continental inputs of beryllium to the oceans abstract an understanding of the geochemistry of the cosmogenic radioisotope 10 be t 1 2 1 5 my and the stable isotope 9 be is necessary for the development of their use in deep sea sediments as a geochronometer and as a monitor of variations in cosmogenic nuclide production we examined these isotopes in oceanic regions strongly influenced by input of continental materials the effects of atmospheric aerosols were studied through examination of the water column chemistry of the mediterranean a basin strongly influenced by saharan dust while salinity transects through the amazon and ganges brahmaputra estuaries were used to investigate riverine fluxes to the oceans these results were used to quantify riverine and eolian fluxes they indicate that eolian dust is probably the most significant source of 9 be to the oceans changes in 10 be 9 be in the marine sedimentary record which are not associated with radioactive decay or variability in 10 be production can thus result from local or regional changes in dust inputs

five million year10be record in chinese loess and red clay climate and weathering relationships 10be measurements in bulk samples in different size fractions in selective chemically leached fractions of several representative loess paleosol sequences and in the underlying red clay sediments from the chinese loess plateau back to ca 5 ma were made using the ams accelerator mass spectrometer our data support but considerably extend the earlier studies of shen and beer and their colleagues in the upper 0 75 ma luochuan loess paleosol sequences the effect of climatic change is dramatically expressed by10be concentrations 1 in the red clay sediments for which we estimate model accumulation rates of 5 8 and 8 7 m ma 1 for the upper sequences in lingtai and baoji respectively 2 in the paleosols where soil maturation processes are manifest in the10be distribution within different size fractions accompanied by downward movement to zones of high authigenic mineral concentration and 3 in loess samples which at deposition had an appreciable endowment of10be from the dust source regions on the basis of leaching experiments we estimate that on average the paleosol layers lost about 3 3 of their initial10be content to the underlying layers by transport with water finally we estimate that the relative average zonal precipitation rate during glacial periods was 2 3 the average interglacial value the estimates of the initial10be concentrations and dust composition are consistent with the measured values for the recent atmospheric dust falls sampled from the loess plateau and the shandong peninsula

chronostratigraphy of odp 181 site 1121 sediment core southwest pacific ocean using 10be 9be dating of entrapped ferromanganese nodules a 10be 9be based chronostratigraphy has been determined for odp 181 site 1121 sediment core recovered from the foot of the campbell plateau southwest pacific ocean this core was drilled through the campbell skin drift in ca 4500 m water depth on the mid western margin of the extensive campbell nodule field beneath the flow of the major cold water deep western boundary current dwbc in the absence of detailed biostratigraphy beryllium isotopes have provided essential time information to allow palaeo environmental interpretation to be undertaken on the upper 7 m of the core measured 10be 9be ratios of sediment and of ferromanganese nodules entrapped in the sediment decrease systematically with depth in the core in accordance with radioactive decay however the 10be 9be data diverge from ca 3 m below the seafloor mbsf to the top of the core giving rise to several possible geochronological models the preferred model assumes that the measured 10be 9be ratios of the nodule rims reflect initial 10be 9be ratios equivalent to contemporary seawater and that these can be used to derive the true age of the sediment where the nodules occur the nodule rim ages can be then used to interpret the sediment 10be 9be data which indicate an overall age to ca 7 mbsf of ca 17 5 ma the derived chronology is consistent with diatom biostratigraphy which indicates an age of 2 2 3 6 ma at 1 mbsf calculated sedimentation rates range from 8 to 95 cm m y 1 with an overall rate to 7 mbsf of ca 39 cm m y 1 the lowest rates generally coincide with the occurrence of entrapped nodules and reflect periods of increased bottom current flow causing net sediment loss growth rates of individual nodules decrease towards the top of the sediment core similar to the observed decrease in growth rate from core to rim of seafloor nodules from the campbell nodule field this may be related to an overall increase in the vigour of the dwbc from ca 10 ma to the present

growth rate variations of manganese nodules and crusts induced by paleoceanographic events time markers at about 3 ma 6 5 ma and 14 ma are common to 16 manganese nodules and crusts from different localities in the world oceans these time markers correspond to variations in the growth rates in the inner structure and in the chemistry of the samples the observed time markers could be related to 1 changes of the bottom water velocity and 2 variations in the manganese and iron contents in the deep ocean the time markers were determined by high resolution 10be dating applying the accelerator mass spectrometry facility at the eidgenossische technische hochschule zurich

beryllium 10 in hydrothermal vent deposits from the east pacific ridges role of sediments in the hydrothermal processes beryllium 10 concentrations were determined for 31 handpicked hydrothermal sulfides six oxyhydroxides seven basalts and five sediments collected from the hydrothermally active areas of the east pacific ridges the samples include specimens from the east pacific rise epr at 21 n and 13 n the galapagos rift the guaymas basin and the gorda and the juan de fuca ridges additional samples from massive sulfides associated with the oman ophiolites were studied in all samples we obtained values ranging from 0 04 106 atoms g to 125 106 atoms g with the lowest values being very close to our blank 0 015 106 atoms g the data show systematic variations with sample location and type the 10be concentrations measured for the mid ocean basalts are of the order of 0 3 10 atoms g and reach 3800 106 atoms g for the pelagic deep sea sediments collected near the epr 21 n based on their 10be concentrations we can clearly distinguish two categories of sulfides sulfides containing low 10be concentration 106 atoms g located atop of a thick pile of young sediments guaymas basin or gorda ridge the oxy hydroxides collected on some of the juan de fuca chimneys are always very rich in 10be with concentrations reaching 125 106 atoms g we propose three mechanisms to explain these data 1 mechanical entrapment of sediments in the hydrothermal chimneys as observed in the gorda ridge sulfides 2 leaching of 10be from the ocean crust sediments transport by hydrothermal fluids and coprecipitation with heavy metals as hypothesized to explain the be concentrations observed in the guaymas basin and 3 passive adsorption of 10be from seawater preferred hypothesis oxy hydroxides of the areas with no sediment cover

boundary scavenging in the pacific ocean a comparison of 10be and 231pa concentrations of u th 231pa and 10be were measured in holocene sediments from two cores collected off the west coast of south america two cores from the east pacific rise two from the equatorial pacific and one from the south pacific central gyre our results together with data from 5 cores reported in the literature show that boundary scavenging plays a major role in the removal of 10be from the pacific ocean deposition rates of 10be at three margin sites are more than an order of magnitude greater than at sites of red clay accumulation in the deep central pacific deposition of 231pa is 4 to 5 fold greater at the margin sites the residence time of 10be with respect to chemical scavenging defined as its inventory in the water column divided by its rate of removal to the sediments varies regionally from 1000 years at the red clay sites in the deep central pacific to 100 years at the margin sites different factors control boundary scavenging of pa and be for example scavenging of 231pa is enhanced by metal oxide coatings of particles whereas this seems to have little influence on the scavenging of 10be 1990

