spatial and temporal variation of geochemical properties and paleoceanographic implications in the south korea plateau east sea during the late quaternary geochemical opal total organic carbon toc and caco3 analyses of three sediment cores from the south korea plateau in the east sea japan sea revealed that the late quaternary 190 kyr bp to the present paleoceanographic conditions are characterized by the orbital variations of geochemical properties that have recorded the changes of surface and bottom water conditions chronostratigraphy of the sediment cores was accomplished by the direct correlation of l values to the well dated core md01 2407 in oki ridge supplement to the ams 14c dates well known lithostratigraphic and tephrostratigraphic markers biogenic opal concentrations are high during marine isotope stage mis 1 and mis 5 5 and low during the glacial period suggesting that diatom production was enhanced during the warm period when the surface water exchange between the east sea and adjacent marginal seas was active in contrast glacial opal paleoproductivity appears to have been depressed probably because of insufficient nutrient availability resulting from limited vertical ventilation overall toc contents follow the orbital variations high during the interglacial and relatively low during the glacial time however high resolution toc fluctuations are independent of opal concentration which may be attributed more to the preservation of organic matter rather than to the surface water production the high toc contents in the thin dark mud i e tl layers may be due to the enhanced surface water production as well as the intensified bottom water anoxia on the other hand high caco3 contents associated with the tl layers during the glacial and stadial period may be attributed to the reduced dissolution the temporal variations of these geochemical properties are likely to follow the global orbital cycles indicating the significant changes of surface and bottom water properties due to the eustatic sea level fluctuations between the interglacial and glacial period the comparable values of these geochemical properties among the sediment cores suggest that the spatial paleoceanographic conditions in the south korea plateau were consistent and uniform during the late quaternary in spite of a little local discrepancy in amounts of properties and timing of events

a study on the regulation of the concentrations of some trace metals rb sr zn pb cu v cr ni mn and mo in saanich inlet sediments british columbia canada abstract bulk metal concentrations were measured in the sediments of saanich inlet in an attempt to establish the occurrence of trace metal enrichment in the anoxic central basin ba ni v cr zn pb cu and mo were found to be enriched in the anoxic ooze over the possible contributions from lithogenic sources spatial and seasonal variations in the chemical composition of the settling particulates collected with interceptor traps gave further indications of the mode of incorporation of these metals biogenic ba and cr appeared to be associated with opaline silica although alternative explanations are also possible particularly for ba zinc seemed to be added to the sediment essentially in association with planktonic materials while cu required an additional source directly linked to the anoxic environment similarly ni v and mo were added to the anoxic sediments by reactions occurring at the sediment water interface in the nearshore environment studied here these metals particularly ni and mo were not associated to any significant extent with planktonic materials of all the elements analyzed mo showed the largest enrichment in the anoxic sediments of saanich inlet

origins and paleoceanographic significance of laminated muds from the ulleung basin east sea sea of japan abstract a detailed facies analysis of long piston core sediments from the ulleung basin reveals four mud facies laminated mud crudely laminated mud bioturbated mud and homogenous mud the laminated and homogeneous muds were most likely deposited from turbidity currents whereas the bioturbated and crudely laminated muds were formed by hemipelagic pelagic sedimentation under well oxygenated and poorly oxygenated bottom water conditions respectively a detailed analysis of vertical distribution of the mud facies together with a chronostratigraphic framework derived from correlative tephra layers with known eruption ages reveals paleoenvironmental changes during the late quaternary during the period between 49 and 23 ka eustatic lowering of sea level facilitated frequent slope failure resulting in repeated deposition of fine grained turbidites on the basin floor normal hemipelagic sediments were intensively bioturbated under well oxygenated bottom water conditions during the period between 23 and 13 to 11 ka deposition from turbidity currents continued but hemipelagic sediments were non bioturbated under poorly oxygenated bottom water conditions the bottom water deoxygenation is attributed to further lowering of sea level during the last glacial period and consequent intensified stratification in the water column by freshwater supply to the nearly isolated sea primary laminae preserved in the crudely laminated mud generally exhibit low compositional bimodality in backscattered electron images which suggests low surface primary productivity and presence of superficial micro bioturbation after rapid rise of sea level at 13 to 11 ka the slopes were stabilized and pelagic sedimentation has prevailed under well oxygenated bottom water conditions

geochemistry of surface sediments in the southwestern east japan sea abstract we analyzed 77 surface sediment samples collected in the southwestern east japan sea from the korea strait through the ulleung basin and the korea plateau for grain size calcium carbonate organic carbon and major na mg al fe k ca and ti and trace elements p mn sr li sc v cr co ni zn cu and pb the chemical composition of the surface sediments was found to be highly variable spatially cluster analysis of surface sediment chemical compositions indicated five major geochemical sedimentary environments basin lower slope coast and upper slope inner shelf and outer shelf continental shelf sediments were rich in shell fragments and had relict and coarse grained characteristics recent fine grained sediments were only distributed in coastal slope and basin areas concentrations of al k ca ti cr and sc were highest in the coastal and upper slope areas and decreased with water depth elemental ratios using major and trace elements indicated that coastal and upper slope detrital sediments were mixtures of sediments derived from the changjiang yangtze and nakdong rivers although the concentrations of organic carbon p mn v co ni cu and pb increased with water depth their distribution patterns indicated authigenic v cu and pb and diagenetic fe p mn co and ni origins the distribution pattern with water depth suggested that the chemical composition of surface sediment was determined by sedimentologic and geochemical processes such as the supply of detrital and biogenic materials and authigenic and post depositional diagenetic processes in sediments

