geoarchaeological evidence for the construction irrigation cultivation and resilience of 15th 18th century ad terraced landscape at engaruka tanzania agricultural landscapes are human manipulated landscapes most obviously in areas modified by terracing and or irrigation examples from temperate arid and desert environments worldwide have attracted the attention of many disciplines from archaeologists palaeoecologists and geomorphologists researching landscape histories to economists agronomists ecologists and development planners studying sustainable resource management this article combines these interdisciplinary interests by exploring the role archaeology can play in assessing sustainability our case study is engaruka tanzania archaeologically famous as the largest abandoned irrigated and terraced landscape in east africa the site has been cited as an example of economic and or ecological collapse and it has long been assumed to have been irrigated out of necessity because agriculture was presumed to be nearly impossible without irrigation in what is now a semiarid environment geoarchaeological research refutes this assumption however demonstrating that parts of the site flooded with sufficient regularity to allow the construction of more than 1000 ha of alluvial sediment traps in places greater than 2 m deep soil micromorphology and geochemistry also record changes in irrigation with some fields inundated to create paddylike soils geoarchaeological techniques can be applied to both extant and abandoned agricultural systems thereby contributing to an understanding of their history function and sustainability

surface circulation in the gulf of cadiz 2 inflow outflow coupling and the gulf of cadiz slope current 1 a study of the upper slope circulation in the gulf of cadiz is presented observations both original and revisited and realistic numerical modeling are used together to describe the structure and variability of the slope current system above the mediterranean outflow it is shown that the mediterranean inflow outflow coupling plays a stronger role than that of the atmospheric forcing in driving the upper slope currents the mediteranean outflow forces a surface open ocean current toward the strait of gibraltar part of it is entrained into the outflow and the remaining flows into the mediterranean this latter component does not suffice for the observed transport of the atlantic inflow into the mediterranean a secondary contribution to the inflow is therefore needed to complement the transport this contribution comes from a persistent equatorward current along the upper slope between cape st vincent and the strait of gibraltar the jet is 20 30 km wide and significant in the upper 200 m attaining subinertial maxima as much as 0 3 0 4 m s and monthly means in the order of 0 1 0 15 m s this current shows a strong variability at time scales in the order of 2 8 days and displays a significant vertical shear the response of the upper slope current to synoptic and seasonal atmospheric variability is analyzed very low correlation was detected at synoptic scales and the response of the system to seasonal forcing is unclear a cycle of intensification in june july and a decrease in winter is apparent in the measurements but is weak in the model results it is speculated that the cycle in the observed currents is associated with variability in the inflow outflow coupling system rather than driven by seasonally changing wind forcing

on the origin of the warm inflow to the nordic seas abstract warm and saline waters enter the nordic seas from the south as part of the warm to cold water transformation of the thermohaline circulation of the northern north atlantic one explanation for the origin of the nordic seas inflow is a shallow source hypothesis under which the inflow waters are a modification of upper ocean subtropical waters warm waters from the subtropical gyre are carried to the eastern north atlantic by the north atlantic current and branch northwards joined by poleward upper thermocline flow along the upper continental slope to provide the nordic seas inflow along this pathway the upper water column is progressively cooled and freshened by winter convection the subpolar mode water transformation process and this sets the inflow characteristics a deep source hypothesis provides an alternative explanation for the characteristics of the nordic seas inflow and the pathway delivering the waters to the inflow under this hypothesis inflow waters originate from the core of the mediterranean overflow waters in the gulf of cadiz carried northward at mid depth by the eastern boundary undercurrent in the subtropics continuing into the subpolar gyre along the eastern boundary and rising from depths near 1200m in the rockall trough to less than 600m to cross the wyville thomson ridge into the faroe shetland channel and thence to the nordic seas the deep source hypothesis focus is on lower thermocline source waters beneath the sill depth for the nordic seas inflow in contrast to the shallow source hypothesis focus of transformation of upper thermocline waters above the sill depth on the basis of regional water mass distributions geostrophic shear and direct current measurements we reject the deep source hypothesis in favor of the shallow source hypothesis rather than a flow of deep mediterranean overflow water along the eastern boundary rising from depth to feed the nordic seas the inflow is supplied directly by transformed north atlantic current waters from the same depth range as the inflow mediterranean overflow water is a constituent of the inflow but only through its contribution to defining the temperature salinity relationship of the interior of the subtropical gyre from which the north atlantic current draws its water rather than by direct northward advection of mediterranean outflow water via the eastern boundary undercurrent crossing from the subtropics into the subpolar domain instead the eastern boundary undercurrent wholly expels its transport of mediterranean overflow water into the eastern edge of the subtropical gyre creating the mid depth westward extending subtropical salinity plume for the lower thermocline isopycnal range of the core of the mediterranean overflow water measurements show that at the wyville thomson ridge the flow is southward and descending rather than northward and rising representing cold spillover from the faroese channels entraining warm upper ocean waters as the spillover plume descends and warms into the northern rockall trough no evidence is found in rockall trough northward of 54 n porcupine bank for direct advection of mediterranean overflow waters via an eastern boundary undercurrent extension and the very dilute mediterranean overflow waters in the trough reflect the interaction of the wyville thomson ridge plume descending into the trough from the north and lower thermocline waters delivered to the trough from the south

on the variability of the mediterranean outflow water in the north atlantic from 1948 to 2006 1 recent work has shown that variability in the properties and or transport of mediterranean seawaters spilling across the strait of gibraltar into the north atlantic have had little impact on the variability of mediterranean outflow water mow in the that basin over the past fifty years here we investigate whether circulation changes are the dominant source of mow variability in the north atlantic between 1948 and 2006 using a 1 3 north atlantic configuration of the hybrid coordinate ocean model combined with the marginal sea boundary condition model two simulations forced by either climatological or interannual atmospheric fields are performed the interannual simulation reproduces the observed mow variability without mediterranean seawater changes thus we conclude that mow variability in the last 60 years is a consequence of circulation changes in the north atlantic a series of simulations that separate the mechanical effect of the wind from the impact of buoyancy forcing show that mow variability can be attributed to shifts between its dominant northward and westward pathways the pathway shifts from predominantly northward between 1950 and 1975 to predominantly westward between 1975 and 1995 and finally back to northward after 1995 though these pathway shifts appear to be wind induced the property changes are caused by the combined impact of wind and buoyancy forcing on the circulation of the north atlantic

pliocene and quaternary depositional model of the algarve margin contourite drifts gulf of cadiz sw iberia seismic architecture tectonic control and paleoceanographic insights abstract the contourite drifts off southwest iberia that formed as a result of the interaction of the mediterranean outflow water mow with the continental middle slope were studied in the algarve margin using multichannel reflection seismic lines oil wells piston cores and a bathymetric compilation of four datasets the seismostratigraphic interpretation of a dense array of oil industry seismic and stratigraphic correlation allowed the identification of five seismic units of early pliocene through holocene in the faro and albufeira drifts and four correlative seismic units in the lagos and sagres drifts and three in the portimao drift a three phased evolutionary model for the contourite formation is proposed firstly a precursory phase of pliocene age made up of sheeted drifts represents an initial phase of deposition under bottom current activity that is correlated with the first stages of an enhanced mow at about 3 5 ma secondly the building up phase of early pleistocene age is related to a strengthening of the mow close to the onset of the northern hemisphere glaciations at about 2 6 ma during which were deposited low mounded drifts thirdly the growing phase from middle pleistocene through holocene suggests the presence of a stronger mow since the beginning of the middle pleistocene transition at about 1 3 1 0 ma accounting for the deposition of mounded drifts and formation of the alvares cabral moat seismostratigraphic interpretation and isochron maps allowed for the establishment of the main oceanographic climatic morphologic and tectonic factors that controlled the drifts deposition i the pliocene and quaternary mow circulation forced by climate changes ii the sea bottom topography inherited from the late miocene mainly shaped by the portimao lagos and bartolomeu dias canyons system iii the interaction between along slope and down slope processes since the pliocene and iv pliocene quaternary fault activity and diapirism

influence of inheritance and pedogenesis on heavy metal distribution in soils of sicily italy abstract the recognition of the potential health hazards associated with heavy metals has focused attention on the levels and behaviours of these elements both in natural and contaminated environments various soil types developed from different parent materials in sicily italy have been analysed in order to compare heavy metal distribution under different geopedological conditions total metal concentrations metal partitioning and distribution profiles are discussed in relation to the inheritance factor and pedogenic processes parent material composition largely influences the contents of heavy metals in most of the analysed soils mainly differentiating pedons for their metal concentration on the basis of sedimentary and volcanic parent materials however an exception is represented by the carbonate free alfisols and mollisols which are markedly enriched in heavy metals with respect to the underlying limestones and calcarenites on the basis of chemical and mineralogical results supported by data from sequential extraction sep heavy metal enrichment in these soils is associated with the formation of common to abundant fe mn oxides and clay accumulation for mollisols there is evidence for a major role of organic matter in heavy metal retention in surface horizons in the other pedons pedogenic processes appear to mainly influence the redistribution of heavy metals throughout the soil horizons rather than affecting the total content argillopedoturbation seems to be responsible for a uniform distribution of heavy metals in vertisol profiles on marly clays accumulation of heavy metals in the topsoil of inceptisols on clays with gypsum and entisols on gypsarenites and diatomites is caused partially by adsorption on organic matter and mainly by dissolution of primary gypsum and opal a a pedogenic influence is less evident in young andisols whose heavy metal composition greatly reflects that of hawaiitic pyroclastic deposits interbedded within the profiles however a certain redistribution of cu accumulated as metal organic matter complexes is evidenced in the surface horizon by sep

