Emission of sunscreen salicylic esters from desert vegetation and their contribution to aerosol formation

Abstract

Abstract. Biogenic volatile organic compounds (BVOC) produced by plants are known to have an important role in atmospheric chemistry. However, our knowledge of the range of BVOCs produced by different plant processes is still expanding, and there remain poorly understood categories of BVOCs. In this study, emissions of a novel class of BVOC emissions were investigated in a desert region. Our study considered 8 species of common desert plants: blackbrush (Coleogyne ramosissima), desert willow (Chilopsis linearis), mesquite (Prosopis glandulosa), mondel pine (Pinus eldarica), pinyon pine (Pinus monophylla), cottonwood (Populus deltoides), saguaro cactus (Carnegiea gigantea) and yucca (Yucca baccata). The measurements focused on BVOCs with relatively high molecular weight (>C 15 ) and/or an oxygenated functional group. Significantly high emission rates of two salicylic esters were found for blackbrush, desert willow and mesquite with emission rates of 3.1, 1.0 and 4.8µgC dwg −1 h −1 , respectively (dwg; dry weight of the leaves in gram). The salicylic esters were identified as 2-ethylhexenyl salicylate (2-EHS) and 3,3,5-trimethylcyclohexenyl salicylate (homosalate) and are known as effective ultraviolet (UV) absorbers. We propose that the plants derive a protective benefit against UV radiation from the salicylic esters and that the emission process is driven by the physical evaporation of the salicylic esters due to the high ambient temperatures. In addition, the salicylic esters are predicted to be an effective precursor of secondary organic aerosol (SOA) because they probably produce oxidation products that can condense onto the aerosol phase. We estimated the contribution of the sunscreen esters themselves and their oxidation products on the SOA formation for the Las Vegas area using a BVOC emission model. The contribution was estimated to reach 50% of the biogenic terpenoid Correspondence to: Sou Matsunaga (sou@tmu.ac.jp) emission in the landscapes dominated by desert willow and mesquite and 13% in the Las Vegas area. The contributions to biogenic SOA are likely to be higher due to the potentially high SOA yields of these compounds.

The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1): an extended and updated framework for modeling biogenic emissions

“…Shim et al (2007) used inverse modeling to estimate global average biogenic emissions of hydrogen cyanide which is emitted from thousands of plant species, including many economically important food plants, when they are wounded. Matsunaga et al (2008) observed significant emissions of the "sunscreen" compounds, homosalate (C 16 H 22 O 3 ) and 2-ethylhexyl salicylate [also known as octyl salate] (C 15 H 22 O 3 ), from Mojave desert plants and much lower emissions from temperate forest tree species. They were the major BVOC emission observed from mesquite (Prosopis spp.)…”

Estimations of isoprenoid emission capacity from enclosure studies: measurements, data processing, quality and standardized measurement protocols

“…Among polymers, physico-chemical properties for VOC system construction are generally suitable for rigid polymers with low amorphous phase (high crystalline phase) fraction such as fluorinated hydrocarbons -PFA (perfluoroalkoxy), FEP (fluorinated ethylene propylen), and PTFE brands (e.g. Teflon ® and Chemfluor ® ) (Geosyntec consultants Inc. For gas exchange enclosures (cuvettes), glass, although fragile, typically has very low adsorption capacity for most VOCs and therefore has been used in many sampling systems (Beauchamp et al, 2005;Copolovici et al, 2011;Copolovici and Niinemets, 2010;Fuentes et al, 1995;Hüve et al, 2007;Matsunaga et al, 2008;Papiez et al, 2009;Rasulov et al, 2009a;Wildt et al, 2003). Glass cuvettes without (Beauchamp et al, 2005;Copolovici et al, 2011;Hüve et al, 2007;Wildt et al, 2003) and with temperature control have been used (Fig.…”

“…Glass cuvettes without (Beauchamp et al, 2005;Copolovici et al, 2011;Hüve et al, 2007;Wildt et al, 2003) and with temperature control have been used (Fig. 1a, b, Copolovici and Niinemets, 2010;Matsunaga et al, 2008;Papiez et al, 2009;Rasulov et al, 2009a). Cuvettes made of stainless steel with glass windows and polymer seals have also been found to have satisfactory terpenoid recovery, although memory effects leading to long equilibration times have been noted as a major disadvantage (Helmig et al, 2004).…”

“…Among recommended polymers for sampling are transparent fluorinated hydrocarbon films -like FEP and PFA, or opal PTFE (Teflon ® ), PVF (polyvinylfluoride, Tedlar ® ), PVDF (polyvinylidenfluoride, Kynar ® , Dyneon ® , Solef ® ) (e.g. Kesselmeier et al, 1993Kesselmeier et al, , 1996Matsunaga et al, 2008;Niinemets et al, 2002a;Pape et al, 2009;Steinbrecher and Hauff, 1996). In addition, "polyester" (polyethylene terephthalate, PETE) films such as Mylar ® , and Nylon-6 films (so-called "cooking bags") have been often used in chemical ecology (Raguso et al, 2003;Stewart-Jones and Poppy, 2006;Theis, 2006).…”

Synthesis of esters derived from 2,3,4-tri-O-benzyl-alpha-D-methylglucoside

“…Salicylate esters display immunity against other organisms 1,2 in plants, regeneration effects 3 and possibly a protective effect against UV radiation in plants. 4 Synthetic salicylic acid derivatives are well known as biological active compounds such as analgesic and antifungal 5 and are also part of cosmetic formulations. 6 Some recent works refer to application of salicylic esters and salicylic acid-based dendrimers as potential drug carriers.…”