科研成果

2019
Tang M, Guo L, Bai Y, Huang R-J, Wu Z, Wang Z, Zhang G, Ding X, Hu M, Wang X. Impacts of methanesulfonate on the cloud condensation nucleation activity of sea salt aerosol. Atmospheric EnvironmentAtmospheric Environment. 2019;201:13-17.Abstract
Methanesulfonate, an important oxidation product of dimethyl sulfide, is abundant in marine aerosol particles. However, its impact on the cloud condensation nucleation (CCN) activity of marine aerosol is yet to be elucidated, largely because the CCN activity of methanesulfonate has been seldom investigated. In this work, we measured the CCN activities of three common methanesulfonates, and the single hygroscopicity parameters (κ) were determined to be 0.46 ± 0.02 for sodium methanesulfonate (NaMS), 0.37 ± 0.01 for calcium methanesulfonate, and 0.47 ± 0.02 for potassium methanesulfonate, respectively. In addition, we explored the effect of NaMS on the CCN activities of NaCl and synthetic sea salt. It was found that if presented with a mass ratio of 1:1, NaMS would significantly reduce the CCN activities of NaCl and sea salt, and the κ values of binary mixtures could be estimated using the simple mixing rule. Nevertheless, if only presented with a mass ratio of 1:10 (an environmentally relevant value), the effect of NaMS on the CCN activities of NaCl and sea salt was found to be small. Overall, we conclude that from our experimental data and its levels found in the troposphere, methanesulfonate may only have minor impacts on the CCN activity of marine aerosol.
2018
Chen J, Pei XY, Wang H, Chen JC, Zhu YS, Tang MJ, Wu ZJ. Development, Characterization, and Validation of a Cold Stage-Based Ice Nucleation Array (PKU-INA). Atmosphere. 2018;9:13.Abstract
A drop-freeze array (PeKing University Ice Nucleation Array, PKU-INA) was developed based on the cold-stage method to investigate heterogeneous ice nucleation properties of atmospheric particles in the immersion freezing mode from -30 to 0 degrees C. The instrumental details as well as characterization and performance evaluation are described in this paper. A careful temperature calibration protocol was developed in our work. The uncertainties in the reported temperatures were found to be less than 0.4 degrees C at various cooling rates after calibration. We also measured the ice nucleation activities of droplets containing different mass concentrations of illite NX, and the results obtained in our work show good agreement with those reported previously using other instruments with similar principles. Overall, we show that our newly developed PKU-INA is a robust and reliable instrument for investigation of heterogeneous ice nucleation in the immersion freezing mode.
Nieminen T, Kerminen VM, Petaja T, Aalto PP, Arshinov M, Asmi E, Baltensperger U, Beddows DCS, Beukes JP, Collins D, et al. Global analysis of continental boundary layer new particle formation based on long-term measurements. Atmospheric Chemistry and Physics. 2018;18:14737-14756.Abstract
Atmospheric new particle formation (NPF) is an important phenomenon in terms of global particle number concentrations. Here we investigated the frequency of NPF, formation rates of 10 nm particles, and growth rates in the size range of 10-25 nm using at least 1 year of aerosol number size-distribution observations at 36 different locations around the world. The majority of these measurement sites are in the Northern Hemisphere. We found that the NPF frequency has a strong seasonal variability. At the measurement sites analyzed in this study, NPF occurs most frequently in March-May (on about 30 % of the days) and least frequently in December-February (about 10 % of the days). The median formation rate of 10 nm particles varies by about 3 orders of magnitude (0.01-10 cm(-3) s(-1)) and the growth rate by about an order of magnitude (1-10 nm h(-1)). The smallest values of both formation and growth rates were observed at polar sites and the largest ones in urban environments or anthropogenically influenced rural sites. The correlation between the NPF event frequency and the particle formation and growth rate was at best moderate among the different measurement sites, as well as among the sites belonging to a certain environmental regime. For a better understanding of atmospheric NPF and its regional importance, we would need more observational data from different urban areas in practically all parts of the world, from additional remote and rural locations in North America, Asia, and most of the Southern Hemisphere (especially Australia), from polar areas, and from at least a few locations over the oceans.
Tang MJ, Chen J, Wu Z. Ice nucleating particles in the troposphere: Progresses, challenges and opportunities. Atmospheric EnvironmentAtmospheric Environment. 2018;192:206-208.
