Nickel in soils: A review of its distribution and impacts

Nickel is generally uniformly distributed in the soil profile and typical soil nickel contents vary widely based on the parent rock, with elevated levels at surface soils been associated with soil- forming processes and anthropogenic contamination principally ascribed to agricultural and industrial activities. Major concern for the impact and distribution of nickel in soils arises apparently from the role of soil as an ultimate sink for heavy metals and the consequence transfer through the food- chain to crops, fruits and vegetables grown in contaminated soils and their possible consumption by animals or humans. Furthermore, in this review the role of nickel as a nutritional trace element for some animals, micro- organisms and plants, and its implicative deficiency or toxicity symptoms that may arise from the presence of too little or too much nickel is also of interest.    Key words: Nickel, heavy metal, soil, nutritional element.