Summary #
Understanding the chemistry behind abandoned mine drainage (AMD) is important for anyone involved in watershed monitoring or treatment system design. This page introduces the key chemical concepts — acids and bases, pyrite reactions, buffering, iron oxidation states, and metals removal — and provides context for when and why this knowledge matters.
AMD Chemistry
Do I need to know this stuff?
Depending on your involvement with AMD in your watershed, you may or may not need the level of detail and complexity offered in chemistry section. If you intend on “getting into it”, then this section is appropriate. However, if the technical aspects aren’t your cup of tea, then skipping this section is probably ok.
The majority of AMD problems stem from the reactions of the mineral pyrite with water and oxygen. Not one, but a series of chemical reactions occur creating the pollutants that appear in our waterways. The specifics of where and how these reactions occur is dependent on the specifics of the geology and hydrology of the particular site. No two AMD discharges are exactly alike chemically, (In fact, we prefer the term Abandoned Mine Drainage over Acid Mine Drainage, because some discharges are actually alkaline.) The individual impacts and the options for treating discharges have much variability.
Understanding AMD chemistry requires having an appreciation for:
Acids, bases and pH
a brief overview of changing hydrogen ion concentrations in water
The reactions of pyrites
Buffering #
Ferric-Ferrous Iron
Neutralizing Acid
Removing Metals #
This section is presented at the level of a high school chemistry class. It would definitely help to have taken high school chemistry. Viewed individually, none of the concepts are that difficult. What’s more challenging is taking the individual pieces and then fitting them into a coherent whole.
AVERY BRIEF INTRODUCTION TO ACID AND ALKALINE MINE DRAINAGE Bucknell University (http://www.facstaff.bucknell.edu/kirby/AMDPrimer.html)
The Chemistry of AMD Hedin Environmental: http://www.hedinenv.com/whatisamd.htm#The%20Chemistry
Buchnell University Professor Carl Kirby, for overviews and research: http://www.facstaff.bucknell.edu/kirby/
Acid Rock Drainage at Enviromine (http://www.infomine.com/technology/enviromine/ard/home.htm)
Acid Mine Drainage Formation and Effects New Miles of Blue Streams (http://www.newmilesofbluestream.com/nmbs/WhatisAMD.htm)
Sources/Links (as provided in the source text):
- http://www.facstaff.bucknell.edu/kirby/AMDPrimer.html
- http://www.hedinenv.com/whatisamd.htm#The%20Chemistry
- http://www.facstaff.bucknell.edu/kirby/
- http://www.infomine.com/technology/enviromine/ard/home.htm
- http://www.newmilesofbluestream.com/nmbs/WhatisAMD.htm
Related Pages #
- Acids, Bases, and pH — Hydrogen ion concentrations in water
- Pyrite Reactions — The chemical reactions that create AMD
- Buffering — How watersheds resist pH changes
- How AMD is Formed (AML Basics) — The formation process
- What is AMD? (AML Basics)
Source and Last Reviewed #
Source: AMR Clearinghouse (amrclearinghouse.org). Migrated to AML-Connect. Last Reviewed: 2026-03-13.
[Admin note: Some external links in this article may be outdated. Verify before relying on them. Flag dead links for removal or replacement.]
Tags: amd, monitoring, education, practitioner
