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..