The Origin of Aluminum Flocs in Polluted Streams

About 240,000 square kilometers of Earth's surface is disrupted by mining, which creates watersheds that are polluted by acidity, aluminum, and heavy metals. Mixing of acidic effluent from old mines and acidic soils into waters with a higher pH causes precipitation of amorphous aluminum oxyhydr...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2002-09, Vol.297 (5590), p.2245-2247
Main Authors: Furrer, Gerhard, Phillips, Brian L., Ulrich, Kai-Uwe, Pöthig, Rosemarie, Casey, William H.
Format: Article
Language:English
Subjects:
Acid deposition
Acid mine drainage
Acid rain
Aluminum
Aluminum (Metal)
Aluminum mining
Applied geophysics
Earth sciences
Earth, ocean, space
Exact sciences and technology
Freshwater
Gels
Geochemistry
Internal geophysics
Metal geology
Metallic and non-metallic deposits
Mineral industry
Mineralogy
Mining industry
Molecules
Non silicates
Organic Chemistry
Rivers
Streams
Surface water
Switzerland
Water pollution
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Summary:About 240,000 square kilometers of Earth's surface is disrupted by mining, which creates watersheds that are polluted by acidity, aluminum, and heavy metals. Mixing of acidic effluent from old mines and acidic soils into waters with a higher pH causes precipitation of amorphous aluminum oxyhydroxide flocs that move in streams as suspended solids and transport adsorbed contaminants. On the basis of samples from nine streams, we show that these flocs probably form from aggregation of the$\varepsilon-Keggin$polyoxocation$AlO_{4}Al_{12}(OH)_{24}(H_2O)_{12}^{7+}(aq) (Al_{13})$, because all of the flocs contain distinct$Al(O)_4$centers similar to that of the$Al_{13}$nanocluster.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1076505