application of cosmogenic 10be to dating soils on the raised coral reef terraces of kikai island southwest japan 10be concentrations of six soils on the raised coral reef terraces of kikai island southwest japan range from 0 80 to 7 17 109 atoms g 1 the annual deposition rate of 10be from the atmosphere to kikai island from 2000 to 2002 ranges from 2 0 to 3 5 106 atoms cm 2 year 1 with a mean of 2 8 0 7 106 atoms cm 2 year 1 minimum absolute ages calculated from the inventory of meteoric 10be in the soils and the annual deposition rate of 10be are initial rendzina like soil 8 ka rendzina like soil 18 ka brown rendzina like soil 56 ka terra fusca like soil 127 ka terra rossa like soil 136 ka and intergrade between terra rossa like and red yellow soil 102 ka therefore it was concluded that soil formation during the first 60 000 years would be as rendzina like soils and more than 100 000 years would be required for red yellow soils to develop on raised coral reef terraces under subtropical humid climatic conditions

quasi conservative behaviour of 10be in deep waters of the weddell sea and the atlantic sector of the antarctic circumpolar current we present the first transect of dissolved 10be depth profiles across the antarctic circumpolar current acc in the atlantic sector north of the polar front the 10be concentrations increase continuously from very low values at the surface to values of up to 1600 atoms g at depth deep water 10be concentrations of particular water masses are consistent with earlier results obtained further north south of the polar front and in the weddell sea the distribution of 10be is also characterised by low surface concentrations but below 1000 m depth the concentrations are relatively constant and significantly higher up to 2000 atoms g than further north probably as a result of mixing and advection of water masses of pacific origin overall the deep water 10be distribution is obviously not significantly affected by scavenging processes or ice melt and comparison with the density distribution suggests that 10be can be viewed as a quasi conservative tracer this provides a tool for an improved understanding of the behaviour of other more particle reactive trace metals in the southern ocean such as 230th in deep waters north of the acc weddell gyre boundary awb 10be 230th has a relatively constant value 1 7 0 3 109 atoms dpm over a wide density range whereas south of the awb the ratio is significantly lower 1 1 0 2 109 atoms dpm this normalisation to 10be corroborates that 230th is enriched by 50 due to accumulation south of the awb as a consequence of minimal particulate fluxes the quasi conservative behaviour deduced from our results also implies that 10be can only be used as a tracer for southern ocean particle fluxes in the past if ocean circulation patterns and water mass residence times did not change significantly

highly resolved beryllium 10 record from odp site 1089 a global signal abstract in this study a highly resolved beryllium 10 record from a rapidly accumulating sediment core located in the southern cape basin odp leg 177 site 1089 is presented to extract the global 10 be production signal from the sedimentary record a dedicated correction procedure is applied first sediment redistribution is quantified by applying thorium 230 normalization then lateral transport of 10 be and 230 th is assessed using simple box model calculations the model results indicate that only minor transport corrections have to be applied thus site 1089 combines the advantage of good time resolution with nearly negligible oceanic transport of 10 be leading to a favored site for the reconstruction of global 10 be production changes from marine sediments our results suggest that the transport corrected 10 be record at site 1089 reflects long term variations of the global 10 be production rate over the past 300 kyr the absolute values of the youngest holocene samples are in good agreement with the estimated recent long term averaged global 10 be production rate deduced from observations the variability of the 10 be flux over the past 300 kyr corresponds well to the expected range deduced from model calculations the comparison with other reconstructions of geomagnetic paleointensity and with records of cosmogenic nuclides further emphasizes the global character of this 10 be record therefore our results show that it is possible to quantitatively extract the global 10 be production rate from a single marine record if transport processes are corrected for since the error of a single reconstruction is large a combination of several highly resolved and transport corrected 10 be records may lead to a significantly improved reconstruction of geomagnetic variability and of global cosmic ray flux and over the past 300 kyr

preliminary estimates of regolith generation and mobility in the susquehanna shale hills critical zone observatory pennsylvania using meteoric 10be abstract this study seeks to quantify the rate and timing of regolith generation in the critical zone at the susquehanna shale hills critical zone observatory ssho meteoric 10 be depth profiles were determined using measurements from 30 hillslope soil and bedrock core samples in an effort to constrain 10 be inventories the ssho is located in the temperate climate zone of central pennsylvania and comprises a first order watershed developed entirely on a fe rich organic poor silurian aged shale two major perturbations to the landscape have occurred at ssho in the geologically recent past including significant and sustained periglacial activity until after the retreat of the laurentide ice sheet 21 ka and deforestation during early colonial land use bulk soil samples n 16 were collected at three locations along a planar hillslope on the southern ridge of the catchment representing the ridge top mid slope and valley floor rock chip samples n 14 were also collected from a 24 m deep core drilled into the northern ridge top all meteoric 10 be concentration profiles show a declining trend with depth with most of the 10 be retained in the uppermost decimeters of the soil meteoric 10 be inventories are higher at the mid slope and valley floor sample sites at 3 71 0 02 10 10 at cm 2 and 3 69 0 02 10 10 at cm 2 than at the ridge top site 1 90 0 01 10 10 at cm 2 the 10 be inventory at the convex ridge top site implies a minimum residence time of 10 6 ka or if erosion is steady an erosion rate of 19 4 0 2 m my

revealing sediment sources mixing and transport during erosional crater evolution in the hyperarid negev desert israel abstract to better understand the sedimentary history of the erosional crater of makhtesh hazera in the hyper arid negev desert of southern israel we have measured concentrations of in situ 10 be in alluvial sediments from the active drainage system and from abandoned alluvial terraces and dated them using optically stimulated luminescence osl these sedimentary sequences suggest changes in the drainage system behavior over time and show a periodic pattern in which periods of sediment aggradation alternate with periods of degradation through incision and erosion in alluvial terrace sediments 10 be concentrations were combined with osl ages to gain insight of the temporal framework of sediment deposition and shed light on the process of sediment storage osl and simple 10 be exposure ages of terrace sediments give deposition ages between 340 ka to 50 ka at which time the youngest alluvial terrace was incised deposition was interrupted twice at 300 ka and 160 ka when periods of rapid incision caused the abandonment of the active fluvial surface and the stabilization of a younger and lower fluvial surface in the active drainage system 10 be concentrations suggest several possible quartz sources of which the lower cretaceous sandstone bedrock exposed at the base of the cliff enclosing the makhtesh is the most dominant the results suggest that sediment eroding form these cliffs are conveyed through the active alluvial channels without significant sediment contribution from alluvial terraces or from eroded bedrock exposed within the makhtesh in contrast to our measurements in the active drainage system 10 be concentrations in alluvial terrace sediments record significant storage within the makhtesh we suggest that the geometry of the makhtesh mainly the disproportion between the size of the makhtesh and its narrow outlet leads to significant accumulation of sediment within the makhtesh episodic breaching of the barrier is followed by rapid and short lived incision into the stored sediment the long residence time of sediment within the makhtesh results in high measured 10 be concentrations at the end of each of these short incision episodes when channels are already carved into the alluvial sediment and terraces are formed the channels only convey sediment directly eroded from the bounding cliff of the makhtesh a situation presently observed

the global average production rate of10be precipitation collected in continuously open containers for about a year at seven sites around the united states was analyzed for10be 90sr 210pb and238u based on these data and long term precipitation 90sr and210pb delivery patterns the stratospheric tropospheric and recycled10be components in the collections were estimated and the global10be production rate was assessed single station production rate estimates range from 0 52 106 atoms cm 2 yr 1 to 2 64 106 atoms cm 2 yr 1 the mean value is 1 21 106 atoms cm 2 yr 1 with a standard error of 0 26 106 atoms cm 2 yr 1

