Ice core records of monoterpene- and isoprene-SOA tracers from Aurora Peak in Alaska since 1660s: Implication for climate change variability in the North Pacific Rim

Abstract

19Monoterpene and isoprene secondary organic aerosol (SOA) tracers are reported for the 20 first time in an Alaskan ice core to better understand the biological source strength before and 21 after the industrial revolution in the Northern Hemisphere. We found significantly high 22 concentrations of monoterpene-and isoprene-SOA tracers (e.g., pinic, pinonic, and 2-23 methylglyceric acids, 2-methylthreitol and 2-methylerythritol) in the ice core, which show 24 historical trends with good correlation to each other since 1660s. They show positive 25 correlations with sugar compounds (e.g., mannitol, fructose, glucose, inositol and sucrose), and 26anti-correlations with α-dicarbonyls (glyoxal and methylglyoxal) and fatty acids (e.g., C 18:1 ) in 27 the same ice core. These results suggest similar sources and transport pathways for 28 monoterpene-and isoprene-SOA tracers. In addition, we found that concentrations of C 5 -29 alkene triols (e.g., 3-methyl-2,3,4-trihydroxy-1-butene, cis-2-methyl 1,3,4-trihydroxy-1-butene 30 and trans-2-methyl-1,3,4-trihydroxy-1-butene) in the ice core have increased after the Great 31 Pacific Climate Shift (late 1970s). They show positive correlations with α-dicarbonyls and 32 fatty acids (e.g., C 18:1 ) in the ice core, suggesting that enhanced oceanic emissions of biogenic 33 organic compounds through the marine boundary layer are recorded in the ice core from 34 Alaska. Photochemical oxidation process for these monoterpene-and isoprene-/sesquiterpene-35 SOA tracers are suggested to be linked with the periodicity of multi-decadal climate 36 oscillations and retreat of sea ice in the Northern Hemisphere. 37 38

Organic Compounds in a Sub‐Antarctic Ice Core: A Potential Suite of Sea Ice Markers

“…Giorio et al () identified two groups of organic compounds which showed promise as marine‐sourced biomarkers in ice cores: fatty acids and secondary oxidation aerosols (SOA) of terpenes. A few existing studies find examples of these compounds in Greenland (Kawamura, Suzuki, et al, ) and Alaskan ice core records (Pokhrel, Kawamura, Ono, et al, ; Pokhrel, Kawamura, Seki, et al, ) over time scales of hundreds of years, with concentrations linked to both changing emission quantities and the strength and direction of atmospheric transport pathways.…”

“…Giorio et al (2018) identified two groups of organic compounds which showed promise as marine-sourced biomarkers in ice cores: fatty acids and secondary oxidation aerosols (SOA) of terpenes. A few existing studies find examples of these compounds in Greenland (Kawamura, Suzuki, et al, 1996) and Alaskan ice core records (Pokhrel, Kawamura, Ono, et al, 2015; over time scales of ©2019. The Authors.…”

Photooxidation of cyclohexene in the presence of SO<sub>2</sub>: SOA yield and chemical composition

“…SOA formation from the oxidation of VOCs has been receiving significant attention in recent years due to its large implication in the formation of atmospheric fine particulate matter (Jimenez et al, 2009). SOA has significant impacts on human health (Pope III and Dockery, 2006), air quality (Kanakidou et al, 2005;McFiggans et al, 2006), and global climate change (Hansen and Sato, 2001;Adams et al, 2001;Pokhrel et al, 2016).…”

Prospects for reconstructing paleoenvironmental conditions from organic compounds in polar snow and ice

“…The most widely used pre-concentration method is solid phase extraction (SPE) which is applied to non-polar anthropogenic compounds, like polycyclic aromatic hydrocarbons (PAHs), pesticides, polychlorinated biphenyls (PCBs) and perand polyfluoroalkyl substances (PFASs). For non-volatile compounds, another common preconcentration method is solvent evaporation, often using a rotary evaporator (Fu et al, 2016;Kawamura, 1993;Pokhrel et al, 2015;Pokhrel et al, 2016). For some compounds stir bar sorptive extraction has shown potential (Müller-Tautges et al, 2014), however SPE via cartridge and disc materials are currently more versatile due to the availability of a wider range of sorbents, which allows more targeted method optimisations.…”

“…Seki et al (2015) effectively concentrated fatty acids in LLE, followed by saponification with KOH in methanol and derivatisation with N,O-Bis(trimethylsilyl)fluoroacetamide (BSTFA) before analysis by GC-MS, showing recoveries of 75-82%. Pokhrel et al (2015) concentrated the samples with a rotavap (100 mL evaporated to dryness) with recoveries >70% and LODs of 1 ng/L with derivatisation with BF 3 /butanol followed by GC-MS. A similar method was used for analysing monoterpene and isoprene secondary organic aerosol (SOA) products showing analogous performances (Pokhrel et al, 2016). Pokhrel et al (2016) used a rotavap and 150 mL of melted ice after addition of KOH to convert organic acids into potassium salts making them less volatile, followed by derivatisation with BSFTA and analysis in GC-MS.…”