Long-term trends in visibility and impacts of aerosol composition on visibility impairment in Baoji, China

Visibility impairment has become an important environmental issue receiving great attention from both the scientific community and the public. Long-term meteorological data from Baoji, China, were collected to investigate the trend in visibility change from 1980 to 2012. The 33-year average visual r...

Full description

Saved in:
Bibliographic Details
Published in:Atmospheric research 2014-11, Vol.149, p.88-95
Main Authors: Xiao, S., Wang, Q.Y., Cao, J.J., Huang, R.-J., Chen, W.D., Han, Y.M., Xu, H.M., Liu, S.X., Zhou, Y.Q., Wang, P., Zhang, J.Q., Zhan, C.L.
Format: Article
Language:English
Subjects:
Applied sciences
Atmospheric pollution
Earth, ocean, space
Exact sciences and technology
External geophysics
Light extinction coefficient
Meteorology
Particles and aerosols
PM2.5 chemical composition
Pollutants physicochemistry study: properties, effects, reactions, transport and distribution
Pollution
Source apportionment
Visibility trend
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Visibility impairment has become an important environmental issue receiving great attention from both the scientific community and the public. Long-term meteorological data from Baoji, China, were collected to investigate the trend in visibility change from 1980 to 2012. The 33-year average visual range is 12.0km. The best 20% of the visibility observations in a calendar year shows a general decreasing trend from 1994 onwards, while the worst 20% exhibits a slight increasing trend from 1997 onwards. These results suggest the progressive degradation of air quality in Baoji in recent years. Intensive PM2.5 measurements were conducted from March 2012 to February 2013 to determine the causes of visibility impairment. An analysis based on IMPROVE equation reveals that PM2.5 organic matter (OM) contributes to 34.2% of the light extinction coefficient (bext) on an annual basis, followed by (NH4)2SO4 (30.0%), NH4NO3 (20.1%), elemental carbon (9.2%) and soil dust (6.5%). The largest contributor to bext for the Worst 20% group is (NH4)2SO4, and the contribution of NH4NO3 for the Worst 20% group increases by a factor of ~3 compared with the Best 20% group. Source apportionment using a positive matrix factorization receptor model indicates that secondary sulfate is the main source of PM2.5 (23.0%), followed by fugitive dust (20.5%), coal combustion (19.9%), secondary nitrate (15.5%), biomass burning (14.3%) and motor vehicle emissions (6.8%). These quantitative results could be useful for policy makers to take effective measures to control the haze pollution in Baoji. Further, the results also are likely to be relevant for other mid-sized cities in China. •The 33-year average visual range is 12.0km.•(NH4)2SO4 is the largest contributor to bext for the worst 20% group.•Secondary sulfate, fugitive dust and coal combustion are the main sources of PM2.5.
ISSN:0169-8095
1873-2895
DOI:10.1016/j.atmosres.2014.06.006