Acid mineMine drainage (AMD) is characterized by low pH and high concentrations of heavy metalsMetal and sulfatesSulfate and poses a significant environmental challenge for miningMining-impacted watersheds. Conventional treatments for AMD involve the costly addition of limestone to neutralize acidity and precipitate contaminants. This study investigates the use of seawater—a globally available, cost-effective, and sustainable resource—as an alternative treatment for AMD. By leveraging the higher pH and the content of chlorideChloride, we aim to achieve metalMetal precipitationPrecipitation, pH neutralization, suppression of ironIron-oxidizingOxidizing bacteria and reduced reactivity of sulfideSulfide minerals through environmentally compatible mechanisms. In this experiment and study, we demonstrated that the irrigationIrrigation of seawater reduces the reactivity of sulfideSulfide minerals, such as pyritePyrite, which is the culprit of AMD. It also shows that chlorideChloride concentration at seawater level (~19 g/L) or below can successfully suppress the activity of Acidithiobacillus ferrooxidans.