A complete series of calcite-rhodochrosite solid solutions [(Ca1-xMnx)CO3] are prepared, and their dissolution processes in various water samples are experimentally investigated. The crystal morphologies of the solid solutions vary from blocky spherical crystal aggregates to smaller spheres with an increasing incorporation of Mn in the solids. Regarding dissolution in N2-degassed water, air-saturated water and CO2-saturated water at 25 °C, the aqueous Ca and Mn concentrations reach their highest values after 1240–2400 h, 6–12 h and < 1 h, respectively, and then decrease gradually to a steady state; additionally, the ion activity products (log_IAP) at the final steady state (≈ solubility products in log_Ksp) are estimated to be − 8.46 ± 0.06, − 8.44 ± 0.10 and − 8.59 ± 0.10 for calcite [CaCO3], respectively, and − 10.25 ± 0.08, − 10.26 ± 0.10 and − 10.28 ± 0.03, for rhodochrosite [MnCO3], respectively. As XMn increases, the log_IAP values decrease from − 8.44 ~ − 8.59 for calcite to − 10.25 ~ − 10.28 for rhodochrosite. The aqueous Mn concentrations increase with an increasing Mn/(Ca + Mn) molar ratio (XMn) of the (Ca1-xMnx)CO3 solid solutions, while the aqueous Ca concentrations show the highest values at XMn = 0.53–0.63. In the constructed Lippmann diagram of subregular (Ca1-xMnx)CO3 solid solutions, the solids dissolve incongruently, and the data points of the aqueous solutions move progressively up to the Lippmann solutus curve and then along the solutus curve or saturation curve of pure MnCO3 to the Mn-poor side. The microcrystalline cores of the spherical crystal aggregates are preferentially dissolved to form core hollows while simultaneously precipitating Mn-rich hexagonal prisms.

A complete series of the calcite–otavite solid solutions [(Ca1−xCdx)CO3] were prepared, and their dissolution processes lasting nine months were experimentally investigated. For the dissolution in the N2-degassed water, the Ca concentrations of the aqueous phases increased up to the steady states after 5040 h of dissolution, and the Cd concentrations of the aqueous phases increased up to the highest values and then decreased gradually to the steady states of 0.017–6.476 μmol/L after 5040 h of dissolution. For the dissolution in the CO2-saturated water, the Ca and Cd concentrations of the aqueous phases increased up to the peak values and then decreased gradually to the steady states of 0.94–0.46 mmol/L and 0.046–9.643 μmol/L after 5040 h of dissolution, respectively. For the dissolution in the N2-degassed water at 25 °C, the mean solubility products (log Ksp) and the Gibbs free energies of formation (ΔGfθ) were estimated to be −8.45–−8.42 and −1129.65–−1129.48 kJ/mol for calcite [CaCO3] and −11.62–−11.79 and −671.81–−672.78 kJ/mol for otavite [CdCO3], respectively. Generally, the log Ksp values decreased non-linearly, and the ΔGfθ values increased linearly with the increasing Cd/(Ca+Cd) mole ratio (XCd) of the (Ca1−xCdx)CO3 solid solutions. In the Lippmann diagrams constructed for the sub-regular (Ca1−xCdx)CO3 solid solutions with the estimated Guggenheim coefficients a0 = −0.84 and a1 = −3.80 for the dissolution in the N2-degassed water or a0 = −1.12 and a1 = −3.83 for the dissolution in the CO2-saturated water, the (Ca1−xCdx)CO3 solid solutions dissolved incongruently, moved progressively up to the quasi-equilibrium curves for otavite and then along the quasi-equilibrium curve from right to left, approached the solutus curve and finally reached the minimum stoichiometric saturation curve for calcite. The considerably Cd-poor aqueous phases were finally in equilibrium with the CdCO3-rich solid phases.

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The non-ideal solid solutions between calcite and smithsonite, [(Ca1–x Zn x )­CO3], were synthesized, and their interaction with different aqueous solutions at 25 °C was experimentally investigated. The X-ray diffraction spectra indicated that all synthesized minerals exhibited the calcite structure exclusively. After 180–240 days of dissolution in N2-degassed water (NDW) and air-saturated water (ASW), the aqueous Zn concentrations reached a constant value ranging from 0.002565 to 0.006133 and 0.002710 to 0.006374 mmol/L for the solid solutions with low Zn/(Zn + Ca) mole ratios (XZn < 0.075) or from 0.005416 to 0.076400 and 0.005128 to 0.067222 mmol/L for the solid solutions with high XZn (>0.864), respectively. After 180–240 days of dissolution in CO2-saturated water (CSW), the aqueous Zn concentrations reached a constant value ranging from 0.005938 to 0.081753 mmol/L for all solid solutions. The aqueous Zn/(Ca + Zn) mole ratios were considerably lower than the solid XZn. The aqueous Zn and Ca concentrations generally increased with increasing XZn for solid solutions with XZn < 0.075, while they decreased with increasing XZn for solid solutions with XZn > 0.864. The average solubility products (K sp) (≈ ion activity products at the constant state) were determined to be 10–8.36±0.10, 10–8.33±0.03, and 10–8.28±0.06 for calcite [CaCO3] in NDW, ASW, and CSW, respectively. Similarly, the average solubility products were determined to be 10–10.65±0.12, 10–10.60±0.08, and 10–10.47±0.06 for smithsonite [ZnCO3] in NDW, ASW, and CSW, respectively. The logarithm of K sp showed a slight increase with increasing XZn for solid solutions with XZn < 0.075, whereas it decreased with increasing XZn for the solids with XZn > 0.864. In the Lippmann diagram constructed with the Guggenheim coefficients a 0 = 2.72 and a 1 = −0.266 for the [(Ca1–x Zn x )­CO3] solid solutions, it was observed that the solid solutions dissolved non-stoichiometrically and moved progressively up to the minimum stoichiometric saturation curve for pure smithsonite and the solutus curve and then along them from right to left, finally reaching the saturation curve for calcite. The coexistence of Zn-poor aqueous solutions with ZnCO3-rich solids highlights the findings of the [(Ca1–x Zn x )­CO3] mineral–water reaction and its significance in the zinc geochemical cycle in Earth’s surface environments, contributing to a comprehensive understanding of these processes.