Zinc [Zn, 30]

Zinc (Zn) is a metal of group 15 in the periodic table of elements, which also contains cadmium and mercury. Its abundance in the Earth’s crust is about 75 mg/kg, within the given range of 50–80 mg/kg. Average Zn contents of worldwide soils range from about 30 to 100 mg/kg. Its amounts are, in general, closely associated with soil texture, and usually the lowest are in light sandy soils. In lakes, rivers, and estuaries, Zn is bound by hydroxides, clay minerals, and other sediment materials. General levels of Zn in the atmosphere are relatively fairly constant. Its worldwide median concentrations are estimated to be 0.04 and 900 ng/m3, for remote and polluted regions, respectively. Mobile species of Zn are readily available to plants, and its uptake is reported to be linear with metal concentration in nutrient solutions and in soils. Zinc is vital for many biological functions, supporting normal growth and development in pregnancy, childhood, and adolescence.