a regional modeling study of the entraining mediterranean outflow 1 we have evaluated a regional scale simulation of the mediterranean outflow by comparison with field data obtained in the 1988 gulf of cadiz expedition our ocean model is based upon the hybrid coordinate ocean model hycom and includes the richardson number dependent entrainment parameterization of xu et al 2006 given realistic topography and sufficient resolution the model reproduces naturally the major observed features of the mediterranean outflow in the gulf of cadiz the downstream evolution of temperature salinity and velocity profiles the mean path and the spreading of the outflow plume and most importantly the localized strong entrainment that has been observed to occur just west of the strait of gibraltar as in all numerical solutions there is some sensitivity to horizontal and vertical resolution when the resolution is made coarser the simulated currents are less vigorous and there is consequently less entrainment our richardson number dependent entrainment parameterization is therefore not recommended for direct application in coarse resolution climate models we have used the high resolution regional model to investigate the response of the mediterranean outflow to a change in the freshwater balance over the mediterranean basin the results are found in close agreement with the marginal sea boundary condition msbc a more saline and dense mediterranean deep water generates a significantly greater volume transport of the mediterranean product water having only very slightly greater salinity

tracking textural mineralogical and geochemical signatures in soils developed from basalt derived materials covered with loess sediments sw poland abstract this study investigates the scale of inheritance of signatures typical of loess and basalt derived substrates in soils having both components present as parent material due to past periglacial processes based on field description particle size distribution mineralogy heavy minerals and clay minerals as well as geochemistry we track the signal of both materials local basalt derived and loess derived estimate the maximum thickness of loess mantles and mixed zones having both loess and basaltic components and note the presence or absence of basal layers without allochtonous additions the results show that geochemistry and heavy minerals are the most reliable proxies for a verification of aeolian silt contributions and to define individual layers in complex soil parent materials soil formation in the studied landscape depends on the type of slope sediments typical fine grained weathering of basalt without input from aeolian silt would promote rather vertic development however in thick loess deposits as well as in thin silt textured materials superimposed on clay loam beds clay illuviation dominates development of argic horizons however results in decreasing permeability promoting water stagnation and enhanced degradation processes in clay rich subsoil instead of luvisols stagnosols and retisols developed in the study regions basaltic block covers mixed with loess host cambic horizons based on our findings it seems that at the edge of thin loess deposits no soils exist that developed exclusively from basaltic parent materials

a comparison between the generalized digital environmental model and levitus climatologies two ocean climatologies of temperature and salinity the generalized digital environmental model gdem and the climatological atlas of the world ocean are compared dynamic height fields are computed by season from each climatology for the north atlantic north pacific and indian oceans and are compared on a 1 latitude longitude grid large scale oceanographic features are generally found to be similarly represented in both climatologies gdem appears to render better representations of seasonal variability and regions of high current shear such as the gulf stream because of a different smoothing method and a finer grid spacing maps of dynamic heights from both climatologies are presented and their similarities and differences are discussed the methodology for the construction of gdem is also described in detail

paleorainfall reconstructions from pedogenic magnetic susceptibility variations in the chinese loess and paleosols the rock magnetic properties of the chinese loess and paleosols constitute a unique and sensitive record of east asian paleoclimate through the quaternary period systematic variations in the concentration and grain size of the magnetic minerals in these sediments have produced systematic variations in the magnetic susceptibility signal which can be easily and rapidly measured at many sites across the loess plateau variations in many other rock magnetic properties can be used to identify the key shifts in ferrimagnetic grain size but magnetic susceptibility alone is sufficiently sensitive to record stadial and interstadial climate stages as well as glaciations and interglaciations past changes in rainfall and monsoon activity for this region are reconstructed from the susceptibility variations the susceptibility record is calibrated using the modern relationship between rainfall and pedogenic susceptibility on the loess plateau our rainfall reconstructions identify enhanced summer monsoonal activity in the chinese loess plateau region in the early holocene and the last interglaciation in the presently semiarid western area of the plateau annual precipitation in interglacial times was up to 80 higher than at present in the more humid southern and eastern areas values were up to 20 higher than today s levels during the last glaciation precipitation decreased across the entire plateau typically by 25 the relationship between pedogenic susceptibility climate and weathering age was examined over the northern hemisphere temperate zone and the observed positive correlation between rainfall and susceptibility indicates that climate rather than soil age is the predominant factor that controls pedogenic susceptibility enhancement in loess soils

stress on the mediterranean outflow plume part i velocity and water property measurements abstract in september 1988 six sections were occupied across the mediterranean outflow plume in the gulf of cadiz within 100 km of the strait of gibraltar vertical profiles of temperature and salinity were collected at ctd stations velocity and temperature profiles were collected with expendable current profilers at a subset of these stations at the channel base the plume undergoes geostrophic adjustment and turns northwest to flow along the continental slope there it decelerates and spreads gradually down the slope as friction slows the current and allows it to cross isobaths within the plume downstream velocity and density increase rapidly in the interfacial layer with depth to the velocity maximum or nose 5 150 m above the bottom below the nose in the bottom layer downstream velocity decreases rapidly toward the bottom but the stratification is weak ekman like veering occurs in the interfacial layer local bottom stresses on the plume are estimated by fitting the near bottom velocity prof

an andosol cambisol toposequence on granite in the austrian bohemian massif in europe non allophanic andosols are linked with hercynian basic and metabasic rocks in smoothed highlands with a cool and humid climate we describe an andosol cambisol toposequence derived from variscan coarse grained granite in northern austria bohemian massif where andosols have formed on plateaus and cambisols on steep slopes the climate is continental cool and humid mean annual temperature and rainfall 5 4 degreesc and 914 mm with a 100 day mean annual period of snow cover the forest is dominated by beech and spruce trees both soils are rich in organic matter and strongly acidic but the andosol is more strongly weathered than the cambisol below the 15 cm thick litter in the andosol the 38 cm thick ab bw solum is dark reddish brown to strong brown has a large c content 9 0 4 4 and meets all the requirements of an andic horizon in these horizons oxalate extractable iron content 1 62 8 fe o represents 76 84 of free iron and is much larger than al o 0 8 1 5 both biotite and plagioclase are sources of fe and al the fort nation of non allophanic andosol from granite was likely due to the combination of the following factors cool and humid climate large accumulation of organic matter high infiltration rate intense water percolation during spring thawing and significant content of weatherable minerals as such conditions are not rare in european highlands andic soils are probably more widespread in europe than is currently thought c 2003 elsevier b v all rights reserved

geochemical behaviour of ni cr cu zn and pb in an andosol cambisol climosequence on basaltic rocks in the french massif central abstract the objective of this study is to identify parameters influencing trace elements te vertical distributions in an andosol andic cambisol climosequence in order to understand processes involved in the current distribution of trace elements from basaltic rocks to associated soils six pedons developed on tertiary massive basaltic formations located at similar position in the hill slopes submitted to the same wet mountainous climate but under various microclimatic conditions altitude and annual rainfall were considered the six studied soils are andic and rich in organo metallic complexes two different and quantitative methods were used to compare the geochemical distributions of major and trace elements both being calculated with ti as invariant element isovolumetric mass balance and enrichment factors anthropogenic pedogenetic microclimatic inherited factors were discriminated anthropogenic influences are pointed out for k in two pedons and for pb in all studied sites distributions of other te are affected by discontinuities between underlying rocks and soil horizons zinc and cu distributions are controlled by organic matter whereas cr and ni distributions are influenced by pedogenetic processes results emphasize the relative trace element immobilization in andic soils under temperate climate

directly measured mid depth circulation in the northeastern north atlantic ocean the circulation of water masses in the northeastern north atlantic ocean has a strong influence on global climate owing to the northward transport of warm subtropical water to high latitudes but the ocean circulation at depths below the reach of satellite observations is difficult to measure and only recently have comprehensive direct observations of whole ocean basins been possible here we present quantitative maps of the absolute velocities at two levels in the northeastern north atlantic as obtained from acoustically tracked floats we find that most of the mean flow transported northward by the gulf stream system at the thermocline level about 600 m depth remains within the subpolar region and only relatively little enters the rockall trough or the nordic seas contrary to previous work our data indicate that warm saline water from the mediterranean sea reaches the high latitudes through a combination of narrow slope currents and mixing processes at both depths under investigation currents cross the mid atlantic ridge preferentially over deep gaps in the ridge demonstrating that sea floor topography can constrain even upper ocean circulation patterns

assessment of trace elements in yercaud lake sediments southern india lake sediments are major sink for carbon and trace elements lake water and sediments need to be monitored continuously for environmental and geochemical explorations in the present study sediment characteristics source and distribution of trace metals fe mn cr cu ni co pb and zn of yercaud fresh water lake sediments south india situated at an elevation of 1515 m asl is presented twenty five surface sediments were collected covering the entire expanse of the lake in a gridded pattern detailed chemical analyses reveal the following decreasing order of elements fe cu cr mn zn ni co pb geoaccumulation index enrichment factor contamination factor and pollution load index were calculated to evaluate the ecological impacts of these trace metals in the sediments the index calculation indicates that all the trace elements were derived from natural process but there are indications of anthropogenic activities the study area was found to be highly contaminated with cu moderately contaminated with cr and co considerably contaminated with pb zn and ni and uncontaminated with mn the spatial distribution of the trace elements supports the strong association of sediment fine fraction and organic matter the statistical principal component analysis also confirms that the concentration of cr cu fe and mn was mainly derived from the natural weathering and non point agricultural sources pb and zn arise due to the confluence of sewage effluents traffic and boat activities these elements need to be further evaluated for pollution control and prohibiting further deterioration in the yercaud lake

