latest quaternary oceanographic changes in the okhotsk sea based on diatom records abstract the okhotsk sea is a locus of the north pacific intermediate water formation today the formation of the okhotsk intermediate water is linked with seasonal sea ice cover diatom records from the okhotsk sea show the following 1 during the last glacial maximum between 21 000 yr b p and 18 000 yr b p sea ice covered the western side of the sea throughout the whole year but the eastern part was open this permitted more efficient heat exchange with the atmosphere than waters and hence ventilation of the glacial okhotsk sea waters which in turn caused a greater extent of intermediate water formation through the bussol strait 2 the perennial sea ice cover extended northward and sea ice was present throughout the whole year over a great part of the sea except for the eastern part between 18 000 yr b p and 17 000 yr b p 3 the ice free area extended greatly to the south during the interval between 17 000 yr b p and 11 000 yr b p 4 there was no perennial ice cover over the whole sea and the ice free area that appeared as the seasonal ice area began to extend to the western part between 11 000 yr b p and 8 000 yr b p 5 after 8000 yr b p the ice free waters contracted to the present extent

vertical soil water movement in a tropical rainforest catchment in northeast queensland in a tropical rainforest catchment shallow piezometers respond almost instantaneously to rainfall but the dominant ground water recharge mechanisms are not well understood to improve understanding the downward movement of soil water on a runoff plot was traced using tritiated water injected at 0 20 m below the surface which marks the lower boundary of active subsurface storm flow the tritium pulse was translated slowly down the profile apparently dominated by interstitial piston flow on the lines described by zimmermann s theoretical model this recharge mechanism accounted for about 35 per cent of rainfall or 50 per cent of throughfall the pulse s advance may have also been delayed by the upward movement of soil water indicated by the distribution of hydraulic potential under different hydrological conditions the result was an increase in soil water transit time particularly below 1 0 m there was also evidence in the tracer profiles for rapid by pass flow but the volumes concerned could not be quantified in this experiment

late quaternary paleoceanographic changes in the southwestern okhotsk sea evidence from geochemical radiolarian and diatom records abstract high resolution analyses of geochemical parameters biogenic opal calcium carbonate organic carbon and nitrogen and microfossil assemblages diatoms and radiolarians on core md01 2412 clarified detailed paleoceanographic changes such as sea ice cover and biological production in the southwestern okhotsk sea during the last 115 kyr an age model of core md01 2412 was established based on 18o stratigraphy accelerator mass spectrometer ams 14c and tephrochronology sea ice history reconstructed by siliceous microplankton records indicated that the present sea ice condition was formed during the last 8 kyr only during marine isotope stage mis 2 was the duration of sea ice cover in this region much longer than that of today 4 5 months a year two diatom species thalassionema nitzschioides and fragilariopsis doliolus revealed that the soya warm current water swcw flowed into the okhotsk sea near the site of core md01 2412 during the last 12 14 kyr and during mis 5a and was associated with sea level rise biological productivity rapidly increased during mis 1 associated with sea ice retreat two major increases of organic carbon oc contents wt and corg n ratios were observed and the timings of these events were 15 8 16 7 ka event 1 and 13 1 13 6 ka event 2 corresponding to these events the abundance of cycladophora davisiana an intermediate water dwelling radiolarian species increased this high c davisiana abundance can be correlated to the input of terrestrial organic matter from the submerged shelf to the intermediate water apart from the radiolarians the production of diatoms in the surface waters was suppressed by the development of well stratified surface water along with sea ice melting during the early holocene diatom production increased gradually during the last 10 kyr with enhanced vertical mixing

sea surface temperature and salinity changes near the soya strait during the last 19 ka past sea surface temperature sst and salinity sss changes in the northeastern east sea japan sea since 19 cal ka bp have been reconstructed by using an alkenone unsaturation index and the oxygen isotope ratio of planktonic foraminifera neogloboquadrina pachyderma s in core mr0604 pc03b coretop alkenone temperature and calcification temperature correspond to the temperature of seawater in summer and spring at the depth of 10 30 m respectively based on the records from this core and previous studies spatio temporal changes in alkenone temperature of the east sea japan sea have been reconstructed to investigate changes of surface circulations and the subpolar front spf position during the transitional period from the glacial to the holocene the sst was lower about 2 3 c than that of today and the sss dramatically increased at that time in the entire east sea japan sea but it was still lower than that of today however the northern sss was higher than that of the southern part the source of the cold and saline seawater could have been the oyashio current oy inflow from the north not the tsushima warm current twc inflow from the south probably sea level rose rapidly at that time there might be no strong development of the spf during the transitional period due to the restricted inflow of the twc during the early holocene the sst and sss of the east sea japan sea increased compared to the transitional period due to increased seawater exchange through straits the spf was tilted orienting from southwest to northeast because the inflow of the twc was not fully developed due to lower sea level subsequently the surface condition of the east sea japan sea was similar to that of today at 6 cal ka bp the forerunner of soya warm water fsww that flowed out through the soya strait in early spring did not affect the formation of the okhotsk sea intermediate water and the north pacific intermediate water during the glacial and interglacial periods

formation of 26 8 26 9 σθ water in the kuril basin of the sea of okhotsk as a possible origin of north pacific intermediate water by using all japanese hydrographic data obtained south of 55 n in latitude in the sea of okhotsk we compile a data set for this study our investigations with these data show that a large quantity of relatively cold fresh oxygen rich homogeneous intermediate water with a density range of 26 8 to 26 9 exists in the kuril basin we name this intermediate water the kuril basin intermediate water kbiw results of isosteric analyses show that a possible origin of kbiw is located in a region off the hokkaido coast in the southwestern sea of okhotsk we suggest that kbiw is produced by the isopycnal mixing of relatively dense soya warm water which appears only in early spring with the colder fresher water which originates from the northwestern okhotsk finally we demonstrate that kbiw may be a source water of the north pacific intermediate water npiw because it has the same density range and water properties

evaluation of sample quality of sensitive clay using intrinsic compression concept a simple index the degree of sample disturbance is proposed in this study to quantitatively evaluate the quality of sensitive clay samples based on the concept of void index proposed by burland in 1990 the degree of sample disturbance is defined as the ratio of the difference between the in situ void index and the void index of the undisturbed sample tested in the laboratory to the difference between the in situ void index and the void index of the completely remolded clay all these indices are determined at the same effective overburden stress theoretically the degree of sample disturbance varies from 0 perfect undisturbed sample to 100 completely remolded sample the proposed index is used in this study to evaluate the sensitive ariake clay in japan oedometer tests on undisturbed samples of natural ariake clay obtained from the field using the current sampling practice in japan show the degree of sample disturbance ranging from approximately 5 to 38 the clay sample with an in situ void index closer to the intrinsic compression line has a lower degree of sample disturbance in addition a series of consolidation and unconfined compression tests were conducted on artificially disturbed samples in the laboratory to demonstrate the change of consolidation yield stress unconfined compressive strength and compression index with the degree of sample disturbance a simple method is proposed in this paper to correct the mechanical parameters measured in a laboratory setting considering the degree of sample disturbance

