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Within‐plant isoprene oxidation confirmed by direct emissions of oxidation products methyl vinyl ketone and methacrolein
Author(s) -
Jardine Kolby J.,
Monson Russell K.,
Abrell Leif,
Saleska Scott R.,
Arneth Almut,
Jardine Angela,
Ishida Françoise Yoko,
Serrano Ana Maria Yanez,
Artaxo Paulo,
Karl Thomas,
Fares Silvano,
Goldstein Allen,
Loreto Francesco,
Huxman Travis
Publication year - 2012
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2011.02610.x
Subject(s) - isoprene , methacrolein , methyl vinyl ketone , chemistry , environmental chemistry , green leaf volatiles , volatile organic compound , ozone , atmospheric chemistry , organic chemistry , botany , catalysis , polymerization , herbivore , copolymer , biology , methacrylic acid , polymer
Isoprene is emitted from many terrestrial plants at high rates, accounting for an estimated 1/3 of annual global volatile organic compound emissions from all anthropogenic and biogenic sources combined. Through rapid photooxidation reactions in the atmosphere, isoprene is converted to a variety of oxidized hydrocarbons, providing higher order reactants for the production of organic nitrates and tropospheric ozone, reducing the availability of oxidants for the breakdown of radiatively active trace gases such as methane, and potentially producing hygroscopic particles that act as effective cloud condensation nuclei. However, the functional basis for plant production of isoprene remains elusive. It has been hypothesized that in the cell isoprene mitigates oxidative damage during the stress‐induced accumulation of reactive oxygen species ( ROS ), but the products of isoprene‐ ROS reactions in plants have not been detected. Using pyruvate‐2‐ 13 C leaf and branch feeding and individual branch and whole mesocosm flux studies, we present evidence that isoprene ( i ) is oxidized to methyl vinyl ketone and methacrolein ( i ox ) in leaves and that i ox /i emission ratios increase with temperature, possibly due to an increase in ROS production under high temperature and light stress. In a primary rainforest in A mazonia, we inferred significant in plant isoprene oxidation (despite the strong masking effect of simultaneous atmospheric oxidation), from its influence on the vertical distribution of i ox uptake fluxes, which were shifted to low isoprene emitting regions of the canopy. These observations suggest that carbon investment in isoprene production is larger than that inferred from emissions alone and that models of tropospheric chemistry and biota–chemistry–climate interactions should incorporate isoprene oxidation within both the biosphere and the atmosphere with potential implications for better understanding both the oxidizing power of the troposphere and forest response to climate change.