Ozone pollution in the west China rain zone and its adjacent regions, Southwestern China: Concentrations, ecological risk, and Sources
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Located in the transitional region between the Sichuan Basin (SCB) and Qinghai-Tibetan Plateau (QTP), the West China Rain Zone (WCRZ) is a large-scale ecotone and partially belongs to the Southwest China Mountains, which is one of the world's 34 biodiversity hotspots. Using observation data from national air quality stations and our own monitoring data, we investigated the risk from O3 to vegetation and the major source-region of O3 for two UNESCO (i.e., United Nations Educational, Scientific and Cultural Organization) world heritage properties (Mt. Qingcheng and Mt. Emei) and one city (Ya'an) in the WCRZ. The results show that the annual mean maximum daily 8-h average (MDA8) O3 concentration in Mt. Qingcheng (54 ppb) was higher than that in the adjacent SCB cities (38-48 ppb). The acute and chronic risk levels from O3 to vegetation were also higher in Mt. Qingcheng than at all the other sites. The mean MDA8 O3 concentrations and the O3 risk levels to vegetation in Mt. Emei and Ya'an fell in the range of that at the SCB and QTP cities. However, O3 exposures at all the WCRZ, SCB, and QTP sites exceeded the empirical critical loads for natural ecosystems, forest trees, and highly O3-sensitive plants. The SCB was identified as the largest source-region of O3 for Mt. Qingcheng and Mt. Emei but other Chinese regions and northern India also had considerable contributions. To protect biodiversity and ecosystem services, there is a need to further systematically study O3 and its ecological impacts for the entire WCRZ.
author list (cited authors)
Cao, Y., Qiao, X., Hopke, P. K., Ying, Q. i., Zhang, Y., Zeng, Y., Yuan, Y., & Tang, Y. a.