Soil properties which affect the retention of Pb(Ⅱ) were investigated in the laboratory. It was determined, through selective removal, that organic matter and Fe-oxides are of lesser importance in influencing Pb retention than are soil clay minerals. The following trend : clays > organic matter > Fe-oxides represents the relative importance of each constituent in the adsorption of Pb by soils. The consistently greater Pb uptake by surface over subsurface samples was apparently due to differences in organic matter content, inasmuch as organic matter removal from both resulted in similar adsorption characteristics.
All five soils studied exhibited a pH-dependent trend of adsorption. The extent of Pb adsorption was least at low pH values(4∼5), was maximum in the neutral pH range, and leveled off or diminished under more alkaline conditions.
There was no strong correlation between Pb uptake and soil cation exchange capacity as routinely measured by the NH4OAc method. A knowledge of clay mineralogy in conjunction with soil pH is suggested as being the most reliable guide to predicting Pb retention by soils.

• 박상원(계명대학교 환경과학과) | Sang Won Park