Environmental exposure scenario for reagents used in in-vitro diagnostics.

In-vitro diagnostic assays involve various substances that may be released into the environment via a sewage treatment plant if the effluent from diagnostic instruments is discharged into the drains. Because the release of liquid waste into the public sewer system is regulated at national and/or local levels, a risk assessment per site should be performed to determine whether the release of the effluent from in-vitro diagnostic equipment is compliant with applicable regulations. To facilitate the assessment, we developed a screening tool to generate exposure scenarios for chemical substances used in in-vitro diagnostic assays.

Response of methanotrophic activity and community structure to temperature changes in a diffusive CH/O counter gradient in an unsaturated porous medium.

Microbial methane oxidation is a key process in the global methane cycle. In the context of global warming, it is important to understand the responses of the methane-oxidizing microbial community to temperature changes in terms of community structure and activity. We studied microbial methane oxidation in a laboratory-column system in which a diffusive CH(4)/O(2) counter gradient was maintained in an unsaturated porous medium at temperatures between 4 and 20 degrees C.

Methanotrophic activity in a diffusive methane/oxygen counter-gradient in an unsaturated porous medium.

Microbial methane (CH4) oxidation is a main control on emissions of this important greenhouse gas from ecosystems such as contaminated aquifers or wetlands under aerobic onditions. Due to a lack of suitable model systems, we designed a laboratory column to study this process in diffusional CH4/O2 counter-gradients in unsaturated porous media. Analysis and simulations of the steady-state CH4, CO2 and O2 gas profiles showed that in a 15-cm-deep active zone, CH4 oxidation followed first-order kinetics with respect to CH4 with a high apparent first-order rate constant of approximately 30 h(-1).

Further validation of the HPCD-technique for the evaluation of PAH microbial availability in soil.

There is currently considerable scientific interest in finding a chemical technique capable of predicting bioavailability; non-exhaustive extraction techniques (NEETs) offer such potential. Hydroxypropyl-beta-cyclodextrin (HPCD), a NEET, is further validated through the investigation of concentration ranges, differing soil types, and the presence of co-contaminants. This is the first study to demonstrate the utility of the HPCD-extraction technique to predict the microbial availability to phenanthrene across a wide concentration range and independent of soil-contaminant contact time (123 d).

New field method: gas push-pull test for the in-situ quantification of microbial activities in the vadose zone.

Quantitative information on microbial processes in the field is important. Here we propose a new field method, the "gas push-pull test" (GPPT) for the in-situ quantification of microbial activities in the vadose zone. To evaluate the new method, we studied microbial methane oxidation above an anaerobic, petroleum-contaminated aquifer.