occurrence and origin of soils with andic properties in calabria southern italy abstract andic like soils along with andosols have previously been reported in non volcanic ecosystems of the coastal and mountainous areas of the calabria region southern italy but little is known about their properties soil formation processes and volcanic source areas chemical mineralogical microscopic sub microscopic and magnetic analyses were carried out on 8 soils which were selected from the major calabrian geological sectors in order to assess relationships between parent material and bedrock soil chemical properties revealed an occurrence of andic or vitric properties in the studied soils as a whole and the optical microscopy enabled to identify volcanic glass micro pumices and soil isotropic matrix clearly indicating volcanic inputs three groups of soils identified on the basis of the degree of andic properties showed rather homogeneous also in terms of chemical properties clay mineralogy and land use as well as with regard to micromorphology and magnetic susceptibility part of the intra group similarities was a consequence of similar distances between sites and volcanic source area as suggested by the correlations found between ferrihydrite content andic i e of ammonium oxalate extractable al 0 5 fe and phosphate retention and magnetic properties vs distances from several sicilian districts the elemental composition obtained by sem eds analyses of soil glass fragments supported these findings and related the origin of most of the studied soils to the high potassium calc alkaline magmatism of the southernmost eolian islands mainly lipari and vulcano except for soils from the marine terraces of northern calabria pra and the aspromonte massif del which were both linked albeit uncertainly to campanian volcanism soil magnetic properties were significantly 0 79 correlated to the andic properties so confirming the high performance of magnetic susceptibility as low cost proxy for the identification of volcanic constituents

from andic non allophanic to non andic allophanic inceptisols on alkaline basalt in mediterranean climate a toposequence study in the marghine district sardinia italy abstract the properties of a non andic allophanic inceptisol pom1 and two andic non allophanic inceptisols flm5 and spm8 representative of a toposequence on basanite rocks of mt st antonio central western sardinia marghine sub region were analyzed to better elucidate factors and processes that lead to a different expression of andic properties and allophane formation in xeric mediterranean environment a series of laboratory techniques including physical chemical micromorphological x ray diffraction xrd scanning electron microscopy sem analyses were used all soils are usually rich in organic carbon dystric at the great group level with saturation base from 72 to 10 and with ph from subalcaline to acidic allophanic inceptisol appears more intensely weathered than non allophanic inceptisols volcanic glass content is in any case negligible pom1 formed on the plateau shows a shallow solum 45 cm with a 2 horizon that meets all the criteria for andic soil properties the amounts acid oxalate extractable al o and si o together with pyrophosphate extractable al p typifies such a pedon as allophanic inceptisol 0 19 p al o 2 the allophanic inceptisol pom1 is located at the plateau of the toposequence where lower surface runoff greater water infiltration rate the absence of significant erosion and colluvial movement may have increased the degree of weathering processes in these conditions the prolonged soil moistness prevents the transformation of short order components on the whole the results emphasize the role of topography and the importance of al fe amorphous compounds in expressing soil andic properties and allophane content versus the volcanic origin of parent material and the insufficiency of volcanic glass the results also suggest that the occurrence of soil with andic properties and significant allophane content in hot and dry environments like the mediterranean climate in sardinia may be more widespread than expected

magnetic mineralogy of soils across the russian steppe climatic dependence of pedogenic magnetite formation formation of ferrimagnets in well drained buffered unpolluted soils appears to be related to climate and especially rainfall if robust this magnetism rainfall couple can be used to estimate past rainfall from buried soils particularly the multiple soils of the quaternary loess soil sequences of central asia however dispute exists regarding the role of climate vs dust flux for the magnetic properties of modern loessic soils here we examine the mineralogical basis of the magnetism rainfall link for a climate transect across the loess mantled russian steppe where critically dust accumulation is minimal at the present day magnetic and independent mineralogical analyses identify in situ formation of ferrimagnets in these grassland soils increased ferrimagnetic concentrations are associated with higher annual rainfall xrd and electron microscopy show the soil formed ferrimagnets are ultrafine grained 50 nm and pure ferrimagnetic contributions to ma ssbauer spectra range from 17 in the parent loess to 42 for a subsoil sample from the highest rainfall area total iron content varies little but the systematic magnetic increases are accompanied by decreased fe2 content reflecting increased silicate weathering for this region parent materials are loessial deposits topography is rolling to flat and duration of soil formation effectively constant the variations in soil magnetic properties thus predominantly reflect climate and its co variant organic activity statistical analysis identifies strongest relationships between rainfall and magnetic susceptibility and anhysteretic remanence this magnetic response correlates with that of the modern soils across the chinese loess plateau such correlation suggests that the rainfall component of the climate system not dust flux is a key influence on soil magnetic properties in both these regions

characterisation of soils by mineral magnetic measurements processes of iron mineral authigenesis diagenesis and dissolution in interaction with primary inputs of iron minerals act to produce vertical differentiation of soil magnetic properties thus magnetic iron oxides in common with other iron forms may both respond to and reflect soil forming processes investigation of the degree of detectable and persistent magnetic differentiation within different soil materials can provide insights into the nature and direction of distinct sets of soil processes evidence of clear association between magnetic variation and discrete types of soil environment also has applied significance in several areas of environmental study for example the observed magnetic variation can be used to discriminate between individual soils and soil horizons for the purposes of soil surveying sediment tagging and tracing and empirical modelling of source sediment linkages this paper reports the use of mineral magnetic techniques to characterise the iron oxide assemblages within soils of varying type and provenance the effect of different pedogenic regimes have been investigated through measurement of a range of magnetic parameters including magnetic susceptibility frequency dependent susceptibility and anhysteretic and saturation remanences contrary to current pedological thought but in accord with other magnetically based studies e g mullins the presence of magnetite maghemite typically of superparamagnetic single domain grain size within soils has been found to be an extremely widespread phenomenon its contemporary neoformation within the soil environment is inferred however the input of artificially generated ferrimagnetic material is indicated for one of the magnetically enhanced soils examined here and the possibility of extraneous sources of magnetite in topsoils should be considered before pedogenic processes of magnetic enhancement are inferred from the data presented discrimination of industrially derived magnetic particles appears possible on the basis of their very low levels of frequency dependent susceptibility fd low anhysteretic remanence arm and dissociation from the finer clay sized not the formation but the active dissolution of ferrimagnetic minerals is indicated for soils affected by the processes of gleying and podsolisation eluvial horizons of podsolised profiles demonstrate almost total loss of detectable magnetic content variations in the form of the iron reprecipitated in the underlying illuvial layers may reflect differences in the pedological characteristics of these horizons within gleyed waterlogged soils processes of magnetite dissolution appear to be grain size specific preferential reduction of those grains of ultrafine superparamagnetic and fine single domain magnetic grain size is indicated where soil forms a major contributor to catchment sediment loads this has significance in the area of source sediment modelling soil derived from permanently wet or highly leached catchment areas is unlikely to contribute to peaks in the magnetic content of deposited sediments further only those erosional processes that operate at a faster rate than those of magnetic depletion will have the capacity to produce peaks in sediment ferrimagnetic concentrations such as have been observed within the historical magnetic record

how abundant is pedogenic magnetite abundance and grain size estimates for loessic soils based on rock magnetic analyses 1 the upper soil horizons of many modern and ancient soils are enriched in fine grained pedogenic ferrimagnetic minerals we use three grain size and concentration dependent proxies anhysteretic remanent magnetization isothermal remanent magnetization ratios coercivity spectra derived from alternating field demagnetization of saturation isothermal remanent magnetization and hysteresis properties to quantify the abundance and grain size of the pedogenic magnetic component our analyses of modern loessic soils from the midwestern united states show that relatively small additions 2 10 vol of the total ferrimagnetic component of fine grained coarse superparamagnetic to fine pseudosingle domain magnetite or maghemite are sufficient to explain the changes in concentration and grain size dependent properties observed in the upper soil horizons furthermore the pedogenic components of all studied sites display a narrow range of magnetic properties which argues for a common origin of these particles over a wide range of climatic conditions

magnetic and chemical parameters of andic soils and their relation to selected pedogenesis factors in the case of andic soils developed on volcanic rocks permanently humid conditions are essential for andosolisation processes although volcanic rocks are usually rich in highly magnetic iron oxides knowledge about these minerals in andic soils with respect to the soil development is missing the aim of this contribution is to investigate the relationship between magnetic and basic chemical properties of soils developed on volcanic basement and parameters related to the pedogenesis factors the studied sites are located on basaltic lava flows in the eastern part of the french massif central investigated pedons with alu andic sil andic and vitric properties were pedologically described and analysed by a set of magnetic and soil chemical methods magnetic parameters include low field volume specific and mass specific magnetic susceptibility frequency dependent magnetic susceptibility remanent properties including s ratio and coercivities chemical parameters included the phh2o soil organic matter total cation exchange capacity base saturation and content of fe and al extracted in dithionite citrate acid ammonium oxalate and pyrophosphate solutions micro morphology of andosols and parent material was observed by scanning electron microscopy completed with energy dispersive spectrometry the pedogenesis factors are represented by parent rock age annual precipitation and soil thickness our findings suggest that 1 precipitation is the most important pedogenesis factor with a strong relationship to the relative magnetic grain size concentration of ferrimagnetic minerals aluminium dissolved in pyrophosphate and acid ammonium oxalate and content of organic matter 2 parent material age shows a well pronounced relationship with magnetic grain size parameters represented by the frequency dependent susceptibility and ratio of saturation remanent to saturation induced magnetisation mrs ms selective dissolution parameters and phh2o 3 thickness of soil profile shows a link to mrs ms phh2o and content of organic matter

the influence of atlantic sea surface temperature anomalies on the north atlantic oscillation abstract the influence of atlantic sea surface temperature sst anomalies on the atmospheric circulation over the north atlantic sector during winter is investigated by performing experiments with an atmospheric general circulation model these consist of a 30 yr run with observed sst anomalies for the period 1961 90 confined geographically to the atlantic ocean and of a control run with climatological ssts prescribed globally a third 30 yr integration with observed ssts confined to the south atlantic is made to confirm present findings the simulated interannual variance of 500 hpa wintertime geopotential heights over the north atlantic attains much more realistic values when observed atlantic ssts are prescribed circulation patterns that resemble the positive phase of the north atlantic oscillation nao become more pronounced in terms of the leading eof of winter means and a cluster analysis of daily fields the variance of an interannual nao index increases by fivefold over its control value atl

