Influence of fuel moisture, charge size, feeding rate and air ventilation conditions on the emissions of PM, OC, EC, parent PAHs, and their derivatives from residential wood combustion

Controlled combustion experiments were conducted to investigate the influence of fuel charge size, moisture, air ventilation and feeding rate on the emission factors (EFs) of carbonaceous particulate matter, parent polycyclic aromatic hydrocarbons (pPAHs) and their derivatives from residential wood combustion in a typical brick cooking stove. Measured EFs were found to be independent of fuel charge size, but increased with increasing fuel moisture. Pollution emissions from the normal burning under an adequate air supply condition were the lowest for most pollutants, while more pollutants were emitted when an oxygen deficient atmosphere was formed in the stove chamber during fast burning. The impacts of these factors on the size distribution of emitted particles was also studied. Modified combustion efficiency and the four investigated factors explained 68%, 72%, and 64% of total variations in EFs of PM, organic carbon, and oxygenated PAHs, respectively, but only 36%, 38% and 42% of the total variations in EFs of elemental carbon, pPAHs and nitro-PAHs, respectively.     

Influence of fuel mass load, oxygen supply and burning rate on emission factor and size distribution of carbonaceous particulate matter from indoor corn straw burning

The uncertainty in emission estimation is strongly associated with the variation in emission factor (EF),which could be influenced by a variety of factors such as fuel properties,stove type,fire management and even methods used in measurements.The impacts of these factors are complicated and often interact with each other.Controlled burning experiments were conducted to investigate the influences of fuel mass load,air supply and burning rate on the emissions and size distributions of carbonaceous particulate matter (PM) from indoor corn straw burning in a cooking stove.The results showed that the EFs of PM (EFPM),organic carbon (EFOC) and elemental carbon (EFEC) were independent of the fuel mass load.The differences among them under different burning rates or air supply amounts were also found to be insignificant (p > 0.05) in the tested circumstances.PM from the indoor corn straw burning was dominated by fine PM with diameter less than 2.1 μm,contributing 86.4%±3.9% of the total.The size distribution of PM was influenced by the burning rate and air supply conditions.On average,EF PM,EF OC and EF EC for corn straw burned in a residential cooking stove were (3.84±1.02),(0.846±0.895) and (0.391±0.350) g/kg,respectively.EF PM,EF OC and EF EC were found to be positively correlated with each other (p < 0.05),but they were not significantly correlated with the EF of co-emitted CO,suggesting that special attention should be paid to the use of CO as a surrogate for other incomplete combustion pollutants.     

Influence of rice straw burning on the levels of polycyclic aromatic hydrocarbons in agricultural county of Taiwan

Atmospheric particulate and polycyclic aromatic hydrocarbons (PAHs) size distribution were measured at Jhu-Shan (a rural site) and Sin-Gang (a town site) in central Taiwan during the rice straw burning and non-burning periods. The concentrations of total PAHs accounting for a roughly 58% (34%) increment in the concentrations of total PAHs due to rice-straw burning. Combustion-related PAHs during burning periods were 1.54–2.57 times higher than those during non-burning periods. The mass median diameter (MMD) of 0.88–1.21 m in the particulate phase suggested that rice-straw burning generated the increase in coarse particle number. Chemical mass balance (CMB) receptor model analyses showed that the primary pollution sources at the two sites were similar. However, ricestraw burning emission was specifically identified as a significant source of PAH during burning periods at the two sites. Open burning of rice straws was estimated to contribute approximately 6.3%–24.6% to total atmospheric PAHs at the two sites.     

