An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed along with a scanning mobility particle sizer (SMPS) and a multi-angle absorption photometer (MAAP) to measure the temporal variations of the mass loading, chemical composition, and size distribution of submicron particulate matter (PM 1 ) in Lanzhou, northwest China, during 11 July-7 August 2012. The average PM 1 mass concentration including non-refractory PM 1 (NR-PM 1 ) measured by HR-ToF-AMS and black carbon (BC) measured by MAAP during this study was 24.5 µg m −3 (ranging from 0.86 to 105 µg m −3 ), with a mean composition consisting of 47 % organics, 16 % sulfate, 12 % BC, 11 % ammonium, 10 % nitrate, and 4 % chloride. Organic aerosol (OA) on average consisted of 70 % carbon, 21 % oxygen, 8 % hydrogen, and 1 % nitrogen, with the average oxygen-to-carbon ratio (O / C) of 0.33 and organic mass-to-carbon ratio (OM / OC) of 1.58. Positive matrix factorization (PMF) of the high-resolution organic mass spectra identified four distinct factors which represent, respectively, two primary OA (POA) emission sources (traffic and food cooking) and two secondary OA (SOA) types -a fresher, semi-volatile oxygenated OA (SV-OOA) and a more aged, low-volatility oxygenated OA (LV-OOA). Trafficrelated hydrocarbon-like OA (HOA) and BC displayed distinct diurnal patterns, both with peak at ∼ 07:00-11:00 (BJT: UTC +8), corresponding to the morning rush hours, while cooking-emission related OA (COA) peaked during three meal periods. The diurnal profiles of sulfate and LV-OOA displayed a broad peak between ∼ 07:00 and 15:00, while those of nitrate, ammonium, and SV-OOA showed a narrower peak between ∼ 08:00-13:00. The later morning and early afternoon maximum in the diurnal profiles of secondary aerosol species was likely caused by downward mixing of pollutants aloft, which were likely produced in the residual layer decoupled from the boundary layer during nighttime. The mass spectrum of SV-OOA was similar to that of coal combustion aerosol and likely influenced by coal combustion activities in Lanzhou during summer. The sources of BC were estimated by a linear decomposition algorithm that uses the time series of the NR-PM 1 components. Our results indicate that a main source of BC was local traffic (47 %) and that transport of regionally processed air masses also contributed significantly to BC observed in Lanzhou. Finally, the concentration and source of polycyclic aromatic hydrocarbons (PAHs) were evaluated.

Abstract. An 1.5-level-closure and 3-D non-stationary atmospheric boundary layer (ABL) model and a radiation transfer model with the output of Weather Research and Forecast (WRF) Model and lidar AML-1 are employed to simulate the dust aerosol radiative effect and its influence on ABL in Beijing for the period of 23–26 January 2002 when a dust storm occurred. The simulation shows that daytime dust aerosol radiative effect heats up the ABL at the mean rate of about 0.68 K/h. The horizontal wind speed from ground to 900 m layer is also overall increased, and the value changes about 0.01 m/s at 14:00 LT near the ground. At night, the dust aerosol radiative effect cools the ABL at the mean rate of −0.21 K/h and the wind speed lowers down at about −0.19 m/s at 02:00 LT near the ground.

Monolayers of a new series of amide‐containing alkanethiol compounds, CH3(CH2)n‐2C(O)NHC2H4SH (referred as CnC2SH, n=4, 5, 5, 8), were self‐assembled from ethanol solutions onto gold and their structures have been characterized using the reflectance absorption infrared spectroscopy (RA‐FTIR) and wettability measurement. It has been proved that the CO and N‐H bonds are parallel to the gold surface and the orientations of alkyl chain in these Self‐Assembled Monolayers (SAMs) are perpendicular to the surface. The special orientation of the amide moiety and molecular axis are suggested to be attributed to the hydrogen‐bonding formed between the amide moieties of neighbor molecules. Meanwhile, wettability measurement reveals that the packing degree of the SAMs depends on the length of the alkyl chains in the thiol molecules. These results demonstrate that both the hydrogen‐bonding and the length of the alkyl chain exerts the tremendous influnece on the orientation of amide‐containing alkanethiol molecules. And also, it give us a way to control the molecular orientation in SAMs in molecular level.

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