Acid-mine discharges

The Eh and pH of iron-rich natural waters, most of which contain suspended ferric oxyhydroxides, places these waters on the ferric or ferrous species-ferric oxyhydroxide boundary. Acid-mine discharges usually have pHs between 2 and 5 and Ehs from within the Fe3+ field down to zero volts. Iron-rich ground waters are usually on the same boundary, with pHs between 5 and 8 and Ehs from +0.3 to —0.1 volt. 

AQUATIC PLANTS Euglena sp. From acidic mine tailings waste discharges 143 DW Max. 410 DW 1... 

From acidic mine taiiings waste discharges (0.9 mg Zn/L, Max. 3.3 mg/L)... 

Alpers C. N., Nordstrom D. K., and Burchard J. M. (1992) Compilation and Interpretation of Water Quality and Discharge Data for Acid Mine Waters at Iron Mountain, Shasta County, California, 1940—91. US Geol. Surv. Water-Resour. Invest. Report 91-4160, 173pp. 

Walter A. L., Frind E. O., Blowes D. W., Ptacek C. J., and Molson J. W. (1994b) Modelling of multicomponent reactive transport in groundwater 2. Metal mobility in aquifers impacted by acidic mine tailings discharge. Water Re sour. Res. 30, 3149-3158. 

How and why do changes occur in the concentrations of acidity and of dissolved metals and other species in streams draining acid mine drainage country as a function of stream discharge ... 

It seems likely that there are some natural aqueous systems, especially those impacted by acidic precipitation or discharges of acid mine drainage, in which polymeric Al species like those studied in this work will be formed. Most of these systems will contain solid surfaces, and a tendency for aluminum polymeric species to nucleate and precipitate on certain types of mineral surfaces was documented by Brown and Hem (21). Conclusions relevant to the probable course of the aluminum hydroxide polymerization process in natural water may be summarized as follows ... 

Acid mine drainage from underground mines generally appears at the surface as point discharges (Bell et al., 2002). Acid mine drainage also can develop from surface sources such as mine waste. A major source of acid mine drainage may result from the closure of a mine. 

With rare exception all source waters have relatively low lead. Ground-waters generally have very low lead and river waters sometimes contain detectable lead from industrial discharges or acidic mine drainage. However, even in these cases, much of the lead is removed by water treatment. 

The most important control on the chemistry of drainage from mineralized areas (once we assume access of oxygen to the sulfide minerals) is the nature of the nonsulfide minerals available to react with the drainage before it discharges to the surface (e.g., Sherlock et al., 1995). These minerals include gangue minerals in the ore, the minerals making up the country rock, and the minerals found in mine dumps. The drainage chemistry of areas in which these minerals have the ability to neutralize acid differs sharply from that of areas in which they do not. 

Acidity problems tend to be localized in bodies of water near industrial operations that discharge acidic materials or near active or abandoned mines. Acids form when water flows through all kinds of mines, including coal mines and mines for the extraction of various metals. Probably the most common acid-forming process in such cases occurs when iron pyrites (FeS2), found in coal seams and in many metal mines, is oxidized by atmospheric oxygen or oxygen dissolved in water to produce iron(II) sulfate ... 

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