Emission factors of particulate matter, CO and CO2 in the pyrolytic processing of typical electronic wastes

A self-designed experimental device was employed to simulate the pyrolytic dismantling process of selected electronic wastes(E-wastes), including printed wiring boards(PWBs)and plastic casings. The generated particulate matter(PM) of different particle sizes, carbon monoxide(CO) and carbon dioxide(CO_2) were determined, and the corresponding emission factors(EFs) were estimated. Finer particles with particle sizes of 0.4–2.1 μm accounted for78.9% and 89.3% of PM emitted by the pyrolytic processing of PWBs and plastic casings,respectively, and the corresponding EFs were 9.68 ± 4.81 and 18.49 ± 7.2 g/kg, respectively.The EFs of CO and CO_2 from PWBs and plastic casings were 55.9 ± 26.9 and 1182 ± 439 g/kg,and 133.6 ± 34.6 and 2827 ± 276 g/kg, respectively. Compared with other emission sources,such as coal, biomass, and traffic exhaust, the EFs of E-wastes were relatively higher,especially for PM. There were significant positive correlations(p 0.05) of the initial contents of carbon and nitrogen in PWBs with the related EFs of PM, CO, and CO_2, while the correlations for plastic casings were insignificant. The EFs of CO of PWBs were significantly positively correlated with the corresponding EFs of PM and the parent polycyclic aromatic hydrocarbons(PAHs); however, the same result was not observed for plastic casings.     

Fine particle-bound PAHs derivatives at mountain background site (Mount Tai) of the North China: Concentration, source diagnosis and health risk assessment

Ten nitrated polycyclic aromatic hydrocarbons (nPAHs) and 4 oxygenated polycyclic aromatic hydrocarbons (oPAHs) in fine particulate matter (PM_2.5) samples from Mount Tai were analyzed during summer (June to August), 2015. During the observation campaign, the mean concentration of total nPAHs and oPAHs was 31.62 pg/m³ and 0.15 ng/m³, respectively. Two of the monitored compounds, namely 9-nitro-anthracene (9N-ANT) (6.86 pg/m³) and 9-fluorenone (9FO) (0.05 ng/m³) were the predominant compounds of nPAHs and oPAHs, respectively. The potential source and long-range transportation of nPAHs and oPAHs were investigated by the positive matrix factorization (PMF) method and the potential source contribution function (PSCF) methods. The results revealed that biomass/coal burning, gasoline vehicle emission, diesel vehicle emission and secondary formation were the dominant sources of nPAHs and oPAHs, which were mainly from Henan province and Beijing-Tianjin-Hebei region and Bohai sea. The incremental life cancer risk (ILCR) values were calculated to evaluate the exposure risk of nPAHs and oPAHs for three group people (infant, children and adult), and the values of ILCR were 7.02 × 10^?10, 3.49 × 10^?9 and 1.41 × 10^?8 for infant, children and adults, respectively. All these values were lower than the standard of EPA (Environmental Protection Agency) (<10^?6), indicating acceptable health risk of nPAHs and oPAHs.     

Characteristics of particulate-bound polycyclic aromatic hydrocarbons emitted from industrial grade biomass boilers

Polycyclic aromatic hydrocarbons(PAHs) are carcinogenic or mutagenic and are important toxic pollutants in the flue gas of boilers. Two industrial grade biomass boilers were selected to investigate the characteristics of particulate-bound PAHs: one biomass boiler retro-fitted from an oil boiler(BB1) and one specially designed(BB2) biomass boiler. One coal-fired boiler was also selected for comparison. By using a dilution tunnel system, particulate samples from boilers were collected and 10 PAH species were analyzed by gas chromatography–mass spectrometry(GC–MS). The total emission factors(EFs) of PAHs ranged from 0.0064 to0.0380 mg/kg, with an average of 0.0225 mg/kg, for the biomass boiler emission samples. The total PAH EFs for the tested coal-fired boiler were 1.8 times lower than the average value of the biomass boilers. The PAH diagnostic ratios for wood pellets and straw pellets were similar.The ratio of indeno(1,2,3-cd)pyrene/[indeno(1,2,3-cd)pyrene + benzo(g,h,i)perylene] for the two biomass boilers was lower than those of the reference data for other burning devices, which can probably be used as an indicator to distinguish the emission of biomass boilers from that of industrial coal-fired boilers and residential stoves. The toxic potential of the emission from wood pellet burning was higher than that from straw pellet burning, however both of them were much lower than residential stove exhausts.     