Qiao K, Wu ZJ, Pei XY, Liu QY, Shang DJ, Zheng J, Du ZF, Zhu WF, Wu YS, Lou SR, et al. Size-resolved effective density of submicron particles during summertime in the rural atmosphere of Beijing, China. Journal of Environmental Sciences. 2018;73:69-77.Abstract
Particle density is an important physical property of atmospheric particles. The information on high time-resolution size-resolved particle density is essential for understanding the atmospheric physical and chemical aging processes of aerosols particles. In the present study, a centrifugal particle mass analyzer (CPMA) combined with a differential mobility analyzer (DMA) was deployed to determine the size-resolved effective density of 50 to 350 nm particles at a rural site of Beijing during summer 2016. The measured particle effective densities decreased with increasing particle sizes and ranged from 1.43 to 1.55 g/cm(3), on average. The effective particle density distributions were dominated by a mode peaked at around 1.5 g/cm(3) for 50 to 350 nm particles. Extra modes with peaks at 1.0, 0.8, and 0.6 g/cm(3) for 150, 240, and 350 nm particles, which might be freshly emitted soot particles, were observed during intensive primary emissions episodes. The particle effective densities showed a diurnal variation pattern, with higher values during daytime. A case study showed that the effective density of Aitken mode particles during the new particle formation (NPF) event decreased considerably, indicating the significant contribution of organics to new particle growth. (C) 2018 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.
Wu ZJ, Wang Y, Tan TY, Zhu YS, Li MR, Shang DJ, Wang HC, Lu KD, Guo S, Zeng LM, et al. Aerosol Liquid Water Driven by Anthropogenic Inorganic Salts: Implying Its Key Role in Haze Formation over the North China Plain. Environmental Science & Technology Letters. 2018;5:160-166.Abstract
This study reveals aerosol liquid water content (ALWC) in PM2.5 ranged from 2% up to 74%, and the associated secondary inorganic fraction rose from 24% to 55%, while ambient relative humidity (RH) increased from 15% to 83% in the atmosphere over Beijing. Unexpectedly, the secondary inorganic fraction in PM2.5 increased with an increase in the ambient RH, which is a meteorological parameter independent of anthropogenic activities, indicating the presence of a feedback mechanism driven by Henry's law and thermodynamic equilibrium. During haze episodes, simultaneously elevated RH levels and anthropogenic secondary inorganic mass concentrations resulted in an abundant ALWC. The condensed water could act as an efficient medium for multiphase reactions, thereby facilitating the transformation of reactive gaseous pollutants into particles and accelerating the formation of heavy haze. ALWC was well correlated with the mass concentrations of both nitrate and sulfate, indicating both nitrate and sulfate salts play key roles in determining ALWC. Coincident with a significant reduction in SO2 emissions throughout China, nitrates will become a dominant anthropogenic inorganic salt driving ALWC. Thus, the abundance of ALWC and its effects on the aerosol chemistry and climate should be reconsidered.
Chen J, Wu ZJ, Augustin-Bauditz S, Grawe S, Hartmann M, Pei XY, Liu ZR, Ji DS, Wex HK. Ice-nucleating particle concentrations unaffected by urban air pollution in Beijing, China. Atmospheric Chemistry and Physics. 2018;18:3523-3539.Abstract
Exceedingly high levels of PM2.5 with complex chemical composition occur frequently in China. It has been speculated whether anthropogenic PM2.5 may significantly contribute to ice-nucleating particles (INP). However, few studies have focused on the ice-nucleating properties of urban particles. In this work, two ice-nucleating droplet arrays have been used to determine the atmospheric number concentration of INP (N-INP) in the range from 6 to 25 degrees C in Beijing. No correlations between N-INP and either PM2.5 or black carbon mass concentrations were found, although both varied by more than a factor of 30 during the sampling period. Similarly, there were no correlations between N-INP and either total particle number concentration or number concentrations for particles with diameters > 500 nm. Furthermore, there was no clear difference between day and night samples. All these results indicate that Beijing air pollution did not increase or decrease INP concentrations in the examined temperature range above values observed in nonurban areas; hence, the background INP concentrations might not be anthropogenically influenced as far as urban air pollution is concerned, at least in the examined temperature range.
