Fate of Several Typical Organic Pollutants in Soil and Impacts of Earthworms and Plants

Abstract

Soil contamination with micropollutants has raised concerns in recent years. Typical micropollutants include traditional organic pollutants, e.g., polycyclic aromatic hydrocarbons and pentachlorophenol (PCP), and emerging micropollutions, e.g., endocrine-disrupting chemicals such as nonylphenol and brominated flame retardant such as tetrabromobisphenol A (TBBPA). These organic contaminants may pose risk to soil animals and plants and even to human health.

The pollutants in soil may undergo mineralization, degradation, sorption, bound-residue formation, and transformation to various metabolites. These processes can accelerate the dissipation of pollutions in soils, but the metabolites may be more toxic to soil organism. In this chapter, we reviewed the environmental fate of the aforementioned micropollutants in different soils and different redox conditions in our laboratory with ¹⁴C tracer.

Soil animals and plants can accumulate organic pollutants from soils and affect the environmental fate of the pollutions. We found that earthworms play crucial roles in the biotransformation of organic contaminant pollutants in the soil. They increase sorption of pollutants to soil (especially on fresh cast) and degradation of various organic pollutants in soil but decrease mineralization of the pollutants and produce more metabolites. Both laboratory and field studies showed that degradation by plants and their associated microbes is efficient to remove variety organic pollutants from soil. Wetland plants can stimulate metabolism and dissipation of TBBPA in submerged soil, and willow plants increase the removal of PCP from soil. These studies show a better understanding of transportation and biotransformation of concerned micropollutions and their metabolites in different soil types and conditions.