Millennial-scale diffusive migration of solutes in thick clay-rich aquitards: evidence from multiple environmental tracers
Millennial-scale diffusive migration of solutes in thick clay-rich aquitards: evidence from multiple environmental tracers
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DOI：
10.1007/s10040-010-0647-4
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发表时间：
2011-02-01
影响因子：
2.8
通讯作者：
Wassenaar, L. I.
中科院分区：
文献类型：
--
作者：
Hendry, M. Jim;Wassenaar, L. I.
高分辨率的一维配置文件的自然发生的环境示踪剂（H-3，三角洲D，三角洲O-18，C-14-DIC，C-14-DOC，Cl-36，He-4，和主要离子）和水力数据被用来研究在加拿大萨斯喀彻温省弱透水层系统的停留时间，运输机制，和孔隙水和溶质的来源。弱透水层系统包括80米的富含塑性粘土的Battleford，直到不协调地覆盖77米的晚白垩世塑性海相粘土。个别示踪剂独立地揭示了分子扩散的主要运输机制，在未氧化的nonfracture直到和粘土。输运模拟表明，在冰碛物沉积和冰退过程中，更新世晚期孔隙水（35-55 m）在距今1.5 - 3万年前（ka BP）侵位。晚全新世气候转型发生在7-12 ka BP。不同的示踪剂确定的事件的时间的差异归因于不准确的运输参数和边界条件的假设。这项研究表明，溶质运移在粘土丰富的弱透水层可以准确地预测超过20万年的时间尺度，并证明这种弱透水层是适合于长期隔离大多数废物。
High-resolution one-dimensional profiles of naturally occurring environmental tracers (H-3, delta D, delta O-18, C-14-DIC, C-14-DOC, Cl-36, He-4, and major ions) and hydraulic data were used to study residence times, transport mechanisms, and sources of pore water and solutes in an aquitard system in Saskatchewan, Canada. The aquitard system consisted of 80 m of plastic clay-rich Battleford till discomformably overlying 77 m of Late Cretaceous plastic marine clay. Individual tracers independently revealed molecular diffusion as the dominant transport mechanism in the unoxidized nonfractured till and clay. Transport modeling indicated that late Pleistocene-age pore water at 35-55 m below ground was emplaced 15-30 thousand years Before Present (ka BP) during till deposition and ice retreat. The late Holocene climatic transition was estimated to have occurred 7-12 ka BP. Differences in the timing of events determined with different tracers were attributed to inaccuracies in transport parameters and boundary condition assumptions. This study showed that solute transport in clay-rich aquitards can be accurately predicted for time scales beyond 20 ka, and proved such aquitards are suitable for long-term isolation of most wastes.