Influence of microbial activity on polar xenobiotic degradation in activated sludge systems.

The influence of activated sludge quality on the co-metabolic biodegradation of three aminocarboxylic [corrected] acids was investigated for a variety of Luxembourg sewage treatment plants. A combination of biodegradation experiments and respirometric techniques are presented as a reliable approach for the estimation of biokinetics and biological xenobiotic degradation rates that allow for identification of governing parameters such as microbial activity and active biomass. Results showed that biokinetics and degradation rates vary greatly between different plants.

A new concept linking observable stable isotope fractionation to transformation pathways of organic pollutants.

Measuring stable isotope fractionation of carbon, hydrogen, and other elements by Compound Specific Isotope Analysis (CSIA) is a new, innovative approach to assess organic pollutant degradation in the environment. Central to this concept is the Rayleigh equation which relates degradation-induced decreases in concentrations directly to concomitant changes in bulk (= average over the whole compound) isotope ratios. The extent of in situ transformation may therefore be inferred from measured isotope ratios in field samples, provided that an appropriate enrichment factor (epsilonbulk) is known.

Carbon isotope fractionation in the reductive dehalogenation of carbon tetrachloride at iron (hydr)oxide and iron sulfide minerals.

Compound-specific isotope analysis (CSIA) is used increasingly in contaminant hydrology in the attempt to assess the nature as well as the extent of in situ transformation reactions. Potentially, variations of stable isotope ratios along a contaminant plume may be used to quantify in situ degradation. In the present study, the abiotic dehalogenation of CCl4 by Fe(II) present at the surface of different iron minerals has been characterized in terms of the reaction rates and carbon isotopic fractionation (delta13C) of carbon tetrachloride (CCl4) as well as the yields and isotopic signatures of chloroform (CHCl3), one of the main transformation products.

New evaluation scheme for two-dimensional isotope analysis to decipher biodegradation processes: application to groundwater contamination by MTBE.

Compound-specific analysis of stable carbon and hydrogen isotopes was used to assess the fate of the gasoline additive methyl tert-butyl ether (MTBE) and its major degradation product tert-butyl alcohol (TBA) in a groundwater plume at an industrial disposal site. We present a novel approach to evaluate two-dimensional compound-specific isotope data with the potential to identify reaction mechanisms and to quantify the extent of biodegradation at complex field sites. Due to the widespread contaminant plume, multiple MTBE sources, the presence of numerous other organic pollutants, and the complex biogeochemical and hydrological regime atthe site, a traditional mass balance approach was not applicable.

[What influence doe the implant have on the perioperative morbidity following internal fixation of proximal femur fracture? Analysis of dynamic hip screw and proximal femoral nailing].

Rationale: Proximal femur fracture is a frequent finding in elderly patients. Both the dynamic hip screw (DHS) and the proximal femur nail (PFN) are established implants. The aim of our study was to assess the perioperative morbidity in a sample of 112 patients with proximal femur fracture, operated on with either DHS or PFN.