Increases in Biogenic Volatile Organic Compound Concentrations Observed after Rains at Six Forest Sites in Non-Summer Periods

Takafumi Miyama,Michiaki Okano,Katsumi Yamanoi,Hironori Noguchi,Yukio Yasuda,Tomoaki Morishita,Yasuko Mizoguchi,Yuji Kominami,Kenzo Kitamura,Satoru Takanashi,Natsuko Yoshifuji,Kazuho Matsumoto

doi:10.3390/atmos11121381

Abstract

Since biogenic volatile organic compounds (BVOCs) are important precursors of ozone, the monitoring of the BVOC concentration distributions is needed. In general, forest BVOC concentrations increase in summer as well as in other seasons. This study aims to detect temporally sporadic increases in BVOC concentrations in the non-summer months and to analyze the occurring climatic conditions. Using a uniform sampling system and shared gas chromatography–mass spectrometry, the concentrations of isoprene and monoterpenes in six Japanese forests were observed approximately once a month for 3 years. Using the observed data, the relations between the BVOC concentration increases and meteorological factors were evaluated. Twenty instances of temporal increases in BVOC concentrations were observed. These mainly occurred in spring for isoprene and in autumn for monoterpenes. Most of the increases in the non-summer months were observed after a rainfall event, when the daily temperature range was large, suggesting that wind, rain, and a rapid diurnal temperature rise could be factors in the non-summer months. Thus, the network monitoring of BVOC concentrations might be effective for understanding the effects of factors other than temperature, and the mechanisms and frequency of the temporal increases, on the BVOC concentrations in various forests.

Highlights

Forests are a large source of biogenic volatile organic compounds (BVOCs) in terrestrial ecosystems.Globally, BVOC emissions are estimated to be much higher than the anthropogenic volatile organic compound (AVOC) emissions [1]
Most measurements of BVOC concentrations have been conducted in suburban forests and not in deep forests; uncertainty remains regarding the spatial distribution and temporal variation of BVOCs around forests
Twenty data items for high BVOC concentrations observed in the non-summer months were numbered

Summary

Introduction

Forests are a large source of biogenic volatile organic compounds (BVOCs) in terrestrial ecosystems. BVOC emissions are estimated to be much higher than the anthropogenic volatile organic compound (AVOC) emissions [1]. Atmosphere 2020, 11, 1381 ozone [2,3,4] and secondary organic aerosols (SOAs) [5]. High surface ozone concentration could harm human health and decreases crop yields [6]. In Japan in particular, high ozone concentrations have been observed around forests in recent years, which might be due to the BVOC emissions from forests. Recent simulation studies have shown that the use of a gridded database to estimate the BVOC emissions throughout Japan has led to significant differences in the ozone concentrations in air quality simulations [7,8]. Most measurements of BVOC concentrations have been conducted in suburban forests and not in deep forests; uncertainty remains regarding the spatial distribution and temporal variation of BVOCs around forests

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