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nickel
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Below is one of our free research papers on nickel. If the term paper below is not exactly what you're looking for, you can search our essay database for other topics.
INTRODUCTION
Nickel is the 28th element in the periodic table. It is a silver-white metal found in several oxidation states (ranging from -1 to +4), however, the +2 oxidation state [Ni(II)] is the most common in biological systems (DENKHAUS, SALNIKOW 2002). Nickel easily forms nickel-containing alloys, which have found an ever increasing use in modern technologies for over a hundred years now. Global input of nickel to the human environment is approximately 150 000 and 180 000 metric tonnes per year from natural and anthropogenic sources, respectively, including emissions from fossil fuel consumption, and the industrial production, use, and disposal of nickel compounds and alloys (KASPRZAK et al. 2003). SOURCES OF NICKEL Nickel is widely distributed in the environment, and can be found in air, water, and soil. Natural sources of atmospheric nickel include dusts from volcanic emissions and the weathering of rocks and soils. The level of nickel in ambient air is small (about 6-20 ng⋅m-3), but levels up to 687 150 ng Ni⋅m-3 could be present in air contaminated by anthropogenic sources. In water, nickel derives from biological cycles and solubilization of nickel compounds from soils, as well as from the sedimentation of nickel from the atmosphere. Uncontaminated water usually contain about 300 ng Ni⋅dm-3. Farm soils contain approximately 3-1000 mg Ni⋅kg-1 soil, but the Ni concentration can reach up to 24 000-53 000 mg⋅kg-1 Ni in...
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