Wang HC, Lu KD, Guo S, Wu ZJ, Shang DJ, Tan ZF, Wang YJ, Le Breton M, Lou SR, Tang MJ, et al. Efficient N2O5 uptake and NO3 oxidation in the outflow of urban Beijing. Atmospheric Chemistry and Physics. 2018;18:9705-9721.Abstract
Nocturnal reactive nitrogen compounds play an important role in regional air pollution. Here we present the measurements of dinitrogen pentoxide (N2O5) associated with nitryl chloride (ClNO2) and particulate nitrate (pNO(3)(-)) at a suburban site of Beijing in the summer of 2016. High levels of N2O5 and ClNO2 were observed in the outflow of the urban Beijing air masses, with 1 min average maxima of 937 and 2900 pptv, respectively. The N2O5 uptake coefficients, gamma, and ClNO2 yield, f, were experimentally determined from the observed parameters. The N2O5 uptake coefficient ranged from 0.012 to 0.055, with an average of 0.034 +/- 0.018, which is in the upper range of previous field studies reported in North America and Europe but is a moderate value in the North China Plain (NCP), which reflects efficient N2O5 heterogeneous processes in Beijing. The ClNO2 yield exhibited high variability, with a range of 0.50 to unity and an average of 0.73 +/- 0.25. The concentration of the nitrate radical (NO3) was calculated assuming that the thermal equilibrium between NO3 and N2O5 was maintained. In NOx-rich air masses, the oxidation of nocturnal biogenic volatile organic compounds (BVOCs) was dominated by NO3 rather than O-3. The production rate of organic nitrate (ON) via NO3 + BVOCs was significant, with an average of 0.10 +/- 0.07 ppbvh(-1). We highlight the importance of NO3 oxidation of VOCs in the formation of ON and subsequent secondary organic aerosols in summer in Beijing.
Wang HC, Lu KD, Chen XR, Zhu QD, Wu ZJ, Wu YS, Sun K. Fast particulate nitrate formation via N2O5 uptake aloft in winter in Beijing. Atmospheric Chemistry and Physics. 2018;18:10483-10495.Abstract
Particulate nitrate (pNO(3)(-)) is an important component of secondary aerosols in urban areas. Therefore, it is critical to explore its formation mechanism to assist with the planning of haze abatement strategies. Here we report vertical measurements of NOx and O-3 by in situ instruments on a movable carriage on a tower during a winter heavy-haze episode (18 to 20 December 2016) in urban Beijing, China. Based on the box model simulation at different heights, we found that pNO(3)(-) formation via N2O5 heterogeneous uptake was negligible at ground level due to N2O5 concentrations of near zero controlled by high NO emissions and NO concentration. In contrast, the contribution from N2O5 uptake was large at high altitudes (e.g., > 150 m), which was supported by the lower total oxidant (NO2 + O-3) level at high altitudes than at ground level. Modeling results show the specific case that the nighttime integrated production of pNO(3)(-) for the high-altitude air mass above urban Beijing was estimated to be 50 mu gm(-3) and enhanced the surface-layer pNO(3)(-) the next morning by 28 mu gm(-3) through vertical mixing. Sensitivity tests suggested that the nocturnal NOx loss by NO3-N2O5 chemistry was maximized once the N2O5 uptake coefficient was over 2 x 10(-3) on polluted days with S-a at 3000 mu m(2) cm(-3) in wintertime. The case study provided a chance to highlight the fact that pNO(3)(-) formation via N2O5 heterogeneous hydrolysis may be an important source of particulate nitrate in the urban airshed during wintertime.
Wu ZJ, Chen J, Wang Y, Zhu YS, Liu YC, Yao B, Zhang YH, Hu M. Interactions between water vapor and atmospheric aerosols have key roles in air quality and climate change. National Science Review. 2018;5:452-454.
