Estimating terpene and terpenoid emissions from conifer oleoresin composition

Abstract

The following algorithm, which is based on the thermodynamics of nonelectrolyte partitioning, was developed to predict emission rates of terpenes and terpenoids from specific storage sites in conifers: E i = x or i γ or i p i o where E i is the emission rate (µg C gdw-1 h-1) and p° i is the vapor pressure (mm Hg) of the pure liquid terpene or terpenoid, respectively, and x i or and γ i or are the mole fraction and activity coefficient (on a Raoult's law convention), respectively, of the terpene and terpenoid in the oleoresin. Activity coefficients are calculated with Hansen solubility parameters that account for dispersive, polar, and H-bonding interactions of the solutes with the oleoresin matrix. Estimates of p° i at 25°C and molar enthalpies of vaporization are made with the SIMPOL.1 method and are used to estimate p° i at environmentally relevant temperatures. Estimated mixing ratios of terpenes and terpenols were comparatively higher above resin-acid-and monoterpene-rich oleoresins, respectively. The results indicated a greater affinity of terpenes and terpenols for the non-functionalized and carboxylic acid containing matrix through dispersive and H-bonding interactions, which are expressed in the emission algorithm by the activity coefficient. The correlation between measured emission rates of terpenes and terpenoids for Pinus strobus

Relation of leaf terpene contents to terpene emission profiles in Japanese cedar (Cryptomeria japonica)

“…We calculated vapor–liquid equilibria from the measured foliar terpene contents to estimate terpene vapor pressures (Flores & Doskey, 2015): where P i is the partial pressure (mmHg) of compound i in equilibrium with oleoresin; and are the mole fraction and activity coefficient, respectively, of the compound in the oleoresin; and is the vapor pressure (mmHg) of the pure liquid solute i in the oleoresin (explained two paragraphs below). The parameters were estimated as proposed by Flores and Doskey (2015). Values of were estimated by multiplying the measured foliar contents of terpenes by the neutral fraction of oleoresin of Japanese cedar.…”

“…We calculated vapor-liquid equilibria from the measured foliar terpene contents to estimate terpene vapor pressures (Flores & Doskey, 2015):…”

Scots pine resin and BVOC emissions in relation to tree water dynamics

“…If resin composition and monoterpene emissions correlate closely, resin sampling could be an easy and fast way to map the monoterpene emission variability within a population or species. For example, Flores & Doskey (2015) used information on resin composition and the different chemical characteristics of the resin compounds to estimate the emissions of terpenes and terpenoids from Pinus strobus shoots. This kind of information would be useful when the atmospheric chemistry models evolve to account for the diverse monoterpenes.…”

“…When modelling and quantifying the monoterpene emissions from conifers, even when considering the effects of resin composition (Flores and Doskey 2015), resin is often considered a passive pool from which the compounds evaporate in a temperature-dependent manner (e.g. Tingey 1980) also potentially affected by other variables, such as humidity (Tingey et al 1991;Llusià and Peñuelas 1999).…”

Temporal and Spatial Variation in Scots Pine Resin Pressure and Composition

“…Finally, although resin forms a large monoterpene pool, only a few studies have addressed its effect on monoterpene emissions from conifer trees and ecosystems (Haapanala et al, 2012;Kivimäenpää et al, 2012;Eller et al, 2013;Flores and Doskey, 2015;Rissanen et al, 2016). Understanding the variation in resin composition between trees and the effect of resin on monoterpene emissions at the tree level would help to interpret the tree-to-tree variation in monoterpene emissions.…”