Control of Phosphate Concentration through Adsorption and Desorption Processes in Groundwater and Seawater Mixing at Sandy Beaches in Tokyo Bay, Japan     

Masahiro Suzumura  Shingo Ueda  Eiichi Sumi 《Journal of Oceanography》2000,56(6):667-673

Field observation was conducted to monitor phosphate concentrations in groundwater and seawater mixing at two sandy beaches in Futtsu and Miura in Tokyo Bay, Japan. Dissolved phosphate concentrations were measured along transects from fresh groundwater aquifer to seawater adjacent the beaches. The concentrations were often high (up to 46 µM) in fresh groundwater samples (Cl^– < 0.2). Coastal seawater, on the other hand, exhibited low phosphate concentrations (1.5 µM or less). Along the transects, phosphate generally displayed non-conservative behavior during mixing of fresh and saline waters in the aquifer; concentrations as high as 100 µM were found around the upper limit of seawater intrusion (Cl^– = 2). Laboratory experiments were executed to identify the processes that control the phosphate behavior in the mixing processes. The results revealed that adsorption-desorption processes by the aquifer sand particles could significantly control the phosphate concentrations in the groundwater. Furthermore, the adsorption and/or desorption was found to be a function of salinity; the equilibrium concentration of dissolved phosphate in slurry of sand and water was the highest in freshwater and decreased considerably in saline water. The extreme concentration of phosphate may be caused by release from sand particles coinciding with the rapid change in salinity with tide.  相似文献   

Experimental Study of Factors Controlling Sorption of Heavy Metals on Ariake Clay and Implication for Practice     

Y. J. Du  S. Hayashi 《Marine Georesources & Geotechnology》2006,24(2):103-118

A series of batch tests have been presented to investigate the effects of solid-solution contact time, solid:solution ratio, and pH of solution on sorption of Cd²⁺ and Pb²⁺ on Ariake clay from Kyushu region of Japan. The results show that, among the three investigated factors, solid:solution ratio (SD/SN) seems to be the crucial controlling factor. The Freundlich sorption parameters determined from the batch tests were applied to a typical field landfill in which the Ariake clay was used as soil barrier. The impacts of the landfill were assessed by numerical analysis. Based on the analysis result, the significance of selecting proper solid:solution ratio for determining sorption parameters from batch test has been discussed.  相似文献   

Formation of thermohaline front by cooling of the sea surface and inflow of the fresh water     

Masahiro Endoh 《Journal of Oceanography》1977,33(1):6-15

A numerical study of characteristics of the front formed by cooling of the sea surface and inflow of the fresh water is made within a vertical two-dimensional plane without the rotation of the earth. The convective adjustment technique is employed to parameterize the small scale convective overturning process.A sharply edged shelf causing the marked difference of the heat capacity of the water columns between over the shelf (50 m depth) and in the deeper region (150 m depth), is responsible for the formation of a thermal front over the shelf edge and two cell circulations of the same sense with each other adjoining at the frontal region.Inflow of the fresh water at the upper region of the coast (which is equivalently replaced by the outflow of the salt from the same region) adds a circulation of the opposite sense to the above ones, which transports the water of low salinity and low temperature offshore and forms a sharp front both of temperature and salinity with the offshore water of high salinity and high temperature. This thermohaline front or Oceanic front has a remarkable character that the horizontal density gradient is minimal at the front due to the counteracting contributions of temperature and salinity to density. Response of this front to the sudden ceases of the surface cooling and the fresh water supply, is also studied in order to understand its transient behaviors.  相似文献   

A numerical investigation of western boundary currents in subtropical and subpolar gyres with a barotropic model     

