controls on transport and fractionation of the rare earth elements in stream water of a mixed basaltic granitic catchment basin massif central france abstract we present rare earth element ree patterns of small streams from a catchment basin in the massif central france in order to characterize the individual fractionation stages for the dissolved ree from the source to the catchment outlet the upper part of the catchment is located on a basalt plateau followed downstream by deep and narrow valleys within granitic and orthogneissic bedrock basalt normalized 0 45 m filtered stream water has ree patterns slightly depleted in the light ree la sm lree on the basalt plateau close to the source followed by a continuous amplification of this lree depletion downstream at the same time also a negative ce anomaly develops in the adsorbed fraction of 0 45 m particles which has been isolated by leaching with 1 m hcl strontium and neodymium isotope ratios of stream water demonstrate that the dissolved ree are essentially of basaltic origin even in the lower granitic and gneissic part of the catchment mixing with gneiss or granite derived ree thus cannot explain the observed evolution of the ree patterns our data suggest that the ree of the 0 45 m particles in contrast to earlier studies we found no link between ree behavior and organic colloids or organic complexes this scenario is confirmed by a detailed analysis of the ree patterns at 3 stream confluences the results show that the ree do not behave conservatively during mixing at stream confluences but that the lree and ce are preferentially removed similarly to what has been observed at catchment scale our study thus underlines the importance of fe colloids for the transport and fractionation of the ree in stream water

redistribution of soil metals and organic carbon via lateral flowpaths at the catchment scale in a glaciated upland setting emerging evidence shows that interactions between soils and subsurface flow paths contribute to spatial variations in stream water chemistry in headwater catchments however few have yet attempted to quantify chemical variations in soils at catchment and hillslope scales watershed 3 ws3 at hubbard brook experimental forest new hampshire usa was studied in order to better understand pedogenesis and its relationship to subsurface water dynamics in ws3 99 soil profiles were described sampled by horizon and assigned to a hydropedologic unit hpu a functional classification previously developed using landscape and morphological metrics which corresponded with distinct water table regimes soil samples were extracted with 1 citrate dithionite d and analyzed for fed and mnd and 2 acid ammonium oxalate o and analyzed for alo feo and the rare earth elements lao ceo and pro total organic c was also measured these elements were redistributed via vertical and lateral podzolization typical horizontally layered podzols developed in the majority of the catchment due to predominantly vertical unsaturated flow however lateral flow produced four other podzol types with distinct chemistry thicker spodic horizons of laterally accumulating soils generally reflected larger pools of trace metals and subsoil organic c the spatial distribution of positive cerium anomalies ce ce in soil profiles proved to be a consistent hydropedologic indicator of lateral flow and seasonally high water table in three hillslopes despite occasional high water table in some of the hpus they were not hydric soils and were distinct from wetter podzols of coastal plains due to their high fe content this study suggests that vertical and lateral spatial variation in soil chemical composition including the complexity of ce distribution as it relates to subsurface water dynamics should be considered when studying or predicting catchment scale functions such as stream solute export and biogeochemical processes

ecohydrologic considerations for modeling of stable water isotopes in a small intermittent watershed naturally occurring stable water isotope tracers provide useful information for hydrologic model development and calibration existing models include varied approaches concerning unsaturated zone percolation mixing preferential versus matrix flow and evapotranspiration et partitioning we assess the impact of unsaturated zone simplifying assumptions when simulating the shale hills watershed shw a small 7 9 ha temperate forested watershed near petersburg pennsylvania usa with a relatively simple model we found that different model structures assumptions and parameterizations of unsaturated zone percolation had substantial impacts on the agreement between simulated and observed unsaturated zone water isotopic signatures we show that unsaturated zone percolation mixing primarily affects the unsaturated zone 18o and 2h during winter and spring and that percolation was best represented as a combination of both preferential and matrix flow we evaluate the importance and implications related to the partitioning of et into evaporation e and transpiration t and demonstrated that incorporation of a plant growth model for et partitioning substantially improved reproduction of observed hydrologic isotopic patterns of the unsaturated zone during the spring season we show that unsaturated zone percolation mixing and et partitioning approaches do not substantially influence stream 18o and 2h and conclude that observed streamflow isotopic data is not always a strong predictor of model performance with respect to intra watershed processes

rare earth element patterns a tool for identifying trace metal sources during wetland soil reduction abstract in wetland soils several soil phases such as fe iii oxyhydroxides organic matter om or mixed fe om particles can host trace metals which can be subsequently released during soil reduction anoxic and oxic wetland soil incubation experiments combined with analyses of soil solutions sampled from a natural wetland during a reduction event are used to test the possibility that rare earth elements ree could be used as a tool to identify the soil phases contributing to trace metal solubilization significant amounts of trace metals cu cr co ni and pb and ree are released during anoxic incubation of the wetland soil concomitantly with the build up of high concentrations of fe ii and dissolved organic matter dom rare earth element patterns obtained in the soil solution exhibit a middle rare earth elements mree downward concavity the ree pattern obtained from field samples yields the same feature as developed in the soil solution from an oxic incubation experiment at ph 7 designed to promote soil om desorption by contrast significantly different ree patterns are obtained in incubation experiments designed to promote chemical reduction of fe oxyhydroxides in soils the ree pattern displays a continuous ree enrichment from la to lu these distinct and recognizable ree signatures allow us to conclude that i soil organic matter is the main source of ree and trace metals during wetland soil reduction ii fe ii is provided by the reduction of amorphous fe iii nanoparticles embedded within the organic matter which do not bind ree or other trace metals in significant proportions ree and trace elements being preferentially complexed to organic matter and finally iii ree provide a reliable and powerful tool suitable for identifying trace metal sources during wetland soil reduction

podzolisation preserves ichnofossils constructed by ghost shrimp ichnofossils of ghost shrimps e g ophiomorpha nodosa and callichirus major are interpreted worldwide as records of sea level fluctuations and provide reliable evidence of sedimentation rate salinity and substrate type the preservation of these ichnofossils was previously ascribed to the polysaccharide mucus produced by ghost shrimps when burrows were built we found evidence that these ichnofossils were preserved due to the impregnation of the burrow walls by dissolved organic matter dom during podzolisation that took place after the galleries had been abandoned our study was conducted on a tropical barrier island in southeastern brazil with a spatial gradient of podzolisation intensity we made a detailed macromorphological description of the ichnofossils at the soil profile scale then we used thin sections of undisturbed soils to identify sand grain arrangements and organic matter om accumulation we detected three macromorphological structures i tubular gallery wall ii sandy infilling of the gallery and iii soil matrix outside the gallery in the micromorphology analysis we identified that the tubular wall is impregnated with monomorphic om also found outside the burrow but in lower concentration sand grains in the wall of the gallery are tightly packed causing a lower porosity than inside and outside the trace fossil the precipitation of monomorphic om is due to stagnation of dom that percolated through the soil water with dom is trapped in the wall of the tubule because of its smaller pores the ghost shrimps constructed their burrows in marine sediments without podzolisation then with the progradation of the shoreline the sediments were colonized by restinga forest adding dom to the soil and podzolisation started the extent to which dom is produced depends on vegetation development therefore the accumulation of dom in the b horizon that enables the preservation of the ichnofossils is constrained by vegetation development and progradation of the shoreline

influence of landscape position and transient water table on soil development and carbon distribution in a steep headwater catchment abstract upland headwater catchments such as those in the appalachian mountain region are typified by coarse textured soils flashy hydrologic response and low baseflow of streams suggesting well drained soils and minimal groundwater storage model formulations of soil genesis nutrient cycling critical loads and rainfall runoff response are typically based on vertical percolation development of soil horizons parallel to the land surface mineral weathering inputs limited to the rooting zone and drainage from lumped catchment reservoirs e g the subsoil as the dominant source of stream flow however detailed study of the hydrologic reference catchment at hubbard brook experimental forest nh usa shows striking spatial patterns of soil development that reflect the influence of transient water tables within the solum in nearly all landscape positions shallow bedrock and variably low hydraulic conductivity in the subsoil promote lateral flow and development of soil horizons along hillslope flowpaths rather than in vertical profiles we distinguished several morphologic units based on the presence of diagnostic horizons indicative of differing patterns of podzolization and carbon storage the distribution of soils appears to be highly dependent on local drainability and frequency and duration of transient saturation within the solum as such monitoring of hydropedologic groups and transient water table fluctuations may prove to be a sentinel for the effects of climate change on spatial distribution of soils and retention release of solutes from upland catchments

mixing of event and pre event water in a shallow entisol in sloping farmland based on isotopic and hydrometric measurements sw china

spodosol alfisol intergrades bisequal soils in ne michigan usa abstract twenty three well drained boralfs most of which exhibit bisequal soil morphology were described and sampled in ne lower michigan where they occur on landscapes shaped by greatlakean ice ca 12 ka bisequal soils in michigan are intergrades between orthods and udalfs with a spodic like upper sequum a e bs overlying a sequence of e bt c horizons thus they frequently occupy a pedogenic ecotone the purpose of the study was to characterize these soils which have been little studied and to determine if parent material homogeneity and texture are correlated with various aspects of their morphology the soils have formed in coarse loamy and fine loamy materials often with a distinct lithologic discontinuity between the two sequa the lower material interpreted as glacial till is strongly calcareous and slightly coarser textured with considerably more dolomitic gravel than the upper material water flowing through the material above may hang at the discontinuity and deposit illuvial clay bt horizons are found at or immediately below the discontinuity statistical correlations indicate that bisequal sola and their eluvial horizons are thicker when developed in coarser textured materials finer textured pedons contain more extractable fe and al in the spodic sequum but have thinner eluvial zones which have not been as completely stripped of metal cations in the finest textured pedons the e horizon may be completely lacking

hydraulic properties of a low permeable rupture zone on the yingxiu beichuan fault activated during the wenchuan earthquake china implications for fluid conduction fault sealing and dynamic weakening mechanisms abstract fluid transport properties of fault rocks are crucial parameters that affect earthquake nucleation and rupture propagation in this study we examined the internal structure mineral composition and fluid transport properties of fault rocks collected from two shallow boreholes penetrating a granitic rupture zone on the yingxiu beichuan fault ybf that was activated during the 2008 wenchuan earthquake fluid transport properties were measured using water as pore fluid at effective pressures p e ranging from 10 mpa to 165 mpa permeabilities of fault rocks exhibit a wide variation from 2 1 10 22 m 2 to 4 6 10 17 m 2 strongly depending on rock types and overburden pressure specifically at p e of 165 mpa the damage zone samples have permeabilities from 5 0 10 21 m 2 to 1 2 10 17 m 2 and the fault gouges are between 2 1 10 22 m 2 and 3 1 10 19 m 2 thus the ybf consists of a low permeability fault core acting as fluid barrier and surrounding high permeability damage zones acting as fluid conduits combining the structural and compositional results and transport data together we propose that the interplay between cataclasis and fluid rock interactions controls the hydraulic properties and their response to the fault zone evolution it is noteworthy that we measured extremely low permeabilities but high porosities and high specific storages for the gouges the cemented cataclasites which are inferred to be equivalent to the rocks in which the wenchuan earthquake nucleated also have low permeabilities suggesting the fault zone is a potential area for fluid storage and capable of generating high pore pressure at depths according to our laboratory data we found fluid pressurization could occur at depths below 2 7 km we suggest thermal pressurization has played an important role in causing the dynamic weakening of the wenchuan earthquake

impacts of old comparatively stable treethrow microtopography on soils and forest dynamics in the northern hardwoods of michigan usa abstract uprooting represents a key disturbance process in forests forming pit mound microtopography which can then dramatically impact pedogenesis and the forest ecology at our study sites in northern michigan where well drained sandy spodosols dominate pit mound microtopography tends to persist for millennia because of its persistence the influence of this type of microtopography is greater here than in most forests in that respect our sites represent an end member along a continuum of forest soil disturbance by uprooting we studied post uprooting pedogenesis at 14 dated pit mound pairs mapped and characterized the pit mound topography over 2 8 ha the soils below within 317 soil profiles and the trees above to better understand the complex interactions among this type of disturbance regime and forest dynamics we used a pair correlation function and chi square test approach to study the relationships between treethrow features and the living trees at one of these sites soil variability as affected by microtopography was studied using geostatistics pit mound microtopography here covers 17 of the surface and are generally randomly distributed across the forest floor mounds are more prominent features of the forest floor than are pits pits infill with sediment and litter obscuring them whereas mounds persist for millennia in the sandy sediment because runoff is limited and litter forms a protective armor treethrow features had volumes of roughly 214 225 m3 ha and on average each uprooting event translocated 0 6 m3 of soil about 0 8 m laterally and 0 1 0 2 m vertically areas of the pit mound features did not differ between slope aspects supporting an idea that on the gentle slopes of the study sites uprooting does little to affect the movement of sediment downslope the exceptional longevity of the treethrow features is probably a factor in the statistical randomness with which treethrow features are distributed on the forest floor as footprints of many uprooting events are interlaced across the forest floor as reported elsewhere soil development was accelerated in pits leading to increasingly greater differences in soil development between pits and mounds over time and illustrating the concept of locally divergent pedogenesis in older pits the abnormally thick soil profiles extent so far below the depth of rooting that they are unlikely to be disturbed by future uprooting events on the coarser spatial scale of the forest stand uprooting decreased the ranges and increased the sills of spatial autocorrelation for o e and bhs horizon thicknesses the effect of treethrow dynamics on soil characteristics was greatest and statistically most significant for e horizon thicknesses where the range was decreased from 13 m to 10 m whereas the maximal level of semivariance sill increased by 42 all tree species preferred treethrow mounds to pits or undisturbed microsite for regeneration especially acer saccharum

