Impact Of The Tsumeb Smelter Waste On Plant Species Diversity And Structure In Tsumeb, North-Central Namibia.

ABSTRACT

The objective of this study was to determine the impact of the smelter waste on plant species diversity and structure in the Tsumeb area. The most important sources of contamination are solid and gaseous emissions from the Tsumeb Smelter, airborne particles from the Tsumeb tailings pond and airborne particles from slag mill waste. Six sites: Inside Smelter Site, Outside Smelter Site, Abattoir Hill Site, Transnamib Site, Nomtsoub Site and Airport Site were selected and ten 10 m x 10 m plots were randomly demarcated at each site for soil and plant sampling. All 10 m x 10 m plots were used for sampling trees, nested within them were 5 m x 5 m and 2 m x 2 m plots which were used for sampling shrubs and grasses respectively. Top soils were sampled and analysed for concentration of arsenic, cadmium and lead. All trees (basal circumference >15 cm) as well as selected trees species, Combretum apiculatum and Terminalia prunioides were identified, counted and their heights as well as basal circumferences were measured. All shrubs, saplings and seedlings as well as a selected shrub, Dichrostachys cinerea, were identified, counted and their heights were measured. Grasses were identified and total grass cover was visually determined. Plant species diversity, richness, composition, woody cover and plant densities were determined. The results indicated high concentrations of arsenic, cadmium and lead at sites closer to the smelter. There were significant differences in plant species diversity (F=8.227, df=59, p