喜马拉雅珠峰地区冬季大气气溶胶化学组分及光学特征

为了研究喜马拉雅山北坡冬季大气气溶胶化学组分、光学特征及来源,2017年11—12月在珠穆朗玛峰站(QOMS)共采集22个PM2.5样品.结果显示:PM2.5中包括水溶性离子(WSIs)、有机质(OM)、元素碳(EC)在内的所有检测成分,总质量浓度为(3.36±1.06)μg·m-3;有机碳(OC)、元素碳(EC)和水...

Chemical composition and optical properties of the atmospheric aerosols during wintertime in the Mount Qomolangma region,the Himalayas

To study the chemical composition， optical characteristics and sources of atmospheric aerosols on the north slopes of the Himalayas （the south edge of the Tibetan Plateau）， 22 samples were collected daily from November 2017 to December 2017 at Qomolangma Station for Atmospheric and Environmental Observation and Research （QOMS， 28.36° N， 86.95° E， 4 276 m a.s.l.）. The total mass concentrations of identified species （WSIs+OM+EC） were （3.36±1.06） μg?m^-3. The average concentrations of organic carbon （OC）， elemental carbon （EC） and water-soluble organic carbon were （1.10±0.38） μg?m^-3， （0.13±0.12） μg?m^-3 and （0.84±0.24） μg?m^-3， respectively， lower than that in pre-monsoon. The carbonaceous matter （OM+EC） was the dominated contributor， accounting for 73.6%， which was similar to the previous research. Absorption coefficient at 365 nm （Abs₃₆₅） of PM_2.5 water-soluble components， typically used as a proxy for water-soluble brown carbon （WS-BrC）， correlated well with the WSOC and K⁺ concentration （R²=0.63， 0.50）， but weak correlation with EC （R²=0.01）， indicates that they probably originated from biomass burning and secondary formations. The values of AAE and MAE of the water extract of PM_2.5 were （4.60±1.47）， （0.45±0.13） m²?g^-1， respectively. Moreover， the fire spots observed by MODIS and backward air-mass trajectories further demonstrated that in winter， fires in Nepal were most likely sources of carbonaceous aerosol at QOMS. Meanwhile， the unique local wind field on the Himalayas was an important channel for air-pollutant transport.