satellite observations of the ice cover of the kuril basin region of the okhotsk sea and its relation to the regional oceanography for the period 1978 1982 this paper examines the nature of the sea ice which forms over the kuril basin of the okhotsk sea and describes the impact of this ice on the regional oceanography the paper compares the oceanographic behavior during the heavy ice season associated with the cold 1979 winter with the behavior during the lighter ice years of 1980 and 1982 examination of the oceanography in the okhotsk and the adjacent pacific shows that the early summer water column structure depends on the heat loss from the okhotsk during the preceding ice season the total amount of okhotsk ice formation and specifically the amount of ice formation in the kuril basin following the 1979 ice season the upper 200 300 m of the kuril basin waters were cooler less saline and richer in oxygen than for the other years this modification appears to be a process local to the kuril basin driven by eddy induced mixing local cooling and ice melting in the depths 300 1200 m the water modification is caused by the advection of water from the northern okhotsk for 1979 this deeper water is also less saline colder and richer in oxygen than for the lighter ice years the water modified in the okhotsk enters the adjacent north pacific through the bussol strait where for 1979 the adjacent waters are also cooler less saline and richer in oxygen down to a depth of 1000 m than for the lighter ice years

estimation of the moisture supply capacity of some swelling clay soils in the netherlands abstract the growing season in the netherlands is characterized by a precipitation deficit evapotranspiration surplus in most years optimal crop development requires therefore moisture supply by the soil in addition to natural rainfall moisture can either be supplied as available water from the root zone or as an upward flux from the water table towards the root zone a computer model was used to simulate soil moisture regimes of a swelling clay soil the model uses thickness of the root zone hydraulic conductivity and moisture retention data for the soil horizons and needs depth to water table and climatic data as boundary conditions existing flow theory does not describe flow of water in swelling clay soils where dessiccation is associated with the formation of both vertical and horizontal cracks in the soil cracks strongly influence the flow regime by reducing upward fluxes to the root zone horizontal cracks and by inducing rapid downward flow of water along vertical cracks short circuiting a field technique is used which allows an estimate of the effective reduction of the hydraulic conductivity due to horizontal crack formation this reduction is a function of the pressure head the amount of short circuiting was estimated by analysing the occurrence of heavy and very heavy rains over a 30 year period since these rains are likely to partly bypass the root zone short circuiting effectively increases the precipitation deficit the simulation model was experimentally validated using field data for the growing season of 1979 calculated moisture conditions in the soil agreed only with those that were measured in situ when the effects of both horizontal and vertical cracking were considered additional runs with the validated model were made using statistically expressed climatic data and selected water table levels results allow an estimate of the amount of water which needs to be supplied to the soils so as to achieve potential evapotranspiration

dense water production on the northern okhotsk shelves comparison of ship based spring summer observations for 1996 and 1997 with satellite observations for the northern okhotsk sea polynyas five russian ctd surveys taken during 1995 to 1997 are used to examine the evolution of the polynya dense water the surveys show that consistent with other investigations the largest potential densities are 26 99 and the densest water occurs in sakhalin and shelikhov bays the surveys also suggest that the shelikhov water drains directly into the deep okhotsk while on the northern shelves gravity currents transport the dense water west to sakhalin bay for comparison determination of the polynya sizes and ice production from satellite passive microwave and meteorological observations shows that polynyas occur on the northwest shelf nws between ayan and okhotsk city on the northern shelf between okhotsk city and magadan and in shelikhov bay in contrast the observations show that sakhalin bay is a region of land fast ice with no polynyas so that the dense water observed here cannot form locally for all polynyas the satellite observations show that the nws contributes 60 to 70 of the total ice production and due to the warmer 1997 air temperatures the 1996 production is about 1 5 times the 1997 value an estimate of the ice production from the surveys shows a similar regional distribution and enhancement of the 1996 production with the satellite and ship estimates in agreement within their error bars finally analysis of the dense water outflow shows that the upper okhotsk sea mode water has a renewal time of about 4 years the lower part about 14 years

influence of okhotsk sea intermediate water on the oyashio and north pacific intermediate water 1 the volume transport between the okhotsk sea and western subarctic north pacific is estimated on the basis of direct current measurements made by a lowered acoustic doppler current profiler ladcp and hydrographic data taken in august and september 1999 near the kuril islands the estimated southwestward oyashio transport was 11 12 sv 106 m3 s in the density range of 26 7 27 4 the net transport of the okhotsk sea water osw was 3 4 sv of which 1 3 sv was coming out through the kruzenshterna strait and 2 1 sv was coming out through the bussol strait a bidirectional flow was observed in the bussol strait inflow in the northern part of the strait and outflow in the southern part 0 6 sv of osw recirculated along the western subarctic gyre the remaining 2 8 sv of osw could contribute to the formation of north pacific intermediate water as a cross subarctic front transport along the coast 1 4 sv and across the offshore saf 1 4 sv the production rate of the dense shelf water dsw through sea ice formation was estimated to be at least 1 1 sv when the intermediate osw is formed through the mixing between cold and fresh dsw and warm and salty waters from the pacific and japan sea 16 8 tw 1012 w of heat 0 007 sv of freshwater and 2 3 105 kg s of salt are exchanged the net flux of oxygen and anthropogenic co2 ex co2 from the okhotsk sea into the pacific in 26 7 27 4 is estimated to be 10 5 and 2 1 tmol yr 0 025 gtc yr respectively the ex co2 transported by osw accounts for about 10 of the accumulation of ex co2 in the subarctic and subtropical pacific

on compression characteristics of ariake clays j b burland proposed that the void index aids in assessing the compressibility of various sedimentary clays the extensive data on sensitive ariake clays are used in this study to investigate the

a field method for measuring short circuiting in clay soils abstract a field method is described for measurement of short circuiting which is defined as vertical flow of free water along the walls of continuous macropores in unsaturated soil a cylinder with a diameter and height of 20 cm is filled with undisturbed surface soil and is placed on a perforated disk in a funnel the funnel is supported to allow periodic measurement of the volume of outflow from the soil the assembly is placed along the track of a spray gun which is commonly used for sprinkling irrigation at least four samples can be measured during one run the method is illustrated by discussing the measured short circuiting in surface soils of 1 a heavy clay soil 2 a light clay soil with two different types of structure in and adjacent to potato ridges and 3 a heavy clay soil with two types of surface microrelief short circuiting is unfavourable because water moves rapidly beyond the root zone without moistening and leaching the soil between the macropores the water may carry surface applied fertilizers

