variations in the discharge and organic matter content of stalagmite drip waters in lower cave bristol six drip waters which were actively depositing stalagmites in lower cave bristol were analysed both for discharge and luminescence properties drip discharges were determined for two different years and show a complex response to surface precipitation variations inter annual variability in drip discharge is demonstrated to be significantly higher than intra annual variability and discharge was demonstrated both to increase and decrease non linearly with increased precipitation drip waters demonstrate a correlation between their luminescence intensity and drip discharge with increased luminescence in winter as more organic matter is flushed through the aquifer the strength of the relationship between luminescence intensity and discharge increases with increased discharge the results presented here have implications for the palaeoenvironmental interpretation of annual growth laminae and the growth rates of stalagmite samples 1997 john wiley sons ltd

in situ estimates of net sediment flux per swash reply to discussion by te baldock of measurement of wave by wave bed levels in the swash zone abstract this paper replies to te baldock s discussion coastal eng 56 2009 380 381 of measurement of wave by wave bed levels in the swash zone by turner et al coastal eng 55 2008 1237 1242 we address and extend the comparison and discussion of ultrasonic bed level sensors and buried pressure transducers to obtain estimates of the beach face elevation within the swash zone we demonstrate the use of the former method to obtain many and continuous every time the beach face is exposed in situ estimates of net sediment flux per swash

reconstructing past seawater mg ca and sr ca from mid ocean ridge flank calcium carbonate veins proxies for past seawater chemistry such as mg ca and sr ca ratios provide a record of the dynamic exchanges of elements between the solid earth the atmosphere and the hydrosphere and the evolving influence of life we estimated past oceanic mg ca and sr ca ratios from suites of 1 6 to 170 million year old calcium carbonate veins that had precipitated from seawater derived fluids in ocean ridge flank basalts our data indicate that before the neogene oceanic mg ca and sr ca ratios were lower than in the modern ocean decreased ocean spreading since the cretaceous and the resulting slow reduction in ocean crustal hydrothermal exchange throughout the early tertiary may explain the recent rise in these ratios

climate information imprinted in oxygen isotopic composition of precipitation in europe abstract in this study we analyze the interannual variability of the oxygen isotopic composition of winter precipitation 18 o prec over europe and investigate its related climate information for this purpose we compare winter temperature precipitation and 18 o prec modeled by the atmospheric general circulation model echam5 wiso with different observational datasets over europe in general the model and data results are very similar for the present day climate and the modeled 18 o prec is matching the global network of isotopes in precipitation station data echam5 wiso only slightly underestimates the temperatures over europe mean difference 0 4 c the mean european precipitation amount is very similar 85 mm month however in central western europe the modeled precipitation is overestimated by up to 30 mm month we also evaluate the large scale circulation associated with the regional 18 o prec values by correlating the north atlantic oscillation nao index to modeled 18 o prec fields we show that the nao pattern is most pronouncedly imprinted in 18 o prec over central western europe consistent with observations we demonstrate for an example location near a stalagmite site in central germany how local isotope related climate variables are related to large scale european climate variability we find that in both the model results and the data present day winter variability of local 18 o prec is strongly related to atmospheric circulation remote sea level pressure fields and much less to the local and remote temperature or precipitation fields the simulated correlation pattern resembles the nao pattern but is tilted to the east due to the combined effect of temperature and precipitation

swash infiltration exfiltration and sediment transport field measurements of vertical pore pressure gradients within the bed are used to quantify instantaneous 8 hz rates of swash infiltration exfiltration across the beach face cyclic infiltration exfiltration is associated with individual swash events with observed vertical flow rates o 10 3 m s rates of net swash groundwater exchange i e through bed flow integrated over several swash cycles are two orders of magnitude smaller at the timescale of individual swashes vertical pore pressure gradients within the beach face are much greater than horizontal pore pressure gradients this permits application of the numerical solution of darcy s law for one dimensional vertical flow to model fluctuating pore pressures and hence vertical through bed flow vertical flow through a porous bed modifies sediment mobility in at least two ways 1 seepage forces change the effective weight of surficial sediments and 2 boundary layer thickening or thinning result in altered bed shear stresses by considering these two opposing effects separately a new shields parameter is derived that incorporates terms for through bed flow simulation of time varying seepage force and bed stress effects over an uprush backwash cycle suggests that the effect of altered bed stresses dominates over the change in effective weight and that infiltration exfiltration effects are most important during uprush simulated transport rates are increased by up to 40 of the peak transport rate during uprush and reduced by 10 during backrush in summary swash infiltration exfiltration across a saturated beach face enhances the net upslope transport of sediment

corroborated rainfall records from aragonitic stalagmites abstract sr and ba levels of two proximal aragonite speleothems from cold air cave south africa are examined at m resolution a compositional map derived from parallel secondary ion mass spectrometry linescans indicates heterogeneity perpendicular to the stalagmite growth axis precluding the use of single linescans as a climatic proxy technique a 40 yr averaged trace element record for the cave produced from multiple parallel linescans on both stalagmites is compared with regional and local climatic rainfall temperature data for 1955 1996 this period includes two extensive drought episodes there is poor correlation between trace elements and annual mean temperature droughts correspond to minima in trace element ratios and peaks correspond to annual maxima in rainfall the onset and termination of droughts are notable inflexions however in detail annual rainfall magnitude does not correlate directly with trace element ratios indicating that kinetic factors notably variations in speleothem growth rate play a key role in trace element uptake by aragonite averaged long data sets constrained by chronological control have potential in the study of sub decadal precipitation patterns

