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

Monoterpene and isoprene secondary organic aerosol (SOA) tracers are reported for the first time in an Alaskan ice core to better understand the biological source strength before and after the industrial revolution in the Northern Hemisphere. We found significantly high concentrations of monoterpene- and isoprene-SOA tracers (e.g., pinic, pinonic, and 2-methylglyceric acids, 2-methylthreitol and 2-methylerythritol) in the ice core, which show historical trends with good correlation to each other since 1660s. They show positive correlations with sugar compounds (e.g., mannitol, fructose, glucose, inositol and sucrose), and anti-correlations with alpha-dicarbonyls (glyoxal and methylglyoxal) and fatty acids (e.g., C-18:1) in the same ice core. These results suggest similar sources and transport pathways for monoterpene- and isoprene-SOA tracers. In addition, we found that concentrations of C-5-alkene triols (e.g., 3-methyl-2,3,4-trihydroxy-1-butene, cis-2-methyl 1,3,4-trihydroxy-1-butene and trans-2-methyl-1,3,4-trihydroxy-1-butene) in the ice core have increased after the Great Pacific Climate Shift (late 1970s). They show positive correlations with a-dicarbonyls and fatty acids (e.g., C-18:1) in the ice core, suggesting that enhanced oceanic emissions of biogenic organic compounds through the marine boundary layer are recorded in the ice core from Alaska. Photochemical oxidation process for these monoterpene- and isoprene-/sesquiterpene-SOA tracers are suggested to be linked with the periodicity of multi-decadal climate oscillations and retreat of sea ice in the Northern Hemisphere. (C) 2015 Elsevier Ltd. All rights reserved

南アラスカにおけるジカルボン酸、ω-オキソカルボン酸、ピルビン酸、α-ジカルボニルの1665年以降のアイスコア記録に関する研究 ： 北半球における気候変動とのリンク

Alaskan ice core (180 m long, 343 years) has been analyzed for a homologousseries of normal (C2 - C11), branched chain (iC4 - iC6), unsaturated (maleic, fumaric,methylmaleic and phthalic), multifunctional dicarboxylic (malic, oxomalonic and 4-oxopimelic), ω-oxocarboxylic acids (ωC2 - ωC9), pyruvic acid, glyoxal andmethylglyoxal using gas chromatography (GC/FID) and GC/mass spectrometry(GC/MS) to understand historical changes in water soluble organic aerosols.Similarly, homologous series of straight chain fatty acids (C12:0 - C30:0) has beendetected by using GC/FID and GC/MS system.Predominance of oxalic acid was found followed by adipic and succinic acid.Molecular distributions of ω-oxocarboxylic acids are characterized by thepredominance of 9-oxononanoic, followed by 4-oxobutanoic and glyoxylic acids.Historical concentrations of diacids, oxoacids and α-dicarbonyls are formed by theoxidation of precursor compounds emitted from biogenic and biomass burningactivities and which are controlled under climate oscillations and similarmeteorological parameters. Historical trends of monoterpene and isoprene SOAtracers showed significant concentrations since the 1660s, which are associated withambient atmospheric temperature and controlled by Aleutine Low.Molecular distributions of fatty acids are characterized by even carbon numberpredominance with a peak at palmitic (C16:0) followed by oleic (C18:1) and myristicacid (C14:0). The historical trends of short-chain fatty acids, together with correlationanalysis with inorganic ions and organic tracers suggest that short-chain fatty acids(except for C12:0 and C15:0) were mainly derived from sea surface micro layers. Incontrast, long-chain fatty acids (C20:0 - C30:0) are originated from terrestrial higherplants, soil organic matter and dusts, which are also linked with GreenlandTemperature Anomaly (GTA). Hence, this study suggests that Alaskan fatty acids arestrongly influenced by Pacific Decadal Oscillation/North Pacific Gyre Oscillationand/or extra tropical North Pacific surface climate and Arctic Oscillation.Organic tracers in ice core were derivatized with N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylsilyl chloride (TMCS) and pyridineand the derivatives were analyzed using GC/MS system. Levoglucosan,dehydroabietic and vanillic acid showed higher concentration with many sporadicpeaks since 1660s-1830s, 1913, and 2005. Moreover, there are a few discrepancies of higher spikes among them after 1980s with sporadic peaks in 1994-2007 fordehydroabietic acid. Historical trends of levoglucosan, dehydroabietic and vanillicacid showed that biomass burning activities from resin and lignin phenols from borealconifer trees and other higher plants and grasses were significant before 1840s andafter 1980s in the source regions of southern Alaska.Nitrite (NO2-), nitrate (NO3-), sulfate (SO42-) and methanesulfonate (CH3SO3-)were determined for an ice core of the Aurora Peak in southeast Alaska using ionchromatograph. They have common periods for higher spike during the years 1665-2008. They are attributed to the same source regions and similar pathways.Interestingly, we found multi-decadal scale atmospheric transport from lower tohigher latitudes in the North Pacific, which is reflected in historical concentrationtrends of anions. Moreover, correlation of levoglucosan with NH4+, NO3- , SO42- andNO2- suggests that these anions and cations are poor tracer of biomass burningactivities in the source regions of southern Alaska. Hence, this study revels a newdimension of anions periodic cycles in the North Paficic region, which may alter theconcept of other ice core studies in the Northern and Southern Hemisphere

Alpine snowpit profiles of polar organic compounds from Mt. Tateyama central Japan: Atmospheric transport of organic pollutants with Asian dust

