Role of Sulfate Reduction Versus Methanogenesis in Terminal Carbon Flow in Polluted Intertidal Sediment of Waimea Inlet, Nelson, New Zealand |
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| Authors: | Douglas O. Mountfort and Rodney A. Asher |
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| Abstract: | An investigation of the terminal anaerobic processes occurring in polluted intertidal sediments indicated that terminal carbon flow was mainly mediated by sulfate-reducing organisms in sediments with high sulfate concentrations (>10 mM in the interstitial water) exposed to low loadings of nutrient (equivalent to <102 kg of N · day−1) and biochemical oxygen demand (<0.7 × 103 kg · day−1) in effluents from different pollution sources. However, in sediments exposed to high loadings of nutrient (>102 kg of N · day−1) and biochemical oxygen demand (>0.7 × 103 kg · day−1), methanogenesis was the major process in the mediation of terminal carbon flow, and sulfate concentrations were low (≤2 mM). The respiratory index [14CO2/(14CO2 + 14CH4)] for [2-14C]acetate catabolism, a measure of terminal carbon flow, was ≥0.96 for sediment with high sulfate, but in sediments with sulfate as little as 10 μM in the interstitial water, respiratory index values of ≤0.22 were obtained. In the latter sediment, methane production rates as high as 3 μmol · g−1 (dry weight) · h−1 were obtained, and there was a potential for active sulfate reduction. |
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