Аннотация:Most aquifer materials are heterogeneous in terms of grain size distribution and petrography. To understand sorption kinetics, homogeneous subfractions, either separated from heterogeneous sands and gravels (lithocomponents) or fragments of fresh rocks, have to be studied. In this paper we present data on long-term sorption kinetics of phenanthrene for homogeneous samples consisting of one type of lithocomponents or fresh rock fragments in different grain sizes. Diffusion rate constants were determined in batch experiments using a numerical model for retarded intraparticle pore diffusion and correlated to grain size and intraparticle porosity of the lithocomponents. Sorption isotherms were nonlinear for all samples investigated (Kleineidam et al. (1)). The numerical model described the sorption kinetics very well for coarse sand and gravels. Tortuosity factors, which were obtained as final fitting factors, agreed with Archie's law predictions based on the intraparticle porosity. The dependency of sorptive uptake on grain size revealed that for smaller grains intrasorbent diffusion may become significant. This is attributed to relatively large particulate organic matter (POM) within the sedimentary rock fragments. Specifically, charcoal and coal particles, which were found in some of the sandstones, controlled the sorptive uptake rates.
Ключевые слова:Groundwater flow and contamination studies, Radioactive element chemistry and processing, Hydrocarbon exploration and reservoir analysis