net sediment transport and morphological change in the swash zone of a high energy sandy beach from swash event to tidal cycle time scales abstract a field experiment was conducted on a high energy sandy beach truc vert france to examine swash zone processes and shoreline erosion accretion in response to changing wave and tide conditions beachface morphological changes were measured at the swash by swash timescale using an array of ultrasonic bed level sensors and at the tidal timescale through total station surveys hydrodynamic and sediment dynamic data were collected using arrays of pressure transducers electromagnetic current meters optical backscatter sensors and total load sediment traps data were collected for 16 consecutive days 33 tides over a spring neap spring tidal cycle with offshore significant wave heights of 1 4 m and periods of 5 12 s the swash motion was predominantly at infragravity wave frequencies over the measurement period the upper beach experienced phases of accretion erosion and stability trapped sediment loads for the uprush and backwash were predicted reasonably well by cross shore velocity skewness but the prediction of net transport over individual swash events by velocity based models was more problematic particularly lower in the swash zone where swash interactions were more prevalent net sediment fluxes over individual swash events often exceeded 100 kg per unit meter beach width and such rates were only one order of magnitude less than the net transport typically experienced across the high tide swash zone over complete tidal cycles upper beach erosion accretion at the tidal timescale was reasonably well predicted by the dean criterion based on offshore wave steepness and dimensionless fall velocity but the beach gradient also played a significant role in controlling the occurrence of erosion and accretion

beach cusp morphodynamics detailed measurements of three dimensional beach cusp morphology were made on a steep gradient low energy microtidal beach in perth western australia during the field campaign a variety of wave conditions and tidal ranges were experienced and these differing hydrodynamic conditions were reflected in a consistent pattern of morphological changes to the beach cusp system a useful parameter to delineate between trends of cusp destruction and re formation appeared to be the surf similarity parameter tan i0 l0 where h0 is offshore wave height l0 is deep water wave length and tan is beach gradient for 1 2 a small storm was experienced at the start of the field campaign period and resulted in considerable erosion of the beach face the cusp morphology across the lower beachface was destroyed but a subtle remnant of the pre storm cusp morphology was preserved on the upper beachface when cusps reformed after the storm under the influence of declining wave conditions they appeared at the same location and with the same dimensions as the pre storm cusp morphology hence it is considered that the cusp re formation was controlled more by the antecedent morphology than the hydrodynamic conditions this indicates that positive feedback between swash hydrodynamics and beachface morphology necessary to form beach cusps does not require a large variation in relief 1997 john wiley sons ltd

the 2002 2003 el nino recorded in australian cave drip waters implications for reconstructing rainfall histories using stalagmites 1 a 30 month study of drip hydrochemistry from kooringa cave eastern australia revealed a clear geochemical response to the 2002 2003 el nino through the drought drip discharge fell to base flow drip ca2 concentrations fell by half and drip mg ca and sr ca increased in a co varying pattern calcite mg ca and sr ca predicted from drip waters displayed a marked increase through and just beyond the period of greatest moisture deficit the results suggest that stalagmites from shallow caves in drought sensitive eastern australia potentially preserve a valuable record of el nino la nina history

seasonal variations in sr mg and p in modern speleothems grotta di ernesto italy sub annual variations in trace element chemistry and luminescence have recently been demonstrated from speleothems and offer the potential of high resolution palaeoclimatic proxies however no studies have yet examined microscopic trace element variations in relation to modern cave conditions in this study the spatial variations in trace element sr mg and p concentrations in speleothems a stalagmite and a soda straw stalactite from the alpine ernesto cave temperature 6 6 0 1 c in a forested catchment in ne italy have been studied using secondary ion mass spectrometry sims and compared with environmental parameters and waters in the modern cave an annual lamination exists in the stalagmite and soda straw stalactite in the form of clear calcite with narrow visible layers which are uv fluorescent and interpreted to contain soil derived humic fulvic acids washed into the cave during autumn rains microanalyses were undertaken of seven annual laminae probably deposited during the 1960s in the stalagmite and seven laminae in the 1990s for the stalactite the analysis results show that sr consistently has a trough and p a peak centred on the inclusion rich layer mg shows mainly a negative covariation with sr in laminae formed in the 1990s but a positive covariation in the stalagmite formed in 1960s the spatial scale of the main geochemical variations is the same as that of annual laminae of inclusion poor and inclusion rich couplets mass balance arguments are used to show that the p is inorganic in form and presumably occurs as individual phosphate ions within the calcite most drip waters show limited chemical variations but a summer peak in trace elements in 1995 and a decrease in mg ca in the following winter are notable more pronounced covariations in mg ca and sr ca are shown by a site with highly variable drip rates where ratios increase at slow drip rates the strongest seasonal variations are found in pool waters where ratios increase reflecting significant ca removal from the water into the calcite during the winter in response to seasonal pco2 variations in cave air thus the cave waters compositions tend to reflect climate conditions such that mg ca and sr ca are tentatively interpreted to be higher when climate conditions are dry combining results from the speleothems and cave water along with the behaviour of each trace species mg ca variations in the speleothems are considered to reflect their variation in the cave waters whereas sr incorporation is also dependent on precipitation rate in this case mainly controlled by temporal variations in pco2 in the cave and conceivably also by inhibitors such as phosphate p adsorption a fraction of which is subsequently incorporated within calcite depends on aqueous phosphate concentration and water flux both of which should increase during the autumn therefore multiple trace element profiles in speleothems reflect multiple aspects of environment seasonality and conditions and hence a calibration against weather records is desirable to establish their palaeoclimatological meaning the strong annual variation of trace elements and particularly p can provide chronological markers for high resolution studies of other climate proxies such as stable isotopes

trace element variations in coeval holocene speleothems from gb cave southwest england we report trace element mg sr and ba records based on laser ablation inductively coupled plasma mass spectrometry la icp ms from three coeval holocene speleothems from great chamber in gb cave southwest england the trace element records are placed on a common timescale on the basis of a suite of tims 230th 234u ages this permits assessment of the reproducibility of the trace element record in coeval speleothems the trace element records are not coherent raising dobuts over the reliability of individual trace element records as potential archives of palaeoenvironmental information mg sr in speleothem calcite has been proposed as a potential palaeothermometer as mg partitioning into calcite from water is temperaturedependent while sr partitioning into calcite is temperature independent however we present the results of calculations which demonstrate that the observed mg sr values in the three stalagmites cannot have been produced by holocene temperature changes alone and that other processes m

