Biomass burning reconstruction analysing lacustrine sediment cores from the Tibetan plateau

Abstract

The present PhD research gives information about Holocene fire events and vegetation changes occurred in the Tibetan Plateau. Asiatic region is a strategic area to explore biomarkers accumulated in lacustrine sedimentary cores during the past millennia. In order to improve the scientific knowledge in this area, sediment samples from lakes Paru Co and Hala Hu, in the South-Eastern and North-Eastern Tibetan Plateau respectively, were analysed. Accelerated Solvent Extraction technique was used to extract organic compounds from the samples. Analyses were performed with gas and liquid chromatographers coupled with mass spectrometers. The molecules of interest are monosaccharide anhydrides (MAs), specific markers of vegetation fires, polycyclic aromatic hydrocarbons, as combustion proxies, n-alkanes, indicators of vegetation, and faecal sterols, indicators of past human and grazing animals presence. Paru Co MAs results show that a very high intensity of biomass burning recorded in the Early Holocene samples is parallel with the drier climate of the same period, following the deglaciation. The local ecosystem and vegetation changes are in agreement with intensity’s variations in the Indian Summer Monsoon rainfall. Hala Hu MAs results instead show higher fire intensity between 4.5 and 7 ky BP. The information obtained from these organic geochemical data were compared with other records and charcoal data, allowing the contextualization of the biomass burning events.