submesoscale eddies near the kuril straits asymmetric generation of clockwise and counterclockwise eddies by barotropic tidal flow 1 high spatial resolution thermal infrared tir images derived by the landsat thematic mapper tm sensors show the presence of numerous small scale eddies near the kuril islands as the diameters of these eddies range from around 2 to 30 km i e submesoscale they are much smaller than the eddies previously reported in this region several tens to some hundreds of kilometers in diameter our simulations suggest that small scale eddies similar to those observed in the satellite data are generated by diurnal barotropic tides the eddy generation is well defined from etorofu friza to the onnekotan straits and it is caused by the effects of coastal boundaries and the stretching of water columns which lead to eddy growth even after eddies have left the coast we find that the counterclockwise eddies are generally larger in number and size and stronger in vorticity and surface height than the clockwise eddies in both the gradient and cyclostrophic wind balance regimes the possible causes of such asymmetry are 1 the effect of planetary vorticity tube stretching which can be significant even when the final relative vorticity becomes much greater than planetary vorticity and 2 asymmetric advection by the rotating tidal flow which advects counterclockwise eddies offshore but clockwise eddies onshore these eddies induce strong stirring with a maximum apparent diffusivity of 108 cm2 s 1 the numbers properties and mixing effects of eddies vary greatly with the spring neap cycle

why is the spreading of the north pacific intermediate water confined on density surfaces around σθ 26 8 abstract the north pacific intermediate water characterized by a salinity minimum confined to density surfaces of 26 7 26 9 exists throughout the subtropical gyre and has been observed to originate in the subarctic north pacific the physical processes that determine the density range on which the npiw resides are not yet well understood this study attempts to clarify these processes by combining observational data and a simple advection diffusion isopycnal model due to the regional excessive precipitation over evaporation the salinity in the upper layer subarctic north pacific generally decreases with decreasing water depth both alongisopycnal advection and diffusion work to carry this salinity depth characteristic into the subtropical circulation for the isopycnal surfaces overlying the npiw however this transport mechanism is hindered by the seasonal outcropping the outcropping not only blocks the fresh subarctic water from advecting and diffusing along these isopycnals into the subtropi

ventilation of north pacific intermediate waters the role of the alaskan gyre hydrographic data tritium data and potential vorticity calculations suggest that although north pacific intermediate water is formed in the northwest the alaskan gyre might be an additional ventilation site the proposed ventilation is quantified by a vertical column tritium inventory which indicates an excess of 0 08 kg of tritium in the alaskan gyre an evaluation of the energy stored in the water column and of wind and buoyancy forcing shows that during winter conditions enough energy can be pumped into the system to force 26 80 to outcrop in the alaskan gyre model results suggest that relatively limited outcrops in time and space tens of days and several hundred kilometers in diameter can account for the excess tritium

chlorofluorocarbons in the sea of okhotsk ventilation of the intermediate water 1 ventilation of the intermediate layer in the sea of okhotsk is studied with regard to the ventilation of north pacific intermediate water npiw measurements of chlorofluorocarbons cfcs from 1998 to 2000 reveal that the okhotsk intermediate water is ventilated in two ways the first consists of dense water formation in the polynyas that form on the northern shelves during winter measurements show that on the northwestern shelf because of atmospheric cooling and brine rejection the cold water that forms is dense enough to enter the intermediate layer the cfc concentration in this dense shelf water dsw is high and almost saturated with respect to atmospheric cfcs indicating that the dsw experiences active air water gas exchange during its formation away from the shelves the cfc distribution shows that the dsw directly ventilates the upper level of the okhotsk sea intermediate water osiw the second ventilation process is driven by the strong tidal mixing around the bussol strait the observed distribution of cfcs at the 27 4 level suggest that diapycnal mixing around the strait transports cfcs from the surface to this deeper layer ventilating the osiw combination of both processes means that the osiw is more ventilated than pacific water at the same density levels

late glacial to holocene radiocarbon constraints on north pacific intermediate water ventilation and deglacial atmospheric co2 sources abstract radiocarbon reconstructions of past ocean ventilation rates constrain oceanic sources and sinks of co2 and mechanisms of subsurface hypoxia here 14c in coexisting benthic and planktonic foraminifera from a sediment core 682 m deep off southeast alaska documents paleoventilation over the past 17 000 years a chronology based on calibrated planktonic foraminiferal dates consistent with independent terrestrial dates for regional glacial retreat yields deglacial projection ages moderately greater than those of the holocene suggesting comparatively limited ventilation the observed holocene increase of apparent ventilation at intermediate depths tracks inundation of the bering strait between 11 800 and 13 200 years ago suggesting that flooding of continental shelves and export of low salinity surface waters to the arctic enhanced intermediate water formation in the north pacific an abrupt increase in the benthic planktonic radiocarbon age gradient implying homogenization of abyssal radiocarbon in deep and intermediate waters aligns with the younger of two episodes of rapid rise of atmospheric co2 and depletion of atmospheric c 14 during deglaciation 11 500 13 000 years ago suggesting the north pacific as a possible pathway for venting of oceanic co2 to the atmosphere during the second half of the deglacial transition

interannual to decadal variability in the southern okhotsk sea based on a new gridded upper water temperature data set 1 a new gridded water temperature data set of upper 200 m depths 0 50 100 200 m depths for the okhotsk sea was produced using an optimal interpolation technique from 1950 to 1996 using oceanographic observations in the world ocean database 1998 temperature variability at 50 100 and 200 m depths in the southern okhotsk sea south of 52 n in the warm season may october was investigated by an empirical orthogonal function eof analysis from 1958 to 1994 for which sufficient data exist for an eof analysis the first eof mode has a monopole structure with the maximal amplitude in the kuril basin and the corresponding principal component pc exhibits prominent quasi decadal variability the first eof mode is closely related with the wintertime december february sea surface temperature anomalies over the subarctic front or oyashio front in the north pacific and with wintertime sea level pressure slp differences between northern eurasia and the northern north pacific this suggests that the temperature changes in the okhotsk sea are caused by changes in the strength of the asian winter monsoon which are associated with the slp difference a quasi decadal oscillation similar to that of the pc 1 is observed in the slp difference since the 1960s and shared by the polar eurasian pol pattern arctic oscillation ao and north atlantic oscillation nao some hints of the relating variability are observed in coastal sea level difference between wakkanai and abashiri which was used as a proxy for transport in the soya warm current also some features of sea ice extents co vary with the pc 1

distribution and modification of north pacific intermediate water in the kuroshio oyashio interfrontal zone abstract a multiship ctd survey was conducted in the kuroshio oyash interfrontal zone in the area of 30 41 n 140 e 180 from may to june 1992 to examine the distribution modification process and formation site of north pacific intermediate water npiw low salinity oyashio water and high salinity kuroshio water merge along the kuroshio extension just off the east coast of japan and together flow eastward eastward geostrophic transport and salinity across the kuroshio strong current indicate that the mixture of the kuroshio and oyashia waters along the kuroshio extension can produce new npiw transport estimate suggests that the new npiw bifurcates into the interfrontal zone and into the recirculation of the subtropical gyre a salinity minimum structure can he also created due to the isopycnal mixing along the kuroshio extension between the oyashio and kuroshio waters which have different salinity and vertical velocity structures the low salinity oyashio water seen along the oyashio branches and t