alongshore fluid motions in the swash zone of a sandy and gravel beach abstract field experiments were conducted on a low gradient high energy sandy beach truc vert france and a steep low energy gravel beach slapton uk to examine alongshore directed currents within the swash zone at truc vert data were collected over 33 tidal cycles with offshore significant wave heights of 1 4 m and periods of 5 12 s at slapton data were collected during 12 tides with wave heights of 0 3 1 m and periods of 4 9 s the swash motion was predominantly at infragravity frequencies at truc vert and incident frequencies at slapton during selected tides strong alongshore currents of the same order of magnitude as the cross shore flows were a consistent feature of both swash zones however while the cross shore flows were saw toothed with a distinct flow reversal the alongshore flows were unidirectional and continuous on the sand beach alongshore momentum was advected into the swash from the surf zone by standing long wave motion resulting in the strongest flows in the lower swash in contrast on the gravel beach highly oblique uprush directly forced the longshore directed motions and resulted in strong flow velocities in the upper swash on the sandy beach the cross and longshore boundary layers were consistently different with strong vertical shear during the uprush for the cross shore and during the backwash for the alongshore flows a logarithmic profile better fitted the longshore flows during the backwash compared to during the uprush for the cross shore flows and enabled the drag coefficient to be computed the alongshore drag coefficient was cd v 10 3 and of the same order as for the cross shore but was generally larger during the backwash compared to the uprush sediment transport efficiency during the backwash is potentially enhanced by longshore directed swash flows significant bed shear stress is maintained throughout that cross shore flow reversal enabling down slope transport earlier in the swash cycle

a multiple cave deposit assessment of suitability of speleothem isotopes for reconstructing palaeo vegetation and palaeo temperature the suitability of speleothems for interpreting palaeoclimate is typically determined by using either the hendy test overlapping analysis or long term cave environment monitoring however in many cases these methods are not applicable because a speleothem lacks clearly traceable layers for the hendy test it is difficult to obtain an overlapping speleothem nearby or long term cave monitoring is impractical the authors propose a multiple cave deposit approach to assess the suitability of speleothems for palaeoclimate study speleothems collected from two sites within raccoon mountain cave tennessee usa exhibit remarkable spatial variation 13c 10 3 to 2 2 over a relatively short distance ca 260 m drip water 18o values exhibit a seasonal precipitation signal at site 1 and an annual signal at site 2 combining field observations water isotope analysis and trace element data the authors propose that the speleothem formation at site 1 and site 2 tapped distinct sources of co2 i co2 derived from overlying soils for site 1 and ii limestone dissolved inorganic carbon induced by ground water dissolution for site 2 using fresh cave deposits modern speleothem 13c 100 c3 vegetation as an analogue a simple model was developed to estimate land surface vegetation for speleothems the speleothem formation temperature estimated using fresh cave deposit 18o values generally reflects the mean annual temperature in this region this study indicates that spatial variations in carbon isotopes could be caused by different carbon sources dominating in different parts of the cave which should be taken into consideration by researchers when using speleothem 13c values to reconstruct temporal palaeo vegetation changes this study demonstrates a practical sampling strategy for verifying suitability of speleothems for palaeo vegetation and palaeo temperature reconstructions by analysing multiple cave deposits especially for cases in which the hendy test parallel sampling and long term monitoring of cave environment are not feasible

trace elements in speleothems as recorders of environmental change speleothems are now established as important palaeoenvironmental archives and contain a number of suitable proxies although trace elements have been much less widely used than oxygen and carbon isotopes the complexity of the cave environment helps to explain this since the fluids from which speleothems form vary greatly in composition in space even within a cave chamber seasonally and over longer periods understanding the forcing factors for this variability is the key to decoding the significance of the trace element records a variety of techniques are available for trace element work and it is important to understand the strengths and limitations of each and also to seek an understanding e g by micro imaging techniques of whether the elements are associated with inclusions in the caco3 or are isolated within the crystal lattice for some elements there is a more or less predictable relationship between element ratios to ca in the water and in the calcite individual trace elements may be derived from atmospheric deposition superficial deposits or bedrock and can be recycled in soil processes before being transferred to the cave some components show an instantaneous response to water infiltration whereas others are only leached by slow flowing seepage waters changing in the proportion of water from fracture fed and seepage flow aquifer compartments is an important factor in influencing trace element supply high flows lead to higher fluxes of soil derived colloidally transported elements conversely under relatively dry conditions degassing of co2 results in prior calcite precipitation upflow of the site of speleothem deposition and leads to higher ratios of sr ca and mg ca some trace element variations in speleothems over time are induced during crystal growth whereby faster growth leads to a greater departure from equilibrium element partitioning despite the demonstrated temperature dependence of mg partitioning into calcite attempts at deriving palaeotemperature records from speleothems have been so far confounded by variations in solution mg ca and or crystallographic effects a number of case studies have effectively used trace elements such as speleothem mg as records of palaeo aridity using supporting arguments from modern monitoring or covariations with other parameters such as stable isotopes sr and u isotopes can also be indicators of palaeohydrology although sr isotope variations can also reflect varying aeolian input considerable progress has been made in decoding the meaning of annual trace element variations using criteria for understanding dripwater hydrology and ph this should lead in the future to more specific interpretations of how seasonality evolves through time

recent advances in modeling swash zone dynamics influence of surf swash interaction on nearshore hydrodynamics and morphodynamics the role of the swash zone in influencing the whole nearshore dynamics is reviewed with a focus on the interaction between surf and swash zone processes local and global hydromorphodynamic phenomena are discussed in detail and a description of the overall swash zone operation is given the effects of swash zone boundary conditions are highlighted together with the importance of surf zone boundary conditions major emphasis is placed on illustrating the interactions of various hydrodynamic modes which in turn control the swash and surf zone morphology finally methods to account for swash zone processes in coastal models with different temporal and spatial resolutions are proposed

