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Throughcontinuous field observation and comprehensive chemicalanalysis, this study quantified the impacts of wildfire emissions,which have occurred repeatedly not only in a long-term period butalso with extensive spatial coverage, on the Himalayan ecosystem. Himalayas and Tibetan Plateau (HTP) is important forglobal biodiversityand regional sustainable development. While numerous studies haverevealed that the ecosystem in this unique and pristine region ischanging, their exact causes are still poorly understood. Here, wepresent a year-round (23 March 2017 to 19 March 2018) ground- andsatellite-based atmospheric observation at the Qomolangma monitoringstation (QOMS, 4276 m a.s.l.). Based on a comprehensive chemical andstable isotope (N-15) analysis of nitrogen compounds andsatellite observations, we provide unequivocal evidence that wildfireemissions in South Asia can come across the Himalayas and threatenthe HTP's ecosystem. Such wildfire episodes, mostly occurringin spring (March-April), not only substantially enhanced theaerosol nitrogen concentration but also altered its composition (i.e.,rendering it more bioavailable). We estimated a nitrogen depositionflux at QOMS of similar to 10 kg N ha(-1) yr(-1), which is approximately twice the lower value of the critical loadrange reported for the Alpine ecosystem. Such adverse impact is particularlyconcerning, given the anticipated increase of wildfire activitiesin the future under climate change.

来源平台：ENVIRONMENTAL SCIENCE & TECHNOLOGY