Distribution and possible immobilization of lead in a forest soil (Luvisol) profile*
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Geochemical analyses using a sequential extraction method and lead adsorption studies were carried out in order to characterize the distribution and adsorption of lead on each genetic horizon of a Luvisol profile developed on a pelagic clayey aleurolite. Clay illuviation is the most important pedogenic process in the profile studied. Its clay mineralogy is characterized by chlorite/vermiculite species with increasing chlorite component downward. The amount of carbonate minerals strongly increases in the lower part of the profile resulting in an abrupt rise in soil pH within a small distance. The Pb content of the soil profile exceeds the natural geochemical background only in the Ao horizon, and its amount decreases with depth in the profile without correcting for differences in bulk density, suggesting the binding of Pb to soil organic matter. According to the sequential extraction analysis the organic matter and carbonate content of the soil have the most significant effect on lead distribution. This effect varies in the different soil horizons. Lead adsorption experiments were carried out on whole soil samples, soil clay fractions, as well as on their carbonate and organic matter free variant. The different soil horizons adsorb lead to different extents depending on their organic matter, clay mineral and carbonate content; and the mineralogical features of soil clays significantly affect their lead adsorption capacity. The clay fraction adsorbs 25 more lead than the whole soil, while in the calcareous subsoil a significant proportion of lead is precipitated due to the alkaline conditions. 10 and 5 of adsorbed Pb can be leached with distilled water in the organic matter and clay mineral dominated soil horizons, respectively. These results suggest that soil organic matter plays a decisive role in the adsorption of Pb, but the fixation by clay minerals is stronger.
Key wordsadsorption geochemistry lead Luvisol sequential extraction
organic matter free
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- Brümmer, GW 1986Heavy metal species, mobility and availability in soilsBernhard, MBrinckman, FESadler, PJ eds. The Importance of Chemical ‘Speciation’ in Environmental Processes.SpringerBerlin169192Google Scholar
- Echeverría, JC, Morera, MT, Mazkarián, C, Garrido, JJ 1998Competitive sorption of heavy metal by soilsIsotherms and fractional factorial experiments. Environ Pollut101275284Google Scholar
- Fujikawa, Y, Fukui, M, Kudo, A 2001Vertical distributions of trace metals in natural soil horizons from Japan. Part 2. Effects of organic components in soilWater, Air Soil Pollut131305328Google Scholar
- Gomes, PC, Fontes, MPF, da Costa, LM, S. Mendoca, E 1997Fractional extraction of heavy metals from red–yellow Latosol (in Portuguese)Rev Brasil de Cien Solo21543551Google Scholar
- Kabata-Pendias, A, Pendias, H 1992Trace Elements in Soils and PlantsCRC PressBoca RatonGoogle Scholar
- KöM-EüM-FVM-KHVM No. 10/2000, Governmental decree about ‘The threshold limits of heavy metals for soils in Hungary’ (in Hungarian), Magyar Küzlöny 53, 3156–3167.Google Scholar
- Sparks, DL 1995Environmental Soil ChemistryAcademic PressSan Diego128Google Scholar
- Tessier, A, Campbell, PGC, Bisson, M 1979Sequential extraction procedure for the speciation of particulate trace metalsAnal Chem51844851Google Scholar
- Wang, EX, Bormann, FH, Benoit, G 1995Evidence of complete retention of atmospheric lead in the soils of northern hardwood forest ecosystemsEnviron Sci Technol29735739Google Scholar