Chapter eight - Role and importance of microorganisms in plant nutrition and remediation of potentially toxic elements contaminated soils

Abstract

Potentially toxic elements (PTEs) may be toxic at low concentrations and can damage living organisms as well as being transferred through the food chain. PTEs remain in soils for a long time, and may directly affect on agricultural products and surface water and groundwater, thus endangering human and environmental health. After observing two cases, the researchers may have started using microorganisms for the remediation PTEs contaminated soils: (1) the presence of resistant microorganisms in contaminated soils and, (2) the comparison of contamination changes in microorganisms-rich soils with microorganisms-poor soils. Bioremediation is one of the ways to remediate contaminated soils. For example, bacteria resistant to metal contaminated environments can be used to reduce PTEs mobility. In fact, along with various methods for the remediation of soils contaminated with PTEs, bioremediation is a cost-effective and eco-friendly method. This biological method is a good alternative because microbial activity involves the formation of much less bioavailable forms from toxic elements such as PTEs. In order to develop this method for the remediation large-scale contaminated soils, it is crucial to understand the mechanism used by microorganisms as well as the factors influencing these biogeochemical processes. Given the benefits of this method, researchers hope that by increasing its efficiency, bioremediation methods will replace other methods deidcated to soil contamination remediation. In this chapter, after presenting different methods and the importance of microorganisms in soil, we introduce the mechanism and factors influencing the bioremediation method. Environmental characteristics, target pollutants, and microorganisms interact with each other and affect the bioremediation process efficiency. In general, microorganisms reduce the risk of toxic pollutants dissemination in the environment by using various mechanisms, and in some mechanisms, they turn them into much less toxic chemical forms.