10-m Layer Research Articles

Heat transfer in the oceanic crust of the Brazil Basin

A detailed geothermal survey has been made on the western flank of the Mid‐Atlantic Ridge in the Brazil Basin where the crust is 20 m.y. old. The area is generally covered by a 150‐ to 200‐m thick layer of foraminiferal ooze, but basement outcrops are numerous. Sedimentary temperature profiles indicate anomalously low temperatures at the base of the sedimentary layer, which results from cold bottom water penetrating laterally into the upper igneous crust and absorbing much of the geothermal heat. Net influx rates of 10−8 m s−1 are implied by a simple aquifer model. A negative pressure drop across the sedimentary layer is required by this interpretation. Refraction studies indicate low seismic velocities (3.3 to 4.5 km s−1) near the top of layer 2, and a large velocity gradient with depth. The velocity structure in the upper kilometer of the crust is related to the porosity, from which it is inferred that permeabilities there are high. Many of the 52 temperature profiles show a significant decrease in gradient with depth. The curvature can be attributed to one or a combination of the following causes: (1) upward advection of pore water at rates of 10−7 s−1, (2) bottom water temperature variations, (3) variation of conductivity with depth, and (4) experimental errors. Interpretation of curvature in terms of an advective model leads to results hard to reconcile with present knowledge of pressure variations and permeabilities of the oceanic crust.

Polyunsaturated fatty acids in a lacustrine sediment as a possible indicator of paleoclimate

Polyunsaturated fatty acids ( C 18:2 and C 18:3 ω3 were analyzed in the upper 20m layer of a 200 m long sediment core taken from Lake Biwa. Concentration maxima occur in layers at depths of 0.2, 1–5, 11–12, and 16m. The vertical changes in the (C 18:2 C(C 18:0 ratio appear to correlate with paleoclimatic condition suggested from palynological evidence. On the basis of C 18:2 C 18:0 ratios, it was suggested that it has been colder at 200, 1000–4000, 15,000 and 20,000 yr BP than at other times.

Measured Effects of Vibratory Sheetpile Driving

The installation of sheetpiles using a vibratory hammer is becoming more common. However, this process induces vibrations into the ground which can be transmitted to nearby structures and which may produce settlements in sandy soil layers. A series of field case histories from San Francisco are reviewed where the effects of vibratory sheetpile driving were measured. Typically the soils at the sites consisted of a 10-m (33-ft) layer of loose to medium sand-rubble fill underlain by either dense natural sands or soft San Francisco Bay mud. Horizontal and vertical accelerations and velocities are reported, as well as ground settlements. Accelerations and velocities are found to diminish rapidly with distance from the pile, with greater damping effects observed for cases where softer soils underlie the fills. Where the sheetpiles encountered hard rubble objects, accelerations are double those of the normal case. Settlements are found to correlate with the density of sands in the fills and the level of acceleration.

Synthesis and gas chromatographic use of metal-containing surfaces

A variety of volatile metal halides were used in the gas phase to produce layers with thicknesses in the monomolecular range on Chromosorb W. The final layers result from subsequent treatment with H 2O, NH 3 or H 2. They could be considered to be of the “oxide”, “nitride” or “reduced” type, although no evidence for particular surface structures has been obtained. Layers were tested by gas chromatography directly and after attempted synthesis of an additional “bonded” Carbowax 20M layer. These procedures were successful (in terms of achieving inorganic layers in the monomolecular range and good chromatography with Carbowax 20M) in some but not all cases. The best materials were about equal in chromatographic performance to the best comparable phases containing no metals. “Bonding” of Carbowax could be achieved on several types of layers. For example, those containing Fe or Cr performed noticeably better than those containing Al or B. General uses of such materials are suggested.

Comparison of surface modification techniques used for the preparation of wall coated open tubular glass capillary columns

Comparison of different techniques for modifying internal glass surfaces to accept a substrate loading on wall coated open tubular columns (WCOT) were examined. Inner surfaces pretreated with a non-extractable Carbowax 20M layer, barium carbonate and silica whiskers were prepared and coated with a Carbowax 20M liquid phase. The columns were evaluated for efficiency, acidic-basic and adsorption properties, thermal stability and coating efficiency. Column performances were also assessed for deactivated surfaces. Each column was applied to a standard mixture of Aroclor 1016.

Fine-scale temperature structure in the bottom mixed layer on the Oregon shelf

Temperature and temperature-gradient records made as a freely-falling probe hit bottom show an extremely well-mixed layer on the Oregon continental shelf in September, 1974. Temperatures were uniform to within a few millidegrees in a 10-m deep layer. A reverse gradient of one to four times the adiabatic was found in the last 5 m or so, larger than the geothermal flux could maintain. The layer depth is similar to that of a turbulent Ekman layer. On vertical temperature-gradient spectra several subranges are seen. Estimates of eddy diffusivity by the Cox-Osborn-Hacker method agree within a factor of two with estimates calculated from the level of an assumed inertial sub-range in temperature gradient spectra. Possibly the layer is stabilized by a salinity gradient too small to be observed by the conductivity-temperature-depth probe, or by sediment load. Calculations of heat flux caused by the thermal storage of the sediments yield a flux of the correct order, but the opposite sign, of the calculated flux.