Emission factors of polycyclic aromatic hydrocarbons from domestic coal combustion in China

Domestic coal stove is widely used in China, especially for countryside during heating period of winter, and polycyclic aromatic hydrocarbons （PAHs） are important in flue gas of the stove. By using dilution tunnel system, samples of both gaseous and particulate phases from domestic coal combustion were collected and 18 PAH species were analyzed by GC-MS. The average emission factors of total 18 PAH species was 171.73 mg/kg, ranging from 140.75 to 229.11 mg/kg for bituminous coals, while was 93.98 mg/kg, ranging from 58.48 to 129.47 mg/kg for anthracite coals. PAHs in gaseous phases occupied 95% of the total of PAHs emission of coal combustion. In particulate phase, 3-ring and 4- ring PAHs were the main components, accounting for 80% of the total particulate PAHs. The total toxicity potency evaluated by benzo[a]pyrene-equivalent carcinogenic power, sum of 7 carcinogenic PAH components and 2,3,7,8-tetrachlorodibenzodioxin had a similar tendency. And as a result, the toxic potential of bituminous coal was higher than that of anthracite coal. Efficient emission control should be conducted to reduce PAH emissions in order to protect ecosystem and human health.     

Atmospheric particle-bound polycyclic aromatic compounds over two distinct sites in Pakistan: Characteristics, sources and health risk assessment

Much attention is drawn to polycyclic aromatic hydrocarbons（PAHs） as an air pollutant due to their toxic, mutagenic and carcinogenic properties. Therefore, to understand the levels, seasonality, sources and potential health risk of PAHs in two distinct geographical locations at Karachi and Mardan in Pakistan, total suspended particle（TSP） samples were collected for over one year period. The average total PAH concentrations were 31.5 ± 24.4 and 199 ± 229 ng/m³ in Karachi and Mardan, re...     

Characteristics of nanoparticles emitted from burning of biomass fuels

The characteristics of the particles of the smoke that is emitted from the burning ofbiomass fuels were experimentally investigated using a laboratory-scale tube furnace and different types of biomass fuels： rubber wood, whole wood pellets and rice husks. Emitted amounts of particles, particle-bound polycyclic aromatic hydrocarbons （PAHs） and water-soluble organic carbon （WSOC） are discussed relative to the size of the emitted particles, ranging to as small as nano-size （〈70 nm）, and to the rate of heating rate during combustion, differential thermal analysis （DTA） and thermogravimetric analysis （TG） techniques were used to examine the effect of heating rate and biomass type on combustion behaviors relative to the characteristics of particle emissions. In the present study, more than 30% of the smoke particles from the burning ofbiomass fuel had a mass that fell within a range of 〈 100 nm. Particles smaller than 0.43 μm contributed greatly to the total levels of toxic PAHs and WSOC. The properties of these particles were influenced by the fuel component, the combustion conditions, and the particle size. Although TC--DTA results indicated that the heating rate in a range of 10-20℃did not show a significant effect on the combustion properties, there was a slight increase in the decomposition temperature as heating rate was increased. The nano-size particles had the smallest fraction of particle mass and particle-bound PAHs, but nonetheless these particles registered the largest fraction of particle-bound WSOC.     

Effect of central ventilation and air conditioner system on the concentration and health risk from airborne polycyclic aromatic hydrocarbons

Central ventilation and air conditioner systems are widely utilized nowadays in public places for air exchange and temperature control,which significantly influences the transfer of pollutants between indoors and outdoors.To study the effect of central ventilation and air conditioner systems on the concentration and health risk from airborne pollutants,a spatial and temporal survey was carried out using polycyclic aromatic hydrocarbons (PAHs) as agent pollutants.During the period when the central ventilation system operated without air conditioning (AC-off period),concentrations of 2-4 ring PAHs in the model supermarket were dominated by outdoor levels,due to the good linearity between indoor air and outdoor air (rp>0.769,p<0.05),and the slopes (1.2-4.54) indicated that ventilating like the model supermarket increased the potential health risks from low molecular weight PAHs.During the period when the central ventilation and air conditioner systems were working simultaneously (AC-on period),although the total levels of PAHs were increased,the concentrations and percentage of the particulate PAHs indoors declined significantly.The BaP equivalency (BaPeq) concentration indicated that utilization of air conditioning reduced the health risks from PAHs in the model supermarket.     