pedogenic processes and clay transformations in bisequal soils of the southern taiga zone in bisequal soils a complex combination of pedogenic processes has occurred and the minerals that arise from a specific soil forming process may have been modified by other processes in this work we investigated the mineralogical composition of the clay fraction and related it to pedogenic processes in three soils of the russian taiga the soils showed evidences of clay translocation podzolisation and gleying with different intensities and combinations clay translocation was present in all profiles but better expressed in profile 2 evidences of podzolisation were found in profiles 2 and 3 but in this latter hydromorphic processes have also occurred in profile 1 almost permanent water stagnation has lead to the development of a thick sphagnum cover in all profiles during the formation of the alfisol sequa the transformation of illite into vermiculite or smectite has occurred through the formation of mixed layered minerals while the ph favoured al intercalation in the interlayer when podzolisation started the presence of hiv his in the e horizon was no longer favoured because of al complexation by organic acids but in the bs horizons al intercalation in the interlayers continued thus prolonging a mineralogical process that has started during the previous pedogenic phase the formation of swelling minerals was moderate and related to the cheluviation phase of podzolisation we found swelling mixed layer minerals only in the surface horizons of profile 1 and 3 where the vegetation cover was favourable to the production of aggressive organic acids and thus al may be removed also from the structural sites of phyllosilicates the reducing conditions acted upon soil minerals but affected directly only fe oxi hydr oxides the dissolution of the protective fe films from mineral surfaces has however favoured the physical disintegration of feldspar grains where the waterlogging conditions were almost permanent

behaviour of rare earth elements and yttrium in ferromanganese concretions gibbsite spots and the surrounding terra rossa over dolomite during chemical weathering abstract the behaviour of rare earth elements rees and yttrium y during chemical weathering processes has been investigated on a 4 05 m thick terra rossa profile over dolomite on the yunnan guizhou plateau china in this profile ferromanganese concretions and gibbsite spots coexist in the terra rossa solum analyses of rees y zr f s and toc as well as mineralogical studies were conducted on a suite of ferromanganese concretions gibbsite spots terra rossas dolomites and insoluble residues from the underlying dolomite these analyses helped us to understand the mobilization redistribution and fractionation of rees and y during chemical weathering the rees and y are mobilized and redistributed during the terra rossa formation rees except for ce are removed from the upper and middle profiles transferred downwards and then precipitated in the base profile resulting in remarkable enrichment in the terra rossa near the weathering front the significant increase of ph near the weathering front was responsible for ree excluding ce and y enrichment in the base profile y is quite mobile during extreme chemical weathering and most of it was carried away from the profile because of very efficient oxidative fractionation of ce a significant positive ce anomaly in terra rossa was found in the middle of the profile whereas the terra rossa near the weathering front exhibited notably negative ce anomalies moreover the presence of cerianite and its content in the ferromanganese concretions can explain the markedly positive ce anomaly and the variation of ce ce values with depth in profile these ce anomalies are characteristic of the geochemical environment especially the redox condition studies of ree distribution in the ferromanganese concretions gibbsite spots and surrounding terra rossa revealed that significant ree fractionation occurred rees and y were preferentially concentrated in the ferromanganese concretions rather than in the gibbsite spots the water rock interaction resulted in m type tetrad effects in some of the ferromanganese concretions gibbsite spots and terra rossa samples in addition the tetrad effect in terrestrial weathering processes likely played an important role in the fractionation of rees and y such as y ho sm nd and the eu anomaly change

diel behavior of rare earth elements in a mountain stream with acidic to neutral ph abstract diel 24 h changes in concentrations of rare earth elements ree were investigated in fisher creek a mountain stream in montana that receives acid mine drainage in its headwaters three simultaneous 24 h samplings were conducted at an upstream station ph 3 3 an intermediate station ph 5 5 and a downstream station ph 6 8 the ree were found to behave conservatively at the two upstream stations at the downstream station ree partitioned into suspended particles to a degree that varied with the time of day and concentrations of dissolved ree were 2 9 to 9 4 fold 190 to 830 higher in the early morning vs the late afternoon the decrease in dissolved ree concentrations during the day coincided with a corresponding increase in the concentration of ree in suspended particles such that diel changes in the total ree concentrations were relatively minor 27 to 55 increase at night across the lanthanide series the heavy ree partitioned into the suspended solid phase to a greater extent than the light ree filtered samples from the downstream station showed a decrease in shale normalized ree concentration across the lanthanide series with positive anomalies at la and gd and a negative eu anomaly as the temperature of the creek increased in the afternoon the slope of the ree profile steepened and the magnitude of the anomalies increased the above observations are explained by cyclic adsorption of ree onto suspended particles of hydrous ferric and aluminum oxides hfo hao conditional partition coefficients for each ree between the suspended solids and the aqueous phase reached a maximum at 1700 hours and a minimum at 0700 hours this pattern is attributed to diel variations in stream temperature possibly reinforced by kinetic factors i e slower rates of reaction at night than during the day estimates of the enthalpy of adsorption of each ree onto suspended particles based on the field results averaged 82 kj mol and are similar in magnitude to estimates in the literature for adsorption of divalent metal cations onto clays and hydrous metal oxides the results of this study have important implications to the use of ree as hydrogeochemical tracers in streams

pyrite and other sulphur minerals in giant aquic spodosols western australia abstract thirty very deep aquic spodosols in swales of the bassendean dune system western australia were investigated for their potential to acidify due to their contents of acid forming sulphur minerals pyrite commonly occurs in b bh c and sometimes a and e horizons of these soils two morphologies of pyrite are present single crystals of pyrite are euhedral cubic or octahedral 1 m and framboidal pyrite aggregate grains range from 1 to 10 m elemental sulphur in the form of anhedral particles 10 500 nm may occur in e b and bh horizons and is strongly associated with organic matter and jarosite sometimes occurred in the a horizon rare marcasite and mackinawite are other acid generating sulphide minerals and indicate the diverse redox and other chemical conditions that exist in these spodosols consequently drying and aeration of these soils due to drainage and possibly also to climate change acidifies both soil and groundwater these spodosols are therefore acid sulphate soils acid buffering is mostly minor and is provided by organic matter and allophane these observations of acid generating sulphides in spodosols may indicate that very acid nonaquic spodosols elsewhere were once saturated and contained pyrite before the profiles experienced permanent or episodic oxidising conditions

rare earth elements as geochemical tracers of regional groundwater mixing abstract the rare earth elements ree were analyzed in a groundwater system from south central nevada i e ash meadows national wildlife refuge the spring mountains pahranagat national wildlife refuge and the nevada test site in order to investigate their potential use as tracers of regional groundwater flow previous investigations using conservative tracers e g deuterium and uranium isotopes identified recharge in local mountains as the primary source 60 70 of total discharge for the springs in the regional discharge zone i e ash meadows with the remaining contribution being interbasin flow from the northeast initial mixing calculations for these groundwaters using shale normalized ree patterns agreed well with the previous studies however because the rees are not expected to behave conservatively in natural waters the effect of both solution complexation which acts to enhance the stability of the rees in solution as well as surface complexation responsible for the particle reactive behavior of the rees were examined in subsequent mixing calculations in order to assess the roles of solution and surface complexation relative partitioning coefficients were estimated for each ree in each groundwater by evaluating the ratio of the ionic strength corrected co 3 1 ree co 3 2 ree and co 3 2 f to the first hydrolysis binding constants for the rees the relative partitioning coefficients were then used to calculate ree patterns expected to develop and persist in solution as a consequence of solution and surface complexation the calculated ree values closely resembled the actual measured ree concentrations suggesting that the rees are in fact controlled by solution and surface complexation in these groundwaters the calculated ree concentrations were subsequently used to determine mixing ratios the results of which coincided with the initial calculations as well as the previous studies the results of this study suggest that solution complexation of the rees is sufficient to overcome to a certain degree the affinity of the rees to be adsorbed onto surface sites in the aquifers such that distinctive ree signatures develop and persist in solution in groundwaters from different aquifers the ability of solution complexation to overcome surface complexation is likely related to the formation of the negatively charged dicarbonato complex i e ln co 3 2 where ln is any ree which accounts for significant fractions of each ree in these groundwaters

permeability and storativity of binary mixtures of high and low permeability materials 1 as a first step toward determining the mixing laws for the transport properties of rocks we prepared binary mixtures of high and low permeability materials by isostatically hot pressing mixtures of fine powders of calcite and quartz the resulting rocks were marbles containing varying concentrations of dispersed quartz grains pores were present throughout the rock but the largest ones were preferentially associated with the quartz particles leading us to characterize the material as being composed of two phases one with high permeability and the second with low permeability we measured the permeability and storativity of these materials using the oscillating flow technique while systematically varying the effective pressure and the period and amplitude of the input fluid oscillation control measurements performed using the steady state flow and pulse decay techniques agreed well with the oscillating flow tests the hydraulic properties of the marbles were highly sensitive to the volume fraction of the high permeability phase directly related to the quartz content below a critical quartz content slightly less than 20 wt the high permeability volume elements were disconnected and the overall permeability was low above the critical quartz content the high permeability volume elements formed throughgoing paths and permeability increased sharply we numerically simulated fluid flow through binary materials and found that permeability approximately obeys a percolation based mixing law consistent with the measured permeability of the calcite quartz aggregates

travel times in the vadose zone variability in space and time water travel times reflect hydrological processes yet we know little about how travel times in the unsaturated zone vary with time using the soil physical model hydrus 1d we derived time variable travel time distributions for 35 study sites within the attert catchment in luxembourg while all sites experience similar climatic forcing they differ with regard to soil types 16 cambisols 12 arenosols and 7 stagnosols and the vegetation cover 29 forest and 6 grassland we estimated site specific water flow and transport parameters by fitting the model simulations to observed soil moisture time series and depth profiles of pore water stable isotopes with the calibrated model we tracked the water parcels introduced with each rainfall event over a period of several years our results show that the median travel time of water from the soil surface to depths down to 200 cm is mainly driven by the subsequent rainfall amounts the median time until precipitation is taken up by roots is governed by the seasonality of evapotranspiration rates the ratio between the amount of water that leaves the soil profile by on the one hand and evaporation and transpiration on the other hand also shows an annual cycle this time variable response due to climatic forcing is furthermore visible in the multimodal nature of the site specific master transit time distribution representing the flow averaged probability density for rainwater to become recharge the spatial variability of travel times is mainly driven by soil texture and structure with significant longer travel times for the clayey stagnosols than for the loamy to sandy cambisols and arenosols

micrometer silicon isotope diagnostics of soils by uv femtosecond laser ablation this study presents the first si isotope data of the principle si pools in soils determined by a uv femtosecond laser ablation system coupled to a multicollector inductively coupled plasma mass spectrometer mc icp ms this method reveals accurate and precise si isotope data on bulk materials and at high spatial resolution on the mineral scale the following si pools have been investigated a the si source to soils on all major silicate minerals on thin sections from bedrock fragments in the soil profiles b bulk soils particle size 2 mm after fusion to glass beads with an iridium strip heater or pressed into powder pellets c separated clay fractions as pressed powder pellets and e separated phytoliths as pressed powder pellets multiple analyses of three rock standards bhvo 2 agv 1 and rgm 1 as fused glass beads and as pressed powder pellets reveal 30si values within the expected range of igneous rocks the mpi ding reference glass kl2 g exhibits the same si isotope composition after remelting by an iridium strip heater showing that this technique does not alter the isotope composition of the glass we used this approach to investigated two immature cambisols developed on sandstone and paragneiss in the black forest germany respectively bulk soils show a largely uniform si isotope signature for different horizons and locations which is close to those of primary quartz and feldspar with 30si values around 0 4 soil clay formation is associated with limited si mobility which preserves initial si isotope signatures of parental minerals an exception is the organic horizon of the paragneiss catchment where intense weathering leads to a high mobility of si and significant negative isotope signatures as low as to 1 00 in bulk soils biogenic opal in the form of phytoliths exhibits negative si isotope signatures of about 0 4 these results demonstrate that uv femtosecond laser ablation mc icp ms provides a tool to characterize the si isotope signature of the principle si pools left behind after weathering and si transport have altered soils these results can now serve as a fingerprint of the residual solids that can be used to explain the isotope composition of dissolved si in soil solutions and river water which is mostly enriched in the heavy isotopes

