Earth, Ocean and Atmospheric Sciences, University of British Columbia (UBC), Vancouver, BC, Canada; BGC Engineering Inc., 500-980 Howe St., Vancouver, BC, Canada.
Geological Survey of Finland (GTK), Espoo, Finland.
J Contam Hydrol. 2018 Jul;214:65-74. doi: 10.1016/j.jconhyd.2018.05.007. Epub 2018 May 30.
Accurate predictions of solute release from waste-rock piles (WRPs) are paramount for decision making in mining-related environmental processes. Tracers provide information that can be used to estimate effective transport parameters and understand mechanisms controlling the hydraulic and geochemical behavior of WRPs. It is shown that internal tracers (i.e. initially present) together with external (i.e. applied) tracers provide complementary and quantitative information to identify transport mechanisms. The analysis focuses on two experimental WRPs, Piles 4 and Pile 5 at the Antamina Mine site (Peru), where both an internal chloride tracer and externally applied bromide tracer were monitored in discharge over three years. The results suggest that external tracers provide insight into transport associated with relatively fast flow regions that are activated during higher-rate recharge events. In contrast, internal tracers provide insight into mechanisms controlling solutes release from lower-permeability zones within the piles. Rate-limited diffusive processes, which can be mimicked by nonlocal mass-transfer models, affect both internal and external tracers. The sensitivity of the mass-transfer parameters to heterogeneity is higher for external tracers than for internal tracers, as indicated by the different mean residence times characterizing the flow paths associated with each tracer. The joint use of internal and external tracers provides a more comprehensive understanding of the transport mechanisms in WRPs. In particular, the tracer tests support the notion that a multi-porosity conceptualization of WRPs is more adequate for capturing key mechanisms than a dual-porosity conceptualization.
准确预测废石堆（WRP）中的溶质释放对于矿山相关环境过程的决策至关重要。示踪剂提供了可用于估计有效传输参数和理解控制 WRP 水力和地球化学行为机制的信息。研究表明，内部示踪剂（即初始存在）与外部示踪剂（即施加的）一起提供了互补和定量的信息，以识别传输机制。该分析集中在安塔米纳矿山（秘鲁）的 4 号堆和 5 号堆两个实验性 WRP 上，在三年的时间里，在排放中监测了内部氯化物示踪剂和外部施加的溴化物示踪剂。结果表明，外部示踪剂提供了与相对较快的流动区域有关的传输的见解，这些区域在更高的补给速率事件期间被激活。相比之下，内部示踪剂提供了对控制从堆内低渗透性区释放溶质的机制的见解。速率限制的扩散过程可以通过非局部质量转移模型来模拟，影响内部和外部示踪剂。质量转移参数对非均质性的敏感性对于外部示踪剂比对内部示踪剂更高，这反映了与每个示踪剂相关的流径的不同平均停留时间。内部和外部示踪剂的联合使用提供了对 WRP 中传输机制的更全面理解。特别是，示踪剂测试支持了这样一种观点，即 WRP 的多孔隙概念化比双孔隙概念化更适合捕捉关键机制。
