Xingnan Ye

Particle Size Distribution and Polycyclic Aromatic Hydrocarbons Emissions from Agricultural Crop Residue Burning

Laboratory measurements were conducted to determine particle size distribution and polycyclic aromatic hydrocarbons (PAHs) emissions from the burning of rice, wheat, and corn straws, three major agricultural crop residues in China. Particle size distributions were determined by a wide-range particle spectrometer (WPS). PAHs in both the particulate and gaseous phases were simultaneously collected and analyzed by GC-MS. Particle number size distributions showed a prominent accumulation mode with peaks at 0.10, 0.15, and 0.15 μm for rice, wheat, and corn-burned aerosols, respectively. PAHs emission factors of rice, wheat, and corn straws were 5.26, 1.37, and 1.74 mg kg(-1), respectively. It was suggested that combustion with higher efficiency was characterized by smaller particle size and lower PAHs emission factors. The total PAHs emissions from the burning of three agricultural crop residues in China were estimated to be 1.09 Gg for the year 2004.

Important role of ammonia on haze formation in Shanghai

A haze episode occurred on 12 September 2009 in Shanghai, when the mass ratio of PM1.0/PM2.5 (PM: particulate matter) reached 0.8. A similar variation of hygroscopic growth factor distribution was observed for Aitken mode particles and accumulation mode particles, implying that the enhancement of fine particles was caused by local atmospheric processing. The hygroscopicity measurements in combination with chemical analysis provided strong support for the significant contribution of (NH4)2SO4 and NH4NO3 to the haze episode. The molar ratio of [NH + ]/([NO − ]+ 2[SO 2− 4 ]) rose up to 0.96, coincident with the large increase in NH3 concentration, suggesting that the available NH3 played a vital role in the enhancement of particulate sulfate and nitrate during the haze episode.

Effects of amines on particle growth observed in new particle formation events

Particle size distributions in the range of 0.01–10 µm were measured in urban Shanghai in the summer of 2013 using a Wide-range Particle Spectrometer (WPS). Size-segregated aerosol samples were collected concurrently using a Micro-Orifice Uniform Deposit Impactor (MOUDI), which aided our in-depth understanding of the new particle formation (NPF) mechanism in the polluted Yangtze River Delta area. During the observations, 16 NPF events occurred at high temperatures (~34.7°C) on clear and sunny days. In the ammonium-poor PM1.0 (particulate matter less than 1.0 µm), sulfate and ammonium accounted for 92% of the total water-soluble inorganic species. Six aminiums were detected in these MOUDI samples, among which the group of diethylaminium and trimethylaminium (DEAH+ + TMAH+) was the most abundant. The very high level of aminiums (average concentration up to 86.4 ng m−3 in PM1.8), together with highly acidic aerosols, provided insight into the frequent NPF events. The high mass ratio of total aminiums to NH4+ (>0.2 for PM0.056) further highlighted the important role of amines in promoting NPF. The concentration of DEAH+ + TMAH+ in new particles below 180 nm was strongly correlated with aerosol phase acidity, indicating that acid-base reactions dominated the aminium formation in NPF events. The unexpected enhancement of DEAH+ + TMAH+ on a nonevent day was attributed to the transportation of an SO2 plume. Our results reveal that the heterogeneous uptake of amines is dominated by the acid-base reaction mechanism, which can effectively contribute to particle growth in NPF events.

Online single particle analysis of chemical composition and mixing state of crop straw burning particles: from laboratory study to field measurement

Fresh straw burning (SB) particles were generated in the laboratory by the combustion of rice straw and corn straw. The chemical composition and mixing state of the fresh SB particles were investigated by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS). Based on the mass spectral patterns, the SB particles were clustered into four major types: Salt, Organic Carbon (OC), Elemental Carbon (EC), and internally mixed particles of EC and OC (EC-OC). In addition, particles containing ash, polycyclic aromatic hydrocarbons, heavy metals or nicotine were also observed. Physical and chemical changes of the SB particles immediately after the emission were analyzed with highly time-resolved data. During the aging processes, the average particle size increased steadily. Freshly emitted organic compounds were gradually oxidized to more oxygenated compounds in the OC-containing particles. Meanwhile, an important displacement reaction (2KCl + SO42− → K2SO4 + 2Cl−) was observed. The marker ions for SB particles were optimized and applied to identify the SB particles in the ambient atmosphere. The fluctuation of the number fraction of ambient SB particles sorted by ATOFMS agrees well with that of water soluble K+ measured by an online ion chromatography, demonstrating that the optimized marker ions could be good tracers for SB particles in field measurements.

Hygroscopicity and optical properties of alkylaminium sulfates.