the benthic cycle of copper evidence from sediment trap experiments in the eastern tropical north pacific ocean abstract the benthic fluxes of 24 elements and components are calculated from sediment trap fluxes and sediment accumulation rates at manop sites h and m in the eastern tropical north pacific ocean in this paper we focus our discussion on our data for copper benthic flux estimates for copper are 0 7 and 1 4 nmol cm 2 yr at h and m respectively these results compare well with estimates from another trap deployment in the galapagos and modeling of pprewater and water column concentration data by other authors partitioning of near bottom cu flux indicates that the two sites receive similar amounts of primary cu flux flux from upper water column and resuspended cu flux only the site located on the east pacific rise site m shows any input of hydrothermal cu at site m 35 of the near bottom flux is due to some source other than primary resuspended or hydrothermal flux we speculate that dissolved cu from the sediments is readsorbed onto particles near the bottom at this site sequential leaching of trap material indicates that the flux of cu associated with organic matter using an operational definition ranges from 56 to 84 of the trap material this fraction of the total cu increases with depth in the water column probably through scavenging

minor elements in quaternary sediment from the sea of japan a record of surface water productivity and intermediate water redox conditions sediment of quaternary age from oki ridge 903 m depth in the sea of japan 3500 m deep records six episodes of high accumulation rates of cd cr cu mo ni u v and zn the high rates correspond to periods of sulfate reduction in the water column at the intermediate depth of oki ridge the intervening low values correspond to periods of denitrification and oxygen respiration the maxima have a period of 41 k y the youngest having an age of 1 10 ma the 41 k y cycle is similar to the cycle of 18 o values of open ocean plankton of the same age the similarity between the cycles of minor element accumulation in sea of japan sediment and 18 o values of atlantic ocean foraminifera indicates that redox changes in the water column of the sea of japan during the quaternary forced by major shifts in water column advection and minor shifts in photic zone productivity reflect global events

the inorganic geochemistry of cretaceous black shales dsdp leg 41 in comparison to modern upwelling sediments from the gulf of california

reconstruction of environmental changes using a multi proxy approach in the ulleung basin sea of japan over the last 48 ka based on elemental geochemical data we reconstructed the sediment provenance surface productivity and bottom water redox conditions for the last 48 ka in the ulleung basin sea of japan and inferred the factors controlling them al2o3 tio2 ratio and chemical index of alteration cia suggest that sediment provenance changed during the glacial period 48 18 ka compared to the deglacial ca 18 11 ka and holocene mass accumulation rates of total organic carbon toc caco3 phosphorus cadmium and excess barium reveal low paleoproductivity during low sea stand during 18 11 ka productivity increased due to increasing inflow of nutrient rich water masses the oyashio and the east china sea coastal water in tandem with the rising sea level maximum productivity occurred during younger dryas and pre boreal periods when sea level was at 60 m and then gradually decreased as the tsushima warm current inflow kicked off at ca 9 3 ka consistent with other paleoredox proxies which reveal the presence of anoxic bottom water during ca 12 9 ka with the changes in paleoredox proxies and their ratios toc mo u mn c s ratio and uauthigenic and mo contents we hypothesized that the redox changes were mainly ventilation driven and were superimposed on the influence of circulation induced productivity changes the global climate and sea level changes on a millennial timescale play a major role in enhancing paleoproductivity and restrict bottom water advection subsequently driving the oxygenation of bottom water in the ulleung basin copyright 2012 john wiley sons ltd

the contrasting biogeochemistry of iron and manganese in the pacific ocean abstract vertical and horizontal distributions of dissolved and suspended particulate fe and mn and vertical fluxes of these metals obtained with sediment traps were determined throughout the pacific ocean in general dissolved fe is low in surface and deep waters 0 1 to 0 7 nmol kg with maxima associated with the intermediate depth oxygen minimum zone 2 0 to 6 6 nmol kg vertical distributions of dissolved mn are similar to previous reports exhibiting a surface maximum a subsurface minimum a mn maximum layer coincident with the oxygen minimum zone and lowest values in deep waters near shore removal processes are more intense for dissolved fe than for dissolved mn dissolved mn in the surface mixed layer remains elevated much farther offshore than dissolved fe elevated near surface dissolved mn concentrations occur in the north pacific equatorial current suggesting transport from the eastern boundary near surface mixed layer dissolved mn concentrations are higher in the north pacific gyre reflecting enhanced northern hemisphere aeolian sources residence time estimates for the settling of refractory paniculate fe and mn from the upper water column are 62 220 days fe and 105 235 days mn in contrast residence times for the scavenging of dissolved fe and mn are 2 13 years fe and 3 74 years mn scavenging residence times for dissolved mn based on horizontal mixing in the surface mixed layer of the northeast pacific are 0 4 years nearshore to 19 years 1000 km offshore there is no evidence for in situ fe redox dissolution within sub oxic waters in the eastern tropical north pacific dissolved fe appeared to be controlled by dissolution from sub oxic sediments with oxidative scavenging in the water column or upper sediment layers however in situ mn dissolution within the oxygen minimum zone was evident

