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Title: REALISATION OF THE POTENTIAL FOR USING HYPERACCUMULATING MTP'S IN THE REMEDIATION OF CONTAMINATED LAND AT MINES AND ELSEWHERE

Author
item REEVES, ROGER - MASSEY UNIV, NZ
item BAKER, ALAN - UNIV OF MELBOURNE AUS
item ZHAO, FAN-JIE - ROTHAMSTED, UK
item CHANEY, RUFUS

Submitted to: International Mining and Minerals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: This paper summarizes the information and recommendations from a Workshop on Metal Tolerant Plants held at the Kew Botanic Gardens in 2001. The state of knowledge of metal-tolerant plants (MTPs) as they occur in nature, and the discovery of the behaviour of those species that act as hyperaccumulators are reviewed. Plant species highly resistant to soil metals have evolved at many locations where surface soils were rich in metals for long periods. Information on MTPs needs to be consolidated into databases, and a system developed to conserve hyperaccumulator MTPs through the establishment of seedbanks, living collections, and propagation programmes, and of researches needed to bring hyperaccumulating MTPs into cultivation, and to commercialise their application. MTPs can be used to revegetate metal rich soils and wastes; locally collected plants are likely to be adapted to all climatic conditions of a site, and may provide effective revegetation with simple improvement in soil fertility and pH adjustment. For hyperaccumulators, MTPs must be domesticated and all aspects of growing the crop established. Germplasm collections must be screened for yield and metal accumulation from soil. Methods to process the biomass and recover the metals for recycling need to be demonstrated if the biomass metals merit recycling rather than disposal. Most elements are not hyperaccumulated by any plant species, and application of chelating agents to promote metal uptake are prohibitively expensive and cause leaching of metals to groundwater. But for Zn, Cd, Ni, Co, As, and a few other elements, hyperaccumulators are available for possible development into commercial phytoextraction systems.

Technical Abstract: This paper considers our state of knowledge of metal-tolerant plants (MTPs) as they occur in nature, and the discovery of the behaviour of those species that act as hyperaccumulators. Plant species highly resistant to soil metals have evolved at many locations where surface soils were rich in metals for long periods. Many more Ni hyperaccumulators exist in nature than for other metals because of the much larger land area of serpentine soils than other metal rich soils. Information on MTPs needs to be consolidated, and a system developed to conserve hyperaccumulator MTPs through the establishment of seedbanks, living collections, and propagation programmes, and of researches needed to bring hyperaccumulating MTPs into cultivation, and to commercialise their application. MTPs can be used to revegetate metal rich soils and wastes; locally collected plants are likely to be adapted to all climatic conditions of a site, and may provide effective revegetation with simple improvement in soil fertility and pH adjustment. For hyperaccumulators, MTPs must be domesticated and all aspects of growing the crop established. Germplasm collections must be screened for properties with contribute to annual phytoextraction. And methods to process the biomass and recover the metals for recycling need to be demonstrated if the biomass metals merit recycling rather than disposal. For Ni and Co, it is likely that the hyperaccumulated metals have sufficient value to support phytomining for value rather than only soil remediation. Most elements are not hyperaccumulated by any plant species, and application of chelating agents to promote metal uptake are prohibitively expensive and cause leaching of metals to groundwater.