study of the structure of a sensitive champlain clay and of its evolution during consolidation scanning electron microscopy and mercury intrusion porosimetry are used in parallel to identify the structure of a medium sensitivity champlain clay the clay structure is observed firstly on intact remolded and oven dried soils and secondly on soils consolidated at various levels in one dimensional compression both methods of investigation reveal for the intact soil the existence of an aggregated structure characterized by an interaggregate and an intra aggregate porosity remolding affects interaggregate links but does not destroy aggregates the observation of clay structure at various levels of one dimensional compression shows that the collapse of the structure is progressive the largest interaggregate pores being the first affected as the consolidation proceeds smaller and smaller pores are affected for a given pressure increment only the largest existing pores are affected a structure anisotropy has been seen to develop with increasing compression the scanning electron microscope and the me

the generation of large amplitude unsteady lee waves by subinertial k1 tidal flow a possible vertical mixing mechanism in the kuril straits numerical experiments with a two dimensional nonhydrostatic model are performed to investigate tidally generated internal waves in the kuril straits and their effect on vertical mixing the results show that sill scale internal waves at the k1 tidal frequency are confined to the sill slopes because the k1 tide is subinertial in the kuril straits in contrast to previous theories the authors show that intense short internal waves generated at the sill breaks by the subinertial k1 tidal current can propagate upstream as the tidal current slackens theoretical considerations identify these short waves as unsteady lee waves which tend to be trapped at the generation region and grow into large amplitude waves eventually inducing vigorous mixing along their ray paths in particular superposition of a propagating unsteady lee wave and a newly generated lee wave over a sill causes significant wave breaking leading to a maximum vertical diffusivity of 103 cm2 s21 this quite intense mixing reaches down to the density layer of the north pacific intermediate water npiw in contrast the m2 tidal current does not cause such strong vertical mixing because most of generated internal waves propagate away as first mode internal tides and because the barotropic flow amplitude is small the authors therefore suggest the possibility that generation of lee waves through interactions between the k1 current and the bottom topography of the kuril straits contributes to the observed modification of the okhotsk sea water required in the formation of the npiw

water movement and soil swelling in a dry cracked vertisol abstract vertisols are widely used for irrigated rice in the senegal river basin where farmers are increasingly reporting problems with soil salinization water movement at the onset of the growing season when soils are dry and cracked may have a large impact on soil salinity and water economy water movement and soil swelling processes were studied in a dry cracked vertisol in the senegal river valley surface irrigation and simulated rainfall intensity 88 mm h 1 on cracked 2 25 m 2 plots crack width 0 01 0 02 m crack depth 0 3 m resulted in crack closure within 4 5 h starting at the soil surface soil swelling was separated into two components 1 swelling of the 0 01 0 02 m border zone of a soil island soil mass distinctively separated by cracks and 2 swelling of the rest of the soil island as a whole soil swelling was heterogeneous with a very rapid expansion of the border zone at the moment of crack closure the relative contributions of these two components to crack closure were respectively 80 90 and 10 20 24 h later these percentages changed slightly only maximum bulk linear shrinkage determined at the field level was only 7 results indicate the importance of rapid local heterogeneous swelling processes to water flow into cracked vertisol resulting in limited bypass flow use of bulk shrinkage curves and assumptions on isotropy of shrinkage and swelling processes when modelling water and solute flow in cracked vertisols should therefore be done with great care

proprietes caracteristiques des argiles de l est du canada the compilation of numerous geotechnical data has allowed the definition of the main physical mechanical and hydraulic properties of marine and lacustrine clays of eastern canada as well as the establishment of correlations between some of these properties the possible uses of these correlations are described this study shows that the clays of eastern canada exhibit a behaviour similar to that of other clays but that they are characterized by a higher degree of structuration keywords physical properties mechanical properties hydraulic properties clays canada correlations journal translation

structure and seasonal variability of the east sakhalin current abstract in order to clarify the structure and seasonal variability of the flow field near the western boundary of the sea of okhotsk long term mooring measurements were carried out from 1998 to 2000 in this region in most of the mooring period a persistent southward flow the east sakhalin current was observed which extends from the surface to a depth around 1000 m the speed of this southward flow clearly changed seasonally the peak monthly mean speed along 53 n at a depth of 200 m attained a maximum of 37 9 cm s 1 in january and a minimum of 10 8 cm s 1 in july three different cores of intense flow were identified in the southward flow the first core was centered over the continental slope and had rather large vertical extent reaching the bottom on the slope the second core was trapped over the shelf near the surface and was observed from october to november this core was associated with less saline surface water affected by the amur river discharge the third core was intensified toward

a sensitivity study of the dense shelf water formation in the okhotsk sea 1 sensitivity of dense shelf water dsw formation to tidal mixing around the kuril straits wind stress and river runoff in the okhotsk sea is examined by an ice ocean coupled model horizontal resolution of the model is set to 3 8 km in the northern okhotsk sea for well resolving the coastal polynyas which is believed to be the principal region of dsw formation the model shows a good performance in terms of sea ice production and the consequent dsw formation dsw is also found to be formed in the offshore region apart from the coastal polynya dsw is defined independently for each experiment such that it identifies the water influenced by brine by introducing such definition the sensitivity of the dsw formation is assessed separately for change of density and that of formation rate the density of dsw exhibits high sensitivity to all the elements considered herein while its formation rate is sensitive only to winds winds affect the dsw formation rate mainly by influencing that occurs in the offshore region

cracking patterns bypass flow and nitrate leaching in greek irrigated soils abstract bypass flow of water during irrigation by flooding and associated leaching of nitrates were investigated in sixty three 40 cm high undisturbed cores of nineteen calcareous alluvial greek soils cracks conducting bypass water formed a network of polygons on the soil surface the sizes of the polygons increased curvilinearly with clay content large polygons were associated with deeper cracking of the soil mass than the small polygons did the size of the polygons decreased with depth in the profile upon irrigation cracks developed in dry soil were closed by swelling and by soil material falling from their walls the closing was either complete or incomplete the latter leaving a shallow u shaped trace upon drying cracks reformed along the u shaped traces elsewhere cracks developed at new places the volume of bypass water showed a sharp initial decrease with time because of filling of the cracks and swelling but remained significant even after 2 hours the usual irrigation time suggesting that a significant amount of the applied water may move to the subsoil without wetting the surface soil bypass flow showed a marked decrease with increasing initial soil moisture the amounts of nitrate leached by bypass water were rather small ranging from 0 01 to 1 8 of nitrates present in the soil cores

