稻草烟尘中有机碳/元素碳及水溶性离子的组成

选取我国6种稻草,通过自制的生物质焚烧装置模拟秸秆露天焚烧.采用Model 2001A热/光分析仪和ISC 2000/ISC3000离子色谱仪测定了阴燃、明燃烟尘中有机碳(OC)、元素碳(EC)与水溶性离子的含量.结果表明,明燃条件下稻草中OC排放因子(EFOC)均值为(6.37±1.86)g·kg-1,EC排放因子(EFEC)均值为(1.07±0.30)g·kg-1;阴燃条件下稻草中EFOC均值为(37.63±6.26)g·kg-1,EFEC均值为(4.98±1.42)g·kg-1.同一品种稻草燃烧排放出的PM、OC与EC变化趋势一致.明燃时稻草中的OC/EC均值为5.96,阴燃时比值均值为7.80,OC/PM几乎不受燃烧状态的影响,阴燃、明燃时EC/PM分别在0.06~0.08、0.08~0.11范围内,通过EC/PM比值可以初步判断燃烧状态的趋势,两种燃烧方式中排放的OC、EC相关性达到0.97,在0.01水平上相关性显著.阴离子中,Cl-含量最高,明燃时稻草中Cl-的排放因子均值为(0.246±0.150)g·kg-1,阴燃下为(0.301±0.274)g·kg-1,明燃时K+排放因子均值为(0.118±0.051)g·kg-1,阴燃时排放因子远低于明燃排放量,均值为(0.053±0.031)g·kg-1.水溶性Na+在阴燃条件下的排放因子均高于明燃状态下的排放.明燃条件下水溶性离子间的相关性比阴燃时显著.通过OC/EC比值可以将稻草与石化燃料及其他一些生物质燃烧区分开,而水溶性离子中的K+/Na+、Cl-/Na+比值也可以将稻草与一些树木类焚烧区别开来.

Composition of Organic Carbon/Elemental Carbon and Water-soluble Ions in Rice Straw Burning

Six types of rice straw were selected in China in this paper, the homemade biomass combustion devices were used to simulate the outdoor burning. The concentrations of organic carbon(OC), elemental carbon(EC) and water-soluble ions in particular matter produced by the flaming and smoldering were analyzed using Thermal Optical Carbon Analyzer(Model 2001A) and Ion Chromatography(ISC 2000/ISC 3000). The results showed that the mean value of OC(EF_OC) and EC(EF_EC) emission factors were(6.37±1.86) g·kg^-1 and(1.07±0.30) g·kg^-1 under the flaming conditions, respectively, while under the smoldering conditions the two mean values were(37.63±6.26) g·kg^-1 and(4.98±1.42) g·kg^-1. PM, OC and EC emitted from the same kind of rice straw had similar change trends. The average values of OC/EC under flaming and smoldering were 5.96 and 7.80, and the value of OC/PM was almost unchanged along with the combustion state. Nevertheless, the values of EC/PM under flaming and smoldering were 0.06-0.08 and 0.08-0.11, respectively. The trend of combustion state could be determined using the ratio of EC/PM and the R² of emitted OC and EC through those two types of combustion reached 0.97, which was significantly correlated at the 0.01 level. Among the anions, Cl^- showed the highest concentration, the results indicated that the average value of of Cl^- emission factor was(0.246±0.150) g·kg^-1 under flaming, while it was(0.301±0.274) g·kg^-1 under smoldering. However, A big difference between flaming and smoldering was found in the average value of K⁺emission factor, where(0.118±0.051) g·kg^-1 of the former was significantly higher than the latter(0.053±0.031) g·kg^-1. When it came to Na⁺, the result of smoldering was significantly higher than that of flaming. The correlation between water-soluble ions in flaming was more significant than smoldering. Rice straw burning could be distinguished from fossil fuels and some other biomass burning by the OC/EC ratio, and it could also be distinguished from sort of trees burning by the ratio of K⁺/Na⁺, Cl^-/Na⁺in water-soluble ions.