[Source Apportionment and Optical Properties of Fine Particles Associated with Regional Pollution in the Yangtze River Delta].

In order to study the distribution and optical characteristics of fine particulate matter pollution in the Yangtze River Delta, PM2.5 samples were collected and analyzed from city (Suzhou), suburb (Nanjing), and regional background monitoring stations (Lin'an). The average concentrations of PM2.5 in Suzhou, Nanjing, and Lin'an were (169.8±56.5), (169.9±51.2), and (154.0±54.9) µg·m-3, respectively. There was little difference in meteorological conditions and the chemical composition of PM2.5 among the three sites, and PM2.5 pollution showed significant synchronization and regionalization characteristics. The extinction coefficients estimated using a chemical component method for Suzhou, Nanjing, and Lin'an are (561±223), (655±340), and (679±349) Mm-1, respectively. There is strong correlation between the extinction coefficients estimated by the chemical component method and those estimated by a visibility-based method (r 0.73-0.80). Using a PMF model to analyze the PM2.5 sources, secondary nitrate sources (32%) and secondary sulfate sources (25%) accounted for the largest proportions followed by biomass combustion (16%), incomplete combustion (7%), fuel combustion (7%), soil crusts (8%), and marine sources (5%). The primary sources of the extinction coefficients of PM2.5 are secondary nitrate and sulfate sources, incomplete combustion, and biomass combustion. Compared with the source contribution of mass concentrations, the proportion of secondary nitrate and sulfate sources decreased by approximately 4% and the proportion of the incomplete combustion source increased by 5%. These results show that there are differences in the contributions of various PM2.5 source according to mass concentrations and extinction coefficients.

[Modeling Study of A Typical Summer Ozone Pollution Event over Yangtze River Delta].

WRF/Chem model was used to analyze the temporal and spatial distribution characteristics and physical and chemical mechanism of a typical summer ozone pollution event over Yangtze River Delta (YRD). The result showed that the model was capable of reproducing the temporal and spatial distribution and evolution characteristics of the typical summer ozone pollution event over YRD. The YRD region was mainly affected by the subtropical high-pressure control, and the weather conditions of sunshine, high temperature and small wind were favorable for the formation of photochemical pollution on August 10-18, 2013. The results of simulation showed that the spatial and temporal distribution of O3 was obviously affected by the meteorological fields, geographic location, regional transport and chemical formation over YRD. The sensitivity experiment showed that the O3 concentration affected by maritime airstream was low in Shanghai, but the impact of Shanghai emissions on the spatial and temporal distribution of O3 concentration over YRD was significant; The main contribution of the high concentration of O3 in Nanjing surface was chemical generation ( alkene and aromatic) and the vertical transport from high-altitude O3, whereas the main contribution of the high concentration of O3 in Hangzhou and Suzhou was physics process. The influence of the 15:00 peak concentration of O3 over YRD was very obvious when O3 precursor was reduced at the maximum O3 formation rate (11-13 h).

[Analysis of the impact of two typical air pollution events on the air quality of Nanjing].

Nanjing and the surrounding area have experienced two consecutive serious air pollution events from late October to early November in 2009. The first event was long-lasting haze pollution, and the second event was resulted from the mixed impact of crop residue burning and local transportation. The effects of regional transport and local sources on the two events were discussed by cluster analysis, using surface meteorological observations, air pollution index, satellite remote sensing of fire hot spots data and back trajectory model. The results showed that the accumulation-mode aerosol number concentrations were higher than those of any other aerosol modes in the two pollution processes. The peak value of aerosol particle number concentrations shifted to large particle size compare with the previous studies in this area. The ratio of SO4(2-)/NO3(-) was 1.30 and 0.99, indicating that stationary sources were more important than traffic sources in the first event and the reverse in the second event. Affected by the local sources from east and south, the particle counts below 0.1 microm gradually accumulated in the first event. The second event was mainly affected by a short-distance transport from northeast and local sources from southwest, especially south, the concentration of aerosol particles was higher than those in other directions, indicating that the sources of crop residue burning were mainly in this direction.

[Atmospheric particle formation events in Nanjing during summer 2010].

Feature of aerosol particle number concentration, condition and impact factor of new particle formation (NPF) were investigated in Nanjing during summer. In this study, aerosol particle number concentration and gaseous pollutants (O3, SO2 and NO2) measurements were carried out by Wide-Range Particle Spectrometer (WPS) and Differential Optical Absorption Spectroscopy (DOAS) in July 2010. Combining with observations from Automatic Weather Station and Backward Trajectory Simulation, the condition and impact factor of NPF were discussed. Results showed that the averaged 10-500 nm particle number concentration was 1.7 x 10(4) cm(-3), similar to some typical observation values in North American and Europe; the 10-25 nm particle number concentration accounted for 25% of the total number concentration. Six NPF events occurred during observation. We analyzed that stable wind speed and direction, strong solar radiation promoted the NPF. The humidity during NPF event varied from 50% to 70%. Results indicated that clean ocean air mass brought from easterly and southerly wind promoted the NPF by Backward Trajectory Model Simulation. During the NPF event, the 10 - 25 nm particle number concentration positively correlated with the concentration of SO2, and negatively correlated with O3, whereas poorly correlated with NO2.