Nickel [Ni, 28]

Nickel is a metal of group 10 in the periodic table of elements, which also contains Pd and Pt. Its mean abundance in the Earth’s crust is around 20 mg/kg. The contents of Ni in ultramafic rocks are highly elevated and range from 1400 to 2000 mg/kg. Organic matter (OM) and clay minerals exhibit a strong ability to absorb nickel; thus, it may be concentrated in some coals and oil, as well as in bottom sediments rich in OM. Nickel is easily mobilized during weathering processes and may easily migrate with water down soil profiles. Nickel is considered as a serious pollutant that is released from metal-processing plant and from the combustion of coal and oil. High cation-exchange capacity values of soils may limit its availability to plants. Nickel deficiency is manifested primarily in the liver functions, including abnormal cellular morphology, oxidative metabolism, and increases and decreases in lipid levels.