Potential of dandelion Taraxacum officinale/ as a bioindicator of manganese arising from the use of methylcyclopentadienyl manganese tricarbonyl in unleaded gasoline

Methylcyclopentadienyl manganese tricarbonyl MMT. is an organic manganese Mn. compound currently added to unleaded gasoline in Canada. It has been suggested that the combustion of MMT containing Mn could cause various deleterious health effects in animals and humans at very high concentrations. This study evaluates the potential of dandelions Taraxacum officinale. as bioindicators of Mn environmental comtamination. Samples were picked at three different distances from a highway: a highly exposed site Eqq., a lightly exposed site Eq. and a control site E., located respectively at 10, 50 and 100 m. The total Mn, Mg, Ca, Al, Fe and Zn concentrations were measured in the soils and in the plants flower, stem, leaves and root. by neutron activation analysis. Exchangeable Mn was measured in soils by atomic absorption spectrophotometry. Mn concentrations of the different parts of the plant and exchangeable Mn in soils were not correlated with distance from the roadway and, thus, do not seem to be a sensitive indicator of Mn contamination. Soil Mn concentrations were correlated with distance from the roadway. This suggests the hypothesis that the environmental fate of Mn from MMT sources could be associated with an increased total Mn in soil but does not lead to an increase in exchangeable Mn.