holocene climate variability in europe evidence from δ18o textural and extension rate variations in three speleothems time series o isotope profiles for three u th dated stalagmites have revealed that for much of the holocene a site on the atlantic seaboard sw ireland exhibits first order 18o trends that are almost exactly out of phase with coupled 18o curves from two southern european sites se france and nw italy in the irish stalagmite cc3 from crag cave sw ireland low 18o at 10 000 cal yr bp reflects cool conditions by the early to mid holocene 9000 6000 cal yr bp 18o had increased reflecting the onset of warmer conditions on the atlantic seaboard this shift to higher 18o was accompanied by a marked increase in the stalagmite extension rate reinforcing our interpretation that this was a period of relative warmth except for an episode of increased extension rate about 5500 yr ago 18o in the crag stalagmite exhibits a gradual decrease accompanied by declining extension rates between 7800 and 3500 cal yr bp interpreted as a cooling trend there is evidence for increases in both 18o and stalagmite extension rate in the period from 3500 cal yr bp to the present day suggesting a return to warmer conditions on the atlantic seaboard in the stalagmite from nw italy er76 grotta di ernesto trentino province the early holocene c 9200 7800 cal yr bp is characterised by high 18o probably indicative of warm and or dry conditions exceptionally low 18o from 7800 to 6900 cal yr bp at this site reflects a well defined wet phase cerin wet phase in the last three millennia this stalagmite exhibits a shift to lower 18o interpreted as some combination of cooler and or wetter conditions unlike the irish stalagmite the italian sample does not show a correlation between 18o and extension rate instead its extension rate correlates roughly with 13c presumably reflecting a climate driven vegetation change in the early holocene 18o in the french stalagmite cl26 grotte de clamouse herault province se france was low relative to its holocene average for much of the period since c 3500 cal yr bp this stalagmite exhibits higher 18o than in the early holocene suggesting warmer conditions like the irish stalagmite the french sample exhibits a well defined correlation between 18o and extension rate had drip water availability been the dominant control on 18o at this semi arid site then higher 18o would have been accompanied by lower not higher extension rates this suggests strongly that temperature rather than rainfall amount was the dominant control at this site while conclusions regarding the patterns of climate variability on a continent scale must remain tentative because of the limited number of stalagmites studied we argue that early holocene warm conditions on the atlantic seaboard irish site coincided with relatively cool conditions at the clamouse site by c 3500 yr ago the pattern appears to have been reversed

origin and palaeoenvironmental significance of lamination in stalagmites from katerloch cave austria the origin and environmental dependencies of lamination in stalagmites from katerloch common in speleothems from other cave sites are examined in detail petrographic observations and chemical analyses including isotopes of stalagmites and modern calcite were combined with multi annual cave monitoring all investigated stalagmites are composed of low mg calcite and show white porous laminae and typically thinner translucent dense laminae the binary lamination pattern results from changes in the calcite fabric white porous laminae are characterized by a high porosity and abundant fluid inclusions and also by enhanced vertical growth and thinning towards the flanks translucent dense laminae exhibit a compact fabric and constant thickness of individual growth layers u th dating supports an annual origin of the lamination and the seasonally changing intensity of cave ventilation provides a robust explanation for the observed relationships between lamination stable c isotopic compositions and trace elements mg sr and ba the seasonally variable air exchange driven by temperature contrasts between the cave interior and outside atmosphere modulates the rate and amount of co2 degassing from the drip water and affects the hydrochemistry and consequently the fabric of the precipitating calcite although cave air composition and drip rate are both major variables in controlling co2 degassing from the drip water the seasonally changing ventilation in katerloch exerts the primary control and the results suggest a secondary amplifying attenuating influence of the drip rate drip rate however might be the controlling parameter for lamina development at cave sites experiencing only small seasonal cave air exchange importantly the seasonally variable composition of drip water does not reflect the seasonal cycle of processes in the soil zone but results from exchange with the cave atmosphere the alternating porous and dense calcite fabric is the expression of a variable degree of lateral coalescence of smaller crystallites forming large columnar crystals the white porous laminae represent partial coalescence and form during the warm season low calcite 13c values are linked to low 13c values of cave air and drip water during that time this observation corresponds to times of reduced cave ventilation high pco2 of cave air low drip water ph lower calcite supersaturation and typically high drip rates in contrast the translucent dense laminae represent more or less complete lateral coalescence inclusion free during the cold season high calcite drip water and cave air 13c values i e times of enhanced cave ventilation low cave air pco2 increased drip water ph relatively high calcite supersaturation and typically low drip rates in essence the relative development of the two lamina types reflects changes in the seasonality of external air temperature and precipitation with a strong control of the winter air temperature on the intensity of cave air exchange thick translucent dense laminae are favoured by long cold and wet winters and such conditions may be related closely to the north atlantic oscillation mode weak westerlies and enhanced mediterranean cyclone activity during the cold season studies of speleothem lamination can thus help to better understand and quantify the role of seasonality changes for example during rapid climate events

oxygen and hydrogen isotopes of rainfall and dripwater at desoto caverns alabama usa key to understanding past variability of moisture transport from the gulf of mexico abstract the southeast and the us gulf coast in particular are notably lacking isotope data in the water cycle despite the fact that moisture transport from the gulf of mexico gom has a considerable influence on both regional and continental rainfall patterns this study reports time series of oxygen and hydrogen isotopes acquired over a 3 year period 2005 2008 from gom derived rainfall cave dripwater and shallow groundwaters and offers valuable insights on the links between factors controlling regional rainfall and the ubiquitous karst hydrology amount weighted mean monthly rainwater 18o and d values in tuscaloosa alabama range from 1 5 to 8 3 and 1 2 to 49 5 respectively and show mean seasonal amplitudes of 4 18o and 25 d in comparison d excess values display large seasonal amplitudes of 10 20 resulting from differences in the degree of evaporation from falling raindrops between summer and winter months and correlate well with the coeval air temperature r2 0 59 p dripwater samples from nearby desoto caverns show weak 18o and d seasonal variations and record only 20 and 51 of the 18o and 2h enrichments respectively discerned in the rainwater 3 year time trends the seasonal and interannual amplitude attenuations in the dripwaters are attributed to a relatively thick overlying bedrock 30 40 m and a relatively large well mixed epikarst storage reservoir residence time of water in the cave s epikarst is estimated to be 1 3 months based on high resolution flow rate data our investigation suggests that global atmospheric circulation patterns enso and bermuda high likely govern the interannual 18o and d isotope trends discerned in the water cycle compartments but much longer time series are required to confirm our conjectures the results of this study form a solid basis for future acquisition and interpretation of climate proxy records from regional speleothems