synchrotron based speciation of chromium in an oxisol from new caledonia importance of secondary fe oxyhydroxides in new caledonia the weathering of ultamafic rocks under a tropical climate has led to the residual accumulation of trace elements in lateritic soils widely dominated by fe oxyhydroxides the speciation of trace elements such as cr ni and co in these oxisols remains a major subject of interest regarding mining and environmental issues we have assessed the speciation of chromium in the upper part of an oxisol by combining bulk and spatially resolved chemical analyses epma and sem eds with synchrotron based spectroscopic data exafs and xanes epma indicates that the main hosts for chromium in the bedrock sample are the silicates forsterite enstatite and lizardite hosting of chromium in these easily weatherable mineral species could lead to a significant loss of this element upon weathering however total analyses of major elements indicate only a slight depletion of cr together with an immobility of fe and al and drastic losses of si and mg after the weathering of the bedrock such a low mobility of chromium is likely related to its significant incorporation in goethite and hematite formed after the weathering of fe 2 bearing primary silicates this efficiency of secondary fe oxyhydroxides at immobilizing chromium is demonstrated by quantitative analysis of exafs data that indicates that these mineral species host between 67 and 75 wt of total cr compared to the 18 to 22 wt of total cr hosted by chromite in addition sem observation and sem eds analyses performed on the oxisol samples also show some evidence for chemical weathering of chromite chromite could then represent a past and or present source of chromium upon extended tropical weathering of the studied oxisol rather than a stable host these results emphasize the importance of secondary fe oxyhydroxides compared to cr spinels on chromium hosting in oxisols developed upon tropical weathering of ultramafic rocks although the trapping mechanism of chromium mainly corresponds to incorporation within the structural network of goethite and hematite sorption reactions at the surface of these mineral species could also be involved in such a process in addition considering their potential oxidative reactivity that can generate cr 6 or enhance the chemical weathering of chromite the occurrence of mn oxides could significantly modify the behavior of chromium upon weathering these considerations indicate that further studies are needed to assess the actual potential of chromium release from oxisols developed upon weathering of ultramafic rocks under a tropical climate

signatures of the mediterranean outflow from a north atlantic climatology 2 diagnostic velocity fields part 1 of this study is a descriptive analysis of the spreading of mediterranean water based on high resolution maps of salinity and density in the eastern basin in this second part of our study velocity fields for two representative isopycnal surfaces of the mediterranean outflow o 0 s 29 70 and o 0 s 29 90 are estimated from a diagnostic model that combines climatological hydrographic data from the national oceanic data center with long term direct measurements of water exchange through the strait of gibraltar the model is constrained by geostrophic dynamics conservation of mass no flux conditions at the continental shelf and specified flow through the strait of gibraltar our principal data source is a recently assembled database of the north atlantic that consists of climatological mean property fields averaged on isopycnal surfaces the mean fields are based on more than 80 years 1909 1990 of data and have a nominal horizontal resolution of 0 5 o to provide boundary conditions at the strait of gibraltar we use the results of a model developed from data collected during the gibraltar experiment in 1985 the estimated velocity fields show mediterranean water exiting the strait of gibraltar following the southern iberian coast and then entering the tagus basin where it turns anticyclonically to create a reservoir of this water mass the flow continues northward along the eastern boundary penetrating into the rockall channel finally the model flow fields do not show a significant westward advection of mediterranean waters into the subtropical gyre

assessment of vertical contamination of cd pb and zn in soils around a former ore smelter in wallonia belgium concentrations of trace elements cd co cr cu ni pb and zn and major elements ca mg k fe al and mn as well as phkcl and total organic carbon toc were measured on 22 profiles located in a 3 km radius of a former ore treatment plant in wallonia belgium the enrichment factor ef vertical impoverishment factor vif and availability ratio ar were used as diagnostic tools of contamination and migration of cd pb and zn in profiles the data revealed that the soil profiles are significantly contaminated the ranges of efs for cd 17 3570 pb 1 2883 and zn 2 309 are very broad with the higher ef in the topsoil of the profiles vifs of subhorizons are rarely above 1 in the few cases with vif 1 the main factor explaining is the soil type in particular colluvic regosols luvisols and cambisols with shale load cd pb and zn ars are strongly correlated with toc and to a lesser extent with phkcl pb and zn ars are influenced by soil type while land use only has an effect on zn ar the cd availability is independent of these two factors the contents of trace elements measured in soil profiles are very high especially in topsoil at present the cd pb and zn vertical distribution shows a low migration from topsoil to deeper levels however we must not discount the hazard of a future potential transfer

identification of podzols and podzolised soils in new zealand by relative absorbance of oxalate extracts of a and b horizons abstract a method for separating podzols and podzolised soils from other new zealand soils is proposed the method is based on measurement of the optical density of acid oxalate extracts of soils a number of soil leaching sequences and some individual soils are examined it is assumed that the optical density of the oxalate extracts is due mainly to extracted fulvic acid and that detection of appreciable quantities of this material in the b horizon indicates that podzolisation is an active process in the soil the technique separated the soils of the leaching sequences well following the observable increase of podzolic characteristics with increased leaching when the b horizon a horizon odoe optical density of the oxalate extracts ratios were compared with the criteria for the spodic horizon in soil taxonomy soil survey staff 1975 it was found that all soils with a ratio of less than 1 0 did not satisfy spodic horizon criteria and were not classified as podzol podzolised all the soils examined with ratios 1 0 satisfied spodic horizon criteria or were classified as podzol podzolised usually both

distribution of some selected major and trace elements in four italian soils developed from the deposits of the gauro and vico volcanoes the vertical distribution of 21 elements k ca ti fe mn cr ni cu zn ga as se br rb sr y zr pb th u hg in four italian soils derived from volcanic materials has been investigated most of the elements and in particular lithogenic ones show little enrichment depletion indicating a low degree of weathering and a great similarity to the parent material in relative terms the degree of soil evolution horizon expression and weathering and the depletion of the more mobile elements k ca and sr seem to increase with increasing rainfall and soil age discontinuities in the soil profile due to the accretion of new volcanic material are detectable from the geochemical composition of the horizons some metallic elements such as hg pb cu mn and zn show enrichment in the organic rich horizons o and a but the intensity of enrichment suggests that besides biocycling and weathering processes human activity soil management fertilizing and atmospheric pollution may be significant sources of trace elements

climate dependent chemical weathering of volcanic soils in iceland abstract the major element mobility within soil profiles of brown to gleyic andosols that developed under diverse climatic conditions in iceland is assessed the volcanic soils were selected from areas with good monitoring of annual temperature and precipitation and the degree of weathering and elemental behavior is compared icelandic soils are subject to high fluxes of aeolian dust and at times to tephra ejecta from volcanic eruptions the source of dust input is assessed for each profile based on comparison of the chemical signatures found in the less weathered upper horizons with those of volcanic systems supplying material to source areas results show that tio 2 al 2 o 3 and fe 2 o 3 t and mno are the least mobile species and generally found enriched within more mature horizons the mobile base cations mgo cao and na 2 o are depleted in these horizons as a result of chemical weathering during pedogenesis soils developed in colder climatic conditions with mean annual temperature mat 1 c give values for the chemical index of weathering ciw of 37 45 that reflect only weak chemical weathering soils developed in milder climates mat 2 4 c are more strongly affected by weathering ciw 50 77 the parent material has ciw values of 37 temperature is demonstrated as the dominant variable exerting control on the extent of weathering with only minor mobilization following the incipient near surface weathering stage a robust linear relationship is found between ciw and model mat mat 0 21ciw 8 93 r 2 0 81 this climofunction can deliver proxy climate estimations from volcanic soils and paleosols of basaltic origin in cool to subarctic conditions 2 to 6 c

impact of a convectively forced gravity wave drag parameterization in ncar ccm3 a parameterization of gravity wave drag forced by subgrid scale cumulus convection gwdc proposed by chun and baik is implemented into the national center for atmospheric research community climate model ncar ccm3 and its effect on perpetual january and july climate is investigated the cloud top gravity wave stress is concentrated in the intertropical convergence zone where persistent deep cumulus clouds exist the resultant zonal wind acceleration due to the breaking of convectively forced gravity waves is predominantly found in the tropical lower stratosphere with westerly acceleration above cloud top and easterly acceleration just below it since the parameterized gravity waves are stationary relative to convective clouds wave breaking occurs mainly in the tropical lower stratosphere where the zonal wind is weak enough for wave saturation it is shown that the gwdc parameterization significantly alleviates the systematic model biases of zonal mean zonal wind and temperature in particular excessive easterlies in the tropical stratosphere and excessive cold temperatures in the tropical lower stratosphere are reduced by more than 50 by including the gwdc parameterization the horizontal wind divergence field in the tropical upper troposphere and lower stratosphere is also significantly improved with the gwdc parameterization the impact of the gwdc parameterization extends to mid to high latitudes through planetary wave activity in the winter hemisphere the increased amplitude of zonal wavenumber 3 in the january northern hemisphere and the increased amplitude of zonal wavenumber 2 in the july southern hemisphere lead to significant improvements in model performance the impact of the gwdc parameterization on eliassen palm ep flux divergence forcing by stationary waves is generally opposite to that by transient waves in the extratropics especially in the northern hemisphere wintertime hence the zonal mean zonal wind change by the gwdc parameterization occurs mainly in the tropics by direct gravity wave drag forcing