Wang YJ, Hu M, Guo S, Wang YC, Zheng J, Yang YD, Zhu WF, Tang RZ, Li X, Liu Y, et al. The secondary formation of organosulfates under interactions between biogenic emissions and anthropogenic pollutants in summer in Beijing. Atmospheric Chemistry and Physics. 2018;18:10693-10713.Abstract
Organosulfates (OSs) with ambiguous formation mechanisms are a potential source of "missing secondary organic aerosol (SOA)" in current atmospheric models. In this study, we chemically characterized OSs and nitrooxy-OSs (NOSs) formed under the influence of biogenic emissions and anthropogenic pollutants (e.g., NOx, SO42-) in summer in Beijing. An ultrahigh-resolution mass spectrometer equipped with an electrospray ionization source was applied to examine the overall molecular composition of S-containing organics. The number and intensities of S-containing organics, the majority of which could be assigned as OSs and NOSs, increased significantly during pollution episodes, which indicated their importance for SOA accumulation. To further investigate the distribution and formation of OSs and NOSs, high-performance liquid chromatography coupled with mass spectrometry was employed to quantify 10 OSs and 3 NOS species. The total concentrations of quantified OSs and NOSs were 41.4 and 13.8 ng m(-3), respectively. Glycolic acid sulfate was the most abundant species among all the quantified species, followed by monoterpene NOSs (C10H16NO7S-). The total concentration of three isoprene OSs was 14.8 ng m(-3) and the isoprene OSs formed via the HO2 channel were higher than those formed via the NO/NO2 channel. The OS concentration coincided with the increase in acidic sulfate aerosols, aerosol acidity, and liquid water content (LWC), indicating the acid-catalyzed aqueousphase formation of OSs in the presence of acidic sulfate aerosols. When sulfate dominated the accumulation of secondary inorganic aerosols (SIAs; sulfate, nitrate, and ammonium; SO42-/SIA > 0.5), OS formation would obviously be promoted as the increasing of acidic sulfate aerosols, aerosol LWC, and acidity (pH < 2.8). Otherwise, acid-catalyzed OS formation would be limited by lower aerosol acidity when nitrate dominated the SIA accumulation. The nighttime enhancement of monoterpene NOSs suggested their formation via the nighttime NO3-initiated oxidation of monoterpene under high-NOx conditions. However, isoprene NOSs are presumed to form via acid-catalyzed chemistry or reactive uptake of oxidation products of isoprene. This study provides direct observational evidence and highlights the secondary formation of OSs and NOSs via the interaction between biogenic precursors and anthropogenic pollutants (NOx, SO2, and SO42-). The results imply that future reduction in anthropogenic emissions can help to reduce the biogenic SOA burden in Beijing or other areas impacted by both biogenic emissions and anthropogenic pollutants.
Wang Y, Wu ZJ, Ma N, Wu YS, Zeng LM, Zhao CS, Wiedensohler A. Statistical analysis and parameterization of the hygroscopic growth of the sub-micrometer urban background aerosol in Beijing. Atmospheric EnvironmentAtmospheric Environment. 2018;175:184-191.Abstract
The take-up of water of aerosol particles plays an important role in heavy haze formation over North China Plain, since it is related with particle mass concentration, visibility degradation, and particle chemistry. In the present study, we investigated the size-resolved hygroscopic growth factor (HGF) of sub-micrometer aerosol particles (smaller than 350 nm) on a basis of 9-month Hygroscopicity-Tandem Differential Mobility Analyzer measurement in the urban background atmosphere of Beijing. The mean hygroscopicity parameter (kappa) values derived from averaging over the entire sampling period for particles of 50 nm, 75 nm, 100 nm, 150 nm, 250 nm, and 350 nm in diameters were 0.14 +/- 0.07, 0.17 +/- 0.05, 0.18 +/- 0.06, 0.20 +/- 0.07, 0.21 +/- 0.09, and 0.23 +/- 0.12, respectively, indicating the dominance of organics in the sub-micrometer urban aerosols. In the spring, summer, and autumn, the number fraction of hydrophilic particles increased with increasing particle size, resulting in an increasing trend of overall particle hygroscopicity with enhanced particle size. Differently, the overall mean it values peaked in the range of 75-150 nm and decreased for particles larger than 150 rim in diameter during wintertime. Such size-dependency of kappa in winter was related to the strong primary particle emissions from coal combustion during domestic heating period. The number fraction of hydrophobic particles such as freshly emitted soot decreased with increasing PM2.5 mass concentration, indicating aged and internal mixed particles were dominant in the severe particulate matter pollution. Parameterization schemes of the HGF as a function of relative humidity (RH) and particle size between 50 and 350 nm were determined for different seasons and pollution levels. The HGFs calculated from the parameterizations agree well with the measured FIGFs at 20-90% RH. The parameterizations can be applied to determine the hygroscopic growth of aerosol particles at ambient conditions for the area of Beijing (ultrafine and fine particles) and the North China plain (fine particles).