swash zone sediment fluxes field observations abstract this paper describes newly obtained high frequency observations of beach face morphological change over numerous tidal cycles on a macrotidal sandy beach made using a large array of ultrasonic altimeters these measurements enable the net cross shore sediment fluxes associated with many thousands of individual swash events to be quantified it is revealed that regardless of the direction of net morphological change on a tidal time scale measured net fluxes per event are essentially normally distributed with nearly equal numbers of onshore and offshore directed events the majority of swash events cause net cross shore sediment fluxes smaller than 50 kg m 1 and the mean sediment flux per swash event is only o 1 kg m 1 leading to limited overall morphological change however much larger events which deposit or remove hundreds of kilograms of sand per meter width of beach occur at irregular intervals throughout the course of a tide it was found that swash swash interactions tend to increase the transport potential of a swash event and the majority of the swash events that cause these larger values of sediment flux include one or more interactions the majority of the larger sediment fluxes were therefore measured in the lower swash zone close to the surf swash boundary where swash swash interactions are most common despite the existence of individual swash events that can cause fluxes of sediment that are comparable to those observed on a tidal time scale frequent reversals in transport direction act to limit net transport such that the beach face volume remains in a state of dynamic equilibrium and does not rapidly erode or accrete

hydrogeochemical and climatic interpretations of isotopic signals from precipitation to drip waters in liangfeng cave guizhou province china oxygen isotope is a commonly used proxy for paleoclimatic studies on stalagmites in order to understand the transmission of isotopic signals from precipitation to stalagmites meteorological indexes of exterior and interior cave and hydrogeochemical proxies of drip waters in liangfeng cave have been monitored from april 2011 to april 2013 samples of rain and drip waters from three drip sites designated as 1 5 and 6 are collected for hydrogen and oxygen isotopes testing results show that the amount weighted mean 18o value of rain in the first year may 9 2011 to may 1 2012 is lighter than that in the second may 30 2012 to may 2 2013 this may result from different proportions of the pacific indian ocean source moistures the arithmetic mean 18o values of 1 5 and 6 are similar to the multi year amount weighted mean 18o value of precipitation hydrogeochemical analyses of drip waters reveal that the discharge rates increase in the order of 6 1 5 and that water rock reaction fresh old water mixing and co2 degassing exert dominant controls on seepage waters in aquifers hard infiltration of rain during dry season with heavier 18o value due to its small amount may cause lower mean drip water 18o values e g 1 evaporation during the dripping and exuding processes in dry season may result in heavier mean drip water 18o values e g 6 considering calcite depositing mostly during dry season we compare the mean 18o values of drip waters during dry season between the first and second years differences exist and share the same trend with rain the results indicate that drip waters can inherit oxygen isotopic signals of rain but it is critical to have a replication test on 18o records of stalagmites from the same cave for paleoclimatic studies what s more 18o values in stalagmites feeding by drip waters that have no little annual 18o variations may be useful to paleotemperature reconstructions

controls on trace element sr mg compositions of carbonate cave waters implications for speleothem climatic records abstract at two caves clamouse s france and ernesto ne italy cave drip and pool waters were collected and sampled at intervals over a 2 3 year period mg ca and sr ca concentration ratios corrected for marine aerosols are compared with those of bedrocks and in some cases aqueous leachates of soils and weathered bedrocks cave waters do not lie along mixing lines between calcite and dolomite of bedrock carbonate but typically show enhanced and covarying mg ca and sr ca four factors are considered as controlling processes 1 the much faster dissolution rate of calcite than dolomite allows for the possibility of increase of mg ca if water rock contact times are increased during drier conditions a theoretical model is shown to be comparable to experimental leachates 2 prior calcite precipitation along a flow path is a powerful mechanism for generating enhanced and covarying mg ca and sr ca ratios this mechanism requires the solution to lose co 2 into pores or caverns 3 incongruent dolomite dissolution has only limited potential and is best regarded as two separate processes of dolomite dissolution and calcite precipitation 4 selective leaching of mg and sr with respect to ca is shown to be important in leachates from ernesto where it appears to be a phenomenon of calcite dissolution in general selective leaching can occur whenever ca is sequestered into precipitates due to freezing or drying of soils or if there is derivation of excess sr and mg from non carbonate species the ernesto cave has abundant water supply which in the main chamber is derived from a reservoir with year round constant p co 2 of around 10 2 4 and no evidence of calcite precipitation in the karst above the cave two distinct but overlying trends of enhanced and covarying mg ca and sr ca away from the locus of bedrock compositions are due to calcite precipitation within the cave and at a variable drip site due to enhanced selective leaching at slow drip rates mg enhancement in the first chamber is due to a more dolomitic bedrock and longer residence times the clamouse site has a less abundant water supply and presents geochemical evidence of prior calcite precipitation both in the cave and in overlying porous dolomite dedolomitized limestone bedrock initial p co 2 values as high as 10 1 are inferred experimental incubations of clamouse soils which generated enhanced p co 2 and precipitated caco 3 had compositions similar to the karst waters calcite precipitation is inferred to be enhanced in drier conditions hydrological controls on cave water chemistry imply that the trace element chemistry of speleothems may be interpretable in palaeohydrological terms drier conditions tends to promote not only longer mean residence times enhancing dolomite dissolution and hence mg ca but also enhances degassing and calcite precipitation leading to increased mg ca and sr ca

pile load tests in saline permafrost at clyde river northwest territories significant salt content in the pore phase of permafrost causes dramatic reduction in strength or bearing capacity previous experience with laboratory tests and limited field testing discussed in the soviet literature indicate that creep rates can be accelerated many times and foundation bearing capacities reduced by factors of 2 3 if pore water salinities exceed 10 20 ppt at clyde river on the northwest coast of baffin island pile load tests were carried out in 1982 a combination of high salinities and significant excess ice contents at some locations suggested that a limited program of pile load testing should be carried out to confirm or modify the initial pile loadings based on previously published material no fully documented case history was available to support initial pile design loads three piles were subjected to loads of five different magnitudes for different durations creep settlement was initiated and persisted in all cases continuous curve fitting was carried out by computer and the

