title: Important fossil source contribution to brown carbon in Beijing during winter.
abstract: Organic aerosol (OA) constitutes a substantial fraction of fine particles and affects both human health and climate. It is becoming clear that OA absorbs light substantially (hence termed Brown Carbon, BrC), adding uncertainties to global aerosol radiative forcing estimations. The few current radiative-transfer and chemical-transport models that include BrC primarily consider sources from biogenic and biomass combustion. However, radiocarbon fingerprinting here clearly indicates that light-absorbing organic carbon in winter Beijing, the capital of China, is mainly due to fossil sources, which contribute the largest part to organic carbon (OC, 67 ± 3%) and its sub-constituents (water-soluble OC, WSOC: 54 ± 4%, and water-insoluble OC, WIOC: 73 ± 3%). The dual-isotope (Δ14C/δ13C) signatures, organic molecular tracers and Beijing-tailored emission inventory identify that this fossil source is primarily from coal combustion activities in winter, especially from the residential sector. Source testing on Chinese residential coal combustion provides direct evidence that intensive coal combustion could contribute to increased light-absorptivity of ambient BrC in Beijing winter. Coal combustion is an important source to BrC in regions such as northern China, especially during the winter season. Future modeling of OA radiative forcing should consider the importance of both biomass and fossil sources.
authors.affiliation: SKL-ESPC and BIC-ESAT, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
authors.forename: Caiqing
authors.initials: C
authors.lastname: Yan
authors.affiliation: SKL-ESPC and BIC-ESAT, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Zheng
authors.affiliation: Department of Environmental Science and Analytical Chemistry (ACES) and the Bolin Centre for Climate Research, Stockholm University, Stockholm 10691, Sweden.
authors.forename: Carme
authors.initials: C
authors.lastname: Bosch
authors.affiliation: Department of Environmental Science and Analytical Chemistry (ACES) and the Bolin Centre for Climate Research, Stockholm University, Stockholm 10691, Sweden.
authors.forename: August
authors.initials: A
authors.lastname: Andersson
authors.affiliation: Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: Yury
authors.initials: Y
authors.lastname: Desyaterik
authors.affiliation: Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: Amy P
authors.initials: AP
authors.lastname: Sullivan
authors.affiliation: Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Collett
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Shuxiao
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
authors.forename: Kebin
authors.initials: K
authors.lastname: He
authors.affiliation: Department of Environmental Science and Analytical Chemistry (ACES) and the Bolin Centre for Climate Research, Stockholm University, Stockholm 10691, Sweden.
authors.forename: Örjan
authors.initials: Ö
authors.lastname: Gustafsson