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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Fingerprinting upland sediment sources: particle size-specific magnetic linkages between soils, lake sediments and suspended sediments
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Fingerprinting upland sediment sources: particle size-specific magnetic linkages between soils, lake sediments and suspended sediments

机译：指纹识别高地沉积物来源：土壤，湖泊沉积物和悬浮沉积物之间特定于粒径的磁链

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Accelerated erosion of fine-grained sediment is an environmental problem of international dimensions. Erosion control strategies and targeting of mitigation measures require robust and quantitative identification of sediment sources. Here, we use magnetic 'fingerprinting' to characterize soils, and examine their affinity with and contribution to suspended sediments transported within two subcatchments feeding Bassenthwaite Lake, northwest England. A high-resolution soil magnetic susceptibility survey was made using a field susceptometer (ZH Instruments, SM400 probe). Combining the spatial and vertical (down-profile) soil magnetic data, a subset of soil profiles was selected for detailed, laboratory-based magnetic remanence analyses. The magnetic properties of the catchment soils are highly particle size-dependent. Magnetic analyses were performed on the 31-63 mu m fraction, for particle size-specific comparison both with the suspended sediments and lake sediments. Fuzzy cluster analysis groups the soil magnetic data into six clusters, apparently reflecting variations in parent material and horizon type, with three magnetically hard soils as unclassified outliers. Examination of the cluster affinity of the soils, Suspended sediments and lake sediments indicates that topsoils of the upper Newlands Valley and subsoils around Keskadale Beck are a major source of the Newlands Beck suspended load, and the recent (post-nineteenth century) sediments in the deep lake basin. Older lake sediments show strong affinity with a small number of the Derwent suspended sediments and one of the Glencleramackin soils. A large number of Derwent suspended sediments show no affinity with any of the soils or lake sediments, instead forming a coherent, discrete and statistically unclassified group, possibly resulting from mixing between the magnetically hard subsoils of the medium to high-altitude Glenderamackin and Troutbeck areas and softer, lower altitude Glencleramackin soils. The lack of any affinity of these suspended sediments with the lake sediments may indicate deposition along the Derwent flood plain and/or in the shallow delta of Lake Bassenthwaite. Particle size-specific magnetic fingerprinting is thus shown to be both highly discriminatory and quantitatively robust even within the homogeneous geological units of this catchment area. Such a methodological approach has important implications for small-large scale catchment management where sources of sediment arising from areas with uniform geology have been difficult to determine using other approaches, such as geochemical or radionuclide analyses.
机译：细颗粒沉积物的加速侵蚀是国际规模的环境问题。侵蚀控制策略和缓解措施的目标要求对沉积物来源进行有力且定量的识别。在这里，我们使用磁性“指纹”来表征土壤，并研究它们与在两个英格兰西北部的Bassenthwaite湖供养的子汇水区中输送的悬浮沉积物的亲和力和贡献。使用场磁化计（ZH仪器，SM400探针）进行了高分辨率的土壤磁化率调查。结合空间和垂直（向下剖面）土壤磁数据，选择了土壤剖面的一个子集，以进行详细的，基于实验室的剩磁分析。流域土壤的磁特性高度依赖于颗粒大小。对31-63微米级分进行了磁分析，以与悬浮沉积物和湖泊沉积物进行粒度特定的比较。模糊聚类分析将土壤磁数据分为六个聚类，显然反映了母体材料和层位类型的变化，其中三个硬磁土壤是未分类的异常值。对土壤，悬浮沉积物和湖泊沉积物的团簇亲和力的检查表明，纽兰兹河谷上部的表层土壤和凯斯卡代尔贝克周围的地下土壤是纽兰兹贝克悬浮负荷的主要来源，而最近（19世纪后）的沉积物是深湖盆地。较旧的湖泊沉积物与少数Derwent悬浮沉积物和Glencleramackin土壤之一表现出强烈的亲和力。大量Derwent悬浮沉积物与任何土壤或湖泊沉积物都没有亲和力，而是形成了一个连贯的，离散的和统计上未分类的类群，这可能是由于中度至高海拔的Glenderamackin和Troutbeck地区的磁性硬底土之间的混合所致较软的低海拔Glencleramackin土壤。这些悬浮沉积物与湖泊沉积物之间缺乏亲和力，可能表明沿德文特洪泛平原和/或浅水湖泊巴森斯维特湖沉积。因此，即使在该集水区的均质地质单位内，特定粒度的磁性指纹也具有很高的鉴别力和定量稳定性。这种方法学方法对小规模集水区管理具有重要意义，因为在小规模集水区管理中，很难使用其他方法（例如地球化学或放射性核素分析）来确定来自具有统一地质区域的沉积物来源。

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