Technical guidance on normal levels of contaminants in Welsh soil : Nickel (Ni) : January 2013

Nickel (Ni) is a metallic element with an affinity for iron (Fe) and sulphur (S) and has a reported abundance in the Earth’s crust of about 20 mg/kg and so it is referred to as a trace element. The rocks with the highest Ni contents are those with a very “mafic” composition (i.e. rich in Fe and Mg minerals) such as serpentinites (1400 - 2000 mg/kg). Rocks with the lowest Ni contents are granites, sandstones and limestones (5 - 15 mg/kg). This element is considered as a contaminant because some Ni compounds are carcinogenic and Ni can cause allergic skin reactions in some individuals.