Recent sediment deposition rates in the Oyster Ground, North Sea
Zuo, Z.; Eisma, D.; Berger, G.W. (1989). Recent sediment deposition rates in the Oyster Ground, North Sea. Neth. J. Sea Res. 23(3): 263-269
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, meer
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| Auteurs | | Top |
- Zuo, Z.
- Eisma, D., meer
- Berger, G.W.
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| Abstract |
Recent sediment accumulation rates were calculated from downcore 210Pb-excess activity profiles obtained from box cores taken in the Oyster Ground, North Sea. The rates ranged from 0.04 to 0.94 cm·yr-1 with an average of 0.39 cm·yr-1. In the top sediment layer the activities were rather low, the highest being only 1.15 dpm·g-1, and the average value 0.92 dpm·g-1. As shown by X-ray radiographs, downcore variations in texture were small: most samples being homogeneous and lacking primary sedimentary structures. Burrowing was evident in all cores, and most of them had a surface mixed layer of at least 5 cm, below which the 210Pb activity rapidly dropped to background value. Downcore deviations from the logarithmic decrease in 210Pb with depth could generally be attributed to biological disturbance or physical processes causing reworking of the sediment. Only in one core did the 210Pb activity decrease regularly with depth. The activities of 137Cs in this core and another demonstrated recent accumulation rates of 0.44 and 0.88 cm·yr-1, respectively, which are in good agreement with the rates obtained from the 210Pb method in the same cores (viz. 0.37 and 0.94 cm·yr-1). From these sedimentation rates the total amount of mud yearly deposited in the muddy part of the Oyster Ground is estimated to be in the order of 2x109 kg·yr-1, which is 4 to 5% of the total amount of mud yearly deposited in the North Sea. |
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