantly enhances the capillary performance of these wicks and increases the applicability of axially grooved aluminium heat pipes in space or in a horizontal direction. The effect of corrosion parameters (molar concentration and reaction time) on the capillary performance was investigated. An IR camera was used to build a capillary rate-of-rise test apparatus to measure the capillary performance of corroded wicks. Experimental results indicate that the corroded-aluminium grooved wicks always present higher capillary pressures than non-corroded ones. However, care should be taken to control the molar concentration and reaction time such that the best capillary performance can be achieved. In this study, the optimal corrosion parameters were found to be 1.25 mol/L NaOH for 10 min (noted as N1.25-10), which resulted in the best capillary performance parameter (ΔPcap·K) of 8.97 ± 0.38 × 10−7 N. This finding demonstrated an enhancement of 155% compared with the value of 3.51 ± 0.1 × 10−7 N for the non-corroded wicks. Furthermore, a novel prediction method was proposed to calculate the capillary heat transfer limit of heat pipes based on IR rate-of-rise tests on wicks. The calculated corresponding heat pipe capillary limit (Qc, max) of the sample N1.25-10 reached the maximum value of 9.00 W ± 4.25%, far exceeding the value of 3.52 W ± 1.5% for the non-corroded wicks. The underlying mechanism of the enhancement is associated with the micro-coarse-structured morphology and improved hydrophilicity of the corroded aluminium surface. This study demonstrates that alkaline corrosion treatment is an easy and effective way to improve the capillary performance of grooved aluminium wicks and the capillary heat transfer limit of grooved aluminium heat pipes.

In this study, a novel type of partially-hybrid mesh-groove wicking structures have been proposed to enhance L-shaped copper-ethanol heat pipes. Enhancements come from two aspects: (a) the enhanced evaporation via a hybrid mesh-groove wicking structure and (b) the promoted condensation by managing the unwanted flooding in the condensation section. Experimental studies have been conducted to optimize the hybrid mesh-groove wicking structures. Three types of wicking structures including grooves, partially-hybrid mesh-grooves, and fully-hybrid mesh-grooves are studied and compared. The results show that the heat pipe with partially-hybrid wicking structures substantially outperforms heat pipes with the other two types of wicking structures. The thermal resistance of the heat pipe with a partially-hybrid wicking structure has been reduced up to 57.4% compared to that of the heat pipe with axially grooves. Moreover, in this study, in order to optimize the wicking structures, the effect of mesh-layers number and charging ratio on the L-shaped partially-hybrid mesh-groove wicked heat pipe (LPHHP) has been investigated. The optimal mesh-layer numbers of the LPHHP are found to be 1-2 layers. More importantly, instead of a specific value for a given heat pipe in existing studies, this study shows that the optimal charging ratio is actually a region, which highly depends on heat loads. However, it is extremely challenging to optimize a heat pipe with such a complicated wicking structure theoretically or numerically due to the involved complex two-phase heat transfer. Thus, a regression analysis method in machine learning is proposed to optimize the charging ratio of the LPHHP.

Flow boiling in microchannels is one of the most desirable cooling solutions for high power electronics. However, it is challenging to promote the flow boiling performance, particularly critical heat flux (CHF), due to their unfavorable liquid rewetting. Inlet restrictors (IRs) have been successfully used to manage two-phase instabilities in flow boiling in microchannels. However, IRs would result in extremely high pressure drop. In this study, without using IRs, parallel microgrooves (W=50 µm, H=250 µm, L=10 mm) are fabricated on the bottom surface of five parallel microchannels (W=200 µm, H=250 µm, L=10 mm) to effectively manage two-phase flow instabilities without sacrificing pressure drop. Our visualization study shows that these microgrooves can enable rewetting at highhigh frequencies up to 151 Hz and enhance thin film evaporation with the highest thin film ratio of 0.65. A highly desirable periodic rewetting mechanism can substantially delay CHF conditions and enhance heat transfer rates. Flow boiling in the present microchannel configuration has been systematically characterized with mass flux ranging from 100 kg/m2s to 600 kg/m2s. Compared to plain-wall microchannels, flow boiling heat transfer coefficient (HTC) is enhanced up to ~72% at a mass flux of 210 kg/m2s due to the sustainable thin film evaporation. Moreover, CHF is substantially enhanced by ~155% at a mass flux of 389 kg/m2s due to the rapid and periodic rewetting enabled by these decorated microgrooves. We also observed that the enhancement of HTC fades when mass flux exceeds 346 kg/m2s due to flooding.

