Changes in chemical components of aerosol particles in different haze regions in China from 2006 to 2013 and contribution of meteorological factors

摘要

Since there have been individual reports of persistent haze–fog events in January 2013 incentral-eastern China, questions on factors causing the drastic differences inchanges in 2013 from changes in adjacent years have been raised. Changes inmajor chemical components of aerosol particles over the years also remainunclear. The extent of meteorological factors contributing to such changes isyet to be determined. The study intends to present the changes indaily based major water-soluble constituents, carbonaceous species, andmineral aerosol in PM at 13 stations within different haze regions inChina from 2006 to 2013, which are associated with specific meteorological conditionsthat are highly related to aerosol pollution (parameterized as an indexcalled Parameter LinkingAerosol Pollution and Meteorological Elements – PLAM). No obvious changes were found in annual meanconcentrations of these various chemical components and PM in 2013,relative to 2012. By contrast, wintertime mass of these components wasquite different. In Hua Bei Plain (HBP), sulfate, organic carbon (OC), nitrate, ammonium, element carbon (EC),and mineral dust concentrations in winter were approximately 43, 55, 28, 23, 21, and 130 μg m, respectively; these masses wereapproximately 2 to 4 times higher than those in background mass, which alsoexhibited a decline during 2006 to 2010 and then a rise till 2013. Themass of these concentrations and PM, except minerals, respectively,increased by approximately 28 to 117 % and 25 % in January 2013compared with that in January 2012. Thus, persistent haze–fog eventsoccurred in January 2013, and approximately 60 % of this increase incomponent concentrations from 2012 to 2013 can be attributed to severemeteorological conditions in the winter of 2013. In the Yangtze River Delta (YRD) area, winter masses of these components, unlike HBP, have notsignificantly increase since 2010; PLAM were also maintained at a similarlevel without significant changes. In the Pearl River Delta (PRD) area, theregional background concentrations of the major chemical components weresimilar to those in the YRD, accounting for approximately 60–80 % of those in HBP.Since 2010, a decline has been found for winter concentrations, which can bepartially attributable to persistently improving meteorological conditionsand emission cutting with an emphasis on coal combustion in this area.In addition to the scattered and centralized coal combustion for heating,burning biomass fuels contributed to the large increase in concentrations ofcarbonaceous aerosol in major haze regions in winter, except in the PRD. Noobvious changes were found for the proportions of each chemical components ofPM from 2006 to 2013. Among all of the emissions recorded in chemicalcompositions in 2013, coal combustion was still the largest anthropogenicsource of aerosol pollution in various areas in China, with a higher sulfateproportion of PM in most areas of China, and OC was normally rankedthird. PM concentrations increased by approximately 25 % inJanuary of 2013 relative to 2012, which caused persistent haze–fog events inHBP; emissions also reduced by approximately 35 % in Beijing and itsvicinity (BIV) in late autumn of 2014, thereby producing the Asia PacificEconomic Cooperation (APEC) blue (extremely good air quality); thus, one canexpect that the persistent haze–fog events would be reduced significantly inthe BIV, if approx. one-third of the 2013 winter emissions were reduced,which can also be viewed as the upper limit of atmospheric aerosol pollutioncapacity in this area.