ABSTRACT
The origin of Ni in soils is essential to assess human impact on the environment and is a strategic aim of soil protection policies that can ensure water and food security. Ni levels in the soil environment may be attributed to the natural weathering processes of parent materials and pedogenesis, such as, lithogenic/pedogenic origin and to various anthropogenic sources, such as, anthropogenic origin. The chemical weathering of ultramafic rocks produces soils with high levels of Ni, which in most cases commonly range in several thousands of mg kg-1. Although anthropogenic activities may also be responsible for Ni accumulation in parts of Europe, according to recent European surveys, soil Ni distribution can be attributed to natural factors to a great extent. The major anthropogenic sources of Ni to soils are the atmospheric deposition from various emissions, the mining and smelting activities, and the application of sewage sludge and phosphate fertilizers, which may contain a wide variety of heavy metals as impurities.