recycling of cosmogenic nuclides after their removal from the atmosphere special case of appreciable transport of 10be to polar regions by aeolian dust abstract in this paper we discuss the general problem of recirculation of atmospheric cosmogenic isotopes after their initial removal from the atmosphere practically all nuclides are recycled after their removal from the atmosphere the noble gas radio nuclides re circulate between the atmosphere and the hydrosphere the fraction of time spent in these reservoirs depends on their solubility and half lives radiocarbon atoms spend most of their life time in the oceans before being removed to the sediments all cosmogenic nuclides which are removed from the atmosphere by wet precipitations spend most of their life time in the hydrosphere or in sediments a special exception arises in the case of nuclides such as 10 be and 26 al which are particle active and adhere to aerosols and top soils in the lithosphere strong winds dislodge surface particles and transport the smaller particles to great distances we discuss the special case of the transport of particle reactive 10 be via aeolian dust which can result in appreciable 10 be fluxes in polar regions in cold climates vis a vis its direct deposition from the atmosphere we compare estimated concentrations of dust transported 10 be with the measured total 10 be concentrations in antarctica in the vostok and taylor dome ice cores and atmospheric 10 be concentrations in greenland in the gisp and grip ice cores during certain epochs high aeolian dust concentrations contribute significantly to 10 be fluxes in greenland comparable to or greater than atmospheric 10 be fluxes in the antarctica however even during epochs of high dust fluxes the aeolian 10 be contributions are 10 be fluxes these results imply that great care should be taken in analyzing 10 be concentrations in greenland especially

beryllium 10 thorium 230 and protactinium 231 in galapagos microplate sediments implications of hydrothermal activity and paleoproductivity changes during the last 100 000 years biogenic particle fluxes from highly productive surface waters boundary scavenging and hydrothermal activity are the main factors influencing the deposition of radionuclides in the area of the galapagos microplate eastern equatorial pacific in order to evaluate the importance of these three processes throughout the last 100 kyr concentrations of the radionuclides 10be 230th and 231pa and of mn and fe were measured at high resolution in sediment samples from two gravity cores klh 068 and klh 093 high biological productivity in the surface waters overlying the investigated area has led to 10be and 231pa fluxes exceeding production during at least the last 30 kyr and probably the last 100 kyr however during periods of high productivity at the up welling centers off peru and extension of the equatorial high productivity zone a relative loss of 10be and 231pa may have occurred in these sediment cores because of boundary scavenging the effects of hydrothermal activity were investigated by comparing the 230thex concentrations to the mn fe ratios and by comparing the fluxes of 230th and 10be which exceed production the results suggest an enhanced hydrothermal influence during isotope stages 4 and 5 and to a lesser extent during isotope stage 1 in core klh 093 during isotope stages 2 and 3 the hydrothermal supply of mn was deposited elsewhere probably because of changes in current regime or deep water oxygenation a strong increase of the mn fe ratio at the beginning of climatic stage 1 which is not accompanied by an increase of the 230thex concentration is interpreted to be an effect of mn remobilization and reprecipitation in the sediment

the origin of10be in island arc volcanic rocks the presence of cosmogenic10be t1 2 1 5 106 y in island arc volcanic rocks has been interpreted as indicating that sediments are subducted to the depths of island arc magma genesis 1 2 we have measured10be and9be the stable common isotope in phenocryst and groundmass fractions separated from four aleutian volcanic rocks 10be and9be covary linearly in three of the rocks proving that the10be was incorporated prior to the formation of phenocrysts in the other rock10be and9be do not covary the lack of covariation indicates either that the rock incorporated10be during weathering or that9be rich xenocrysts were incorporated by mechanical mixing our results strongly support the hypothesis of brown et al 1 and tera et al 2 that sediments containing10be are an integral part of island arc magmatic systems as we cannot identify the depth at which the10be was incorporated we still cannot completely rule out the possibility of assimilation of sediments or altered crust near the earth s surface as a source of10be

examination of hydrothermal influences on oceanic beryllium using fluids plume particles and sediments from the tag hydrothermal field we have carried out a comprehensive study of the distributions of9be and the cosmogenic radionuclide10be in fluids nearfield sediments and neutrally buoyant plume particles associated with the tag hydrothermal field these results coupled with previously published uranium decay series radionuclide distributions 1 2 suggest that the level of mno2 in iron oxide rich sediments and particles may play a role in be scavenging in addition the data are used to quantify the net effects of nearfield coprecipitation with fes and of scavenging by iron oxyhydroxide plume particles on the oceanic balance of the be isotopes these calculations suggest that hydrothermal input of9be is nearly balanced by nearfield and plume removal processes and that hydrothermally induced scavenging has a negligible effect on the oceanic10be budget

geochemical and isotopic studies of bauxitization in the tatun volcanic area northern taiwan the tatun volcanic area in the northern tip of taiwan is composed of pleistocene andesite and andesitic tuff its high relief causes extraordinarily heavy rainfall 3000 mm yr 1 especially during the winter monsoon season bauxite deposits were formed on the windward northern slopes soil samples from two profiles in the bauxite deposits were studied by chemical analysis x ray diffraction differential thermal analysis and hydrogen and oxygen isotopic analyses the soil profiles can be divided into two zones by chemical characteristics in the upper zone zone a the chemical composition of the soil samples undergoes little change except depletion of na and ca due to leaching the major minerals are quartz chlorite and illite in the lower zone zone b all major elements suffer rapid dissolution except al2o3 gibbsite grows drastically at the expense of clays while quartz diminishes sharply fe2o3 and tio2 are enriched at the boundary between the two zones due to coprecipitation of fe and ti as hematite and goethite probably as a result of increasing oxygen fugacity mobilization of fe in zone b is attributed to its low eh thus zone a is inferred as a permeable layer and zone b as an aquifer the weathering rate in this area is estimated to be 12 cm ka 1 the most thoroughly leached soil samples contain up to 80 gibbsite the high gibbsite contents and the analyses of coexisting waters allow hydrogen and oxygen isotopic fractionation factors between gibbsite and water to be calculated as 0 992 0 002 and 1 016 0 001 respectively

beryllium geochemistry in soils evaluation of 10be 9be ratios in authigenic minerals as a basis for age models soils contain a diverse and complex set of chemicals and minerals being an open system both in the chemical and nuclear sense soils have defied quantitative nuclear dating however based on the published studies of the cosmogenic atmospheric 10be in soils its relatively long half life 1 5 ma and the fact that 10be gets quickly incorporated in most soil minerals this radionuclide appears to be potentially the most useful for soil dating we therefore studied the natural variations in the specific activities of 10be with respect to the isotope 9be in mineral phases in eight profiles of diverse soils from temperate to tropical climatic regimes and evaluated the implications of the data for determining the time of formation of soil minerals following an earlier suggestion lal et al 1991 development of cosmogenic nuclear methods for the study of soil erosion and formation rates current sci 61 636 639 we find that the 10be 9be ratios in both bulk soils and in the authigenic mineral phases are confined within a narrower range than in 10be concentrations also the highest 10be 9be ratios in authigenic minerals are observed at the soil rock interface as predicted by the model we present model 10be 9be ages of the b horizon and the corresponding soil formation rates for several soil profiles the present study demonstrates that the 10be 9be ratios in the authigenic phases e g clay and fe hydroxides can indeed be used for obtaining useful model ages for soils younger than 10 15 ma however the present work has to be pushed considerably further to take into account more realistic age models in which for instance downward transport 10be and clays and in situ dissolution of clay minerals at depths altering the 10be 9be ratios of the acidic solutions are included we show that in the case of younger soils 1 ma studied here their 10be inventories and 10be 9be ratios have been significantly disturbed possibly by mixing with transported soils

