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.

A haze episode occurred on 12 September 2009 in Shanghai, when the mass ratio of PM 1.0 /PM 2.5 (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 (NH 4 ) 2 SO 4 and NH 4 NO 3 to the haze episode. The molar ratio of) rose up to 0.96, coincident with the large increase in NH 3 concentration, suggesting that the available NH 3 played a vital role in the enhancement of particulate sulfate and nitrate during the haze episode.

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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.

The effectiveness of several zeolite catalysts was investigated using the cataluminescence (CTL) gas sensor system. Trace amounts of n-hexane in air samples were detected by this method. This research establishes that the specific pore size of the zeolite offers designable environment for selective CTL reaction, and "Lewis-type" basic sites appear to contribute to the catalytic nature of the zeolite surface. By incorporating either Cs+ or K+, the velocity and luminescence intensity of these catalytic reactions increase while going from Na to Cs, according to the basic nature of this group of cations in the following order: Cs > K > Na. The proposed sensor shows high sensitivity and selectivity to n-hexane at a mild reaction temperature of 225 degrees C. Quantitative analysis was performed at a selected wavelength of 460 nm. The linear range of CTL intensity versus concentration of n-hexane was 0.776-23.28 microg/mL (R = 0.997, n = 7) on CsNaY, and 0.776-23.28 microg/mL (R = 0.998, n = 7) on CsNaX, with a detection limit of 0.155 microg/mL (signal-to-noise ratio 3). Interferences from foreign substances such as methanol, ethanol, 2-propanol, acetone, acetonitrile, chloroform, or dichlormethane and other alkanes, aromatics, and alkyl aromatics such as methane, n-pentane, 3-methylpentane, 3,3-dimethylpentane, methylbenzene, ethylbenzene, and sec-butylbenzene were very low or not detectable. Results of a series of GC and GC/MS experiments suggest that the possible mechanism of the reaction is the formation of an unstable transition structure with a four-member ring, and this ring most probably consists of an oxygen atom and a carbonium ion localized on the zeolite suface.

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The hygroscopic properties of inorganic salt particles, including (NH 4 ) 2 SO 4 , NaCl, Na 2 SO 4 and NaNO 3 , are investigated using a self-assembled hygroscopic tandem differential mobility analyzer (H-TDMA) system. The iso-GF (growth factor) curves are derived to illustrate the effects of the initial particle size (D 0 ) and relative humidity (RH) on the GFs. For those salt particles of 100 nm, the GFs measured agreed well with their theoretical Köhler curves. In the size range of 20-200 nm, the GFs of (NH 4 ) 2 SO 4 , NaCl and Na 2 SO 4 particles all continuously decrease with D 0 increasing below the deliquescence RH (DRH). However, when RH is higher than the DRH, the GFs of those salts aerosols increase with D 0 throughout the investigated size range. Similar increase trend of GFs with D 0 is also observed for NaNO 3 aerosols though they do not exhibit the abrupt deliquescence behavior. From iso-GF curves, it can be clearly observed that the GFs of (NH 4 ) 2 SO4, NaCl and Na 2 SO 4 particles all increase with the RH while the values decrease with D 0 below DRH. And above DRH, the GFs are more sensitive to D 0 for particles smaller than 60 nm, while the GFs are more sensitive to RH for particles larger than 80 nm. For NaNO 3 aerosols, the iso-GF curves indicate the size-effect becomes more prominent on their hygroscopicity as the RH increases. The iso-GF curves provide a lucid and explicit insight into the hygroscopic growth of salts particles. Through iso-GF curves, we can clearly elucidate the major factor that affects the ultimate particle diameter at ambient atmosphere.

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 PM 2.5 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 (BaP eq ) of 16 polycyclic aromatic hydrocarbons contained in HFO and DO PM 2.5 is approximately 0.81 ± 0.10 and 0.12 ± 0.04 mg/kg fuel, respectively. BaP eq concentration shows an increasing tendency with decreased PM size. The reactive oxygen species activity and cytotoxicity of HFO PM 2.5 samples are ∼2.1 and ∼2.5 times higher than those of DO PM 2.5 samples, respectively. These health risks are both significantly attributed to the BaP eq content in PM 2.5 with correlations of 0.86−0.92. Furthermore, the examined biological effects are much greater than those of atmospheric PM 2.5 collected in Shanghai. Our results imply that better fuel quality is important for improving air quality and reducing health risks.