direct observation of tetravalent cerium in ferromanganese nodules and crusts by x ray absorption near edge structure xanes abstract x ray absorption near edge structure xanes was successfully applied for the direct determination of ce valence in hydrogenetic ferromanganese nodules two samples and crust one sample rare earth element ree patterns of the hydrogenetic ferromanganese nodules and crust recovered from the pacific ocean show large positive ce anomalies especially when normalized to seawater despite some disadvantages in the spectroscopic analysis of ce in natural samples e g low concentration and interference from other elements intense synchrotron radiation and measurement of fluorescent xanes with semiconductor detectors having high energy resolution enabled us to detect xanes at ce l iii edge in the ferromanganese nodule or crust in the xanes spectra of the nodule or crust large double peaks were observed showing that the oxidation state of ce in the nodule or crust is predominantly tetravalent with little contribution from ce iii this is the first in situ quantitative analysis of ce iv among total ce in natural samples as a trace element as far as we know the results obtained by xanes seem to be consistent with the percentage of ce iv estimated from seawater normalized ree patterns suggesting that seawater is a precursor of ree in the marine deposits the present results also confirm that ce enrichment relative to other rees in hydrogenetic ferromanganese deposits is due to oxidative removal of ce from seawater to the ferromanganese nodules and crust in the marine environment comparison of xanes spectra of ce sorbed on synthetic manganese oxide and ceo 2 vs those of the ferromanganese nodules and crust suggests that the initial reaction of ce with the ferromanganese nodules and crust is the sorption of dissolved ce iii to the manganese oxide surface

rare earth element concentrations and speciation in organic rich blackwaters of the great dismal swamp virginia usa concentrations of rare earth elements ree major inorganic solutes and dissolved organic carbon doc were measured in waters from the great dismal swamp in southeastern virginia including lake drummond ph 4 3 and its principal surface inflows and outflow concentrations of ree are high in the lake average nd 8 nmol kg and the acidic doc rich inflow and out flow waters i e nd 12 5 nmol kg in jericho washington ditch and 8 nmol kg in feeder ditch respectively the slightly acidic ph 6 6 4 inflow waters from west of the suffolk scarp that comprise the chief source of surface water flow into lake drummond exhibit lower ree concentrations nd 3 4 7 nmol kg great dismal swamp waters are all enriched in the middle rees compared to the light and heavy rees lree and hree when normalized to upper continental crustal ucc values rare earths are positively correlated to doc concentrations in great dismal swamp waters and inversely correlated with ph speciation calculations using a modified version of the well established humic ion binding model v predict that organic matter complexes are the predominant form of dissolved rees in great dismal swamp waters despite significant competition from aqueous fe and al for organic matter binding sites adsorptive cathodic stripping voltammetry acsv was employed using a previously developed competitive ligand equilibration approach that involved adding the o cresolphthalexon ocp ligand to directly investigate ree complexation with natural organic ligands in great dismal swamp waters although preliminary the results of the acs voltammetric titrations are consistent with dominance of organic matter complexes of rees in great dismal swamp waters the results of the speciation modeling and the voltammetric titrations all point towards control of dissolved rees in great dismal swamp waters by complexation of these heavy metals with natural organic matter

the geochemistry of rare earth elements in groundwater from the carnmenellis area southwest england shallow groundwater samples from the carnmenellis area of southwest england collected from wells boreholes springs adits and stream baseflow represent recently recharged waters of low salinity their major ion concentrations closely reflect the lithology of their host rocks which comprise the carnmenellis granite and devonian metasediments and metabasite of greenschist grade groundwaters from the granite are predominantly na cl or na ca cl type whilst those from the metasediment are na ca mg cl hco3 waters with a larger range of compositions the major ion compositions are predominantly a function of water rock interaction processes and the larger range of metasediment water compositions probably reflects the greater lithological variation the ph of groundwater samples circulating through granite is typically lower than that of groundwater in the metasediments the range being 4 3 to 7 2 median 5 7 and 4 7 to 8 0 median 6 6 respectively rare earth element ree concentrations of 0 45 m filtered groundwater samples have been determined by inductively coupled plasma mass spectrometry icp ms a large range of concentrations exists and many are below detection limits but levels reach up to 229 g 1 1 6 m total rees the rees are strongly controlled by ph with higher levels in groundwaters of ph 6 chondrite normalised profiles are light rare earth element lree enriched compared to heavy rare earths hrees with a common slight negative eu anomaly both features reflecting the compositions of their host rocks ree profiles therefore appear to be controlled by water rock interactions involving predominantly ree enriched minerals in the granite the rees are probably derived mainly from the accessory minerals monazite and apatite as well as the high ree framework minerals biotite and muscovite the source of rees in groundwater from the metasediments is more uncertain but probably includes clay minerals chlorite and carbonate ree compositions normalised to shale have flatter profiles although many are slightly convex with higher normalised sm eu and gd values a few metasediment derived waters with high total ree concentrations have lree enriched shale normalised patterns it is suggested that the bulk of the rees in these few samples is colloidal rather than totally dissolved groundwaters from the metasediments have a notable depletion in ce which is distinct from waters in the granite this depletion is problematic in that it is difficult to see how redox processes could be the dominant control since groundwaters from the metasediments are unlikely to be more oxidising than those from the granite likewise variations in ph fail to totally explain the distinctions in ce concentration and la ce ratios between the two water types it is therefore suggested that the ce contents are largely source related rather than process related the observed ree compositions of granite and metasedimentderived groundwaters from the carnmenellis area are so distinctive that the rees in general and ce in particular might be useful as future tracers in studies of water rock interaction and groundwater provenance

a discrete particle representation of hillslope hydrology hypothesis testing in reproducing a tracer experiment at gardsjon sweden despite the long history of the continuum equation approach in hydrology it is not a necessary approach to the formulation of a physically based representation of hillslope hydrology the multiple

converse pathways of soil evolution caused by tree uprooting a synthesis from three regions with varying soil formation processes abstract post disturbance pedogenetic pathways were characterized in three landscapes representing different degrees of weathering and leaching tree uprooting has been the main form of disturbance in all three landscapes we hypothesized that the pedogenetic effect of trees due to uprooting is mainly governed by the regional degree of pedogenesis which in turn affects soil and landscape evolution the three regions were characterized by a chronosequence of treethrow pit mound pairs from fresh to almost leveled forms two sequences originated from the czech republic one on haplic cambisols and one on entic podzols the third and the oldest chronosequence in michigan usa was on albic podzols dating back to 4080 bce we analyzed 38 chemical and physical soil properties for 700 samples from 42 pit mound pairs in these regions ordination and regression techniques allowed us to evaluate the effect of sample depth microsite pit mound and undisturbed control position and age of the soils formed after uprooting depth was the most significant variable in all regions p

scale interactions involved in the initiation structure and evolution of the 15 december 1992 mcs observed during toga coare part ii mesoscale and convective scale processes abstract this paper the second of a series documents the precipitation and kinematic and thermodynamic structure of a tropical mesoscale convective system observed by instrumented aircraft on 15 december 1992 during toga coare radar derived precipitation fields indicate that the studied system consists of two subsystems s1 and s2 characterized by distinct internal dynamics and morphological structures the retrieved kinematic and thermodynamic structures are compared in detail with the synoptic scale characteristics described in part i of this paper so as to evaluate the scale interactions involved in the internal organization of this convective system it is shown essentially that the synoptic scale circulation governs the mesoscale and convective scale motions and therefore determines the internal organization of the selected system in particular this study highlights the major role played by the synoptic scale vertical wind shear in the internal structure of this tropical mesoscale system m

temporal variations in the fractionation of the rare earth elements in a boreal river the role of colloidal particles rare earth element ree data from weekly sampling of the filtered 0 45 m and suspended particulate phase during 18 months in the kalix river northern sweden are presented together with data on colloidal particles and the solution fraction 3 kda the filtered ree concentration show large seasonal and temporal variations in the river lanthanum varied between approximately 300 and 2100 pm high ree concentration in the filter passing fraction is related to increased water discharge and there is a strong correlation between the ree concentration organic carbon al and fe physical erosion of detrital particles plays a minor role for the yearly transport of particulate ree in this boreal river system the suspended particulate fraction which is dominated by non detrital fractions accounted for only 35 of the yearly total transport of la in the river approximately 10 of the ree were transported in detrital particles during winter at spring flood in may about 30 of the lree and up to 60 of the hree where hosted in detrital particles ultrafiltration of river water during spring flood shows that colloidal particles dominate the transport of filter passing ree less than 5 of the filtered ree are found in the fraction smaller than 3 kda the colloidal fraction shows a flat to slightly lree enriched pattern whereas the solution fraction 3 kda show an hree enriched pattern compared with till in the catchment suspended particles show a lree enriched pattern data indicate that the ree are associated with two phases in the colloidal and particulate fraction an organic rich phase with associated al fe and an fe rich fe oxyhydroxide inorganic phase the ce anomaly in the suspended particulate fraction in the river shows systematic variations and can be used to interpret fractionation processes of the ree during weathering and transport there was no anomaly at maximum spring flood but during the ice covered period the anomaly became more and more negative the temporal and seasonal variations of the ce anomaly in the suspended particulate phase reflect transport of ree c al fe enriched colloids from the upper section of the till and or from mires to the river at storm events

numerical estimation of effective permeability in sand shale formations a numerical approach is used to estimate effective permeability in sand shale formations under steady state uniform flow conditions permeability is modeled as a binary second order stationary random function taking on two possible values kss and ksh in sandstone and shale respectively this model is realistic since experience with sandstone reservoirs has shown that randomly dispersed low permeability shales are the single dominant heterogeneity affecting flow behavior the cases of both spatially correlated and uncorrelated permeabilities are considered for the case of spatially correlated permeability an autocovariance model was fitted to data from the assakao fluvial sandstone which outcrops in the tassili region of the central sahara the turning bands method was used to simulate the spatially correlated permeabilities of blocks discretizing the flow field effective permeability was found to depend on the shale volume fraction the spatial covariance structure and the dimensionality of the flow system existing analytical methods for estimating effective permeability in a two phase medium are found to be inaccurate when compared to numerical results or unapplicable to stratified environments in addition to providing a check of analytical work the numerical approach is found to be a useful tool for exploring the effects of reservoir heterogeneity on flow behavior in a qualitative sense

binding and transport of rare earth elements by organic and iron rich nanocolloids in alaskan rivers as revealed by field flow fractionation and icp ms abstract water samples were collected from six small rivers in the yukon river basin in central alaska to examine the role of nanocolloids 0 5 40 nm in the dynamics and transport of rare earth elements rees in northern high latitude watersheds influenced by permafrost total dissolved 40 nm colloids in a river sampled at higher altitude the

mineralogical control of rare earth elements in acid sulfate soils abstract major trace and rare earth element concentrations were measured in porewater surface water and sediments at an acid sulfate soil site the concentrations of la and ce in porewater are up to 1 3 ppm there is a strong correlation between ree concentration and acidity except that the maximum concentrations were consistently found below the horizon of maximum acidity associated with an increase in ph to ca 4 and change in mineralogy from jarosite dominated to goethite dominated mottles jarosite replacement by goethite is as expected with the rise in ph which in turn is due to the occurrence of a fossil shell bed just below the rare earth element patterns in the porewaters are enriched in the mree with respect to post archaean australian shale paas measurements and calculations show that this is in accord with experiments on low degree partial dissolution of jarosite even when the jarosite itself is highly enriched in lree there is a clear fractionation in the patterns between the clay rich soil matrix which is slightly depleted in the lree when normalized to paas la ybpaas 0 5 and the secondary mineral phase jarosite which is enriched in the lree la ybpaas 15 50 the ree pattern in the porewater changes with the transition from jarosite to goethite rich mottles becoming relatively more enriched in the lree compared to the hree which is consistent with the incongruent dissolution of jarosite to form goethite and the release of greater amounts of jarosite ree to solution including proportionately more of the jarosite compatible lree maximum surface water ree concentrations in acidic water were 100 200 ppb la and ce ree patterns in surface water were very similar to the porewater transition zone enriched in the mree but asymmetric relatively enriched in the lree compared to the hree