distribution of10be and9be in the pacific ocean abstract the vertical distributions of10be and9be at three locations in the pacific 25 n 170 e 17 n 118 w 3 s 117 w are presented the results show that both isotopes exhibit nutrient like profiles from the surface to the bottom the increase for10be is two to threefold and that for9be is about fivefold while the inter station variations in surface water concentrations may reach a factor of two deep water values tend to be much more uniform averaging about 2000 atoms g for10be and 30 pm for9be a similar situation applies to the10be 9be ratio it varies approximately from 1 to 3 10 7 atom atom at shallow depths but tends toward a value close to 1 1 10 7 in the deep ocean the variation of10be 9be can be viewed as resulting from the fact that10be in a given parcel of water consists of two components recycled and primary the recycled component is that part of10be which has reached tracer equilibrium with9be as opposed to the primary component which upon entering the sea from the atmosphere has yet to equilibrate with9be through particle cycling and mixing processes it is estimated that 70 to nearly 100 of10be at the three stations are being recycled and the recycled beryllium bears an atomic ratio of10be 9be close to 1 10 7 the oceanic residence time of be is of the order of 1000 4000 years comparable to or slightly longer than the ocean mixing time

constraints on deep water formation from the oceanic distributions of 10be 1 an analysis of the oceanic distribution of cosmogenic 10be shows that deep waters are formed by descending of cold dense surface waters at a rate of 18 sv 106 m3 s 1 in the northern north atlantic and 21 sv of which 17 sv enters the pacific in the antarctic over the last mixing cycle of 800 years lending support to the estimates based on radiocarbon and nutrient distributions it also indicates that deep water production in the northern north atlantic is 50 higher averaging over the recent 100 years than over the last mixing cycle suggesting a possible increase in the thermohaline ventilation of the north atlantic during the past century

the fallout rate of pb 210 on the western coast of the united states the deposition rate of atmospheric pb 210 has been measured during a one year period using plastic funnels as collectors observed rates were 0 15 dmp cm sup 2 yr sup 1 at a site in palo alto california and 0 21 dpm cm sup 2 yr sup 1 at a site in los angeles the palo alto value agrees well with a long term average of 0 14 dpm cm sup 2 yr sup 1 obtained from a nearby salt marsh core these rates are only one third of those previouslyl estimated using global models for pb 210 fallout and indicate the need to consider both longitude and precipitation as factors controlling fallout rates more than 75 of the pb 210 fallout occurs as wet deposition at the los angeles site

beryllium 10 in continental sediments abstract the concentration of 10 be has been measured in 10 samples taken from a transect of surface sediments beginning in the atchafalaya river and extending across the bay 136 km into the gulf of mexico if corrected for a lower retentivity of sand for be they have a concentration that is constant within 13 this concentration is about an order of magnitude smaller than that of deep ocean sediments for comparison measurements of 10 be in rainwater in a sample of soil and in a deep ocean core were made

be isotopes in rivers estuaries and their oceanic budgets 10be and 9be have been determined in several north american rivers and in the estuaries of san francisco bay and the pearl river china the average fluvial concentration of dissolved 10be in the rivers is 3220 1960 1 atoms g almost an order of magnitude higher than the observed estuarine values and slightly higher than the 10be concentration in the ocean 1700 atoms g for dissolved 9be a similar order of magnitude drop in concentration also occurs in going from rivers 750 740 pm to estuaries 80 140 pm however in contrast to the 10be situation there appears another order of magnitude drop from estuaries to the ocean which has 9be concentrations of 5 30 pm in spite of the wide range of concentrations for both isotopes in river and estuarine waters 10be 9be ratios range mostly from 2 to 12 10 9 with a median value of 7 10 9 atom atom and are much lower than the seawater ratio of 10 7 in the rivers studied a given volume of water contains roughly equal amounts of particulate and dissolved 10be the 10be concentration in particulate matter ranges from 2 106 to 1 109 atoms g particulate with a median value of about 5 107 atoms g particulate a two box model calculation shows that coastal regions play an important role in the removal of be isotopes from the ocean and that eolian dusts may be the chief source of oceanic 9be because of the marginal removal effect the overall oceanic residence time of be should be shorter than the residence time of 500 1200 yr estimated for the open ocean

10be analysis of a quaternary weathering profile in the virginia piedmont samples from a residual weathering profile in the virginia piedmont have been analyzed for cosmogenic 10be concentrations are highest in clay rich soil and decrease exponentially to a depth of about 15 m despite uncertainties about the processes by which 10be may be intercepted before entering the solum and eroded after incorporation a minimum age may be calculated for the regolith this calculation is based on the delivery rate of 10be and its decay rate and suggests that this residual profile developed during a period no shorter than 8 105 yr the calculated minimum age may be within a factor of 2 of maximum age estimates based on surface lowering by erosion and on the rate of rock weathering to saprolite the vertical distribution of 10be in the profile could result from a steady state balance of deposition weathering radioactive decay and erosion

beryllium isotope geochemistry in tropical river basins abstract the distributions of beryllium 9 and beryllium 10 in rivers within the orinoco and amazon basins have been examined to extend our understanding of their geochemical cycles and to develop their use both in geochronometry and in studying erosional processes beryllium 9 the stable isotope is weathered from mineral lattices before entering the riverine dissolved or exchangeable phase the cosmogenic radioisotope 10be t 1 2 1 5 myr is produced primarily in the atmosphere and is brought into riverine systems via rainfall in dissolved or exchangeable form it may be used to examine the processes which affect beryllium partitioning between the dissolved and particulate phases ancillary data such as major ion distributions provide a basis for selecting regions in which riverine chemistry is dominated by a single geochemical process allowing examination of its effects on be distributions in isolation analyses of 9be in dissolved and suspended material from rivers with a wide range of chemical compositions indicate that its geochemistry is primarily controlled by two major factors 1 1 its abundance in the rocks of the watershed and 2 2 the extent of its adsorption onto particle surfaces the relative importance of these parameters in individual rivers is determined by the extent of interaction with flood plain sediments and the riverine ph this understanding of 9be geochemistry forms a basis for examination of the geochemical cycling of 10be in rivers which are dominated by interaction with sediments the riverine concentration of dissolved 10be is far lower than that in the incoming rainwater indicating that a substantial proportion of it is retained within the soils of the basin or is adsorbed onto riverine particles however in acidic rivers in which the stable dissolved be concentration is determined by the be level in the rocks of the drainage basin dissolved 10be has essentially the same concentration as in precipitation these observations imply that the soil column in such regions must be saturated with respect to 10be and that the ratio of the inventory to the flux does not represent an age as may be the case in temperate latitudes but rather a residence time

