摘要
生物质燃烧向大气中排放大量颗粒污染物,在中国,收获季节大量秸秆被直接露天燃烧处理,对区域环境质量和人体健康造成严重影响.对我国最主要的两种粮食作物玉米和小麦秸秆的露天燃烧进行模拟,分析颗粒物排放水平,特征及影响因素.玉米和小麦秸秆燃烧PM_(2.5)排放因子分别为1082.8和835.7~897.3 mg/kg.有机物是颗粒物最主要组分,总量占PM_(2.5)质量的42%~66%.Cl^-和K^+分别占PM_(2.5)总质量的4%~15%和2%~14%,K^+/EC值为0.5~3.8.各物种在颗粒物中所占比例与之前研究结果一致.秸秆含水量和燃烧温度影响PM_(2.5)排放水平和组成特征.随秸秆含水量增加,PM_(2.5)和OC的排放因子增加;秸秆含水量增加,燃烧温度逐渐降低,由生物质燃料释放进入烟气中的K^+和Cl^-比例逐渐减小导致二者在颗粒物中的比例降低.我国每年由玉米和小麦秸秆露天燃烧排放的PM_(2.5)和OC分别为92.7 Gg和47.5 Gg,在总量中占重要比例.
Large quantities of particulate pollutants are emitted into the atmosphere during biomass burning processes. In China, large amounts of agricultural residues are burned in the field during harvest seasons, which influence regional air quality and human health. Corn and wheat are two major crops grown in China, whose burning was simulated in this study. The controlled laboratory simulation of straw burning was performed in the Laboratory of Biomass Burning Simulation at Peking University Shenzhen Graduate School. The burning simulation system was improved and verified. Straw burning aerosols（PM2.5） samples were collected and measured by gravimetric method. Organic carbon（OC） and elemental carbon（EC） were measured by thermal/optical method. Water-soluble inorganic ions and organic matter were measured by ion chromatography. Emission level, characterization and influence factors of crop straw burning aerosols are discussed. PM2.5emission factors of corn and wheat straw burning are 1082.8 and 835.7-897.3 mg/kg, respectively. Organic matter（OM）, which is calculated by multiplying organic carbon（OC） by 1.3, is the major component of PM2.5, accounting for 42%-66% of the total mass. Nearly half（37%-50%） of OM are water soluble. Cl^- and K^＋are two major components among water-soluble inorganic ions, accounting for 4%-15% and 2%-14% of total particle mass, respectively. The K^＋/EC ratio is 0.5-3.8. The proportions of these species in PM2.5 are comparable to previous studies. Straw moisture content and burning temperature influence the emission level and characterization of straw burning aerosols. Emission factors of PM2.5 and OC increase with the increase of straw moisture content because of incomplete burning. With higher moisture content, more thermal energy is used for the evaporation of water, lowering the burning temperature. Then less proportion of K^＋and Cl^-are released from biomass into the smoke. Therefore, their contributions to the particle mass decrease with the increase of straw moisture content. The emissions of PM2.5 and OC/EC by crop straw burning in the field are estimated based on the emission factors obtained in this study. Corn and wheat burning in the field yield 92.7 Gg PM2.5 and 47.5 Gg OC every year in China, accounting for important fractions among the total mass.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2016年第4期356-362,共7页
Acta Chimica Sinica
基金
环保部公益性行业科研专项(No.201409010)
国家自然科学基金重大项目(Nos.91544214
21190052)
中国科学院战略性先导科技专项(No.XDB05010500)资助~~
关键词
生物质燃烧
秸秆
PM2.5
排放因子
特征
影响因素
biomass burning
crop straw
PM2.5
emission factor
characterization
influence factor