paleoenvironmental changes in the japan sea during the last 85 000 years five distinct changes in the paleoenvironment of the japan sea within the last 85 000 years are revealed from the sedimentary record of a piston core recovered from the oki ridge changes in both surface and deepwater conditions are registered by changes in lithology calcium carbonate content organic carbon content oxygen and carbon isotope ratios and microfossil assemblages including calcareous nannoplankton diatoms radiolaria and foraminifera between 85 and 27 ka the warm tsushima current did not flow into the japan sea and cold surface water conditions prevailed environments at the seafloor fluctuated between dysaerobic to weakly oxic conditions between 27 and 20 ka freshwater input to the japan sea probably from the huang ho river in china stratified the water column and the severe anoxic conditions eliminated most benthic fauna between 20 and 10 ka the cold oyashio current flowed into the japan sea through the tsugaru strait reestablishing deepwater ventilation shallow water benthic assemblages of the north pacific ocean subsequently colonized the japan sea and occupied the vacant niches of the deep basins between 10 and 8 ka the foraminifer compensation level fcl gradually rose to a depth shallower than 1000 m and bottom conditions changed from dysaerobic to oxic at 10 ka the warm tsushima current started to flow into the japan sea through the tsushima strait to establish the modern oceanographic regime which has existed since 8 ka the eustatic sea level during the last glacial maximum was above the sill depths 130 m of the tsushima and tsugaru straits assuming that tectonic movements at these straits were negligible for the last 20 ka

the planar shape of drumlins abstract the asymmetry of the planar shape of drumlins is an established paradigm in the literature and characterizes drumlins as resembling tear drops with a blunt bullet shaped stoss end and a tapering pointed lee end it is widely cited and never been seriously questioned in this paper the planar shape of 44 500 drumlins mapped in various regional settings from drumlin fields in north america and northern europe were objectively analysed by means of geographic information system tools two parameters were considered the first denoted here as as pl focuses on the relative position of the point of intersection between the axes of the maximum length and the maximum width it is defined as the distance between the upstream i e beginning of the drumlin and the intersection point measured along the longitudinal axis divided by the entire length of the long axis results indicate that the intersection point of the majority of drumlins 64 is very close to the longitudinal midpoint 0 33 as pl as pl a is defined as the ratio between the area of the upstream half of the drumlin to that of the entire drumlin results show that for most drumlins 81 the upper half area is almost as large as the down half 0 45 as pl a

pleistocene deep sea ostracods from the oki ridge sea of japan iodp site u1426 and condition of the intermediate water the sea of japan also termed the east sea has a circulation system isolated from the pacific ocean and east china sea the east asian winter monsoon drives the circulation system and cools the tsushima warm current twc to form the japan sea intermediate proper water jsipw the intermediate water conveys oxygen to deep sea floors which is available for benthic animals during the pliocene 3 5 2 8 ma temperate intermediate water tiw was formed under the weak winter monsoon and extinct ostracod tiw taxa were found little is known about early pleistocene intermediate water and the extinction mode of benthic ostracods we studied radiolarians and ostracods from deep sea sediments between 2 0 and 1 3 ma marine oxygen isotope stage mis 77 to mis 41 at integrated ocean drilling program site u1426 sea of japan the ostracod faunas contained tiw and jsipw taxa the radiolarian subtropical water taxa and the jsipw ostracods indicate a small influx of the twc and the jsipw the tiw occasionally expanded to the middle bathyal zone by analogy with the relationship between the modern jsipw and winter monsoon weak winter monsoon possibly caused gentle temperature gradients in the water column and the expansion of the tiw the jsipw taxa expanded their ranges into the deep sea during interglacial periods

global variations of surface ocean productivity in low and mid latitudes influence on co2 reservoirs of the deep ocean and atmosphere during the last 21 000 years based on detailed reconstructions of global distribution patterns both paleoproductivity and the benthic 13c record of co2 which is dissolved in the deep ocean strongly differed between the last glacial maximum and the holocene with the onset of termination i about 15 000 years ago the new export production of low and mid latitude upwelling cells started to decline by more than 2 4 gt carbon year this reduction is regarded as a main factor leading to both the simultaneous rise in atmospheric co2 as recorded in ice cores and with a slight delay of more than 1000 years to a large scale gradual co2 depletion of the deep ocean by about 650 gt c this estimate is based on an average increase in benthic 13c by 0 4 0 5 the decrease in new production also matches a clear 13c depletion of organic matter possibly recording an end of extreme nutrient utilization in upwelling cells as shown by sarnthein et al 1987 the productivity reversal appears to be triggered by a rapid reduction in the strength of meridional trades which in turn was linked via a shrinking extent of sea ice to a massive increase in high latitude insolation i e to orbital forcing as primary cause

molybdenum in the northeast pacific ocean1 the concentration of dissolved molybdenum has been determined in several profiles from the northeast pacific ocean the salinity normalized concentration is essentially constant in all open ocean samples 107 nm 1 2 5 nm the dissolved distribution is not significantly affected by biological cycling

