Biotic stress: a significant contributor to organic aerosol in Europe?

Abstract

Abstract. We have investigated the potential impact on organic aerosol formation from biotic stress-induced emissions (SIE) of organic molecules from forests in Europe (north of lat. 45 • N). Emission estimates for sesquiterpenes (SQT), methyl salicylate (MeSA) and unsaturated C 17 compounds, due to different stressors, are based on experiments in the Jülich Plant Atmosphere Chamber (JPAC), combined with estimates of the fraction of stressed trees in Europe based on reported observed tree damage. SIE were introduced in the EMEP MSC-W chemical transport model and secondary organic aerosol (SOA) yields from the SIE were taken from the JPAC experiments. Based on estimates of current levels of infestation and the JPAC aerosol yields, the model results suggest that the contribution to SOA in large parts of Europe may be substantial. It is possible that SIE contributes as much, or more, to organic aerosol than the constitutive biogenic VOC emissions, at least during some periods. Based on the assumptions in this study, SIE-SOA are estimated to constitute between 50 and 70 % of the total biogenic SOA (BSOA) in a current-situation scenario where the biotic stress in northern and central European forests causes large SIE of MeSA and SQT. An alternative current-situation scenario with lower SIE, consisting solely of SQT, leads to lower SIE-SOA, between 20 and 40 % of the total BSOA.Hypothetical future scenarios with increased SIE, due to higher degrees of biotic stress, show that SOA formation due to SIE can become even larger.Unsaturated C 17 BVOC (biogenic volatile organic compounds) emitted by spruce infested by the forest-honey generating bark louse, Cinara pilicornis, have a high SOAforming potential. A model scenario investigating the effect of a regional, episodic infestation of Cinara pilicornis in Baden-Württemberg, corresponding to a year with high production of forest honey, shows that these types of events could lead to very large organic aerosol formation in the infested region.We have used the best available laboratory data on biotic SIE applicable to northern and central European forests. Using these data and associated assumptions, we have shown that SIE are potentially important for SOA formation but the magnitude of the impact is uncertain and needs to be constrained by further laboratory, field and modelling studies. As an example, the MeSA, which is released as a consequence of various types of biotic stress, is found to have a potentially large impact on SIE-SOA in Europe, but different assumptions regarding the nighttime chemistry of MeSA can change its SOA potential substantially. Thus, further investigations of the atmospheric chemistry of MeSA and observational field studies are needed to clarify the role of this compound in the atmosphere.

Long-term measurements (2010–2014) of carbonaceous aerosol and carbon monoxide at the Zotino Tall Tower Observatory (ZOTTO) in central Siberia

“…As temperatures increase, population outbreaks of tree-damaging insects can occur more frequently. The emissions of organic substances from damaged trees are significantly higher than from healthy trees (Bergström et al, 2014). For example, in the boreal environment, trees damaged by the pine borer (Neodiprion sertifer) emit 11 times more monoterpenes and 20 times more sesquiterpenes compared to healthy trees.…”

Simulating secondary organic aerosol from missing diesel-related intermediate-volatility organic compound emissions during the Clean Air for London (ClearfLo) campaign

“…In some cases, this underestimation has been shown to be due to problems with the underlying emission inventories, particularly for domestic wood burning in wintertime (Simpson et al, 2007;Denier van der Gon et al, 2015). There may also be sources of biogenic secondary organic aerosol (BSOA) arising from previously neglected VOC emissions such as those induced by biotic stress (Berg et al, 2013;Bergström et al, 2014).…”

<sup>13</sup>C labelling study of constitutive and stress-induced terpenoide missions from Norway spruce and Scots pine

“…They cause higher release of carbon back into the atmosphere and thus strongly affect the carbon 5 balance of ecosystem. The stress-induced emissions are also important for secondary organic aerosol formation (Mentel et al, 2013;Bergström et al, 2014) and cloud droplet formation (Zhao et al, 2017). Thus, they also influence air quality and climate.…”