Phytoremediation of Hydrocarbon Xenobiotics, Uptake and Degradation

Introduction

Petrochemical anthropogenic contaminants in soil and water are a byproduct of industrialization. In the past, mechanical methods of remediation have been successfully used to clean contaminated soil and water. Phytoremediation is effective at removing contaminants from soil and water (Wallace). Its efficacy has been proven and the chemical and biological processes are now better understood. This paper is a summary of the biochemical processes occurring in soil and within macrophytes that take xenobiotics from contaminants to CO2 and H2O.

Macrophytes are simultaneously in contact with soil, water and air, the three main ecological niches. Phytoremediation relies on naturally occurring biochemical processes. Microbial degradation in the soil and mineral uptake and transpiration by macrophytes, removes contaminants from soil and water. The processes take place in two zones, the soil / rhizosphere, and above ground in the stems and leaves.

Digestion in the Rhizosphere

The rhizosphere consists of the soil, microbes living within it and the roots of macrophytes which loosen and thereby provide oxygen the region. Soil contains bacteria and fungi capable of metabolizing polycyclic aromatic hydrocarbons (PAH). PAHs are composed of two or more benzene rings and/or pentacyclic molecules arranged in various structural configurations. Their hydrophobic nature makes them highly insoluble in water and recalcitrant in the natural environment. Anthropogenic PAHs in the environment can be remediated in situ through bacterial and fungal metabolic functions.

There are three main pathways of PAH degradation by bacteria and fungi; bacterial degradation via dioxygenase, lignolytic (grow on wood and are dependent on lignin) fungal...

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