geochemical differences in an oxisol spodosol toposequence of amazonia brazil the morphology and geochemical characteristics of the soils of a toposequence near manaus brazil have been determined such toposequences occur on slopes leading down into valleys cut in a nearly level plateau oxisols form the upper and spodosols the lower members of toposequences the transition from the oxisols down the slope through a band of ultisols to the spodosols is very gradual lowest members of the toposequences spodosols do not occupy the valley floors great contrasts as well as shared characteristics occur among members of the toposequence chosen for study proportions of clay in the oxisols are 80 90 as contrasted to 2 5 in the spodosols changes in amounts of clay are gradual continuing down the slope the clay fraction is kaolinitic all soils are strongly acid and have very low base saturation the characteristics of the soils imply that several processes of weathering and pedogenesis have been operative the small amount of sio2 in the oxisols is attributed to dissolution of quartz without corresponding hydrolysis of kaolinite the decreases in clay contents and increases in quartz in the soils from the upper to the lower end of the toposequence are attributed to a combination of hydrolytic weathering and either or both of clay eluviation and selective erosion of that fraction the sequence of soils within the toposequences further suggests that a podzolization process begins when a critical stage in impoverishment is reached destruction of clay minerals continues but the migration of organo mineral complexes within profiles becomes important a part of those complexes moves out of the spodosols to form black waters in the streams

modern and ancient pedogenesis as revealed by holocene fire northern apennines italy abstract soil needs a long time for its development and traces of the past effects of climate vegetation cover and human activity can persist through time thus paleosols are widely studied for paleo environmental reconstructions so to understand the effects of climate changes and or human activities that for millennia transformed the land and interacted with soil formation the aim of this work was to assess the influence of both ancient and modern environmental conditions on the pedogenesis at mt cimone northern apennines italy in particular we compared buried paleosols and the overlying modern soils separated by a charcoal enriched horizon aub along an altitudinal climatic sequence from 1553 to 1939 m above sea level the radiocarbon age of the aub horizon was 3040 2940 calibrated years before present therefore it was taken as a chronological marker for the beginning of soil formation of the modern soil unit the horizons thickness of the modern soil varied among the sites suggesting the occurrence of accumulation erosion processes with a differential redistribution over the aub horizon of the soil material transported by surface water runoff the soil horizon sequence in the paleosol at lower altitudes 1553 1700 m was rather simple bw c horizons indicating the occurrence of a moderately intense paleo pedogenesis instead from 1700 to 1900 m mostly above the actual tree line the paleosol showed well expressed processes of eluviation illuviation of organic matter and fe al oxyhydroxides which led to the formation of e bs or bhs c horizons sequences podzols these findings agree with previous studies dealing with climatic and palynological changes occurred in this area in the last seven millennia at altitudes 1700 m the ancient pedogenetic phase occurred during the atlantic climatic period with a cryic soil temperature regime no permafrost presence of seasonal snow and a progressive tree species transition from abies alba to oaks of warm temperate climate the modern pedogenetic phase seemed to be affected by local wetter conditions and human induced forest disturbance as it is testified by the change in the pollen abundance

rare earth elements in japan sea sediments and diagenetic behavior of ce ce results from odp leg 127 the relative effects of paleoceanographic and paleogeographic variations sediment lithology and diagenetic processes on the recorded rare earth element ree chemistry of japan sea sediments are evaluated by investigating ree total abundances and relative fractionations in 59 samples from ocean drilling program leg 127 ree total abundances ree in the japan sea are strongly dependent upon the paleoceanographic position of a given site with respect to terrigenous and biogenic sources ree concentrations at site 794 yamato basin overall correspond well to aluminosilicate chemical indices and are strongly diluted by sio2 within the late miocene pliocene diatomaceous sequence eueu values at site 794 reach a maximum through the diatomaceous interval as well most likely suggesting an association of eueu with the siliceous component or reflecting slight incorporation of a detrital feldspar phase ree at site 795 japan basin also is affiliated strongly with aluminosilicate phases yet is diluted only slightly by siliceous input at site 797 yamato basin ree is not as clearly associated with the aluminosilicate fraction is correlated moderately to siliceous input and may be sporadically influenced by detrital heavy minerals originating from the nearby rifted continental fragment composing the yamato rise the biogenic influence is largest at site 794 moderately developed at site 797 and of only minor importance at site 795 reflecting basinal contrasts in productivity such that the yamato basin records greater biogenic input than the japan basin while the most productive waters overlie the easternmost sequence of site 794 cece profiles at all three sites increase monotonically with depth and record progressive diagenetic lree fractionation the observed cece record does not respond to changes in oxygenation state of the overlying water and cece correlates slightly better with depth than with age the downhole increase in cece at site 794 and site 797 is a passive response to diagenetic transfer of lree except ce from sediment to interstitial water at site 795 the overall lack of correlation between cece and lanybn suggests that other processes are occurring which mask the diagenetic behavior of all lrees first order calculations of the ce budget in japan sea waters and sediment indicate that 20 of the excess ce adsorbed by settling particles is recycled within the water column and that an additional 38 is recycled at or near the seafloor data from masuzawa and koyama 1989 thus because the remaining excess ce is only 10 of the total ce there is not a large source of ce to the deeply buried sediment further suggesting that the downhole increase in cece is a passive response to diagenetic behavior of the other lrees the ree chemistry of japan sea sediment therefore predicts successive downhole addition of lrees to deeply buried interstitial waters

cerium anomalies in lateritic profiles the ree geochemistry and mineralogy have been studied in four lateritic profiles one derived from a syenite akongo sw cameroon the others being developed on a gneissic basement and located along a soil toposequence goyoum e cameroon there is a fractionation between lree and hree in the lateritic samples during weathering the weathered residual products being enriched in lree from la to eu and depleted in hree from gd to lu sampled waters are enriched in hree in relation to the syenite host rock a positive ce anomaly has been found systematically at the top of the saprolite beneath a zone of iron oxide accumulation in the laterite up to 2000 ppm ce may be present in the akongo profile cerianite ceo2 is present as very fine coatings in non ferruginous clayey domains primary ree bearing accessory minerals are weathered at the bottom of the profile specifically allanite and apatite are transformed into florencite and rhabdophane but these phases have no ce anomaly all the data are interpreted as the result of the following processes 1 1 ree leaching in a reducing environment 2 2 oxidation of ce3 to ce4 in an oxidizing environment 3 3 deposition of cerium as cerianite whereas the other ree remain in solution

upper soil horizons control the rare earth element patterns in shallow groundwater several studies dedicated to the aquatic geochemistry of rare earth elements rees have displayed a wide topography related spatial variability in the ree signatures of shallow groundwater the aim of this study was to understand the processes leading to this specific ree signature notably with regard to the size of the ce anomaly soils were sampled in order to encompass the expected topographic variability in the organic carbon oc fe mn ratio leaching experiments were performed with the uppermost horizons of the soil the ree patterns that developed in the soil leaching solution were similar to the ree patterns for the shallow groundwater collected in this catchment the negative ce anomaly evolves in a similar manner according to the topography this spatial variation is strongly correlated with the soil oc fe ratio for a low oc fe ratio the negative ce anomaly amplitude in the soil solution is large whereas a high oc fe ratio generates a small or insignificant ce anomaly reductive dissolution experiments using soil with low oc fe ratios demonstrated that the ree pattern for soil fe oxyhydroxides exhibited a positive ce anomaly and hree enrichment indicating a preferential association of these elements with fe oxyhydroxides the rare earth element signature observed in the shallow groundwater is affected by fe oxyhydroxides present in the upper soil horizons in contrast in soil with a high oc fe ratio the ree pattern obtained under reducing conditions did not exhibit any ce anomaly suggesting that in the bottomland the ree signature is affected by the oc content in the uppermost soil this study highlights the impact of organic matter on the fe pedofeatures which control the development of a negative ce anomaly in shallow groundwater

a preliminary assessment of water partitioning and ecohydrological coupling in northern headwaters using stable isotopes and conceptual runoff models we combined a conceptual rainfall runoff model and input output relationships of stable isotopes to understand ecohydrological influences on hydrological partitioning in snow influenced northern catchments six sites in sweden krycklan canada wolf creek baker creek dorset scotland girnock and the usa dry creek span moisture and energy gradients found at high latitudes a meta analysis was carried out using the hydrologiska byrans vattenbalansavdelning hbv model to estimate the main storage changes characterizing annual water balances annual snowpack storage importance was ranked as wolf creek krycklan dorset baker creek dry creek girnock the subsequent rate and longevity of melt were reflected in calibrated parameters that determine partitioning of waters between more rapid and slower flowpaths and associated variations in soil and groundwater storage variability of stream water isotopic composition depends on the following i rate and duration of spring snowmelt ii significance of summer autumn rainfall and iii relative importance of near surface and deeper flowpaths in routing water to the stream flowpath partitioning also regulates influences of summer evaporation on drainage waters deviations of isotope data from the global meteoric water line showed subtle effects of internal catchment processes on isotopic fractionation most likely through evaporation such effects are highly variable among sites and with seasonal differences at some sites after accounting for climate evaporative fractionation is strongest at sites where lakes and near surface runoff processes in wet riparian soils can mobilize isotopically enriched water during summer and autumn given close soil vegetation coupling this may result in spatial variability in soil water isotope pools available for plant uptake we argue that stable isotope studies are crucial in addressing the many open questions on hydrological functioning of northern environments 2015 the authors hydrological processes published by john wiley sons ltd

zircon typology combined with smnd whole rock isotope analysis to study brioverian sediments from the armorican massif the identification of source materials contributing to mature terrigenous clastic deposits is made difficult due to a lack of useful discriminant criteria sm nd isotope analysis can provide some indication of the present of mantle derived constituents in clastic rocks however since this method is based on whole rock samples it is only possible to obtain the averaged composition of the different source materials involved moreover sm nd isotope systematics can be strongly influenced by the presence of heavy minerals rich in rare earth elements and or displaying isotopic ratios very different to the sedimentary host in this manner 0 1 of zircon or 0 01 of monazite from an extraneous source is sufficient to modify significatively the sm nd signature of the whole rock the typological study of zircon populations is an extremely valuable tool especially since this mineral is highly resistant and exhibits a morphology controlled by the physical and chemical conditions under which it crystallized zircons that have been reworked in a sedimentary deposit display typologies that make it possible to identify the different igneous rock types present in the source region moreover the typological study can be associated with a single grain pb pb dating this twofold approach was applied to brioverian sedimentary rocks neoproterozoic iii to early palaeozoic in age from the central brittany domain armorican massif nw france it is proposed that these deposits inherited a major component from juvenile crustal materials end 540 1 4 to 6 3 reflecting the presence of igneous precursors with a dominantly mantle derived origin zircon sub types s19 s20 s24 s25 etc to which was added another component of crustal anatectic affinity zircon sub types s2 s6 s7 etc two igneous source regions are identified on the basis of the present study the anatectic granitic massifs of the mancellian batholith 540 ma along with a coeval ignimbritic suite of end proterozoic eocambrian age and the syn and post tectonic dioritic massifs 590 to 530 ma apart from these main sources of clastic supply it is very likely that sporadic contributions arose from basic to intermediate volcanic activity of mantle origin linked to the cadomian orogeny and from the icartian basement

identifying hydrologic flowpaths on arctic hillslopes using electrical resistivity and self potential shallow subsurface flow is a dominant process controlling hillslope runoff generation soil development and solute reaction and transport despite their importance the location and geometry of these flow paths are difficult to determine in arctic environments shallow subsurface flow paths are limited to a thin zone of seasonal thaw above permafrost which is traditionally assumed to mimic the surface topography we have used a combined approach of electrical resistivity tomography ert and self potential sp measurements to map shallow subsurface flow paths in and around water tracks drainage features common to arctic hillslopes ert measurements delineate thawed zones in the subsurface that control flow paths whereas sp is sensitive to groundwater flow we have found that areas of low electrical resistivity in the water tracks were deeper than manual thaw depth estimates and varied from the surface topography this finding suggests that traditional techniques might underestimate active layer thaw and the extent of the flow path network on arctic hillslopes sp measurements identify complex 3d flow paths in the thawed zone our results lay the groundwork for investigations into the seasonal dynamics hydrologic connectivity and climate sensitivity of spatially distributed flow path networks on arctic hillslopes

the use of element clay ratios assessing gains and losses of iron manganese and phosphorus in soils of sedimentary rocks on a landscape scale abstract quantitative statements about soil development on a landscape level of scale are difficult to work out especially in soils of stratified sediments this article presents an easily applicable method to infer gains and losses of fe mn and p in soilscapes developed on sedimentary rocks for this an element clay ratio was introduced the amounts of pedogenic cbd fe mn and total p in kg were calculated on a pedon basis i e for the volume under 1 m 2 down to the c horizon or any arbitrary depth in soils without a c horizon and divided by the amounts of clay in the same volume p ratio a comparison with the element clay ratio of the mixture of parent material s c ratio allows semi quantitative statements about elemental gains and losses due to solutional processes if only transformation processes are working p ratios should equal the c ratios in the case of fe and mn i e remaining constant with time any depletion or relative or absolute accumulation of the elements can be inferred from values which differ from this trend in the case of phosphorus the p ratios should decrease with time compared to the c ratios relative and absolute gains should result in minor differences between p and c ratios or p ratios exceeding c ratios the results of mass balance calculations on 27 pedons of southwestern germany with a broad amplitude of parameters fe mn p clay redoximorphism as well as the results of chronosequences of different climates parent materials and durations of soil development fits very well with the results of the ratio method developed by using the ratio method areas of depletion and accumulation can be identified in catenary studies as well as linkages between soils inferred e g interpedon translocations deductions of influences of man are possible too the assumptions and restrictions of the method were discussed in detail

