Manganese: The rise of an unnoticed environmental contaminant

Manganese (Mn) is one of the most abundant and dynamic elements found in natural and anthropic environments. Present in rocks, minerals, soils, water bodies, and organisms, Mn is found in several valence states (Mn2+, Mn3+, Mn4+, and Mn7+) and is reported a micronutrient for all living organisms. Its broad distribution and role as an essential nutrient hide its potential as an emergent environmental contaminant. High Mn concentrations, whether from natural (e.g., groundwaters and rocks) or anthropic (e.g., mining, environmental disasters, and air pollution) origins, have raised the concern regarding contamination of soils, waters, and organisms by Mn. Recent studies have pointed out several cases of Mn-contaminated sites worldwide, posing risks to plants, animals, and human health. Considering this emerging concern regarding Mn as a contaminant, this chapter aims to explore the sources and the main biogeochemical processes that control Mn bioavailability and dynamics within the different terrestrial geochemical compartments. In addition, this chapter summarizes some of the novel remediation strategies and alternative techniques to assess the Mn risks to human health.