Andreas P. Loibner

Toxicity testing of 16 priority polycyclic aromatic hydrocarbons using Lumistox.

Hazard assessment of industrial sites contaminated with coal tar and its products usually focuses on selected pollutants such as the 16 polycyclic aromatic hydrocarbons (PAHs) prioritized by the U.S. Environmental Protection Agency (U.S. EPA). The aim of this study was to investigate to which extent these 16 PAHs contribute to the Vibrio fischeri bioluminescence inhibition measured by the acute Lumistox luminescent bacteria test. Five of the 16 PAHs-naphthalene (NAP), acenaphthylene (ACY), acenaphthene (ACE), fluorene (FLU), and phenanthrene (PHE)-revealed inhibiting effects when measuring saturated aqueous solutions of these compounds. However, in elutriates of PAH-contaminated soils, the amount of leached PAHs was very low, and the 16 PAHs did not considerably contribute to the observed bioluminescence inhibition. Nevertheless, bioluminescence inhibition was higher for elutriates with increased PAH concentration indicating the presence of other toxicants that co-occur with the 16 PAHs. No evidence was observed for increased bioluminescence inhibition due to synergistic effects among PAHs as calculated on the basis of toxic units for an aqueous solution containing all 16 priority PAHs. Data suggest that the U.S. EPA PAHs play only a minor role in causing acute toxicity to V. fischeri when exposed to aqueous elutriates of PAH-contaminated soils.

Changes in iso- and n-alkane distribution during biodegradation of crude oil under nitrate and sulphate reducing conditions

Crude oil consists of a large number of hydrocarbons with different susceptibility to microbial degradation. The influence of hydrocarbon structure and molecular weight on hydrocarbon biodegradation under anaerobic conditions is not fully explored. In this study oxygen, nitrate and sulphate served as terminal electron acceptors (TEAs) for the microbial degradation of a paraffin-rich crude oil in a freshly contaminated soil. During 185 days of incubation, alkanes from n-C11 to n-C39, three n- to iso-alkane ratios commonly used as weathering indicators and the unresolved complex mixture (UCM) were quantified and statistically analyzed. The use of different TEAs for hydrocarbon degradation resulted in dissimilar degradative patterns for n- and iso-alkanes. While n-alkane biodegradation followed well-established patterns under aerobic conditions, lower molecular weight alkanes were found to be more recalcitrant than mid- to high-molecular weight alkanes under nitrate-reducing conditions. Biodegradation with sulphate as the TEA was most pronounced for long-chain (n-C32 to n-C39) alkanes. The observation of increasing ratios of n-C17 to pristane and of n-C18 to phytane provides first evidence of the preferential degradation of branched over normal alkanes under sulphate reducing conditions. The formation of distinctly different n- and iso-alkane biodegradation fingerprints under different electron accepting conditions may be used to assess the occurrence of specific degradation processes at a contaminated site. The use of n- to iso-alkane ratios for this purpose may require adjustment if applied for anaerobic sites.

