Contaminant dynamics: Key to remedial performance and regulatory relief

Remediation results depend on thorough consideration of all the forces that influence contaminant behavior, including how the contaminant is distributed and the site's hydrogeology, as well as the physical, chemical, and biological factors involved in contaminant mobility and persistence. This information supports a cleanup project's initial investigation, helping decide the goals of the later remediation method, the usefulness of specific technologies, and the method's ultimate performance. This article discusses how the principal environmental and chemical processes influence contaminant fate and transport and explores four case histories that illustrate how that influence can help predict whether a project's goals are achievable, whether the project is needed at all, and whether those goals were actually achieved.     

Phylogenetic analysis of hyperaccumulator plant species for heavy metals and polycyclic aromatic hydrocarbons

Increasing concentration of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in the soil may impose a serious threat to living organisms due to their toxicity and the ability to accumulate in plant tissues. The present review focuses on the phylogenetic relationships, sources, biotransformation and accumulation potential of hyperaccumulators for the priority HMs and PAHs. This review provides an opportunity to reveal the role of hyperaccumulators in removal of HMs and PAHs from soils, to understand the relationships between pollutants and their influence on the environment and to find potential plant species for soil remediation. The phylogenetic analysis results showed that the hyperaccumulators of some chemicals (Co, Cu, Mn, Ni, Zn, Cd) are clustered on the evolutionary tree and that the ability to hyperaccumulate different pollutants can be correlated either positively (Cd–Zn, Pb–Zn, Co–Cu, Cd–Pb) or negatively (Cu–PAHs, Co–Cd, Co–PAHs, Ni–PAHs, Cu–Ni, Mn–PAHs). Further research needs to be extended on the focus of commercializing the techniques including the native hyperaccumulators to remediate the highly contaminated soils.