controls on trace metal authigenic enrichment in reducing sediments insights from modern oxygen deficient settings any effort to reconstruct earth history using variations in authigenic enrichments of redox sensitive and biogeochemically important trace metals must rest on a fundamental understanding of their modern oceanic and sedimentary geochemistry further unravelling the multiple controls on sedimentary enrichments requires a multi element approach of the range of metals studied most is known about the behavior of fe mn and mo in this study we compare the authigenic enrichment patterns of these elements with a group whose behavior is not as well defined cd cu zn and ni in three oxygen poor settings the black sea the cariaco basin venezuela and the peru margin these three settings span a range of biogeochemical environments allowing us to isolate the different controls on sedimentary enrichment our approach relying on the covariation of elemental enrichment factors ef defined for element x as efx x al sample x al lithogenic has previously been applied to mo and u to elucidate paleoenvironmental information on for example benthic redox conditions the particulate shuttle and the evolution of water mass chemistry we find two key controls on trace metal enrichment first the concentration of an element in the lithogenic background sediment used in calculating efx controls the magnitude of potential enrichment maximum enrichment factors of 376 and 800 are calculated for mo 1 ppm in detrital sediments and cd 0 3 ppm respectively compared to values not greater than 17 in any setting for the other five metals 45 ppm to 4 5 wt in detrital sediments second there is a relationship between the aqueous concentration of the element in overlying seawater and its degree of enrichment in the sediment we further identify four important processes for delivery of trace metals to the sediment these are 1 cellular uptake especially important for zn and cd 2 interaction co precipitation with sulfide mo cu and cd 3 passive scavenging via the traditional particulate shuttle mo ni and cu and 4 an association with the benthic fe redox shuttle mn ni finally we summarize the oceanic mass balance of cd and mo and place the first constraints on the contribution of reducing sediments to the oceanic mass balance of cu zn and ni we show that reducing sediments are the ultimate repository for up to half the total output flux of these elements from the oceanic dissolved pool

tracking the onset of phanerozoic style redox sensitive trace metal enrichments new results from basal ediacaran post glacial strata in nw canada abstract a global rise in oxygen levels has been proposed to coincide with the ediacaran to cambrian radiation of animals yet the precise timing and nature of this change remains unresolved one hypothesis is that the ocean atmosphere system became temporarily well oxygenated in the earliest ediacaran directly following the marinoan snowball earth glaciation 635 ma the evidence for oxygenation is based on large enrichments of redox sensitive trace elements in black shale from south china presumably deposited under a euxinic water column these enrichments meet or exceed the bulk concentrations of redox sensitive trace elements found in phanerozoic shale deposited under euxinic water columns here we test the early ediacaran post snowball oxygenation hypothesis with new data from a high resolution multi proxy geochemical and sedimentological study of three stratigraphic sections in the earliest ediacaran sheepbed formation of the mackenzie and wernecke mountains nw canada iron speciation data from all sections suggest that the local water column was dominantly ferruginous with a notable exception of probable euxinic conditions recorded in part of one section redox sensitive elements show no appreciable enrichments in the basal sheepbed formation with maximum concentrations of molybdenum vanadium uranium and chromium only slightly above world average shale values the lack of substantial elemental enrichments within the sheepbed formation is consistent with results from coeval ferruginous strata in svalbard the dominance of local ferruginous conditions in nw canada cannot alone account for the muted redox sensitive element enrichments as v u and cr are thought to be enriched under these conditions and samples deposited under euxinic conditions also lack phanerozoic style enrichments these contrasting results from different localities highlight a need to further investigate the veracity of trace metal enrichments in all localities as representing global redox conditions as the results have important implications for the timing of oxygenation with respect to early animal evolution

measurement and parameterization of aerodynamic roughness length variations at haut glacier d arolla switzerland spatial and temporal variations in aerodynamic roughness length z0 on haut glacier d arolla switzerland during the 1993 and 1994 ablation seasons are described based on measure ments of surface microtopography the validity of the microtopographic z0 measurements is established through comparison with independent vertical wind profile z0 measurements over melting snow slush and ice the z0 variations are explained through correlation and regression analyses using independent measurements of meteorological and surface variables and parameterizations are developed to calculate z0 variations for use in surface energy balance melt models several independent variables successfully explain snow z0 variation through their correlation with increasing surface roughness caused by ablation hollow formation during snow melt non linear parameterizations based on either accumulated melt or accumulated daily maximum temperatures since the most recent snowfall explain over 80 of snow z0 variation the z0 following a fresh snowfall on an ice surface is parameterized based on relationships with the underlying ice z0 snow depth and accumulated daily maximum temperatures none of the independent variables were able to successfully explain ice z0 variation although further comparative studies are needed the results lend strong support to the microtopo graphic technique of measuring z0 over melting glacier surfaces

rare earth elements in foraminifera tests abstract the concentrations of nine rare earth elements ree la ce nd sm eu gd dy er and yb have been determined in mixed species assemblages of foraminifera tests taken from atlantic ocean sediment core tops reductive cleaning techniques have revealed that ree are present in three phases in foraminifera tests collected from sea floor sediments ree included in the foraminiferal calcite matrix termed lattice ree ree associated with an authigenic femn rich phase adsorbed onto the surface of the test following the death of the organism termed coating ree and ree associated with alumino silicate detritus termed detrital ree which commonly infills the test chambers after burial in the sediment the concentrations of ree in the nondetrital lattice plus coating and lattice phases have been measured in this study approximately 90 of the ree measured in the non detrital phase reside in the coating phase the remainder being present in the lattice phase these data have been used to investigate the relationship between the distribution of dissolved ree in the ocean and in the coating and lattice phases in addition to the ree the concentrations of mn fe cu al and po4 have been measured as an aid to characterisation of the various phases

