Sorption mechanism of organic compounds in karst: SOM or HSACM dependent?

摘要

Modelling the fate and transport of contaminants in groundwater requires an in-depth understanding of sorption processes in aquifer material. Sorption isotherms for chlorinated solvents and aromatic organic compounds have been developed for sands and clays. However, limited information exists regarding these compounds in limestone and other karst rock types. Research has shown that the sorption of organic contaminants is principally influenced by the presence of soil organic matter. High-surface area carbonaceous material (HSACM) has also been found to significantly affect sorption of contaminants. Limestone samples from various origins were characterized in terms of specific surface area, clay mineral, organic matter nature and content. Batch sorption experiments were carried out and isotherms were developed over a concentration range of 0.001% to 1% aqueous solubility of chloroform and dichloromethane. Analysis showed the fraction of organic carbon in these samples is less than 0.1%. However sorption was found to be greater than theoretically calculated.