Assessment of heavy metal pollution from anthropogenic activities and remediation strategies: A review

Heavy metal pollution is a nefarious issue with implications for life. Heavy metals are natural occurring elements, having both natural and anthropogenic sources. The latter are however the most significant, releasing greater amounts of these pollutants in more toxic and mobile forms. Their chemistry and dynamics in the ecosystems are presented, and the relation to the pollution problematic thereof is discussed. The concentration of heavy metals in several sites, assessed in water, soil and sediment samples, affected by different pollution sources are reviewed. These evidence how human activities impact natural media and how the pollution spreads. The pollution in each media is assessed by the concentration relative to drinking and irrigation water guidelines, and by the geoaccumulation index of soils and sediments. It is found that ore extraction and processing and metallurgical industries stand atop the most polluting sources. Given the dynamics of heavy metal cations and that, most of these are released in liquid effluents, wastewater treatment techniques for the removal of heavy metals are also surveyed and critically discussed. Economic viability at a large municipal scale and the ability to comply with strict regulations are the determining factors in the selection of these techniques. A critical discussion on the viability of such techniques is made, reviewing some literature studies and commenting on their applicability on the previously found polluted media.