Southern Baffin Island mean annual precipitation isotopes modulated by summer and autumn moisture source changes during the past 5800 years
Southern Baffin Island mean annual precipitation isotopes modulated by summer and autumn moisture source changes during the past 5800 years
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DOI：
10.1002/jqs.3390
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发表时间：
2021-11
影响因子：
2.3
通讯作者：
D. Gorbey;E. Thomas;S. Crump;K. Hollister;M. Raynolds;J. Raberg;Gregory Wet-Gregory- Wet-2139586212;J. Sepúlveda;G. Miller
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文献类型：
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作者：
D. Gorbey;E. Thomas;S. Crump;K. Hollister;M. Raynolds;J. Raberg;Gregory Wet-Gregory- Wet-2139586212;J. Sepúlveda;G. Miller
古水同位素记录可以阐明北极水循环对过去气候变化的反应。本文分析了加拿大努纳武特巴芬岛Qaupat湖植物源正链烷酸（蜡）的氢同位素组成（δ2H），以评估过去5.8 ka的水分来源和季节性。我们将此记录与来自同一湖泊的沉积古DNA（sedaDNA）推断的维管植物记录进行比较，旨在克服植物群落对叶蜡影响的不确定性。由于SedaDNA记录揭示了6.1ka时白桦定殖后的稳定植物群落，我们解释了植物蜡δ2H值可以反映气候，特别是年平均降水量δ2H。然而，正链烷酸同系物的分布表明，水生苔藓，这是不代表在sedaDNA记录，可能会变得更加丰富的走向现在。因此，我们不能排除植物群落的变化导致植物蜡δ2H记录变化的可能性，特别是长链蜡，通过这种记录变得不那么丰富。我们发现Qaupat湖中链植物蜡δ2H的富集与拉布拉多海夏季高表面温度相一致，这表明夏季和初秋的当地水分来源对该地区降水同位素的影响最大。
Paleo water isotope records can elucidate how the Arctic water cycle responded to past climate changes. We analyze the hydrogen isotope composition (δ2H) of plant‐derived n‐alkanoic acids (waxes) from Lake Qaupat, Baffin Island, Nunavut, Canada, to assess moisture sources and seasonality during the past 5.8 ka. We compare this record to a sedimentary ancient DNA (sedaDNA)‐inferred vascular plant record from the same lake, aiming to overcome the uncertainty of plant community impacts on leaf waxes. As the sedaDNA record reveals a stable plant community after the colonization of Betula sp. at 6.1 ka, we interpret plant wax δ2H values to reflect climate, specifically mean annual precipitation δ2H. However, the distributions of n‐alkanoic acid homologs suggest that aquatic mosses, which are not represented in the sedaDNA record, may become more abundant towards the present. Therefore, we cannot exclude the possibility that changes in the plant community cause changes in the plant wax δ2H record, particularly long‐chain waxes, which become less abundant through this record. We find that Lake Qaupat mid‐chain plant wax δ2H is enriched coincident with high Labrador Sea summer surface temperature, which suggests that local moisture sources in summer and early autumn have the greatest impact on precipitation isotopes in this region.