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Title: Phytoremediation of Soil Trace Elements

item Chaney, Rufus

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/8/2009
Publication Date: 4/16/2010
Citation: Chaney, R.L. 2010. Phytoremediation of Soil Trace Elements. Meeting Abstract.

Interpretive Summary: .

Technical Abstract: Phytoremediation includes several distinct approaches to using plants to achieve soil remediation goals. Phytoextraction uses rare hyperaccumulator plants to accumulate in their shoots enough metals per year to achieve decontamination goals. Phytomining uses hyperaccumulators and biomass burn to produce high grade metal ores for sale. Phytovolatilization uses plants to produce volatile forms of Se or Hg which leave the soil. Phytostabilization uses combination of soil amendments and growing plants to alleviate toxicity risks to plants and animals from soil metals which are not effectively accumulated by plants, such as Pb. Planned land use controls remediation goals and the practicality of phytoextraction vs. phytostabilization vs. soil removal and replacement. Research has shown that very strongly Zn-Pb-Cd contaminated soils (mine wastes or smelter emissions) require remediation of Zn phytotoxicity which can be achieved by raising soil pH to make the soil calcareous in order to provide a persistent remediation; high phosphate or Fe oxides to increase sorption of Zn, Pb, Cd and As and formation of chloropyromorphite to reduce the bioavailability of Pb in ingested soils. With the normal Cd:Zn ratio of mining/smelting contaminated sites, Cd has not been found to comprise risk to humans, livestock or wildlife after Zn phytotoxicity has been alleviated. Evidence supporting effective in situ remediation using byproducts such as biosolids and limestone is quite strong and based on multi-year field demonstrations which confirmed protection of wildlife and soil organisms. Cd phytoextraction using Thlaspi caerulescens ecotypes from southern France offers an effective method to remove Cd from European soils, but until government or polluters require decontamination, no one has been able to breed improved cultivars which perform in the field. Development of phytoremediation technologies require funds to support the movement of technology from research and demonstration to effective field remediation. On the other hand, proper use of risk assessment shows that most Zn-Cd contaminated sites in the EU will not require Cd remediation, while rice soils in Asia require extensive Cd phytoextraction to produce safe food for subsistence farm families. Use of the whole range of agricultural technologies to support phytoremediation has shown the potential of this method to solve soil contamination problems.