牛粪燃烧实时排放挥发性有机物特征研究

在实验室模拟青海和西藏2种牛粪在民用炉具中的燃烧过程，采用稀释通道系统与质子转移飞行时间质谱（PTR-TOF-MS）在线分析牛粪燃烧排放的挥发性有机物（VOCs），通过电子秤实时记录燃料质量的动态变化，获得牛粪燃烧排放VOCs浓度的时间序列与实时排放因子.结果表明，70g牛粪一次燃烧过程持续1100~1500s.牛粪燃烧排放VOCs浓度的时间变化趋势总体上呈单峰分布；西藏牛粪在燃烧450s左右VOCs浓度达到峰值7.92×10^-6；青海牛粪在燃烧400s左右VOCs浓度达到峰值6.01×10^-6.牛粪燃烧VOCs实时排放因子变化范围为40.74~156.88mg/g，趋势不同于VOCs浓度变化，随燃烧过程进行排放因子呈上升趋势.牛粪燃烧至3~4min左右，VOCs排放因子最低.甲醇、甲醛和乙醛3种VOCs排放因子占比最大，其中西藏牛粪燃烧3种VOCs排放占比分别为24.0%±1.9%、11.9%±1.8%和27.4%±1.4%，青海牛粪为22.0%±1.1%、13.3%±2.9%和17.7%±4.6%.本研究首次给出了牛粪燃烧VOCs实时排放因子，可为高时间分辨率排放清单建立和青藏高原地区室内空气污染的健康效应研究提供基础数据.

Real-time emission of volatile organic compounds from cow dung combustion

The burning for two kinds of cow dung from Qinghai and Tibet in domestic stove was simulated at a laboratory. The real-time emission concentrations of volatile organic compounds (VOCs) from their burning were obtained by a dilution sampling system and a proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS). The consumed amounts of cow dung during combustion processes were recorded using an electronic balance. The real-time emission factors were calculated. Results showed that the combustion processes of 70g cow dung lasted for 1100~1500 seconds. The time series of VOCs concentrations from cow dung burning mostly showed a single peak distribution. Total VOCs concentrations for the cow dung burning from Tibet peaked at 450s with a concentration of 7.92×10^-6. The total VOCs concentrations for the cow dung burning from Qinghai peaked at 400s with a concentration of 6.01×10^-6. The real-time emission factors of VOCs emitted from cow dung burning ranged in 40.74~156.88mg/g. The variation trends of the emission factors for VOCs were different from those of VOCs concentrations, and they exhibited increasing trend along with the combustion process. The lowest emission factors of VOCs were found at 3~4 minutes after the cow dung burning. For the burning of cow dung from Tibet, methanol, formaldehyde and acetaldehyde accounted for the largest proportion of total VOCs emissions, as 24%±1.9%, 11.9%±1.8% and 27.4%±1.4%, respectively. For the burning of cow dung from Qinghai, the corresponding mass percentages were 22.0%±1.1%, 13.3%±2.9% and 17.7%±4.6%, respectively. This study firstly gives the real-time emission factors of VOCs from cow dung burning, which can provide basic data for the establishment of emission inventory with high time resolution and also helpful for researches on human health effects as the exposure to domestic fuels burning in Qinghai-Tibet Plateau region.