The paper analyzes air quality data of Hangzhou urban area from 2002 to 2006 , the results show that the Premier pollutant is PM10 in Hangzhou urban area. There are signifificant seasonal variations and " bimodal type " daily varietions of PM10 and PM2.5 . Ihe study of relationship between PM10 concentration and weather system indicate that the peak concentration pollution is easily appeared under the high_pressure control system, and PM10 concentration is relatively lower under the easterly system . The weather phenomenon as the haze and mist exist tremendous influence to PM2.5 and PM10 under a long-time stable weather condition.
Sulfate is a major component of PM10 in atmosphere and its concentration is affected by many factors. In this article, sulfate concentration and sulfur oxidation ratio in heating season were measured with on-line systems, and the relationships between sulfur oxidation ratio and influencing factors were discussed.
The results showed that the most abundant component of PM10 was sulfate and there was a significant correlation between sulfate and SO2 during heating season in Beijing. Coal burning was still the primary pollution source in heating season. During non-pollution period, SO42- was mainly from aged air mass with high sulfur oxidation ratio which was promoted by O3 during long range transportation. During pollution period, SO42- was mainly from original source with lower sulfur oxidation ratio which had no obvious correlation with O3. Execpt wind speed, there were no significant correlations bwteen meterological facotrs and sulfate and between meteorological factors and sulfur oxidation ratio during observation.
The northwestern Chinese deserts, with Taklimakan Desert as its main body, is one of important sources of the Asian airborne dust. Using the NCAR Community Climate Model (CCM3) coupled with a mineral Dust Entrainment and Deposition model (DEAD), we study effects of land-cover change in desert regions of northwestern China on the airborne dust over East Asia. The emission and contribution of the northwestern deserts to the Asian airborne dust are simulated and analyzed through two groups of numerical experiments with changed land-cover types in desert and semi-desert regions of the northwestern China. The main results can be concluded as the following: The dust emission and airborne dust are closely related to land-cover conditions. Land melioration, such as a change in the land surface type from desert or semi-desert to grassland, restrains the dust emission significantly. The influence of the northwestern deserts on the airborne dust is usually overcastted to the northern China and even to Mongolia. Without Taklimakan Desert, the total emission and deposition fluxes would decrease by up to 50% over the northern China. The emission fluxes of the second and third diameters (1.0-2.5 μm and 2.5-5.0 μm), which account for 76% of the total emission flux, significantly decrease in the no-desert experiment. The dust from the northwestern desert and semi-desert regions can influence the air quality of North China and Northeast China, and even Japan and Korea, through the transport of the atmospheric general circulation.
The investigation of PM2.5 aerosols using a portable mini-volume sampler was conducted between May 22 and September 22, 2006, in high-tech zone, Xi’an. Meantime NH3 gases were also sampled using passive Ogawa sampler. Water soluble ions (WSI) and NH3 concentrations were analyzed using an ion chromatogram (IC) analyzer. Integrating these data with SO2 and NO2 concentrations, the characteristics and sources of WSI of PM2.5 in spring and summer in Xi’an were studied. The results indicated that WSI in spring and summer was mainly composed of SO42-, NO3- and NH4+, accounting for 21.68%, 7.52% and 5.62% in mass, respectively, and the PM2.5 in spring and summer in XI’an were generally acidic. SO2 concentrations were poorly correlated with SO42-, NO3- and NO2, indicating that sulfate, nitrite, and ammonium in Xi’an are of different origins.
Based on the data of aerosol chemical compositions obtained at WMO GAW (World Meteorological Organization Global Atmospheric Watch) station in eastern China－Lin’An regional background air pollution monitoring station, two methods (referred as Malm method and Stelson method) that were described by Malm (Malm et al.,1994) and Stelson (Stelson and Seinfeld, 1981) were used to study the mass closure (or mass reconstruction) of sampled aerosols. The inter-comparison of reconstructed aerosol masses with the gravimetric masses showed good agreements, although the two methods used different chemical composition species. The mass closure indicated that both methods could identify most of aerosol masses sampled during the experiment. This study suggested that based on the interests or objectives of the specific study, both of the Malm method and the Stelson method could be used for the aerosol mass closure.