mature thunderstorm cloud top structure and dynamics a three dimensional numerical simulation study abstract an anelastic three dimensional model is used to investigate the effects of vertical wind shear regime on cloud top structure and internal properties of mature isolated midlatitude thunderstorms four comparative experiments designated a through d are performed with varying shear profiles in otherwise identical initializations cases a c assume strong shear differing only in the veering of the low level hodograph moderate in a strong in b and none in c weak shear everywhere 40 as great as in c is assumed in case d the strong shear cases a c show moderately vigorous quasi steady mature updrafts with strong midlevel mesovortex couplets and marked anvil elongation along the net vertical shear vector differences are modest especially at cloud top though with low level hodograph curvature the updraft is enhanced and skewed toward the cyclonic right flank the weak shear case d shows a weaker and less persistent mature updraft than a c along with weaker midlevel rotation and a much more n

genesis of selected sandy soils in alberta canada as revealed by microfabric leachate and soil composition micromorphology and lysimeter studies were used to evaluate the nature and formation of the microstructures of some sandy soils in alberta canada the microstructures vary from monic or orthogranic grains uncoated related distribution pattern rdp in the ae horizons to chitonic or chlamydic rdp grains fully or partially coated in the matrix of the b horizons and to porphyric rdp grains embedded in fine mass in the nodules of the b horizons the various genetic transport processes are interpreted to be podzolization including the eluviation of organic matter and organometallic complexes of al and fe lessivage or the mobilization of phyllosilicates particulate fe oxides quartz and feldspar and possibly oxidation reduction processes accountable for the movement of fe2 there are indications in the study that iron oxides like goethite and ferrihydrite are active in the adsorption of organic matter and organo metallic complexes colloidal minerals in the leachates include globular ferrihydrite goethite opal phyllosilicates and very fine quartz chrysophycean stomatocysts and possibly amorphous aluminous materials

ecohydrological separation in wet low energy northern environments a preliminary assessment using different soil water extraction techniques ecohydrological studies in seasonally dry climatic regions have revealed isotopic separation of the sources of water used by trees and those that generate stream flow also referred to as the two water worlds hypothesis here we investigated whether similar separation occurs in a wet low energy northern latitude 57 environment in scotland for two common soil types histosols and podzols at three soil depths and at both forested with scots pine pinus sylvestris and non forested sites we compared the stable isotope composition of soil water held at increasing soil water tensions these were assessed by different soil water extraction techniques rhizon samplers mobile water centrifugation at different speeds representing different tensions and cryogenic extraction bulk water sampling occurred during a relatively dry summer water that was held at increasing tensions appeared more depleted than more mobile water consistent with older winter precipitation this pattern was independent of soil type vegetation cover and time during the growing season although there was a slight tendency towards less separation with soil depth nevertheless soil waters in this generally wet low energy environment exhibited only minor evaporative enrichment limited to the upper soil profile only furthermore stream water showed no deviation from the local meteoric water line preliminary sampling for tree xylem water suggested uptake of evaporated soil water from the near surface soil horizons upper 10 cm where fine root densities are concentrated for histosols in particular tree water appeared lagged in its isotopic composition compared to the soil water time series although more work is needed to fully test the two water worlds hypothesis our initial analyses did not provide clear evidence to support this in wet low energy northern environments copyright 2015 john wiley sons ltd

temperature influence on permeability of sioux quartzite containing mixtures of water and carbon dioxide co2 sequestration in aquifers and depleted hydrocarbon reservoirs is a promising option for reducing atmospheric co2 however its implementation requires understanding how co2 propagates and how it is stored in the reservoir co2 mixed with water exists in two forms an immiscible phase gas or liquid depending on the conditions of temperature and pressure and a dissolved phase a minor part of which reacts with h2o to form carbonic acid h2co3 the motion of co2 in the reservoir is therefore a two phase flow problem fluid rock chemical reactions may also be important but they are not considered here when several immiscible fluids occupy the pore space each phase may act as an obstacle to the motion of the others indeed experimental evidence from oil production vadose zone or co2 sequestration studies 1 demonstrates that permeability is affected by the presence of a second phase in the pore space the motion and spatial distribution of pore fluids like water and carbon dioxide are controlled not only by pore geometry and fluid pressure but also by the viscosity solubility surface tension and wetting characteristics of each fluid phase 2 properties that usually vary with temperature in the case of carbon dioxide and water the solubility of co2 is particularly sensitive to temperature thus temperature variations may also affect the distribution and flow of the phases in the pore space in this work we measured the effect of temperature variations on the permeability of a rock saturated with a mixture of carbon dioxide and water we used the oscillating pore pressure method oppm developed by kranz et al 3 and fischer et al 4 because it minimizes fluid flux and therefore is not expected to disturb the phase distribution in the pore space as much as a steadily flowing fluid would although the method was devised to measure permeability of rocks with a single fluid phase we can assess the effect of the second phase by comparing the permeability measurements made using a single fluid to those with a two phase mixture

chemical mineralogical and morphological characterization of three podzols developed on glacial deposits in northern europe the chemistry mineralogy and micromorphology of three soil profiles formed on genetically different quaternary deposits have been studied in relation to the podzolization process the soil materials showed quite uniform geochemical composition both within and between the study sites independent of great geographical distance and there is accumulation of sesquioxides in the bs horizons at all three sites mineralogical distributions derived from calculated normative compositions x ray diffraction analysis and thin section point counting show similar depth related trends the clay fractions at all three sites are dominated by a vermiculitic phase which contains variable degrees of polymeric hydroxy al in the interlayer space in most b horizons

solid liquid ree fractionation in the lateritic system of goyoum east cameroon the implication for the present dynamics of the soil covers of the humid tropical regions the ree th weathering geochemistry and mineralogy has been investigated in a lateritic soil cover in relation to the close hydrographical system at goyoum east cameroon the stutied area composed of gneissic hills covered by humid tropical forest belongs to the sanaga river basin and corresponds to a transition vegetation zone between rainforest and savannah a representative soil catena was taken as a reference zone close to the sanaga river the gneissic parent rock soil and groundwater samples have been cut off in pits in the lower part of the catena waters were also sampled both in brooks rich in organic matter and in the sanaga river all the waters were sampled seasonally during the rainy and dry periods the water rock interactions and the exportation of ree and th have been discussed as a function of the evolution of specific ratios considering th as the less mobile element during laterization variation of parent rock pr normalized ratios ln th pr vs depth show that the upper ferruginous horizons are depleted in ree while the basal saprolite presents accumulation zones which are differently located for ce and the other lrees the hrees are also depleted the la accumulations are located near the saprolite gneiss weathering front associated with negative ce anomalies ce ce 0 4 the ce accumulations inducing strong positive ce anomalies ce ce 4 are located in the upper saprolite beneath the ferruginous horizons all along the soil catena the secondary lree bearing minerals which reflect lree fractionation during incipient weathering of the gneiss are hydrous phosphates rhabdophane lreepo4 nh2o and cerianite ceo2 whose precipitation depends on the eh ph changes in the soil profiles on the other hand hree depletion is controlled by the dissolution of xenotime the major hree bearer in the parent gneiss in the 0 45 m filtered acidic groundwater ph 5 5 which have flooded the saprolite for a long residence time th contents are extremely low 0 th 10 ppt while lree contents are high 90 la 450 ppt in these filtered waters th seems to be strongly controlled by minerals i e thorianite which lead to its immobilization in the soil while lree remain in the soluble and or colloidal pools moreover the groundwaters show significant negative ce anomalies throughout the year 0 1 ce ce 0 4 the mobilization of lree except redox active ce results from the dissolution and or the mobilization in colloidal form of the secondary phosphates which may present major negative ce anomalies as indicated by the bulk soil analyses at the saprolite gneiss weathering front therefore the groundwaters have the signature of saprolitic materials we propose that the strong positive ce anomalies of the upper saprolite result from ancient weathering processes these processes would have led to much stronger ce iii ce iv dissolution reprecipitation conditions than those occurring at the present time in the saprolite in the 0 45 m filtered brook acidic blackwaters lree and th contents are high 100 th 400 ppt 400 la 1700 ppt in this organic matter rich environment lree and th are highly mobilized the colloial pool controls half of the whole lree th load the geochemical signature of these waters is independent of the gneissic parent rock and soil lree contents there is no ce anomaly this signature is similar to those of other organic rich rivers draining humid tropical ecosystems in the world in the 0 45 m filtered sanaga waters lree and th contents are lower than in the brooks 15 th 40 ppt 40 la 300 ppt these concentrations are dependent on the time and on the colloidal composition however 90 of these elements are mainly controlled by the suspended pool

adsorption of rare earth elements onto carrizo sand experimental investigations and modeling with surface complexation rare earth element ree adsorption onto sand from a well characterized aquifer the carrizo sand aquifer of texas has been investigated in the laboratory using a batch method the aim was to improve our understanding of ree adsorption behavior across the ree series and to develop a surface complexation model for the rees which can be applied to real aquifer groundwater systems our batch experiments show that ree adsorption onto carrizo sand increases with increasing atomic number across the ree series for each ree adsorption increases with increasing ph such that when ph 6 0 98 of each ree is adsorbed onto carrizo sand for all experimental solutions including when actual groundwaters from the carrizo sand aquifer are used in the experiments rare earth element adsorption was not sensitive to ionic strength and total initial ree concentrations in our batch experiments it is possible that the differences in experimental ionic strength conditions i e 0 002 0 01 m nacl chosen were insufficient to affect ree adsorption behavior however cation competition e g ca mg and zn did affect ree adsorption onto carrizo sand especially for light rare earth elements lrees at low ph rare earth element adsorption onto carrizo sand can be successfully modeled using a generalized two layer surface complexation model our model calculations suggest that ree complexation with strong surface sites of carrizo sand exceeds the stability of the aqueous complexes lnoh 2 lnso4 and lnco3 but not that of ln co3 2 or lnpo4 in carrizo groundwaters thus at low ph 7 3 where major inorganic ligands did not effectively compete with surface sites for dissolved rees free metal ion ln 3 adsorption was sufficient to describe ree adsorption behavior however at higher ph 7 3 where solution complexation of the dissolved rees was strong rees were adsorbed not only as free metal ion ln 3 but also as aqueous complexes e g as ln co3 2 in carrizo groundwaters because heavy rare earth elements hrees were preferentially adsorbed onto carrizo sand compared to lrees original hree enriched fractionation patterns in carrizo groundwaters from the recharge area flattened along the groundwater flow path in the carrizo sand aquifer due to adsorption of free and solution complexed rees copyright 2005 elsevier ltd

experimental evidence of lateral flow in unsaturated homogeneous isotropic sloping soil due to rainfall this paper describes laboratory experimental evidence for lateral flow in the top layer of unsaturated sloping soil due to rainfall water was applied uniformly on horizontal and v shaped surfaces of fine sand at rates about 100 times smaller than the saturated hydraulic conductivity flow regimes near the surface and in the soil bulk were studied by using dyes streamlines and streak lines and wetting fronts were visually studied and photographed through a vertical glass wall near wetting fronts the flow direction was always perpendicular to the fronts owing to dominant matrix potential gradients thus during early wetting of dry sloping sand the flow direction is directed upslope far above a wetting front the flow was vertical due to the dominance of gravity downslope flow was observed during decreasing rainfall and dry periods the lateral movement was largest near the soil surface and decayed with soil depth unstable downslope lateral flow close to the soil surface was attributed to non darcian flow due to variable temporal and spatial raindrop distributions the experiments verify the theory that predicts unsaturated downslope lateral flow in sloping soil due to rainfall dynamics only without apparent soil texture difference or anisotropy this phenomenon could have significant implications for hillside hydrology desert agriculture irrigation management etc as well as for the basic mechanisms of surface runoff and erosion

a hydropedological approach to quantifying groundwater recharge in various glacial settings of the mid continental usa data from six monitoring stations were combined with a soil water dynamics model hydrus 1d to achieve physically based estimates of shallow water table recharge in representative hydropedological settings of the glaciated midwestern u s a calibration involved inverse modeling that yielded optimized hydraulic parameters root mean square errors for modeled versus measured soil moisture contents were generally within 3 for all soil layers at the six study sites the optimized models also accurately simulated recharge values that corresponded to observed water table fluctuations optimized parameter values were consistent with estimates from a pedotransfer function lab analyses and field experiments forward modeling indicated that shallow water table recharge in mid continent glacial settings is approximately 35 of precipitation but interannual and monthly variability is significant soil parent materials and horizon characteristics influence recharge primarily through their control on ks with clay rich till parent materials producing values as low as 16 and coarse grained outwash parent materials producing values as high as 58 of precipitation during the three year study period distinct seasonality of recharge was observed with most recharge occurring in the winter seasonal mean of all sites was 66 of precipitation and lesser but interannually stable amounts in the spring 44 summer 13 and autumn 16 this research underscores the importance of incorporating pedological information into models of soil water dynamics and groundwater recharge 2015 the authors hydrological processes published by john wiley sons ltd

