The continuous measurement of nitric oxide (NO), nitrogen dioxide (NO 2) , nitrogen oxides (NO x ) and ozone (O 3 ) was conducted in Tianjin from September 8 to October 15, 2006. The data were used to investigate the relationship between the O 3 distribution and its association with ambient concentrations of NO, NO 2 and NO x (NO and NO 2 ). The measured concentrations of the pollutants in the study area varied as a function of time, while peaks in NO, NO 2 and O 3 all occurred in succession in the daytime. The diurnal cycle of ground-level ozone concentration showed a mid-day peak and lower nighttime concentrations. Furthermore, an inverse relationship was found between O 3 NO, NO 2 and NO x . In addition, a linear relationship between NO 2 and NO x , as well as NO and NO x , and a polynomial relationship between O 3 and NO 2 /NO was found.The variation in the level of oxidant (O 3 and NO 2 ) with NO 2 was also obtained. It can be seen that OX concentration at a given location is made up of two parts: one independent and the other dependent on NO 2 concentration. The independent part can be considered as a regional contribution and is about 20 ppb in Tianjin.An obvious difference in NO, NO x and O 3 concentrations between weekdays and weekends was also found, but this difference did not appear in NO 2 .Lastly, the diurnal variation of O 3 concentration under different meteorological conditions was demonstrated and analyzed.
Background: Rabies is a major public-health problem in developing countries such as China. Although the recent re-emergence of human rabies in China was noted in several epidemiological studies, little attention was paid to the reasons behind this phenomenon paralleling the findings of the previous reports. The purpose of this study is thus first to characterize the current trends of human rabies in China from 1990 to 2007, and then to define better recommendations for improving the postexposure prophylaxis (PEP) schedules delivered to rabies patients.
A severe dust storm (SDS) event occurred during March-20 to March-22, 2010 in China. A regional dynamical model coupled with a dust model (WRF-Dust) is used for analyzing this SDS event. The distribution of API (air pollution index) values in China and satellite (moderate-resolution imaging spectroradiometer-MODIS) AOD (aerosol optical depth) data are used to trace the dust storm and to compare with the model result. Several model sensitive studies are performed to analyze the roles of physical processes (such as dust source, transport, and deposition) in controlling the SDS event. The result suggests that the Gobi Desert is a major dust source of the SDS event. By contrast, the Taklamakan Desert plays minor roles for affecting the high dust concentrations in eastern/southern China during the SDS event. This study also suggests that a large amount of dust particles was deposited at the surface during the transport pathway between the Gobi Desert and eastern/southern China, and the high surface concentrations of dust particles can be considered as a new dust source region, which produced dust air pollution when surface winds were strong. In this study, we define this process as a propagate dust source (PDS). The calculation shows that the calculated dust concentrations were considerably lower than the measured values in the downwind regions of deserts when the PDS process was not included in the model. By including the PDS process, the calculated dust pollution in eastern and southern China is considerably improved. The further detailed analysis shows that the PDS played important roles in controlling the long-range transport of dust particles during the SDS event. This study suggests that this regional dust model (WRF-Dust) is a useful tool to analyze the important processes of dust storms that are often occurred in China.
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