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首页> 外文期刊>Aquatic Sciences >Quantification of phosphorus entrainment in a lowland river by in situ and laboratory resuspension experiments
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Quantification of phosphorus entrainment in a lowland river by in situ and laboratory resuspension experiments

机译：通过原位和实验室重悬实验定量测定低地河流中夹带的磷

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Hydrodynamics at the sediment water interface initiate and control the exchange of particles and associated phosphorus (P) between river sediment and the water column. Currently, no general analytical theory for cohesive sediment resuspension is available, so these properties must be inferred from direct measurements. In a moderately slow-flowing (annual mean velocity 0.1-0.3 ms~(-1)) stretch of the lowland River Spree, Germany, an in situ experiment (INS) and a laboratory experiment (LAB) with surface sediment (0-3 cm) were conducted concurrently in May 2005 using an erosion chamber. In both approaches, the entrainment of particles and partic-ulate P (PP) increased significantly as shear velocities were incrementally increased from 0.57 to 1.67 cm s~(-1). In repetitive INS runs, particle and PP entrainment rates at the lowest shear velocity applied differed by a factor of 5 and 11 (0.25-1.18 gm~(-2)h~(-1) and 4.1-45.9 mg m~(-2) h~(-1)), respectively, due to in situ river bed heterogeneities, specifically the presence or absence of a high-porosity fluff layer. These rates were on average 48 and 3 times higher, respectively, than those of LAB runs (0.01-0.02 gm~(-2)h~(-1) and 3.1-14 mg m~(-2) h~(-1), respectively), suggesting the temporary availability of local, in situ, fluffy surface layers on the river bed that are not preserved during sediment preparation for LAB runs. Such a transient storage feature has not been described previously in the literature for river sediments. The entrainment of this easily resuspendable and P rich material at a low flow-generated shear velocity can lead to batch-wise P burdens in the water column and consequently to a displacement of eutrophication potential. Those events would be underestimated in LAB experiments devoid of this fluffy layer.
机译：沉积物水界面处的流体动力学启动并控制了河流沉积物和水柱之间颗粒和相关磷（P）的交换。目前，尚无关于粘性沉积物再悬浮的通用分析理论，因此必须从直接测量中推断出这些性质。在德国低地施普雷河中度缓慢流动（年平均速度0.1-0.3 ms〜（-1））的河段中，进行了一个地表沉积物（0-3）的原位实验（INS）和实验室实验（LAB）于2005年5月同时使用侵蚀室进行。在两种方法中，随着剪切速度从0.57 cm s〜（-1）逐渐增加，颗粒和微粒P（PP）的夹带显着增加。在重复的INS运行中，在最低剪切速度下颗粒和PP的夹带率相差5倍和11倍（0.25-1.18 gm〜（-2）h〜（-1）和4.1-45.9 mg m〜（-2 ）h〜（-1）），分别是由于原位河床的非均质性，特别是高孔隙度绒毛层的存在或不存在。这些比率分别比LAB运行（0.01-0.02 gm〜（-2）h〜（-1）和3.1-14 mg m〜（-2）h〜（-1）高出48倍和3倍。 ）），这表明在LAB运行过程中沉积物准备期间未保留的河床局部，原地蓬松表面层的临时可用性。这种瞬态存储特征以前没有在文献中描述过河流沉积物。在流动产生的低剪切速度下夹带这种易于重悬和富P的物质会导致水柱中P的分批加料，从而导致富营养化潜力的位移。在没有该蓬松层的LAB实验中，这些事件将被低估。

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