| Popis: |
The vertical distribution of organic C, sulphate-chlorinity ratio, sulphide concentration, oxygen consumption rate and ETS activity was studied over a column of 35 cm in sediments of a natural tidal flat and of a large artificial indoor tidal flat. Between the two sediments no principal differences were observed. The artificial one showed a little more organic carbon, higher sulphide concentrations and a higher oxygen consumption rate. The highest ETS activities were found at the surface of the artificial system. The distribution of the ETS activity in the sediment showed a rapid exponential decrease from the surface to 2 cm depth and a slow exponential decrease below that depth. At 1 cm depth the activity was more than halved and at 2 cm depth it was only 1 4 of the surface value. Notwithstanding this, over the column of 35 cm studied only 10% of the mineralization took place in the uppermost cm of the sediment, the rest was mineralized in the deeper anaerobic layers. From sulphate-chlorinity ratios it was concluded that in the anaerobic layer sulphate reduction occurs and that in the uppermost few mm of the sediment sulphate is produced by oxidation of reduced sulphur compounds moving up to this level. Comparing the ETS activity in the water column with the ETS activity in the sediment per m2 showed that the sediment plays by far the most important role in mineralization. |
