The use of metal tolerant plant populations for the reclamation of metalliferous wastes.
Abstract
High concentrations of toxic metals appear to be the major cause of the sparse vegetation cover of metalliferous mine wastes in the UK, but comparisons of bare and adjacent vegetated areas suggest that phosphorus concentrations are the immediate determinant. Field experiments with a range of grass species at a large number of mine sites showed that naturally occurring tolerant populations grew faster and persisted longer than normal commercial varieties. They formed an excellent stabilizing cover, provided adequate fertilizer was applied, and have persisted for 9 years with little loss of vigour, even with minimal fertilizer treatment. The most successful populations at each site were those with the highest tolerance to the metals occurring in that waste, provided that the species was appropriately adapted to the other soil conditions occurring there. Three cultivars are now commercially available which are tolerant to: acid lead/zinc wastes (Agrostis tenuis, cv. Goginan), calcareous lead/zinc wastes (Festuca rubra, cv. Merlin) and copper wastes (Agrostis tenuis, cv. Parys). These permit stabilization of a wide variety of wastes.<new para>ADDITIONAL ABSTRACT:<new para>A survey was made of metalliferous mine wastes in UK. The results suggested that high conc. of toxic metals were the major cause of sparse vegetation cover, but comparisons of bare and adjacent vegetated areas suggested that P conc. were the immediate determinant. Field experiments using a range of grass spp. at a large number of mine sites showed that naturally occurring tolerant populations grew faster and persisted longer than normal commercial cv. They provided an excellent stabilizing cover provided adequate fertilizer was given, and persisted for 9 yr with little loss of vigour even with min. fertilizer treatment. The most successful populations at each site were those with the highest tolerance to the metals occurring in that waste, provided that the sp. was appropriately adapted to the other soil conditions occurring there. 3 cv. are now commercially available which are tolerant to: acid Pb/Zn wastes (Agrostis tenuis cv. Goginan), calcareous Pb/Zn wastes (Festuca rubra cv. Merlin) and Cu wastes (A. tenuis cv. Parys). These enable stabilization of a wide variety of wastes.