satellite passive microwave studies of the sea of okhotsk ice cover and its relation to oceanic processes 1978 1982 this paper describes the use of the nimbus 7 scanning multichannel microwave radiometer smmr satellite data to study the ice cover in the sea of okhotsk during the four winters of 1978 1982 the ice concentration estimates obtained from smmr are used to study two different polynyas one over the kashevarova bank and the other over the northwest continental shelf for the kashevarova polynya this study shows that the polynya which may be related to the upwelling observed in historic summer cruises occurs directly over the bank for the continental shelf which because of strong offshore winds and cold temperatures is a region of high ice production the polynya areas are combined with heat flux estimates from weather station data to yield the production rates of ice salt and dense shelf water as a previous study by kitani 1973 shows the mixing of this dense shelf water with pacific water yields a water mass unique to the okhotsk which is the layer of cold low salinity intermediate water between depths of 150 and 800 m from our calculations we estimate that the dense shelf water is produced at an annual rate of about 0 5 sv and that the intermediate water is produced at a rate of 1 2 sv which yields a renewal time for this layer of 10 40 years

expansion of the southern california oxygen minimum zone during the early to mid holocene due to reduced ventilation of the northeast pacific abstract oceanic deoxygenation observed since the 1950s has drawn increasing concern as dissolved oxygen do regulates marine biodiversity and biogeochemical cycles yet the do time series from direct instrumental measurements is insufficiently long several decades to constrain the centennial to millennial variability here we present redox sensitive metal re u and mo records from santa barbara basin sbb california to reconstruct subsurface do through the holocene significantly higher authigenic metal fluxes and coherent benthic foraminifera faunal responses along a published depth transect reveal vertical expansion and intensification of the southern california oxygen minimum zone omz prior to 6 ka comparison with post industrial trace metal records suggests low oxygen conditions were more extreme during early to mid holocene mh highlighting the magnitude of omz variability in the absence of anthropogenic influences inconsistencies between authigenic metal fluxes and local oxygen control indicate a remote weakening of the north pacific intermediate water npiw formation prior to the mh reduced ventilation of the mid depth north pacific is supported by state of the art earth system model simulations with realistic mh 6 ka forcing highlighting the importance of brine rejection during sea ice formation in changing the buoyancy of npiw and its basin wide influences on north pacific omz evidence from holocene marine lake records and model simulations further suggests a southward intertropical convergence zone itcz migration and a consequent deepening of the aleutian low al towards late holocene which favors more sea ice brine rejection thus mid depth ventilation in the north pacific was closely associated with atmospheric circulation during the holocene

millennial scale variability of holocene hydrography in the southwestern okhotsk sea diatom evidence diatom analysis of two submarine cores off eastern hokkaido island northern japan provides insights into the holocene palaeoenvironmental history of the southwestern okhotsk sea diatom flora was

depositional and geotechnical properties of marine clays in lianyungang china the mineralogy geochemistry and geotechnical properties of clay samples in lianyungang china are presented the correlations of depositional history depositional environmental and geotechnical properties are discussed a series of x ray diffraction tests show that the principal clay minerals of the soil are illite smectite mixed layer mineral and illite the geochemistry investigation results indicate that the pore water of the lianyungang marine clay is dominant by sodium the ph of the soils varies in the range of 7 8 to 8 9 the depositional environment is oxidation condition the correlations of the geochemistry with the geotechnical properties are examined by the statistic analysis

the origin of the north pacific intermediate water possible source regions of the north pacific intermediate water npiw were investigated with synoptic conductivity temperature depth surveys in the okhotsk sea kuril basin a pycnostad referred to as the okhotsk sea mode water osmw was found in the density range of 26 6 27 the pycnostad is not seen in the western subarctic gyre wsag thus it is an indicative water peculiar to the okhotsk sea the maximum thickness is at 26 7 26 9 centered at 26 8 which coincides with the npiw density range in the north pacific subtropical gyre in the oyashio area east of the southern kuril islands and hokkaido waters that have intermediate temperature salinity and potential vorticity between the osmw and the wsag water were distributed suggesting a following transport route of the npiw source water the thick thus low q q is potential vorticity and low salinity water mass outflowing from the okhotsk sea mixes with the relatively warm saline and high q wsag water to form the oyashio water a coastal part of the oyashio water flows southwestward along the east coast of the southern kuril islands and hokkaido retaining the pycnostad q minimum a large part of the low q oyashio water flows further southward and merges with the kuroshio extension and then flows eastward forming new npiw in this process a salinity minimum develops and the q minimum disappears because of the mixing with a saline kuroshio water old npiw without a pycnostad in the npiw density range these results suggest that the origin of npiw is the water mass in the okhotsk sea osmw and the density of the water mass primarily determines the npiw density centered at around 26 8

effects of along shore wind on dsw formation beneath coastal polynyas application to the sea of okhotsk 1 it is known that salinity anomaly under a polynya reaches and remains an equilibrium value s after termination of its initial increase associated with brine rejection at the surface in this paper we investigate effect of along shore downwelling favorable wind on the equilibrium salinity anomaly by idealized numerical calculations and scale based estimates numerical calculations showed that high saline water beneath polynya is advected downstream by wind driven circulations over the shelf besides baroclinically developed eddies which consequently induces a decrease in s beneath polynya the downwelling favorable wind generates an offshore overturning flow through lower layers referred to as ekman compensation flow ecf which causes a great offshore salinity flux as well as an along shore current we also constructed an equation for estimation of s from the viewpoint of salinity budget over the polynya region in which lateral salinity fluxes caused by ecf along shore wind driven current and baroclinic eddies are scaled the solution s was also verified by a series of numerical calculations furthermore we investigated the effects of along shore wind on dense water generation beneath the okhotsk coastal polynyas we conducted simplified numerical experiments assuming the okhotsk situation in which fs and offshore width b of polynya are predicted by a thermodynamic polynya model with ecmwf meteorological variables the simulated salinity shows a good agreement with the direct measurements the theoretical estimates for s was also applied to two okhotsk polynyas northwestern polynya nwp and northern polynya np in conclusion we found that the along shore wind causes greater salinity decrease in np than in nwp whose variations substantially depend on the aleutian low activity

the movement of water through cores of a dry cracked clay loam grassland topsoil abstract water bypassed the soil matrix through cracks and other large voids when applied to cores of dry cracked clay loam grassland topsoil at rates in excess of 2 2 mm hr 1 the bypassing ratio increased from 0 to 0 55 as the application rate rose from 2 2 to 21 2 mm hr 1 it was estimated that 10 20 of rainfall bypassed the top 0 09 m of a grassland soil at wytham near oxford england during periods of summer soil moisture deficit

thermohaline effects of the seasonal sea ice cover in the sea of okhotsk 1 by using a coupled ice ocean model the seasonal extent of the sea ice cover in the sea of okhotsk was examined the model results show that the sea ice at the ice edge is advected southward along sakhalin island with a mean velocity of 0 31m s into ocean water with temperatures above freezing as a result even in mid winter a large amount of ice melting occurs around the edge it results in temperature decrease in the surface mixed water during the 1993 1994 winter the total volume ratio of ice melting to ice production is estimated at 0 76 the negative latent heat flux from the ice melting is nearly comparable to the total atmospheric heat flux around the ice edge furthermore the meltwater supply to the surface layer is estimated to be approximately 3 5 times the annual amur river inflow thus it is concluded that the ice melting around the extending ice edge is a significant factor for the heat and salt balance between the sea ice and the surface mixed layer and plays an important role in the maintenance of the large seasonal sea ice extent in the sea of okhotsk

