Sorption distribution coefficients: Discrepancy between batch and column techniques

Proper determination of sorption distribution coefficients of organic contaminants is essential for assessment of their transport in groundwater. This is usually determined from either a batch sorption isotherm or from a miscible displacement study through a soil column. Discrepancy between the results of the two techniques has been reported. The cause, however, is not clear and needs to be elucidated. In this paper, a all potential factors that cause discrepancy between the results of the two systems have been explored These factors are categorized into three groups: those related to fundamental differences between the two systems including levels of mixing, particle spacing, and soil-to-water ratio; those related to sorption nonideality including nonlinearity, nonsingularity, and nonequlibrium; and those related to experimental artifacts including loss of sorbent from soil columns, analytical difficulties, and unaccounted for transfer/transport mechanisms. Assessment of the impact of each factor on the extent of discrepancy is discussed.