Air-cooled condensers (ACCs) in thermal power plants are more competitive than the water-cooled condensers (WCCs) in addressing the global water crisis. The state-of-art ACCs need emerging heat transfer enhancement technologies, so hybrid wet/dry cooled condensers (HCCs) are employed to compensate for the low efficiency of ACCs. We propose a heat pipe air-cooled condenser (HPACC) to overcome the high capital and operating cost of traditional HCCs. HPACC combines the proven heat pipe technology with a novel sweating-boosted air-cooling strategy. Its architecture is similar to the most efficient once-through WCCs, but replacing conventional water tubes with high-performance heat pipes. A laboratory scale HPACC is built by scaling down the prototype of the proposed HPACC. This study evaluates the heat transport and rejection process within an HPACC. The thermal performance of HPACC is characterized under various heat loads and air velocities, and the sweating-boost effects on the HPACC are investigated. Our study shows that a saturated heat load on the HPACC exists under given air-cooling conditions. The minimum overall thermal resistance of HPACC is 4.7439 × 10−2 K/W achieved at an effective heat load of 1606.40 W with an air velocity of 3.0 m/s. Air cooling is further boosted by the sweating process on the fined surface integrated with superwetting copper hydroxyl nitrate wicks (Cu2(OH)3NO3). It demonstrates that HPACC with a sweating-boosted air cooling (HPACC-SB) significantly improves the total effective heat load by 172.17% and reduces the overall thermal resistance by 64.27%. The proposed HPACC is promising in replacing current cooling equipment of thermal power plants. Moreover, substantial water savings will help alleviate the water crisis facing the world.

The semi-diurnal mean aerosol mass concentration, chemical composition, and optical properties of PM2.5 were investigated in Shanghai during the spring of 2012. Slight pollution was observed during the study period. The average PM2.5 concentration was 64.11 ± 22.83 μg/m3. The mean coefficients of extinction, scattering, and absorption at 532 nm were 125.9 ± 78.5, 91.1 ± 56.3, and 34.9 ± 23.6 Mm−1, respectively. A relatively low mean single scattering albedo at 532 nm (0.73 ± 0.04) and low level of elemental carbon (EC, 2.67 ± 1.96 μg/m3) suggested that the light absorption was enhanced due to the internal mixing of the EC. Sulfate contributed the most to aerosol light scattering in Shanghai. The chemical composition of PM2.5 was dominated by particulate organic matter, sulfate, nitrate, ammonium, and EC. Anthropogenic sources made a significant contribution to the emission and loading of the particulate pollutants. A relatively good correlation between the aerosol chemical composition and the cloud condensation nuclei (CCN) activation indicated that aerosol chemistry is an important factor that influences the saturated hygroscopicity and growth of the aerosol.

Cloud condensation nuclei (CCN) and aerosols were measured continuously at an urban site of Shanghai in the period of September 2010–August 2011. Over the entire campaign, annual averages of CCNs at 0.2–1.0% supersaturation (SS) roughly ranged from 4000 cm−3 to 8000 cm−3. CCNs (0.2% SS) varied in a remarkable pattern on monthly or seasonal time scales, showing higher in spring and winter and lower in summer and autumn. High CCN events occurred frequently in spring (21 out of 30 days) and winter (19 out of 30 days) rather than other seasons. The diurnal variation of CCNs popularly showed a pronounced bi-modal pattern in spring, summer and winter while a uni-modal pattern in autumn. The apparent activation diameter was below 100 nm at 0.8% SS regardless of their chemical composition, whereas few particles in diameter smaller than 30 nm were activated. The activation ratio (CCN/CN) at 0.8% SS varied within 0.1–0.9 with an average of 0.47. The CCN activity of CN particles indicated a strong dependence on first aerosol size, which can explain its fundamental changes, and second aerosol chemical composition. High CCN levels were usually observed in the period of particulate pollution (e.g. haze), during which CCN increased up 2.0 times in hazy days higher than clear days, revealing a significant influence of aerosols on CCN in the atmospheric planet boundary.

Advanced thermal management solutions for various applications have promoted the development of composite wicks for two-phase heat transfer devices (TPHTDs). In this study, a number of composite wicks by covering a layer of sintered copper powder on micro V-grooves were developed. A ploughing–extrusion (P–E) method, as a material-saving fabrication means, was utilized to process the micro V-grooves on copper plate as the base of composite wicks. Using an infrared (IR) thermal imaging method, the capillary rate-of-rise tests with ethanol and acetone were carried out to characterize the capillary performance, which integrates both capillary pressure and permeability. The effects of fabrication parameters, including groove depth and pitch, sintering temperature and time, on the capillary performance of composite wicks were focused on and examined for the purpose of design optimization. Test results show that there is an optimal groove geometry with the groove depth of 0.85 mm and pitch of 0.45 mm to achieve the maximum capillary performance, and sintering processes of 950 °C along with 30 min should be chosen. Both working liquid test results exhibit fairly good agreement and demonstrate that the IR thermal imaging provides an accurate means to evaluate the hydraulic properties of composite wicks.

The potential impacts of agricultural fires (agri-fires) on regional air quality over China were examined using active fire products derived from satellite remote sensing and air mass trajectory modeling from 2009 to 2010. Agri-fires were found in most administrative areas. More than 80% of the agri-fires were in the heartlands of agricultural regions such as Anhui, Jiangsu, Shandong and Henan Provinces. Agri-fires had a seasonal pattern, with two distinct peaks in summer and autumn harvest periods, especially in June (61–86%) and October (5–14%). Agri-fire smoke was transported in the atmosphere on a continental scale in three directions, moving northeasterly, northwesterly and southwesterly away from source areas. Particles from agri-fire smoke contributed more than 35% of aerosol optical depth (AOD) over regions of the Jiaodong Peninsular, the North Plain, East China and other areas, and exceeded 60% in some areas of Shandong, Henan and Jiangsu Provinces. In the boundary layer atmosphere, particles from agri-fire smoke contributed more than 29% of PM10 in parts of Anhui, Jiangsu and Shandong Provinces. Due to agri-fires the amount of PM10 was highly correlated (R2 = 0.6) with the smoke air masses in the main potential sink regions, and the mean PM10 during the summer harvest of 2010 reached 0.24 mg/m3, far higher than the adjacent periods without smoke.