seawater as the source of minor elements in black shales phosphorites and other sedimentary rocks many of the minor elements in seawater today have a concentration depth profile similar to that of the biologically essential nutrients no 3 and po3 4 they show a relative depletion in the photic zone and enrichment in the deep ocean the difference between their surface and deep ocean values normalized to the change in po3 4 approaches the average of measured minor element p ratios in marine plankton although individual analyses of the latter show extreme scatter for a variety of reasons despite this scatter in the minor element analyses of plankton agreement between the two sets of data shows unequivocally that an important marine flux of many minor elements through the ocean is in the form of biogenic matter with a composition approaching that of plankton this interpretation is further supported by sediment studies particularly of sediments which accumulate in shelf slope environments where biological productivity in the photic zone is exceptionally high and organic carbon contents of the underlying sediment elevated the interelement relations observed for some of these sediments approach the average values of plankton these same interelement relations are observed in many marine sedimentary rocks such as metalliferous black shales and phosphorites rocks which have a high content of marine fractions e g organic matter apatite biogenic silica and carbonates many previous studies of the geochemistry of these rocks have concluded that local hydrothermal activity and or seawater with an elemental content different from that of the modern ocean was required to account for their minor element contents however the similarity in several of the minor element ratios in many of these formations to minor element ratios in modern plankton demonstrates that these sedimentary rocks accumulated in environments whose marine chemistry was virtually identical to that seen on continental shelf slopes or in marginal seas of the ocean today the accumulation of the marine fraction of minor elements on these ancient sea floors was determined largely by the accumulation of organic matter settling from the photic zone and with a composition of average plankton a second marine fraction of minor elements in these rocks accumulated through precipitation and adsorption from seawater the suite of elements in this fraction reflects redox conditions in the bottom water as determined by bacterial respiration for example high mn high cr v and high mo concentrations above those which can be attributed to the accumulation of planktonic matter characterize accumulation under bottom water oxidizing denitrifying and sulfate reducing conditions respectively

instability of bottom water redox conditions during accumulation of quaternary sediment in the japan sea the concentrations of cd cr cu mo ni sb u v and zn were measured in early quaternary sediment 1 32 to 1 08 ma from the oki ridge in the japan sea the elements were partitioned between a detrital fraction composed of terrigenous and volcaniclastic aluminosilicate debris and a marine fraction composed of biogenic and hydrogenous debris derived from seawater the most important factors controlling minor element accumulation rates in the marine fraction were 1 primary productivity in the photic zone which largely controlled the flux of particulate organic matter bound minor elements settling through the water column and onto the seafloor and 2 bottom water redox which determined the suite of elements that accumulated directly from seawater this marine fraction of minor elements on oki ridge recorded six periods of high minor element abundance assuming a constant bulk sediment accumulation rate each period lasted roughly 5 000 to 10 000 years with a 41 000 year cycle accumulation rates of individual elements such as cd mo and u suggest sulfate reducing conditions were established in the bottom water during the 10 000 year periods accumulation rates of cr and v during the intervening periods are indicative of less reducing denitrifying conditions interelement ratios for example cu mo v cr and sb mo further reflect bottom water instability such that bottom water redox actually varied from sulfate reducing to denitrifying during the periods of highest minor element accumulation rates it varied from denitrifying to oxidizing during the intervening periods sediment lithology supports these interpretations of the minor element distributions the sediment is finely laminated for several of the periods represented by cd mo and u maxima and weakly laminated to bioturbated for the intervening periods the geochemistry of this sediment demonstrates the unambiguous signal of mo principally but of several other minor elements as well in recording sulfate reducing conditions in bottom water the forcing function that altered their accumulation that is that altered primary productivity and bottom water redox conditions is problematic currently held opinion suggests that o2 depletion was most strongly developed during glacial advances low sea level during such times is interpreted to have enhanced primary productivity and restricted bottom water advection

a high resolution late quaternary upwelling record from the anoxic cariaco basin venezuela results are presented of a high resolution study of the planktonic foraminiferal faunas from two piston cores recovered from the cariaco basin in the southern caribbean sea the cariaco basin is a small anoxic marine basin on the northern continental margin of venezuela in an area today characterized by both seasonal trade wind induced upwelling and pronounced dry and wet seasons our data indicate that large changes in the intensity of upwelling and hence trade wind strength occurred in this region during the last glacial interglacial transition and throughout the holocene during the last glacial lowstand of sea level the cariaco basin was effectively isolated from the open caribbean along its northern margin by the then largely emergent tortuga bank oxic conditions existed in the deep cariaco basin at this time and surface productivity was low about 12 600 years ago the abrupt initiation of strong upwelling over the basin and the onset of permanent anoxia in the deep waters are coincident with the rapid rise of sea level that accompanied the peak interval of meltwater discharge from the laurentide ice sheet into the gulf of mexico strong upwelling between 12 600 and about 10 000 years ago may be related to intensified trade winds resulting in part from cooler sea surface temperatures in the caribbean and gulf of mexico after about 10 000 years ago upwelling intensity was reduced though highly variable a preliminary frequency domain analysis of the holocene portion of the cariaco basin time series suggests that solar forcing may explain a significant component of the century scale variability observed in the record of upwelling and trade wind strength

