Synergistic Effects of Organic and Metal Contaminants on Phytoremediation

Abstract

Numerous contaminated sites exist worldwide that contain a mixture of organic and heavy metal contaminants. Very few technologies are proven to be efficient to address the problem of such mixed contamination. Most of these technologies are energy-intensive and expensive and they can disturb the natural ecosystem. Phytoremediation has potential to be a green and sustainable approach to decontaminate and restore the contaminated sites, maintaining the biological activity and physical structure of the soils. However, its effectiveness for mixed contaminants is not well understood. This study presents series of laboratory experiments conducted to investigate the synergistic effects of organic and heavy metal contamination on phytoremediation. A silty clay (typical field soil) was spiked with: (1) naphthalene and phenanthrene (representative organic contaminants), (2) lead, cadmium, and chromium (representative heavy metals), or (3) combination of these organic and heavy metal contaminants. Different plant species, specifically Avena sativa (oat plant), Lolium perenne (perennial rye grass), Festuca arundinacea (tall fescue), and Helianthus annuus (sunflower), were grown in these contaminated soils as well as in uncontaminated soil for comparison purposes. Results showed that plants in the soil with organic contamination alone had growth characteristics similar to that in uncontaminated soil. However, the plants in the metal contaminated soil showed maximum distress. The plants in mixed contaminated soil performed better than those plants in soils with metal contaminants alone.