title: Optimizing phytoremediation of heavy metal-contaminated soil by exploiting plants' stress adaptation.
abstract: Soil phytoextraction is based on the ability of plants to extract contaminants from the soil. For less bioavailable metals, such as Pb, a chelator is added to the soil to mobilize the metal. The effect can be significant and in certain species, heavy metal accumulation can rapidly increase 10-fold. Accumulation of high levels of toxic metals may result in irreversible damage to the plant. Monitoring and controlling the phytotoxicity caused by EDTA-induced metal accumulation is crucial to optimize the remedial process, i.e. to achieve maximum uptake. We describe an EDTA-application procedure that minimizes phytotoxicity by increasing plant tolerance and allows phytoextraction of elevated levels of Pb and Cd. Brassica juncea is tested in soil with typical Pb and Cd concentrations of 500 mg kg-1 and 15 mg kg-1, respectively. Instead of a single dose treatment, the chelator is applied in multiple doses, that is, in several small increments, thus providing time for plants to initiate their adaptation mechanisms and raise their damage threshold. In situ monitoring of plant stress conditions by chlorophyll fluorescence recording allows for the identification of the saturating heavy metal accumulation process and of simultaneous plant deterioration.
authors.affiliation: Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary. Barocsi@eik.bme.hu
authors.forename: Attila
authors.initials: A
authors.lastname: Barocsi
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Csintalan
authors.forename: Laszlo
authors.initials: L
authors.lastname: Kocsanyi
authors.forename: Slavik
authors.initials: S
authors.lastname: Dushenkov
authors.forename: J Michael
authors.initials: JM
authors.lastname: Kuperberg
authors.forename: Rafal
authors.initials: R
authors.lastname: Kucharski
authors.forename: Peter I
authors.initials: PI
authors.lastname: Richter
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology*; D001673:Biodegradation, Environmental / Q000187:drug effects; D015415:Biomarkers; D002104:Cadmium / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004780:Environment, Controlled; D007854:Lead / Q000378:metabolism; D019216:Metals, Heavy / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010944:Plants / Q000187:drug effects / Q000378:metabolism*; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead; D004492:Edetic Acid