东南亚生物质燃烧对我国春季PM_(2.5)质量浓度影响的数值模拟

Modeling the Impacts of Biomass Burning in Southeast Asia on PM_(2.5) over China in Spring

为研究东南亚生物质燃烧对我国的影响,利用NAQPMS(嵌套网格空气质量预报模式系统)模拟分析了2013年3月我国及东南亚污染物质量浓度分布,以及东南亚国家生物质燃烧对我国ρ(PM_(2.5))的贡献.结果表明:NAQPMS模式可较好地再现ρ(PM_(2.5))的时空演变规律.在我国西南部分地区,东南亚生物质燃烧贡献与当地人为源相当,并且在ρ(PM_(2.5))较高时尤为明显.东南亚生物质燃烧对我国的影响主要有两个路径:第一个路径是缅甸向云南等地的输送,对云南ρ(PM_(2.5))的月均贡献达到20μg/m^3(贡献率为30%),是云南本地生物质燃烧贡献的2倍左右,日均贡献甚至可达到34μg/m3(贡献率为43%),高于我国人为源贡献(28μg/m3)和贡献率(36%);第二个路径是老挝和越南向云南与广西交界的输送,对南宁ρ(PM_(2.5))的月均贡献为10μg/m3,日均贡献高值区间为20~40μg/m3.我国人为源对东南亚的影响较小,对ρ(PM_(2.5))月均贡献率在10%以内,主要集中在越南和东南亚南部沿海城市.东南亚人为源对我国的影响也较小,ρ(PM_(2.5))月均贡献在2μg/m3以下.研究显示,东南亚生物质燃烧对我国特别是西南地区产生的影响不可忽视.

Biomass burning in Southeast Asia is receiving much attention as a significant contributor to air pollution in East Asia. A simulation in March 2013 was performed to assess the impact of biomass burning from different countries in Southeast Asia on China by a three-dimensional regional chemical transport model（ NAQPMS） with an online tracer-tagged module. The model reproduced PM2.5accurately,with correlation coefficients from 0. 40-0. 76 in Southern China and Southeast Asia. The results indicate that biomass burning in Southeast Asia significantly contributed to surface PM2.5in Southwestern China,which was even comparable to local anthropogenic emissions in some regions. There were two major source regions from Southeast Asia to China in the boundary layer. In the first source region,PM2.5was transported from Myanmar to Yunnan Province by climbing the plateau. The transported monthly mean ρ（ PM2.5）reached 20 μg/m3（ 30% of total PM2.5）,twice the contribution of local biomass burning. In one case, regional transport from Myanmar even contributed 34 μg/m3（ 43%） PM2.5,which was higher than anthropogenic emissions in China（ 28 μg/m3,36%）. In a second one,PM2.5emitted by biomass burning inLaos and Vietnam was transported to Yunnan and Guangxi and further up to Guizhou. Although it contributed 10 μg/m3to monthly mean PM2.5in Nanning,it reached 20-40 μg/m3in transported episodes. Compared with the impact of biomass burning on China,regional transport of anthropogenic emissions in China to Southeast Asia was less（ below 10%）,which was in cities along the South China Sea in Vietnam. The impact of anthropogenic emissions in Southeast Asia on Southern China was below 2 μg/m3.