Divalent heavy metals and uranyl cations incorporated in calcite change its dissolution process

Area of Science:

• Environmental Science
• Geochemistry
• Mineralogy

Background:

• Calcite is a key mineral for sequestering heavy metals (HMs) and radionuclides.
• The dissolution behavior of metal- and radionuclide-incorporated calcite is not well understood.

Purpose of the Study:

• To investigate the dissolution behavior of synthesized calcite containing cadmium (Cd), cobalt (Co), nickel (Ni), zinc (Zn), and uranium (U).
• To determine how incorporated HMs and U influence calcite's dissolution and secondary mineral formation.

Main Methods:

• Synthesis of calcite crystals doped with various heavy metals and uranium.
• Experimental dissolution of doped calcite under controlled conditions.
• Analysis of dissolution products and secondary mineral precipitation.

Main Results:

• Incorporated heavy metals and uranium significantly alter calcite dissolution.
• Effects on solubility varied, showing both inhibition and enhancement depending on metal type and concentration.
• Secondary minerals including smithsonite, Co-poor aragonite, and U-rich calcite formed during dissolution.

Conclusions:

• The incorporation of HMs and U into calcite influences its dissolution rate and solubility.
• Metal incorporation can control the environmental fate of HMs, uranium, calcite, and carbon dioxide.
• Understanding these interactions is crucial for predicting contaminant mobility and mineral behavior.