Defining the distribution coefficient of heavy metals introduced to soils
2003
Yuan, G.
The Langmuir equation has been widely used to describe the sorption of plant nutrients by soils. The maximum sorption capacity derived from the equation is indicative of the ability of soils to retain the nutrients. Problems may arise if the solute of interest is a contaminant rather than a nutrient. This is because at maximum sorption the contaminant concentration in the soil solution would greatly exceed the concentration that is relevant and appropriate to environmental protection. Here a concept of distribution coefficient is proposed to show the proportion of introduced heavy metals in the solid (sorbed) and solution phases in soils. This coefficient can be conveniently derived from the parameters of the Freundlich equation. It is a concentration-dependent indicator, affected by heavy metal species, organic matter content, cation exchange properties, and soil mineralogy. Potential applications of this distribution coefficient in non-agricultural land uses such as waste disposal are discussed.
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