Biogeochemical studies on some nickel accumulating plants from New Zealand and New Caledonian serpentine areas : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University

Abstract

Serpentine areas in New Zealand and New Caledonia are described. A study was made of soil factors controlling the distribution of five species from a serpentine flora in the Dun Mountain area, South Island, New Zealand. Samples of soil were taken from sites of each of the species, and each sample was analysed for calcium, chromium, cobalt, copper, magnesium, manganese, nickel, potassium and zinc. On the basis of the species growing on them, the soil samples were divided into five groups: group 1, Pimelea suteri; group 2, Myosotis monroi; group 3, Lebe odora; group 4, Cassinia vauvilliersii; group 5, Leptospermum scoparium. Discriminant analysis was used to characterise each group of soils on the basis of chemical composition. The results showed that the two endemic plants (P. suteri and M. monroi) were much more commonly found in localities of highest magnesium concentration. These two species were strongly differentiated by the potassium and copper levels in their soils. No strong elemental discrimination was found among the non-endemic species. Correlation coefficients were calculated for the relationships between pairs of elements and highly-significant correlations (P 0.001) are reported. A nickel accumulating species from New Caledonia, Homalium kanaliense is compared with the New Zealand nickel accumulator, Pimelea suteri. The very high accumulation of nickel in the New Caledonian species, presents interesting questions in plant physiology. Purification of nickel complexes from an aqueous extract of B. kanaliense leaves was achieved and preliminary identification methods employed. None of the nickel was associated with amino acids and the present evidence suggested possible complexing of the nickel to simple carboxyllic sugars.