coupling between suboxic condition in sediments of the western bay of bengal and southwest monsoon intensification a geochemical study abstract reconstruction of paleo redox conditions in a radiocarbon 14c dated sediment core sk 218 1 covering the past 45 ka thousand calendar years collected from the western bay of bengal lat 14 02 n long 82 00 e at a water depth of 3307 m has been made based on redox sensitive element geochemistry the high u th ratio mo enrichment mo u enrichment factor ratio ce ce we also provide the first record of the nitrogen isotopic composition 15n of sedimentary organic matter in the western bay of bengal a region where the mesopelagic oxygen minimum zone omz is just short of being suboxic denitrifying today the sedimentary 15n fluctuated considerably in the past especially during the marine isotope stage 3 oscillations in 15n were apparently in concert with those in organic carbon and nitrogen contents and could be related to climatic changes heinrich and dansgaard oeschger events in the north atlantic the dansgaard oeschger 12 event appears to have exerted the most intense effect on bay of bengal biogeochemistry when surface productivity as inferred from the organic carbon and nitrogen contents was the highest recorded in the core and the 15n reached up to 6 3 considering the probable dilution by isotopically light terrigenous organic matter it would appear that omz of the bay of bengal had turned denitrifying however the absence of suboxic conditions in the sediments at this time suggests a decoupling of the benthic processes with those in the mesopelagic water column

concentration oxidation state and particulate flux of uranium in the black sea abstract in contrast to its unreactive behavior in the open ocean uranium is removed from seawater to sediments of anoxic marine basins four biogeochemical processes have been proposed to account for this removal active uptake by organisms whose remains are preserved by the anoxic conditions of the sediments complexation of u vi by particulate organic matter chemical reduction of soluble u vi to insoluble u iv which is scavenged to the sediments by settling particles and precipitation of uranium within the sediments themselves the black sea is the largest anoxic marine basin in the world today waters below 150 200 m are anoxic and h2s levels build up to about 400 mol 1 1 in the bottom water maximum depth 2200 m concentrations of total u and the oxidation state of dissolved u were measured throughout the water column while particulate u fluxes were determined from time series sediment trap samples collected in the deep anoxic zone bottom waters were depleted in u by 40 relative to the initial u content of the water two independent methods gave residence times of dissolved u in the deep water column of about 103 years uranium occurred throughout the water column as soluble chemically labile reducible u vi rather than the thermodynamically favored u iv uranium is neither reduced to u iv by the high levels of h2s nor is it rapidly scavenged from the water column as would be expected for strongly hydrolyzed tetravalent actinides like u iv fluxes of particulate authigenic u measured with sediment traps are at least two orders of magnitude less than the rate of authigenic u burial in black sea sediments therefore the first three processes listed above contribute negligibly to the deposition of u in the sediments of anoxic marine basins such as the black sea the dominant removal process must involve precipitation of u in the sediments rather than scavenging from the water column

evidence for solar forcing on the indian monsoon during the last millennium abstract solar influence on the intensity of the indian monsoon is demonstrated using a sediment core from the eastern arabian sea dating back to 1200 yr through pattern matching as well as spectral analysis of proxy records of monsoon and solar activity the intensity of the indian monsoon is found to have decreased during periods of solar minima during the last millennium periodicities of 200 20 105 15 and 60 10 yr are observed in the proxy records coinciding with those known for solar cycles the 60 yr periodicity observed in the instrumental rainfall data appears to be of solar origin and supports the hypothesis of solar control on the indian monsoon on a multi decadal time scale evidence for the presence of a coupled atmospheric forcing for the indian and east african monsoons on a centennial time scale is also seen

analysis of a 3 year meteorological record from the ablation zone of morteratschgletscher switzerland energy and mass balance since 1 october 1995 an automatic weather station has been operated on the tongue of morteratschgletscher switzerland the station stands freely on the ice and sinks with the melting glacier surface it is located at 2100 m a s l and measures air temperature wind speed and direction incoming and reflected solar radiation pressure and snow temperature a sonic ranger mounted to stakes drilled into the ice measures surface height from which melt rates and snow accumulation can be derived in this paper the data for the period 1 october 1995 to 30 september 1998 are used to evaluate the surface energy balance the turbulent energy fluxes are calculated with the bulk method the turbulent exchange coefficient c h is used as a control parameter with c h 0 00127 the calculated melt equals the observed melt which is 17 70 m w e over the 3 years when averaged over the time when melting occurs i e 35 of the time the mean surface heat flux equals 191 w m 2 net shortwave radiation contributes 177 w m 2 net longwave radiation 25 w m 2 the sensible heat flux 31 w m 2 and the latent heat flux 8 w m 2

aerodynamic stability and turbulent sensible heat flux over a melting ice surface the greenland ice sheet the turbulent sensible heat flux to a melting ice surface is calculated from wind speed and air temperature at 2 m over the ice surface assuming a certain wind profile with the appropriate surface roughness the aerodynamic stability of the boundary layer over melting ice is examined by comparing sensible heat fluxes for logarithmic and log linear wind profiles where the logarithmic profile is strictly valid only for neutral conditions increasing stability reduces the sensible heat flux to the glacier surface and introduces a non linear relation between heat flux and air temperature the stability effect is greatest at low wind speeds and fairly small at the high wind speeds that are common over the ice sheet earlier estimates of ablation by energy balance modelling may be too large due to neglect of stability but this was almost offset by using a surface roughness that was too small the log linear wind profile should be used in future energy balance models to take account of stability but more research is needed on the parameters of the profile as well as on the surface roughness

