Bioenhanced dissolution of dense non-aqueous phase of XXXX as affected by iron reducing conditions: Model systems and environmental samples.

@entity596 @entity4966 @entity8798 @entity7398 @entity61248 @entity56744 @entity4965 @entity5189 @entity1786
The anaerobic biotransformation of @entity4965 ( @entity4966 ) can be affected by competing electron acceptors such as @entity596 . This study assessed the role of @entity596 reduction on the bioenhanced dissolution of @entity4966 dense non-aqueous phase liquid (DNAPL). Columns were set up as 1-D diffusion cells consisting of a lower DNAPL layer, a layer with an aquifer substratum and an upper water layer that is regularly refreshed. The substrata used were either inert sand or sand coated with 2-line @entity61248 (HFO) or two environmental @entity596 containing samples. The columns were inoculated with @entity56744 and were repeatedly fed with @entity5189 . In none of the diffusion cells, @entity7398 or @entity1786 was detected while dissolved and extractable @entity8798 increased strongly during 60d of incubation. The cis-DCE concentration peaked at 4.0cm from the DNAPL (inert sand) while it was at 3.4cm (sand+HFO), 1.7cm and 2.5cm (environmental samples). The @entity4966 concentration gradients near the DNAPL indicate that the DNAPL dissolution rate was larger than that in an abiotic cell by factors 1.3 (inert sand), 1.0 (sand+HFO) and 2.2 (both environmental samples). This results show that high bioavailable @entity596 in HFO reduces the @entity4966 degradation by competitive @entity596 reduction, yielding lower bioenhanced dissolution. However, @entity596 reduction in environmental samples was not reducing @entity4966 degradation and the dissolution factor was even larger than that of inert sand. It is speculated that physical factors, e.g. micro-niches in the environmental samples protect microorganisms from toxic concentrations of @entity4966 .
