Role of the Radiative Effect of Black Carbon in Simulated PM_(2.5) Concentrations during a Haze Event in China

The authors quantify the radiative effect of black carbon （BC） on simulated aerosol concentrations during the heavily polluted haze event of 11-14 January 2013 in northern China using the chemistry version of the Weather Research and Forecasting Model （WRF-Chem）. As a result of the stable synoptic conditions, simulated concentrations of BC and PM2.5 averaged over the study period were about 8-16 μg m-3 and 80-100 μg m-3, respectively, in the control simulation （CTRL）. When BC emissions were doubled （2BC）, tripled （3BC）, and quad- rupled （4BC） relative to the CTRL run, the simulated concentrations of aerosols in different regions showed distinct changes. The radiative effect of BC was simulated to increase concentrations of aerosols over Tianjin （Doml） and southern Henan （Dora3）, but to decrease in southern Hebei （Dora2）. Relative to the CTRL simulation, concen- trations of PM2s over Doml, Dom2, and Dom3 were simulated in 4BC to change by ＋18.6 1μg m-3 （＋32.3%）, -5.7 μg m 3 （-7.3%）, and ＋7.2 μg m3 （＋12.6%）, respec- tively. The BC-induced increases in aerosol concentra- tions corresponded mainly to the reductions in planetary boundary layer height over Doml and Dom3. The reduc- tions of aerosol concentrations in Dora2 were mainly caused by the weakened wind convergence at 850 hPa and reduced concentrations of sulfate and nitrate associ- ated with the reduced surface-layer ozone levels and rela- tive humidity.

Black Carbon Instead of Particle Mass Concentration as an Indicator for the Traffic Related Particles in the Brussels Capital Region

The Brussels Capital Region has difficulties in meeting the stringent EU daily limit value for PM10 in all its measuring sites. Postponing the attainment of the deadline was not granted by the EU Commission, mainly due to insufficient judged measures to reduce road traffic emissions. However, a thorough analysis of the data makes clear that neither the particle mass concentration (PM10 and PM2.5) nor the particle number concentration are specific metrics for evaluating the particle pollution originated by traffic. In fact, increased formation of secondary aerosol, together with adverse meteorological conditions and the (re) suspension of the coarser fraction are by far the three main explanations for the numerous PM10 exceeding values. From our experience, amongst the particles measured, only the results for Black Carbon (BC), mainly present in the lower submicron range, are reflective of the direct influence of local traffic. Measured at two traffic sites along with PM mass and number concentrations, the data for Black Carbon show a striking correlation with nitrogen monoxide, a parameter strongly related with the proximity of the local traffic. The correlation factor between Black Carbon data and NO or NOX is much higher than between Black Carbon and the PM mass or number concentration. Therefore the assessment of traffic related particles should consider Black Carbon rather than PM10 or PM2.5.

SPATIAL AND SEASONAL DISTRIBUTIONS OF ATMOSPHERIC CARBONACEOUS AEROSOLS IN PEARL RIVER DELTA REGION, CHINA

Concentrations and spatial distributions of organic carbon (OC) and elemental carbon (EC) in atmospheric particles were measured at 8 sites in four cities (Hong Kong, Guangzhou, Shenzhen and Zhuhai) of Pearl River Delta Region (PRDR), China during 2001 winter period and 2002 summer period. PM2.5 (particie diameter smaller than 2.5 um) and PM10 (particie diameter smaller than 10 um) samples were collected on pre-fired quartz filters with mini-volume samplers and analyzed using thermal optical reflectance (TOR) method. The average PM2.5and PM10 Ievel were 60.1 and 93.1 μg·m-3, respectively, with PM2.5 constituting 65.3% of the PM10 mass. The average OC and EC concentrations in PM2.5 were 12.0 and 5.1 μg·m-3, respectively, while those in PM10 were 16.0 and 6.5 μg·m-3, respectively. The carbo-naceous aerosol accounted for 37.2% of the PM2.5 and 32.8% of the PM10. The highest concentrations of OC and EC were observed at Guangzhou city in both vvinter and summer seasons. The average OC/EC ratios were 2.4 for PM2.5 and 2.5 for PM10, indicating the presence of secondary organic aerosols. The OC and EC in PRDR were found to be strongly correlated (correlation coefficients > 0.6), which implied that similar emission source contribute to the ambient carbon particles.

Chemical composition and source apportionment of PM2.5 and PM2.5-10 in Trombay （Mumbai, India）, a coastal industrial area

PM2.5 and PM2.5 lo concentrations, elemental constituents, and sources in a densely populated coastal industrial area （Trombay, Mumbai） were investigated in 2010 and 2011.The PM2.s and PM2.s lo concentra- tions were 13.50-71.60 and 22.40-127.78 p^g/m3, respectively. The daily PM25 concentrations exceeded the Indian Central Pollution Control Board limit （60 μg/m3） several days in winter. Of the elements analyzed, Si then Al had the highest concentrations in PM2.5- 10, but black carbon then Si had the highest concentrations in PM2.s. The element concentrations varied widely by season. Al, Ca, Fe, Si, and Ti con- centrations were highest in summer, Cl, Mg, and Na concentrations were highest in the monsoon season, and the other trace metal concentrations in both PM2.5 and PM2.5-10 were highest in winter. The PM2.5 and PM2.5-10 sources were apportioned by positive matrix factorization. PM2.5 and PM2.5-10 had six dominant sources, crustal material （8.7% and 25.3%, respectively）, sea salt spray （6.1% and 15.0%, respectively）, coal/biomass combustion （25.5% and 13.8%, respectively）, fuel oil combustion （19.0% and 11.2%, respectively）, road traffic （ 17.7% and 12.6%, respectively）, and the metal industry （ 10.6% and 7.0%, respectively）. Anthropogenic sources clearly contributed most to PM2.5 but natural sources contributed most to PM2.5-10.

上海市大气污染物时间分布特征及影响因子分析

利用2014至2015年上海市监测站数据,对城区大气污染物的特征及影响因子进行分析。结果表明,PM 2.5、PM 10和BC在2015年平均浓度分别为50.90、68.24和2.89μg/m 3,较2014年分别降低了1.90%、4.01%和7.09%。观测期间SO 2、NO、NO 2和O 3的均值分别为17.33、13.15、45.68和70.75μg/m 3。与O 3相反,其他污染物呈典型的冬季高夏季低的特征。PM 2.5、PM 10、BC和NO X浓度都呈早晚双峰模式,与城市机动车尾气排放相关。冬季从西部和西北部的江苏、山东和京津冀地区远距离传输高浓度的PM 2.5颗粒物,在不利的气象条件下大气污染更加严重。