Partition and Adsorption on Soil and Mobility of Organic Pollutants and Pesticides. In: Gerstl Z, Chen Y, Mingelgrin U, Yaron B, editors. Toxic Organic Chemicals in Porous Media. Berlin: Springer Berlin Heidelberg; 1989. pp. 163-75. [DOI: 10.1007/978-3-642-74468-6_7]

Evaluation of rhamnolipid addition on the natural attenuation of estuarine sediments contaminated with diesel oil

The aim of the present study was to assess the bioremediation of estuarine sediments contaminated with diesel oil. The following two experiments were performed: natural attenuation (NA) and stimulated natural attenuation (SNA), using rhamnolipid as biosurfactant. Sediment samples were accommodated into glass columns and then contaminated with diesel oil on the top. The column profiles were separated into surface, middle, and bottom for the analyses. The 16 polycyclic aromatic hydrocarbons (PAHs) prioritized by US Environmental Protection Agency (EPA) were monitored for 349 days. Those with three and four rings showed increasing concentrations through the operation period in the middle and bottom samples, particularly between days 111 and 338, and in the SNA experiment. Those with five and six rings were also detected in the deeper portions of the columns, suggesting the percolation of PAHs with a high molecular weight. Total organic carbon was reduced by 91 and 89 % in the NA and SNA samples, respectively, although no statistically significant differences (p > 0.05) were found between the two treatments. The analyses by denaturing gradient gel electrophoresis indicated a slight shift in the microbial community structure over the experiments. Microorganisms belonging to the γ-Proteobacteria phylum were the main bacteria involved. The archaeal community exhibited dominance of hydrogenotrophic methanogens, indicating the obligate anaerobic biodegradation of intermediate compounds from hydrocarbon degradation.

Modeling sorption and biodegradation of phenanthrene in mangrove sediment slurry

A mathematical model, combining both sorption and biodegradation process, was developed to predict the biodegradation of phenanthrene by Sphingomonas sp. in different sediment slurries. The model includes two sorption parameters, α (the partition coefficient) and 1/K (the diffusion resistance); a kinetic parameter k (the first order rate constant); and a sediment parameter, A(V) (the specific sediment surface area in unit volume of slurry). These parameters were evaluated and verified in three types of sediment slurry systems (namely sandy clay loam Ho Chung sediment with fastest degradation, sandy Kei Ling Ha sediment with medium degradation, and clay Mai Po sediment with slowest degradation) at different initial phenanthrene concentrations. High R(2) values, ranging from 0.935 to 0.969, were obtained. Based on this integrated sorption-biodegradation model, the phenanthrene biodegradation in any sediment slurry could be predicted as long as the parameters of the specific sediment surface area in unit volume of slurry, total organic carbon and clay content were measured.

Sorption of selected polycyclic aromatic hydrocarbons on soils in oil-contaminated systems

The adsorption and desorption behaviour of selected polycyclic aromatic hydrocarbons (PAHs) on different soils was investigated by static and dynamic methods. On the basis of a system including the four phases of soil, water, oil adsorbed and oil in emulsion, a model for the description of the adsorption behaviour in the presence of oil was developed. In systems without oil a similar partitioning behaviour in the batch and column experiments was observed for all PAHs. Thus the distribution coefficients can be calculated from the octanol/water coefficient of the aromatic compounds and the organic carbon content of the soils. The presence of a lipophilic phase had a significant influence on the sorption of the PAHs, usually resulting in a drastic decrease of adsorption with increasing oil content in the system. For the oil-contaminated system the modelling of the adsorption behaviour enabled a more detailed interpretation of the experimental observations as well as the calculation of the sorption behaviour for the PAHs from characteristic parameters of the components involved.