Tolerance of heavy metals and the reclamation of industrial waste.
The Zn and Cu tolerance of populations of Agrostis tenuis, A. stolonifera, Anthoxanthum odoratum, Festuca rubra and F. ovina was tested on root growth in solution culture and the results compared with growth on Cu or Zn slag tips in the Lower Swansea Valley. Populations from mine spoil sites were generally more tolerant of Cu or Zn than populations from the slag tips or from uncontaminated soil. The correlation between Zn tolerance index and growth on Zn slag was small, but was significant when 1 aberrant population was discarded; Cu tolerance was correlated with growth on untreated Cu slag. Responses to NPK and lime on the slag tips were not significantly different between populations. Treatment with domestic refuse or sewage sludge did give differences in population response but these were not correlated with Cu or Zn tolerance. Plant growth appeared to be limited by factors other than the toxicity of a single heavy metal. The drip culture apparatus used in testing for toxicity is described.-R.B.