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Sediment Dynamics and Morphodynamics of River-Sea Sediment Dispersal Systems through Space and Time: A Source-to-Sink Perspective
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Dynamics of settling particles revealed by a non-sequential sediment trap mooring
Tuesday 8th @ 1530-1550, Conference Room 1
James T. Liu* , Department of Oceanography, National Sun Yat-sen University
Rick J. Yang, Department of Oceanography, National Sun Yat-sen University
Anchun Li, Institute of Oceanography, Chinese Academy of Science
Steven C. Chien, Department of Oceanography, National Sun Yat-sen University
Xiaoqin Du, School of Ocean Science and Technology, Zhejiang Ocean University
Chih-Chien Su, 4Institute of Oceanography, National Taiwan University
Yu-Shin Lin, Department of Oceanography, National Sun Yat-sen University
Presenter Email: james@mail.nsysu.edu.tw |
| An instrumented mooring was deployed off the mouth of Oujiang River in water depth of 25 m from Feb. 18 to March 18, 2014 over two spring-neap tidal cycles. It was configured with an SCTD, a downward-looking ADCP, and a non-sequential sediment trap whose opening was about 7 m above the seabed. Upon retrieval, the sediment trap had captured about 15-cm thick sediment. After returning to the lab, the trap sediment was first scanned through Multi-sensor Core Logger for physical attributes such as gamma-density, fractional porosity, and mass magnetic susceptibility. Samples were then extruded from the trap liner as 1-cm slices for the following analyses: grain size distribution, total 210Pb, TOC, TN, δ13C13, mineral content including mica or illite, kaolinite, chlorite, quartz, k-feldspar, plagioclase, and calcite. Examination of the down-trap variability of these sediment variables showed two general patterns: a secular trend and cyclical trend. The down-trap correlation (standardized co-variability) of the measured trap variables was analyzed using a multivariate technique EOF. The results show that the fist three modes explain 73.5% of the correlation. Mode 1 explains 43.4% of the data revealing the hydraulic sorting effect on the settling sediment, which separated clay from silt and sand. This mode also shows dominance of terrestrial signals that are associated with clay, including organics, total 210Pb, and clay minerals. Mode 2 explains 15.9% of the data, is dominated by provenance contrast between weathered granites from Zhe Min region and non-granitic sources from Changjiang. Mode 3 explains 14.3% of the data that reveals the contrast between terrestrial sourced coarse clastic sediment and silty organic marine material. In general, the co-variability of captured sediment was influenced by transport process and provenance. |
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