Phytoremediation of heavy metals by Trifolium alexandrinum

Abstract

The release and persistence of toxic heavy metals into the natural environment is a serious concern especially in urban areas. The problem of heavy metal pollution is gaining momentum from year to year as more and more amounts of heavy metals are extracted from their ores and released into the environmental segments (water, air and soil) during processing or afterwards. Heavy metals are essentially nonbiodegradable and therefore accumulate in the environment and subsequently find their way into the food chains. Contamination of food chains by toxic heavy metals is an unwanted outcome of industrialization and unsustainable development. This contamination is a risk to the health of all organisms including humans. Entrance of toxic heavy metals (through absorption, inhalation and ingestion) into the human body beyond threshold limits causes many diseases and health abnormalities. Therefore, effective remediation of heavy metal pollution is a top priority. The different physico-chemical methods used for this purpose generally suffer from serious limitations. Phytoremediation is seen as an alternative green solution to the problem. The present study reports phytoremediation of Cd, Pb, Cu, and Zn by Trifolium alexandrinum, which is a suitable candidate plant species for this purpose. T. alexandrinum was grown in a simulated heavy metal-contaminated soil. Root bioconcentration factor values of T. alexandrinum for Zn, Pb, Cu and Cd were 4.242, 1.544, 1.071, and 0.604 respectively.