Hu W, Niu HY, Murata K, Wu ZJ, Hu M, Kojima T, Zhang DZ. Bacteria in atmospheric waters: Detection, characteristics and implications. Atmospheric EnvironmentAtmospheric Environment. 2018;179:201-221.Abstract
In this review paper, we synthesize the current knowledges about bacteria in atmospheric waters, e.g., cloud, fog, rain, and snow, most of which were obtained very recently. First, we briefly describe the importance of bacteria in atmospheric waters, i.e., the essentiality of studying bacteria In atmospheric waters in understanding aerosol-cloud-precipitation-climate interactions in the Earth system. Next, approaches to collect atmospheric water samples for the detection of bacteria and methods to identify the bacteria are summarized and compared. Then the available data on the abundance, viability and community composition of bacteria in atmospheric waters are summarized. The average bacterial concentration in cloud water was usually on the order 10(4)-10(5) cells mL(-1), while that in precipitation on the order 10(3)-10(4) cells mL(-1). Most of the bacteria were viable or metabolically active. Their community composition was highly diverse and differed at various sites. Factors potentially influencing the bacteria, e.g., air pollution levels and sources, meteorological conditions, seasonal effect, and physicochemical properties of atmospheric waters, are described. After that, the implications of bacteria present in atmospheric waters, including their effect on nucleation in clouds, atmospheric chemistry, ecosystems and public health, are briefly discussed. Finally, based on the current knowledges on bacteria in atmospheric waters, which in fact remains largely unknown, we give perspectives that should be paid attention to in future studies.
Tan TY, Hu M, Li MR, Guo QF, Wu YS, Fang X, Gu FT, Wang Y, Wu ZJ. New insight into PM2.5 pollution patterns in Beijing based on one-year measurement of chemical compositions. Science of the Total Environment. 2018;621:734-743.Abstract
In recent years, air pollution has become a major concern in China, especially in the capital city of Beijing. Haze events occur in Beijing over all four seasons, exhibiting distinct characteristics. In this study, the typical evolution patterns of atmospheric particulate matter with a diameter of less than 2.5 mu m (PM2.5) in each season were illustrated by episode-based analysis. In addition, a novelmethodwas developed to elucidate the driving species of pollution, which is the largest contributor to the incremental PM2.5 (triangle PM2.5), not PM2.5. This method revealed a temporal variation of the driving species throughout the year: nitrate-driven spring, sulfate-driven summer, nitrate-driven early fall, and organicmatters (OM)-driven late fall and winter. These results suggested that primary organic particles or volatile organic compounds emissions were dominant in the heating season due to residential heating, while NOx and SO2 emissions dominated in the other seasons. Besides, nitrate formation seemed more significant than sulfate formation during severe pollution episodes. It was also found that the pollution formation mechanismin the winter showed some unique features in comparison with the other seasons: aqueous reactions were more important in the winter, while multiple pathways coexisted in the other seasons. Furthermore, this study confirmed that the PM2.5 in Beijing was moderately acidic despite a fully neutralized system. In addition, the acidity variation during pollution episodes displayed different patterns between seasons and was driven by both the variation of aerosol water and chemical compositions. These results provide a new perspective to understand the characteristics and mechanisms of aerosol pollution in Beijing. However, more accurate measurements
Hu W, Niu HY, Murata K, Wu ZJ, Hu M, Kojima T, Zhang DZ. Bacteria in atmospheric waters: Detection, characteristics and implications. Atmospheric Environment. 2018;179:201-221.Abstract
In this review paper, we synthesize the current knowledges about bacteria in atmospheric waters, e.g., cloud, fog, rain, and snow, most of which were obtained very recently. First, we briefly describe the importance of bacteria in atmospheric waters, i.e., the essentiality of studying bacteria In atmospheric waters in understanding aerosol-cloud-precipitation-climate interactions in the Earth system. Next, approaches to collect atmospheric water samples for the detection of bacteria and methods to identify the bacteria are summarized and compared. Then the available data on the abundance, viability and community composition of bacteria in atmospheric waters are summarized. The average bacterial concentration in cloud water was usually on the order 10(4)-10(5) cells mL(-1), while that in precipitation on the order 10(3)-10(4) cells mL(-1). Most of the bacteria were viable or metabolically active. Their community composition was highly diverse and differed at various sites. Factors potentially influencing the bacteria, e.g., air pollution levels and sources, meteorological conditions, seasonal effect, and physicochemical properties of atmospheric waters, are described. After that, the implications of bacteria present in atmospheric waters, including their effect on nucleation in clouds, atmospheric chemistry, ecosystems and public health, are briefly discussed. Finally, based on the current knowledges on bacteria in atmospheric waters, which in fact remains largely unknown, we give perspectives that should be paid attention to in future studies.