andosols in germany pedogenesis and properties abstract soils conforming to andosols in the world reference base wrb of soil resources have not yet been recognised in germany the aims of this study were to i show whether some german soils developed in volcanic parent materials are andosols ii investigate their pedogenetic development and iii determine their local distribution we selected a soil on quaternary basalt in the eifel region the windsborn profile and a soil from the summit of the tertiary basaltic stratovolcano vogelsberg the kohlerwald profile northwest of frankfurt am main the windsborn soil is classified as a silic andosol allophane contents are near 10 and allophane globules were identified by transmission electron microscopy tem by progressively constraining field parameters in gis generated maps we found that andosols in the mosenberg chain are confined to a few isolated occurrences the kohlerwald profile in the tertiary vogelsberg is an acid base poor and strongly weathered aluandic luvisol metal humus complexes are the dominant colloidal phase in the topsoil both fep and alp are in excess of feo and alo values our data suggest the presence of phases like hydroxy al e g from al interlayers or poorly ordered gibbsite and opaline silica that are easily attacked by the alkaline ph 9 5 10 5 pyrophosphate extractant but may be resistant to the acid ph 3 oxalate procedure we conclude that there are limited occurrences of silandic andosols in the eifel area germany the windsborn soil is in an early pedogenetic development stage but pedogenesis in the kohlerwald soil has advanced beyond the andosol phase to the stage of clay translocation therefore the existence of aluandic andosols in germany seems possible but remains to be proven

exchange through the strait of gibraltar to measure the exchange between the atlantic and mediterranean through the strait of gibraltar an array of current meter moorings was deployed for a year in the strait during 1985 1986 a novel aspect of these measurements is the inclusion of conductivity as well as temperature and pressure sensors on each current meter so that the salinity of the flows could be monitored continuously these salinity measurements determine the water mass characteristics of the flows crossing the sill they allow definition of the 37 psu isohaline as the interface between inflowing fresher atlantic water and outflowing saltier mediterranean water and they enable time series to be developed for the depth of this interface for the upper layer inflow and for the lower layer outflow from these measurements the time averaged outflow of mediterranean water is estimated to be 0 68sv 1sv 1 106m3s 1 and the outflow salinity transport defined to be the outflow times the salinity excess above a basic atlantic water salinity of 36 1 psu is estimated to be 1 50 103m3s 1 1sv 1psu 1 103m3s 1 equivalent to a net evaporation over the mediterranean basin of 52cm y 1 extrapolated measurements of the inflow from current meters generally deployed below 100m depth yield an estimate for the time averaged inflow of 0 93sv which is believed to be unrealistically high in view of the better measured outflow and net evaporation thus a more realistic estimate of the inflow is 0 72sv equal to the sum of the outflow and net evaporation as required by the mass budget for the mediterranean sea such estimates of the exchange are smaller by almost a factor of 2 than previous values for the exchange by lacombe and richez 1982 the exchange across the gibraltar sill is found to be due in nearly equal parts to the mean currents and to the tidal fluctuations the mean currents are smaller than had been expected reaching a peak value of only about 60 cm s 1 in the deep outflow over the sill the tidal exchange is due to a strong correlation over the tidal period between the depth of the interface and the strength of the inflowing currents for the m2 tide at the sill the amplitude of the interface depth is 51 m and the amplitude of the tidal currents is 1 2m s 1 furthermore the inflow and interface depth have similar phases as a consequence the upper layer is deep on the inflowing tide so that a large slug of atlantic water crosses the sill into the mediterranean on the outflowing tide the interface is shallow so that a large slug of mediterranean water crosses the sill into the atlantic similar processes occur for the s2 o1 and k1 tides though the amplitude are smaller in this manner tidal oscillations lead to a time averaged exchange of water masses across the gibraltar sill the inflow and outflow defined to be the instantaneous transports above and below the 37psu isohaline interface exhibit m2 tidal amplitudes of 2 3 sv and 1 3sv respectively thus the tides are large enough to reverse the mean upper layer inflow and lower layer outflow daily averaged inflow and outflow transports exhibit low frequency fluctuations with standard deviations of 0 37sv and 0 22sv respectively such low frequency fluctuations have been shown previously to be associated with barotropic flows through the strait of gibraltar compensating for sea level variations over the mediterranean due to atmospheric pressure fluctuations candela winant and bryden 1989 finally from these measurements there appear to be little fortnightly or annual period fluctuations in the exchange through the strait of gibraltar

physical chemical and sedimentological aspects of the mediterranean outflow off iberia a multidisciplinary study of the mediterranean outflow in the region west of the strait of gibraltar and off the southern and southwestern coasts of the iberian peninsula was developed in the frame of the canary islands azores gibraltar observations project two high resolution ctd surveys which included water sampling for chemical nutrients and dissolved oxygen and sedimentological analyses took place in september 1997 summer cruise and january 1998 winter cruise in the study region the correspondence between the high salinity mediterranean water mw layer and the low nutrient content and relatively high abundance of particles was a general result further details of the thermohaline analysis and of the geostrophic computations especially for the layer of mw are compared with the results obtained for the chemical properties and the sedimentological characteristics

momentum and energy balance of the mediterranean outflow field data taken in the gulf of cadiz have been analyzed to describe some aspects of the momentum and energy balance of the mediterranean outflow a crucial component of the momentum balance is the total stress entrainment stress and bottom drag which has been estimated from a form of the bernoulli function evaluated from density and current observations for the first 60 km west of the camarinal sill the outflow was confined within a narrow channel on the continental shelf at about 70 km downstream the outflow crossed over the shelf slope break and began to descend the continental slope the buoyancy force increased substantially and the outflow underwent a geostrophic adjustment albeit one heavily influenced by mixing and dissipation the current direction turned 90 degrees to the right at a near inertial rate in this region the estimated geostrophic velocity greatly underestimated the actual current and the estimated curvature rossby number was about 0 5 current speeds were in excess of 1ms 2 1 and the total stress was as large as 5 pa the entrainment stress estimated independently from property fluxes reached a maximum of about 1 pa or considerably smaller than the inferred bottom stress by about 130 km downstream the current was aligned approximately along the local topography the current amplitude and the estimated stress were then much less about 0 3 m s21 and 0 3 pa the entrainment stress was also very small in this region well downstream of the strait this slightly damped geostrophic flow continued on to cape st vincent where the outflow began to separate from the bottom bottom stress thus appears to be a crucial element in the dynamics of the mediterranean outflow allowing or causing the outflow to descend more than a kilometer into the north atlantic in the regions of strongest bottom stress the inferred drag coefficient was about 2 2 12 3 10 23 depending upon which outflow speed is used in the usual quadratic form entrainment stress was small by comparison to the bottom stress but the entrainment effect upon the density anomaly was crucial in eroding the density anomaly of the outflow the observed entrainment rate appears to follow roughly a critical internal froude number function

signatures of the mediterranean outflow from a north atlantic climatology 1 salinity and density fields using historical data from the national oceanic data center the climatology of the eastern north atlantic basin has been investigated for the purpose of detailing the mediterranean outflow water in terms of its salinity density and flow patterns part 1 of this work is a descriptive analysis of the fate of the mediterranean water once it flows out of the strait of gibraltar tracing the salinity and density signatures high resolution maps of the climatological outflow are presented with an emphasis on the continuity of the water from its source from the climatological fields a continuous signal of mediterranean water is tracked northward to 50 20 n yet its westward advection is limited to the tagus basin recirculations of mediterranean water in the gulf of cadiz and in the bay of biscay deduced from property signals are also detailed iorga and lozier this issue present absolute velocity fields from a diagnostic model constrained by geostrophic dynamics conservation of mass and no flux boundary conditions

deep water circulation in the luzon strait deep water circulation in the luzon strait which connects the pacific deep circulation with the south china sea throughflow is investigated using a set of oceanographic observations combined with results from three numerical experiments both the in situ observations and the model show a deep water overflow in the luzon strait their results suggest that the deep pacific water first flows into the luzon strait through the bashi channel 1 2 sv 1 sv 1 106 m3 s 1 and the taltung canyon 0 4 sv then turns southward along the luzon trough and finally enters the south china sea primarily through two gaps in the heng chun ridge overall the mean transport of the luzon strait overflow is about 1 5 sv results from numerical experiments suggest that strong diapycnal mixing in the south china sea and luzon strait which sustains the baroclinic pressure gradient across the luzon strait is the primary driving mechanism of the deep circulation in the luzon strait

refractory element mobility in volcanic soils refractory trace element concentrations in strongly weathered hawaiian soils ranging in age from 20 to 4100 ka are highly elevated over parent rock values due to extensive mass loss of more soluble major elements during pedogenesis nb and ta exhibit virtually no mobility soil nb ta ratios are within the range of fresh bedrock even when soil nb concentrations are residually enriched by a factor of 10 in contrast al zr and hf are depleted relative to nb in surface soil horizons but are enriched at depth clearly indicating mobility of these elements variations in th nb ratios in soil profiles indicate significant th mobility within the soil column however mass balance calculations require that accretion of th enriched asian dust has resulted in a net increase in th in some soils soils developed on a 150 ka rainfall gradient show that the mobility and loss of zr increase with mean annual precipitation

chromium and copper in micromorphological features and clay fractions of volcanic soils with andic properties abstract in volcanic soils of the solofrana valley south western italy contamination by cr and cu occurs as a consequence of agricultural practices and surface deposition of polluted river sediments by periodic floods in this study the metal distribution in micromorphological features and clay fractions 1 both cr and cu are present in the subsurface infillings with concentrations of 273 and 243 mg kg 1 in deeper horizons the fragments of stratified fine textured alluvial deposits incorporated in the soil matrix contain low concentrations of both metals 13 63 mg kg 1 for cr and 18 24 mg kg 1 for cu suggesting that cr and cu migration in colloidal or ionic form is restricted to a limited distance the contribution of the clay fraction