The hygroscopicity and optical properties of alkylaminium sulfates (AASs) were investigated using a hygroscopicity tandem differential mobility analyzer coupled to a cavity ring-down spectrometer and a nephelometer. AAS particles do not exhibit a deliquescence phenomenon and show a monotonic increase in diameter as the relative humidity (RH) ascends. Hygroscopic growth factors (GFs) for 40, 100 and 150 nm alkylaminium sulfate particles do not show an apparent Kelvin effect when RH is less than 45%, whereas GFs of the salt aerosols increase with initial particle size when RH is higher than 45%. Calculation using the Zdanovskii-Stokes-Robinson mixing rule suggests that hygroscopic growth of triethylaminium sulfate-ammonium sulfate mixtures is non-deliquescent, occurring at very low RH, implying that the displacement of ammonia by amine will significantly enhance the hygroscopicity of (NH4)2SO4 aerosols. In addition, light extinction of AAS particles is a combined effect of both scattering and absorption under dry conditions, but is dominated by scattering under wet conditions.

Measurements of nonvolatile size distribution and its link to traffic soot in urban Shanghai

Measurements of particle size distribution and size-resolved particle volatility were conducted using a volatility tandem differential mobility analyzers (V-TDMA) in the urban area of Shanghai during wintertime in January 2014. The nonvolatile mode particles with VSF exceeding 0.85 were always externally mixed with more-volatile mode particles. The average VSF ranged from 0.58 to 0.65 for 100-400nm particles, increasing with the increase of particle size. On average, the nonvolatile mode contributed 15-20% of number fraction for 50-400nm particles. Due to their hydrophobic nature, the nonvolatile particles were not easily removed by wet deposition. The concentrations of the nonvolatile mode particles and NOx were well correlated, indicating that the nonvolatile mode particles were mostly attributed to be fresh traffic soot. The diurnal variations in ensemble VSF and number fraction of nonvolatile mode particles exhibited two peaks in clean days, corresponding to morning and evening rush hours. The VSF distributions of 50nm particles were similar during a transition between haze to clean periods whereas in the accumulation mode range, the number fraction of more-volatile mode and the amount of volatile materials in the more-volatile mode particles during haze periods are considerably larger than those in clean periods, indicating different contribution from transported sources.

Primary Particulate Matter Emitted from Heavy Fuel and Diesel Oil Combustion in a Typical Container Ship: Characteristics and Toxicity

Container ships have been widely recognized as an important emission source within maritime transport. Heavy fuel oil (HFO) and diesel oil (DO) are the two most commonly used fuels. This study reports the characteristics and toxicities of particulate matter (PM) emissions from HFO and DO combustion in a typical container ship. The PM number size distribution possesses a bimodal structure with peaks at ∼20 nm and ∼100 nm. The PM2.5 emission factors (EFs) are 3.15 ± 0.39 and 0.92 ± 0.02 g/kg fuel for HFO and DO, respectively. The benzo[a]pyrene equivalent carcinogenic potency (BaPeq) of 16 polycyclic aromatic hydrocarbons contained in HFO and DO PM2.5 is approximately 0.81 ± 0.10 and 0.12 ± 0.04 mg/kg fuel, respectively. BaPeq concentration shows an increasing tendency with decreased PM size. The reactive oxygen species activity and cytotoxicity of HFO PM2.5 samples are ∼2.1 and ∼2.5 times higher than those of DO PM2.5 samples, respectively. These health risks are both significantly attributed to the BaPeq content in PM2.5 with correlations of 0.86-0.92. Furthermore, the examined biological effects are much greater than those of atmospheric PM2.5 collected in Shanghai. Our results imply that better fuel quality is important for improving air quality and reducing health risks.

Air quality in the middle and lower reaches of the Yangtze River channel: A cruise campaign

Air quality in the middle and lower reaches of the Yangtze River channel: A cruise campaign Zhong Li, Chunlin Li, Xingnan Ye, Hongbo Fu, Lin Wang, Xin Yang, Xinke Wang,Zhuohui Zhao, Haidong Kan, Abdelwahid Mellouki, Jianmin Chen 1 Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Fudan Tyndall Center, Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China

Characteristics of the pollutant emissions in a tunnel of Shanghai on a weekday

Tunnel displays a typical semi-closed environment, and multitudes of the pollutants tend to accumulate. The samples of gaseous pollutants and particulate matter (PM) were collected from the Xiangyin tunnel at Shanghai to investigate the characteristics of the pollutant emissions. The results indicated that both gaseous pollutants and PM exhibited much higher concentrations during the rush hours in the morning and at night due to vehicle emission. Two peaks of the PM concentration were observed in the scope of 0.7-1.1 and 3.3-4.7 μm, accounting for 14.6% and 20.3% of the total concentrations, respectively. Organic matter (OM), EC, and many water-soluble ions were markedly higher at the rush hours in the morning than those at night, implicating comprehensive effects of vehicle types and traffic volume. The particle number concentrations exhibited two peaks at Aitken mode (25 nm and 100 nm) and accumulation mode (600 nm), while the particle volume concentration displayed high values at the accumulation mode (100-500 nm) and coarse mode (2.5-4.0 μm). The peak around 100 nm was detected in the morning rush hours, but it diminished with the decrease of the traffic volume. Individual-particle analysis revealed that main particles in the tunnel were Fe-rich particles, K-rich particles, mineral particles, Ca-S rich particles and Al-Si particles. The particles collected at the rush hours displayed marked different morphologies, element concentrations and particle sizes compared to the ones collected at the non-rush period. The data presented herein could shed a light on the feature of vehicle emissions.