Variability of Levoglucosan in Precipitation in Lhasa as a Proxy for Tracing Vegetation Fires

Abstract

Levoglucosan has been extensively used as a biomarker for tracing vegetation fire emissions in atmospheric aerosols, ice cores, and lake sediments. Precipitation can scavenge levoglucosan from the atmosphere to the Earth’s surface. However, almost no previous research has investigated the variability of levoglucosan in precipitation. This research reports levoglucosan records in precipitation samples collected from March 2018 to September 2019 in Lhasa, on the southern Tibetan Plateau. Although the event-based levoglucosan variations seem random, the variability on monthly or seasonal time scales is highly correlated to vegetation fire changes along the Himalayas and surrounding regions. In addition, extreme wildfires in southern Central Asia also affect levoglucosan records in precipitation at Lhasa, especially during the summer. Our results indicate that local vegetation fires are not the major sources of levoglucosan in precipitation in Lhasa. In addition, the annual levoglucosan flux at Lhasa is much higher than that in ice cores on the Tibetan Plateau. This study provides important insights into levoglucosan records in precipitation over the Tibetan Plateau, highlighting how levoglucosan variations could reflect fire changes from a single event to seasonal or annual time scales.