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Title: Negative pH and extremely acidic mine waters from Iron Mountain, California

Journal Article · · Environmental Science and Technology
DOI:https://doi.org/10.1021/es990646v· OSTI ID:20014594

Extremely acidic mine waters with pH values as low as {minus}3.6, total dissolved metal concentrations as high as 200 g/L, and sulfate concentrations as high as 760 g/L, have been encountered underground in the Richmond Mine at Iron Mountain, CA. These are the most acidic waters known. The pH measurements were obtained by using the Pitzer method to define pH for calibration of glass membrane electrodes. The calibration of pH below 0.5 with glass membrane electrodes becomes strongly nonlinear but is reproducible to a pH as low as {minus}4. Numerous efflorescent minerals were found forming from these acid waters. These extreme acid waters were formed primarily by pyrite oxidation and concentration by evaporation with minor effects from aqueous ferrous iron oxidation and efflorescent mineral formation.

Research Organization:
Geological Survey, Boulder, CO (US)
Sponsoring Organization:
USDOE; National Science Foundation (NSF)
DOE Contract Number:
AC07-94ID13223
OSTI ID:
20014594
Journal Information:
Environmental Science and Technology, Vol. 34, Issue 2; Other Information: PBD: 15 Jan 2000; ISSN 0013-936X
Country of Publication:
United States
Language:
English