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==Acronym==
'''Acid mine drainage''' ('''AMD''') refers to the outflow of [[acid]]ic water from (usually) abandoned [[metal]] [[Mining|mines]]. In many localities the liquor that drains from [[coal]] stocks, coal handling facilities, coal washeries, and even coal waste tips can be highly acidic, and in such cases it is treated as acid mine drainage.
Is it offenseive to use BUPC in the article instead of writing it out every time? Usually acronyms are defined at the beginning, then used throughout. It would make it a lot easier to read. [[User:Cunado19|<font color="#d14c04">'''Cuñado'''</font>]] [[image:Bahaitemplatestar.png|20px]] - [[User talk:Cunado19|<font size="-3">Talk</font>]] 20:40, 17 November 2005 (UTC)
==Occurrence==
:Thanks for fixing that, and for the rest of your work in the Garden. [[User:Jeffmichaud]]
Subsurface mining often progresses below the water table, in which case water must be constantly pumped out of the mine in order to prevent flooding. When a mine is abandoned, the pumping will cease and the water table will return to its former position, flooding the mine. The introduction of water is the initial step in most acid mine drainage situations. [[Tailings]] piles or ponds may also be a source of acid mine drainage.
==Removed==
Metal mines may generate highly acidic mine discharges where the [[ore]] is a [[sulfide]] or is associated with [[pyrite]]s. In these cases the predominant metal [[ion]] may not be [[iron]] but may be [[zinc]], [[copper]], or [[nickel]]. The most commonly mined ore of copper, [[chalcopyrite]], is itself a pyrite and occurs with a range of other sulfides. Thus, [[copper extraction|copper mines]] are often major culprits of AMD.
Why was this removed?
Metal sulfides (often pyrite) newly exposed to air and water are broken down into metal ions and [[sulfuric acid]] by colonies of [[bacterium|bacteria]] and [[archaea]]. These microbes, called [[extremophile]]s for their ability to survive in harsh conditions, occur naturally in the rock, but limited water and air supplies usually keep their numbers low. Special extremophiles known as [[acidophile]]s especially favor the low [[pH]] levels of abandoned mines. ''[[Thiobacillus ferrooxidans]]'' in particular has been identified as a key contributor to the [[oxidation]] of pyrites [http://www.mines.edu/fs_home/jhoran/ch126/microbia.htm].
:''The Bahá'ís Under the Provision of the Covenant regard an adopted relationship from 'Abdu'l Baha, to Mason Remey, to Pepe Remey, to Neal Chase. None of these are blood relationships, and the only legal adoption was Mason Remey adopting Pepe Remey. Leland Jensen is not seen as part of this line of Guardians, but still traces his lineage to [[David|King David]].''
Biotic processes far outpace the slower, abiotic process of pyrite oxidation.
If it is not accurate that is one thing, but if it is accurate, it is entirely relevant. [[User:Cunado19|<font color="#d14c04">'''Cuñado'''</font>]] [[image:Bahaitemplatestar.png|20px]] - [[User talk:Cunado19|<font size="-3">Talk</font>]] 18:18, 18 November 2005 (UTC)
==Chemistry==
:not accurate (the adoptions were all legal, and Jensen had nothing to do with Guardiaships or David) and was sort of hanging there relevent to nothing before or after it. I'll get to all that stuff;This page is still a WIP.
The chemistry of oxidation of pyrites, the production of [[ferrous]] ions and subsequently [[ferric]] ions, is very complex, and this complexity has considerably inhibited the design of effective treatment options.
