Beijing has for many years suffered from serious air pollution. The Chinese capital's latest smog alert has dragged on into the first week of
2017.
In fact, the joint prevention and control policy for atmospheric
pollution in the Beijing-Tianjin-Hebei region was announced after the
heavy haze event occurred on 1 January 2013. But it is still uncertain
about what or where to control and prevent in detail.
‘Pre-warning should be implemented, and the regional stationary emissions should be controlled and reduced in advance. Once the pollution formed, the local emissions should be controlled, thus the peak values of contaminant can be efficiently restrained.’
The research group led by WANG Yuesi from the Institute of
Atmospheric Physics (IAP) has monitored the evolution of regional
atmospheric mixing layer height (MLH) and attenuated backscattering
coefficient in the Beijing-Tianjin-Hebei region for years. Combined with
the particle's chemical component online analysis, some highlighted
results about the regional heavy haze formation mechanism are obtained.
"Beijing is located to the north of the North China Plain. During the
initial polluted period, it is affected by southerly transport at the
latitude of 500-1000 m." WANG find, "Once the pollution is formed, the
MLH will decrease quickly to 500m even lower and increase the pollutant
concentration rapidly with compression mechanism. Meanwhile, the
hygroscopic growth and heterogeneous chemical processes enhancement
under the circumstance of high relative humidity will facilitate the
explosive growth of secondary particulate matters."
The co-existence of those factors can further exacerbate the
pollution degree. At this time, although the impact of regional
transport is less important, the local emitted (such as motor vehicles)
pollutants are unable to diffuse, thus will result in a consistent
increase of the pollutant concentrations in the MLH.
The heavy haze formation in Beijing is therefore depicted as
"initiate by the regional transport mainly from the coal burning in
surrounding areas, and intensified by the local secondary formation
originated from the motor vehicles". This conclusion is presented in
papers written by TANG Guiqian, LIU Zirui, WANG Lili, HU Bo, XIN Jinyuan
and ZHU Xiaowan and is confirmed consistently by some new experimental
researches.
According to these researches, suggestions are proposed to the
environmental protection administration: Pre-warning should be
implemented two or three days ahead of the heavy haze coming, and the
regional stationary emissions especially the elevated sources should be
controlled and reduced in advance. Once the pollution formed, the local
emissions should be controlled, thus the peak values of contaminant can
be efficiently restrained.
Source: Eurekalert
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