长三角地区秸秆燃烧排放因子与颗粒物成分谱研究

Emission Factors and PM Chemical Composition Study of Biomass Burning in the Yangtze River Delta Region

为获取长三角地区秸秆燃烧污染物排放因子及其颗粒物成分谱,利用自行设计开发的开放式燃烧源排放测试系统,选取小麦、水稻、油菜、豆秸和薪柴等5类典型作物秸秆,分别采用露天焚烧和炉灶燃烧2种燃烧方式,实测其气态污染物和颗粒物排放特征.结果表明,露天燃烧各类秸秆的CO、NOx和PM2.5平均排放因子约为28.7、1.2和2.65 g·kg-1,由于炉灶氧含量相对较低,燃烧不充分,其污染物排放因子总体高于露天燃烧,分别为81.9、2.1和8.5 g·kg-1.各类秸秆中,油菜的排放水平相对较高.含碳组分(OC和EC)是生物质秸秆燃烧产生PM2.5的主要组成,在露天燃烧中OC和EC的质量分数分别占(38.92±13.93)%和(5.66±1.54)%;炉灶燃烧中OC和EC分别为(26.37±10.14)%和(18.97±10.76)%.Cl-、K+等水溶性离子也有较大贡献,在露天燃烧中分别为(13.27±6.82)%和(12.41±3.02)%;在炉灶燃烧中分别为(16.25±9.34)%和(13.62±7.91)%.小麦、水稻、油菜和豆秸等作物秸秆露天燃烧排放颗粒物的K+/OC值分别为0.30、0.52、0.49和0.15,这些特征值可用于判断长三角区域空气质量受秸秆燃烧排放影响的程度,为大气污染来源解析提供直接的判断依据.

The emission characteristics of five typical crops,including wheat straw,rice straw,oil rape straw,soybean straw and fuel wood,were investigated to explore the gas and particulates emission of typical biomass burning in Yangzi-River-Delta area. The straws were tested both by burning in stove and by burning in the farm with a self-developed measurement system as open burning sources. Both gas and fine particle pollutants were measured in this study as well as the chemical composition of fine particles. The results showed that the average emission factors of CO,NOxand PM2. 5in open farm burning were 28. 7 g·kg- 1,1. 2 g·kg- 1and 2. 65 g·kg- 1,respectively. Due to insufficient burning in the low oxygen level environment,the emission factors of stove burning were higher than those of open farm burning,which were 81. 9 g·kg- 1,2. 1 g·kg- 1and 8. 5 g·kg- 1,respectively. Oil rape straw had the highest emission factors in all tested straws samples. Carbonaceous matter,including organic carbon( OC) and element carbon( EC),was the foremost component of PM2. 5from biomass burning. The average mass fractions of OC and EC were( 38. 92 ± 13. 93) % and( 5. 66 ± 1. 54) % by open farm burning and( 26. 37 ± 10. 14) % and( 18. 97 ± 10. 76) % by stove burning. Water soluble ions such as Cland K+had a large contribution. The average mass fractions of Cl-and K+were( 13. 27 ± 6. 82) % and( 12. 41 ± 3. 02) % by open farm burning,and were( 16. 25 ± 9. 34) % and( 13. 62 ± 7. 91) % by stove burning. The K+/ OC values of particles from wheat straw,rice straw,oil rape straw and soybean straw by open farm burning were 0. 30,0. 52,0. 49 and 0. 15,respectively,which can be used to evaluate the influence on the regional air quality in YRD area from biomass burning and provide direct evidence for source apportionment.