Process-Based and Probabilistic Quantification of Co and Ni Mobilization Risks Induced by Managed Aquifer Recharge

Area of Science:

• Environmental Science
• Hydrogeology
• Geochemistry

Background:

• Managed aquifer recharge (MAR) enhances water availability but can cause adverse geochemical reactions, particularly metal mobilization when oxidant-rich waters meet reducing aquifers.
• Assessing and managing environmental risks associated with MAR-induced metal release is crucial for sustainable water management.

Purpose of the Study:

• To develop a rigorous approach for assessing and managing risks from MAR-induced metal mobilization.
• To identify and quantify hydrogeochemical drivers of metal release and mobility.
• To investigate the effectiveness of mitigation strategies for metal mobilization.

Main Methods:

• Development of a process-based reactive transport model to simulate MAR geochemical processes.
• Application of a probabilistic framework to assess uncertainty in model parameters.
• Evaluation of long-term groundwater quality changes and mitigation strategy effectiveness.

Main Results:

• Co, Ni, Zn, and Mn were found to be comobilized during pyrite oxidation.
• Metal mobility was controlled by sediment pH buffering capacity and sorption capacity.
• Tested mitigation strategies effectively reduced the risk of elevated metal concentrations.

Conclusions:

• MAR-induced metal mobilization is a significant risk requiring careful management.
• Reactive transport modeling and probabilistic frameworks are effective tools for risk assessment.
• Water treatment modifications can successfully mitigate metal release during MAR.