Relevance of multi-component NAPL dissolution to source zone longevity

摘要

Lab column experiments have been used to determine processes controlling multi-component NAPL (non-aqueous phase liquid) dissolution, in particular the re-equilibration of aqueous dissolved-phase and Raoult's Law (solubility analogue) applicability. Bi-component mixtures of dichloromethane (DCM) and trichloroethene (TCE) have been studied in a multi-port column that samples the aqueous phase present along the NAPL length. Results to date suggest that Raoult's Law provides a reasonable, but not perfect description of behaviour. Re-equilibration of aqueous and NAPL of varying composition, that evolves even within an initially homogeneous multi-component NAPL, occurs over short length and time scales with the result that high-solubility components in the NAPL will be preferentially dissolved from the whole length of NAPL. The relevance of this research and recent field research by the authors to the longevity of multi-component NAPL source zones is summarized.