| 摘要: |
| 流域土壤侵蚀是流域水文—气候—生态的集中表现之一，对生态、环境等有着重大影响，重建过去流域土壤侵蚀强度对理解区域人类活动具有重要意义。本文选取黄土高原西南部高山湖泊——六盘山天池沉积岩芯为研究对象，基于XRF岩芯元素数据分析，结合可靠的AMS 14C年代序列，重建了中晚全新世以来六盘山流域土壤侵蚀强度变化记录。结果显示：5570—1600 cal BP，流域土壤侵蚀整体较强，侵蚀强度逐渐减弱，其主要受控于降水变化，也受植被覆盖等因素的影响；随着晚全新世气候逐渐变干，1600 cal BP之后的侵蚀强度整体弱于前一时期，此时段由于人类活动的显著影响，加剧了流域的土壤侵蚀。太阳辐射可能是研究区土壤侵蚀强度变化的初始驱动力，ENSO通过驱动亚洲季风变化影响区域降水，进而直接影响流域土壤侵蚀的强度变化。 |
| 关键词: 六盘山 岩芯XRF扫描 土壤侵蚀 全新世 |
| DOI：10.7515/JEE202018 |
| CSTR： |
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| 基金项目:国家自然科学基金项目（41771208，41790421） |
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| Mid-late Holocene Soil Erosion Record from Lake Deposit of Liupan Mountains |
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ZHANG Huan, NIU Lili, YUAN Zijie, ZHANG Can, SUN Huiling, ZHANG Xinjia, ZHOU Aifeng
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1. Key Laboratory of Western China’s Environmental Systems (Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China
2. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Science, Nanjing 210008, China
3. Key Laboratory of Plateau Lake Ecology and Global Change, College of Tourism and Geography, Yunnan Normal University, Kunming 650500, China
4. The School of the Geo-Science & Technology, Zhengzhou University, Zhengzhou 450001, China
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| Abstract: |
| Background, aim, and scope Reconstruction of soil erosion is an efficient approach to understand regional ecology, environment and human activities. There are many studies on vegetation and climate change in Liupan Mountains, which located in the southwest of the Loess Plateau, however, the long-term evolution study on regional soil erosion remain poorly understood. Based on the analysis of XRF core element data of Tianchi sedimentary core and the reliable AMS 14C chronological sequence, this paper reconstructed the continuous record of soil erosion intensity of Liupan Mountains through mid to the late Holocene. Materials and methods The cores GSA07 and GSB07 were obtained from the center of Tianchi Lake, Liupan Mountains. The GSB07 (10.05 m) core was used as the research material to carry out XRF core scanning. Factor analysis of element data was obtained by SPSS 16.0. In addition, based on AMS 14C age of the parallel GSA07 core, the age of the GSB07 core was obtained by the way of mark layer docking. Results The bottom age of GSB07 is 5570 cal BP Through factor analysis of Al, Si, K, Ti, S, Cl, Ca, Fe, Mn, Rb, Sr, Zr, three principal component factors were extracted. The cumulative variance accounted for 77.64% of the total variance. FA 1 accounted for 53.15% of the total variance, which was the main contribution factor of sedimentary elements composition, of which Al, Si, K, Ti, Rb, Sr, Zr were the main load factors. Discussion After analyzing, we found that FA 1 can reflect the input of exogenous debris and indicate the strength of soil erosion in Liupan Mountains. In this paper, FA 1 was compared with the reconstructed precipitation and vegetation results in Liupan Mountains and nearby area. It was demonstrated that soil erosion in Liupan Mountains was mainly controlled by precipitation and affected by vegetation coverage and human activities. Meaning increased precipitation leads to the increase of soil erosion; the decrease of vegetation cover aggravates soil erosion; after 1600 cal BP, human activities also aggravated soil erosion by changing vegetation types. The power spectrum analysis of FA 1 and total solar irradiation (TSI) shows that TSI may have indirectly affected the soil erosion of this drainage area by influencing regional climate change. ENSO may have affected the precipitation of the area by driving the variation of Asian monsoon, and then affect the strength of soil erosion of Liupan Mountains. Conclusions During the period of 5570—1600 cal BP, the soil erosion is generally strong and the erosion intensity is gradually weakened which is mainly controlled by the change of rainfall, and also affected by the factors like vegetation coverage. With the climate drying in the late Holocene, the erosion intensity after 1600 cal BP was weaker than that during the previous period, and the soil erosion in this region was intensified due to the significant impact of human activities. The solar radiation may be the initial driving force of soil erosion intensity in the area. ENSO affects the regional precipitation by driving the change of Asian monsoon, and then directly affects the intensity of soil erosion intensity in the area. Recommendations and perspectives The climate change, vegetation type, human activities and other factors should all be considered when discussing the influencing factors of regional soil erosion. Vegetation restoration and reasonable human activities play an important role in soil and water conservation in the Loess Plateau. |
| Key words: Liupan Mountains XRF core scanning soil erosion the Holocene |
