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Discussion |
1 Bradfield Hall, Cornell University, Ithaca, New York 14853, USA
2 Water UK, 1 Queen Anne’s Gate, London, SW1H 9BT, UK
3 Department of Civil & Environmental Engineering, Imperial College, London, SW7 2BU, UKt
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P. Baveye writes: In the title and abstract of their recent article, Tompkins et al. (2001) advocate engineered, in-situ bioremediation as a viable and practicable option for nitrate removal in Chalk aquifers. Surpringly, this enthusiastic endorsement appears to be severely undermined by the otherwise remarkably thorough and interesting multiscale analysis presented in the body of the article. Indeed, as a conclusion of this analysis, Tompkins et al. (2001, p. 121) point out that the ‘biochemical and hydrological flow processes controlling denitrification activity in fissured aquifers are complex and not yet sufficiently understood at this stage for the in-situ technology to be optimized and verified technically or economically’. They recommend that a systematic study be carried out, using a combined numerical and experimental approach, to develop a fundamental understanding of the mechanisms and factors controlling denitrification in Chalk.
Given the fact that the authors appear to be simultaneously on both side of the fence, it must be unclear to practitioners who would happen to read Tompkins et al.’s (2001) article whether they should feel encouraged to implement in-situ bioremediation strategies in Chalk aquifers, or whether for the time being they should turn to other options, until further experimental results and reliable models become available.
I would like to suggest that if the analysis of Tompkins et al. (2001) is taken one step further, a somewhat clearer picture emerges. The step in question consists of better taking into account the influence of microbial activity on the hydrodynamic characteristics of Chalk aquifers.
