Heavy Metal Contamination of Soil, Its Risk Assessment and Bioremediation

In this review paper, there are 3 subjects discussed such as heavy metals contamination in soil, human risk assessment around metal mine areas, and bioremediation of heavy metals-contaminated sites. Heavy metal contamination in soil is classified into two categories depending on sources; one is the natural enrichment of heavy metals in soil from high background source rocks, and the other is anthropogenic contamination from the non-point and point sources. Some potentially toxic elements are highly enriched in areas covered with black shale. The level and dispersion patterns of As, Mo, Cd, U, and Se in soil underlain by black shale were discussed in regional and local scales. Heavy metals contamination in the areas of abandoned Au-Ag and base metal mines was investigated and the results of each mine site were compared. The concept of pollution index (PI) of soils gives important information on the extent and degree of multi-element contamination and can be applied to the evaluation of soils prior to their agricultural use and remediations. Pollution level of Pt in dusts and soils from various traffic volume urban roads in and around Seoul were presented. Environmental geo- chemical surveys were undertaken around some abandoned metal mine areas to assess the risk of adverse health effects on human exposure to heavy metals influenced by previous mining activities. Two case studies on the biosorption of cationic heavy metals to microbial cells, and microbial redox transformation of arsenic are introduced to present their potential for the bioremediation of contaminated field sites.