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Relation between bioavailability and fuel oil hydrocarbon composition in contaminated soils de Jonge, H.; Freijer, J.I.; Verstraten, J.M.; Westerveld, J.W.; van der Wielen, F.W.M. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Bioavailability of oil components in contaminated soils is an important regulating factor for biodegradation rates. Changes in the composition of mineral oil can provide information regarding the bioavailability restrictions in contaminated soils. The fate of oil components was studied in a lysimeter experiment and laboratory incubations. A shift in the n-alkane ratios in the range n-C16:n-C20 was observed around 4.0 g kg -1 , indicating that two different mechanisms control the bioavailability of the oil. At higher concentrations, the bioavailability was controlled by solubilization from a non-aqueous-phase liquid into the aqueous soil water phase. The ratios remained constant with decreasing oil concentration in this stage. Below 4.0 g kg -1 , desorption and diffusion became rate-limiting factors: a shift was observed in the n-alkane ratios, showing that biodegradation rates of n-alkanes increased with decreasing carbon number. The monitoring of n-alkane ratios can be used to improve the efficiency of bioremediation treatments. Download date: 10 May 2018 Relation between Bioavailability and Fuel Oil Hydrocarbon Composition in Contaminated Soils H . D E J O N G E , * J . I . F R E I J E R , J . M . V E R S T R A T E N , A N D J . W E S T E R V E L D IntroductionBioavailability is considered a priority research objective in the bioremediation field (1), as it is an important but yet poorly quantified regulatory factor for the biodegradation of oil and other organic compounds in contaminated soils (2-5). An important but complex question for optimization of bioremediation processes is: When is bioavailability limiting the actual biodegradation rate? Besides bioavailability, biodegradation rates depend on (i) the presence of microbiota with the metabolic capacity to degrade the components of interest (6, 7); (ii) the recalcitrance of the compounds in the oil mixture (6,(8)(9)(10)(11)(12); and (iii) growth and activity factors (temperature, nutrients, electron acceptors, pH) influencing the microbial population dynamics (10,(13)(14)(15)(16)(...

SummaryIn comprehensive two-dimensional gas chromatography (GC6GC), two capillary columns are connected in series through an interface known as a "thermal modulator". This device transforms effluent from the first capillary column into a series of sharp injection-like chemical pulses suitable for high-speed chromatography on the second column. Dramatic increases in the resolving power, sensitivity, and speed of the gas chromatograph result. This paper describes the development of a robust and reliable thermal modulator for GC6GC.

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Since bacteria degrading polycyclic aromatic hydrocarbon compounds (PAHs) in polluted soils are generally exposed to mixtures of PAHs, we examined the influence of simple PAH mixtures on the degradation activity of Sphingomonas sp. strain LB126. Fluorene serves as sole carbon and energy source for the strain LB126 and phenanthrene and fluoranthene are cometabolically degraded by this species. Chemostat cultures of the strain LB126 were used to study a potential inhibiting effect of phenanthrene and fluoranthene on the degradation of fluorene that was previously observed in batch cultures. We also looked at the effect of phenanthrene on the degradation of glucose in a chemostat culture to see if this effect was specific for the PAH-metabolic pathway or for the total metabolism of the strain. The co-substrates were supplied in a 5% to 30% fraction of fluorene. Phenanthrene and fluoranthene had no significant influence on growth. However, fluorene degradation was inhibited by both phenanthrene and fluoranthene. The effect of phenanthrene was about 10 times stronger than the effect of fluoranthene. Nevertheless, more than 95% removal of fluorene took place together with more than 95% removal of either phenanthrene or fluoranthene. The effect of phenanthrene on the strain LB126 could be ascribed to both toxicity and competitive inhibition, but the effect observed at steady state was due to competitive inhibition only. It appeared that the strain LB126 adapts to the toxicity of phenanthrene within five generations. The inhibitory effects observed previously in batch cultures of the strain LB126 should mainly be ascribed to the toxic effect of phenanthrene.