Which of the following methods is NOT commonly used for groundwater remediation?

Ocean desalination is not commonly used for groundwater remediation because it is primarily a process aimed at converting seawater into freshwater for drinking and irrigation purposes, rather than addressing contaminated groundwater directly. Groundwater remediation focuses on techniques that specifically target the removal, treatment, or containment of pollutants in groundwater aquifers.

In contrast, pump and treat is a widely accepted method that involves extracting contaminated groundwater, treating it to remove pollutants, and then either discharging it or re-injecting it back into the aquifer. Bioremediation employs biological agents, such as bacteria or plants, to either degrade or remove contaminants from groundwater, making it another recognized approach for addressing groundwater pollution. Natural attenuation relies on natural processes within the environment, such as dilution, dispersion, and biodegradation, to reduce contamination levels in groundwater over time. Thus, while methods like pump and treat, bioremediation, and natural attenuation directly address contamination in groundwater, ocean desalination does not focus on this issue.