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The mesoscale sediment transport due to technical activities in the deep sea

J.A. Jankowski and W. Zielke

Abstract. This paper presents a mesoscale model for sediment transport in the deep sea resulting from technical activities such as manganese nodule mining. The model includes the temporal variability of ambient currents, the modification of the water density due to suspended sediments (density driven flow), bottom boundary-layer effects, and the influence of flocculation on the sediment settling velocity. It yields the three-dimensional sediment concentration and the bottom blanketing for time periods of up to a few weeks in areas of up to a few hundred square kilometers. The model also allows simulation of the mobilization, sorption and the transport of heavy metals. Two applications are presented. One treats the sediment transport during the NOAA Benthic Impact Experiment. The other is concerned with dispersion of heavy metals, including the interaction with suspended sediment in the Disturbance and Recolonization Experiment Experimental Area. The model is highly sophisticated with regard to the processes and numerical methods. Nevertheless, a final conclusion concerning the quantification of its prognostic capability for industrial scale operations cannot presently be drawn because of the lack of complete and coherent data sets.

The manuscript (not the paper) can be still obtained also from PDF file. Copyright 2001 Elsevier Science.

Reference: Jankowski, J.A. and Zielke, W. (2001) The mesoscale sediment transport due to technical activities in the deep sea. Deep-Sea Research Part II 48 p. 3487-3521. doi:10.1016/S0967-0645(01)00054-6

Parametrization and evaluation of marine environmental impacts produced by deep-sea manganese nodule mining

Oebius, H.U., Becker, H.J., Rolinski, S., Jankowski, J.A.

Abstract. The evaluation of marine environmental impacts resulting from the exploitation of marine resources requires the numerical description, parametrization, and modelling of such processes in order to be able to transfer, compare, and forecast the effects of anthropogenic activities in the deep sea. One of the controversial effects is the formation and behaviour of sediment clouds as a consequence of anthropogenic activities on the seafloor. Since there is a need for reliable data, two subprojects of the Interdisciplinary Deep-sea Environmental Protection Group (TUSCH) project Impacts from Technical Activities on the Deep-Sea Ecosystem of the South East Pacific Offshore Peru (ATESEPP) were devoted to the assembly of such data. Based on the German technical approach for deep-sea mining, the possible environmental impacts by a miner were estimated, the impacts on the seafloor were simulated and investigated by tests with large volume undisturbed sediment samples on board the research vessel and in the laboratory, and the results were evaluated and extrapolated. This report gives a comprehensive presentation of the physical problems, the technical approach, and the results of these investigations.

Reference: Oebius, H.U., Becker, H.J., Rolinski, S., Jankowski, J.A. (2001) Parametrization and evaluation of marine environmental impacts produced by deep-sea manganese nodule mining. Deep-Sea Research Part II 48 p. 3453-3467. doi:10.1016/S0967-0645(01)00052-2

© 2001 by jaj • mail:  jacek.jankowski@web.de