Sun J, Liu L, Xu L, Wang Y, Wu Z, Hu M, Shi Z, Li Y, Zhang X, Chen J, et al. Key Role of Nitrate in Phase Transitions of Urban Particles: Implications of Important Reactive Surfaces for Secondary Aerosol Formation. Journal of Geophysical Research: AtmospheresJournal of Geophysical Research: Atmospheres. 2018;123:1234-1243.Abstract
Abstract Ammonium sulfate (AS) and ammonium nitrate (AN) are key components of urban fine particles. Both field and model studies showed that heterogeneous reactions of SO2, NO2, and NH3 on wet aerosols accelerated the haze formation in northern China. However, little is known on phase transitions of AS-AN containing haze particles. Here hygroscopic properties of laboratory-generated AS-AN particles and individual particles collected during haze events in an urban site were investigated using an individual particle hygroscopicity system. AS-AN particles showed a two-stage deliquescence at mutual deliquescence relative humidity (MDRH) and full deliquescence relative humidity (DRH) and three physical states: solid before MDRH, solid-aqueous between MDRH and DRH, and aqueous after DRH. During hydration, urban haze particles displayed a solid core and aqueous shell at RH = 60?80% and aqueous phase at RH > 80%. Most particles were in aqueous phase at RH > 50% during dehydration. Our results show that AS content in individual particles determines their DRH and AN content determines their MDRH. AN content increase can reduce MDRH, which indicates occurrence of aqueous shell at lower RH. The humidity-dependent phase transitions of nitrate-abundant urban particles are important to provide reactive surfaces of secondary aerosol formation in the polluted air.
Liu M, Huang X, Song Y, Xu T, Wang S, Wu Z, Hu M, Zhang L, Zhang Q, Pan Y, et al. Rapid SO2 emission reductions significantly increase tropospheric ammonia concentrations over the North China Plain. Atmospheric Chemistry and Physics. 2018;18:17933-17943.
Huang S, Wu Z, Poulain L, van Pinxteren M, Merkel M, Assmann D, Herrmann H, Wiedensohler A. Source apportionment of the organic aerosol over the Atlantic Ocean from 53°&thinsp;N to 53°&thinsp;S: significant contributions from marine emissions and long-range transport. Atmospheric Chemistry and Physics. 2018;18:18043-18062.
吴志军、陈洁.; 2018. 浸润核模式下的冰核浓度及成冰活性检测装置离线检测装置. China patent CN ZL201721531688.1 .
2017
Wu ZJ. Gain Insight into Chemical Components Driving New Particle Growth on a Basis of Particle Hygroscopicity and Volatility Measurements: a Short Review. Current Pollution Reports. 2017;3:175-181.Abstract
Atmospheric new particle formation and growth play important roles in climate change and air quality. Aiming at better understanding the particle growth mechanisms, the measurements on chemical composition of new particles are imperative. However, the instruments directly detecting chemical composition of nanoparticles (<30 nm) are very rare due to the tiny particle masses involved and low transmission efficiency. Alternatively, the hygroscopicity and volatility of nanoparticles were measured to infer chemical composition of the particle. Here, we summarized the progresses in studying the new particle growth processes on a basis of particle hygroscopicity and volatility measurements. Compared to clean environments, such as in boreal forest, the water soluble components contribute a larger fraction of newly formed particles (below 50 nm) in the polluted environments, such as in the sulfur-rich atmosphere of North China Plain. The extreme low volatility components in new particles were observed in both clean and polluted environments and contributed to 1/4 of particle growth in a rural site of Melpitz, Germany. In the future, the instruments capable of precisely detecting the hygroscopicity and volatility of particles below 10 nm are needed. Except for differential mobility analyzer, other novel methods without limitation of charging and transmission efficiency should be considered. The hygroscopicity and volatility of atmospheric relevant compounds should be investigated in the laboratory in order to provide supportive information to explain the hygroscopicity and volatility of new particle in the ambient air.

Pages