RESPONSE OF BLUE SPRUCE (PICEA-PUNGENS) TO MANGANESE POLLUTION FROM MMT

The use of methylcyclopentadienyl manganese tricarbonyl (MMT) in unlea ded gasoline has become a source of manganese (Mn) contamination to wh ich urban ecosystems are exposed. The potential of coniferous trees as spatial and chronological indicators of Mn pollutation was investigat ed. Manganese concentrations in xylem from blue spruce (Picea pungens) growing near (high-exposure site) and far (low-exposure site) from a road were measured as a function of the year of wood formation. Exchan geable Mn content, which is the soil fraction most readily available f or uptake by trees, was also measured in the soils of both sectors. Th e results of the soil analysis show that exchangeable Mn concentration s are about 10 times higher in soils exposed to contamination (p < 0.0 005), in comparison with the concentrations found in soils weakly expo sed. However, the Mn concentrations in the trees near the road were no t significantly different from those in the reference trees (p > 0.05) . Therefore, it appears that blue spruce is not sensitive to soil Mn c ontamination arising from the use of MMT in gasoline.