Inactivation of mercury in contaminated soils using natural zeolites

The application of zeoliferous rocks, from Metaxades region (Thrace, Greece) to soils contaminated with mercury significantly reduced the concentrations of mercury in the shoots and roots of alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne). Use of natural zeolites at application rates of 1%, 2% and 5% by soil weight caused reductions in mercury concentrations of up to 86.0% in shoots and 58.2% in roots, compared with controls with no added zeolites. The reductions are more pronounced in above-ground plant material than in roots of the two plant species. The use of natural zeolites, as soil additives, to reduce the uptake of mercury by plants and the restriction of the entry of mercury into the food chain, is noted. (C) 1997 Elsevier Science B.V.