title: Sequential sorption of lead and cadmium in three tropical soils.
abstract: It is important to examine mechanisms of Pb and Cd sorption in soils to understand their bioavailability. The ability of three tropical soils to retain Pb, Cd, and Ca was evaluated. The objectives of this study were to (1) determine the extent to which soil sorption sites are metal specific, (2) investigate the nature of reactions between metals and soil surfaces, and (3) identify how metals compete for sorption sites when they are introduced to soils sequentially or concurrently. Lead was shown to be much less exchangeable than Cd and inhibited Cd sorption. Cadmium had little effect on Pb sorption, though both Ca and Cd inhibited the adsorption of Pb at exchange sites. Lead appears to more readily undergo inner-sphere surface complexation with soil surface functional groups than either Cd or Ca. Thus, regardless of when Pb is introduced to a soil, it should be less labile than Cd.
authors: Earth and Soil Sciences Department, California Polytechnic State University, 1 Grand Avenue, San Luis Obispo, CA 93407, USA. cappel@calpoly.edu
authors: Chip
authors: C
authors: Appel
authors: Lena Q
authors: LQ
authors: Ma
authors: Roy D
authors: RD
authors: Rhue
authors: William
authors: W
authors: Reve
mesh_terms: D000327:Adsorption; D001682:Biological Availability; D002104:Cadmium / Q000737:chemistry*; D004784:Environmental Monitoring / Q000379:methods*; D007854:Lead / Q000737:chemistry*; D012987:Soil; D012989:Soil Pollutants / Q000737:chemistry*; D014329:Tropical Climate
chemical_list: D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D007854:Lead