Environmental Toxicity Testing

1. Historical perspective and overview. Jim Wharfe, Science Group, Environment Agency, Wallingford, Oxfordshire, UK. 2. Effective monitoring of the environment for toxicity. Ian Johnson and Paul Whitehouse, Water Research Centre, Marlow, Buckinghamshire, UK, and Mark Crane, Crane Consultants, Faringdon, Oxfordshire, UK. 3. The nature and chemistry of toxicants. Ulf Lidman, Department of Biology, University of Kalmar, Sweden. 4. Frameworks for the application of toxicity data. Maria Consuelo Diaz--Baez and Bernard J. Dutka, Universidad Nacional de Colombia, Facultad de Ingenieria Ambiental, Bogota, Colombia. 5. The aquatic environment. William L. Goodfellow Jnr, EA Engineering Science and Technology, Sparks, Maryland, USA. 6. Biological methods for assessing potentially contaminated soils. David J. Spurgeon, Claus Svendsen and Peter K. Hankard, Centre for Ecology & Hydrology, Huntingdon, Cambridgeshire, UK. 7. Review of biomarkers and new techniques for in situ aquatic studies with bivalves. Francois Gagne and Christian Blaise, Environment Canada, Montreal, Canada. 8. Environmental monitoring for genotoxic compounds. Johan Bierkens, Ethel Brits and Luc Verschaeve, VITO Flemish Institute for Technological Research, Mol, Belgium. 9. Approach to legislation in a global context:. A -- UK perspective. Jim Wharfe, National Centre for Ecotoxicology and Hazardous Substances, Environment Agency, Wallingford, Oxfordshire, UK. B -- Netherlands perspective -- Soils and Sediments. Michiel Rutgers, National Institute for Public Health and the Environment, Bilthoven, The Netherlands and Piet den Besten, Institute for Inland Water Management and Waste Water Treatment (RIZA), Ministry of Transport, Lelystad, The Netherlands. C -- German perspective. Hans--Jurgen Pluta and Monika Rosenberg, Umweltbundesamt, Berlin, Germany. D -- USA perspective. Barbara Brown and Margarete Heber, US Environmental Protection Agency, Washington DC, USA. 10. Case study: whole effluent assessment using a combined biodegradation and toxicity approach. Graham F. Whale and Nigel S. Battersby, Shell R & T Centre, Chester, UK. 11. Potential future developments in ecotoxicology. Wim De Coen, Geert Huyskens, Roel Smolders, Freddy Dardenne, Johan Robbens, Marleen Maras and Ronny Blust, Laboratory for Ecophysiology, Biochemistry and Toxicology, University of Antwerp, Belgium. References. Index...

Investigation of different yeast strains for the detoxification of ochratoxin A

High concentrations of ochratoxin A (OTA) in feed lead to growth depression in animals. It has been reported that binders can be used for deactivating aflatoxins but not for other mycotoxins without negatively influencing the animals health. In this study a strain from the genus ofTrichosporon with the ability to cleave ochratoxin A very selectively into phenylalanine and the non-toxic ochratoxin α (OTα) could be isolated. This strain was selected from a pool of OTA detoxifying microorganism by carrying out several investigations.Trichosporon sp. nov. can be fermented and stabilized. In a feeding trial with broilers lyophilizedTrichosporon-cells could compensate performance losses caused by OTA.

Behavior of PAHs during cold storage of historically contaminated soil samples

The stability of historically polycyclic aromatic hydrocarbon (PAH)-contaminated soils during cold storage was investigated. Samples from two former manufactured gas plants exhibited quantitative recoveries of PAHs over the whole period of sample holding at 4 degrees C in the dark (8-10 months), whereas significant losses of PAHs were observed for soils received from a former railroad sleeper preservation plant with low molecular weight compounds being notably more affected compared to heavier PAHs. Already after 2 weeks of holding time, 3-ring PAHs in one of theses samples were down to 29-73% of the initial concentration and significant losses were observed for up to 5-ring compounds. Dissipation of PAHs was found to be predominantly due to aerobic microbial metabolism since sodium azide poisoned samples showed quantitative recoveries for all PAHs over the entire storage time of 3 months. A similar stabilizing effect was observed for freezing at -20 degrees C as means of preservation. Except for acenaphthene, no significant loss for any of the PAHs was observed over 6 weeks of holding time. Eventually, selected chemical, physical, and biological parameters of two soils were investigated and identified as potential indicators for the stability of PAH-contaminated soil samples.

Changes in bacterial communities from anaerobic digesters during petroleum hydrocarbon degradation

Anaerobic biodegradation of petroleum hydrocarbons (PHC) to methane has been recognized to occur in oil reservoirs and contaminated surface sites alike. This process could be employed efficiently for the treatment of contaminated materials, including petrochemical wastes and PHC-contaminated soil, since no external electron acceptor is required. Moreover, the controlled production of methane in digestion plants, similarly to the anaerobic digestion (AD) of energy crops or organic residues, would enable for energy recovery from these wastes. At present, little is known about the bacterial communities involved in and responsible for hydrocarbon fermentation, the initial step in PHC conversion to methane. In the present study, the fate of two different methanogenic communities derived from the AD of wastewater (WWT) and of biowaste, mixed with PHC-contaminated soil (SWT), was monitored during incubation with PHC using denaturing gradient gel electrophoresis (DGGE) of 16S rDNA genes amplified with Bacteria-specific primers. During 11 months of incubation, slight but significant degradation of PHC occurred in both sludges and distinct bacterial communities were developing. In both sludges, Bacteroidetes were found. In addition, in WWT, the bacterial community was found to be dominated by Synergistetes and Proteobacteria, while Firmicutes and unidentified members were abundant in SWT. These results indicate that bacterial communities from anaerobic digesters can adapt to and degrade petroleum hydrocarbons. The decontamination of PHC-containing waste via fermentative treatment appears possible.

