Biogenic secondary organic aerosols: A review on formation mechanism, analytical challenges and environmental impacts

The review initiates with current state of information on the atmospheric reaction mechanism of biogenic volatile organic compounds (BVOCs) and its fate in the atmosphere. The plants release BVOCs, i.e., isoprene, monoterpenes, and sesquiterpenes, which form secondary organic aerosols (SOA) upon oxidation. These oxidation reactions are primarily influenced by solar radiations along with other meteorological parameters viz.; temperature and relative humidity, therefore, the chemistry behind SOA formation is different during day than the night time. The review throws light upon the day and nighttime formation mechanism of SOA, recent advancements in the analytical techniques available for the measurements, and its impact on the environment. Studies have revealed that day time SOA formation is dominated by OH and O-3, however, NOx initiated SOA production is dominated during night. The formation mechanism addresses that the gaseous products of VOCs are firstly formed and then partitioned over the pre-existing particles. New particle formation and biomass-derived aerosols are found to be responsible for enhanced SOA formation. 2-Dimensional gas chromatography-mass spectrometer (2D-GC/MS) is observed to be best for the analysis of organic aerosols. Radiative forcing (RF) SOA is observed to be a useful parameter to evaluate the environmental impacts of SOA and reviewed studies have shown mean RF in the ranges of -0.27 to +0.20 W m(-2). (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The review discusses the atmospheric reaction mechanism of BVOCs and the formation of secondary organic aerosols, highlighting differences between day and night in SOA formation. Daytime SOA formation is dominated by OH and O-3, while nighttime formation is dominated by NOx. Analytical techniques like 2D-GC/MS are essential for studying organic aerosols, and radiative forcing SOA is a useful parameter for evaluating environmental impacts.