Hydroclimatic shifts in northeast Thailand during the last two millennia – the record of Lake Pa Kho
Hydroclimatic shifts in northeast Thailand during the last two millennia – the record of Lake Pa Kho
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DOI：
10.1016/j.quascirev.2015.01.007
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发表时间：
2015-03
影响因子：
4
通讯作者：
S. Chawchai;A. Chabangborn;S. Fritz;M. Väliranta;C. Mörth;M. Blaauw;P. Reimer;P. Krusic;L. Löwema
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文献类型：
--
作者：
S. Chawchai;A. Chabangborn;S. Fritz;M. Väliranta;C. Mörth;M. Blaauw;P. Reimer;P. Krusic;L. Löwema
东南亚大陆位于亚洲夏季风的中心路径，古气候资料仍然稀少。本文采用多指标（TOC、C/N、δ13C、生物硅和XRF元素数据）研究了泰国东北部Pa Kho湖1.5 m沉积物/泥炭层序，并得到了20个AMS14C年龄的支持。巴哥的水文气候重建表明，在公元前170 -公元370年、公元800-960年和公元1450年之后，夏季风增强；以及在公元370-800年和1300-1450年之间夏季季风的减弱。公元1700年以后，径流增加和养分供应增加可能与该地区的农业集约化和土地利用变化有关。这项研究填补了过去2000年东南亚夏季风变率数据覆盖的一个重要空白，并使热带辐合带（ITCZ）的平均位置能够根据与其他区域研究的比较推断出来。夏季季风降雨增强/减弱的间隔表明，在公元前170年至公元370年和公元800年至公元960年之间，ITCZ的平均位置位于北纬35°，而在公元370年至800年和公元1300年至1450年的干旱间隔期间，ITCZ的平均位置可能没有达到17°N以上。在公元1450年之后，降水变化的空间格局似乎发生了变化，当时推断的Pa Kho的水汽历史表明夏季ITCZ的平均位置更偏南。
The Southeast Asian mainland is located in the central path of the Asian summer monsoon, a region where paleoclimatic data are still sparse. Here we present a multi-proxy (TOC, C/N, δ13C, biogenic silica, and XRF elemental data) study of a 1.5 m sediment/peat sequence from Lake Pa Kho, northeast Thailand, which is supported by 20 AMS14C ages. Hydroclimatic reconstructions for Pa Kho suggest a strengthened summer monsoon between BC 170–AD 370, AD 800–960, and after AD 1450; and a weakening of the summer monsoon between AD 370–800, and AD 1300–1450. Increased run-off and a higher nutrient supply after AD 1700 can be linked to agricultural intensification and land-use changes in the region. This study fills an important gap in data coverage with respect to summer monsoon variability over Southeast Asia during the past 2000 years and enables the mean position of the Intertropical Convergence Zone (ITCZ) to be inferred based on comparisons with other regional studies. Intervals of strengthened/weaker summer monsoon rainfall suggest that the mean position of the ITCZ was located as far north as 35°N between BC 170–AD 370 and AD 800–960, whereas it likely did not reach above 17°N during the drought intervals of AD 370–800 and AD 1300–1450. The spatial pattern of rainfall variation seems to have changed after AD 1450, when the inferred moisture history for Pa Kho indicates a more southerly location of the mean position of the summer ITCZ.