transport of10be and9be in the ocean beryllium isotopes 10be and9be have been measured in suspended particles of 1 mm size collected by mid water sediment traps deployed in the eastern pacific at manop sites h 6 32 n 92 50 w water depth 3600 m and m 8 50 n 104 00 w 3100 m for comparison surface sediments from box cores taken from the two sites were also studied the concentrations of10be and9be in sediment trap particles are about an order of magnitude smaller than those in the bottom sediments which contain about 8 109 and 6 1016 atoms g 1 of10be and9be respectively the sediment trap samples collected from 50 m off the bottom showed significant 26 63 contributions from resuspended bottom sediments the10be 9be ratio in trap samples varies from 3 to 20 10 8 the variation may partly result from varied proportion of authigenic detrital material the fluxes of both isotopes exhibit a very strong seasonality the fluxes of10be into the traps at about 1500 m are estimated as 9 105 and 4 105 atoms cm 2 a 1 at sites h and m respectively these values are to be compared with the fluxes into the sediments of 4 5 105 atoms cm 2 a 1 at both locations good correlations exist between10be 9be and27al indicating that the primary carrier phase s for the beryllium isotopes in the water column may be aluminosilicates

spatial and temporal variations in meteoric 10be inventories and long term deposition rates colorado front range abstract atmospherically derived cosmogenic nuclides such as meteoric 10 be offer great potential in quaternary science because they can be used as landform geochronometers and as sediment tracers use of meteoric 10 be inventories for determining landform age soil residence time or erosion rates requires knowing the long term rate of deposition for this cosmogenic nuclide to the earth s surface here we present meteoric 10 be inventories measured at 6 dated sites near the boulder creek critical zone observatory front range colorado each site lies on a relatively stable landform broad moraine or fluvial terrace at slopes between 10 be deposition precipitation dryfall and dust deposition calculated from measured inventories at these sites range from 0 4 to 5 0 10 6 atoms cm 2 yr 1 none of the inventories match expected primary meteoric 10 be deposition rates that global latitude based models or precipitation specific models predict for this region meteoric 10 be inventories and calculated deposition rates at the three older 90 ka sites fall below 0 3 0 7 model predictions inventories and rates at the three pinedale age sites lgm 21 15 ka are higher 1 5 4 than model predictions previous analysis of soils in the front range over the same timeframe as these sites indicate that long term dust accumulation rates are low and associated secondary meteoric 10 be deposition is unlikely to account for the deviation from model predictions at the pinedale age sites in particular long term dustfall would have to be 1 2 orders of magnitude higher to add the meteoric 10 be required to account for measured inventories low inventories at older sites are consistent with loss of meteoric 10 be through physical erosion or selective removal of near surface soil enriched in meteoric 10 be time averaged rates of total meteoric 10 be deposition for these sites are minima we speculate that higher inventories at pinedale age sites reflect the addition of meteoric 10 be due to snowdrifts and or interflow associated with landform location increasing the effective precipitation related primary meteoric 10 be deposition at the sampled sites given these constraints and the spatial variation observed around the front range we suggest that 1 5 0 2 10 6 atoms cm 2 yr 1 is an appropriate long term meteoric 10 be deposition rate to use across much of the front range region that receives 45 55 cm of precipitation a year this long term total meteoric 10 be deposition rate is 30 50 higher than that predicted by global or annual precipitation specific models emphasizing that local calibration of deposition rates is essential for geomorphic studies around the globe

10be accumulation in a soil chronosequence we have measured the concentration of the cosmogenic isotope10be in soil samples from various horizons at six sites including three independently dated rappahannock river terraces and a previously undated piedmont soil to which we have assigned an age all of the incident10be can be accounted for in one of these soils and a second is within a factor of two in three soils whose concentrations vary widely with depth a significant fraction of the incident10be cannot be accounted for incomplete sampling and enhanced be mobility caused by organic components are the probable reasons for the low inventory of be from these three soils overall the data from these six sites indicate that10be accumulation could be used to assign ages to soils if be is not mobilized and lost from the soil profile

a shallow water model of the diurnal dryline this study explores the diurnal variation in the movement and structure of the dryline using a one dimensional shallow water model the model is adapted to test some common theories of dryline motion including the diurnal variation in surface friction static stability inversion erosion and momentum mixing aloft these mechanisms of diurnal variation are first studied individually and then in unison a diurnal variation in the surface friction produces a model dryline that moves westward during the day in disagreement with observations and has a southerly wind maximum near midnight a diurnal variation in the static stability produces a model dryline that steepens in slope and moves eastward during the day and then surges westward at night with a southerly wind maximum 6 to 9 h after the minimum stability inversion erosion during the day produces a nearly vertical model dry front that moves eastward during the day with surface southwesterlies at sunset the model dryline surges westward with a southerly wind maximum before midnight a diurnal variation of the momentum mixing aloft has no significant effect on the model dryline results show that the combined case with a diurnal variation of surface friction inversion erosion and static stability with terrain most accurately describes the observed dryline system the westward surge depicted in the model is compared to the flow evolution of the corresponding dam break problem for a rotating fluid

meteoric 10be dating of highly weathered soils from fluvial terraces in taiwan abstract stream terraces are geomorphic markers that can be used to gauge surface deformation in response to tectonic uplift the surface deposits of the terraces form a chronosequence that indicates the rate and process of soil development placing a time or age constraint upon soil development has become one of the most important factors in the disciplines of soil science and fluvial geomorphology the radiocarbon 14c method is unable to date old terraces or soils but the longer half life of cosmogenic beryllium 10 10be permits this isotope to be useful to determine soil ages and rates of formation red soils redder than 7 5yr are commonly distributed on old high altitude stream terraces throughout taiwan in this study three pedons of alluvium related red soils were sampled from the taoyang ty ym pakua pk 1 and chiayi terraces cy 1 respectively located in northern central and southern taiwan according to field morphology and chemical analyses these red soils are characterized in soil taxonomy as being highly weathered and they are classified as typic hapludox ty ym and pk 1 and typic paleudult cy 1 meteoric 10be dating shows ages of 261 ka for ty ym 124 ka for pk 1 and 386 ka for cy 1 however the trend of these ages does not agree with the degree of soil development the former two ages are likely underestimated through loss of 10be due to strong leaching and considerable erosion the age obtained from cy 1 may represent the required time for soils develop into oxisols in taiwan

chinese first deep ice core drilling project dk 1 at dome a antarctica 2011 2013 progress and performance the chinese first deep ice core drilling project dk 1 has commenced at kunlun station in the dome a region the highest plateau in antarctica during the first season within the 28th chinese national antarctic research expedition chinare 2011 12 the pilot hole was drilled and reamed in order to install a 100 m deep fiberglass casing in the next season 29th chinare 2012 13 the deep ice core drilling system was installed and all the auxiliary equipment was connected and commissioned after filling the hole with drilling fluid n butyl acetate three runs of wet ice core drilling were carried out and a depth of 131 24 m was reached drilling to the bedrock at the target depth of 3100 m is planned to be completed during a further four seasons we describe the work in progress and the status of equipment for the dome a drilling project