measurement of wave by wave bed levels in the swash zone abstract a technique is described to observe and quantify wave by wave bed level changes in the swash zone the ultrasonic instrument system is non contact with the beach face surface being measured and the sensors remain outside of the fluid flows causing sediment movement sensor resolution combined with the electronic noise inherent within a digital network data logging system results in a conservative measurement accuracy of 1 mm equating to a couple of sand grain diameters in height illustrative field results demonstrate the practical use of the instrumentation and a simple data pre processing method to separate swashes and intervening bed level events is discussed these example data reveal rather complex fluctuations of the bed observed over time periods of minutes to hours rather strikingly gross bed level changes per wave are revealed to be up to many orders of magnitude larger than the observed net rate of beach face evolution it is outlined how observations of successive bed level changes at multiple locations within a dense grid combined with a consideration of sediment continuity will now enable the total net sediment transported per uprush backwash to be quantified

the deep permafrost carbon pool of the yedoma region in siberia and alaska estimates for circumpolar permafrost organic carbon oc storage suggest that this pool contains twice the amount of current atmospheric carbon the yedoma region sequestered substantial quantities of oc and is unique because its deep oc was incorporated into permafrost during ice age conditions rapid inclusion of labile organic matter into permafrost halted decomposition and resulted in a deep long term sink we show that the deep frozen oc in the yedoma region consists of two distinct major sub reservoirs yedoma deposits late pleistocene ice and organic rich silty sediments and deposits formed in thaw lake basins generalized as thermokarst deposits we quantified the oc pool based on field data and extrapolation using geospatial datasets to 83 61 57 gt for yedoma deposits and to 128 99 96 gt for thermokarst deposits the total yedoma region 211 160 153 gt is a substantial amount of thaw vulnerable oc that must be accounted for in global models

discussion of measurement of wave by wave bed levels in the swash zone by ian l turner paul e russell tony butt coastal eng 55 2008 1237 1242 this paper is a discussion of turner et al measurement of wave by wave bed levels in the swash zone the discussion highlights previous work on the same topic that in fact demonstrated swash by swash measurements of total net sediment transport but which was not presented by turner et al the discussion highlights the advantages and disadvantages of the two measurement methods and the problem of longshore sediment motion which can introduce errors c 2008 elsevier b v all rights reserved

characteristics of cryogenic soils along a latitudinal transect in arctic alaska the morphological chemical and physical properties of arctic tundra soils were examined along a 200 km latitudinal gradient in northern alaska which includes two major physiographic provinces the arctic coastal plain and the arctic foothills annual air temperature and precipitation increase along the gradient from north to south soils on the arctic coastal plain support wet nonacidic tundra vegetation and have high carbonate contents soil on the arctic foothills support moist nonacidic tundra in the northern part and moist acidic tundra in the southern part most arctic tundra soils are characterized by medium texture poor drainage and high organic matter content from north to south along the transect the base saturation of the active layer decreases and exchangeable aluminum increases from north to south most soils have strongly developed cryogenic features including warped and broken horizons ice lenses thin platy structure and organic matter frost churned into the ice rich upper permafrost horizons

rapid water table fluctuations within the beach face implications for swash zone sediment mobility abstract to incorporate groundwater infiltration exfiltration in the description of swash zone sediment transport it is required that the details of groundwater dynamics within the beach face be clarified field measurements of the vertical pore pressure structure within the bed identify capillarity effects as the primary mechanism driving rapid and relatively large magnitude water table fluctuations within the swash zone when the upper extent of the fully saturated capillary fringe coincides with the beach face surface wave runup produces near instantaneous increase in pore pressures across the capillary fringe corresponding to a rapid rise of the phreatic surface i e the surface where pore pressure atmospheric pressure to the sand surface therefore counter to previous conclusions in the literature the rapid rise and fall of the water table under the swash zone do not equate to regions of the beach face alternating between states that favor sediment deposition unsaturated and erosion saturated similar reports that rapid fluctuations of the water table within the beach face correspond to rapid rates of vertical flow and hence bed fluidization are also a misinterpretation field measurements and a careful consideration of saturation and pore pressure characteristics within the beach face demonstrate that rapid water table rise is associated with minute downwards swash infiltration rather than rapid upwards groundwater exfiltration the cause of the pressure fluctuations and phreatic surface oscillations is the alternating appearance and disappearance of meniscuses at the sand surface which generate pressure head fluctuations of decimeters due to the addition of millimeters of water

late quaternary ice rich permafrost sequences as a paleoenvironmental archive for the laptev sea region in northern siberia ice rich permafrost sequences with large polygonal ice wedges represent excellent archives for paleoenvironmental reconstruction such deposits contain numerous well preserved records ground ice paleosols peat beds different types of fossils which permit characterization of environmental conditions during a clearly defined period of the past 60 ka based on field investigations carried out within framework of the german russian project laptev sea system 2000 on the bykovsky peninsula se of the lena delta results from cryolithological studies sedimentological analyses as well as new radiocarbon data are presented for the first time it is shown that the ice complex accumulated without significant interruptions from approximately 60 k y b p until the end of the pleistocene geochemical data total organic carbon c n 13corg and the mass specific magnetic susceptibility clearly show changing environmental conditions from stadial to interstadial times in the late pleistocene and during the transition to the holocene these results permit us to reconstruct the development of an arctic periglacial landscape in the coastal lowland during ice complex formation in the late quaternary this evolution coincided generally with the global environmental trend up to marine isotope stage 4

pan arctic ice wedge degradation in warming permafrost and its influence on tundra hydrology ice wedges are common features of the subsurface in permafrost regions they develop by repeated frost cracking and ice vein growth over hundreds to thousands of years ice wedge formation causes the archetypal polygonal patterns seen in tundra across the arctic landscape here we use field and remote sensing observations to document polygon succession due to ice wedge degradation and trough development in ten arctic localities over sub decadal timescales initial thaw drains polygon centres and forms disconnected troughs that hold isolated ponds continued ice wedge melting leads to increased trough connectivity and an overall draining of the landscape we find that melting at the tops of ice wedges over recent decades and subsequent decimetre scale ground subsidence is a widespread arctic phenomenon although permafrost temperatures have been increasing gradually we find that ice wedge degradation is occurring on sub decadal timescales our hydrological model simulations show that advanced ice wedge degradation can significantly alter the water balance of lowland tundra by reducing inundation and increasing runoff in particular due to changes in snow distribution as troughs form we predict that ice wedge degradation and the hydrological changes associated with the resulting differential ground subsidence will expand and amplify in rapidly warming permafrost regions the polygonal patterns in permafrost regions are caused by the formation of ice wedges observations of polygon evolution reveal that rapid ice wedge melting has occurred across the arctic since 1950 altering tundra hydrology

