重庆市酉阳天坑沉积物记录的近百年来岩溶小流域土壤侵蚀历史
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西南大学地理科学学院

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重庆市科技局-院士专项(2022YSZX- JCX0008CSTB)、科技中央高校基本科研项目(SWU-KQ25023)和西南大学创新研究2035先导计划项目(SWU-XDZD22003)共同资助


A Century-long Soil Erosion History Documented in Tiankeng Sediments from a Small Karst Catchment Youyang County, Chongqing
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School of Geographical Sciences

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Supported by the Chongqing Science and Technology Bureau - Academician Program (No.2022YSZX-JCX0008CSTB), Fundamental Research Funds for the Central Universities (No.SWU-KQ25023) and Southwest University Innovation Research 2035 Pilot Program (No.SWU-XDZD22003)

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    摘要:

    岩溶区土壤侵蚀历史研究可为评估区域生态恢复潜力和区域水土保持工作提供参考。针对近50年土壤侵蚀研究已有大量成果,然而,重庆市岩溶区近百年土壤侵蚀演变机制尚不清楚。本研究以重庆市酉阳天坑为研究对象,应用137Cs、210Pb定年法确定剖面年代框架,计算小流域土壤侵蚀模数,结合区域史志资料、环境代用指标,对比前人研究资料,探讨近百年来重庆市岩溶区土壤侵蚀历史和机制。结果表明:研究区土壤侵蚀历史可分为三个阶段,1897—1955年,1955—1965年和1965—2023年;研究区小流域近百年沉积速率和平均侵蚀模数变化较大,1955—1965年期间的沉积速率和侵蚀模数分别为2.30 cm·a-1和1109 t·km-2·a-1,显著高于其他两阶段的沉积速率和侵蚀模数;与重庆市巫山常家洼洼地和重庆市中梁山洼地的土壤侵蚀历史研究对比发现,近百年来重庆市岩溶小流域的沉积速率与侵蚀模数变化基本一致,均经历了先升高后降低的过程,其侵蚀模数高值出现在20世纪50年代末;小流域侵蚀模数的高值阶段(1955—1965年)与极端干旱及20世纪50年代末的大面积伐木事件耦合,史志资料显示该事件导致森林面积显著减少,此外,沉积剖面的δ13Corg值与磁化率的突增,也指示着极端干旱和强烈的人类活动对环境的共同作用。该时期的极端干旱与大面积伐木事件是加剧重庆市岩溶区土壤侵蚀的重要原因。本研究为重庆岩溶区近百年流域土壤侵蚀过程研究提供了新的资料,对全面理解该地区近百年来石漠化演变历史和推进该地区水土保持工作有一定意义。

    Abstract:

    【Objective】Clarifying the historical trajectory of soil erosion in karst regions and investigating the mechanisms of soil and water loss are of great significance for evaluating the ecological restoration potential of regional reforestation and advancing soil and water conservation efforts. While substantial research achievements have been made in soil erosion studies over the past five decades, the evolutionary mechanisms of soil erosion in Chongqing""s karst areas over the past century remain unclear. 【Method】This study focused on a mature Tiankeng in Banxi Town, Youyang County, Chongqing Municipality, located in a typical karst region of Southwest China. The research employed the radioactive nuclide dating methods of ¹³⁷Cs and ²¹⁰Pb to establish a chronological sequence of the sediment profile within the Tiankeng. By integrating sedimentary environmental indicators with historical records of human activities, the soil erosion history over the past century in the Xiaojiazhai karst sub-catchment (where the Tiankeng resides) was reconstructed. In parallel, the findings were compared with research results from the Zhongliang Mountain karst depression and Changjiawa depression in Chongqing to investigate the impacts of human activities on soil erosion processes in the karst areas of Chongqing Municipality at a centennial scale. 【Result】The results indicated that the soil erosion history in the study area could be divided into three phases: 1897–1955, 1955–1965, and 1965–2023. Over the past century, the sedimentation rate and average erosion modulus in the sub-catchment exhibited significant variations. During 1955–1965, the sedimentation rate and erosion modulus reached 2.30 cm·a⁻¹ and 1109 t·km⁻²·a⁻¹, respectively, which were markedly higher than those of the other two phases. Comparative analysis with soil erosion histories from the Changjiawa Depression in Wushan County and the Zhongliang Mountain Depression in Chongqing revealed that sedimentation rates and erosion moduli in karst sub-catchments of Chongqing over the past century followed a consistent pattern of initial increase followed by decline, with peak erosion modulus values occurring in the late 1950s. To further assess the influence of precipitation on erosion modulus, a correlation analysis between precipitation data and erosion modulus in Youyang County was conducted. The results demonstrated no significant correlation (R² = 0.0059) between precipitation and erosion modulus over the past century, suggesting that precipitation variation likely did not dominate the pronounced changes in soil erosion within the Tiankeng area during this period. Also, the high erosion modulus phase (1955–1965) coincided with extreme drought events and large-scale deforestation in the late 1950s, coinciding with a drastic reduction in forest coverage during this period. Additionally, abrupt increases in δ¹³Corg values and magnetic susceptibility within the sediment profile provided further evidence of the combined impacts of extreme drought and intensive human activities on environmental degradation. These findings suggest that extreme drought and deforestation during this period were critical drivers of intensified soil erosion in Chongqing""s karst regions. 【Conclusion】The study highlights that regional environmental changes caused by intense human activities far exceeded those resulting from natural conditions and thus, provides novel insights into century-scale soil erosion processes in Chongqing’s karst catchments. The findings enhance understanding of regional desertification mechanisms and inform targeted strategies for soil-water conservation.

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刘 芳,蒋勇军,田 兴,戴 涛,韩 莎.重庆市酉阳天坑沉积物记录的近百年来岩溶小流域土壤侵蚀历史[J].土壤学报,DOI:10.11766/trxb202412220500,[待发表]
LIU Fang, JIANG Yongjun, TIAN Xing, DAI Tao, HAN Sha. A Century-long Soil Erosion History Documented in Tiankeng Sediments from a Small Karst Catchment Youyang County, Chongqing[J]. Acta Pedologica Sinica, DOI:10.11766/trxb202412220500,[In Press]

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  • 收稿日期:2024-12-22
  • 最后修改日期:2025-04-03
  • 录用日期:2025-05-10
  • 在线发布日期: 2025-05-13
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