acid rock drainage
phrasePronunciation: /ˈæsɪd rɑk ˈdreɪnɪdʒ/
Also written as: ARD — Acid Rock Drainage
The formation of acidic water when sulfide minerals in rock are exposed to oxygen and water. This creates ongoing pollution that can persist for centuries if left untreated.
Full Definition
Acid rock drainage is a geochemical process that occurs when sulfide-bearing minerals, particularly pyrite, are exposed to oxygen and water through mining activities, resulting in the formation of sulfuric acid and dissolved metals. This process can continue for decades or centuries, producing acidic leachate that contaminates groundwater and surface water with heavy metals and low pH conditions toxic to aquatic life. In abandoned mine reclamation, acid rock drainage represents one of the most persistent and expensive environmental challenges, often requiring long-term treatment systems and perpetual care. Prevention strategies include limiting oxygen and water contact with sulfide minerals through covers, sealing, or underwater disposal.
Plain English
When rocks containing sulfur get wet and exposed to air, they create acid that pollutes water with metals and makes it harmful to fish and other life.
In Editorial Context
A central environmental concern in mine reclamation stories, often requiring explanation of the underlying chemistry and long-term consequences, frequently illustrated with orange-colored stream photos and water quality data.
Etymology & History
Scientific understanding developed as mining expanded and environmental awareness grew, leading to recognition that sulfide oxidation was the primary cause of mining-related water pollution.
Previously called 'acid mine drainage' but broadened to include natural acid drainage from sulfide-bearing rocks not related to mining.
Usage
"The abandoned copper mine's acid rock drainage continued to contaminate the watershed twenty years after closure, necessitating construction of a limestone treatment system."
Usage note: Use ARD acronym only after spelling out the full term; distinguish from acid mine drainage (AMD) which specifically refers to mining-related sources.
Context: environmental assessments, water quality reports, reclamation planning, scientific literature
Region: international
Also known as
Contrasted with
Don't confuse with
Acid mine drainage (AMD) specifically refers to mining-related acid generation, while acid rock drainage (ARD) includes natural processes; both terms are sometimes used interchangeably in practice.