Abstract
ABSTRACT Volatile organic compounds (VOC) are emitted by vegetation in response to different kinds of stress, such as herbivory, environmental conditions and air pollutants. The aim of this study was to identify the VOC emitted by seedlings of Croton floribundus (L.) Spreng. exposed to a polluted environment and analyze the relationship among classes of compounds emitted, ozone levels and changes in climate conditions. Two exposures were carried out, one in winter (June to August 2012) and another in summer (January to April 2013), in the Parque Estadual das Fontes do Ipiranga, city of São Paulo, São Paulo State, Brazil. We identified 26 compounds that are grouped into oxygenates, aromatics, monoterpenes and sesquiterpenes. The emission of sesquiterpenes was inhibited in summer, while those of the oxygenated and aromatic compounds were induced. The emission of volatiles was correlated to ozone levels (AOT 40). Our results suggest that the levels of atmospheric ozone detected in the summer can increase the induction of oxygenates and reduce the emission of monoterpenes in C. floribundus plants.
Highlights
Volatile organic compounds (VOC) emitted by biogenic sources have a key role in the atmospheric chemistry and exceed those of anthropogenic origin in order of magnitude (Guenther 1997)
We identified 26 volatile compounds emitted by the leaves of Croton floribundus during winter and summer, which belong to four different chemical classes: 12 oxygenated (OX), seven aromatic (AR), three monoterpenes (MT) and four sesqueterpenes (ST), as shown in table 2 and figure 1
The number of OX and AR compounds detected was higher in winter, the sum of the emission percentage of these compounds was higher in the summer
Summary
Volatile organic compounds (VOC) emitted by biogenic sources have a key role in the atmospheric chemistry and exceed those of anthropogenic origin in order of magnitude (Guenther 1997). Biogenic emissions comprise 90% of the organic compounds emitted annually and are considered as the major terrestrial source of carbon for the atmosphere (Niinemets et al 2010). Biogenic VOC are directly associated with climate change, because to some extent, they modify the global balance of atmospheric carbon (Fehsenfeld et al.1992). These VOCs induce photochemical processes in the atmosphere, forming products that feedback oxidant species such as ozone, and . The atmospheric concentrations of ozone and other air pollutants are sensitive to superficial VOC fluxes, which can lead to their either accumulation or reduction (Ciccioli 1993, Schirmer et al 2010)
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