Abstract
Abstract. A 180 m long (343 years) ice core was drilled in the saddle of Aurora Peak in Alaska (63.52∘ N, 146.54∘ W; elevation: 2825 m) and studied for biomass-burning tracers. Concentrations of levoglucosan and dehydroabietic and vanillic acids exhibit multidecadal variability, with higher spikes in 1678, 1692, 1695, 1716, 1750, 1764, 1756, 1834, 1898, 1913, 1966 and 2005 CE. Historical trends of these compounds showed enhanced biomass-burning activities in the deciduous broadleaf forests, boreal conifer forests, and/or tundra woodland and mountain ecosystems before the 1830s and after the Great Pacific Climate Shift (GPCS). The gradually elevated level of dehydroabietic acid after the GPCS is similar to p-hydroxybenzoic acid (p-HBA) from the Svalbard ice core, suggesting common climate variability in the Northern Hemisphere. The periodic cycle of levoglucosan, which seemed to be associated with the Pacific Decadal Oscillation (PDO), may be more involved with the long-range atmospheric transport than other species. These compounds showed significant correlations with global lower-tropospheric temperature anomalies (GLTTAs). The relations of the biomass-burning tracers with the PDO and GLTTA in this study suggest that their emission, frequency and deposition are controlled by the climate-driven forces. In addition, historical trends of dehydroabietic and vanillic acids (burning products of resin and lignin, respectively) from our ice core demonstrate the Northern Hemispheric connections to the common source regions as suggested from other ice core studies from Svalbard, Akademii Nauk and Tunu Greenland in the Northern Hemisphere.
Highlights
Biomass-burning tracers are ubiquitous in the atmosphere and deposited well on ice sheets as snow particles
We report levoglucosan, dehydroabietic acid and vanillic acid in an ice core collected from Aurora Peak in southern Alaska, an inland site facing the northeastern Pacific
Anhydrosugars such as levoglucosan are ubiquitous in the atmosphere; these are emitted significantly from biomassburning activities and deposited on the ice crystals and contribute to water-soluble organic carbon (WSOC; Zennaro et al, 2014; Verma et al, 2015; Gao et al, 2015; Legrand et al, 2016; Grieman et al, 2017, 2018a, b; Li et al, 2018; You et al, 2019)
Summary
Biomass-burning tracers (e.g., levoglucosan and dehydroabietic, vanillic, p-hydroxybenzoic and syringic acids) are ubiquitous in the atmosphere and deposited well on ice sheets as snow particles (i.e., precipitation; Pokhrel, 2015; MüllerTautges et al, 2016; Grieman et al, 2018a, b; Shi et al, 2019). Ammonium (NH+4 ), nitrite (NO−2 ), nitrate (NO−3 ) and sulfate (SO24−) were used to understand the atmospheric signals of biomass burning and/or the Pioneer Agriculture Revolution (PIA-GREV) in the Northern Hemisphere (Holdsworth et al, 1996; Legrand and Mayewski, 1997; Legrand et al, 2016). A signal of biomass burning is ammonium (e.g., [NH4]2SO4) in snow particles, which is a constituent of forest fire smoke (Holdsworth et al, 1996; Tsai et al, 2013). Pokhrel et al.: Ice core records of biomass-burning tracers in the North Pacific Rim
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