Hysteresis in the sorption and desorption of hydorphobic organic contaminants by soils and sediments 1. A comparative analysis of experimental protocols

摘要

Sorption and desorption equlibria were measured for an organic contaminant probe, phenan- threne, and five EPA reference soils and sediments to evaluate the existence and extent of apparent isotherm hysteresis. Three different experimental protocols were tested to assess their relative potentials for introduction of artifact. The results reveal that: i)all systems studied exhibit apparent sorption-desorption hysteresis; ii)the three protocols tested yield significantly different degrees of apparent hysteresis; iii)principal sources of artifact are solute losses to reactor components and failure to achieve equilibrium sorption conditions; iv)isotherm nonlinearlity elevates the potential for introduction of artifacts in the quantification of desorption hysteresis; and v)little if any 'solids effect' was observed.