sensitivity of bunker cave to climatic forcings highlighted through multi annual monitoring of rain soil and dripwaters abstract the last two decades have seen a considerable increase in studies using speleothems as archives of past climate variability caves under study are now monitored for a wide range of environmental parameters and results placed in context with speleothem data the present study investigates trends from a seven year long monitoring of bunker cave northwestern germany in order to assess the hydraulic response and transfer time of meteoric water from the surface to the cave rain soil and dripwater were collected from august 2006 to august 2013 at a monthly to bimonthly resolution and their oxygen and hydrogen isotope composition was measured furthermore drip rates were quantified due to different drip characteristics annual mean values were calculated for the drip rates of each drip site correlations of the annual mean drip rate of each site with precipitation and infiltration demonstrate that the annual infiltration and thus the annual precipitation control the inter annual drip rate variability for all except one site the hydraulic response is not delayed on an annual basis all drip sites display identical long term trends which suggests a draining of a common karst reservoir over these seven years of monitoring correlations of soil and dripwater monthly 18o and d values with atmospheric temperature data reveal water transfer times of 3 months to reach a depth of 40 cm soilwater at site bw 2 and 4 months for 70 cm depth soilwater at site bw 1 finally the water reaches the cave chambers 15 to 30 m below land surface after ca 2 5 years consequently a temporal offset of 29 to 31 months ca 2 5 years between the hydraulic response time no time lag on annual basis and the water transfer time time lag of 29 to 31 months was found which is negligible with regard to bunker cave speleothems because of their slow growth rates here proxies recording precipitation infiltration and temperature are registered on a decadal scale variations in drip rate and thus precipitation and infiltration are recorded by 13c and mg ca ratios in speleothem calcite speleothem 18o values reflect both temperature and precipitation signals due to drip rate related fractionation processes we document that long term patterns in temperature and precipitation are recorded in dripwater patterns of bunker cave and that these are linked to the north atlantic oscillation nao

soil organic carbon pools in the northern circumpolar permafrost region of all soils in the northern permafrost region is approximately 18 782 10 3 km 2 o r approximately 16 of the global soil area in the northern permafrost region organic soils peatlands and cryoturbated permafrost affected mineral soils have the highest mean soil organic carbon contents 32 2 69 6 kg m 2 here we report a new estimate of the carbon pools in soils of the northern permafrost region including deeper layers and pools not accounted for in previous analyses carbon pools were estimated to be 191 29 pg for the 0 30 cm depth 495 80 pg for the 0 100 cm depth and 1024 00 pg for the 0 300 cm depth our estimate for the first meter of soil alone is about double that reported for this region in previous analyses carbon pools in layers deeper than 300 cm were estimated to be 407 pg in yedoma deposits and 241 pg in deltaic deposits in total the northern permafrost region contains approximately 1672 pg of organic carbon of which approximately 1466 pg or 88 occurs in perennially frozen soils and deposits this 1672 pg of organic carbon would account for approximately 50 of the estimated global belowground organic carbon pool

swash zone sediment transport step dynamics and morphological response on a gravel beach abstract state of the art morphodynamic field data were collected from slapton sands uk a fine gravel beach d50 2 10 mm over a 10 day period under a range of wave tide conditions comprising a mixture of southerly swell and easterly wind waves hs 0 5 1 m ts 4 8 s tide range 3 4 m over the field period the upper beach experienced accretion and berm formation during tides with low steepness swell dominated wave conditions h l 0 01 surprisingly the intertidal beach showed an opposite trend with sediment losses under swell conditions and an increase in sediment volume due to wind waves and suggests that upper beach morphological change can be decoupled from the overall sediment budget a submerged accretionary feature the beach step grew and migrated onshore on the rising tide typically reaching a maximum relief of around 0 5 m then gradually decreased in prominence while migrating offshore as the tide fell resulting in little net morphological change the step was better developed during the falling tide than the rising tide and through its control on the swash hydro and sediment dynamics the step had a significant effect on the development of the berm swash flow velocities under the conditions measured were often in excess of 2 m s 1 for both the uprush and the backwash onshore mean flows occurred in the upper swash region 40 inundation was characterised by offshore mean flows swash infiltration losses in the swash zone increased from 40 in the lower swash region to 100 in the upper swash region the most energetic swash flows and the strongest offshore mean flows occurred at the transition between swash zone and surf zone 90 100 inundation

