Sedimentation and resuspension across the central Louisiana inner shelf /
The sedimentation and resuspension across the central
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739888111&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The sedimentation and resuspension across the central Louisiana inner shelf were studied via integrated methods using particle settling trap deployments, optical sensing and bottom current measurements as well as geochemical analyses. Sediment traps were attached to LATEX A current-meter moorings at six sites along 90.5 [] W and 92 [] W west of the Mississippi Delta to form two cross-shore sections from a depth of 8 to 50 m. Traps were generally deployed and recovered every 6-10 weeks for 2.5 years (April 92 - July 94). The settling and resuspension fluxes, the percentage of organic carbon and carbonate, grain size distributions, and their spatial and temporal variability were determined. The shelf hydrography were examined based on data collected by 10 LATEX A hydrographic cruises during 1992-1994 in order to better understand the relationship between the sedimentation, resuspension processes and the environment. The cross shelf distribution of particulate matter concentration (PMC) during each of ten cruises were determined based on the particle beam attenuation coefficient (cp) calculated from transmissometer data, which were calibrated by simultaneous filtration data. The optical sensing revealed that the bottom nepheloid layer (BNL) was ubiquitous on the central Louisiana shelf. The sediment trap data strongly suggest that resuspension was dramatic and a common feature on the central Louisiana shelf during this study. The vertical profiles of total fluxes and particle composition, and the compositional similarity between the samples from traps 1 mab and those from the top of gravity cores in organic analyses including CPMAS 13C-NMR indicate resuspension in the region. The bed shear stress was calculated based on the law of the wall and the quadratic stress law, using bottom current meter data from these sites. Analysis of bed shear stress indicates that currents were sufficient on many occasions to resuspend bottom sediments. A quantitative relationship between the total flux I mab and bed shear stress was established via multivariate linear regression. The study suggests that the total fluxes 1 mab at a given site can be estimated based on an analysis of the bed shear stress measured, and a multivariate linear regression model. |
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| Item Description: | Vita. "Major Subject: Oceanography". |
| Physical Description: | xiii, 189 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 180-188. |