effects of tube sampling in soft clay a microstructural insight this paper analyses the effects of tube sampling in soft clay with particular emphasis on the modifications that occur in the clay fabric for tube specimens retrieved using open samplers shelby a

tidally induced diapycnal mixing in the kuril straits and its role in water transformation and transport a three dimensional nonhydrostatic model experiment 1 baroclinic processes generated by the k1 tidal flow around the kuril straits and their role in the linkage between the okhotsk sea and the north pacific are investigated using a three dimensional nonhydrostatic model large amplitude unsteady lee waves are generated around sill tops all along the kuril island chain and induce significant density inversions from the sea surface down to the 27 6 density layer along with this wave breaking a large flow of energy takes place from the swift tidal flow regions to greater depths as a result of the clockwise propagation of both the topographically trapped waves around the islands and the remaining unsteady lee waves such wave generation and energy exchange eventually cause intense diapycnal mixing over the shallow topographic features and near the bottom leading to a maximum diapycnal diffusivity of over 103 cm2 s 1 even in the deep bussol strait which is thought to be the main exit of the okhotsk sea water considerable mixing corresponding to diapycnal diffusivity values of between 10 50 cm2 s 1 occurs vigorous mixing in the shallow regions produces low potential vorticity pv water in the upper layer and high pv water below accordingly pv fronts are formed along the island chain and sustain instabilities that in turn release baroclinic eddies with low core pv values these features are indicated in recent satellite imagery and in situ observations suggesting that the tide is the controlling factor in the formation of fronts observed in the kuril straits tidally induced mean transport across the straits is estimated to reach 26 sv 1 sv 106 m3 s 1 which is much larger than in the barotropic case however most of the exchanged water tends to circulate around the islands due to the effect of bottom topography whereas eddies pinched off from the tidal fronts carry the exchanged water offshore the amount of eddy driven offshore transport away from the islands reaches 14 sv with roughly half being directed to the north pacific this significant offshore transport spreads the effect of the diapycnal mixing taking place in the straits over wider areas of the north pacific and the okhotsk sea for example the pv values generated in the eddies differ by 30 40 from the ambient water on average whereas sea surface salinity within the eddies is 0 1 psu higher than the surroundings corresponding to the density increase of 0 08 thus the eddy transport provides significant pv and salinity fluxes to both the north pacific and the okhotsk sea hence we infer that a combination of tidally driven processes taking place at the passages leads to the formation of eddies that play a central role in water transport and transformation and are an essential aspect of the physical interplay between the okhotsk sea and the north pacific

deglacial variability in okhotsk sea intermediate water ventilation and biogeochemistry implications for north pacific nutrient supply and productivity highlights multi proxy multi site reconstruction of okhotsk sea palaeo productivity and mid depth ventilation changes from 8 to 18 ka link between hinterland river discharge and downstream okhotsk sea intermediate water osiw ventilation nutrient signatures surplus fe si oh 4 export in osiw during bolling allerod to pelagic pacific supported transient nutrient replete conditions subarctic and subtropical pacific gyres disconnected during bolling allerod with restricted osiw flow to lower latitudes deglacial osiw export and mid depth pacific biogeochemistry modulate millennial scale regional co2 source sink conditions the modern north pacific plays a critical role in marine biogeochemical cycles as an oceanic sink of co2 and by bearing some of the most productive and least oxygenated waters of the world ocean the capacity to sequester co2 is limited by efficient nutrient supply to the mixed layer particularly from deeper water masses in the pacific s subarctic and marginal seas the region is in addition only weakly ventilated by north pacific intermediate water npiw which receives its characteristics from okhotsk sea intermediate water osiw here we present reconstructions of intermediate water ventilation and productivity variations in the okhotsk sea that cover the last glacial termination between eight and 18 ka based on a set of high resolution sediment cores from sites directly downstream of osiw formation in a multi proxy approach we use total organic carbon toc chlorin biogenic opal and caco3 concentrations as indicators for biological productivity c n ratios and xrf scanning derived elemental ratios si k and fe k as well as chlorophycean algae counts document changes in amur freshwater and sediment discharge that condition the osiw stable carbon isotopes of epi and shallow endobenthic foraminifera in combination with 14c analyses of benthic and planktic foraminifera imply decreases in osiw oxygenation during deglacial warm phases from c 14 7 to 13 ka bolling allerod and c 11 4 to 9 ka preboreal no concomitant decreases in okhotsk sea benthic planktic ventilation ages are observed in contrast to nearby but southerly locations on the japan continental margin we attribute okhotsk sea mid depth oxygenation decreases in times of enhanced organic matter supply to maxima in remineralization within osiw in line with multi proxy evidence for maxima in primary productivity and supply of organic matter sedimentary c n and fe k ratios indicate more effective entrainment of nutrients into osiw and thus an increased nutrient load of osiw during deglacial warm periods correlation of palynological and sedimentological evidence from our sites with hinterland reference records suggests that millennial scale changes in osiw oxygen and nutrient concentrations were largely influenced by fluvial freshwater runoff maxima from the amur caused by a deglacial northeastward propagation of the east asian summer monsoon that increased precipitation and temperatures in conjunction with melting of permafrost in the amur catchment area we suggest that osiw ventilation minima and the high lateral supply of nutrients and organic matter during the allerod and preboreal are mechanistically linked to concurrent maxima in nutrient utilization and biological productivity in the subpolar northwest pacific in this scenario increased export of nutrients from the okhotsk sea during deglacial warm phases supported subarctic pacific shifts from generally fe limiting conditions to transient nutrient replete regimes through enhanced advection of mid depth nutrient and fe rich osiw into the upper ocean this mechanism may have moderated the role of the subarctic pacific in the deglacial co2 rise on millennial timescales by combining the upwelling of old carbon rich waters with a transient delivery of mid depth derived bio available fe and silicate

causes of the multidecadal scale warming of the intermediate water in the okhotsk sea and western subarctic north pacific abstractcauses of the multidecadal scale warming of the intermediate water in the okhotsk sea and the western subarctic north pacific during 1980 2008 are investigated using an ice ocean coupled model with interannually varying atmospheric forcing a hindcast experiment qualitatively reproduces the warming and decadal fluctuations of the intermediate water that are similar to those of observations the warming is significant along the western part of the okhotsk sea and subarctic frontal region the effects of the thermohaline and wind driven ocean circulation on the warming are evaluated from perturbation experiments on thermohaline turbulent heat and freshwater fluxes and wind causes respectively the thermohaline causes are shown to contribute positively to warming in the okhotsk sea intermediate water osiw the heat budget analysis for the osiw indicates that the warming is related to a decrease in cold and dense shelf water dsw flux which is caused by a decrease in sea ice and surface water