hydrology of subarctic canadian shield soil filled valleys the canadian shield landscape includes bedrock uplands and valleys infilled with soil a site near yellowknife in subarctic canada was studied to elucidate the hydrological behaviour of soil filled valleys a suite of hydrological processes was found to be important in the studied valley including snowmelt and rainfall ground frost development evaporation infiltration lateral inflow from adjacent uplands and surface and subsurface flows valley storage requirements during snowmelt are met by local meltwater infiltration but lateral inflows in the summer are needed to satisfy the storage before runoff can be generated from the valley the valleys perform three functions of collecting vertical and lateral water inputs retaining and losing the water held in storage and transferring water down the valley and generating local outflow unlike channel flows in humid areas runoff from the upper valley has to meet the storage demands of the lower valley segments often causing seepage loss along flow paths to render the flows intermittent a fill and spill runoff system is proposed in which the valley physiography results in a series of segments with varying storage conditions as water is supplied to the valley each segment has to be filled until its storage threshold for runoff is exceeded then subsurface or surface flows will be generated but these flows may be arrested to furnish water to satisfy the storage requirements of the segments downstream such a flow system applies also to other valleys in the shield environment

conceptualization of runoff processes using a geographical information system and tracers in a nested mesoscale catchment tracer investigations were combined with a geographical information system gis analysis of the 31 km2 girnock catchment cairngorm mountains scotland in order to understand hydrological functioning by identifying dominant runoff sources and estimating mean residence times the catchment has a complex geology soil cover and topography gran alkalinity was used to demonstrate that catchment geology has a dominant influence on baseflow chemistry but flow paths originating in acidic horizons in the upper soil profiles controlled stormflow alkalinity chemically based hydrograph separations at the catchment scale indicated that 30 of annual runoff was derived from groundwater sources similar contributions 23 36 were estimated for virtually all major sub basins 18o of precipitation mean 9 4 range 16 1 to 5 0 and stream waters mean 9 1 range 11 6 to 7 4 were used to assess mean catchment and sub basin residence times which were in the order 4 6 months gis analysis showed that these tracer based diagnostic features of catchment functioning were consistent with the landscape organization of the catchment soil and host hydrology of soil type maps indicated that the catchment and individual sub basins were dominated by hydrologically responsive soils such as peats histosol peaty gleys histic gleysols and rankers umbric leptosols and histosols soil cover in combination with a topographic index predicted extensive areas of saturation that probably expand during hydrological events thus providing a high degree of hydrological connectivity between catchment hillslopes and stream channel network this was validated by aerial photographic interpretation and groundtruthing these characteristics of hydrological functioning i e dominance of responsive hydrological pathways and short residence times dictate that the catchment is sensitive to land use change impacts on the quality and quantity of streamflows it is suggested that such conceptualization of hydrological functioning using tracer validated gis analysis can play an important role in the sustainable management of river basins copyright 2006 john wiley sons ltd

runoff generation in a steep tropical montane cloud forest catchment on permeable volcanic substrate 1 most studies to date in the humid tropics have described a similar pattern of rapid translation of rainfall to runoff via overland flow and shallow subsurface stormflow however study sites have been few overall and one particular system has received very little attention so far tropical montane cloud forests tmcf on volcanic substrate while tmcfs provide critical ecosystem services our understanding of runoff generation processes in these environments is limited here we present a study aimed at identifying the dominant water sources and pathways and mean residence times of soil water and streamflow for a first order tmcf catchment on volcanic substrate in central eastern mexico during a 6 week wetting up cycle in the 2009 wet season total rainfall was 1200 mm and storm event runoff ratios increased progressively from 11 to 54 with the increasing antecedent wetness conditions our isotope and chemical based hydrograph separation analysis showed increases of pre event water contributions to the storm hydrograph from 35 to 99 stable isotope based mean residence times estimates showed that soil water aged only vertically through the soil profile from 5 weeks at 30 cm depth to 6 months at 120 cm depth a preliminary estimate of 3 years was obtained for base flow residence time these findings all suggest that shallow lateral pathways are not the controlling processes in this tropical forest catchment rather the high permeability of soils and substrate lead to vertical rainfall percolation and recharge of deeper layers and rainfall runoff responses appeared to be dominated by groundwater discharge from within the hillslope

permeability evolution during non linear viscous creep of calcite rocks permeability storage capacity and volumetric strain were measured in situ during deformation of hot pressed calcite aggregates containing 10 20 and 30 wt quartz both isostatic and conventional triaxial loading conditions were used the tests were performed at confining pressure of 300 mpa pore pressures between 50 to 290 mpa temperatures from 673 to 873 k and strain rates of 3 10 5 s 1 argon gas was used as the pore fluid the initial porosities of the starting samples varied from 5 to 9 with higher porosity correlated to higher quartz content microstructural observations after the experiment indicate two kinds of pores are present 1 angular crack like pores along boundaries between quartz grains or between quartz and calcite grains and 2 equant and tubular voids within the calcite matrix under isostatic loading conditions the compaction rate covaries with porosity and increases with increasing effective pressure most of the permeability reduction induced during compaction is irreversible and probably owes to plastic processes as has been found in previous studies on hot pressed calcite aggregates permeability k is nonlinearly related to porosity o over small changes in porosity the two parameters are approximately related as k mathbf alpha mathbf phi n the exponent n strongly increases as porosity decreases to a finite value from about 4 to 6 depending on quartz content suggesting a porosity percolation threshold when subjected to triaxial deformation the calcite quartz aggregates exhibit shearenhanced compaction but permeability does not decrease as rapidly as it does under isostatic conditions during triaxial compaction the exponent n only varies between 2 and 3 non isostatic deformation seems to reduce the percolation threshold and in fact enhances the permeability relative to that at the same porosity during isostatic compaction our data provide constraints on the governing parameters of the compaction theory which describes fluid flow through a viscous matrix and may have important implications for expulsion of sedimentary fluids for fluid flow during deformation and metamorphism and melt extraction from partially molten rocks

organic complexation and translocation of ferric iron in podzols of the negro river watershed separation of secondary fe species from al species abstract the development of podzols in lateritic landscapes of the upper amazon basin contributes to the exportation of organic carbon and associated metals in the black waters of the negro river watershed we have investigated the distribution of feiii in the clay size fraction of eight organic rich horizons of waterlogged plateau podzols to unravel the weathering conditions and mechanisms that control its transfer to the rivers the speciation and amount of feiii stored in residual mineral phases of laterites or bound to organic compounds of weakly and well expressed podzols were determined by electron paramagnetic resonance spectroscopy combined with chemical analyses reducing conditions restrict the production of organo fe complexes in the subsoil b horizons of waterlogged podzols and most of the fe2 released from the dissolution of fe oxides is exported to the rivers via the perched groundwater however significant amounts of diluted feiii bound to organic ligands feiiiom and nano fe oxides are produced at the margin of the depression in the topsoil a horizons of weakly expressed podzols due to shorter periods of anoxia the downward translocation of organically bound metals from topsoil a to subsoil b horizons of podzols occurs in shorter distances for fe than it does for al this separation of secondary fe species from al species is attributed to the physical fractionation of their organic carriers in texture contrasted b horizons of podzols as well as to the effect of ph on metal speciation in soil solutions and metal binding onto soil organic ligands mostly for al this leads us to consider the topsoil a horizons of weakly expressed podzols as well as the subsoil bh horizon of better expressed ones as the main sources for the transfer of feiiiom to the rivers the concentration of feiiiom rises from soil sources to river colloids suggesting drastic biogeochemical changes in more oxygenated black waters of the negro river watershed the contribution of soil organic matter to the transfer of fe to rivers is likely at the origin of the peculiar fe isotope pattern recently recognized in podzolic environments

pre alpine mire sediments as a mirror of erosion soil formation and landscape evolution during the last 45 ka peat and lake sediments as well as a nearby soil catena were sampled to reconstruct the environmental history of a small infilled lake basin mire in the central alpine foreland of switzerland soil evolution is best regarded as discontinuous over time and conceptualised by progressive or regressive process phases we analysed the surrounding soils and used corresponding pedosignatures in the mire sediments to characterise notable phases of erosion and deposition we assumed that the mire sediments would reflect these phases that elemental composition major and minor compounds and rare earth elements rees would allow us to differentiate past processes and that progressive and regressive phases of soil development can be discerned although radiocarbon ages are equivocal it appears from pollen analyses that a lake was present here by c 45 ka bp after the retreat of the glacier from this area following the lgm continuous sedimentation occurred until a mire developed during pleistocene holocene transition this transition period was accompanied by more intense erosion as characterised by chemical signatures a stable phase developed between c 10 5 ka bp giving rise to progressive soil evolution between 5 and 4 ka bp evidence appears for several erosional phases predominantly detectable at the margin of the mire these erosion phases coupled with accumulation in the mire are even more evident after 4 ka bp and especially after 2 1 ka bp based on soil investigations elemental fluxes are detected along the slopes with distinct accumulations at the footslope evidence for anthropogenic influences and subsequent regressive soil formation phases appear in this pre alpine landscape about 5 ka bp neolithic early bronze age which appears to intensify after 2 1 ka bp roman period to present multi elemental signatures enabled us to identify the important geochemical processes that have occurred here together with radiocarbon and pollen analyses we placed these processes in a logical temporal context the use of lacustrine lake or mire sediments has great potential to decipher and detail the surrounding landscape history and soil evolution of this region of switzerland

water transport and tracer mixing in volcanic ash soils at a tropical hillslope a wet layered sloping sponge andosol soils formed in volcanic ash provide key hydrological services in montane environments to unravel the subsurface water transport and tracer mixing in these soils we conducted a detailed characterization of soil properties and analyzed a 3 year data set of sub hourly hydrometric and weekly stable isotope data collected at three locations along a steep hillslope a weakly developed 52 61 cm depth highly organic andic ah horizon overlaying a mineral c horizon was identified both showing relatively similar properties and subsurface flow dynamics along the hillslope soil moisture observations in the ah horizon showed a fast responding few hours rooted layer to a depth of 15 cm overlying a perched layer that remained near saturated year round the formation of the latter results from the high organic matter 33 42 and clay 29 31 content of the ah horizon and an abrupt hydraulic conductivity reduction in this layer with respect to the rooted layer above isotopic signatures revealed that water resides within this soil horizon for short periods both at the rooted 2 weeks and perched 4 weeks layer a fast soil moisture reaction during rainfall events was also observed in the c horizon with response times similar to those in the rooted layer these results indicate that despite the perched layer which helps sustain the water storage of the soil a fast vertical mobilization of water through the entire soil profile occurs during rainfall events the latter being the result of the fast transmissivity of hydraulic potentials through the porous matrix of the andosols as evidenced by the exponential shape of the water retention curves of the subsequent horizons these findings demonstrate that the hydrological behavior of volcanic ash soils resembles that of a layered sponge in which vertical flow paths dominate

importance of thermochemical pressurization in the dynamic weakening of the longmenshan fault during the 2008 wenchuan earthquake inferences from experiments and modeling 1 we determined the internal structure and mineral composition of the yingxiu beichuan fault zone at the zhaojiagou exposure and measured frictional and transport properties of the fault rocks collected to gain a better understanding of dynamic weakening mechanisms during seismic fault motion this fault is a major fault in the longmenshan fault system that caused the 2008 wenchuan earthquake the exposure studied is located midway along the surface rupture close to where the largest coseismic displacement occurred high velocity friction experiments reveal exponential slip weakening from a peak friction toward a steady state value slip weakening is more pronounced for water dampened gouge than dry gouge suggesting thermal pressurization the fault gouge has a very low permeability 10 21 m2 at 165 mpa effective pressure and is surrounded by fault breccia with a permeability of 10 19 to 10 17 m2 grading into less permeable fractured country rocks the fault zone thus exhibits a conduit barrier structure allowing fluid flow only in the breccia zone we numerically modeled coseismic slip weakening including thermal pressurization and mineral dehydration decarbonation basing our calculation on measured frictional and transport properties and on the slip history inferred for the wenchuan earthquake the results indicate that 1 thermochemical pressurization played an important role in causing dynamic slip weakening 2 the slip weakening distance is similar to the seismologically determined values and 3 pore pressures might have exceeded the normal stress thus maintaining temperatures below 600 c interestingly enough heat was generated to fully remove and thermally pressurize the interlayer water from smectite contributing an excess pore pressure of 6 mpa in addition we found that the incorporation of state dependent fluid properties predicts much more efficient fluid pressurization than using constant properties the dramatic weakening predicted probably offers a compelling explanation for the large coseismic displacement and slip acceleration observed near beichuan city

