54
Yttrium [Y, 39]
54.1 INTRODUCTION
Yttrium (Y), a silvery transition metal of group 3 in the periodic table of elements, is
chemically similar to lanthanides, and often classified as a rare earth element (REE).
It never occurs in nature as a free element. Its abundance in the Earth’s crust is within
the range of 20–33 mg/kg. Its levels in mafic rocks are lower (0.5–20 mg/kg) than
in acidic rocks (20–33 mg/kg) and in sandstone (15–25 mg/kg). It may be accumulated in some coal, up to about 170 mg/kg. The mean Y content of fly ash is about
44 mg/kg.
Yttrium occurs at +3 oxidation state and is often associated with U ores and
REE deposition, as well as with mozaite veins and pegmatites. It combines easily
with various minerals, such as oxides, carbonates, silicates, and phosphates. Its most
common minerals are xenotime (YPO 4 ) and fergusonite (YNbO 4 ).
World mine Y production (rounded), excluding the United States, in 2010 was
8900 t, of which 8800 t was produced in China, 55 t in India, and 15 t in Brazil
(USGS 2011). Recycling are small quantities of Y from laser crystals and some synthetic products. Yttrium (mainly as Y 2 O 3 ) is used in luminescence and semiconductor materials applied in various electronic devices, including lasers. It is also used in
ceramic and glass industries, and in various catalysts (e.g., in production of plastics).
Yttrium has no known biological role, and exposure to its compounds can cause
lung disease in humans.
54.2 SOILS
Worldwide Y content of soils is estimated to be about 15 mg/kg, within the range
between 2 and 100 mg/kg. The average Y contents in soils of various countries are
presented as follows (in mg/kg): China, 11–39; Japan, 5–24; California in the United
States, 17–27; Alaska in the United States, 4–100; and Poland, 7–19 (Kabata-Pendias
2011). Sandy soils contain less Y than loamy ones.
Yttrium contents in materials used for soil amendments are as follows (mean, in
mg/kg): NPK fertilizers, 14; P fertilizers, 114; sewage sludge, 11; pig manure, 2; and
fly ash, 44.
54.3 WATERS
The mean concentrations of Y in worldwide seawaters are given as 0.009 and
0.013 μg/L (Reimann and de Caritat 1998). Its average content of water of the
North Pacific is estimated to be 0.017 μg/L (Nozaki 2005). River waters of
Europe contain Y within the range of 0.05–1.49 μg/L and of the north United
States, 0.028–0.217 μg/L (Gaillardet et al. 2003). However, its concentration in some
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