Monitoring, Control, and Prevention of Excess Hg in Acid Mine Drainage (AMD) in an Abandoned Metal Sulfides Mine (SW Portugal), using Nature-Based Solutions

Abstract

This study aims to monitor the behavior of Hg in watercourses drained by a huge pile of tailings in an abandoned mine located in the Iberian Pyritic Belt (IPB), and to test the most effective low-cost technology in retaining Hg. The water collected in two consecutive years from the watercourses showed meaningful values in areas near the tailings (16-28μgg-1), above the reference value, 0.3μgg-1 (EU Regulation, 2009). Bench scale tests were conducted to evaluate the effectiveness of nature-based materials in retaining Hg by analyzing ion exchange capacity, kinetic tests, and simulating "ponds" containing different proportions of materials vs mine water.