Antarctic Ice Core Records of Saturated (C8–C30), Unsaturated (C16:1, Cis/Trans C18:1, and C18:2), and Branched-Chain (iC10–iC16) Fatty Acids and Dehydroabietic Acid from Preindustrial to Near-Present Time: Implications for Global Warming and Climate Changes

IF 2.9 3区 化学 Q2 CHEMISTRY, MULTIDISCIPLINARY
Ambarish Pokhrel*, Bhagawati Kunwar, Kimitaka Kawamura*, Mutsumi Nishikiori and Yoshiyuki Fujii, 
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引用次数: 0

Abstract

There is significant interest in identifying the impacts of climate changes on the Queen Maud Land-Mizuho Plateau of East Antarctica (69.05°S; 40.47°E, altitude: 1057 m mean above sea level). The atmospheric particles in polar regions can be deposited on snow and ultimately preserved on the ice sheet. Here, we explain the source and air-to-snow deposition process using the East Antarctica H-15 ice core records of lower molecular weight unsaturated (u-LFAs), saturated (s-LFAs; C8–C19), and higher molecular weight saturated (HFAs; C20–C30), and branched-chain (b-LFAs) fatty acids (FAs) (35 species) as regional paleoclimate signals. Molecular distributions of FAs in several ice layers are characterized by the predominance of α-linoleic (C18:2) or oleic (C18:1) acid, being different from the distribution of ice cores and snow pit samples from the Northern Hemisphere. We found historical increases in the concentrations of u-LFAs, s-LFAs, and b-LFAs in the ice core after 1850s, which are mainly derived by an enhanced sea-to-air emission from sea-surface microlayers due to the higher marine productivity during warmer periods. In contrast, HFAs of terrestrial higher plant origin also showed the recent concentration increases. However, the correlations of u-LFAs, s-LFAs, and HFAs with dehydroabietic acid (a tracer of wildfire burning of higher plant resins) are rather weak (R2 = 0.03, 0.02, and 0.19, respectively) in the ice core, suggesting different sources of FAs enhanced by meridional transport from the lower latitudes after the 1850s. The concentrations of these compounds are well correlated (p < 0.05) with the known climatic events, e.g., land and ocean temperature anomalies, sea ice extend (SIE), decreasing trend of stratospheric ozone, total solar irradiance, and Antarctic oscillation. Our findings suggest a regime shift in FA concentrations between the 1850s to 1990s, which could be associated with sea ice retreat in response to recent global warming that promotes more sea-to-air emission of u-LFAs.

Abstract Image

工业化前至近现代南极饱和(C8-C30)、不饱和(C16:1、顺式/反式C18:1和C18:2)和支链(iC10-iC16)脂肪酸和脱氢枞酸的冰芯记录:对全球变暖和气候变化的影响
气候变化对东南极洲莫德皇后高原-瑞穗高原(69.05°S;40.47°E,海拔:平均海拔1057米)。极地地区的大气颗粒可以沉积在雪上,并最终保存在冰盖上。本文利用南极东部H-15冰芯低分子量不饱和(u-LFAs)、饱和(s-LFAs;C8-C19)和更高分子量的饱和脂肪酸(hfa;C20-C30)和支链(b-LFAs)脂肪酸(FAs)(35种)作为区域古气候信号。不同于北半球冰芯和雪坑样品中FAs的分子分布,α-亚油酸(C18:2)或油酸(C18:1)在不同冰芯和雪坑样品中FAs的分子分布具有明显的优势。我们发现,19世纪50年代以后,冰芯中u-LFAs、s-LFAs和b-LFAs的浓度呈历史上升趋势,这主要是由于海洋生产力在温暖时期提高,海面微层向空气的排放增加。相比之下,陆生高等植物源的HFAs也呈现出近期浓度增加的趋势。然而,冰芯中u-LFAs、s-LFAs和hfa与脱氢枞酸(一种高级植物树脂野火燃烧的示踪剂)的相关性相当弱(R2分别为0.03、0.02和0.19),表明19世纪50年代以后,来自低纬度的经向输送增强了不同来源的FAs。这些化合物的浓度有很好的相关性(p <;0.05)与陆地和海洋温度异常、海冰扩展(SIE)、平流层臭氧减少趋势、太阳总辐照度和南极涛动等已知气候事件的关系。我们的研究结果表明,在19世纪50年代至90年代之间,FA浓度发生了变化,这可能与最近全球变暖导致海冰退缩有关,海冰退缩促进了更多的u- lfa向海洋排放到空气中。
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来源期刊
ACS Earth and Space Chemistry
ACS Earth and Space Chemistry Earth and Planetary Sciences-Geochemistry and Petrology
CiteScore
5.30
自引率
11.80%
发文量
249
期刊介绍: The scope of ACS Earth and Space Chemistry includes the application of analytical, experimental and theoretical chemistry to investigate research questions relevant to the Earth and Space. The journal encompasses the highly interdisciplinary nature of research in this area, while emphasizing chemistry and chemical research tools as the unifying theme. The journal publishes broadly in the domains of high- and low-temperature geochemistry, atmospheric chemistry, marine chemistry, planetary chemistry, astrochemistry, and analytical geochemistry. ACS Earth and Space Chemistry publishes Articles, Letters, Reviews, and Features to provide flexible formats to readily communicate all aspects of research in these fields.
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