Plant-derived Secondary Organic Material in the Air and Ecosystems

Oxidation of biogenic and anthropogenic VOCs in the atmosphere leads to formation of SOA particles which further grow and participate in cloud formation, and affect solar irradiation, temperature, and precipitation. Part of the atmospheric SOA also accumulates as SOM on foliage of plants and deposits on soil surface. Biogenic VOCs are emitted at high rates from plant foliage, but SOM formation under conditions found in the leaf boundary layer is unexplored. The ecological and evolutionary effects of biogenic VOCs may persist even after the original VOCs are oxidized. SOM formed from plant VOCs are expected to have even stronger ecological effects than the parent VOCs as these oxidation products are decorated with a number of reactive functional groups (carbonyls, carboxyls, hydroxyls, peroxy, hemiacetal, etc.) which may affect, for example, sensory organs of herbivores. Biogenic secondary organic aerosol (SOA) and deposited secondary organic material (SOM) are formed by oxidation of volatile organic compounds (VOCs) emitted by plants. Many SOA compounds have much longer chemical lifetimes than the original VOC, and may accumulate on plant surfaces and in soil as SOM because of their low volatility. This suggests that they may have important and presently unrecognized roles in plant adaptation. Using reactive plant terpenoids as a model we propose a three-tier (atmosphere–vegetation–soil) framework to better understand the ecological and evolutionary functions of SOM. In this framework, SOA in the atmosphere is known to affect solar radiation, SOM on the plant surfaces influences the interactive organisms, and wet and dry deposition of SOM on soil affects soil organisms. Biogenic secondary organic aerosol (SOA) and deposited secondary organic material (SOM) are formed by oxidation of volatile organic compounds (VOCs) emitted by plants. Many SOA compounds have much longer chemical lifetimes than the original VOC, and may accumulate on plant surfaces and in soil as SOM because of their low volatility. This suggests that they may have important and presently unrecognized roles in plant adaptation. Using reactive plant terpenoids as a model we propose a three-tier (atmosphere–vegetation–soil) framework to better understand the ecological and evolutionary functions of SOM. In this framework, SOA in the atmosphere is known to affect solar radiation, SOM on the plant surfaces influences the interactive organisms, and wet and dry deposition of SOM on soil affects soil organisms. various chemical processes, often driven by sunlight, which slowly occur in SOM and change its chemical composition. Aging finally leads to full degradation of SOM and emissions of volatile products such as formic acid. aerosol particles, typically over 100 nm in size, on which water vapor condenses to form cloud droplets. a bouquet of plant volatiles emitted after plant tissue damage by a herbivore. Constitutively emitted VOCs are emitted at higher rates after the damage, and emissions of several other compounds are induced. Typical compounds are 6-carbon green leaf volatiles including aldehydes, esters, and alcohols released after mechanical damage to plant cell membranes. primary organic aerosol represents organic particles emitted from biogenic (fungal spores, plant debris, wildfires) or anthropogenic (fossil fuel combustion, biomass burning) sources. consisting of particulate matter and gaseous species produced by oxidation of various biogenic and anthropogenic VOCs in air. containing low volatility SOA compounds that accumulate in condensed phase including SOA particles and films on surfaces of plants and on other objects. (Not to be confused with soil organic matter, which has the same abbreviation in the current literature.) compounds derived from one or more isoprene units (C5H8), including monoterpenes (C10H16), sesquiterpenes (C15H24), and their numerous derivatives. Many VOCs emitted by plants belong to the terpenoid family. emitted from biogenic (plants, animals, microbes) or anthropogenic (fossil fuel production and use, biomass burning) sources. VOCs synthesized by plants have various functions in plant physiology, and when emitted, they have various ecological purposes, for example, to repel herbivores or attract pollinators.