the depositional flux of meteoric cosmogenic 10be from modeling and observation abstract meteoric cosmogenic 10be is a powerful tracer to quantify dates and rates of earth surface processes over timescales of 103 105 yrs a prerequisite for its applications is knowledge of the flux at which 10be produced in the atmosphere is delivered to the earth surface four entirely independent approaches are available to quantify this flux 1 general circulation models gcm combined with 10be production functions and aerosol dynamics 2 10be in precipitation collections 3 10be inventories in dated soil profiles 4 riverine 10be exported in solid and dissolved forms we compiled and reprocessed published globally distributed 10be flux data from each of these methods and compared them with each other after normalization to a common atmospheric production rate based on precipitation records we propose a simple framework to discriminate between two delivery effects on 10be fluxes in the additive effect water vapor and 10be are continuously accumulating during long distance transport leading to an increase in 10be flux with precipitation rate in the dilution effect the 10be flux is delivered from proximal vapor sources limited by the rate of 10be introduction from the stratosphere and independent of precipitation rate both effects are mostly present in combination and the relative weight of either effect depends on vapor condensation rate and on the ratio of vapor condensation area to precipitation area a comparison between precipitation derived fluxes and gcm derived fluxes shows that half of the precipitation estimates are 2 times greater than gcm derived fluxes by comparison soil and gcm derived fluxes agree within a factor of 2 for more than half 57 of the dataset and the remaining soil estimates 43 are much lower than gcm derived fluxes 71 of 10be flux estimates from riverine export using 10be meteoric 9be ratios also agree with gcm derived fluxes within a factor of 2 we explain the precipitation derived fluxes that commonly exceed all other estimates by short term stochasticity in precipitation events that might introduce a measurement time interval bias towards higher fluxes this bias is not present over longer term 103 105 yrs flux estimates like those from soil profiles soil derived fluxes might still present an underestimation when retention of 10be in soil is incomplete we recommend producing more 10be depositional flux data from soil inventories with full be retention as these generate in our view the most relevant estimates for applications of meteoric 10be on millennial scale earth surface processes

10be chronometry of bedrock to soil conversion rates abstract we report concentrations of cosmogenic 10 be t 1 2 1 5 10 6 yrs in soil excavated from a soil mantled hillslope in black diamond mines regional park contra costa county california the most striking features of the data are 1 the similarity in the downward decreasing trends of 10 be concentrations in two soil profiles collected 75 m apart 2 the coincidence in each soil profile of the soil bedrock interface as defined by visual inspection of soil pits and the level at which 10 be concentrations attain very low values 4 10 6 atoms g and 3 the extremely low 10 be concentrations in the underlying regolith 0 5 10 6 atoms gram the inventory of 10 be in these soils is low equivalent to about 6000 yrs of 10 be accumulation in a soil initially containing no 10 be on the basis of these measurements and with the aid of simple models of soil 10 be motions on the hillslope we conclude that 10 be loss from the surface is dominated by its removal in soil by creep we calculate local rates of bedrock to soil conversion of between 0 15 and 0 27 km 10 6 yrs comparing these with uplift rates determined for coastal regions of california indicates that soil creep alone is capable of removing soil from the local geomorphic system at a rate equivalent to the rate of uplift of much of the coast

combining bulk sediment osl and meteoric 10be fingerprinting techniques to identify gully initiation sites and erosion depths deep erosional gullies dissect landscapes around the world existing erosion models focus on predicting where gullies might begin to erode but identifying where existing gullies were initiated and under what conditions is difficult especially when historical records are unavailable here we outline a new approach for fingerprinting alluvium and tracing it back to its source by combining bulk sediment optically stimulated luminescence bulk osl and meteoric 10be 10bem measurements made on gully derived alluvium samples in doing so we identify where gully erosion was initiated and infer the conditions under which such erosion occurred as both 10bem and bulk osl data have distinctive depth profiles in different uneroded and depositional settings we are able to identify the likely incision depths in potential alluvium source areas we demonstrate our technique at birchams creek in the southeastern australian tablelands a well studied and recent example of gully incision that exemplifies a regional landscape transition from unchanneled swampy meadow wetlands to gully incision and subsequent wetland burial by post european settlement alluvium we find that such historic alluvium was derived from a shallow erosion of valley fill upstream of former swampy meadows and was deposited down the center of the valley incision likely followed catchment deforestation and the introduction of livestock which overgrazed and congregated in valley bottoms in the early 20th century during a period of drought as a result severe gully erosion was likely initiated in localized compacted and oversteepened reaches of the valley bottom

low level jet development during a numerically simulated return flow event the evolution of the southerly low level jet llj during a return flow event is studied using output from the penn state ncar mesoscale model version 4 three geographically different southerly lljs develop in the simulation one over the southern plains of the united states a second southwest of brownsville texas and a third over the western gulf of mexico the llj over the plains is found to form first as an inertial oscillation and later as a response to lee troughing and an elevated mixed layer that develops over the region over mexico the temperature structure over the altiplanicie mexicana mexican high plain is responsible for a locally intense low level pressure gradient east of the high plain which remains nearly stationary over two diurnal cycles the llj over the western gulf of mexico results largely from topographic blocking of the low level southerly flow by the eastern end of the neovolcanic cordillera northwest of veracruz mexico the evolution of the lower troposphere over the southern plains resembles the carlson and ludlam conceptual model for a severe storm environment but the structure of the return flow is complex when midlevel westerlies are weak mesoscale and boundary layer processes govern the development of lljs as the west and southwesterly winds increase with an approaching upper level disturbance synoptic influences overwhelm the mesoscale processes leading to a single larger scale llj

10be in chinese loess we report a first series of10be measurements on chinese loess covering the last 750 000 years the10be concentration shows a tendency to decrease with increasing grain size leaching experiments with acid solutions show that10be is strongly bound to particles and therefore mobility due to dissolution can be excluded the10be record in loess shows features similar to those observed in 180 records from deep sea sediments which strongly reflect climatic variations this allows one to correlate the10be loess records with 180 deep sea records and to establish a time scale based on this time scale accumulation rates of loess and10be fluxes can be calculated these reveal generally higher values for cold arid and windy periods than for warm humid and calmer intervals

beryllium 10 in deep sea sediments a tracer for the earth s magnetic field intensity during the last 200 000 years abstract we present a new approach for the reconstruction of the earth s magnetic field intensity during the last 200 000 years based on 10 be in deep sea sediments a simple box model that is able to describe boundary scavenging of 10 be in the ocean is used to study the sensitivity of 10 be to changes of water circulation and or varying particle rain rates the model is applied to separate transport and production signal in single 10 be records vertical sediment accumulation rates are used as input values for the model calculations the calculated scavenging factors are applied to correct the 10 be records for boundary scavenging the model corrected 10 be based paleointensity record correlates well with other records from very different archives

the laschamp geomagnetic dipole low expressed as a cosmogenic 10 be atmospheric overproduction at 41 ka authigenic 10be 9be ratiomeasurementswere performed at high resolution along a portuguese margin deep sea core 37 48 n 10 09w spanning the 20 50 ka time interval in order to reconstruct variations in atmospheric cosmogenic 10be production rates and derive the related geomagnetic dipole moment modulation a complementary approach consisting in 230thxs normalized 10be deposition rate determination on selected samples confirmed the reliability of the authigenic 10be 9be record this study constitutes the first successful comparison of the two widely used normalization techniques of 10be concentrations for both methods the presented results herein evidence a factor of 2 cosmogenic nuclide overproduction linked to a minimum dipole moment associated with the laschamp excursion the latter is stratigraphically constrained beneath heinrich event 4 its age is estimated at 41 ka on the basis of direct correlation between the series of rapid paleoclimatic events recorded in the portuguese margin sediments and in the greenland ice sheet and is confirmed by calibrated radiocarbon dating carried out on the same sediments the remarkable agreement between the authigenic 10be 9be and the greenland ice cores 10be deposition rate records attests to their global significance this new authigenic 10be 9be record has been combined with that previously obtained at the same site to produce a stacked record that is calibrated using absolute values of virtual dipole moment determined on lava flows this provides a reconstruction of dipole geomagnetic moment variations over the 20 50 ka interval independent frompaleomagnetically constrainedmethods that documents the laschamp dipole low but fails to express any dipole low related to t e mono lake excursion this high resolution record responds to the necessity of supplementing the knowledge of the atmospheric 14c variations in the 30 45 ka interval during which the 14c calibration curve suffers from a lack of accurate data and during which a discrepancy of about 5500 yr between the 14c and u th ages is due to the laschamp geomagnetic dipole low such new high resolution datasets from records obtained from different latitudes will be required to make significant advances in understanding the causes of atmospheric 14c variations

