Links between sediment structures and ecological processes in the hyporheic zone: ground‐penetrating radar as a non‐invasive tool to detect subsurface biologically active zones
Links between sediment structures and ecological processes in the hyporheic zone: ground‐penetrating radar as a non‐invasive tool to detect subsurface biologically active zones
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DOI：
10.1002/eco.1530
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发表时间：
2015-06
期刊：
影响因子：
2.6
通讯作者：
F. Mermillod‐Blondin;T. Winiarski;A. Foulquier;Anne Perrissin;P. Marmonier
中科院分区：
文献类型：
--
作者：
F. Mermillod‐Blondin;T. Winiarski;A. Foulquier;Anne Perrissin;P. Marmonier
在地貌单元（浅滩、水池和砾石坝）的尺度上，潜流带对溪流和河流功能的贡献取决于地表水和地下水之间的水文交换。这些交换在很大程度上受沉积物结构和质地的控制，而这些结构和质地很难用传统方法（铲取和冷冻取芯）进行评估。我们的目的是评估一种非破坏性的方法，探地雷达（GPR）的能力，以检测与砾石床河流地下生物活性区相关的沉积物结构。经过地质雷达数据采集和处理后，砾石坝的三维重建可以识别两种沉积相：鹅卵石/砾石岩相表示为“粗”，砂/砾石岩相表示为“细”。我们沿沿着两个纵向剖面（每个剖面对应于通过GPR识别的岩相）安装了测压计，并监测了20天的水头和温度。水和沉积物取样沿着这两个配置文件，以测量水的物理化学，沉积物特性，细菌丰度和活动，和间隙无脊椎动物组合。这些测量结果证实，这两个剖面具有不同的水文流速和相关的生物活动。在粗剖面中的快速水输送为具有有机物的潜流带提供燃料，而在细剖面中的水和有机物供应较低。因此，较高的有机质供应的粗剖面与较高的微生物活动和无脊椎动物的密度和多样性。因此，探地雷达可以作为一种有效的工具来探测沉积物的功能发挥了关键作用的潜流带功能。版权所有© 2014约翰威利父子有限公司.
At the scale of geomorphological units (riffles, pools, and gravel bars), the contribution of the hyporheic zone to the functioning of streams and rivers depends on the hydrological exchanges between surface water and groundwater. These exchanges are largely controlled by sediment structure and texture, which are difficult to assess with classical methods (shovelling and freeze coring). We aimed to evaluate the ability of a non‐destructive method, ground‐penetrating radar (GPR), to detect sediment structures associated with subsurface biologically active zones in a gravel‐bed river. After GPR data acquisition and processing, a three‐dimensional reconstruction of a gravel bar permitted the identification of two sediment facies: a cobble/gravel lithofacies denoted as ‘coarse’ and a sand/gravel lithofacies denoted as ‘fine’. We installed piezometers along two longitudinal profiles (each corresponding to a lithofacies identified by GPR) and monitored hydraulic head and temperature for 20 days. Water and sediments were sampled along the two profiles to measure water physicochemistry, sediment characteristics, bacterial abundance and activity, and interstitial invertebrate assemblages. These measurements confirmed that the two profiles were characterized by distinct hydrological flow rates and associated biological activities. Rapid water transport in the coarse profile fuelled the hyporheic zone with organic matter, whereas water and organic matter supplies were lower in the fine profile. Consequently, the higher supply of organic matter in the coarse profile was associated with higher microbial activities and invertebrate density and diversity. Therefore, GPR could be an efficient tool to detect the sediment features playing a key role in hyporheic zone functioning. Copyright © 2014 John Wiley & Sons, Ltd.