Nickel - The Risk Assessment Information System

Nickel is released to the environment through the extraction, processing and use of nickel
compounds (HSDB). The single largest use of nickel is in the manufacture of stainless steels
(Alloway, 1990). Nickel is also used in the production of alloys with other metals such as iron,
copper, chromium, and zinc (ATSDR, 1988; HSDB). Other major uses are in electroplating
alloys, nickel-cadmium batteries, electronic components, fuel cells, specialty ceramics, magnets,
specialty chemicals, filters for gases, hydrogenation of fats, petroleum products, preparation of
colored pigments and for color stabilization of color copy paper (ATSDR, 1988; Alloway, 1990).
Nickel may also be released from natural sources, such as volcanoes, windblown dusts, the
weathering of rocks, forest fires, and decaying vegetation (Davies, 1974; HSDB).
In the atmosphere, nickel is expected to exist in the particulate phase and is released to soils
through wet and dry deposition. The species of nickel present in deposition include soil minerals,
oxides and sulphates (Alloway, 1990). The largest anthropogenic sources of nickel to the
atmosphere result from the burning of fuel and residual oils followed by diesel exhaust, the
combustion of coal and nickel mining and smelting (Alloway, 1990).
Background concentrations reported
for many metals in U.S. soils are
described in Attachment 1-4 of the
Eco-SSL guidance (U.S. EPA, 2003).
Figure 2.1 provides a plot of the
typical background concentrations of
nickel in U.S. soils in the eastern and
western portions of the country.
In soils, nickel may be present as
soluble compounds including
chlorides and nitrates, and insoluble
compounds such as oxides and
sulfides. Soluble nickel compounds
tend to exhibit greater mobility than
insoluble nickel compounds (Dean,
1985; HSDB). The degree of mobility
is influenced by the formation of complexes in the presence of organic
substances and sulfates (Anderson and Christensen, 1988). The distribution
of nickel between solid and solution phases is primarily controlled by pH
with secondary factors being clay content, and the amount of hydrous iron
and manganese oxides. Soluble nickel increases with decreases in pH.
Increases in metal loading and cation exchange capacity (CEC) increase the
amount of metal adsorbed by soil (Alloway, 1990). Due to low vapor
Conc (mg/kg dw)
60
50
40
30
20
10
0
East West
Figure 2.1 Typical Background
Concentrations of Nickel
in U.S. Soils
Maximum
pressures, most nickel compounds are not expected to volatilize from moist or dry soil surfaces,
with one notable exception being nickel carbonyl (Ohe, 1976; HSDB). The concentration of
nickel in plants generally reflects the concentration in soil although the relationship is more
related to soluble and exchanged forms of nickel. Factors that increase solubility and
Eco-SSL for Nickel 2
March 2007
95th
75th
50th
25th
5th Percentile