preferential flow paths in a water repellent clay soil with grass cover grass covered heavy basin clay soils in the netherlands appeared to be water repellent water repellency in the top layers of these soils occurred mainly as a coating on the aggregates the variation in soil moisture content over short distances was studied by sampling the soil 10 times during the period august 31 1993 to december 22 1994 each time 35 samples 100 cm3 were taken in close order over a distance of 195 cm at depths of 0 5 10 15 20 25 and 30 35 cm differences between minimum and maximum soil moisture contents were high in all layers sampled occasionally as much as 28 vol when the clay soil is dry a major proportion of the water from precipitation or sprinkler irrigation may flow rapidly through shrinkage cracks to the subsoil bypassing the matrix of the clay peds however preferential flow is not limited to macropore flow irregular wetting patterns are also formed through the small pores of the matrix the relationship between dry bulk density and volumetric water content was found to be positive when the clay soil was relatively dry and negative when it was relatively wet

near surface circulation and tidal currents of the okhotsk sea observed with satellite tracked drifters 1 near surface circulation of the okhotsk sea was observed with argos drifters from august 1999 to february 2000 the drifters clearly revealed the existence of the southward boundary current the east sakhalin current off the east sakhalin this current is strongly controlled by bottom topography and confined to the region shallower than 1000 m the volume transport of this current is estimated to be in the range of 4 9 sv 1 sv 106m3 s 1 with the increase from summer to winter the current appears to consist of two cores one exists near the coast 50 150 m depths with typical speeds of 0 3 0 4 m s 1 and the other exists over the shelf slope 300 900 m depths with typical speeds of 0 2 0 3 m s 1 a part of this southward current continues as far as the southern tip of sakhalin island while another part turns to the east around terpeniya bay 48 n flowing eastward as far as bussol strait most of the drifters that survived in the okhotsk sea went out to the pacific through bussol strait by less than a half year suggesting that bussol strait is the main pathway for the surface water to flow out from the okhotsk sea mesoscale anticyclonic eddies with diameters of 100 200 km are dominant in the kuril basin diurnal shelf waves were identified over the shelf in the northern part of the east sakhalin shelf large amplification of diurnal tidal currents order of 1 0 m s 1 was observed over kashevarov bank along with the residual anticyclonic circulation both diurnal and semidiurnal tidal currents were found to be enhanced in and around bussol strait

a biomarker approach for assessing marine and terrigenous inputs to the sediments of sea of okhotsk for the last 27 000 years abstract a sediment core taken from the sea of okhotsk which is located in the western north pacific rim with an extensive seasonal sea ice cover was investigated for lipid class compounds total organic carbon total nitrogen and 13 c of bulk organic matter to reconstruct changes in sedimentary regimes of marine and terrestrial organic matter over the last 27 kyrs higher molecular weight n alkanes fatty acids and fatty alcohols showed an increase in terrigenous inputs in glacial and to a greater extent in early deglacial periods the enhanced terrestrial input in the deglaciation stages has for the first time been found and never been reported in the open ocean biomarker profiles together with the coarse grain size distribution in nearby sediment cores suggested that sea ice rafting was the main transport mechanism of continental material to the okhotsk sea sediments however the ice rafting inputs have been weakened from 14 kyrs bp to the holocene probably due to a rapid reduction of the sea ice cover and continental shelf erosion profiles of c 37 alkenones phytol and brassicasterol as well as temporal variation in calcium carbonate and organic carbon contents indicated that the marine inputs were enhanced during the deglaciation the enhanced marine inputs were likely caused by an intensification of the primary production induced by a possibly increased nutrient supply from the continental shelves in early deglaciation and by the deglacial retreat of the sea ice cover at 14 kyrs bp this study demonstrates that biomarkers in the marginal marine sediments had recorded changes in the biogeochemical processes in the sea of okhotsk over the last 27 kyrs which may be significantly affected by changes in the okhotsk water exchange processes such as sea ice activity and sea ice transport of terrigenous materials

okhotsk sea ice coverage and kamchatka glaciation over the last 350ka evidence from ice rafted debris and planktonic δ18o high resolution records of ice rafted debris ird and oxygen isotope records spanning an e w trending transect across the okhotsk sea unravel the marine and terrestrial cryogenic history of ne siberia over the last 350 kyr ird predominantly dispersed basin wide by sea ice shows lowest fluxes during interglacial periods implying a reduced and seasonal sea ice coverage highest ird accumulation rates are observed during glacial and deglacial periods with a more extended but highly dynamic ice cover although being rather synchronous ird fluxes are on average higher in the western okhotsk sea than in the eastern part pointing to a persistent but mobile particle supplying sea ice cover even during full glacial conditions presumably less dense in the eastern parts mis 6 is exceptional in this respect asynchronous fluxes of ird which vary spatially reflect rapid paleoclimatic and paleo glaciomarine changes ird accumulation rates were by factor 2 3 higher during mis 6 as compared to the last glacial maximum and the ird depositional center shifted from the western okhotsk sea early mis 6 toward kamchatka late mis 6 synchronous to a distinct change in the ird mineral composition both the characteristic composition of late mis 6 ird originating from the sredinny mountain range of kamchatka and their significantly enhanced accumulation rates refer to intensified iceberg dispersal across the eastern part of the okhotsk sea at 138 ka 135 ka 129 ka and 128 ka bp this scenario affords the presence of extended mountain glaciers protruding down to sea level on the western side of kamchatka anomalously light planktonic stable oxygen isotopes during mis 6 3 termination ii and mis 5 5 5 4 suggest significant freshwater supply related to the westward drainage of kamchatka glaciers the intensified kamchatka glaciation observed during late mis 6 was repeated during mis 3 iceberg discharges into the eastern okhotsk sea are observed at 60 ka 51 ka 42 ka 38 ka 36 ka and 31 ka and may partly correspond to n atlantic heinrich events

radiolarians under the seasonally sea ice covered conditions in the okhotsk sea flux and their implications for paleoceanography abstract four time series sediment traps at two stations and three piston cores from the okhotsk sea were quantitatively examined for coarse sized radiolarian shells 63 m traps were deployed at 300 m and 1550 m at station m4 53 01 n 145 30 e and at 300 m and 700 m at station m6 49 30 n 146 28 e during august 1998 through may 2000 the chronologies of the piston cores were established applying 18 o and paleomagnetic intensity variations they provide records extending back to marine isotope stage mis 5 51 the modern and past changes in radiolarian assemblages are associated with environmental and productivity changes radiolarian fluxes in the sediment traps exhibited significant summer to autumn flux peaks with suppressed values during the winter when sea ice covered the sea surface at the trap sites total radiolarian accumulation rate rar variations in each core tended to correspond to glacial interglacial cycles and increased during the last deglaciation in particular the temporal rar variation in core xp98 pc1 off kamchatka showed a similar trend with the climatic changes expressed by 18 o values during the glacial interglacial cycles for the last 125 kyr regional differences were also apparent rars showed extremely low values during 12 40 kyr and 63 70 kyr in core xp98 pc2 central okhotsk sea indicating the enhanced sea ice impact the sea ice coverage might have continued for a significant part of the year during the intervals since radiolarians did not appear to increase even during the summer to autumn rar variations in core xp98 pc4 off sakhalin showed higher values than xp98 pc2 during mis 2 and 4 thus in eastern sakhalin around site xp98 pc4 sea ice coverage might have been seasonal but not perennial even during mis 2 and 4 among the radiolarian taxa cycladophora davisiana was the most abundant species at the lower traps and in all cores the fluxes of c davisiana at lower traps showed much higher values than those of upper traps and also showed similar temporal patterns with the fluxes of aluminum and terrigenous materials therefore c davisiana fluxes may be associated with terrigenous organic materials increased nutrient supply from the continental shelves presumably transported by seasonal sea ice and released by sea ice melting might be mainly responsible for the high production of c davisiana in the okhotsk sea especially during the last deglaciation

