SEASONAL VARIATION AND CARCINOGENIC ASSESSMENT OF PARTICULATE POLYCYCLIC AROMATIC HYDROCARBONS IN SHANGHAI,CHINA

对上海市城区和郊区采集的64个总悬浮颗粒物(TSP)样品进行GC/MS分析,结果表明:全年PAHs浓度范围为2.25-221.6ng·m~(-3),并呈现明显的秋、冬季节高而夏季低的变化特征,且PAHs年平均值郊区稍微高于城区.多环芳烃中苯并(b+k)荧蒽、茚并(1,2,3-cd)芘、晕苯等化合物相对含量较高,四环以上的组分全年平均含量在90%以上.采用苯并(a)芘和苯并(a)芘等效质量浓度(BaPE)对上海市大气颗粒物中的PAHs进行致癌风险评价,BaP年均值在城区和郊区分别为2.57ng·m~(-3)和2.86ng·m~(-3),秋季BaP年均值超过了居民区标准限值(5.0ng·m~(-3)).BaPE在城区和郊区的年均浓度分别为5.82ng·m~(-3)和7.24ng·m~(-3),秋季污染最为严重

我国民用燃煤的黑碳排放及控制减排

我国被认为是最大的黑碳排放国,其中民用燃煤可能是最重要的排放源.由于黑碳排放因子(EF_(BC))的匮乏造成了我国黑碳排放量估算的巨大不确定性.在系列实验中,我们对13个不同成熟度的煤种分别以蜂窝煤和块煤散烧形式在相应炉灶中燃烧所产生的黑碳进行了研究.在此基础上,综合提出了一套关于民用燃煤的EF_(BC)数据.其中,无烟煤以蜂窝煤和块煤形式的EF_(BC)分别为0.004和0.007 g·kg~(-1);烟煤则分别为0.09和3.05 g·kg~(-1).在各种影响因素中,煤的成熟度对EF_(BC)的影响最显著,尤其是中等挥发份烟煤(MVB)明显高于其他煤种;燃烧形式的改进(即块煤的蜂窝煤化)可以将烟煤的EF_(BC)平均降低35倍.据此计算我国2000年民用燃煤的黑碳排放量为94千吨,明显低于前人的估算结果;其中烟煤的块状散烧贡献最大,占90%以上.从控制减排的角度,如果禁止MVB作为民用燃料,并进一步普及使用蜂窝煤,民用燃煤的黑碳排放量可减少80%以上,我国的黑碳排放问题在很大程度上得以控制

A Preliminary Study on Brown Carbon Emissions from Open Agricultural Biomass Burning and Residential Coal Combustion in China

近年来的研究表明,在BC(黑碳)和OC(有机碳)之间,还存在着一种有弱吸光能力的OC,因大多显棕黄色而被称为BrC (brown carbon,棕色碳). 广泛存在的秸杆焚烧和冬季大量民用燃煤的使用,使国内BrC 排放严重,但鲜见对其排放量的测算. 采用七波段黑碳仪(aethalometer)方法,对夏季小麦秸杆焚烧过程及冬季民用炉燃煤过程产生的烟气进行现场监测,根据BrC 与BC的光谱关联性差别,分化出R_(BrC/BC)(总光学衰减中BrC和BC的相对贡献). 结果表明: 麦秆焚烧和民用燃煤烟气的R_(BrC/BC)分别为1. 754 ± 0. 278和0. 183 ± 0. 142. 借助R_(BrC/BC)值,结合现有的BC 排放清单(2000年),初步推算出中国民用燃煤和秸杆田间焚烧 BrC的排放总量(以BC 当量计,下同)为(270. 6 ± 101. 6)Gg,接近同期BC 排放量的一半; 其中秸杆焚烧的BrC 排放量为(175. 4 ± 27. 8)Gg,约占二者总量的65%; 民用燃煤的BrC 排放量为(95. 2 ± 73. 7)Gg,约占35%. 该研究结果可为更全面的BrC 排放测算奠定基础,并为研究BrC的大气化学及辐射强迫提供依据

Study of the Details of Aerosol Carbon Measurements in Autumn and Winter in Beijing

