Changing intensity of human activity over the last 2,000 years recorded by the magnetic characteristics of sediments from Xingyun Lake, Yunnan, China
Changing intensity of human activity over the last 2,000 years recorded by the magnetic characteristics of sediments from Xingyun Lake, Yunnan, China
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DOI：
10.1007/s10933-014-9806-2
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发表时间：
2015-12
影响因子：
2.1
通讯作者：
Duo Wu;Aifeng Zhou;Jianbao Liu;Xuemei Chen;Haitao Wei;Huiling Sun;Junqing Yu;J. Bloemendal
中科院分区：
文献类型：
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作者：
Duo Wu;Aifeng Zhou;Jianbao Liu;Xuemei Chen;Haitao Wei;Huiling Sun;Junqing Yu;J. Bloemendal
本文报道了云南行云湖2.46 m沉积物岩心的矿物磁性测量（磁化率、磁滞和等温剩余物、磁滞和热磁性质）。结果表明，湖泊沉积物中的磁性矿物以稳定的单域（SSD）铁磁性矿物为主，主要来源于入水流域土壤。在AD ~500 ~ 1050年间，磁化率急剧上升，磁性矿物粒度减小。这些变化伴随着Fe、Ti、Zr和Si浓度的增加和树花粉百分比的下降。华南地区岩洞的δ18O测量表明，这一时期的气候相对均匀。然而，文献证据表明，当时云南省的人口大量增加。我们的结论是，星云湖的晚全新世沉积物记录反映了人口增长导致的土壤侵蚀急剧增加，而人口增长反过来又导致了森林砍伐和农业活动的增加。星云湖的结果与研究点附近洱海的沉积物磁记录一致。因此，AD ~500 ~ 1050这段时间对应于云贵高原人类活动强度在区域尺度上的增加。
We report mineral magnetic measurements (magnetic susceptibility, anhysteretic and isothermal remanence, magnetic hysteresis and thermomagnetic properties) from a 2.46-m-long sediment core taken in Xingyun Lake, Yunnan, China. Results demonstrate that magnetic minerals in the lake sediment are dominated by stable single-domain (SSD) ferrimagnetic minerals derived mainly from in-washed catchment soil. Magnetic susceptibility increases sharply during the period AD ~500–1050, and the grain size of magnetic minerals decreases. These changes are accompanied by increases in the concentrations of Fe, Ti, Zr and Si, and by decreased tree pollen percentages. δ18O measures in speleothems from South China demonstrate that climate was relatively uniform during this interval. Documentary evidence, however, indicates a large increase in the human population of Yunnan Province at that time. We conclude that the late Holocene sediment record from Xingyun Lake reflects a dramatic increase in soil erosion that was caused by a growing human population, which in turn was responsible for increased deforestation and agricultural activity. Our results from Xingyun Lake are consistent with sediment magnetic records from Erhai Lake, located near our study site. We therefore conclude that the interval AD ~500–1050 corresponded to a regional-scale increase in the intensity of human activity on the Yunnan-Guizhou Plateau.