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Commercially available heat transfer fluids used in borehole heat exchangers were investigated for their composition, their biodegradability as well as their ecotoxicity. The main components of the fluids are organic compounds (often glycols) for freezing protection. Biodegradation of the fluids in laboratory studies caused high oxygen depletion as well as nitrate/iron(III) reduction under anaerobic conditions. Additives such as benzotriazoles for corrosion protection were persistent. Ecotoxicity data show that the commercially available fluids caused much higher ecotoxicity than their main organic constituents. Consequently, with regard to groundwater protection pure water as heat transfer medium is recommended. The second best choice is the usage of glycols without any additives. Effects on groundwater quality should be considered during ecological-economical cost-benefit-analyses of further geothermal energy strategies. The protection of groundwater as the most important drinking water resource must take priority over the energy gain from aquifers.

A method for the quantification of the sum of short chain chlorinated paraffins (SCCPs) by GC–ECNI-MS was developed. This method is suited to the special demands of environmental sediment analysis using an approach of sum determination by multiple regression quantification and is independent of the chlorine content as well as robust against changes in C-number distribution of the SCCPs to be analysed. The method is based on the integration of the signals for two selected m/z values (375 and 423) over the full retention range of the SCCPs. The calibration is performed using three synthetic mixtures representing the variety of SCCP-mixtures as found in environmental samples as well as in technical mixtures. Quantification is performed using a multiple linear regression calibration with two selected m/z value signals achieving an LOQ of 0.6 μg/g sediment. The proposed quantification procedure for sediments was verified by 16 independently prepared and differently composed SCCP-mixtures mimicking a variety of sediment samples quoted in literature. For the analysis of the sediment samples a two-step clean-up was applied comprising a column chromatographic clean-up and GPC. The method allows for a standardized analysis according to the European water framework directive, especially in the case of trend monitoring of sediments.

International audience; A first preliminary interlaboratory trial was planned to prepare ISO/DIS 12010: Water quality - determination of short chain polychlorinated alkanes (SCCP) in water - method using GC/MS and electron capture negative ionisation (ECNI). The task was to determine the sum of short chain polychlorinated n-alkanes with carbon chain lengths of C10-C13 and a chlorine content between 49 and 67% in water by GC-ECNI-MS and quantification by multiple linear regression described in ISO/DIS 12010 as the compulsory method. Distributed samples were obtained from a real water extract spiked with a target concentration of 0.4 micro g/mL sum of SCCP, i.e. the environmental quality target level according to the Water Framework Directive. The interlaboratory trial included the calibration, a column chromatographic clean up, a concentration step and an integration of chromatographic unresolved humps as well as the quantification with multiple linear regression. Reproducibility standard deviations between 21.5 and 22.9% were achieved by 17 participating laboratories from four countries. The method outlined no significant difference of the results between the standard solution and a real water matrix extract. On the basis of this succeeded preliminary interlaboratory trial the final interlaboratory trial for validation of ISO 12010 was prepared in autumn 2010.