Measure of microbial turnover of carbon in anoxic freshwater sediments: cautionary comments |
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Authors: | J.Gwynfryn Jones Bernard M. Simon |
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Affiliation: | Freshwater Biological Association, The Ferry House, Ambleside, Cumbria LA22 OLP England |
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Abstract: | Small sediment cores were used to determine the turnover of a range of carbon substrates, particularly volatile fatty acids, by bentic bacteria. Volatile fatty acids were determined using an HPLC sytem in cojunction with a conductivity detector. At the low eluent strength used 1 μM acetate was detected with ease. Small cores were used in an attempt to maintain the natural partial pressure of hydrogen, an important factor in the control of anerobic metabolism of fatty acids. Although this is preferable to the disturbance of the sediment which occurs if it is resuspended a a slurry, problems are encountered at low substrate concentrations. The time taken for the added substrate to equilibrate in both radial and vertical planes may result in turnover times which vary with the incubation time used. Reduction of the qunatity of added substrate and increased replication may improve the accuracy of the estimates obtained, but more serious consideration must be given to the availability of the substrates to the benthic bacteria. |
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Keywords: | Acetate determination Acetate metabolism Sediments Turnover |
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