chronostratigraphy and paleoceanography of a piston core ebp 3 from the south korea plateau in the east sea japan sea abstract a piston core ebp 3 collected from the south korea plateau in the east sea japan sea preserved typical alternations of thick dark laminated mud layers and bioturbated hemipelagic mud layers but included several intercalated volcanic lapilli layers the age estimate of core ebp 3 was aided by correlation of biostratigraphic radiolarian data the abundance of microfossils warm water radiolarians and geochemical properties caco 3 with the proxies of the well dated core md01 2407 obtained from the oki ridge a part from the marine isotope stage mis 11 to mis 9 in the middle of core ebp 3 was missing presumably because of erosion following the abrupt deposition of a volcanic lapilli layer despite some uncertainty the age estimate of core ebp 3 revealed that the lower part of core ebp 3 represents mis 13 as was also evident from a comparison with the oxygen isotope stratigraphy downcore biogenic opal and caco 3 variations in core ebp 3 exhibited less distinct orbital scale cyclic changes than cores from other areas in the east sea japan sea however differences in features were discernible between mis 2 and mis 12 in terms of their lithology and caco 3 constituent although both periods were characterized by relatively high levels of caco 3 about 30 for mis 2 and about 50 for mis 12 mis 2 preserved a typical thick dark laminated mud layer whereas mis 12 preserved a distinctly light mud layer with thin parallel laminations this difference of the lithologic facies between mis 2 and mis 12 highlighted a discrepancy among the major constituents indicating that planktonic foraminifera were dominant in mis 2 whereas coccolithophores were dominant in mis 12 our results suggest that the thinly laminated light mud layer which is characterized by a high caco 3 content primarily composed of coccolithophores in mis 12 can be used as a reliable time marker for the establishment of chronostratigraphy in the east sea

geochemistry of suspended particles in the subantarctic and polar frontal zones south of australia constraints on export and advection processes filtered particles from a southern ocean meridional transect from 42 s to 54 s along 142 e off tasmania were studied between surface and 600 m water depth saz 1998 expedition february april 1998 particulate ba sr ca p u th ti al mn light rare earth elements and zr contents were analyzed by inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectroscopy mesopelagic baxs total ba minus a lithogenic fraction estimated from al contents were higher within the polar front zone pfz in comparison with the northern areas indicating that c export to the intermediate and deep ocean is more important in the pfz average surface uxs versus latitude covaries with mesopelagic baxs contrasting with organic matter proxies such as pp and chlorophyll a this similar behavior suggests that u might be preferentially adsorbed on organic material which subsequently becomes involved with barite precipitation srp and cap contents decrease sharply with depth following total particle content for the northern area 42 47 s surface ce anomaly reflects essentially a lithogenic signature 0 6 ce ce 1 ascribed to the supply from the tasmanian continental shelf suspended matter from surface waters at stations south of 47 s shows an enhanced seawater signature 0 3 ce ce 0 6 in all stations ce anomalies increase with depth toward values close to 1 this is likely due to the increase of lithogenic authigenic ratio of particles with depth rather than redox processes finally an advective event is identified at 45 s below 200 m by a strong increase of lithogenic element contents which affects baxs

uranium in foraminiferal calcite as a recorder of seawater uranium concentrations abstract we present results of an investigation of uranium calcium ratios in cleaned foraminiferal calcite as a recorder of seawater uranium concentrations for accurate reconstruction of past seawater uranium content shell calcite must incorporate uranium in proportion to seawater concentration and must preserve its original uranium composition over time laboratory culture experiments with live benthic amphistegina lobifera and live planktonic globigerinella calida foraminifera show that the u ca ratio of cleaned calcite tests is proportional to the concentration of uranium in solution after correcting results for the presence of initial calcite the apparent distribution coefficient d u ca calcite u ca solution 10 6 0 3 10 3 for a lobifera and d 7 9 0 1 10 3 for g calida u ca ratios in planktonic foraminifera from core tops collected above 3900 m in the equatorial atlantic and above 2100 m in the pacific ocean show no significant difference among the species analyzed d estimated from core top samples ranges from 7 6 0 4 10 3 for o universa to 8 4 0 5 10 3 for g ruber in benthic species c wuellerstorfi d 7 0 0 8 10 3 u ca and mg ca in g tumida and g sacculifer from core tops taken near and below the regional lysocline decrease with water depth smaller decreases in u ca and mg ca with depth were observed in c wuellerstorfi in the planktonic species we believe that u ca and mg ca are lower in the more dissolution resistant fraction of calcite leading to lower u ca in more highly dissolved samples

rare earth element geochemistry of oceanic ferromanganese nodules and associated sediments abstract analyses have been made of ree contents of a well characterized suite of deep sea 4000 m principally todorokite bearing ferromanganese nodules and associated sediments from the pacific ocean ree in nodules and their sediments are closely related nodules with the largest positive ce anomalies are found on sediments with the smallest negative ce anomalies in contrast nodules with the highest contents of other rare earths 3 ree are found on sediments with the lowest 3 ree contents and vice versa 143 nd 144 nd ratios in the nodules 0 51244 point to an original seawater source but an identical ratio for sediments in combination with the ree patterns suggests that diagenetic reactions may transfer elements into the nodules analysis of biogenic phases shows that the direct contribution of plankton and carbonate and siliceous skeletal materials to ree contents of nodules and sediments is negligible inter element relationships and leaching tests suggest that ree contents are controlled by a p rich phase with a ree pattern similar to that for biogenous apatite and an fe rich phase with a pattern the mirror image of that for sea water it is proposed that 3 ree concentrations are controlled by the surface chemistry of these phases during diagenetic reactions which vary with sediment accumulation rate processes which favour the enrichment of transition metals in equatorial pacific nodules favour the depletion of 3 ree in nodules and enrichment of 3 ree in associated sediments in contrast ce appears to be added both to nodules and sediments directly from seawater and is not involved in diagenetic reactions

