资源环境科技发展态势分析平台

The increase in anthropogenic emissions and associated climate change have become a growing critical environmental concern, with significant implications for human health and ecological security. The rapid economic growth in South Asia has contributed additional stress on the atmospheric environment in the surrounding regions. Earlier ice core chemical studies revealed a strong atmospheric transport to the Himalayan region from South Asia through the Indian summer monsoon. Continuous observation of atmosphere chemistry is not yet available, while ice core chemical record from high mountain regions can serve as an alternative proxy. So far, the influence of these transports on the southern Tibetan Plateau has not been adequately evaluated as only a few glaciochemical records are rebuilt. Here, we present a chemical record from a shallow ice core (with depth of 21.4 m), which was retrieved from the Qiangyong Glacier in the rain-shadow area of the Himalayas drilled in 2009 and dated back to the past 23 years of 1987-2009. The primary objective was to retrieve glaciochemical record and establish possible sources of soluble components, in particular those of NH4+. Empirical orthogonal function (EOF) analysis on the eight major ions series (Ca2+, Na+, Mg2+, NH4+, K+, Cl-, NO3-, So(4)(2-)) from this core reveals that NH4+ is loaded primarily separately on EOF3, likely suggesting a specific source out of the other ion signals. Both a back-trajectory model and the correlation analysis between NH4+ and So(4)(2-) indicate the anthropogenic origin from South Asia. Although earlier ice core records showed a curbed increasing trend in NH4+, our new data reveals that the increasing trend continued after 1980 and experienced a rapid increase after 2000. This trend is in accordance with the increasing population and agriculture activities in South Asia, corresponding with increasing anthropogenic emission. Spatial comparison of the Qiangyong ice core record with existing NH4+ records from other ice cores in the Tibetan Plateau show that concentrations of NH4+ are regionally increasing. However, the relatively small rise in Qiangyong record is probably in association with the effective transportation barrier of the Himalayas. This study advances the knowledge of atmospheric environmental change in the northern Himalayas and the air mass transport of anthropogenic pollutants from South Asia to the southern Tibetan Plateau via the summer Indian monsoon.