stress on the mediterranean outflow plume part ii turbulent dissipation and shear measurements abstract bottom and interfacial stresses on the mediterranean outflow plume are estimated using vertical profiles of turbulent dissipation and velocity collected in the gulf of cadiz turbulent dissipation is high throughout the plume with a local minimum often present near the plume nose depth of maximum downstream velocity bottom stresses are estimated by applying a log layer model to the dissipation measurements the dissipation measurements are also divided by plume scale vertical shear from the horizontal velocity profiles to construct profiles of stress within the plume the mean stress estimates in the bottom layer agree well with those calculated in the log layer from the dissipation measurements alone the bottom layer means are slightly larger than those of the interfacial layer the maximum stresses in each layer are uncertain since they depend on the ill defined shape of the stress profiles within the plume dissipation derived stress estimates in the log layer and those from dissipation

rock magnetic properties of eemian maar lake sediments from massif central france a climatic signature the hypothesis of a climate variability within the last interglacial eemian suggested by oxygen isotope data of a greenland ice core grip was later supported by magnetic susceptibility organic matter and pollen signatures in the eemian lake sediments of the lac du bouchet france in the present paper we analyse in detail the rock magnetic properties of these sediments in order to determine the origin of the magnetic susceptibility variations furthermore in order to verify the empirical relation between magnetic susceptibility and climate we studied two eemian sequences from neighbouring lakes lac st front and ribains maar lake rock magnetic investigations mainly consisted of analyses of anhysteretic and isothermal remanent magnetizations along with hysteresis measurements carried out on pilot samples lac du bouchet susceptibility variations are at least partly affected by postdepositional magnetite dissolution lac st front sediments show a complex behaviour resulting in partly contradicting interpretations of rock magnetic parameters possible explanations may be the presence of a very fine grained magnetite or the presence of maghemite ribains maar lake sediments show a homogeneous magnetic mineralogy without major variations in most of the rock magnetic parameters susceptibility records of the three lakes were compared under the simplified assumption that magnetic susceptibility mainly reflects variations of the detrital titano magnetite input only a poor correlation between the three eemian susceptibility sequences is observed suggesting that local effects including dissolution and dilution effects may have altered the original detrital climatic signal the purely detrital origin of the lac du bouchet eemian susceptibility variations must thus be questioned but it nevertheless appears to be the only lake whose susceptibility variations can tentatively be correlated with the grip eemian oxygen isotope record

mediterranean outflow mixing and dynamics the mediterranean sea produces a salty dense outflow that is strongly modified by entrainment as it first begins to descend the continental slope in the eastern gulf of cadiz the current accelerates to 1 3 meters per second which raises the internal froude number above 1 and is intensely turbulent through its full thickness the outflow loses about half of its density anomaly and roughly doubles its volume transport as it entrains less saline north atlantic central water within 100 kilometers downstream the current is turned by the coriolis force until it flows nearly parallel to topography in a damped geostrophic balance the mixed mediterranean outflow continues westward slowly descending the continental slope until it becomes neutrally buoyant in the thermocline where it becomes an important water mass

volcanic soils of iceland abstract the parent materials of all icelandic soils are volcanic in origin and most of the soils are classified as andosols iceland has the largest area of andosols in europe and may have 5 of all andosols in the world a new classification scheme based on the world reference base world reference base for soil resources world soil resources reports 84 fao rome is used to provide an overview of icelandic volcanic soils the data were acquired as part of a recently initiated effort to build a database for icelandic soils but are also partly based on data from the eu cost 622 action a literature review and unpublished icelandic research the main soil types in iceland are histosols histic andosols gleyic andosols brown andosols vitrisols and leptosols in the icelandic language a single term is used to refer to each soil type this system reflects the dominant influence of eolian deposition and drainage conditions on the formation of histosols and andosols the parent materials of icelandic soils are mixtures of tephra layers and eolian sediments consisting mostly of volcanic glass the steady flux of eolian sediments from unstable sandy deserts constantly recharges the surface with basaltic tephra materials the histosols 20 c have appreciable amounts of andic materials because of the eolian deposition the andosols histic gleyic and brown andosols show characteristic properties of soils dominated by andic materials with allophane contents of up to 30 ferrihydrite commonly accounts for 5 15 of the soil the contents of both allophane and ferrihydrite generally decrease with increasing organic c content of soil horizons as organic matter inhibits allophane formation and iron tends to become reduced and lost in poorly drained locations the vitrisols are soils of desert surfaces with low organic content but they usually meet criteria for andic materials with 30 glass and al 1 2fe o 0 4 cryoturbation is intense in iceland resulting in a range of geomorphic surface features the cryoturbation is related to both climatic factors and the andic soil properties including high water retention and rapid hydraulic conductivity

a new parameterization for entrainment in overflows abstract dense overflows entrain surrounding waters at specific locations for example sills and constrictions but also along the descent over the continental slope the amount of entrainment dictates the final properties of these overflows and thus is of fundamental importance to the understanding of the formation of deep water masses even when resolving the overflows coarse resolution global circulation and climate models cannot resolve the entrainment processes that are often parameterized a new empirical parameterization is suggested obtained using an oceanic and laboratory dataset which includes two novel aspects first the parameterization depends on both the froude number fr and reynolds number of the flow second it takes into account subcritical fr 1 entrainment a weak but nonzero entrainment can change the final density and consequently the depth and location of important water masses in the open ocean this is especially true when the dense current follows a long path over

interaction between the orography induced gravity wave drag and boundary layer processes in a global atmospheric model 1 this study investigates the behavior of the orographic gravity wave drag gwdo processes induced by sub grid scale orography in response to the representation of boundary layer mixing in a global atmospheric model the sensitivity of simulated climatology to the representation of stable boundary layer sbl processes associated with gwdo processes in the modeled atmosphere is investigated using the kim arakawa gwdo parameterization scheme it is found that the impact of the boundary layer structure is pronounced in the upper atmospheric circulations above the tropopause through the interaction between the boundary layer mixing and gwdo processes even though the direct impact of the sbl structure is confined to near surface layer this finding reinforces the notion that the success of a particular physics parameterization scheme in atmospheric models relies heavily on the interaction of a physical process with another which should be properly considered in developing physics parameterization schemes for atmospheric models

magnetic viscosity of tropical soils classification and prediction as an aid for landmine detection summary electromagnetic induction emi based metal detectors are the most widely used sensing techniques in landmine clearance operations however they are negatively influenced by frequency dependence of magnetic susceptibility a total of 466 rock and soil samples collected from across the tropics are investigated in this study the data show that frequency dependent susceptibility depends on the parent material as well as on the degree of weathering ultramafic and mafic rocks and their derivatives have higher susceptibility and absolute frequency dependence than material originating from intermediate felsic and sedimentary rocks within each parent material group absolute frequency dependence increases steadily with increasing alteration from unweathered rock to topsoil this effect is likely due to either the residual enrichment of weathering resistant ferrimagnetic minerals including superparamagnetic sp grains the comminution of larger ferrimagnetic minerals or the neoformation of sp minerals during soil formation relative frequency dependence is generally lower than 15 per cent for the investigated samples with a few exceptions it increases with alteration for igneous rocks but remains at the initially high level for sediments this finding indicates that the relative concentration of sp minerals changes with respect to the total magnetic fraction for igneous rocks but remains constant for sediments soils derived from ultramafic mafic and intermediate rocks show low relative frequency dependence and their magnetic susceptibility is mainly the result of multidomain lithogenic minerals in contrast soils derived from felsic rocks and sediments show the highest values and their susceptibility is due to sp minerals that are either formed during pedogenesis or residually enriched theaverageandextremevaluesoftheabsolutefrequencydependencewithineachsubgroup based on parent material and alteration grade are used to design a prognosis system for assessing the impact of the subsurface on emi sensors for landmine detection in general intermediate felsic and sedimentary rocks have no influence on the detectors and only a weak influence inthemostextreme cases soilsderived fromtheserockstypically have noinfluence however they can have a very severe influence in a few cases in contrast ultramafic and mafic rocks typically have a moderate influence and a very severe influence in extreme cases with the associated soils resulting in a severe influence in general the deduced prognosis system can be used by demining organizations to help them predict metal detector performance in tropical regions on the basis of geologic and or soil maps which do not supply information on electromagnetic properties in this way such a system may eventually help with the planning of demining campaigns and selection of appropriate sensors

a normalised intensity record from lac du bouchet geomagnetic palaeointensity for the last 300 kyr a normalised intensity record has been obtained from 2500 sediment samples taken from three cores of length 50 m from lac du bouchet a small maar crater lake in the massif central of france the sediment sequence has been dated by14c in the top 40 kyr by correlation of the pollen derived climatic stratigraphy with the marine 18o stratigraphy and byar ar ages 275 7 kyr for a tephra interbedded at 43 m depth the sediments are mainly detrital and fall into two broad sediment types silty clays 83 of the total deposited under glacial climatic conditions with high titanomagnetite concentrations 0 5 1 by weight and compacted gyttjas organic rich clays deposited under warmer conditions with a more variable magnetic mineralogy of lower concentration normalisation of the nrm by susceptibility arm and sirm yields palaeointensity records that are similar to each other but bear little resemblance to the normalisor records sirm gives the best results of the three however the compacted gyttjas give consistently low palaeointensity values and high palaeointensities correspond to high sirm arm ratios which occur during the full glacials of 18o stages 2 and 6 normalisation has incompletely removed lithological and climatic factors from the nrm to overcome this we have attempted a secondary normalisation by weighting the palaeointensity values according to a least squares fit to the sirm arm resulting in an improved palaeointensity estimate the average accumulation rate of 15 cm kyr together with the close sampling interval gives a palaeointensity record of much greater resolution than most published palaeointensity records