Snowpit samples (n = 10) were collected (19 April 2008) from the snowpit sequences (depth 6.60 m) at the Murodo-Daira site (36.58 degrees N, 137.60 degrees E, elevation of 2450 m a.s.l.) of Mt. Tateyama (3015 m a.s.l.), central Japan. The first time, low molecular weight diacids, omega-oxoacids, pyruvic acid, and alpha-dicarbonyls were measured for this snowpit sequence. Higher concentrations of short-chain diacids (C-2-C-5) are observed in dusty snow than nondusty snow samples. Longer chain diacids (C-7-C-12) are significant in granular and dusty snow samples. Aromatic and aliphatic unsaturated diacids showed higher concentrations in the slightly dusty layer deposited in winter. Except for a clean layer, molecular distributions of diacids are characterized by the predominance of oxalic acid (C-2, ave, 20 +/- 22 ng/g-snow) followed by succinic (C-4, 7.2 +/- 5.9 ng/g-snow), and malonic acids (C-3, 3.3 +/- 2.9 ng/g-snow) for all the snow layers. Lower C-3/C-4 ratios (0.46) suggest that organic aerosols are rather fresh without serious photochemical aging during the long-range transport over central Japan. The higher concentrations of the secondary species in dusty snow than non-dusty samples were mainly attributed to the heterogeneous reaction. The strong correlations of incloud oxidation products of isoprene, aromatic acids, and fatty acids suggest that condensation, oxidation, and photolysis are important reaction mechanisms for the formation of diacids. Chinese Loess (Kosa particles) and Mongolian Gobi desert's dust provided the surface area for polar organic compounds, traveled to several thousand kilometers in the lower troposphere, and snow metamorphism altered the chemical composition of diacids and related compounds

Ice core profiles of saturated fatty acids (C-12:0-C-30:0) and oleic acid (C-18:1) from southern Alaska since 1734 AD: A link to climate change in the Northern Hemisphere

An ice core drilled at Aurora Peak in southeast Alaska was analyzed for homologous series of straight chain fatty acids (C-12:0-C-30:0) including unsaturated fatty acid (oleic acid) using gas chromatography (GC/FID) and GC/mass spectrometry (GC/MS). Molecular distributions of fatty acids are characterized by even carbon number predominance with a peak at palmitic acid (C-16:0, av. 20.3 +/- SD. 29.8 ng/g-ice) followed by oleic acid (C-18:1, 19.6 +/- 38.6 ng/g-ice) and myristic acid (C-14:0, 15.3 +/- 21.9 ng/g-ice). The historical trends of short-chain fatty acids, together with correlation analysis with inorganic ions and organic tracers suggest that short-chain fatty acids (except for C-12:0 and C-15:0) were mainly derived from sea surface micro layers through bubble bursting mechanism and transported over the glacier through the atmosphere. This atmospheric transport process is suggested to be linked with Kamchatka ice core SD record from Northeast Asia and Greenland Temperature Anomaly (GTA). In contrast, long-chain fatty acids (C-20.0-C-30:0) are originated from terrestrial higher plants, soil organic matter and dusts, which are also linked with GTA. Hence, this study suggests that Alaskan fatty acids are strongly influenced by Pacific Decadal Oscillation/North Pacific Gyre Oscillation and/or extra tropical North Pacific surface climate and Arctic oscillation. We also found that decadal scale variability of C-18:1/C-18:0 ratios in the Aurora Peak ice core correlate with the Kamchatka ice core SD, which reflects climate oscillations in the North Pacific. This study suggests that photochemical aging of organic aerosols could be controlled by climate periodicity. (C) 2014 Elsevier Ltd. All rights reserved

Dicarboxylic acids, oxocarboxylic acids and alpha-dicarbonyls in atmospheric aerosols from Mt. Fuji, Japan: Implication for primary emission versus secondary formation

Aerosol samples were collected at the summit of Mt. Fuji in July-August 2009 and analyzed for diacids and related compounds together with major ions to decipher the sources and formation process of organic aerosols in the free troposphere. Molecular distributions of diacids showed the predominance of oxalic acid (C-2) followed by succinic (C-4) and malonic (C-3) acids. The average concentration of total diacids is ten times higher in whole-day samples than night-only samples due to the uplift of planetary boundary layer in daytime, suggesting the day-time formation of diacids in the uplifted ground-level air mass along the mountain slope. A strong correlation is found between C-4 and levoglucosan in whole-day and nighttime samples. Liquid water content (LWC) shows strong correlations in nighttime with anthropogenic and biogenic secondary organic aerosol (SOA) tracers (e.g., adipic (0.90, p < 0.05) and phthalic acids (0.93, p < 0.05) and 3-methyl 2,3,4-trihydroxy-1-butene (0.95, p < 0.05), suggesting that aqueous-phase chemistry is important for the formation of water-soluble organic aerosols in the free troposphere. In whole-day samples, LWC is strongly correlated with organic carbon (r = 0.97, p < 0.05), and isoprene-SOA tracers such as methylthreitol (0.96, p < 0.05), methylerythritol (0.97, p < 0.05), 2-methylglyceric acid (0.94, p < 0.05) and glycolic acid (0.98, p < 0.05), suggesting that daytime SOAs are mainly from the oxidation of isoprene emitted from the regional forests on the foothill of Mt. Fuji. A strong correlation between LWC and glycolic acid further suggests that isoprene is the main precursor for the production of oxalic acid via glycolic acid as intermediate. This study supports the heterogeneous formation of diacids in the free troposphere