Nickel is a silvery-white, hard, and ductile metal that can take a high polish. It is ferromagnetic and exhibits high resistance to corrosion and oxidation. These properties make it valuable in various applications across natural environments and human-made products.
Natural Sources of Nickel
Nickel is a naturally occurring element widely distributed within the Earth. It is the 24th most abundant element in the Earth’s crust. Significant concentrations are found in the Earth’s core. In the Earth’s crust, nickel primarily occurs as oxides, sulfides, and silicate minerals.
Geological formations rich in nickel include mafic and ultramafic igneous rocks like peridotite and gabbro. Intense weathering of these rocks in humid, tropical, or subtropical conditions forms laterite deposits, a major terrestrial nickel resource. These deposits are found in New Caledonia, Australia, the Philippines, and Indonesia.
Nickel is present in extraterrestrial materials, such as meteorites. Most meteorites contain iron-nickel alloys. Iron meteorites, primarily composed of these alloys, contain 5-30% nickel. This high nickel content can distinguish meteoritic iron from human-made iron.
Nickel in Everyday Items and Industrial Uses
Nickel’s properties, including corrosion resistance, strength, and heat resistance, make it highly valued in industrial applications and everyday products. The largest consumption of nickel is in stainless steel production, accounting for about 68% of world production. Nickel enhances stainless steel’s corrosion resistance, ductility, and weldability, making it suitable for kitchenware, medical instruments, and construction materials.
Nickel is a component in various other alloys, such as superalloys used in aerospace for jet engines and gas turbines due to their ability to withstand high temperatures and corrosive environments. Monel, an alloy of nickel and copper, offers excellent resistance to seawater corrosion, finding use in marine engineering and chemical processing. Nickel is also used in coinage, contributing to coin durability and appearance.
Nickel plays a role in various battery types, including nickel-cadmium (Ni-Cd) and nickel-metal hydride (Ni-MH) batteries. It is also a component in the cathode materials of some lithium-ion batteries, particularly those used in electric vehicles. Electroplating processes use nickel to apply a protective and decorative coating to other metals. Nickel compounds and alloys serve as catalysts in chemical reactions, such as the hydrogenation of oils and the reforming of hydrocarbons. Nickel catalysts are also explored for hydrogen production through water electrolysis.
Nickel’s Presence in the Environment
Nickel is widely distributed throughout environmental compartments: air, water, and soil. Its presence stems from both natural processes and human activities.
Natural sources contributing to environmental nickel levels include weathering of nickel-containing rocks and soils, volcanic emissions, and wind-blown dust. Forest fires and sea salt spray also release nickel into the atmosphere.
Human activities contribute to nickel’s environmental distribution. Industrial emissions from metal manufacturing, mining, and smelting operations release nickel into the air, water, and soil. The combustion of fossil fuels and waste incineration also introduces nickel compounds into the atmosphere. Waste disposal and certain products like stainless steel kitchen utensils and inexpensive jewelry can lead to nickel’s presence in the environment.
In the air, nickel exists as particulate matter. In aquatic environments, nickel can be found as dissolved ions, or bound to suspended solids, organic matter, and clay particles. Soil nickel concentrations vary widely depending on the parent rock and human input.
Nickel in Biological Systems
Nickel is a trace element that plays a role in biological processes within living organisms. For plants, nickel is an essential element due to its function in the enzyme urease. While the requirement for nickel in plants is very low, its absence can impact growth.
Nickel is present in small amounts in animals and humans, acquired through diet and water. Foods such as vegetables, fruits, grains, cocoa beans, and seafood contain nickel.
Some plants, known as hyperaccumulators, absorb and store high concentrations of nickel in their tissues. While nickel is essential in trace amounts, elevated levels can lead to adverse effects in both plants and animals.