Modelling of geochemical and isotopic changes in a column experiment for degradation of TCE by zero-valent iron

Zero-valent iron (ZVI) permeable-reactive barriers have become an increasingly used remediation option for the in situ removal of various organic and inorganic chemicals from contaminated groundwater. In the present study a process-based numerical model for the transport and reactions of chlorinated hydrocarbon in the presence of ZVI has been developed and applied to analyse a comprehensive data set from laboratory-scale flow-through experiments. The model formulation includes a reaction network for the individual sequential and/or parallel transformation of chlorinated hydrocarbons by ZVI, for the resulting geochemical changes such as mineral precipitation, and for the carbon isotope fractionation that occurs during each of the transformation reactions of the organic compounds. The isotopic fractionation was modelled by formulating separate reaction networks for lighter ((12)C) and heavier ((13)C) isotopes. The simulation of a column experiment involving the parallel degradation of TCE by hydrogenolysis and beta-elimination can conclusively reproduce the observed concentration profiles of all collected organic and inorganic data as well as the observed carbon isotope ratios of TCE and its daughter products.     

Phthalates in house dust

The main objective of this study was to generate a fast analytical method to determine the five phthalates benzylbutylphthalate (BBP), dibutylphthalate (DBP), di-(2-ethylhexyl)-phthalate (DEHP), di-isodecylphthalate (DIDP), and di-isononylphthalate (DINP) in house dust. To achieve this liquid chromatography electrospray tandem mass spectrometry (LC–ESI–MS/MS) was used for measurement. The risk of lab- and cross-contamination was nearly eliminated completely as a very short and fast sample preparation including a sieving step and an ultrasonic extraction for the analytes from the dust samples was used. Quantification through internal standard calibration resulted in low limits of determination (DEHP 4 mg kg^? 1 to DBP 14 mg kg^? 1). A potential interaction between the analytes DIDP and DINP during chromatographic measurement could be excluded while performing a two level factorial design. Furthermore it was examined to what extend carpet and plastic materials respectively have influence on the total amount of phthalates in dust. It could be shown that apartments in which a minimum of both of these sources appeared revealed the lowest total amount of sum of phthalates in dust (median 362 mg kg^? 1).     

PCDD/F and dioxin-like PCB profiles in soils amended with sewage sludge,compost, farmyard manure,and mineral fertilizer since 1962

Background, aim, and scope  

Biowaste contains compounds of agricultural value such as organic carbon, nutrients, and trace elements and can partially replace mineral fertilizer (MIN) and improve the physical properties of the soil. However, the obvious benefits of land spreading need to be carefully evaluated against potential adverse effects on the environment and human health. Environmental contamination resulting from biowaste application is one of the key variables when assessing cost/benefits. This study provides data on the resulting concentration of polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in the soil column as a result of the different types of fertilizers.     

Editorial: über die Zukunft deutschsprachiger wissenschaftlicher Zeitschriften

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