Lead accumulation in Quercus nigra and Q-velutina near smelting facilitiesin Alabama, USA

Lead is very toxic and if ingested can cause severe health problems to both animals and humans. To determine if lead accumulation in trees could provi de a direct pathway to enter the food chain, oaks (Q. nigra or Q. velutina) growing near two lead smelting facilities in Alabama, U.S.A., were analyze d for lead in acorns, leaves and tree cores. A relatively pristine site was used as a control. Lead was not detected in acorns collected at any site, and was only found in tree cores from the sites near smelters. Significant increases in tree core lead from 1975-1995 were detected at the active smel ter site. Results were different from the inactive smelter site; lead incre ased in tree cores until the smelter ceased operation, then decreased after closing. Soil lead decreased linearly with distance from both smelters. In addition, a significant positive relationship was observed between leaf an d soil lead at the site with the active smelter, and may be the result of b oth translocation via tree roots, and foliar absorption of deposited lead i ons into the leaf structure.