southerly low level jet in the winter cyclones of the southwestern great plains abstract on the basis of 20 cases in the winter half year it is found that a southerly low level jet llj is regularly associated with extratropical cyclones in the southwestern great plains only very weak and short lived lows are not associated with an llj a composite model is constructed that shows the typical sequence of events during the formation of the llj in the texas colorado area this jet is initially dry since it develops over the continent only in the advanced stage 1 2 days after its inception and as it expands over a wide area does the llj start drawing water vapor from the gulf of mexico

beryllium isotope systematics of submarine hydrothermal systems abstract both 10 be and 9 be concentrations have been measured in a hydrothermal fluid from the sediment starved east pacific rise at 21 n as well as in fluids and associated sediments from the sediment covered guaymas basin and escanaba trough hydrothermal systems the results show that while the 9 be concentrations in fluids from both types of systems are comparable about three orders of magnitude higher than that of the seawater supplying the systems their 10 be concentrations are significantly different the 10 be concentration in the solution emanating from the studied sediment starved hydrothermal system is at least two times lower than that of the pacific bottom water by contrast the 10 be concentration in hydrothermal solutions from sediment hosted environments are enriched over ambient seawater and are at least one order of magnitude higher than that measured in the 21 n fluid the sedimentary cover being the only available source of 10 be in these systems these data demonstrate that 10 be is an unambiguous tracer of interactions between hydrothermal fluids and recent sediments as an example this study examines hydrothermal solutions from the sediment starved mariana trough back arc basin which have compositions similar in many respects to those from sediment hosted environments however these fluids are depleted in 10 be relative to ambient seawater which precludes interaction with recent sediment as the cause of their peculiar chemical composition

increased production of cosmogenic 10 be recorded in oceanic sediment sequences information on the age duration and amplitude of the geomagnetic dipole moment minimum over the matuyama brunhes transition new high resolution authigenic be 10 be 9 ratio be ratio records covering the last geomagnetic reversal i e the matuyama brushes transition mbt have been obtained and set on a time scale using benthic delta o 18 cibicides wuellerstorfi records the geographic distribution of the four studied sites allows global comparison between the north atlantic indian and pacific oceans all be ratio records contain a twofold increase triggered by the geomagnetic dipole moment gdm collapse associated with the mbt the stratigraphic position of the be ratio spike relative to marine isotope stages allows establishment of a robust astrochronological framework for the mbt anchoring its age between 778 and 766 ka average mid peaks at 772 ka which is consistent with all other available be 10 proxy records from marine ice and loess archives the global be 10 atmospheric production doubling represents an increase of more than 300 atoms m 2 s 1 that is compatible with the increased magnitude of atmospheric be 10 production obtained by simulations between the present gdm and a null gdm the minimum be 10 derived gdm average computed for the 776 771 ka interval is 1 7 0 4 x 10 22 am 2 in agreement with model simulations and absolute paleointensities of transitional lava flows

10be study of rapid erosion in taiwan cosmogenic 10be was measured using accelerator mass spectrometry in soils and sediments to study the erosion of taiwan which has the highest denudation rate in the world the river sediments in taiwan have very low 10be concentrations around 5 million atoms per gram about 145 the world wide average this is the direct consequence of its high sediment yield of more than 1000 mg cm2 yr 70 times the world average combining these values we found that for taiwan as a whole the 10be output to the sea only slightly exceeds the input from the rain a situation typical of many areas around the world therefore even in this example of extremely rapid erosion 10be seems to remain a useful indicator for erosion status the total 10be inventory found in a soil profile from a geologically stable area is at least 18 of the maximum possible inventory the minimum age thus estimated for the soil is 0 11 ma in reasonable agreement with estimates from other means the maximum erosion rate for this area thus estimated is at most 0 14 mg cm2 yr four orders of magnitude slower than the average value observed for taiwan we also demonstrate that the shelf sediments around taiwan have received the admixing of a 10be rich component from the ocean and would give a poor estimate for material eroded from taiwan

geochemical and geophysical implications of the radiocarbon calibration abstract a precise and accurate chronological framework is crucial to study the dynamics of a variety of phenomena which occurred during the last 45 000 years although the 14 c dating method has been widely applied since the 1950s it is recognized that the atmospheric 14 c 12 c ratio has not been stable during the past in order to calculate accurate ages these fluctuations have to be corrected by means of a calibration curve obtained by comparing raw 14 c measurements with true calendar ages provided by independent dating methods the calibration curve obtained so far is characterized by a long term trend with raw 14 c ages being significantly younger than calendar ages during most of the last 45 000 years abrupt 14 c shifts which occurred over centuries to millennia are superimposed on this long term trend of decreasing atmospheric 14 c 12 c ratio to a certain extent it is possible to outline the different causes of atmospheric 14 c variations by considering complementary information obtained from other cosmogenic nuclides studied at different latitudes 1 most high frequency changes in the atmospheric 14 c 12 c ratio are linked to magnetic fluctuations of solar origin as revealed by studying the last three centuries for which direct observations of the sun are available a similar conclusion is derived by comparing 14 c 12 c events with 10 be and 36 cl concentration maxima in polar ice cores 2 the long term trend shift of 14 c ages is due to a long period of decreased shielding effect of the geomagnetic dipole field which occurred over the interval between 10 000 and 40 000 years bp this interpretation is supported by paleomagnetic measurements performed on volcanic and sedimentary rocks and by 10 be and 36 cl analysed in low and high latitude records 3 a prominent and rapid atmospheric 14 c 12 c excursion occurred between 13 000 and 11 500 cal yr bp thus corresponding to the younger dryas cold period by contrast with the 14 c variability mentioned above which is linked to 14 c production changes this so called 14 c age plateau is probably due to an abrupt variation in the rates of exchange within the global carbon cycle this interpretation is supported by independent geochemical proxies and by numerical modelling of the carbon cycle