Potential of preliminary test methods to predict biodegradation performance of petroleum hydrocarbons in soil.

Preliminary tests at different scales such as degradation experiments (laboratory) in shaking flasks, soil columns and lysimeters as well as in situ respiration tests (field) were performed with soil from two hydrocarbon contaminated sites. Tests have been evaluated in terms of their potential to provide information on feasibility, degradation rates and residual concentration of bioremediation in the vadose zone. Sample size, costs and duration increased with experimental scale in the order shaking flasks – soil columns – lysimeter – in situ respiration tests, only time demand of respiration tests was relatively low. First-order rate constants observed in degradation experiments exhibited significant differences between both, different experimental sizes and different soils. Rates were in line with type and history of contamination at the sites, but somewhat overestimated field rates particularly in small scale experiments. All laboratory experiments allowed an estimation of residual concentrations after remediation. In situ respiration tests were found to be an appropriate pre-testing and monitoring tool for bioventing although residual concentrations cannot be predicted from in situ respiration tests. Moreover, this method does not account for potential limitations that might hamper biodegradation in the longer term but only reflects the actual degradation potential when the test is performed.

Influence of the nature of soil organic matter on the sorption behaviour of pentadecane as determined by PLS analysis of mid-infrared DRIFT and solid-state 13C NMR spectra

The nature of soil organic matter (SOM) functional groups associated with sorption processes was determined by correlating partitioning coefficients with solid-state (13)C nuclear magnetic resonance (NMR) and diffuse reflectance mid-infrared (DRIFT) spectral features using partial least squares (PLS) regression analysis. Partitioning sorption coefficients for n-pentadecane (n-C(15)) were determined for three alternative models: the Langmuir model, the dual distributed reactive domain model (DRDM) and the Freundlich model, where the latter was found to be the most appropriate. NMR-derived constitutional descriptors did not correlate with Freundlich model parameters. By contrast, PLS analysis revealed the most likely nature of the functional groups in SOM associated with n-C(15) sorption coefficients (K(F)) to be aromatic, possibly porous soil char, rather than aliphatic organic components for the presently investigated soils. High PLS cross-validation correlation suggested that the model was robust for the purpose of characterising the functional group chemistry important for n-C(15) sorption.

Assessment of Factors Governing Biodegradability of PAHs in Three Soils Aged Under Field Conditions

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants of great environmental concern due to their toxic, mutagenic and carcinogenic properties. This study correlates soil characteristics (i.e. soil organic matter, particle- and pore-size distribution) with extractability and toxicity data (LUMIStox, Ostracod) to investigate factors that govern biodegradability of PAHs in three historically contaminated soils. Desorption of PAHs occurred most readily from soil TA1 (82%), followed by soil AS3.7 (69%) and soil WG2 (20%). This is in line with toxicity data, as the soil in which the greatest contaminant desorption (SFE) was observed exhibited the highest toxicity (TA1). Of the three soils, pronounced biodegradation of 2-4-ring, and slight biodegradation of 5-ring PAHs was observed only in AS3.7, while no decrease of PAHs was reported for soils WG2 and TA1 during the degradation experiment. Strong sorption reduced pollutant bioavailability in WG2 and hence hampered biodegradation. By contrast, pollutant sorption was weak in TA1 and microbial activity was most likely inhibited due to high toxicity in this soil. Based on our results we conclude that biodegradation of PAHs in soils is determined by a number of phenomena with complex interactions between them. Consideration of a single factor will be misleading and may result in false prediction of the biodegradation potential.

Identification and antimicrobial susceptibility of porcine bacteria that inhibit the growth of Brachyspira hyodysenteriae in vitro.

Aims:  To identify bacilli, lactic acid bacteria and bifidobacteria that inhibit the growth of Brachyspira hyodysenteriae.