Remediation of organic pollutants by Brassica species

Abstract

Abstract The industrial revolution has put the soil environment under pollution, pouring a variety of toxic substances into it. These polluting substances include organic and inorganic compounds that pose health risks to human beings via food chain. At present, emphasis has been given to those organic pollutants that sometimes have persistence and reside in soil for a very long time. Major sources of organic pollutants are the agricultural inputs, industrial effluents, fossil fuel burning, and sewage wastes. Several classes of harmful organic pollutants include persistent organic pollutants (POPs), phenols, hexachlorocyclohexanes (HCHs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and dichlorodiphenyltrichloroethanes (DDTs). Ultimate sink of all these contaminants is water bodies and soil on which growing plants take up a significant portion of these contaminants, but their intratissue fate varies among species. Phytoremediation of the soils contaminated with these organic pollutants is an economical, environment friendly, and efficient technique. Brassica species being famous for their vigorous growth and hyperaccumulator nature have become a subject of extensive investigations regarding their role in accumulation and degradation of pollutants from soil and water bodies. Brassica species can maintain a good and healthy growth that makes tissue dilution of uptaken contaminants and degradation of these intracellular invasive species via modulating cellular physiology and enzymatic machinery. Brassica vigorous roots provide active sites for static adsorption of contaminants from soil and water bodies and release exudates that facilitate growth of contaminant-degrading rhizobacteria. Bacterial brassica partnership has an incremental impact on degradation of organic pollutants so does application of immobilizing organic and inorganic amendments. Once uptaken, these contaminants are converted into sulfur-containing compounds inside Brassica body that make dry tissue of Brassica species an excellent fuel leading their use for energy generation under biofumigation process. This chapter is an effort to give a comprehensive review on the fate of organic pollutants in the environment and the role of Brassica species in environmental cleansing via phytoremediation.