Distribution of Pb, Cd and Ba in soils and plants of two contaminated sites

Evaluation of metal accumulation in soils and plants is of environmental im portance due to their health effects on humans and other biota. Soil materi al and plant tissue were collected along transects in two heavily contamina ted facilities, a Superfund site and a lead-acid battery dump, and analyzed for metal content. Soil lend (Pb), cadmium (Cd) and barium (Ba) concentrat ions for the Superfund site averaged 55,480, 8.5 and 132.3 mg/kg, respectiv ely. Soil Pb occurred primarily in the carbonate, sulfide/residual and orga nic chemical fractions (41.6, 28.6 and 16.7%, respectively). Soil Pb, Cd an d Ba concentrations for the dump site averaged 29,400, 3.9 and 1130 mg/kg, respectively. Soil Pb occurred mostly in the organic and carbonate fraction s as 48.5 and 42.5%, respectively. Pb uptake in the two sites ranged from n on-detectable (Agrostemma githago, Plantago rugelii, Alliaria officinalis s hoots), to 1800 mg/kg (Agrostemma githago root). Cd uptake was maximal in T araxacum officinale at 15.4 mg/kg (Superfund site). In the majority (greate r than or equal to 65%) of the plants studied, root Ph and Cd content was h igher than that for the shoots. Tissue Pb correlated slightly with exchange able and soluble soil Pb; however, tissue Cd was poorly correlated with soi l Cd species. None of the sampled plants accumulated measurable amounts of Ba. Those plants that removed most Pb and Cd were predominantly herbaceous species, some of which produce sufficient biomass to be practical for phyto remediation technologies. Growth chamber studies demonstrated the ability o f T. officinale and Ambrosia artemisiifolia to successfully remove soil Pb and Cd during repeated crop-pings. Tissue Pb was correlated with exchangeab le soil. Pb at r(2) = 0.68 in Ambrosia artemisiifolia. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.