Enhanced Field Burning Derived Aerosols Across the Southeastern Tibetan Plateau in Spring

The Tibetan Plateau is the third pole of the world, regulating the climate of the northern hemisphere. Previous studies suggested that the atmospheric aerosols over Tibetan Plateau were obviously influenced by the BB transported from South and Southeast Asia. In fact, field burning is also an important form of BB in Southeast Asian countries. Every spring there is serious air pollution caused by field burning. However, there are still scientific gaps in the contribution of field burning to surrounding regional aerosols, especially on the Tibetan Plateau. To further identify the influence of field burning on the aerosols over the Southeastern Tibetan Plateau, we collected the PM2.5 samples and then analyzed the concentrations of TC and TN and their isotope during the March to June on Southeastern Tibetan Plateau. The δ13C and δ15N results showed that there was no significant difference (p > 0.05) between the field burning and the non-field burning periods. Furthermore, both δ13C and δ15N values were similar to the BB value, indicated the TC and TN were primarily derived from BB whether field burning or non-field burning periods. The concentrations of TC, and TN (6.5 ± 2.9 µg m-3, and 1.2 ± 0.4 µg m-3 respectively) during the field burning period (March to April) were significantly higher than during the non-field burning period (4.1 ± 1.7 µg m-3, p= 0.014; and 0.7 ± 0.3 µg m-3, p= 0.013, respectively). The active fires data, the smoke surface concentrations, backward trajectory, further indicated that the BB emissions from Southeast Asia during field burning period higher than during non-field burning period. This suggests that high BB emissions had significantly enhanced atmospheric aerosols concentrations and chemical composition in Southeastern Tibetan Plateau during the field burning period, which may further affect the plateau biodiversity and ecosystem.