A 2000-year record of hydroclimate variability inferred from oxygen isotopes in lake sediments on Kangaroo Island (Karti/Karta), South Australia

IF 3.3 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Quaternary Science Reviews Pub Date : 2025-05-27 DOI:10.1016/j.quascirev.2025.109443

Mahfuzur Rahman , Lucinda Duxbury , Haidee Cadd , Robert Klaebe , Geraldine Jacobsen , John Tibby , Jonathan Tyler

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引用次数: 0

Abstract

Understanding past hydroclimate variability through high-resolution records is key to assessing the recurrence of extreme climatic events, including prolonged droughts and floods and for sustainable environmental and economic planning. This study presents a sub-decadal-scale hydroclimate reconstruction based on oxygen isotope analysis of ostracod valves, extracted from the sediments of Lashmars Lagoon, Kangaroo Island, South Australia. Sediment dating was based on 19 accelerator mass spectrometry (AMS) radiocarbon (¹⁴C) dates from pollen and plant macrofossils, alongside lead-210 and plutonium concentration analyses. Spanning the last ∼2000 years, the oxygen isotopes record a series of multi-decadal wet and dry periods, manifest in the relative precipitation-evaporation balance of the lake. Of note, the record implies periods of prolonged declines in water balance, tentatively interpreted as droughts, from ∼525 to 575 CE, ∼770–790 CE, ∼825–850 CE, and ∼980–1020 CE. By contrast, the periods from ∼150 to 450 CE and ∼600–750 CE were relatively wet. Unfortunately, ostracods were absent within the sediments deposited between ∼1250 and 1590 CE and as a result, no hydroclimatic pattern could be determined for this time period. The period from ∼1590 to 1800 CE appears to have been notably dry, prior to an increase in effective moisture during the last 200 years. The Lashmars Lagoon record exhibits similar trends to a record from Blue Lake, Mt. Gambier, approx. 500 km to the southeast. However, these records contrast with other hydroclimate records from further east, implying a complex relationship with regional climate drivers. Comparison with instrumental period rainfall data, and reconstructed indices for major ocean–atmosphere interactions suggests that periods of increased moisture balance on Kangaroo Island were influenced by a combination of Southern Ocean and Indian Ocean derived climate drivers.

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从南澳大利亚袋鼠岛（Karti/Karta）湖泊沉积物的氧同位素推断的2000年水文气候变化记录

通过高分辨率记录了解过去的水文气候变化是评估极端气候事件（包括长期干旱和洪水）重现的关键，也是可持续环境和经济规划的关键。本文基于对南澳大利亚袋鼠岛Lashmars泻湖沉积物介形类阀的氧同位素分析，进行了次年代尺度的水文气候重建。沉积物测年是基于19个加速器质谱（AMS）放射性碳（14C）的花粉和植物大化石测年，以及铅-210和钚浓度分析。在过去~ 2000年间，氧同位素记录了一系列多年代际的干湿期，体现在湖泊的相对降水-蒸发平衡中。值得注意的是，该记录表明，在~ 525 ~ 575 CE、~ 770 ~ 790 CE、~ 825 ~ 850 CE和~ 980 ~ 1020 CE期间，水平衡长期下降，初步解释为干旱。相比之下，从~ 150 ~ 450 CE和~ 600 ~ 750 CE的时期相对潮湿。不幸的是，在约1250至1590年间沉积的沉积物中没有介形类，因此无法确定这一时期的水文气候模式。从公元1590年到1800年，在过去200年有效水分增加之前，这一时期似乎非常干燥。拉什玛斯湖的记录与甘比尔山的蓝湖的记录显示出类似的趋势。东南方向五百公里。然而，这些记录与来自更东部的其他水文气候记录形成对比，暗示了与区域气候驱动因素的复杂关系。与仪器周期降水资料的比较和主要海洋-大气相互作用的重建指数表明，袋鼠岛水分平衡增加的周期受到南大洋和印度洋气候驱动因素的共同影响。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Quaternary Science Reviews 地学-地球科学综合

CiteScore

7.50

自引率

15.00%

发文量

388

审稿时长

3 months

期刊介绍： Quaternary Science Reviews caters for all aspects of Quaternary science, and includes, for example, geology, geomorphology, geography, archaeology, soil science, palaeobotany, palaeontology, palaeoclimatology and the full range of applicable dating methods. The dividing line between what constitutes the review paper and one which contains new original data is not easy to establish, so QSR also publishes papers with new data especially if these perform a review function. All the Quaternary sciences are changing rapidly and subject to re-evaluation as the pace of discovery quickens; thus the diverse but comprehensive role of Quaternary Science Reviews keeps readers abreast of the wider issues relating to new developments in the field.