Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9451877 | Chemosphere | 2005 | 14 Pages |
Abstract
The aim of this study was to characterize the labile part of dissolved organic carbon (DOC) present in groundwater by identification of natural organic carbon substrates and to assess their microbial utilization during aeration of the groundwater. The studied chlorophenol (CP) contaminated groundwater contained 60-2650 μmol lâ1 of DOC of which up to 98.0% were CPs; 1.7% were low-molecular weight organic acids and 0.2% were dissolved free amino acids. Traces of following natural organic carbon substrates were identified: l-alanine, l-isoleucine, l-leucine, l-serine, l-threonine, l-tyrosine, l-valine, l-aspartic, acetic, citric, formic, lactic, malic and oxalic acid. Dissolved oxygen concentration inside the CP-plume was lower (mean 25 μmol lâ1) than outside of the plume (mean 102 μmol lâ1). Over a monitoring period of four years the concentrations of CPs, Fe(II) and NH4+ were higher inside than outside of the CP-plume. Oxygen availability within the CP-plume limits in situ biological oxidation of CPs, DOC, NH4+ and Fe(II). The microbial enzymatic hydrolysis rates of 4-methylumbelliferyl and 7-amino-4-methylcoumarin-linked substrates varied from 0.01 to 52 μmol lâ1 hâ1 and was slightly higher inside than outside the plume. Microbial uptake rates of 14C-acetate, 14C-glucose and 14C-leucine were on average 28, 4 and 4 pmol lâ1 hâ1 outside and 17, 25 and 8 pmol lâ1 hâ1 inside the plume, respectively. The indigenous microorganisms were shown able of hydrolysis of dissolved organic matter, uptake and utilization of natural organic carbon substrates. Therefore, the labile part of DOC serves as a pool of secondary substrates beside the CP-contaminants in the groundwater and possibly help in sustaining the growth of CP-degrading bacteria.
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Environmental Chemistry
Authors
J.H. Langwaldt, U. Münster, J.A. Puhakka,