Masahiro Endoh 《Journal of Oceanography》1973,29(4):148-154

Dynamics of western boundary currents in the subtropical and subpolar gyres are studied as a source-sink flow of barotropic fluid by means of numerical integration of the time-dependent non-linear vorticity equation. The bottom topography consists of a continental shelf of uniform slope (120 km wide) parallel to the straight western coast and a flat bottom of uniform depth. The steady solution in the case of low Reynolds number (Re≦100) shows the vorticity balance of the western boundary current between theβ-, diffusion-, and bottom relief terms. The cuspidated flow of the western boundary current in the subpolar gyre is observed as a compensating flow for the subtropical western boundary current separating from the western coast. In the case of Re=350, the zonal current separating from the coast meanders with the wave length of the stationary Rossby waves. It is shown that in the present model the separation of the boundary current is controlled by the planetary vorticity (f) of the fluid particle in the boundary flow, with which the same particle flows out the eastern wall at the corresponding latitude. The decrease of the efflux width increases the intensity of the non-linear overshooting of the boundary current separating from the western coast.  相似文献   

The study of ocean circulation dynamics with numerical models     

Masahiro Endoh 《Journal of Oceanography》1980,36(2):134-140

Summarized is the author's study of the ocean circulation dynamics with numerical models, for which he was honored by the Okada Prize (1979). Cited topics are formation of the western boundary current and its variation associated with imposed wind stress, some effects of a marine ridge on the boundary current, coastal upwelling circulation and coastal thermohaline front formation. Recent modelling efforts in Japan, specifically on numerical study of ocean circulation dynamics are also reviewed.  相似文献   

Diagenetic behavior of manganese in Tokyo Bay sediment     

Masahiro Sakata  Yasushi Kitano  Eiji Matsumoto 《Journal of Oceanography》1981,37(4):212-217

To understand the behavior of manganese in diagenetic processes in sediments of an enclosed bay which is similar to those of an estuary, chemical analyses have been carried out on both sediment and interstitial water of a core sample collected from Tokyo Bay. The results suggest that redistribution of manganese takes place within the sediment as a result of the dissolution of buried manganese oxides and hydroxides under reducing condition, the downward diffusion of Mn²⁺ through the interstitial water toward lower layers and then the precipitation of carbonate. The carbonate formed in the sediment contains managanese carbonate probably as a solid solution between calcitic calcium carbonate and manganese carbonate.  相似文献   

Policies governing the distribution of by-products from scientific and small-scale coastal whaling in Japan     

Aiko Endo  Masahiro Yamao 《Marine Policy》2007

The Japanese government is committed to resuming sustainable commercial whaling, both on the high seas and along the Japanese coastline. To this end scientific whaling programs are supported with public money and the byproducts of the catch are distributed to the public and utilized in a variety of ways. Here we review the policies which govern how these byproducts are disseminated within Japan, as well as how the population as a whole makes use of whale resources. Possibilities for the future, if and when the international moratorium on commercial whaling ends, are also discussed.  相似文献   

Double-celled circulation in coastal upwelling     

Masahiro Endoh 《Journal of Oceanography》1977,33(1):30-37

Simple numerical experiments on two-dimensional coastal upwelling are made with emphasis on the role of non-geostrophic solenoidal field of density in the formation of double-celled circulation and multi-celled density front. Geometry of shelf and slope is not taken into account. Existence of poleward undercurrent presumably caused by the longshore variation of the large scale pressure field is also suppressed for the sake of simplicity.The results are, (1) double-celled circulation revealed in the present experiment is closely related with the internal frictional layer, where the horizontal density gradient balances with the vertical gradient of the longshore velocity and the vertical diffusion of the vorticity. (2) density front formed by the emergence of the pycnocline to the sea surface is successively advected offshoreward by the Ekman transport. (3) the pycnocline intersecting the sea surface forms the density front which is nearly vertical on account of the small scale convection. The surface currents converge at the front and construct an anti-clockwise circulation (viewed from the lee side). (4) small coefficient of eddy viscosity and strong wind stress lead the Ekman transport unstable and form a multi-celled structure in the frontal region.  相似文献   

Reply to Bassin and McKee's comments on “Large suspended particle”     

Masahiro Kajihara  Katsuhiko Matsunaga  Yoshiaki Maita 《Journal of Oceanography》1976,32(2):93-96

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Relationships between trace element concentrations and the stable nitrogen isotope ratio in biota from Suruga Bay,Japan     

Masahiro Sakata  Ai Miwa  Satoshi Mitsunobu  Yasuhiro Senga 《Journal of Oceanography》2015,71(1):141-149

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