Quantitative reconstruction of summer precipitation using a mid-Holocene δ 13 C common millet record from Guanzhong Basin, northern China
Quantitative reconstruction of summer precipitation using a mid-Holocene δ 13 C common millet record from Guanzhong Basin, northern China
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DOI：
10.5194/cp-12-2229-2016
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发表时间：
2016-12
影响因子：
4.3
通讯作者：
Qingjiang Yang;Xiaoqiang Li;Xinying Zhou;Keliang Zhao;N. Sun
中科院分区：
文献类型：
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作者：
Qingjiang Yang;Xiaoqiang Li;Xinying Zhou;Keliang Zhao;N. Sun
抽象的。为了定量重建特定地理区域的全新世降水，需要合适的代理和可靠的定年控制。在中国北方的沉积地层中发现了谷子（Panicum miliaceum）的种子，这些种子适合于进行全新世降水定量重建：它们的同位素碳组成（δ 13 C）给出了夏季生长季节（这里是6月中旬至9月）所需降水的量度，并允许这些种子被定年。因此，我们使用回归函数，作为系统研究谷子δ 13 C的一部分，对关中盆地（107°40′-107 ° 49 ′ E，33°39′-34 ° 45 ′ N）中全新世夏季降水进行了定量重建。结果表明，7.7- 3.4kaBP期间，中国夏季平均降水量为353 mm，比现今增加了17%，降水量的变率增大，尤其是5.2kaBP以后。6.1-5.5 ka BP期间夏季平均降水量最大值为414 mm，比今天高出109 mm（或36%），表明东亚夏季风（EASM）在此时达到峰值。这一工作为进一步研究古降水序列和夏季降水的变化提供了新的代用指标，将促进早期人类活动与环境变化关系的深入研究。
Abstract. To quantitatively reconstruct Holocene precipitation for particular geographical areas, suitable proxies and faithful dating controls are required. The fossilized seeds of common millet (Panicum miliaceum) are found throughout the sedimentary strata of northern China and are suited to the production of quantitative Holocene precipitation reconstructions: their isotopic carbon composition (δ13C) gives a measure of the precipitation required during the growing season of summer (here the interval from mid-June to September) and allows these seeds to be dated. We therefore used a regression function, as part of a systematic study of the δ13C of common millet, to produce a quantitative reconstruction of mid-Holocene summer precipitation in the Guanzhong Basin (107°40′–107°49′ E, 33°39′–34°45′ N). Our results showed that mean summer precipitation at 7.7–3.4 ka BP was 353 mm, ∼ 50 mm or 17 % higher than present levels, and the variability increased, especially after 5.2 ka BP. Maximum mean summer precipitation peaked at 414 mm during the period 6.1–5.5 ka BP, ∼ 109 mm (or 36 %) higher than today, indicating that the East Asian summer monsoon (EASM) peaked at this time. This work can provide a new proxy for further research into continuous paleoprecipitation sequences and the variability of summer precipitation, which will promote the further research into the relation between early human activity and environmental change.