Data and supplementary information repository for quantifying stream-loss recovery in a spring using dual-tracer injections in the Snake Creek Drainage, Great Basin National Park, Nevada, USA

Simultaneous, short-pulse injections of two tracers (sodium bromide [Br-] and fluorescein dye) were made in a losing reach of Snake Creek in Great Basin National Park, Nevada, USA, to evaluate the quantity of stream-loss through permeable carbonates that resurfaces at a spring approximately 10 kilometers down drainage. A revised hydrogeologic cross section for a possible flow path of the infiltrated Snake Creek water is presented, and the results may inform water management in the region. First arrival and peak concentration of the two tracers occurred at 9.5 days and 12.7 days after injection, respectively. Fracture transport simulations indicate that Br- preferentially diffuses into immobile regions of the aquifer, and this diffusive flux is likely responsible for the major differences in the breakthrough curves. When considering the diffusive tracer flux, total apparent Br- and fluorescein dye recoveries were 16.9–22.1% and 21.7–24.3%, respectively. These findings imply that consideration of diffusive flux and long-term monitoring in fracture-dominated flow may support accurate quantification of tracer recovery. In addition, the apparent power law slopes of the breakthrough tails for both tracers were steeper at early times than have been attributed to heterogeneous advection or channeling in meter-scale tests, but the late-time Br- power law slope becomes less steep than has been attributed to diffusive exchange. These deviations may reflect fracture transport patterns that occur at larger scales.在美国内华达州大盆地国家公园的斯内克河（Snake Creek）消失河段，同步开展了两种示踪剂——溴化钠（sodium bromide，Br⁻）与荧光素染料（fluorescein dye）的短脉冲注射实验，以评估经可渗透碳酸盐岩渗漏后、在下游约10公里处泉眼复涌的河道渗漏量。本文给出了针对渗入斯内克河水的潜在径流路径的修正版水文地质剖面图，研究结果可为该区域的水资源管理提供决策参考。两种示踪剂的首次到达时间与峰值浓度分别出现在注射后的9.5天与12.7天。裂隙输运模拟（fracture transport simulations）结果显示，溴离子优先扩散至含水层（aquifer）的不动水区，该扩散通量或是造成两种示踪剂穿透曲线（breakthrough curves）出现显著差异的核心原因。在计入扩散示踪通量的前提下，溴离子与荧光素染料的表观总回收率分别为16.9%~22.1%与21.7%~24.3%。上述研究结果表明，在以裂隙为主导的径流系统中，兼顾扩散通量与长期监测，可实现示踪剂回收率的精准量化。此外，两种示踪剂穿透尾部的表观幂律（power law）斜率在早期阶段均高于米尺度试验中归因于非均质平流与管流（channeling）的斜率，但后期溴离子的幂律斜率则低于扩散交换（diffusive exchange）作用下的理论斜率。这些偏差或反映了大尺度下特有的裂隙输运模式。