大阪湾における<i>Sagitta enflata</i>の進入条件について

In the previous paper, the author reported the distribution of Chaetognathe in the Harima-nada and Osaka Bay, with special reference to Sagitta enflata in 1965. The present paper deals with the hydrological conditions for S. enflata that entered Osaka Bay from 1965 to 1967.The results obtained are as follows: 1) S. enflata was first seen in the early part of May, at the earliest in the narrow southern part of Osaka Bay. Time of the extension of the distribution area of this species to northward in Osaka Bay was estimated to be during the period when the water temperature rised to 18-19°C. 2) As this species is euryhalic, no close correlation between the distribution density and the horizontal distribution of chlorinity at the 10M layer was noted. On the other hand, the densely populated area of this species fairy corresponds to the area with a transparency of above 5M.3) As mentioned above, even if the water temperature rised to 18-19°C, the entarance of this species seems to be late in case of low transparency, but may be fast with bight transparency in Osaka Bay. It was considerd that the entrance depended on the interaction between the neritic water mass and oceanic water mass in the bay at that time.

On the giant sea-salt particles in the atmosphere: II. Theory of the Vertical Distribution in the 10-m Layer Over the Ocean

The vertical distribution of giant sea-salt particles in the 10-m layer over the sea surface, where humidity, eddy diffusivity, etc., sharply change with height, is analytically studied. A steady state with no horizontal gradient and with a logarithmic distribution of wind speed is assumed, but the vertical distributions of temperature and vapor pressure are taken into account in such a way that each droplet is assumed to instantaneously attain its equilibrium salinity for the environmental air at each level, and to remain as a droplet of supersaturated salt solution when the relative humidity is lower than 75%. It is deduced that the vertical distribution of the number concentration of each class interval of mass of salt contained in a droplet should be approximately expressed by a straight line on a logarithmic diagram. Also, the logarithm of the ratio of the concentration of the particles at the sea surface and at the 10-m level is proportional to the two thirds power of the mass of salt, and inversely proportional to the wind speed at the 10-m level. The proportionality factor is approximately a function of the relative humidity at the 10-m level and a friction factor. This proportionality factor is calculated for various values of the variables and the effect of wind speed and relative humidity on the vertical distribution of particles is predicted. When this result is applied to data of the concentration and the effective production rate of sea-salt particles at the 10-m level compiled in the previous paper, complicated features disappear to give very simple patterns of the production rate or the surface concentration of sea water droplets as a function of wind force and of mass of salt. This represents predicted processes of production of sea-salt particles at the ocean surface, and gives some agreement with the author's 1961 wind flume experiment. DOI: 10.1111/j.2153-3490.1965.tb01429.x

ゴマサバの仔,稚魚の分布移動と環境要因の研究-II

The present paper gives the observations reterable to the distribution of mackerel larvae, P. tapeinocephalus, collected by larval net operated at the six layers of 0 (surface), 10, 20, 30, 40, and 50 meters in the region covering Kagoshima Bay and the Osumi channel, and some considerations, especially on the collecting method in relation to the current velocity. The results (Tables 2 and 3) are summarized as the following lines. 1) From April to June 1960, and in March 1961 the mackerel larvae are found at all the observed layers but 50 meter one, in the fishing ground (of the adult fish) of the said region. 2) The collected larvae are of 3.1-21.0mm in total length. Most of them are small, of less than 10mm in total length (Fig. 3). 3) The collection rate from the 10m layer rises to the highest, that is of 67%. 4) The large number of samples are collected under the conditions of 18-19°C in water temperature, and 34.7-34.8% in salinity (Fig. 4).

ゴマサバの稚・仔魚の分布移動と環境要因の研究-I

The distribution of the mackerel-larvae, P. tapeinocephalus was studied at the three sections, at the surface, 10m layer and 20m layer around Osumi Islands; The results obtained are as follows: 1) Mackerel-larvae were collected at the three layers (surface, 10m layer, 20m layer) in the fishing ground and the adjacent sea from February to May (1958, '59) and the water temperature was varying 16.3-22.4°C). 2) The total length of the larvae was within 4.8-11.8mm, and the larvae-size frequency showed almost the same figures through each month. 3) As the Table 2 shows, the collection-rate (collection frequency/net drawing frequency×102) showed highest at the 10m layer, and the seasonal change was hardly observed. The collection-rate in the surface showed high rate in the morning, and it became low in the daytime. And the collection-rate in the 20m layer was somewhat lower than that of 10m layer, and the seasonal change was small. 4) The vertical stability change of the layer from surface to 10m is assumed to have some influences upon the distribution of the larvae in the surface layer.