AbstractsEngineering

Phytoextraction is a potential remediation technique for low to moderate levels of dichlorodiphenyltrichloroethane (DDT)-contaminated soil. Identification of new species as phytoextractors of DDT is a vital step in establishing phytoextraction as a commercially-viable and environmental-friendly remediation technique. Thirteen of native and naturalized weed species were investigated both in field and greenhouse studies using DDT-contaminated soil from Point Pelee National Park (PPNP), ON, Canada. A screening study established the extraction capabilities of nine wild growing species and determined that four of these Trifolium pratense, Symphyotrichum novae-angliae, Solanum ptycanthum Dun. Verbascum thapsus have a higher DDT extraction potential than the known DDT phytoextractor Cucurbita. pepo ssp. pepo cv. Howden assuming plants are grown at optimal densities. A subsequent field trial was conducted using three native weed species and C. pepo at PPNP in low (291 ng/g), moderate (5083 ng/g) and high (10192 ng/g) DDT-contaminated sites. This study determined that two native species i.e. Schizachyrium scoparium and Panicum virgatum had higher shoot DDT extractions than C. pepo at the high DDT-contaminated site. An interesting and unique finding was that, DDT uptake of C. pepo is concentration dependent with a maximum uptake observed at a threshold soil DDT ~5000 ng/g. In contrast, such threshold soil DDT concentration was absent for weed species where uptake increases linearly with increasing soil DDT concentration. A final greenhouse study using four perennial native and naturalized weed species in low (2300 ng/g) and high (17500 ng/g) DDT-contaminated soils collected from PPNP, further demonstrated that weed species are capable of significant DDT phytoextraction Trifolium pratense in both low and high DDT-contaminated soil regardless of growing conditions exceeded C. pepo extraction by considering optimum planting density. Hence, it can be summarized that native (or naturalized) weed species show significant potential/prospect as phytoextractors of DDT, especially at ecologically sensitive sites where it is important to minimize habitat disturbance. It is noted that this is the first comprehensive study of DDT phytoextraction using of native weed species. La phytoextraction est une technique pouvant remédier les sols contaminés avec des niveaux faibles à modérés de dichlorodiphenyltrichloroéthane (DDT). L’identification de nouvelles espèces ayant la capacité de phytoextraire le DDT est une étape essentielle dans l'établissement de la phytoextraction comme technique de remédiation commercialement viable et respectueuse de l'environnement. Treize espèces d’herbes indigènes et naturalisées ont été étudiées dans des essais in-situ et dans une serre avec des sols contaminés au DDT provenant du parc national de la Pointe-Pelée (PNPP), ON, Canada. Une évaluation préalable a permis de déterminer les capacités d'extraction de neuf espèces sauvages et a démontré que quatre de ces espèces, Trifolium pratense, Symphyotrichum…