长三角地区秸秆燃烧排放因子与颗粒物成分谱研究

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.     

武汉市大气PM2.5中多环芳烃的分布特征及来源

为研究武汉市大气质量状况,在武汉市ID（工业区）、DT（中心城区）、BG（植物园）设3个采样点,连续1 a同步采集了大气中的PM_2.5（细颗粒物）样品,并研究了其中PAHs（多环芳烃）的质量浓度、来源和健康风险.结果表明,武汉市ID、DT、BG采样点的ρ（PAHs）年均值分别为（75.60±28.12）（59.77±22.81）（24.27±9.15）ng/m3,并呈冬季最高、夏季最低的季节性变化趋势.PMF（正定矩阵因子分析）结果显示,ID、DT、BG采样点的PAHs的主要来源分别为燃煤和扬尘（35%和33%）、机动车和扬尘（30%和34%）、机动车和木质燃烧（33%和32%）,在ID和DT采样点,扬尘对大气颗粒物中PAHs的贡献都很大,而燃煤和木质燃烧分别是ID和BG采样点PAHs的重要来源,在3个采样点中,机动车对颗粒物中PAHs贡献都较大,尤其是DT和BG采样点,机动车的贡献都超过30%.利用后向轨迹模型分析采样期间武汉市的气团来源,并结合每天的ρ（PAHs）发现,不同聚类气团对应的ρ（PAHs）差异很小,表明区域传输对武汉市PAHs贡献不大.通过武汉市大气颗粒物中PAHs吸入风险评估发现,武汉市PAHs的吸入风险范围在10-7~10-5之间,ID和DT采样点的部分人群的吸入风险稍高于安全范围（10-6以下）,有潜在的致癌风险.      

煤燃烧超细颗粒物的粒径分布及数浓度排放特征试验

利用快速迁移率粒径谱仪(fast mobility particle sizer,FMPS)对煤燃烧排放的超细颗粒物粒径分布特征进行测量研究,并对单位质量煤粉燃烧产生的超细颗粒物数量排放因子进行分析.结果表明,煤燃烧超细颗粒物数浓度粒径谱呈对数双峰分布,颗粒几何平均粒径(the geometry mean diameter,GMD)约为23.1 nm.在燃烧阶段,煤燃烧超细颗粒物数浓度随时间呈指数增长,各模态颗粒物数浓度与煤粉量呈线性相关关系,单位质量煤粉燃烧产生的核模态颗粒物数量排放因子为(1.50±0.64)×1010个·mg-1,爱根核模态颗粒为(1.18±0.56)×1010个·mg-1,积聚模态颗粒物为(0.19±0.06)×1010个·mg-1,总颗粒物为(2.87±1.09)×1010个·mg-1.在扩散过程中,颗粒粒径随时间呈线性增长,粒径增长速率与煤粉量呈线性相关关系.单位质量煤粉燃烧排放的颗粒粒径平均增长速率为7.5 nm·h-1·mg-1.     

Exposure measurement, risk assessment and source identification for exposure of traffic assistants to particle-bound PAHs in Tianjin, China

To investigate the levels of exposure to particulate-bound polycyclic aromatic hydrocarbon(PAH) and to estimate the risk these levels pose to traffic assistants(TAs) in Tianjin(a megacity in North China), a measurement campaign(33 all-day exposure samples, 25 occupational-exposure samples and 10 indoor samples) was conducted to characterize the TAs' exposure to PAHs, assess the cancer risk and identify the potential sources of exposure. The average total exposure concentration of 14 PAHs was approximately 2871 ± 928 ng/m3(on-duty), and 1622 ± 457 ng/m3(all-day). The indoor PAHs level was 1257 ± 107 ng/m3. After 8000 Monte Carlo simulations, the cancer risk resulting from exposure to PAHs was found to be approximately 1.05 × 10-4. A multivariate analysis was applied to identify the potential sources, and the results showed that, in addition to vehicle exhaust, coal combustion and cooking fumes were also another two important contributors to personal PAH exposure. The diagnostic ratios of PAH compounds agree with the source apportionment results derived from principal component analysis.     

