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Time series of the vertical distribution of resuspended matter and bottom current were collected concurrently during summer at a few anchored stations in the Seto Inland Sea. The vertical distribution of resuspended matter was measured every hour for about one tidal cycle and the three components of current fluctuation were obtained at each sampling station. Current data at each sampling station show that the bottom is hydraulically smooth.Assuming that the averaged vertical distribution of resuspended matter for one tidal cycle shows a steady state distribution, the settling velocityWs of resuspended matter is estimated to be in the range of 1.2×10–2 to 5.7×10–2 cm sec–1 from analysis of the averaged distributions.The relation between the erosion rate and the bottom shear stress for this study area is investigated and is compared with that for other areas. The results show that the erosion of sediment in the Seto Inland Sea during summer occurs even due to the low bottom shear stress which is considered as almost smooth hydraulically. 相似文献
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The vertical distributions of suspended particles in Osaka Bay were measured by using anin situ beam attenuation meter. The concentration of suspended particles near the bottom increases rapidly toward the bottom where size of sediment is in a range of silt. The settling velocity of suspended particles near the bottom was measured with the use of a settling tower in the laboratory. The settling velocity of the suspended particles with diameter from 10 to 100m is 2×10–3cm s–1 to 5×10–2cm s–1. The density of the particles ranges from 2.0 to 1.1 and decreases with increasing particle diameter. 相似文献
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Measurement of the vertical distribution of total suspended matter (TSM) was carried out during summer throughout the Seto Inland Sea. TSM concentration near the bottom is influenced significantly by water movement and turbid bottom water is observed in all areas where median grain size (Md) of the bottom sediment is more than 47gf. The high concentration of TSM near the bottom may be due to resuspension of the surface layer of bottom sediments. Comparison of the organic content of the resuspended matter with that of the bottom sediment shows that the resuspended matter contains more organic matter with a lower C : N ratio than the bottom sediment. The C : N ratio of the resuspended matter is similar to that of TSM in the surface layer of the water column. It is thought that TSM in surface waters sinks and settles on the surface of the bottom sediment. This deposited material is then easily resuspended in the water column by tidal currents before becoming permanently incorporated into the bottom sediment. 相似文献
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The observed relation between the vertical distribution of suspended matter and the size distribution of bottom sediment in
the Hiuchi-Nada area indicates that a turbid bottom water layer exists above the bottom when the bottom sediment is of silt
size. The turbid bottom water is thought to be produced by resuspension of bottom sediment.
Measurements of the temporal variation of resuspended matter and water movement near the bottom was carried out for one full
tidal cycle at an anchored station. The concentration of resuspended matter reached a maximum at the time of strongest ebb
and flood flow. 相似文献
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Takayuki Shiozawa Kichiichiro Kawana Akira Hoshika Terumi Tanimoto Osamu Takimura 《Journal of Oceanography》1977,33(6):350-356
From July to November, the thermocline which has strong temperature gradient (0.7C m–1) is formed in the bottom water of Beppu Bay, and it prevents the downward mixing of surface water. This has caused the bottom water of the basin to become depleted in oxygen, and in November the bottom water below about 60 m depth becomes anoxic. Accordingly manganese and iron are reduced and more soluble under the anoxic condition, those concentrations are high relative to surface water, and the maximums are 1,240g l–1 and 80g l–1. Under the anoxic condition, the flux of dissolved manganese from the sediment is about 10g cm–2 day–1. 相似文献
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Naoki Itoh Youhei Kawana Satoshi Nozawa Yasuharu Kohyama 《Monthly notices of the Royal Astronomical Society》2001,327(2):567-576
We extend the formalism for the calculation of the relativistic corrections to the Sunyaev–Zel'dovich effect for clusters of galaxies and include the multiple scattering effects in the isotropic approximation. We present the results of the calculations by the Fokker–Planck expansion method as well as by the direct numerical integration of the collision term of the Boltzmann equation. The multiple scattering contribution is found to be very small compared with the single scattering contribution. For high-temperature galaxy clusters of the ratio of both the contributions is −0.2 per cent in the Wien region. In the Rayleigh–Jeans region the ratio is −0.03 per cent. Therefore the multiple scattering contribution is safely neglected for the observed galaxy clusters. 相似文献
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