A composite wick by covering a layer of sintered copper powder on micro V-grooves was developed for two-phase heat transfer devices. Capillary performance of the composite wicks, which integrates both permeability and capillary pressure, was experimentally examined by comparing with normal sintered and grooved wicks. Forced liquid flow tests with deionized water were conducted to determine the permeability. Using a novel infrared (IR) thermal imaging method, the capillary rate-of-rise tests with ethanol were carried out to characterize the capillary performance of wicks. Two kinds of powder with spherical and irregular shapes, and four different particle size of

Aerosol optical properties were continuously measured at an urban site in Shanghai of China from December 2010 to March 2011, and aerosol scattering (σscat) and absorption (σabs) coefficients and single scattering albedo (SSA) were examined. During the entire period, mean σscat, σabs, SSA were 293 Mm− 1, 66 Mm− 1 and 0.81, respectively. Higher σscat and σabs occurred in December while relatively lower values were observed in March, and SSA was just opposite to them. σscat and σabs coefficients behaved an apparent bi-peak pattern in diurnal variation: maxima of 319, 76 Mm− 1 at 8:00 LT during traffic rush hours and sub-maxima of 280, 71 Mm− 1 at 20:00 LT. SSA also behaved a bi-peak diurnal cycle with maximum 0.85 at 13:00 LT and sub-maximum 0.82 at 4:00 LT. σscat and σabs coefficients showed a clear negative correlation with atmospheric visibility. PM2.5 and black carbon were major contributors to large optical parameters because their concentrations were 2 times higher during haze episode than in clean days. σscat and σabs were low in magnitude when northeasterly winds bring “clean” air from the China Yellow Sea arriving the observation site, and were relatively high when air masses from the north or northwest pass through continental areas or/and industrial regions, indicating impacts of various aerosol origins on aerosol optical properties.

3and 64 µm 3 /cm 3 , respectively. Aitken particles dominated the total number of particles, and accumulated particles were the greatest contributor to particle surface area. Particle number size distributions could be characterized by multi-lognormal functions. The average number size distributions of aerosols revealed a clear diurnal pattern of two peaks within 30–60 nm corresponding to the morning and afternoon traffic rush hours. All size particles had two peaks in mean number concentrations during the rush hours, and 10–20 nm and 20–50 nm particles had one additional peak in late morning. The new particle formation events were found on four days out of 73. The apparent formation rates varied from 0.2 to 0.5 cm 3 /s, and the growth rates of newly formed particles were 3.3–5.5 nm/h. Overall, the new particle formation events had a significant impact on particle size spectra in the nucleation and Atiken modes, but insignificant effects on particle surface and volume concentrations.

An online analyzer for Monitoring for AeRosols and Gases (MARGA) was employed to measure major water-soluble (WS) inorganic ions in PM10 at 1-h time resolution in Shanghai from May 27 to June 16, 2009. During the field campaign, hazy days were encountered over which atmospheric visibility was commonly less than 10 km, and hourly average PM10 reached peaks of exceeding 150 μg m −3 . Based on WS ions and pollution gases, the haze events were classified as biomass burning induced, complicated and secondary aerosol pollutions depending on their distinct formation schemes. During the biomass burning induced pollution, which was aroused from biomass burning plume, the concentration of K + was increasing up to maximum about 19 times higher than the average of clear days, and K + behaved a strong positive linear correlation with Cl − . Because of sulfate and nitrate significantly enhanced by secondary production, in which precursor gases of SO 2 and NO 2 were converted into SO 4 2− and NO 3 − on the surface of pre-existing KCl particles, the complicated pollution was responsible for a combining contribution of aerosols directly transported from biomass burning sources and known secondary aerosols linked to local emission. Under high atmospheric oxidation ability and steady atmosphere condition, the secondary pollution resulted from a significant increase of sulfate and nitrate aerosols which were oxidized from large amounts of anthropogenic gases of SO 2 and NO 2 in the urban atmosphere.

Forest wildfires have become a growing concern due to their significant effects on regional climate and air quality. In the summer of 2010, intense forest wildfires lasting for about one month occurred in Moscow and its surround regions and caused serious air pollutions. Wildfire smoke spiraled upward over western Russia and then dispersed in the atmosphere in three directions of northwestern, eastern and southern. Smoke transported a long range in the tropospheric atmosphere finally covered vast areas including western Russia and Central Asia, and part of Asian Russia, eastern Europe and Scandinavia Peninsula. Moscow and its surrounding regions was most important potential sink influenced by smoke outflows. Some smoke arrived in the Arctic and Northeast China, which would impact local climate changes.