华南农产品主产区2005—2014年秸秆露天燃烧污染物排放估算及时空分布

为了解华南农产品主产区秸秆露天燃烧大气污染物排放情况，通过室内模拟试验，实测该地区水稻、小麦、豆类、油菜、玉米、棉花和花生秸秆CO、CO₂、NO_x、C_xH_y和PM_2.5的排放因子，并基于统计年鉴计算出的研究区域农作物秸秆产量和露天燃烧量，对华南主产区4省2005—2014年间秸秆露天燃烧各类污染物的排放总量进行估算，并分析其时空动态变化。结果表明：不同农作物秸秆燃烧时CO、CO₂、NO_x、C_xH_y和PM_2.5的平均排放因子分别为165.32、1 231.76、1.94、38.47 g·kg^-1和7.54 g·kg^-1。2005—2014年，华南农产品主产区农作物秸秆产量范围59.361（福建）~185.890 Mt（云南）；秸秆燃烧量范围13.629（福建）~41.902 Mt（广东）；CO、CO₂、NO_x、C_xH_y和PM_2.5的排放总量分别为18 926.32、149 866.73、153.13、6 467.09 kt和870.33 kt。水稻是研究区域大气污染物的主要来源，对各类污染物贡献率为61.16%~84.83%。研究区域污染物时空分布结果显示，广东全省、广西中部和云南东部是大气污染物单位网格排放高值区，福建全省污染物排放较低且分散。研究区域各省不同污染物排放在时间上的变化存在差异。福建污染物排放呈下降趋势，广东、广西、云南呈上升趋势。

Temporal and spatial distribution of air pollutants emitted from field burning of straw crops in Southern China during 2005-2014

The objective of the present study was to estimate the emission of air pollutants from straw crop burning in four main crop production provinces of Southern China. Crop straw yield and amount of field combustion during 2005-2014 were calculated based on the statistical yearbook data. Indoor simulation experiments were also conducted to measure emission factors for CO, CO₂, NO_x, C_xH_y, and PM_2.5 in rice, wheat, beans, rape, maize, cotton, and peanut straw. The straw crop yield in Southern China ranged from 59.361 Mt to 185.890 Mt during the study period; the lowest being in Fujian Province and the highest being in Yunnan Province. The total amount of field combustion ranged from 13.629 Mt(in Fujian Province) to 41.902 Mt(in Guangdong Province). The average emission factors for CO, CO₂, NO_x, C_xH_y, and PM_2.5 from combustion of straw crops were 165.32, 1 231.76, 1.94, 38.47 g·kg^-1, and 7.54 g·kg^-1, respectively. Emissions of CO, CO₂, NO_x, C_xH_y, and PM_2.5 from simulated burning experiments were 18 926.32, 149 866.73, 153.13, 6 467.09 kt, and 870.33 kt, respectively. Rice was the main source of air pollutants throughout the study areas, accounting for 61.16% to 84.83% of all types of pollutants. The temporal distribution of pollutants varied in each province, with emissions of pollutants having a decreasing trend in Fujian and an increasing trend in Guangdong, Guangxi, and Yunnan. The spatial pattern of pollution emissions was explicit, with a high area of air pollutant emission per unit grid in Guangdong, central Guangxi, and Eastern Yunnan, while it was relatively low and dispersed in Fujian Province. It can be concluded that burning crop residue contributes to environmental pollution in the study areas; thus, efforts should be made to develop alternative crop residue management techniques.