Geologic carbon capture and sequestration (CCS) is a well-established method for storing large amounts of CO₂. However, monitoring the dissolved carbonate species associated with solubility trapping remains challenging. This study evaluated whether electrical resistivity (ER) can detect the carbonate-rich brines formed during solubility trapping, rather than focusing solely on freephase CO₂. Potassium carbonate (K₂CO₃), a highly conductive tracer, was examined within Austin Chalk limestone, cores saturated with solutions ranging from 0.1 to 5 wt% in deionized water (DI) and synthetic produced water (PW). Fluid-only tests showed minimal resistivity variation across a wide range of frequencies (12 Hz–10 kHz), but the resistivity decreased significantly with increasing carbonate concentration. In DI solutions, resistivity dropped from approximately 5.27Ω·m at 0.1 wt% to 0.16Ω·m at 5 wt%. When introduced into the Austin Chalk matrix (porosity ~25%–27%), the bulk resistivity increased owing to the resistive nature of the rock, but the inverse relationship between resistivity and carbonate concentration remained consistent. For example, in the K₂CO₂ + PW system at 1 kHz using the 4electrode setup, resistivity decreased from 1.81 Ω· m at 0.1 wt% to 1.50 Ω· m at 5 wt%. Frequency-dependent trends were also observed; higher frequencies (10 kHz) consistently yielded lower resistivities thanlow-frequency measurements (12 Hz), particularly in rock-saturated systems. Overall, these results establish a quantitative basis for applying electrical geophysical methods to monitor the changes in carbonate concentrations in carbonate reservoirs and support improved long-term CO₂ containment strategies.