Aerosol particles at a high‐altitude site on the Southeast Tibetan Plateau, China: Implications for pollution transport from South Asia

Abstract

at Lulang, a high-altitude (>3300m above sea level) site on the southeast Tibetan Plateau (TP); objectives were to determine chemical characteristics of the aerosol and identify its major sources. We report aerosol (total suspended particulate, TSP) mass levels and the concentrations of selected elements, carbonaceous species, and water-soluble inorganic ions. Significant buildup of aerosol mass and chemical species (organic carbon, element carbon, nitrate, and sulfate) occurred during the premonsoon, while lower concentrations were observed during the monsoon. Seasonal variations in aerosol and chemical species were driven by precipitation scavenging and atmospheric circulation. Two kinds of high-aerosol episodes were observed: one was enriched with dust indicators (Fe and Ca , and Fe. The TSP loadings during the latter were 3 to 6 times those on normal days. The greatest aerosol optical depths (National Centers for Environmental Protection/National Center for Atmospheric Research reanalysis) occurred upwind, in eastern India and Bangladesh, and trajectory analysis indicates that air pollutants were transported from the southwest. Northwesterly winds brought high levels of natural emissions (Fe, Ca 2+ ) and low levels of pollutants (SO 4 2À , NO 3 À , K + , and EC); this was consistent with high aerosol optical depths over the western deserts and Gobi. Our work provides evidence that both geological and pollution aerosols from surrounding regions impact the aerosol population of the TP.

Seasonal Variation, Sources and Transport of Aerosols at Lijiang, Southeast Tibetan Plateau

“…4). This supports the findings of other studies in Lijiang and the south TP (Zhang et al, 2011, Zhao et al, 2013.…”

“…However, the greatest concentration of NO 3 -was observed during the pre-monsoon period and that of SO 4 2-and NH 4 + during the monsoon period, which indicates that there are additional sources of NO 3 -during the pre-monsoon period and SO 4 2-and NH 4 + during the monsoon period, respectively. Previous studies have shown that the largest total ionic concentration occurred during the pre-monsoon period at other sites along the south edge of the TP (Shrestha et al, 2000;Desesari et al, 2010;Zhao et al, 2013). However, our data shows that the largest total detected ionic concentration was observed during monsoon period, which was caused by the large concentrations of SO 4 2-and NH 4 + during this period (Table 2).…”

“…Therefore the plateau has been frequently chosen as an ideal location to observe the atmospheric environment and to evaluate various impacts of human activities (Kang et al, 2002;Cong et al, 2007) and several aerosol particle studies have been conducted over the TP region (Wake et al, 1994;Cong et al, 2007;Ming et al, 2007;Cao et al, 2009;Wu et al, 2009;Yang et al, 2009;Zhang et al, 2010Zhang et al, , 2012aZhao et al, 2013;Zhang et al, 2014). For studies aiming to investigate the influences on regional climate change, water resources and glacier retreat by polluted aerosols from south Asia, considerable attention has been focused on the south slope of the TP (Hindman and Upadhyay, 2002;Ramanathan et al, 2007;Bonasoni et al, 2008Bonasoni et al, , 2010Decesari et al, 2010).…”

Atmospheric Aerosol Elements over the Inland Tibetan Plateau: Concentration, Seasonality, and Transport

“…Pollutants may reach higher elevations or move farther to the inland TP through long-range transport (Ming et al, 2010;Xia et al, 2011;Zhao et al, 2013;Lüthi et al, 2015). In addition, air masses are transported from South Asia year-round (Fig.…”

“…Most aerosol chemistry investigations in the TP were short-term and conducted at the edge of the plateau (e.g., Wen et al, 2001;Cong et al, 2007;Meng et al, 2013;Zhao et al, 2013) and Lhasa, the capital city of the Tibet Autonomous Region of China (Zhang et al, 2000;Cong et al, 2011). Therefore, considering the vast area of the TP and the very limited data available for the region, more investigations are required to understand the aerosol chemical composition over the TP, particularly in the remote and inland TP.…”