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首页> 外文期刊>Geomorphology >Fingerprinting changes of source apportionments from mixed land uses in stream sediments before and after an exceptional rainstorm event
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Fingerprinting changes of source apportionments from mixed land uses in stream sediments before and after an exceptional rainstorm event

机译：在特殊暴雨事件发生前后，对河流沉积物中混合土地利用的源分配的指纹变化进行指纹分析

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摘要

The loss of fertile topsoil is one of the principal soil degradation problems in mountain agroecosystems worldwide. Soil erosion rates reach their maximum during exceptional storm events that remove soil particles, especially from unprotected topsoil. In Mediterranean mountainous environments, several centuries of non irrigated agriculture and the subsequent removal of natural vegetation for developing agriculture has increased the surface area prone to erosion. In addition, the irregularity in exceptional precipitation events results in a great loss of fertile soil, the subsequent siltation of reservoirs and a decrease in water quality. To analyse the soil response to exceptional events, 161 source samples were collected in a 23 km(2) catchment that was mostly cultivated at the beginning of the last century. Source samples were distributed over the five main land use/land covers such as agricultural land, pine afforestation, open forest, bare soil and channel bank areas. Furthermore, 20 channel bed sediment samples were collected along the main streams before and after the exceptional storm event to document changes in the sediments. In addition, floodplain sediments were collected to provide a close replication of sediments deposited during regular storm events. Source apportionments were calculated using the FingerPro unmixing model in the pre-event, regular events and post-event scenarios.The unmixing outputs displayed a large variation of source apportionments from the upper part to the lower part of the catchment and from pre- to post-event sediments. After the event, a decrease of 70% of the clay fraction and its associated elements such as Fe, Al, K, Ba, Sr, Rb, Pb, Zn, V,Cs-137, K-40, Th-232 and SOC along with a rise in contents of elements associated with the coarse fraction (Si, Nb, Zr, Ti, P and Ra-226) was recorded in the channel bed sediments. At the catchment outlet, the pre-event sediment showed substantial contributions from bare soil (29%) and from agriculture and channel banks, which both reached 35%, while the channel bank was the main source along the catchment ranging between 44 and 71%. The low contribution from soil under natural covers with a mean value 4% underlines the benefits of vegetation to prevent soil loss. In the post-event sediment, the channel bank contribution increased up to 63% at the catchment outlet. Our findings highlight the hazards of exceptional storm events on modifying sediment source contribution and exporting fine sediment. (C) 2019 Elsevier B.V. All rights reserved.
机译：肥沃的表层土壤流失是全世界山区农业生态系统中主要的土壤退化问题之一。在特殊的暴风雨事件中，土壤侵蚀率达到最大值，这会清除土壤颗粒，特别是不受保护的表层土壤中的颗粒。在地中海山区环境中，几个世纪的非灌溉农业以及随后为发展农业而去除的天然植被增加了容易遭受侵蚀的表面积。此外，异常降水事件的不规则性导致大量肥沃土壤流失，随后的水库淤积和水质下降。为了分析土壤对异常事件的响应，在一个23 km（2）的流域收集了161个源样品，这些流域大多数是在上世纪初开始种植的。来源样本分布在五个主要的土地利用/土地覆盖上，例如农业用地，松树造林，开阔的森林，裸露的土壤和河床岸地区。此外，在异常暴风雨发生前后，沿主要河流收集了20个河床沉积物样本，以记录沉积物的变化。此外，洪泛区的沉积物被收集起来，以提供常规暴风雨期间沉积物的紧密复制。在事件发生前，常规事件和事件后场景中使用FingerPro分解模型计算源分配，分解输出显示了从流域的上部到下部以及从流域的前到后的很大的源分配变化事件沉积物。事件发生后，粘土分数及其相关元素（如铁，铝，钾，钡，锶，R，铅，铅，锌，钒，铯-137，钾-40，Th-232和在河床沉积物中记录了SOC以及与粗颗粒（Si，Nb，Zr，Ti，P和Ra-226）相关的元素含量的增加。在集水口，事件前的沉积物显示了裸土（29％）以及农业和河岸的大量贡献，两者均达到35％，而河岸是流域的主要来源，占44％至71％ 。自然覆盖下土壤的平均贡献值低于4％，这表明植被对防止土壤流失的好处。在事后沉积物中，流域出口处的河岸贡献增加了63％。我们的研究结果突显了异常风暴事件对改变泥沙源贡献和输出细沙的危害。 （C）2019 Elsevier B.V.保留所有权利。

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  • 来源
    《Geomorphology》 |2019年第15期|216-229|共14页
  • 作者

    Lizaga Ivan; Gaspar Leticia; Blake William H.; Latorre Borja; Navas Ana;

  • 作者单位

    Spanish Natl Res Council EEAD CSIC, Dept Soil & Water, Estn Expt Aula Dei, Ave Montanana 1005, Zaragoza 50059, Spain;

    Spanish Natl Res Council EEAD CSIC, Dept Soil & Water, Estn Expt Aula Dei, Ave Montanana 1005, Zaragoza 50059, Spain;

    Univ Plymouth, Sch Geog Earth & Environm Sci, Plymouth, Devon, England;

    Spanish Natl Res Council EEAD CSIC, Dept Soil & Water, Estn Expt Aula Dei, Ave Montanana 1005, Zaragoza 50059, Spain;

    Spanish Natl Res Council EEAD CSIC, Dept Soil & Water, Estn Expt Aula Dei, Ave Montanana 1005, Zaragoza 50059, Spain;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Radionuclides; Geochemistry; FingerPro unmixing model; Virtual mixtures;

    机译：放射性核素;地球化学;FingerPro分解模型;虚拟混合物;

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