MANGANESE ACCUMULATION ALONG UTAH ROADWAYS - A POSSIBLE INDICATION OFMOTOR-VEHICLE EXHAUST POLLUTION

An organic manganese compound is currently added to gasoline to replac e tetraethyl lead as an antiknock fuel additive in the USA and Canada. Combustion exhaust gases contain manganese oxides. Manganese oxides a re known to cause various deleterious health effects in experimental a nimals and humans. A held survey of roadside soil and plants in centra l Utah revealed that soil manganese concentrations in high traffic are as were up to 100-fold higher than historic lead levels. Soil manganes e concentrations were highly correlated with distance from the roadway . Lead concentrations seem to have changed little from values reported twenty years ago but may have moved deeper into the soil profile. In addition, roadside aquatic plants were higher in leaf tissue manganese than herbs or grasses. Plant tissue manganese content was better corr elated with plant type, traffic volume and microhabitat than with dist ance from the roadway. Submerged and emergent aquatic plants were sens itive bioindicators of manganese contamination. Roadside snow melt and water samples were low in manganese and lead content. We conclude tha t roadside soil and plants were apparently contaminated by manganese o xides from Mn-containing motor vehicle exhaust. Manganese concentratio ns in soil and in some plant species along impacted roadsides often ex ceeded levels known to cause toxicity.