The research hotspots and trends of volatile organic compound emissions from anthropogenic and natural sources: A systematic quantitative review br

Volatile organic compound (VOC) emissions have attracted wide attention due to their impacts on atmospheric quality and public health. However, most studies reviewed certain aspects of natural VOCs (NVOCs) or anthropogenic VOCs (AVOCs) rather than comprehensively quantifying the hotspots and evolution trends of AVOCs and NVOCs. We combined the bibliometric method with the evolution tree and Markov chain to identify research focus and uncover the trends in VOC emission sources. This study found that research mainly focused on VOC emission characteristics, effects on air quality and health, and VOC emissions under climate change. More studies concerned on AVOCs than on NVOCs, and AVOC emissions have shifted with a decreasing proportion of transport emissions and an increasing share of solvent utilization in countries with high emissions and publi-cations (China and the USA). Research on AVOCs is imperative to develop efficient and economical abatement techniques specific to solvent sources or BTEX species to mitigate the detrimental effects. Research on NVOCs originating from human sources risen due to their application in medicine, while studies on sources sensitive to climate change grew slowly, including plants, biomass burning, microbes, soil and oceans. Research on the long-term responses of NVOCs derived from various sources to climate warming is warranted to explore the evolution of emissions and the feedback on global climate. It is worthwhile to establish an emission inventory with all kinds of sources, accurate estimation, high spatial and temporal resolution to capture the emission trends in the synergy of industrialization and climate change as well as to simulate the effects on air quality. We review VOC emissions from both anthropogenic and natural sources under climate change and their effects on atmospheric quality and health to point out the research directions for the comprehensive control of global VOCs and miti-gation of O3 pollution.

Automated summary

This study used the bibliometric method, evolution tree, and Markov chain to identify the research focus and trends in volatile organic compound (VOC) emissions. The results showed that the research primarily focused on VOC emission characteristics, effects on air quality and health, and VOC emissions under climate change. There was more research on anthropogenic VOCs (AVOCs) compared to natural VOCs (NVOCs), with AVOC emissions shifting towards a decreasing proportion of transport emissions and an increasing share of solvent utilization in high-emission and high-publication countries like China and the USA. Additionally, the study found a growing research interest in NVOCs from human sources, while research on sources sensitive to climate change, such as plants, biomass burning, microbes, soil, and oceans, grew slowly. Establishing an emission inventory with accurate estimation, high spatial and temporal resolution is important to capture emission trends and simulate the effects on air quality under industrialization and climate change. Overall, this study emphasizes the importance of comprehensive control of global VOCs and mitigation of O3 pollution.