The pollution characterization of black carbon aerosols in the southwest suburb of beijing from 2013 to 2019

Abstract

Multi-year monitoring of black carbon (BC) concentrations has been conducted for the period December 2012 to January 2020 in Beijing. Equivalent BC1 (EBC1) and equivalent BC2 (EBC2) were measured using an EEL43D black carbon meter (throughout the sampling period) and a multi-wavelength absorption black carbon instrument (MABI, July 2021 to January 2020), respectively. A series of harsh measures resulted in a gradual decreasing in EBC1 mass concentration, with an annual average value of 5.38 ± 3.22 μg m−3. EBC1 mass concentration reached the peak in winter during these seven years. EBC1 mass concentration exhibited statistically negative correlations with planetary boundary layer height (R = −0.4) and ventilation coefficient (R = −0.3). The local atmospheric parameters such as temperature, wind speed, relative humidity and visibility also showed inverse relationship with EBC1. EBC1 mass concentration is in a trough during the year with high cumulative rainfall, indicating the removal effect of rainfall on BC. The accuracy of the new MABI instrument was verified and the mass absorption coefficient was re-estimated. The results revealed the relative contribution of biomass burning to EBC2 was 45% (0.08–3.93 μg m−3) during study period. The fossil fuels and traffic emission were the dominating source of EBC2 in most of the months, but biomass burning contributes more to EBC2 during the winter heating period.