In situ thermal recovery is utilized extensively for unconventional bitumen extraction in the Cold Lake-Beaver River (CLBR) basin in Alberta, Canada. Public health concerns have been raised over potable groundwater contamination and arsenic release adjacent to these operations within the CLBR basin, which have been linked to subsurface heating of aquifer sediments. Under localized heated conditions, As-bearing aquifer sediments have been shown to undergo water-rock interactions and release constituents at near neutral pH conditions; however, release mechanisms have yet to be conclusively reported. To investigate the hydrogeochemical processes of aquifer heating and solute transport in detail, this study applies a novel heated column design to mimic saturated aquifer materials in contact with a thermal recovery well while constraining flow and geochemical conditions. Two column experiment scenarios were considered using: 1) quartz [SiO₂] sand with 0.6 wt% pyrite [FeS₂]; and 2) aquifer sediments collected from the CLBR region. Heated temperature gradients between 50 °C and 90 °C were maintained within a 0.6 m section of the 3 m column with a flow rate of one pore volume per week. During heated low oxygen (<3 mg L⁻¹) conditions, results generally show increases in pH, Al, As, B, Mn, Mo, Si and Zn concentrations within and downgradient of the column heating section. Constituent release is primarily attributed to thermal desorption from Fe oxides, clay and silicate mineral dissolution, competitive anion exchange, and increased mixing. Overall results suggest that these mechanisms are responsible for increasing constituent concentrations in groundwater adjacent to in situ thermal recovery operations.

在 原位热回收被广泛用于加拿大艾伯塔省冷湖-比弗河（CLBR）盆地的非常规沥青提取。在CLBR盆地内与这些作业相邻的饮用水中污染物和砷释放已引起公众健康关注，这与地下含水层沉积物的加热有关。研究表明，在局部加热条件下，含砷含水层沉积物会发生水-岩相互作用，并在接近中性pH的条件下释放出各种成分。然而，释放机制尚未有定论报道。要详细研究含水层加热和溶质运移的水文地球化学过程，这项研究采用了新颖的加热柱设计，以模拟与热采井接触的饱和含水层材料，同时限制了流量和地球化学条件。考虑使用以下两种色谱柱实​​验方案：1）石英[SiO₂ ]砂，含0.6 wt％的黄铁矿[FeS ₂ ]；2）从CLBR地区收集的含水层沉积物。在3 m色谱柱的0.6 m区域内保持50°C和90°C之间的加热温度梯度，且每周的孔体积为一个流量。在加热的低氧（<3 mg L ^-1）条件下，结果通常显示柱加热段内的pH值，Al，As，B，Mn，Mo，Si和Zn浓度升高，且温度下降。成分释放主要归因于Fe氧化物的热脱附，粘土和硅酸盐矿物的溶解，竞争性阴离子交换和混合的增加。总体结果表明，这些机制是导致原位相邻地下水中组分浓度增加的原因。 热回收作业。