Soil Micro-interfaces Control the Fate of Pollutants in Soil Environment

Abstract

Environmental soil micro-interfaces are the collection and continuum of surfaces of soil clay minerals, oxides, organic matters, plant roots and microbes. The soil colloidal interfaces could be simply described as a diffuse electrical double-layer structure on the interface of soil particles and solutions. These heterogeneous micro-interfaces can be divided into three types based on their surface structure characterizations: siloxane, hydrous oxide and organic matter surfaces. The transport, transformation and degradation of pollutants in the soil are dynamic processes, including a series of reactions of sorption/desorption, precipitation/dissolution, complexation/chelation, and oxidation/reduction. Rhizosphere interface is the most active area in soil-plant ecosystems with intensive interactions among soil particles, organic compounds, plant roots and microorganisms. It is the channel of pollutant transporting to plants and linking with food chain. Microbial interface plays important roles not only in sorption and redox reactions of heavy metals, but also degradation and transformation of organic pollutants. As a dynamic continuum, different soil heterogeneous micro-interfaces interact with each other and control the forms, bioavailability, toxicity, transformation (degradation) and transport of pollutants in soil-plant ecosystems. Therefore, they are of significance in soil pollution control and remediation.