are drumlins a product of a thermo mechanical instability abstract of numerous theories of drumlin genesis none has been widely accepted it seems evident however that some form of positive feedback process is involved under certain circumstances perturbations are amplified herein we suggest that patchy areas of frozen bed provide the initial perturbation such frozen patches may occur in local areas underlain by material of lower thermal conductivity or on slight topographic highs drag exerted by the frozen patch deflects ice flow into its lee dragging with it mobile till eroded from the thawed area the energy balance is such that this till likely refreezes either producing a topographic perturbation or amplifying an existing one the resulting topography then deflects more of the geothermal heat away from the developing hill and into the adjacent trough resulting in a positive feedback once the thermal perturbation exceeds a critical though as yet undefined level melting may decouple the ice from the bed preventing further entrainment of till from thawed areas and thus limiting the height and length of the drumlin

dissolved sulfide distributions in the water column and sediment pore waters of the santa barbara basin dissolved sulfide concentrations in the water column and in sediment pore waters were measured by square wave voltammetry nanomolar detection limit during three cruises to the santa barbara basin in february 1995 november december 1995 and april 1997 in the water column sulfide concentrations measured outside the basin averaged 3 1 nm n 28 in the 0 to 600 m depth range inside the basin dissolved sulfides increased to reach values of up to 15 nm at depths 400 m a suite of box cores and multicores collected at four sites along the northeastern flank of the basin showed considerable range in surficial 400 m at 10 cm decreases in water column nitrate below the sill depth indicate nitrate consumption 55 to 137 mole m 2 h 1 similar to nearby santa monica basin peaks in pore water iron concentrations were generally observed between 2 and 5 cm depth with shallowest peaks at the 590 m site these observations including observations of the benthic microfauna suggest that the extent to which the sulfide flux sustained by elevated pore water concentrations reaches the water column may be modulated by the abundance of sulfide oxidizing bacteria in addition to iron redox and precipitation reactions

compositions and transport of lipid biomarkers through the water column and surficial sediments of the equatorial pacific ocean abstract a systematic investigation of fluxes and compositions of lipids through the water column and into sediments was conducted along the u s jgofs egpac transect from l2 n to l5 s at 140 w fluxes of lipids out of the euphotic zone varied spatially and temporally ranging from 0 20 0 6 mmol lipid c m 2 day 1 lipid fluxes were greatly attenuated with increasing water column depth dropping to 0 002 0 06 mmol lipid c m 2 day 1 in deep water sediment traps sediment accumulation rates for lipids were 0 0002 0 00003 mmol lipid c m 2 day 1 lipids comprised 11 23 of corg in net plankton 10 30 in particles exiting the euphotic zone 2 4 particles in the deep egpac and 0 1 1 in sediments lipids were in general selectively lost due to their greater reactivity relative to bulk organic matter toward biogeochemical degradation in the water column and sediment qualitative changes in lipid compositions through the water column and into sediments are consistent with the reactive nature of lipids fatty acids were the most labile compounds with polyunsaturated fatty acids pufas being quickly lost from particles branchedchain c15 and c17 fatty acids increased in relative abundance as particulate matter sank and was incorporated into the sediment indicating inputs of organic matter from bacteria long chain c39 alkenones of marine origin and long chain c20 c30 fatty acids alcohols and hydrocarbons derived from land plants were selectively preserved in sediments compositional changes over time and space demonstrate the dynamic range of reactivities among individual biomarker compounds and hence of organic matter as a whole a thorough understanding of biogeochemical reprocessing of organic matter in the oceanic water column and sediments is thus essential for using the sediment record for reconstructing past oceanic environments

trace elemental derived paleoceanographic and paleoclimatic conditions for pleistocene eastern mediterranean sapropels abstract eastern mediterranean sediments are characterized by cyclic deposition of organic rich sediments known as sapropels enhanced primary productivity combined with bottom water oxygen depletion are thought to be the main drivers for sapropel deposition we selected sapropel layers from a suite of odp leg 160 cores and applied a set of geochemical proxies to determine paleo productivity variations redox conditions of the water column during deposition and provenance of detrital material high sedimentary ba al and corg contents indicate enhanced primary production whereas the sedimentary la lu ratio points to an enhanced contribution from a north african riverine source during sapropel formation these features are especially pronounced on sapropels s5 and s7 deposited during a particularly warm climatic interval this indicates a more intense north african drainage weathering and consequently run off for those sapropels that have the most enhanced expression of productivity too correspondingly the latter has also resulted in bottom water redox conditions that have been more severe during these sapropels than during others deepwater formation from adriatic and aegean areas thought to be mainly controlled by sustained cooling of preconditioned surface waters triggers the onset of bottomwater ventilation thus sapropel duration our data therefore suggest that the intensity of sapropel formation is determined by the north african monsoonal system whereas their duration is directed by northern borderlands climatic conditions