the dynamics of si cycling during weathering in two small catchments in the black forest germany traced by si isotopes abstract silicon stable isotopes have emerged as a powerful proxy to investigate weathering because si uptake from solution by secondary minerals or by the vegetation causes significant shifts in the isotope composition in this study we determined the si isotope compositions of the principle si pools within two small catchments located on sandstone and paragneiss respectively in the temperate black forest germany at both settings clay formation is dominated by mineral transformation preserving largely the signature of parental minerals with 30si values of around 0 7 bulk soils rich in primary minerals are similar to bulk parental material with 30si values close to 0 4 topsoils are partly different because organic matter degradation has promoted intense weathering leading to 30si values as low as 1 0 water samples expose highly dynamic weathering processes in the soil zone 1 after spring snowmelt increased release of doc and high water fluxes trigger clay mineral dissolution which leads to 30si values down to 0 7 and 2 in course of the summer si uptake by the vegetation and secondary mineral formation drives dissolved si to typical positive 30si values up to 1 1 groundwater with 30si values of around 0 4 records steady processes in bedrock reflecting plagioclase weathering together with kaolinite precipitation an isotope mass balance approach reveals incongruent weathering conditions where denudation of si is largely driven by physical erosion erosion of phytoliths contributes 3 to 21 to the total si export flux which is in the same order as the dissolved si flux these results elucidate the si dynamics during weathering on catchments underlain of sedimentary origin prevailing on the earth surface and provide therefore valuable information to interpret the isotope signature of large river systems

solid speciation and fractionation of rare earth elements in a spodosol profile from northern sweden as revealed by sequential extraction a sequential extraction has been carried out on seven soil samples from a spodosol profile in till with granitic composition the soil profile was sampled in northern sweden five fractions were selected for extraction a ch 3coona extractable exchangeable adsorbed carbonate b na 4p 2o 7 extractable labile organics c 0 25 m nh 2oh hcl extractable amorphous fe oxyhydroxides mn oxides d 1 m nh 2oh hcl extractable crystalline fe oxides and e kclo 3 hcl extractable organics and sulphides extracted rare earth elements ree were determined with high resolution icp ms in addition to the soil stream water suspended particulate matter was also analysed for ree total concentrations in the soil samples show that the ree have been fractionated during weathering in the acidic ph 4 28 e horizon all ree are depleted relative to the unweathered till the depletion decreases with increasing atomic number also in the b horizon ph 5 86 the ree are depleted although to a lesser extent compared to the e horizon secondary phases in the b horizon fractionate the ree in different ways rare earth elements extracted in extractions a and c were enriched in the intermediate ree relative to heavy and light ree if normalized to local till in extractions b and d the heavy ree were enriched relative to the light ree and in extraction e a large enrichment of light ree relative to heavy ree was found stream water suspended particulate matter is enriched in all ree relative to local till the light ree are more enriched than the heavy ree normalized la lu ratios in the suspended matter ranged from 1 5 to 2 4 and were negatively correlated with stream water discharge as well as with content of detrital inorganic matter in the suspended load the only extracted phase that potentially can explain the high normalized la lu ratio in the suspended matter is the phase extracted in extraction e which has a ratio of 2 0 4 2 the normalized la lu ratio for the rest of the extractions ranged from 0 5 to 1 2 it is concluded that organic matter seems to be important for the particulate transport of ree in northern coniferous areas

storage dynamics in hydropedological units control hillslope connectivity runoff generation and the evolution of catchment transit time distributions we examined the storage dynamics and isotopic composition of soil water over 12 months in three hydropedological units in order to understand runoff generation in a montane catchment the units form classic catena sequences from freely draining podzols on steep upper hillslopes through peaty gleys in shallower lower slopes to deeper peats in the riparian zone the peaty gleys and peats remained saturated throughout the year while the podzols showed distinct wetting and drying cycles in this region most precipitation events are 80 of flow even in large events reflecting the displacement of water from the riparian soils that has been stored in the catchment for 2 years these riparian areas are the key zone where different source waters mix our study is novel in showing that they act as isostats not only regulating the isotopic composition of stream water but also integrating the transit time distribution for the catchment

rare earth elements as reactive tracers of biogeochemical weathering in forested rhyolitic terrain article rareearthelements rees were evaluatedaspotentialtracers of biogeochemicalweathering atpedon hillslope and catchment scales in the jemez river basin critical zone observatory jrb czo valles caldera national pre serve nm usa we investigated time series of ree patterns in precipitation soil pore water groundwater and stream water and related these data to ree composition of soil rock and atmospheric dust ree signatures in stream waters are dynamic reflecting processes that occur along hydrologic flowpaths during transport to the stream including organic matter complexation primary and secondary mineral weathering water soil bedrock interaction and atmospheric deposition strong compositional similarities for the ree between soil waters and stream waters during the initial snowmelt are consistent with shallow subsurface flows to streams most bio

chemical weathering in the drainage basin of a tropical watershed nsimi zoetele site cameroon comparison between organic poor and organic rich waters abstract this study deals with the weathering processes operating at the scale of a small catchment nsimi zoetele cameroon and is focused on the role of organic colloids on mineral weathering and transport of elements in natural waters samples of river spring and groundwaters from nsimi zoetele were filtered through membranes of decreasing pore size 0 22 m 0 025 m or 300 000 da 5000 da to separate colloidal fractions from the truly dissolved one major and trace elements and dissolved organic carbon doc were analysed in each fraction two kinds of waters can be distinguished in the catchment clear and coloured waters clear waters exhibit low concentrations of major and trace elements and doc elements are carried in these solutions in a true dissolved form except al and rare earth elements rees by contrast the higher abundances of al fe and trace elements in coloured waters are controlled by the colloidal fraction thermodynamic equilibrium calculations show that clear waters are in equilibrium with kaolinite and iron oxi hydroxide which are major minerals in the weathered soil for coloured waters the aqueous speciation of ca mg cu fe al la and th was calculated taking into account the complexes with humic acids speciation calculations for cu fe al la th show a strong complexation with humic acids in good agreement with the results of the filtration experiments by contrast although filtration experiments show a strong control of major cations by organic matter for example 75 for ca speciation calculations reveal that their complexes with humic ligands do not exceed a few percent of total dissolved elements this discrepancy is explained as an artefact induced by the organic colloids and occurring during the filtration procedure finally both filtration experiments and speciation calculations show that organic matter plays an important role in natural doc rich waters organic acids increase significantly the dissolution rates of silicates and oxi hydroxides and thus the amounts of solutes and of complexed elements leaving the catchment

bedrock infiltration estimates from a catchment water storage based modeling approach in the rain snow transition zone summary estimates of bedrock infiltration from mountain catchments in the western u s are essential to water resource managers because they provide an estimate of mountain block recharge to regional aquifers on smaller scales bedrock infiltration is an important term in water mass balance studies which attempt to estimate hydrologic states and fluxes in watersheds with fractured or transmissive bedrock we estimate the a daily time series of bedrock infiltration in a small catchment in the rain snow transition zone in southwest idaho using the difference between measured stream discharge and modeled soil drainage the accuracy of spatial patterns in soil water storage are optimized rather than the more common approach of minimizing error in integrated quantities such as streamflow bedrock infiltration is estimated to be 289 mm 50 mm for the 2011 water year which is 34 12 of the precipitation 95 confidence soils on the southwest facing slope drain more often throughout the snow season but the northeast facing slope contributes more total soil drainage for the water year peaks in catchment soil drainage and bedrock infiltration coincide with rain on snow events

mass fluxes and clay mineral formation in soils developed on slope deposits of the kowarski grzbiet karkonosze mountains czech republic poland abstract weathering mineral formation and transformation processes along slopes are complex in cool mountainous regions undisturbed soil development with a strong vertical leaching element may abruptly change as a result of erosion accumulation lateral water fluxes and aeolian input we investigated soils in the eastern karkonosze mountains that have developed on silicatic slope deposits to date illite vermiculite and chlorite are the minerals that have been detected in the clay fraction although the climate and parent material should be favourable for the formation of smectites expandable phases were not verified so far we investigated if expandable phases could be detected and how they related to elemental fluxes along a short slope sequence 1142 1268 m a s l on the border between the czech republic and poland mass balance calculations indicated intensive mineral weathering together with a significant leaching of mg al ca and mn on the shoulder and foot slope positions in the middle zone which has a concave or undulating surface shape however the mass balances of several elements na k al p revealed a less pronounced leaching corresponding to a lower degree of podsolization and in some cases even accumulation at all sites mass balance calculations and detected soil minerals e g the increase in illite towards the surface together with an increase in al and k indicate some aeolian input kaolinite was detected in all soil horizons its concentration slightly increased towards the soil surface together with the pronounced leaching of ca part of kaolinite originates from plagioclase weathering besides being a weathering product of primary minerals part of the kaolinite is inherited from the parent material and probably is also due to aeolian input in all soils illite was being transformed into vermiculite and smectites through regularly interstratified illite smectite phases in addition the content of chloritic components which increases with depth indicated their concurrent weathering and transformation into smectites amphibole also may have acted as a source of smectites not all smectite is being actively formed in the soil most likely due to slope processes cover beds that affected even the subsoil some smectite has been transferred along the slope part of the smectite also seems to derive from the parent material active formation of expandable clay minerals is related to convex and planar landscape forms this relationship suggests intense element leaching inheritance from the parent material and cover bed mixing processes have contributed to the presence of smectite along the slope zones with predominant vertical transport shoulder foot slopes may repeatedly be interchanged with zones dominated by lateral transport undulating slope concave forms

the occurrence soil parameters and genesis of rubified soils fuchserden of northeastern germany abstract the local occurrence of red subsoils on the late pleistocene sandy deposits of the northern european lowlands invites investigation into the formation and paleoenvironmental significance of these soils according to the world reference base for soil resources wrb these soils are classified as rhodic brunic arenosols or chromic brunic arenosols however because of their unclear origins these soils are still not considered in the german guidelines for soil mapping we aim to characterize the genesis of these rubified soils by combining pedological findings with chemical analyses and micromorphological studies at four sites in southeastern brandenburg germany our novel analytical approach differentiates pedogenic iron hydr oxides using a combination of fourier transform infrared multiple internal reflection ftir mir spectroscopy and sequential sample heating from 21 c to 100 c 250 c 500 c and 950 c together with a comparison of synthetic iron hydr oxides the results of this analytical approach demonstrate that the mineralogy of these rhodic brunic arenosols and chromic brunic arenosols are characterized mainly by hematite some goethite and minor amounts of maghemite are also present our results confirm recent findings from jankowski 2013 that rubification is not primarily a relict process in central european soils consequently the german guidelines for soil mapping require revision the high total iron contents in the rubified soils suggest strongly that the iron is allochthonous in origin emphasizing the importance of lateral inputs of iron compounds in the genesis of these soils this finding is highly consistent with the translocation catena concept sommer and schlichting 1997 i e the rhodic brunic arenosols and chromic brunic arenosols studied here formed due to inputs of allochthonous compounds these rubified soils examined in this study share some genetic features with other soils described from central europe such as the lockerbraunerden or the ockererden further research should focus on these commonalities and compare the genetic pathways of such soils to support the argument that these soils should be considered in a separate soil class in the german guidelines for soil mapping

lithological discontinuities in podzols developed from sandstone cover beds in the stolowe mountains poland abstract podzols developed within so called cover beds were examined on a slope built of cretaceous sandstones in sw poland their typical feature is an easily recognizable stratification of regolith evidenced in the dichotomy of soil texture and dense subsoil heterogeneity of soil profiles is manifested in vertically differentiated sequence 1 dense skeletal and massive layer comprising usually bs and bc horizons sometimes bhs bh horizons with strong platy structure is overlain by 2 the uppermost relatively young layer consisting of loose sandy material bearing single coarse fragments of a less weathered sandstone hosting ae e and partially bh horizons this remarkable layering of slope sediments caused a distinctive lithological discontinuity at the boundary of e and b horizons evidenced by the differences in i rock fragments content ii degree of rock clast weathering iii distribution of highly resistant minerals and iv fluctuation of silt and sand fractions within profiles lithological discontinuity influences both the lateral podzolization and the thickness and depth of albic and spodic horizons along the slope catena regarding the temporal order the lowermost layer was influenced by periglacial conditions at before the boreal presumably as the surface layer high score of pollen grains the age of surficial sandy layer based on pollen record could be established at subatlantic and correlated with forest cutting and intensive surface erosion charcoal dating 960 30 cal bp neither layers that originated from the eolian processes were distinguished nor any admixture of allochthonous material was found therefore typical middle and upper periglacial cover beds are not present in this sequence in any case podzols that were formed from the slope sediments in the stolowe mountains are polygenetic and of the holocene age