::*Abdu'l Baha to Remey --> not legal
Although a host of chemical processes contribute to AMD, pyrite oxidation is by far the greatest contributor. A general equation for this process is:
::*Remey to Pepe --> legal
::*Pepe to Chase --> not legal
::These are not questionable facts. I don't know any details between Remey to Pepe, but if you're disputing the others then you need some serious references, like signed documents. Jensen also traces lineage to King David, you wrote it yourself in one of the pages. [[User:Cunado19|<font color="#d14c04">'''Cuñado'''</font>]] [[image:Bahaitemplatestar.png|20px]] - [[User talk:Cunado19|<font size="-3">Talk</font>]] 02:42, 20 November 2005 (UTC)
I never wrote anything about Doc's lineage from David. Others keep reverting what I write about his beliefs back to an obscure statement which is how it appears in its current version on the Baha'i Divisions page. Abdu'l-Baha's adoption of Mason was legal and so was Pepe's and Neal. Obviously you "don't know any details" on any of these things. If you don't you shouldn't be adding things to pages that you don't know about and can't reference. You know better. I'll reference all those things when I add them to the summary. [User:Jeffmichaud]
:4FeS<sub>2</sub>(s) + 14O<sub>2</sub>(g) + 4H<sub>2</sub>O(l) → 4Fe<sup>2+</sup>(aq) + 8SO<sub>4</sub><sup>2-</sup>(aq) + 8H<sup>+</sup>(aq)
The solid pyrite, when introduced to oxygen and water, is catalyzed to form [[Iron(II)]] ions, [[sulfate]] ions, and [[hydrogen]] ions. The hydrogen ions bind to the sulfate ions to produce [[sulfuric acid]].
==Effects==
===Effects on pH===
In some AMD systems temperatures reach 120 degrees Fahrenheit (50 °C), and the pH can be as low as -3.6[http://ca.water.usgs.gov/water_quality/acid/]. AMD-causing organisms can thrive in waters with pH very close to zero. Negative pH occurs when water evaporates from already acidic pools thereby increasing the concentration of hydrogen ions.
About half of the [[coal mine]] discharges in [[Pennsylvania]] are acidic, with pH <5. This AMD has especially been a hindrance to the completion of the construction of [[Interstate 99]] near [[State College, Pennsylvania|State College]].
===Yellow boy===
[[Image:Iron hydroxide precipitate in stream.jpg|thumb|right|200px|Yellow boy in a stream receiving acid drainage from surface coal mining.]]
When the pH of AMD is raised past 3, either through contact with fresh water or [[Neutralization|neutralizing]] minerals, soluble Iron(III) ions hydrolize to form [[Iron(III) hydroxide]], a yellow-orange solid colloquially known as [[Yellow boy]]. Yellow boy discolors water and smothers plant and animal life on the streambed, disrupting [[stream]] [[ecosystem]]s. The process also produces additional hydrogen ions, which can further decrease pH.
===Heavy metal contamination===
Many acid mine discharges also contain elevated levels of toxic metals, especially nickel and copper with lower levels of a range of other heavy metal ions such as [[lead]], [[arsenic]], and [[manganese]]. In the coal belt around the south [[Wales]] valleys in the [[UK]] highly acidic nickel-rich discharges from coal stocking sites have proved to be particularly troublesome.
==Treatment==
===Oversight===
In the [[United Kingdom]], many discharges from abandoned mines are exempt from regulatory control. In such cases the [[Environment Agency]] working with partners has provided some innovative solutions, including [[constructed wetland]] solutions such as on the [[River Pelena]] in the valley of the [[River Afan]] near [[Port Talbot]].
Although abandoned underground mines produce most of the AMD, some recently mined and reclaimed surface mines have produced AMD and have degraded local ground-water and surface-water resources. Acidic water produced at active mines must be neutralized to achieve pH 6-9 before discharge from a mine site to a stream is permitted.
In Canada, work to reduce the effects of AMD is concentrated under the Mine Environment Neutral Drainage (MEND) program. Total liability from acid mine drainage is estimated to be between $2 billion and $5 billion CAD [http://www.nrcan.gc.ca/mms/canmet-mtb/mmsl-lmsm/enviro/effluents/effspecserv-e.htm]. Over a period of eight years, MEND claims to have reduced AMD liability by up to $400 million CAD, from an investment of $17.5 million CAD [http://www.nrcan.gc.ca/mms/canmet-mtb/mmsl-lmsm/mend/default_e.htm].
===Methods===
====Carbonate neutralization====
Generally, [[limestone]] or other [[Calcium|calcareous]] [[Stratum|strata]] that could neutralize acid are lacking or deficient at sites that produce acidic mine drainage. Limestone chips may be introduced into sites to create a neutralizing effect. Where [[limestone]] has been used, such as at [[Cwm Rheidol]] in mid [[Wales]], the positive impact has been much less than anticipated because of the creation of an insoluble [[calcium sulfate]] layer on the limestone chips, blinding the material and preventing further neutralization.