广西十万大山背景点PM2.5中非极性有机气溶胶组成及来源解析

大气细颗粒物(PM_2.5)中的非极性化合物包括多环芳烃（PAHs）和正构烷烃（n-alkanes）等,通常用于识别污染来源,且对人体健康和环境有很重要的影响.为探究广西背景点PM_2.5中非极性有机气溶胶的污染特征及来源,于2017年11月至2018年10月,对野外采集的PM_2.5样品分析了其中17种多环芳烃和20种正构烷烃.结果表明,多环芳烃和正构烷烃全年的平均值分别为（4.28±4.25）ng·m^-3和（13.7±14.72）ng·m^-3;季节变化规律均是：冬季[（7.86±5.19）ng·m^-3和（27.51±16.9）ng·m^-3]>春季[（2.73±1.76）ng·m^-3和（7.64±4.71）ng·m^-3]>秋季[（2.34±1.45）ng·m^-3和（7.01±4.55）ng·m^-3]>夏季[（1.91±1.67）ng·...     

树木模拟燃烧排放烟尘中水溶性离子的组成

模拟林火中生物质的两种燃烧方式,明燃和闷燃,对10种乔木的干树枝和绿树枝进行室内燃烧试验,测定了排放烟尘中的水溶性离子.结果表明,干树枝明燃烟尘中水溶性离子的平均总含量为(28.88±17.54)g·kg~(-1).SO_4~(2-)、Cl~-、K~+是主要组分,其平均排放因子为101.0~118.2 mg·kg~(-1).干树枝闷烧烟尘中水溶性离子的平均总含量为(6.38±2.79)g·kg~(-1).Na~+、SO_4~(2-)、K~+、Cl~-是主要组分,其平均排放因子为101.1~245.7 mg·kg~(-1).绿树枝明燃烟尘中水溶性离子的平均总含量为(22.13±13.52)g·kg~(-1).SO_4~(2-)、Cl~-、K~+是主要组分,其平均排放因子为136.4~197.6 mg·kg~(-1).绿树枝闷燃烟尘中水溶性离子的平均总含量为(15.71±19.09)g·kg~(-1).Cl~-、SO_4~(2-)、Na~+是主要成分,其平均排放因子为298.6~869.1 mg·kg~(-1).两类树枝在每种燃烧条件下产生的烟尘中,Cl~-与K~+的含量均显著正相关.干树枝闷烧时Cl~-的排放因子与含水率显著正相关.燃烧条件、树种及含水率均对森林生物质烟尘中水溶性离子的组成及排放因子有明显的影响.这对估算大气中林火来源的污染物有参考意义.     

国内民用燃煤烟气中多环芳烃排放因子研究

模拟国内民用燃煤过程.确定燃煤排放烟气中PAHs的排放因子、PAHs在烟气气相与颗粒相之间的分配、特征排放谱以及不同燃烧方式的影响.结果表明:以15种母体PAHs加和计,燃煤排放因子的变化范围为71～882 mg·k8-1,排放因子和有毒PAHs组份排放量由高至低依次为烟煤、蜂窝煤和无烟煤,主要毒性成份存在于颗粒相中.PAH组份的气-固相分配比例与其饱和蒸汽压存在显著的正相关关系.燃煤类型和燃煤中挥发组份对烟气PAHs排放因子、气-固相分配以及排放谱分布具有决定性作用.另外,不同燃烧方式对燃煤排放因子也有一定影响,缺氧条件会导致排放系数升高.