Why does the solubility of alkaline earth metal carbonates and sulphates decrease down the group?

(N/A) The size of the anions (like $CO_3^{2-}$ and $SO_4^{2-}$) is much larger compared to the cations. Consequently,the lattice enthalpy remains almost constant as we move down the group. However,the hydration enthalpy of the cations decreases significantly down the group. Since the solubility depends on the balance between lattice enthalpy and hydration enthalpy,the decrease in hydration enthalpy leads to a decrease in solubility down the group.