A quantitative study on accumulation of age mass around stagnation points in nested flow systems
A quantitative study on accumulation of age mass around stagnation points in nested flow systems
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DOI：
10.1029/2012wr012509
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发表时间：
2012-12
影响因子：
5.4
通讯作者：
Xiaowei Jiang;L. Wan;S. Ge;G. Cao;G. Hou;F. Hu;Xu-sheng Wang;Hailong Li;S. Liang
中科院分区：
文献类型：
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作者：
Xiaowei Jiang;L. Wan;S. Ge;G. Cao;G. Hou;F. Hu;Xu-sheng Wang;Hailong Li;S. Liang
嵌套流系统中的停滞区被认为对所运移物质（如流域中的金属离子和碳氢化合物）的聚集至关重要。然而，很少有定量研究来证明这一假设。在本文中，以年龄质量的运移为例，证明所运移物质可在停滞点周围聚集。分析了一系列不同深度流域中模型年龄的空间分布。我们发现，地下水年龄在每个停滞点周围都有局部或区域最大值，这证明了年龄质量的聚集。在局部、中间和区域流系统都发育良好的流域中，区域最大地下水年龄出现在流域谷底下方的区域停滞点处。这可归因于区域流系统的长运移距离以及水的停滞性。然而，当局部流系统占主导时，由于停滞作用，流域内的最大地下水年龄可能位于远离流域谷底的局部停滞点周围。通过一个案例研究来说明中国西北鄂尔多斯高原的地下水流和年龄情况。通过两个钻孔中由¹⁴C定年确定的示踪年龄以及不同弥散度下局部停滞点附近的模拟年龄，证实了停滞点周围年龄质量的聚集。这些结果将有助于阐明地下水流与流域内地下水年龄、水化学、矿产资源和碳氢化合物分布之间的关系。
The stagnant zones in nested flow systems have been assumed to be critical to accumulation of transported matter, such as metallic ions and hydrocarbons in drainage basins. However, little quantitative research has been devoted to prove this assumption. In this paper, the transport of age mass is used as an example to demonstrate that transported matter could accumulate around stagnation points. The spatial distribution of model age is analyzed in a series of drainage basins of different depths. We found that groundwater age has a local or regional maximum value around each stagnation point, which proves the accumulation of age mass. In basins where local, intermediate and regional flow systems are all well developed, the regional maximum groundwater age occurs at the regional stagnation point below the basin valley. This can be attributed to the long travel distances of regional flow systems as well as stagnancy of the water. However, when local flow systems dominate, the maximum groundwater age in the basin can be located around the local stagnation points due to stagnancy, which are far away from the basin valley. A case study is presented to illustrate groundwater flow and age in the Ordos Plateau, northwestern China. The accumulation of age mass around stagnation points is confirmed by tracer age determined by 14C dating in two boreholes and simulated age near local stagnation points under different dispersivities. The results will help shed light on the relationship between groundwater flow and distributions of groundwater age, hydrochemistry, mineral resources, and hydrocarbons in drainage basins.