北山新场BS34钻孔岩样在不同温度下的水岩作用

Water-Rock Interaction of Granite From Borehole BS34 at Different Temperatures

高放废物深地质处置过程中,放射性核素衰变可能产生大量的热量,释放到处置硐室周围环境中将影响深部地质环境局部的水岩作用。为探究温度对新场场址深部地下水化学环境的影响,使用新场场址原状地下水与BS34钻孔深部花岗岩岩样,开展了不同温度下室内水岩作用研究。结果表明:BS34钻孔岩样与原状地下水反应后,水相的pH为6.4~8.5,总溶解固体(TDS)为1653.9~1759.6 mg/L。随着温度的升高,水溶液Na^(+)、K^(+)浓度增大,其中Na^(+)可能来源于钠长石溶解、阳离子交换作用,K^(+)可能来源于钾长石溶解;Ca^(2+)、Mg^(2+)、HCO_(3)^(-)浓度减少,主要以方解石和白云石的形式沉淀析出,反应温度越高,沉淀析出越多。

In the process of deep geological disposal of high-level radioactive waste,the decay of nuclide will generate a large amount of heat,which is released into the surrounding environment and affects the water-rock interaction of the deep geological environment.In order to explore the impact of temperature on the chemical environment of the deep groundwater in the Xinchang site,the undisturbed groundwater and deep granite samples at the Xinchang site were used to carry out water-rock interaction study at different temperatures.The research results show that the granite sample from borehole BS34 reacts with the undisturbed groundwater.The final pH value of the aqueous phase is between 6.4-8.5,and the TDS is between 1653.9-1759.6 mg/L.With the increase in temperature of the reaction system,the concentrations of Na^(+) and K^(+) in the aqueous phase increase,resulting from the dissolution of albite and cation exchange for Na^(+),and the dissolution of K-feldspar for K^(+),respectively.Meanwhile,the concentrations of Ca ^(2+),Mg ^(2+) and HCO_(3)^(-) decrease,mainly due to the precipitation of calcite and dolomite.The higher the reaction temperature,the more calcite and dolomite are precipitated.