Carbonaceous aerosols on the south edge of the Tibetan Plateau: concentrations, seasonality and sources
Carbonaceous aerosols on the south edge of the Tibetan Plateau: concentrations, seasonality and sources
复制标题
青藏高原南缘碳质气溶胶：浓度、季节和来源
DOI：
10.5194/acp-15-1573-2015
复制
发表时间：
2015-01-01
影响因子：
6.3
通讯作者：
Fu, P.
中科院分区：
文献类型：
--
作者：
Cong, Z.;Kang, S.;Fu, P.
抽象的。为了定量评估碳质气溶胶对青藏高原南缘的影响，2009年8月至2010年7月，珠穆朗玛峰大气与环境观测研究站（QOMS，28.36° N，86.95° E，4276 m a.s.l.）每周采集气溶胶样品。有机碳（OC）、元素碳（EC）和水溶性有机碳的平均浓度分别为1.43、0.25和0.77 μg m−3。 QOMS 的 OC 和 EC 浓度水平与喜马拉雅山南坡高海拔地点（位于金字塔的朗塘和尼泊尔气候观测站，或 NCO-P）相当，但比印度马诺拉峰和尼泊尔戈达瓦里的浓度低 3 至 6 倍。硫酸盐是最丰富的阴离子种类，其次是硝酸盐，分别占总离子质量的 25% 和 12%。 Ca2+ 是最丰富的阳离子物种（年平均值为 0.88 μg m−3）。以Ca2+浓度表示的粉尘负荷全年相对稳定。 OC、EC和其他离子物种（NH4+、K+、NO3−和SO42−）在季风前时期表现出明显的峰值，在季风季节表现出最低值，这与之前报道的喜马拉雅山南坡气溶胶成分（如Langtang和NCO-P）的季节趋势相似。 QOMS 气溶胶中的 OC 和 EC 与 K+ 和左旋葡聚糖的强相关性表明它们主要来源于生物质燃烧。 MODIS观测到的火点和向后的气团轨迹进一步表明，在季风季节前，印度北部和尼泊尔的农业和森林火灾最有可能是QOMS碳质气溶胶的来源。此外，CALIOP 的观测证实，空气污染羽流在此期间穿过喜马拉雅山。 QOMS 和 NCO-P 之间日气溶胶光学深度（500 nm）的高度相干变化表明喜马拉雅山的两个斜坡具有共同的大气环境状况。除了大范围的大气环流外，独特的山谷风系统也对空气污染物输送产生重要影响。
Abstract. To quantitatively evaluate the effect of carbonaceous aerosols on the south edge of the Tibetan Plateau, aerosol samples were collected weekly from August 2009 to July 2010 at Qomolangma (Mt. Everest) Station for Atmospheric and Environmental Observation and Research (QOMS, 28.36° N, 86.95° E, 4276 m a.s.l.). The average concentrations of organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon were 1.43, 0.25 and 0.77 μg m−3, respectively. The concentration levels of OC and EC at QOMS are comparable to those at high-elevation sites on the southern slopes of the Himalayas (Langtang and Nepal Climate Observatory at Pyramid, or NCO-P), but 3 to 6 times lower than those at Manora Peak, India, and Godavari, Nepal. Sulfate was the most abundant anion species followed by nitrate, accounting for 25 and 12% of total ionic mass, respectively. Ca2+ was the most abundant cation species (annual average of 0.88 μg m−3). The dust loading, represented by Ca2+ concentration, was relatively constant throughout the year. OC, EC and other ionic species (NH4+, K+, NO3− and SO42−) exhibited a pronounced peak in the pre-monsoon period and a minimum in the monsoon season, being similar to the seasonal trends of aerosol composition reported previously from the southern slope of the Himalayas, such as Langtang and NCO-P. The strong correlation of OC and EC in QOMS aerosols with K+ and levoglucosan indicates that they mainly originated from biomass burning. The fire spots observed by MODIS and backward air-mass trajectories further demonstrate that in pre-monsoon season, agricultural and forest fires in northern India and Nepal were most likely sources of carbonaceous aerosol at QOMS. Moreover, the CALIOP observations confirmed that air-pollution plumes crossed the Himalayas during this period. The highly coherent variation of daily aerosol optical depth (500 nm) between QOMS and NCO-P indicates that both slopes of the Himalayas share a common atmospheric environment regime. In addition to large-scale atmospheric circulation, the unique mountain/valley breeze system can also have an important effect on air-pollutant transport.