How does acid deposition remove calcium and magnesium from soil?

Acid deposition removes essential nutrients like calcium and magnesium from soil through a process of chemical displacement and leaching. These nutrients, known as base cations, are typically held on the surfaces of soil particles at negatively charged sites.12

When acid deposition introduces high concentrations of hydrogen ions ($H^{+}$) into the soil, these ions displace the calcium ($C{a}^{2+}$) and magnesium ($M{g}^{2+}$) ions from their binding sites. Because these displaced nutrients do not adsorb strongly to soil particles, they become mobile and are easily leached downward by percolating water, effectively removing them from the upper soil profile where they are needed for plant growth.12

Furthermore, the increased acidity promotes the release of toxic aluminum ions ($A{l}^{3+}$) from soil minerals. These aluminum ions can further displace calcium and magnesium from soil particles, exacerbating the nutrient loss. Over time, this process depletes the soil's buffering capacity, leaving the environment increasingly sensitive to further acidification and hindering the ability of trees and other vegetation to absorb necessary nutrients.132