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首页> 外文期刊>Estuarine Coastal and Shelf Science >Infaunal burrow ventilation and pore-water transport in muddy sediments
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Infaunal burrow ventilation and pore-water transport in muddy sediments

机译：泥质沉积物中的地下洞穴通风和孔隙水输送

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The ventilation of burrows by tube-dwelling benthos is understood to be important in determining rates of exchange of solutes between the sediment and overlying water. However, few models have attempted to link the burrow ventilation behavior of tube-dwelling organisms with their geochemical consequences. The classic cylinder model of bioirrigation in muddy sediments (Aller, R.C., 1980. Quantifying solute distributions in the bioturbated zone of marine sediments by defining an average microenvi-ronment. Geochimica et Cosmochimica Acta 44,1955-1965) links pore-water processes and burrow sizes and distributions in the sediment by assuming that burrows are fully flushed. The equivalence between the cylinder model and the more commonly used one-dimensional non-local exchange model depends upon this assumption. However, this assumption has seldom been tested in the field. We have extended the cylinder model of bioirrigation to include burrow ventilation activities of organisms. Burrow ventilation is modeled as a simple non-local exchange of burrow water with overlying water. Model simulations indicate that burrow ventilation has a large effect on vertical profiles and fluxes of solute tracers. We collected data on burrow geometry in the field by CT-scanning freshly collected sediment cores. At the same study sites, we measured activity profiles of ~(222)Rn, a naturally occurring radionuclide tracer of pore-water transport. With model geometry independently constrained, we tested the model by comparing our model-predicted profiles with measured profiles. Our results demonstrate that burrows in the field are not fully flushed. Our estimated burrow ventilation rates compare favorably with previous laboratory measurements. The inclusion of realistic burrow ventilation in this pore-water transport model strongly affects modeled solute profiles and fluxes. We demonstrate how model parameters can be determined from field samples and present a model that more realistically simulates pore-water transport processes in muddy sediments.
机译：人们认为，通过管式底栖生物对洞穴进行通风对于确定沉积物和上覆水之间的溶质交换速率非常重要。然而，很少有模型试图将管栖生物的洞穴通风行为与其地球化学后果联系起来。泥泞沉积物中生物灌溉的经典圆柱模型（Aller，RC，1980年。通过定义平均微环境来量化海洋沉积物生物扰动区中的溶质分布。Geochimicaet Cosmochimica Acta 44,1955-1965）将孔隙水过程与假设洞穴完全被冲洗，则洞穴的大小和在沉积物中的分布。圆柱模型与更常用的一维非局部交换模型之间的等价关系取决于此假设。但是，这种假设很少在现场进行测试。我们扩展了生物灌溉的气瓶模型，以包括生物的洞穴通风活动。洞穴通风的模型是将洞穴水与上层水进行简单的非本地交换。模型仿真表明，洞穴通风对溶质示踪剂的垂直剖面和通量有很大影响。我们通过CT扫描刚收集的沉积物岩心收集了田间洞穴几何形状的数据。在相同的研究地点，我们测量了〜（222）Rn的活动曲线，R（222）Rn是孔隙水传输的天然放射性核素示踪剂。在独立约束模型几何形状的情况下，我们通过将模型预测的轮廓与测量的轮廓进行比较来测试模型。我们的结果表明，田间的洞穴未被完全冲洗。我们估计的洞穴通风率与以前的实验室测量结果相比非常理想。在该孔隙水传输模型中包括实际的洞穴通风，极大地影响了建模的溶质剖面和通量。我们演示了如何从田间样品中确定模型参数，并提出了一个更现实地模拟泥质沉积物中孔隙水传输过程的模型。

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