Indication of primary biogenic contribution to BrC over a high altitude location in the southeastern Tibet

To investigate the characteristics of primary biogenic organic aerosol (PBOA) and correlations with brown carbon (BrC) light absorption in the southeastern Tibetan Plateau (TP), the total suspended particle (TSP) samples were collected at a high altitude site (Lulang) from November 2015 to November 2016. The seasonal variations of PBOA tracers (including arabitol, mannitol, and glucose) were obtained. Elevated arabitol, mannitol and glucose concentrations were observed in monsoon (54, 10 and 18 times higher than in winter, respectively), largely due to the intensive contributions of seasonal biological origin. The highest percentages of fungal-spore-derived organic carbon (OC) and plant-debris OC were obtained in monsoon season with 23.4% and 4.0%, respectively. The results indicated that monsoon PBOA can be the contributor to BrC chromophores in the southeastern Tibetan Plateau. Further studies are needed to investigate the relation between PBOA components and BrC light absorption properties.