Geoscience Reference
In-Depth Information
Nickel, which is emitted into the environment from both natural and human-
made sources, is circulated throughout all environmental compartments by means
of chemical and physical processes and is biologically transported by living
organisms. Nickel enters groundwater and surface waters from erosion and dis-
solution of rocks and soils, as well as from biological cycles, atmospheric fallout,
industrial processes, and waste disposal. Nickel leached from dump sites can
contribute to nickel contamination of an aquifer, with potential ecotoxicity. Acid
rain has a tendency to mobilize nickel from soil and increase nickel concentrations
in groundwater, leading eventually to increased uptake and possible toxicity in
microorganisms, plants, and animals.
Depending on the soil type, nickel may exhibit a high mobility within the soil
profile, finally reaching groundwater, rivers, and lakes. Terrestrial plants take up
nickel from soil, primarily via the roots. The amount of nickel uptake from soil
depends on various geochemical and physical parameters, including soil type, soil
pH and humidity, the organic matter content of the soil, and the concentration of
extractable nickel. Drinking water generally contains less than 10 lg/L of nickel,
but nickel may occasionally be released from plumbing fittings, resulting in
concentrations of up to 500 lg/L.
In terms of human health, nickel carbonyl is the most acutely toxic nickel
compound. The effects of acute nickel carbonyl poisoning include frontal head-
ache, vertigo, nausea, vomiting, insomnia, and irritability, followed by pulmonary
symptoms similar to those of viral pneumonia. Pathological pulmonary lesions
include hemorrhage, edema, and cellular derangement. The liver, kidneys, adrenal
glands, spleen, and brain also are affected. Cases of nickel poisoning have been
reported in patients dialyzed with nickel-contaminated dialysate and in electrop-
laters who accidentally ingested water contaminated by nickel sulfate and nickel
chloride.
Chronic effects such as rhinitis, sinusitis, nasal septal perforations, and asthma
have been reported in nickel refinery and nickel-plating workers. Some authors
reported pulmonary changes with fibrosis in workers inhaling nickel dust. In
addition, nasal dysplasia has been reported in nickel refinery workers. Nickel
contact hypersensitivity has been documented extensively in both the general
population and in a number of occupations in which workers were exposed to
soluble nickel compounds. Very high risks of lung and nasal cancer have been
reported in nickel refinery workers employed in the high-temperature roasting of
sulfide ores, involving substantial exposure to nickel subsulfide, oxide, and per-
haps sulfate. Similar risks have been reported in processes involving exposure to
soluble nickel (electrolysis, copper sulfate extraction, hydrometallurgy), often
combined with some nickel oxide exposure, but with low nickel subsulfide
exposure.
