Wiedinmyer Christine, Friedli Hans
National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, Colorado 80305, USA.
Environ Sci Technol. 2007 Dec 1;41(23):8092-8. doi: 10.1021/es071289o.
Recent studies have shown that emissions of mercury (Hg), a hazardous air pollutant, from fires can be significant. However, to date, these emissions have not been well-quantified for the entire United States. Daily emissions of Hg from fires in the lower 48 states of the United States (LOWER48) and in Alaska were estimated for 2002-2006 using a simple fire emissions model. Emission factors of Hg from fires in different ecosystems were compiled from published plume studies and from soil-based assessments. Annual averaged emissions of Hg from fires in the LOWER48 and Alaska were 44 (20-65) metric tons yr(-1), equivalent to approximately 30% of the U.S. EPA 2002 National Emissions Inventory for Hg. Alaska had the highest averaged monthly emissions of all states; however, the emissions have a high temporal variability. Emissions from forests dominate the inventory, suggesting that Hg emissions from agricultural fires are not significant on an annual basis. The uncertainty in the Hg emission factors due to limited data leads to an uncertainty in the emission estimates on the order of +/-50%. Research is still needed to better constrain Hg emission factors from fires, particularly in the eastern U.S. and for ecosystems other than forests.
近期研究表明，火灾产生的汞（Hg）这种有害空气污染物的排放量可能很大。然而，迄今为止，美国全国范围内的这些排放量尚未得到充分量化。利用一个简单的火灾排放模型估算了2002年至2006年美国本土48个州（LOWER48）和阿拉斯加火灾产生的汞日排放量。不同生态系统火灾产生汞的排放因子是根据已发表的烟羽研究和基于土壤的评估汇编而成。LOWER48和阿拉斯加火灾产生汞的年平均排放量为44（20 - 65）公吨/年，约占美国环境保护局2002年汞国家排放清单的30%。阿拉斯加的月平均排放量在所有州中最高；然而，排放量具有很高的时间变异性。森林火灾的排放占清单的主导地位，这表明农业火灾产生的汞排放从年度来看并不显著。由于数据有限，汞排放因子的不确定性导致排放估算的不确定性约为±50%。仍需开展研究以更好地确定火灾产生汞的排放因子，特别是在美国东部以及森林以外的生态系统。
