Element

Chromium-Cr

Chromium-Cr

Chromium (Cr) is a polyvalent element and can exist in several distinct oxidation states, but only trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)] occur with any frequency in the natural environment. The...

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Selenium

Selenium

Although selenium is a component of many minerals, it is only the seventieth most abundant element in the earth’s crust and occurs mostly in small crystals and in small quantities. It typically only occurs at elevated...

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Arsenic

Arsenic

Arsenic is naturally-occurring throughout the environment and also widely used as a preservative for treated wood and as a pesticide in fields where we grow our food. Because of its chemical nature, it is frequently...

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Mercury

Mercury

Mercury is not very abundant in the planet’s crust; however, even modest increases in the quantity of mercury being introduced into the global environment is a matter of considerable and growing concern. Mercury...

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