Transport of thallium, germanium, and yttrium through fractured dolomite

Thallium (Tl), germanium (Ge), and yttrium (Y) are naturally occurring elements that have become contaminants of emerging concern due to their increasing use in industrial and technological applications. As a result of their widespread application, these elements can enter the environment, where they may migrate into aquifers, posing risks to groundwater quality and potentially impacting human and environmental health. This study investigates the transport dynamics of these elements through fractured dolomite rocks, considering the effects of pH, salinity, and rock chemical composition on transport mechanisms. Two types of fractured dolomite cores, Bonneterre dolomite, and Silurian dolomite, were used in column experiments to explore the transport of Tl, Ge, and Y under varying solution conditions. The experiments were conducted with different pH and salinity levels to assess their impact on element mobility. Although the transport behavior of these elements has received limited attention to date, the results presented here demonstrate that the rock matrix plays a critical role, alongside preferential flow in fractures, in influencing solute transport mechanisms. The study further highlights that the chemical composition of dolomite, as well as solution pH and salinity, significantly affect the mobility of these contaminants. For example, Ge, Tl and Y at pH 7 and 50 ppm salinity showed ∼100%, ∼100% and ∼ 20% total mean recovery, respectively, in Silurian dolomite, compared to ∼60%, <25% and 0% recovery, respectively, in Bonneterre dolomite. These factors are shown to strongly influence transport dynamics, suggesting that both the rock properties and solution conditions must be considered in understanding contaminant mobility.