lateral water flux in the unsaturated zone a mechanism for the formation of spatial soil heterogeneity in a headwater catchment measurements of soil water potential and water table fluctuations suggest that morphologically distinct soils in a headwater catchment at the hubbard brook experimental forest in new hampshire formed as a result of variations in saturated and unsaturated hydrologic fluxes in the mineral soil previous work showed that each group of these soils had distinct water table fluctuations in response to precipitation however observed variations in soil morphology also occurred above the maximum height of observed saturation variations in unsaturated fluxes have been hypothesized to explain differences in soil horizon thickness and presence absence of specific horizons but have not been investigated explicitly we examined tensiometer and shallow groundwater well records to identify differences in unsaturated water fluxes among podzols that show distinct morphological and chemical differences the lack of vertical hydraulic gradients at the study sites suggests that lateral unsaturated flow occurs in several of the soil units we propose that the variations in soil horizon thickness and presence absence observed at the site are due in part to slope parallel water flux in the unsaturated portion of the solum in addition unsaturated flow may be involved in the translocation of spodic material that primes those areas to contribute water with distinct chemistry to the stream network and represents a potential source sink of organometallic compounds in the landscape

using long term data sets to understand transit times in contrasting headwater catchments summary long term tracer data collected over an 8 year period were analyzed to explore the transit times of two small 1k m 2 contrasting headwater catchments in the uplands of scotland at loch ard the catchment was characterized by low permeability gleyed soils overlying metamorphic geology at sourhope more freely draining podzolic soils were dominant which mantled fractured and faulted volcanic rocks hydrometric data and chemically based hydrograph separations indicated that loch ard was a flashy catchment dominated by runoff processes in the upper soil horizons in contrast around 77 of annual flow at sourhope was sustained by well buffered groundwater sources weekly cl time series in precipitation and stream flow revealed similar variability in inputs at both sites but much greater damping in outputs at sourhope despite this both catchments filtered white noise frequencies in precipitation inputs into 1 f outputs these input output relationships were modeled with a range of transit time distributions ttd at the responsive loch ard catchment mean transit times mtt for the study period were estimated at 135 202 days models based on a gamma distribution or two parallel linear reservoirs were best able to capture the short and long term fluctuations in stream water in response to input variations at sourhope the highly damped tracer signal in stream waters was poorly captured by all the ttds used resulting mtt estimates of 1830 1970 days are based on weak model fits and poorly identifiable parameter sets indicating that natural tracers such as cl are inadequate for catchments where mtts are greater than a few years at both sites estimates of mtt using moving windows over the 8 year data sets revealed sensitivity to precipitation amounts and the length of monitoring period it is concluded that time series of around 4 years are required to adequately constrain mtt estimates

catena linking of landscape geochemical processes and reconstruction of pedosedimentogenesis a case study of defensive constructions of the mid 17th century south russia abstract the catena concept along with previously proposed meanings of this term has recently acquired a soil evolutionary content the prospects of wider special and chronological study of dated pedotopocatenas include the possibility of a more detailed analysis of the mutual dependence of soil geomorphological relationships through distinguishing relatively homogeneous climatic stages of pedogenesis and denudation with this purpose the present study comprised earthen defensive constructions which within the rampart ditch system combine erosive trans accumulative catenas and accumulators of pedolithosediments the goal was to develop a system of the most information rich pedogenetic indicators to reconstruct the dynamics of erosion accumulative processes on the basis of dated earthen defensive constructions of a historical period using the example of a frontier rampart within a ditch from the mid 17th century soil samples were collected within the limits of the erosion and trans accumulative catenas as well as in the closing alignment of the ditch over the vertical profile in eight strata of pedosediments of up to 1 m high the granulometric composition concentration of macroelements and trace elements 25 metals and oxides in soils and in particles with sizes 0 01 mm in size the content of organic carbon and its qualitative composition the sum of the elements accumulated in the soil p ca k mg mn cu as well as the geochemical ratios which reflect the processes of leaching can serve as palaeogeographic tracers of the climatic variability at the level of intra secular changes under forest steppe conditions the history of the formation of pedosediments over 3 5 centuries in the forest steppe zone of eastern europe comprises two wet periods 1890 1935 1976 2013 when the average annual rates of pedosedimentogenesis were similar 2 80 2 85 mm yr 1 and two periods of geomorphological lull and a xeromorphic climatic condition span 1821 1890 and 1666 1741 these periods correspond to diminution of the average rate of accumulation of sediments down to 2 47 mm yr 1 the results of the present study suggest the need for purposeful research and wide inclusion of dated sites of the anthropogenic relief formation with flow geochemical series over the topographic gradient into studies of soil geomorphologic interrelations and calibration of mathematic models of natural processes using on site data

a review on the potentiality of rare earth elements to trace pedogenetic processes abstract this review aims at considering the use of rees to trace pedogenetic processes in order to quantify the respective contribution of the successive processes on pedogenesis we first consider the origins and contents of rees in soils to assess their natural occurrence and tackle the common data treatment used to interpret their concentrations we review subsequently the impact of the different pedogenetic processes on the fate of rees in soils from their release into a soil solution by primary mineral heavy minerals phosphates silicates and carbonates dissolution during weathering to their fixation on or into main ree bearing secondary minerals clay minerals fe mn oxides and carbonates then their mobilization by plant recycling and organic matter and finally the impact of argilluviation and redox processes on their fractionation we conclude that rees much more than other trace elements can interestingly trace the considered processes that are encountered in a large diversity of non polluted soils arising from diverse parent materials weathering generally fractionates rees and accounts for a significant part of the variation in the initial ree stock of the soils plant recycling induces a weak mobilization of rees and their accumulation in topsoil argilluviation can be traced using the mree enrichment and the eu anomaly of the clay minerals redox processes can be traced by the ce anomaly caused by the precipitation of cerium on mn oxides to use rees as tracers of pedogenetic processes we recommend to i precisely characterize the ree bearing minerals ii adapt the choice of reference s for normalization and iii perform mass balance calculations

convection waves observations of gravity wave systems over convectively active boundary layers widespread gravity wave systems have been found to exist over convectively active boundary layers cbls in the presence of vertical wind shear in contrast to mountain waves these convection waves occur over flat terrain and are ubiquitous over fields of shallow fair weather cumuli or clear air thermals they extend vertically to at least 9km a m s l probably to the tropopause first discovered by glider pilots as thermal waves they have now been systematically investigated by research aircraft during the ncar convection wave project which also incorporates an effort in numerical simulation the flight results are reported in this paper while the numerical simulations are described in a companion paper typical wavelengths of convection waves were found to range from 5 to 15 km average 9 km and typical vertical motion amplitudes from 1 to 3 m s 1 in all cases vertical wind shear exceeded 3 10 3s 1 under these conditions cloud tops were measured to move with relative velocities of 8 to 10 m s 1 against their environment hence they present an obstacle to the surrounding airflow the analogy to mountainous obstacles launching gravity waves into the atmosphere is suggestive and borne out by the aforementioned numerical simulations which describe this process step by step the interaction between the cbl and the overlying stable layers is studied by spectral and cross spectral analysis of aircraft data including coherence and phase relations between wave motions and cloud population underneath consideration is given to other potential sources of the observed gravity waves at this stage the conclusions of our pilot study may be considered tentative some implications for further research are also discussed

the influence of topography on time and space distribution of soil surface water content the distribution of water content in time and space at the soil surface has been investigated on a small farmland catchment 1 3 km2 from four field surveys corresponding to different moisture statuses for each survey about 400 samples were collected at the soil surface at a depth of 5 cm along ten axes parallel to the greatest slope the relationship between the measurements and the topography has been analysed the structure of the data is well explained by a topographic index referring to the downslope conditions and defined as the elevation difference between the sample point and the stream point corresponding to the outlet of the water pathway derived from the digital elevation model dem this index can be considered as an hydraulic head at least for saturated conditions a threshold for this index allows two domains within the catchment to be distinguished an upper domain where the water content is nearly constant and varies slowly and a lower domain where moisture status increases and is highly variable the spatial distribution of these two domains is well correlated to the spatial distribution of the soils thus both topography and the spatial distribution of soil appear to control the spatial distribution of surface water content at the 1 km2 scale 1997 by john wiley sons ltd

lateral podzolization in a sandstone catchment a sandstone catchment of the cool perhumid black forest germany was studied with respect to podzolization processes on a landscape scale soil mapping along a steep slope 25 revealed spodosols with thick e horizons combined with thin spodic horizons in the upper catchment area lowermost parts of the landscape showed thinnest e and thickest bhs horizons this catenary trend was quantified by a non linear increase of the illuviation eluviation ratio of podzolization ierpodzol soil texture pedogenic oxides feo fed alo mnd ph cacl2 corg and mineralogical composition of the clay and medium sand fraction were determined in six representative pedons chemical analysis matched morphology in that very low contents and mass densities of feo fed alo and mnd were found in upslope soils the distal pedons were 2 5 fold higher in these elements the catenary trends corresponded to a downslope increase in ph as well as organic carbon in mineral soils mineralogical analysis showed a decrease in feldspar weathering and an increase in hydroxy interlayered vermiculites towards the downslope soils the morphological chemical and mineralogical results led to the conclusion of a process sequence of i an upslope mobilization and depletion of iron manganese and aluminum e spodosols ii a lateral translocation 30 of catchment discharge occurred as interflow and iii a downslope immobilization resulting in a relative or absolute accumulation of the translocated soil compounds bs spodosols the immobilization probably was controlled by an admixture of fe and base richer rocks into the parent material downslope the concept of lateral podzolization developed in a granite landscape was confirmed in the sandstone area studied

the evidence of lateral podzolization in sandy soils of northern poland abstract evidence of slope scale element translocation lateral podzolization has been documented in sandy areas of northern poland accumulative soils enriched with organic matter iron aluminum and manganese entic podzols have been found at the bottom of closed small depressions in inland dune fields and undulated surfaces of glaciofluvial terraces together with the surrounding weakly or moderately developed podzolic soils albic arenosols haplic podzols entic podzols form regular toposequences and seem to be geochemically linked in the light of chemical micromorphological and sem eds analyses the whole solum of the soils under study exhibit diagnostic features of the illuvial spodic horizon however they do not have an eluvial albic horizon landscape position and features of the studied soils suggest inter pedon translocation of organic matter iron and aluminum as the concept of entic podzol genesis furthermore high values of fe d fe t and fe o fe d ratios in their solum can be interpreted as evidence of allochtonous character of iron accumulation the results of this study show that the lateral podzolization process can be common even along slopes built from loose permeable sandy deposits where one would not expect any effective intra layer solution flow organic matter and compounds illuviated to the bhs horizon are the probable factors limiting percolation and modifying the direction of solutions movement on slopes of more complex morphology small closed depressions act as geochemical traps where compounds leached from the upper slope soils can accumulate radiocarbon dating carried out on a buried entic podzol found in one of the profiles shows that the process has continued for more than 1200 years

experimental investigation into the scale dependence of fluid transport in heterogeneous rocks we investigated the dependence of hydraulic properties on the spatial scale of intrinsic and artificial heterogeneity applying harmonic pore pressure testing to two varieties of fontainebleau sandstone at various periods and effective pressures blocks with porosities of about 5 and 8 were chosen exhibiting a permeability of about 2 10 19 and 1 10 13 m2 respectively the permeability of the less permeable variety strongly depends on sample size artificial heterogeneous rock samples were prepared by stacking pieces of the two sandstone varieties perpendicular and parallel to the main flow direction the perturbation of the fluid flow owing to the interfaces between pieces of the same variety is controlled by the orientation of and subordinately by the effective stress on the interfaces constraints on conduit geometry derived from the effect of interfaces indicate that interconnectivity is more important than pore radius at the lower porosity the effective permeability of alternating stacks of the two varieties differs tremendously for the two interface orientations arithmetic and harmonic averages coincide with the effective properties parallel and perpendicular to the main flow respectively when the oscillation period is varied two regimes are observed one with constant permeability at long periods and a second with decreasing permeability for decreasing period at short periods order of magnitude considerations of penetration depth suggest that this period dependence may be related to heterogeneity

predictive modeling of bedrock outcrops and associated shallow soil in upland glaciated landscapes abstract identifying the areal extent of bedrock outcrops and shallow soils has important implications for understanding spatial patterns in vegetation composition and productivity stream chemistry gradients and hydrologic and soil properties of landscapes manual methods of delineating bedrock outcrops and associated shallow soils are still commonly employed but they are expensive to implement over broad areas and often limited by representation of polygon units few studies have automated the delineation of bedrock outcrops these focused on delineation approaches in landscapes with rapidly eroding hillslopes and sparse vegetation the objectives of this study were to assess the accuracy of visually interpreting high resolution relief maps for locating bedrock outcrops and associated shallow soil boss

holocene forest transformations in sandstone landscapes of the czech republic stand scale comparison of charcoal and pollen records stand scale palaeoecology in sandstone landscapes provides insight into contrasting holocene forest succession trajectories sharp geomorphological gradients in this investigated area which in add