10be concentrations and the long term fate of particle reactive nuclides in five soil profiles from california concentration depth profiles of cosmic ray produced 10 be t 1 2 1 5m y have been measured by accelerator mass spectrometry in five soil profiles these measurements were made in an effort 1 to understand the retentivity of soil surfaces for particle reactive tracers depositing from the atmosphere on time scales of 10 4 10 6 years and 2 to explore the application of 10 be as a chronometer of geomorphic surface age the profiles sampled are from two wave cut terraces located near mendocino california a table mountain top and an alluvial fan both located near friant california the ages of the mendocino terraces are inferred to be 1 5 10 5 years based on amino stratigraphic correlations and models of terrace evolution those of the table mountain top and alluvial fan are 9 5 10 6 years and 6 0 10 5 years respectively based on k ar analyses all the surfaces sampled are nearly flat and exhibit few erosional features in addition to 10 be we measured 210 pb 239 240 pu and 7 be to ascertain the retentivity of the soils for particle reactive nuclides and to assess the present day delivery rate of nuclides from the atmosphere the 7 be inventory is 4 0 dpm cm 2 similar to those observed at nearby locations the inventories of 210 pb and pu isotopes conform to those predicted from model calculations and suggest that the soil surfaces sampled retain the entire burden of particle reactive nuclides delivered to them over short time scales 100 years the 10 be concentrations in the sample range between 0 2 and 7 10 8 atoms g soil and show strong correlations with leachable fe and or al the inventory of 10 be in the soil domain sampled is 1 2 orders of magnitude lower than that expected from the geological age of the surface and an average delivery rate of 10 be from the atmosphere 5 2 10 5 atoms cm 2 yr the low inventory of 10 be is attributed to its loss from the soil domain sampled by solution transport based on a simple model type calculation with a first order removal process for 10 be the residence time of 10 be in the soil domains sampled is determined to be of the order of 10 4 years the low residence time of 10 be in the soil domains sampled requires that it be found either deeper in the regolith or in ground waters in either case the application of 10 be as a chronometer of geomorphic surface age is severely constrained however the study of 10 be in soils provides the only entry into the long term 10 4 10 6 years behavior of particle reactive nuclides in soils and hence could be important for understanding the behavior of analogous nuclides introduced into soils by natural and anthropogenic processes

26al 10be and u th isotopes in blake outer ridge sediments implications for past changes in boundary scavenging we have investigated the distributions of 26 al 10 be u th isotopes and stable 27 al and 9 be in core ch88 11p 30 40pn 74 41pw 3337 m from the blake outer ridge bor in the western north atlantic an area that is characterized by high terrigenous input results show authigenic 26 al 27 al of 6 2 8u10 314 atom atom authigenic 10 be 9 be of 0 5 2 6u10 38 atom atom 6 0 2 1 8u10 6 atoms g of 26 al and 5 3 15 1u10 8 atoms g of 10 be in the core over the last glacial interglacial cycle these values as well as total 230 thex 232 th and 10 be 9 be ratios were all at their minima during the last glacial maximum lgm reflecting intensified terrestrial influx to the area aluminosilicate material clays in this influx preferentially scavenged 230 th over the two other particle reactive nuclides 26 al and 10 be such that their boundary scavenging during lgm followed the order 230 ths 10 bes 26 al as opposed to 10 bev 230 ths 26 al in the holocene they appear at variance with the order 10 bes 26 alw 230 th as would be predicted from the relative particle reactivities of the three species these scavenging characteristics point to 10 be 26 al as a potentially more suitable proxy for paleoproductivity than 10 be 230 thex mass balance considerations for 26 al and 10 be show a five fold lgm to holocene increase in deep water circulation in the study area with little change in ocean productivity except during the deglaciation when it increased noticeably fl 2001 elsevier science b v all rights reserved

a mediterranean perspective on 10be sedimentation and climate around the matuyama brunhes boundary les liaisons dangereuses abstract the 10be 9be ratio is commonly employed as a tool for establishing the stratigraphic position of paleomagnetic excursions and reversals whenever the traditional paleomagnetic approach fails to provide conclusive results in particular it is held that 10be production rates in the atmosphere depend on the strength of the earth s magnetic field and the fallout and deposition of cosmogenic beryllium at the surface happen on a very short time scale however investigations performed on terrestrial and marine successions demonstrate that the 10be record and the paleomagnetic signal are often asynchronous mechanisms that control the conveyance and deposition of cosmogenic 10be to the seafloor are still ambiguous and poorly documented here we discuss the dynamics of 10be in a central mediterranean marginal marine depositional scenario characterized by a pervasive terrigenous influx our data show that a very close correlation exists between 10be concentrations and the local proxy of rainfall rates and regimes pollen indicating that a considerable 10be transport from the mainland may occur in response to the remobilization of terrestrial reservoirs during periods of increased runoff superimposed is a dynamic oceanographic setting that further controls the preservation potential of 10be at the bottom in terms of changing water chemistry and or composition of the sedimentary flux to the seafloor results of our investigation suggest that in particular environmental and depositional settings the interplay between climate terrigenous yield and oceanography may jeopardize the sedimentary depiction of the meteoric 10be contribution thus challenging the use of 10be for tracking the stratigraphic position of geomagnetic reversals

soil formation and weathering in a permafrost environment of the swiss alps a multi parameter and non steady state approach spatially discontinuous permafrost conditions frequently occur in the european alps how soils under such conditions have evolved and how they may react to climate warming is largely unknown this study focuses on the comparison of nearby soils that are characterised by the presence or absence of permafrost active layer thickness 2 3 m in the alpine tundra and subalpine forest range of the eastern swiss alps using a multi method geochemical and mineralogical approach moreover a new non steady state concept was applied to determine rates of chemical weathering soil erosion soil formation soil denudation and soil production long term chemical weathering rates soil formation and erosion rates were assessed by using immobile elements fine earth stocks and meteoric 10be in addition the weathering index k ca ti the amount of fe and al oxyhydroxides and clay minerals characteristics were considered all methods indicated that the differences between permafrost affected and non permafrost affected soils were small furthermore the soils did not uniformly differ in their weathering behaviour a tendency towards less intense weathering in soils that were affected by permafrost was noted at most sites weathering rates the proportion of oxyhydroxides and the weathering stage of clay minerals were lower in permafrost soils in part erosion rates were higher at the permafrost sites and accounted for 79 97 of the denudation rates in general soil formation rates 8 8 86 7 t km2 y were in the expected range for alpine soils independent of permafrost conditions it seems that the local microenvironment particularly vegetation and subsequently soil organic matter has strongly influenced denudation rates as the climate has varied since the beginning of soil evolution the conditions for soil formation and weathering were not stable over time soil evolution in high alpine settings is complex owing to among others spatio temporal variations of permafrost conditions and thus climate this makes predictions of future behaviour very difficult this article is protected by copyright all rights reserved

earth surface erosion and weathering from the 10be meteoric 9be ratio abstract the isotope ratio of the meteoric cosmogenic nuclide 10 be to the mineral derived stable isotope 9 be discloses both the earth surface denudation rate and its weathering intensity we develop a set of steady state mass balance equations that describes this system from a soil column over the hillslope scale to an entire river basin the prerequisites making this new approach possible are 1 the 9 be concentration of parent rock typically 2 5 0 5 ppm in granitic and clastic sedimentary lithologies is known 2 both be isotopes equilibrate between the fluids decomposing rock and reactive solids formed during weathering and 3 a critical spatial scale is exceeded at which the fluxes of both isotopes into and out of the weathering zone are at steady state over the time scale of weathering typically 10 kyr for these cases the isotope ratios can be determined in bulk sediment or soil on leachates from the reactive adsorbed and pedogenic mineral bound phase in sediment or soil and even on the dissolved phase in river water the 10 be 9 be ratio offers substantial advantages over the single isotope system of meteoric 10 be the latter system allows to directly determine erosion rates only in the case that 10 be is fully retentive in the weathering zone and that riverine sorting has not introduced grain size dependent 10 be concentration gradients in sediments we show the feasibility of the 10 be 9 be tracer approach at the river scale for sediment and water samples in the amazon basin where independent estimates of denudation rates from in situ produced 10 be exist we furthermore calculate meaningful denudation rates from a set of published 10 be 9 be ratios measured in the dissolved load of globally distributed rivers we conclude that this isotope ratio can be used to reconstruct global paleo denudation from sedimentary records