mineralogical and magnetic characterisation of iron titanium oxides in soils developed on two various basaltic rocks under temperate climate abstract the objective of this study was to characterize alteration processes of iron titanium oxides in andic soils developed on basaltic rocks under temperate climate among the magnetic minerals titanomagnetites are the most abundant and represent the major spinel in basalts in order to understand processes involved in the alteration of iron titanium oxides from basaltic rocks associated to soils two pedons developed on tertiary massive basaltic formations submitted to temperate climate were considered the magnetic minerals have been characterized by studying rock and soil magnetic parameters i e magnetic susceptibility and curie temperature chemical composition was investigated by optical and electron microscopy empa sem eds and by micro proton induced x ray emission pixe because mineralogy of the parent rocks controls those of the soils we have first studied the rocks the thermomagnetic curves obtained on the two studied rocks show that initial titanomagnetite is preserved in one sample mc rock while the other pc rock contains near pure magnetite possibly issued from exsolution process microscopic observations confirm the exsolution lamellae on titanomagnetites and show a cr content gradient in chromian spinel partially enclosed in olivine these observations suggest a deuteric alteration the two profiles exhibit increasing curie temperature between the rocks and soil horizons indicating a transformation of magnetic minerals results emphasize the maghemitization of iron titanium oxides in andic soils in a temperate climate

lagrangian observations of meddy formation during a mediterranean undercurrent seeding experiment mediterranean eddies meddies play an important role in maintaining the temperature and salinity distributions in the north atlantic but relatively little is known about their early life histories including where how often and by what mechanism they form a major field program called a mediterranean undercurrent seeding experiment has been carried out to directly observe meddy formation and the spreading pathways of mediterranean water into the north atlantic between may 1993 and march 1994 49 rafos floats were deployed sequentially in the mediterranean undercurrent south of portugal and tracked acoustically for up to 11 months the float deployments were accompanied by high resolution xbt sections across the undercurrent nine meddy formation events were observed in the float trajectories six near cape st vincent at the southwestern corner of the iberian peninsula and three near the estremadura promontory along the western portuguese continental slope meddy formation thus occurs where the continental slope turns sharply to the right when facing in the downstream direction of the undercurrent after conditionally sampling the float dataset to identify floats that were well seeded in the undercurrent the authors have estimated a meddy formation rate of 15 20 meddies per year the timescale for meddy formation at cape st vincent was found to be 3 7 days shorter than previous estimates based on the volume of larger meddies meddies were observed to form most frequently when the speed of the mediterranean undercurrent was relatively fast the meddy formation process at cape st vincent resembles the conceptual model of e a d asaro whereby anticyclonically rotating eddies are formed by separation of a frictional boundary layer with negative relative vorticity at a sharp corner comparison of the relative vorticity in the anticyclonic shear zone of the undercurrent and that of the newly formed meddies shows that much of the anticyclonic relative vorticity in meddies can be accounted for by the horizontal shear in the undercurrent this confirms earlier work suggesting that the classical mechanism for the generation of submesoscale coherent vortices by collapse and geostrophic adjustment of a weakly stratified fluid injected into a stratified ocean may not be the principle mechanism at work in the formation of meddies at cape st vincent

geochemical evolution of a palaeolaterite the interbasaltic formation northern ireland abstract the interbasaltic laterites of northern ireland were formed during a period of relative volcanic inactivity by extensive chemical weathering of tertiary basalts they reach a maximum thickness of 30 m and once provided a major source of iron and aluminium ore an extensive database comprising major minor and trace elements has been compiled for 240 samples in order to study the effects of weathering in terms of the changes in whole rock chemistry and mineralogy from basalt through to iron rich crust percolating waters caused degradation of the parent basalt mineralogy and precipitation of neoformed phases principally through incongruent dissolution processes primary olivine plagioclase feldspar and augite were successively broken down and replaced by a mineral assemblage consisting of hematite gibbsite goethite anatase meta halloysite and kaolinite changes in mineralogy facilitated concomitant changes in element concentrations mass balance calculations indicate that all elements were depleted in the iron crust enrichment of al loi cr cu and v occurred in the laterite horizon while enrichment of al loi ba ce cr cu ni and rb occurred in the lithomarge notably yttrium was found to be mobile indicating that weathered basalts should not be used in discrimination of original tectonic environments the severe leaching conditions evidenced by yttrium depletion local aluminium redistribution and iron crust formation are indicative of weathering under a humid sub tropical monsoon climate

geochemical normalization of magnetic susceptibility for investigation of floodplain sediments magnetic susceptibility ms is commonly used as a proxy for industrial pollution in natural sediments or as a proxy for the percentage of detrital components in peat or carbonates the ms may also reflect the geology of the sediment source and post depositional processes in sediments such as soil development the aim of our research was to test the usefulness of fe normalized mass specific ms and ti normalized fe in a study of floodplain sediments we sampled 27 floodplain sediment cores from several geologically different catchments throughout the czech republic analysed their fe and ti concentrations using x ray fluorescence spectroscopy and determined their to decipher sediment grain size dependence and possible magnetic enrichment background functions for were constructed using similar approach as that used for geochemical background functions of the risk element concentrations with fe concentrations as an independent variable it provides a mechanism to calculate of sediments as it would be pristine i e without post depositional changes and pollution sediments derived from mafic source rocks had fe larger by two orders of magnitude than sediments derived from felsic rocks sediments derived from mafic source rocks also exhibit lower mean fe ti ratio in pristine sediment strata than the average upper continental crust the magnetic carriers inherited from mafic rocks are stepwise destroyed by pedogenesis in the floodplains and thus slowly approach of sediments derived from felsic rocks gleying processes may change fe fe ti ratio allows identifying a past action of those post depositional processes

quantifying multiple electromagnetic properties in emi surveys a case study of hydromorphic soils in a volcanic context the lac du puy france we used two different loop loop electromagnetic induction emi devices to determine the 3d geometry and morphology of the pedo sedimentary filling and underlying basaltic bedrock of a former wetland in a volcanic soil area the lac du puy depression auvergne france electrical conductivity or resistivity is usually sufficient for environmental and soil science applications but the local volcanic context of the survey area results in high values of magnetic susceptibility and possible electrical polarization effects therefore we investigated the roles of the four properties electrical conductivity magnetic susceptibility magnetic viscosity and dielectric permittivity we created models using these four properties for the two coil configurations of each device in order to assess the degree to which each of the properties contributed to the recorded electromagnetic signal the results show that electrical conductivity controls the quadrature component of the secondary field response but that it can be affected by high values of magnetic viscosity while magnetic susceptibility controls the in phase component moreover the low frequencies imply a limited contribution of dielectric permittivity to the in phase component except in the cases of higher permittivity or frequency values or greater inter coil separation based on these observations we propose a way to map the apparent properties from field measurements we then carried out a 1d inversion first by considering the electrical conductivity alone and secondly by taking all the electromagnetic properties into account the results show that there is a marked contrast in the complex magnetic susceptibility between the sedimentary in fill and the border of the lac de puy depression stronger than for the electrical conductivity and that permittivity is unlikely to have a significant influence the shape and nature of the sedimentary in fill was thus considerably refined by the second inversion results based on the three other properties these data combined with litho stratigraphic observations from a previous study allowed the lateral continuity and geometry of the in fill to be assessed across the whole basin results are also consistent with previous interpretations of the depression as a pseudo sinkhole a relatively common morphology in volcanic plateaus analysis of the magnetic properties also made it possible to characterize the spatial variation of some key features related to hydromorphic processes such as clayey granularity and the development of iron oxides hydroxides this opens up the possibility for using new methods for rapid spatial and pedological characterization of hydromorphic soils and palaeosoils

on the reasons for the formation and variability of the azores current abstract recent studies have shown that the formation of the well defined zonally oriented azores current may be the result of water mass transformation associated with the mediterranean outflow in the gulf of cadiz as the denser mediterranean water descends down the continental slope it entrains overlying north atlantic central water it is believed that the azores current then forms as part of the horizontal recirculating gyre generated through the plume mechanism in this study the authors further explore this hypothesis by performing a series of numerical experiments these experiments are based on a high resolution general circulation model that includes the mediterranean sea and that realistically simulates the water mass exchange through the strait of gibraltar and the transport and variability of the azores current the authors show that the divergence of the relative vorticity flux and the planetary vorticity flux associated with planetary waves are the main factors determining the variab

on the connection between the mediterranean outflow and the azores current as the salty and dense mediteranean overflow exits the strait of gibraltar and descends rapidly in the gulf of cadiz it entrains the fresher overlying subtropical atlantic water a minimal model is put forth in this study to show that the entrainment process associated with the mediterranean outflow in the gulf of cadiz can impact the upper ocean circulation in the subtropical north atlantic ocean and can be a fundamental factor in the establishment of the azores current two key simplifications are applied in the interest of producing an economical model that captures the dominant effects the first is to recognize that in a vertically asymmetric twolayer system a relatively shallow upper layer can be dynamically approximated as a single layer reduced gravity controlled barotropic system and the second is to apply quasigeostrophic dynamics such that the volume flux divergence effect associated with the entrainment is represented as a source of potential vorticity two sets of computations are presented within the 1 layer framework a primitive equation based computation which includes the divergent flow effects is first compared with the equivalent quasigeostrophic formulation the upper ocean cyclonic eddy generated by the loss of mass over a localized area elongates westward under the influence of the b effect until the flow encounters the western boundary in the steady state the circulation pattern consists of bidirectional zonal flows with a limited meridional extent eastward to the south of the sink and westward to the north of the sink the localized sink drives a horizontal circulation in the interior ocean whose strength is approximately an order of magnitude greater than the sink s strength it is demonstrated that the induced circulation in the far field from a localized sink is insensitive to the neglect of the divergent flow component a set of parameter sensitivity experiments is then undertaken with the quasigeostrophic model for an idealized midlatitude circulation driven both by wind forcing and thermohaline flow through the open southern and northern boundaries when a sink near the eastern boundary is superimposed on the idealized midlatitude circulation it is shown to alter significantly the upper ocean flow and induce an eastward zonal current which resembles the azores current in location and transport this mechanism also generates a westward current to the north of the sink location which could be associated with the azores countercurrent an extensive series of sensitivity experiments is conducted to determine the response of this current system to changes in the boundary layer processes sink strength sink distribution model resolution and wind forcing the magnitude of the current transports is found to be sensitive to the sink intensity and to its distance from the coastline