====Ion exchange====
[[Ion exchange|Cation exchange]] processes were investigated as a potential treatment for AMD. Not only would ion exchangers remove potentially toxic heavy metals from mine runoff, there was also the possibility of turning a profit off of the recovered metals. However, the cost of ion exchange materials compared to the relatively small returns, as well as the inability of current technology to efficiently deal with the vast amounts of mine discharge, renders this solution unrealistic at present.
====Constructed wetlands====
[[Constructed wetland]]s systems have shown promise as a more cost-effective treatment alternative to artificial treatment plants. A spectrum of bacteria and archaea, in consortium with wetland plants, may be used to filter out heavy metals and raise pH. Anaerobic bacteria in particular are known to be capable of reverting sulfate ions into sulfide ions. These sulfide ions can then bind with heavy metal ions, precipitating heavy metals out of solution and effectively reversing the entire process.
Interestingly enough, ''T. ferrooxidans'' - the very bacteria which appears to be the problem - has also been shown to be effective in treating heavy metals in constructed wetland treatment systems.
The attractiveness of a constructed wetlands solution lies in its passivity - building an artificial wetlands is a relatively cheap one-time investment which continuously works to reduce acidity and heavy metal concentration. Although promising, constructed wetlands take much time to completely cleanse an area, and are simply not enough to deal with extensively polluted discharge. Constructed wetland effluent often requires additional treatment to completely stabilize pH. Also, the products of bacterial processes are unstable when exposed to oxygen, and require special disposal to ensure no further contamination. Other issues include seasonal variation in the activity of cleansing organisms, as well as the lack of a practical passive means of moving mine discharge through the most efficient regions of purification.
==List of acid mine drainage sites worldwide==
This list will never be complete, but it hints at the enormity of the problem. It includes both mines producing AMD and river systems significantly affected by such drainage.
===North America===
*Iron Mountain Mine, [[Shasta County, California]], [[USA]]
*[[Clinch River | Clinch]]-[[Powell River (Virginia) | Powell]] River system, [[Virginia]] and [[Tennessee]], USA
*[[Berkeley Pit]] [[superfund]] site, covering the [[Clark Fork River]] and 50,000 acres (200 km²) in and around [[Butte, Montana]], USA
*[http://www.dep.state.pa.us/dep/deputate/minres/bamr/amd/amd_abatement_projects.htm Various Coal Mines], Central [[Pennsylvania]], USA
*[http://www.ccrs.nrcan.gc.ca/ccrs/rd/apps/geo/mine/uranium_e.html Pronto mine tailings site, [[Elliot Lake]] area, [[Ontario]], Canada
===Europe===
*Cwm Rheidol, [[Wales]]
*Aznalcollar mine on the Agrio River, [[Spain]]
===Oceania===
*[[Buller (district), New Zealand | Buller]] coalfield in the north-west of the South Island, [[New Zealand]]
==See also==
*[[Mining]]
*[[Environmental Protection Agency]]
*[[Environment Agency]]
*[[Clean Water Act]]
*[[Bioleaching]]
==External links==
*[http://www.dep.state.pa.us/dep/deputate/minres/bamr/amd/science_of_amd.htm The Science of Acid Mine Drainage and Passive Treatment]
*[http://www.mines.edu/fs_home/jhoran/ch126/yellow.htm Pictures of yellow boy]
*[http://geology.er.usgs.gov/eastern/environment/drainage.html USGS Mine Drainage]
*[http://pa.water.usgs.gov/projects/amd/ Coal-Mine-Drainage Projects in Pennsylvania]
*[http://www.amrclearinghouse.org/Sub/AMDbasics/ZZoverview.htm AMRClearinghouse.org]
*[http://www.miningwatch.org/emcbc/publications/amd_water.htm Environmental Mining Council of British Columbia]
*[http://ca.water.usgs.gov/water_quality/acid/ World's Most Acidic Waters are Found Near Redding, California (pH -3.6)]
*[ http://www.mines.edu/fs_home/jhoran/ch126/amd.htm Overview of chemical processes involved]]
*[http://www.parliament.uk/commons/lib/research/rp99/rp99-010.pdf Assessment of treatment methods (PDF)]
[[Category:Ecology]]
[[Category:Mining]]
[[Category:Environmental science]]
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