Quantitative studies on carbonaceous aerosols are based on individual bulk values of organic carbon (OC) and elemental carbon (EC) or black carbon (BC),yet few cases of in-depth interpretation of the minutiae of the measurement results are available,making full understanding and application of the information involved in instrument analysis results difficult. In October 2015 (autumn) and January 2016 (winter),rho (OC) and rho (EC) in PM_(2. 5) of Beijing were measured using the thermal/optical IMPROVE_A protocol (model 2001A), and meantime rho (BC) was measured using the optical aethalometer method (AE31). The results showed that: (1) The rho (OC) and rho (EC) in autumn were 8. 59 and 3. 89 mug/m~3,respectively, and those in winter were 16. 45 and 6. 19 mug/m~3,respectively. The values in winter were significantly higher than those in autumn. (2) The average value of rho (OC_1 ) /rho (OC) ratio in autumn samples analyzed by thermal/optical method was 0. 08 0. 04,and in winter samples,the ratio rose to 0. 22 0. 05,which may be a result of higher emissions of volatile organic compounds (VOCs) and subsequent condensation in lower ambient temperatures in winter. (3) Regarding the determination results of the 7-wavelength aethalometer,the ratio of BC equivalent measured at 370 nm (rho (BC370 ) ) to the standard BC measured at 880 nm (rho (BC880) ),i. e.,rho (BC370) /rho (BC880),was 1. 05 0. 11 in autumn,indicative of weak optical absorption by brown carbon (BrC) in that season,but jumped to 1. 47 0. 11 in winter,40% higher than that of autumn. (4) The variation trends of rho (BC) /rho (EC) and rho (PM_(2. 5) ) were very similar,implying an increased chance of core-shell internal mixing and a consequent enhancement of EC's mass absorption efficiency (MAE). rho (BC) values reported by the aethalometer were thus magnified,leading to a bigger rho (BC) /rho (EC) ratio. However,further investigation showed that the increase reached a'platform'when rho (PM_(2. 5) ) reached 50-70 mug/m~3,with an'autumn platform value'at around 1. 05 and a'winter platform value'at around 0. 55. It could be seen that the measurement results of the instruments contain a large amount of information,some of which has usually been ignored in routine practice. The in-depth interpretation of the details of the information helps better understand the comprehensive characteristics of carbonaceous aerosols

Measurement of Brown Carbon Emission Factors for HouseholdUse of Coal And Biomass in China

棕色碳(brown carbon,Br C)即吸光有机碳,因其吸光效应对全球气候变化、区域能见度、人体健康等影响而备受关注。我国是化石燃料和生物质燃料消耗大国,在居民生活领域每年有大量的煤炭和生物质燃料的使用,但目前尚没有相应的Br C排放因子(EFBr C)的实测数据。该研究通过七波段黑碳仪对农村冬季居民生活用煤和生物质燃烧产生的烟气进行现场实测研究,利用Br C和黑碳(BC)吸光波长指数(魡)的差异,计算二者比值(RBr C/BC),并结合碳平衡法测得的黑碳排放因子(EFBC)计算EFBr C;利用我国2000年居民生活用燃煤和生物质燃料的使用量,进而初步估算我国Br C的排放量。结果表明..

中国秸杆焚烧及民用燃煤棕色碳排放的初步研究

近年来的研究表明,在BC(黑碳)和OC(有机碳)之间,还存在着一种有弱吸光能力的OC,因大多显棕黄色而被称为BrC (brown carbon,棕色碳). 广泛存在的秸杆焚烧和冬季大量民用燃煤的使用,使国内BrC 排放严重,但鲜见对其排放量的测算. 采用七波段黑碳仪(aethalometer)方法,对夏季小麦秸杆焚烧过程及冬季民用炉燃煤过程产生的烟气进行现场监测,根据BrC 与BC的光谱关联性差别,分化出R_(BrC/BC)(总光学衰减中BrC和BC的相对贡献). 结果表明: 麦秆焚烧和民用燃煤烟气的R_(BrC/BC)分别为1. 754 ± 0. 278和0. 183 ± 0. 142. 借助R_(BrC/BC)值,结合现有的BC 排放清单(2000年),初步推算出中国民用燃煤和秸杆田间焚烧 BrC的排放总量(以BC 当量计,下同)为(270. 6 ± 101. 6)Gg,接近同期BC 排放量的一半; 其中秸杆焚烧的BrC 排放量为(175. 4 ± 27. 8)Gg,约占二者总量的65%; 民用燃煤的BrC 排放量为(95. 2 ± 73. 7)Gg,约占35%. 该研究结果可为更全面的BrC 排放测算奠定基础,并为研究BrC的大气化学及辐射强迫提供依据