1Yale-NUIST Center on Atmospheric Environment, Joint International Research Laboratory of Climate and Environment Change (ILCEC), Nanjing University of Information Science and Technology, Nanjing 210044, China
2Key Laboratory of Meteorological Disaster Ministry of Education (KLME), Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science and Technology, Nanjing 210044, China
3School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
4School of Forestry and Environmen tal Studies, Yale University, New Haven 06511, USA
5Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing 100084, China
6Joint Center for Global Change Studies (JCGCS), Beijing 100084, China
7Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokohama 236-0001, Japan
1Yale-NUIST Center on Atmospheric Environment, Joint International Research Laboratory of Climate and Environment Change (ILCEC), Nanjing University of Information Science and Technology, Nanjing 210044, China
2Key Laboratory of Meteorological Disaster Ministry of Education (KLME), Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science and Technology, Nanjing 210044, China
3School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
4School of Forestry and Environmen tal Studies, Yale University, New Haven 06511, USA
5Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing 100084, China
6Joint Center for Global Change Studies (JCGCS), Beijing 100084, China
7Research and Development Center for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokohama 236-0001, Japan
Received: 01 Oct 2018 – Accepted for review: 12 Jan 2019 – Discussion started: 15 Jan 2019
Abstract. Biomass burning can significantly impact the chemical and optical properties of carbonaceous aerosols. Here, the impacts of biomass burning emissions on chemical and optical properties of carbonaceous aerosols were studied during wintertime in a megacity of Nanjing, East China. The high abundance of biomass burning tracers such as levoglucosan (lev), mannosan (man), galactosan (gal) and non-sea-salt potassium (nss-K+) was found during the studied period with the concentration ranges of 22.4–1476 ng m−3, 2.1–56.2 ng m−3, 1.4–32.2 ng m−3, and 0.2–3.8 μg m−3, respectively. Backward air mass origin analysis, potential emission sensitivity of element carbon (EC), and MODIS fire spot information indicated that the elevations of the carbonaceous aerosols were due to the transported biomass-burning aerosols from Southeast China. The characteristic mass ratio maps of lev/man and lev/nss-K+ suggested that the biomass fuels were mainly crop residuals. Furthermore, the strong correlation (p < 0.01) between biomass burning tracers (e.g. lev) and light absorption coefficient (babs) for water soluble organic carbon (WSOC) revealed that biomass burning emissions played a significant role in the light-absorption properties of carbonaceous aerosols. The solar energy absorption due to water-soluble brown carbon (BrC) and EC was estimated by the calculation-based on measured light-absorbing parameters and the simulation-based on a radiative transfer model (RRTMG_SW). The solar energy absorption of water-soluble BrC in short wavelengths (300–400 nm) was 0.8 ± 0.4 (0.2–2.3) W m−2 from the calculation-based and 1.2 ± 0.5 (0.3–1.9) W m−2 from the RRTMG_SW model. The absorption capacity of water-soluble BrC accounted for about 20–30 % of the total absorption of EC aerosols. The solar energy absorption of WSOC due to biomass burning was estimated as 0.2 ± 0.1 (0.0–0.9) W m−2. Potential Source Contribution Function model simulations showed that the solar energy absorption induced by WSOC and EC aerosols was mostly due to the regional transported carbonaceous aerosols from the source regions such as southeast China. Our results illustrate the importance of the absorbing water-soluble brown carbon aerosols in trapping additional solar energy in the low-level atmosphere, heating the surface and inhibiting the energy from escaping the atmosphere. The regional transported biomass burning emissions may significantly impact the chemical and optical properties of carbonaceous aerosols in the polluted atmosphere.
Although a total ban of straw burning has been enforced in east China, the regional-transported biomass burning emissions remarkably impacted the chemical and optical properties of carbonaceous aerosols in Nanjing, which were quantified by the calculation based on measured data and the simulation based on model. The results showed that regional-transported biomass burning emissions significantly contributed to the carbonaceous aerosols and impacted the solar radiation balance of the atmosphere.
Although a total ban of straw burning has been enforced in east China, the regional-transported...