effect of soil microstructure on the compressibility of natural singapore marine clay the effect of soil microstructure on the compressibility of natural singapore marine clay is studied in this paper it was found that natural singapore marine clay can sustain higher void ratio than reconstituted singapore marine clay at the same effective stress in one dimensional compression this difference is most noticeable between yield stress and two times the yield stress this void ratio difference is commonly attributed to soil microstructure and the decrease in this difference at higher stresses is attributed to progressive destructuration as a consequence of progressive destructuration the virgin compression curve is nonlinear and the compression index along the virgin compression range is variable which is only noticeable during the constant rate of strain consolidation test on high quality samples in the absence of high quality samples and constant rate of strain consolidation tests an empirical method is proposed to obtain a first order estimation of a nonlinear virgin compression cur

climatic and oceanological changes in the southwestern part of the sea of okhotsk during the last 94 kyr abstract this paper presents the results of a study on a sediment core obtained from the southwestern part of the sea of okhotsk by analyzing the diatoms in the sediment along with the productivity proxy and ice rafted debris data we reconstructed the regional environmental and climatic changes occurring over last 94 kyr sea ice expansion periods of active ice melting and variations in marine plankton productivity local warming and cooling events occurring in the late pleistocene and holocene periods as well as transgressive regressive fluctuations in the sea level were documented the shift in the relatively warm interglacial conditions to severe glaciation over 34 kyr ago that occurred in the studied area of the sea of okhotsk was reported for the first time the time at which the la perouse strait opened the soya current input began and the establishment of modern hydrological conditions was approximately 5 6 kyr

ice rafted debris ird based sea ice expansion events during the past 100 kyrs in the okhotsk sea abstract ice rafted debris ird from sediment traps surficial sediments and sediment cores were investigated in order to reconstruct the extent history of sea ice cover during the last 100 kyrs in the okhotsk sea the seasonal ird buried into the sediments during and just after sea ice melting in spring consists of silt and sand size terrigenous particles the spatial distribution of ird within surficial sediments clearly corresponds to the extent of sea ice coverage sea ice expanded to a maximum extent during the glacial periods although sea ice cover was not perennial the okhotsk sea sea ice expansion osie events which are recognized by millennial scale abrupt peaks of ird content have occurred 13 times during the past 100 kyrs these events were amplified during the glacial periods a significant modification of the polar atmospheric circulation in the northern hemisphere is a key process in explaining these osie events

water movement and isoproturon behaviour in a drained heavy clay soil 1 preferential flow processes abstract the processes and mechanisms that control pesticide transport from drained heavy clay catchments are being studied at wytham farm oxford university in southern england in the first field season field drain water contained high concentrations of pesticide soil studies demonstrated that the main mechanism for pesticide translocation was by preferential flow processes both over the soil surface and through the soil profile via a macropore system that effectively by passed the soil matrix this macropore system included worm holes shrinkage cracks and cracks resulting from ploughing rainfall events in early winter rapidly created a layer of saturation in the a horizon perched above a b horizon of very low hydraulic conductivity drain flow was initiated when the saturated layer in the a horizon extended into the upper 0 06m of the soil profile thereafter water moved down slope via horizontal macropores possibly through a band of incorporated straw residues these horizontal pathways for water movement connected with the fracture system of the mole drains thus feeding the drains overland flow occurred infrequently during the season

distribution and formation of okhotsk sea intermediate water an analysis of isopycnal climatological data 1 in order to clarify the distribution and formation of okhotsk sea intermediate water osiw an isopycnal climatological data set based on all of the available historical observations is developed and examined the isopycnal maps clearly show that there are two direct ventilation sources for osiw dense shelf water dsw with cold and fresh properties influenced by sea ice formation in the northwest shelf region and forerunner of soya warm current water fscw which has warm and saline properties originating in the japan sea the cold and fresh water extends southward from the northwest shelf to the shelf slope off sakhalin island it suggests that dsw is transported southward by the east sakhalin current the dsw enters the kuril basin and mixes with fscw and western subarctic water wsaw originating from the north pacific to form osiw the annual mean production rate of dsw estimated from the total volume of dsw over the shelf in spring and summer is 0 67 sv 1 sv 106 m3 s the annual mean volume transport of fscw is estimated to be 0 08 sv on the basis of its cross section area and the current speed assumption of isopycnal mixing yields a mixing ratio of 1 1 0 1 among dsw wsaw and fscw to form osiw we estimate the annual production rate of osiw to be 1 4 sv the corresponding osiw s renewal time is 7 years continued assumption of isopycnal mixing yields a mixing ratio of 0 6 0 4 between wsaw and osiw to form oyashio intermediate water oyiw

disturbance of the bothkennar clay prior to laboratory testing interpretation of laboratory tests in the characterization study of the bothkennar clay required an assessment to be made of the effects of disturbance prior to testing disturbance is shown to have occurred as a result of tube sampling sample transport and specimen preparation the effects of disturbance in the clay are to reduce the mean effective stress in the sample and shrink the initial bounding surface the consequences of these changes are illustrated for the case of unconsoli dated undrained triaxial tests undrained triaxial compression and extension tests after reconsolidation to in situ stress and oedometer tests reduction in peak strength stiffness yield stress and post yield compressibility are shown to be a consequence of disturbance the evaluation of sample quality on the basis of strains during reconsolidation is examined l interpretation des essais de laboratoire dans l etude de caracterisation de l argile de bothkennar necessita l evaluation des effets du remaniement avant essai

effective stress paths and yielding in soft clays below embankments current methods of predicting the response of soft clays to surface loading are often unsuccessful because the assumed constitutive relationships including effective stress path behaviour are incorrect in particular the transition from small strain to large strain behaviour i e yielding is frequently not taken into account recent laboratory testing has demonstrated that the behaviour of soft clays is largely controlled by yielding the locus of effective stress states causing yield is known as the yield envelope ye the effective stress paths esp s in soft clay foundations below the centre of six fills were determined from computed total stresses and measured pore water pressures yield behaviour is clearly indicated by esp shapes the yield envelopes inferred from analyses of field data are similar to those obtained from laboratory testing effective stress path shapes vary widely depending on a variety of factors including imposed stress level rate of construction and boundary drainage co