volcanic soils of france abstract in france andic soils mainly occur in the massif central andic and other volcanic soils 5000 km 2 and on the vosges and the morvan hercynian massifs in the massif central silandosols on recent pyroclastics are distinguished from aluandosols on older mio pliocene lavas after a brief introduction to the parent materials soil characterisation survey genesis properties and land use are reviewed in two periods from 1960 to 1979 and from 1980 to 2000 soil distribution is related schematically to topo climatic sequences comparing recent pyroclastics to older volcanic lavas an udic or perudic soil moisture regime is the primary factor in andosol genesis in france silandosols occur only on recent pyroclastics and aluandosols on old lavas after reworking by glacial erosion from a mantle of loose and pre weathered materials the anthropic impacts include accelerated erosion and changes in carbon content

magnetic properties of modern soils and quaternary loessic paleosols paleoclimatic implications the magnetic properties of paleosols developed in quaternary sequences of loess have been used for stratigraphic definition correlation with other terrestrial and deep sea sequences and paleoclimatic paleorainfall reconstruction in some loess paleosol sequences including those of the chinese loess plateau tajikistan and the czech republic maxima in magnetic susceptibility values correspond with the paleosol horizons and minima with the least weathered loess layers in other loess soil sequences including those of siberia alaska and argentina the relationship is completely opposite with susceptibility minima associated with the most developed paleosols to account for these opposite relationships the respective roles of 1 magnetic enhancement and 2 magnetic depletion and or dilution in determining soil magnetic properties are investigated for a range of modern soil types most magnetic enhancement is seen in the upper horizons of well drained cambisols absence or loss of magnetic iron oxides is apparent in acid podsol profiles and waterlogged soils for the cambisol profiles significant correlation is found between susceptibility and organic carbon cation exchange capacity and clay content the mineralogy morphology and grain size of soil magnetic carriers extracted from three modern enhanced soils and a paleosol from the chinese loess plateau are also identified by independent petrographic means microscopy and x ray diffraction of magnetic extracts magnetite and maghemite of ultrafine grain size from 0 4 to 0 001 i m are the major contributors to the magnetically enhanced soils weathering can concentrate detrital magnetic grains especially in the fine silt size fractions of soils the magnetic data from the modern soils indicate that interpretation of paleosol magnetic properties must be done on a site specific basis taking into account the possibilities of pedogenic enhancement pedogenic dilution or depletion and allochthonous inputs of magnetic minerals excessively arid wet or acid soils are unable to form significant amounts of pedogenic ferrimagnets well drained intermittently wet dry soils with reasonable buffering capacity and a substrate source of fe show most magnetic enhancement for those soils which favour magnetic enhancement processes correlation has been found between the maximum value of the pedogenic susceptibility and the annual rainfall the almost unique pedogenic system in the chinese loess plateau where variation in soil forming factors other than climate is reduced to a global minimum allows use of the paleo susceptibility values as proxy paleorainfall values to identify the mechanism of any link between magnetic properties for example susceptibility and climate change the mineralogy and grain size of soil magnetic carriers requires detailed investigation given the prospect of 1 quantitative paleorainfall records from continental loess records 2 predictions of present and future climate change and 3 the value of paleoclimate data for testing of numerical climate models such magnetic investigations can contribute significantly to our understanding of past and future environmental change

mixing and spreading of the mediterranean outflow abstract hydrographic and current profiler data taken during the 1988 gulf of cadiz expedition have been analyzed to diagnose the mixing spreading and descent of the mediterranean outflow the s properties and the thickness and width of the outflow were similar to that seen in earlier surveys the transport of pure mediterranean water i e water with s 38 4 psu was estimated to be about 0 4 106 m3 s 1 which is lower than historical estimates most of which were indirect but comparable to other recent estimates made from direct velocity observations the outflow transport estimated at the west end of the strait of gibraltar was about 0 7 106 m3 s 1 of mixed water and the transport increased to about 1 9 106 m3 s 1 within the eastern gulf of cadiz this increase in transport occurred by entrainment of fresher north atlantic central water and the salinity anomaly of the outflow was consequently reduced the velocity weighted salinity decreased to 36 7 psu within 60 km of the strait and decre

representation of subgrid scale orographic effects in a general circulation model part i impact on the dynamics of simulated january climate abstract effects of subgrid scale orography are represented in most large scale models of the atmosphere by means of parameterizing subgrid scale orographic gravity wave drag and or enhancing grid scale orography such as envelope orography with the use of subgrid scale orographic variance a new gravity wave parameterization scheme and an envelope orography have been implemented in the ucla general circulation model the impact of gravity wave drag and envelope orography on simulations using the tropospheric stratospheric 15 layer version of the model are briefly discussed and compared the gravity wave parameterization scheme and the envelope orography have a qualitatively similar and beneficial impact on ensemble means of simulated january climate the midlatitude westerlies are weakened at all levels and the polar atmosphere is warmed in the northern hemisphere a combination of the two produces the best results sensitivity experiments with the parameterization scheme indicate the importance of th

tracking the mediterranean outflow in the gulf of cadiz abstract the mediterranean water leaves the western end of the strait of gibraltar as a bottom wedge of salty and warm waters flowing down the continental slope the salinity of the onset mediterranean outflow water mow is so high that leads to water much denser initially in excess of 1 5 kg m 3 than the overlying central waters during much of its initial descent the mow retains large salinity anomalies causing density anomalies that induce its gravity current character and relatively high westward speeds causing a substantial coriolis force over long portions of its course we use hydrographic data from six cruises a total of 1176 stations plus velocity data from two cruises together with high resolution bathymetric data to track the preferential mow pathways from the strait of gibraltar into the western gulf of cadiz and to examine the relation of these pathways to the bottom topography a methodology for tributary systems in drainage basins modified to account for the coriolis force emphasizes the good agreement between the observed trajectories and those expected from a topographically constrained flow both contour avenues and cross slope channels are important and have complementary roles steering the mow along the upper and middle continental slope before discharging as a neutrally buoyant flow into the western gulf of cadiz our results show that the interaction between bottom flow and topography sets the path and final equilibrium depths of the modern mow furthermore they support the hypothesis that as a result of the high erosive power of the bottom flow and changes in bottom water speed the mow pathways and mixing rates have changed in the geological past

organo metallic complexes in an andosol a comparative study with a cambisol and podzol current soil forming processes were studied in a nonallophanic andosol from the vosges mountains north eastern france for this purpose we conducted comparative studies on the organo metallic fraction dynamics of selected profiles of an andosol and other typical soils from this region cambisol and podzol these soils are derived from old volcanic rocks under mesic soil temperature and udic soil moisture regimes the andosol profile displayed the characteristics of nonallophanic andosols large accumulation of humus active al mostly complexed with humus and low ph special attention was given to physical and microbial stability of these organo metallic associations respectively by disaggregation tests and incubation experiments the results indicated that these associations showed a strong resistance against disaggregation by water and against biodegradation moreover the very low concentration of doc al and fe in soil solutions collected by zero tension lysimeters coupled with very low amounts of water dispersed clays obtained after dispersion tests suggested that no significant translocations of these components occurred in this andosol profile low mobility together with a strong resistance against mineralization may account for the large accumulation of carbon in this andosol

monsoonal forcing of european ice sheet dynamics during the late quaternary the dynamics of northern hemisphere ice sheets during late quaternary glacials have yet been dominantly examined from a laurentide ice sheet perspective which helped shaping the idea of moisture starved glacials and small scale ice volume variability however the waxing and waning of the european ice sheet eis casts doubt on this perception understanding eis dynamics under glacial boundary conditions is crucial because its meltwater pulses influence global climate by weakening deepwater formation in the north atlantic ocean here we show that the advection of subtropical water toward the continental margin of western europe lead to enhanced moisture availability on the continent and fueled the growth of eis lobes during glacials this warm water pooling was caused by monsoonally paced enhanced mediterranean outflow water mow entrainment that dragged subtropical surface waters toward the european margin this mechanism presents a yet unrecognized marine terrestrial pathway that allows low latitude forcing to shape high latitude glaciations

magnetic and geochemical characterization of andosols developed on basalts in the massif central france identification of andosols is primarily based upon the content of their colloidal constituents clay and metal humus complexes and on the determining of andic properties this needs time and cost consuming geochemical analyses our primary aim of this study is to describe the magnetic and geochemical properties of soils rich in iron oxides derived from strongly magnetic volcanic basement in this case andosols secondary aim is to explore links between magnetic and chemical parameters of andic soils with respect to genesis factors parent material age precipitation and thickness of the soil profile six pedons of andic properties developed on basaltic lavas were analyzed down to parent rock by a set of magnetic and geochemical methods magnetic data of soil and rock samples reflect the type concentration and particle size distribution of ferrimagnetic minerals geochemical data include soil reaction ph in h2o cation exchange capacity organic carbon and different forms of extractable iron and aluminum content our results suggest the following 1 magnetic measurements of low field mass specific magnetic susceptibility can be a reliable indicator for estimating andic properties and in combination with thermomagnetic curves may be suitable for discriminating between alu andic and sil andic subtypes 2 in the studied andosols strong relationships were found between a magnetic grain size parameters precipitation and exchangeable bases b concentration of ferrimagnetic particles and degree of crystallization of free iron and c parameters reflecting changes in magneto mineralogy and soil genesis parent material age soil depth