quaternary deposits and glacial stratigraphy in ireland quaternary stratigraphic studies in ireland have been based largely on lithostratigraphy the division of complex sedimentary sequences into the traditional framework of munsterian and midlandian events has created a series of stratigraphic scenarios which cannot be fully substantiated either by biostratigraphy or by facies basin analysis many of the current problems of glacial stratigraphy in ireland therefore arise directly from the field procedures used and the frameworks used to subdivide sedimentary sequences these problems are centred on the selection of type sites the subdivision of sedimentary sequences into unnatural divisions the concepts of direct and indirect stratigraphy classical models of climatically determined ice advance retreat cycles and the genetic inferences of the term till the conceptual basis of various stratigraphic schemes has changed little since the work of farrington 1934 1966 it is argued that a more realistic approach to description and assessment of glacigenic sediments should be based on basinal facies analysis and must include a documentation of the composition and geometry of three dimensional facies variations palaeoenvironmental interpretations of complex glacigenic sequences especially in coastal locations should take account of the influences of marine ice sheets on the sedimentary record in the past most sequences were interpreted in terms of glacioterrestrial models a large body of sedimentary evidence now indicates that shallow glaciomarine environments occurred along the margins of the last ice sheet during its maximum and subsequent retreat phases the locations and patterns of associated icemarginal systems indicate that the magnitude of and patterns of crustal deformation were greater and more complex than formerly realised thus the primary control on sea level variation at successive ice sheet margins was largely a function of glacioisostatic disequilibrium although complex glacial and glacially related sequences are known it is argued here that most of the multiple glacigenic sequences in ireland can be accommodated within the midlandian cold stage the basal units from certain sequences and erratic fans have been attributed to events earlier than the midlandian however it is difficult to compare these traces of earlier events from different sectors of the island due to poor dating correlation and the fact that direct and indirect stratigraphy is not adequately defined or separated the age of the gortian style interglacial sequences the implications of their floristic composition and their relationships to drift stratigraphy remains a major problem in stratigraphic constructions of the irish quaternary the stratigraphic significance of many till units must remain largely unknown until these matters are resolved at present it is not clear if the gortian sequences represent more than one interglacial a series of exposures in ulster provide evidence for major environmental changes during the midlandian cold stage these include an early stadial an early forest biozone 48 1 ka bp an early herb biozone 41 5 ka bp a middle interstadial phase of cold but non glacial aspect 30 5 ka bp a late stadial max 24 22 ka bp and a late glacial climatic oscillation the late midlandian stadial comprises a major glaciation that almost covered the island and a later more restricted phase when drumlins formed in the northern and western parts of the island max 17 ka bp

microtopographic and depth controls on active layer chemistry in arctic polygonal ground polygonal ground is a signature characteristic of arctic lowlands and carbon release from permafrost thaw can alter feedbacks to arctic ecosystems and climate this study describes the first comprehensive spatial examination of active layer biogeochemistry that extends across high and low centered ice wedge polygons their features and with depth water chemistry measurements of 54 analytes were made on surface and active layer pore waters collected near barrow alaska usa significant differences were observed between high and low centered polygons suggesting that polygon types may be useful for landscape scale geochemical classification however differences were found for polygon features centers and troughs for analytes that were not significant for polygon type suggesting that finer scale features affect biogeochemistry differently from polygon types depth variations were also significant demonstrating important multidimensional aspects of polygonal ground biogeochemistry these results have major implications for understanding how polygonal ground ecosystems function and how they may respond to future change

soil and karst aquifer hydrological controls on the geochemical evolution of speleothem forming drip waters crag cave southwest ireland abstract in recent years there has been increased interest in cave speleothems as archives of palaeoclimate monitoring of rainfall and soil and karst water chemistries was performed at crag cave castleisland co kerry southwest ireland in august 1997 and january 1998 in order to understand temporal and spatial variations in karst water hydrology and chemistry and their implications for interpreting the potential palaeohydrological signal preserved by speleothems at this site temporal variations in karst water drip rates and geochemistry allow drips to be classified by hydrological response to rainfall and the associated processes of dilution piston flow source change and prior calcite precipitation during aquifer throughflow evolution from soil matrix and preferential flow solutions has also been determined to exert an important control on karst water chemistries as a result of these findings we present hydrogeochemical models and plumbing diagrams that delineate the controls on karst water evolution at a number of sampling locations within the cave at this site we propose that a palaeohydrological signal may be recorded by crag cave speleothems that may be interpreted via the study of mg ca ratios in speleothems linked to monitoring of modern drip water chemistry

measurements and modeling of swash induced pressure gradients in the surface layers of a sand beach field measurements of swash induced hydraulic pressure gradients in the surface layers of a sand beach are presented and compared to a one dimensional diffusion model the model provides a description of flow through a porous quasi saturated sediment and is driven by the time varying swash depth on the beach surface the field measurements broadly show four different types of pressure propagation behavior which appear dependent on cross shore position in the swash zone the hydraulic gradients within the surface layers of the beach are typically found to be much greater than those likely to be generated by tidally induced groundwater flow in these instances the diffusion model generally provides a good description of the data however very large hydraulic gradients are frequently observed just below the beach surface and these cannot be adequately described by the diffusion model a mechanism is proposed through which these large hydraulic gradients could be generated

spatial variability in cave drip water hydrochemistry implications for stalagmite paleoclimate records the identification of vadose zone hydrological pathways that most accurately transmit climate signals through karst aquifers to stalagmites is critical for accurately interpreting climate proxies contained within individual stalagmites a three year cave drip hydrochemical study across a spectrum of drip types in crag cave sw ireland reveals substantial variability in drip hydrochemical behaviour stalagmites fed by very slow drips 2 ml min sites apparently unconnected with local meteorological events water from these drips was typically undersaturated with respect to calcite and thus did not result in calcite deposition data presented here suggest that drips in this flow regime also experience flow re routing and blocking and that any stalagmites developed under such drips are unsuitable as mid to high resolution paleoclimate proxies most drip sites demonstrated seasonal ca2 and mg2 variability that was probably linked to water excess prior calcite precipitation along the flowpath affected the chemistry of slowly dripping sites while dilution predominantly controlled the water chemistry of the more rapidly dripping sites this research underscores the importance of understanding drip hydrology prior to selecting stalagmites for paleoclimate analysis and before interpreting any subsequent proxy data

measurements of the time varying free surface profile across the swash zone obtained using an industrial lidar the use of an industrial lidar instrument to measure time varying water surface elevations within the swash zone is investigated the propagation of the swash lens across the beach face was measured simultaneously by a lidar instrument and a network of precision ultrasonic altimeters at a sandy beach comparison of the two datasets indicates that the time varying swash free surface profile obtained using a lidar compare favourably with point measurements obtained using ultrasonic altimeters significantly the use of a continuously scanning laser beam enables a single lidar instrument to obtain measurements of free surface elevation near synchronously at several hundred points throughout the swash zone this high spatial resolution permits small scale flow features such as the swash front gradient and the presence of secondary bores to be detailed and negates the need for the deployment of a large multi sensor array

large scale laboratory investigation into the effect of varying back barrier lagoon water levels on gravel beach morphology and swash zone sediment transport abstract it is generally accepted that the effect on beach morphology of the interactions between swash motion and the beach groundwater table depends on the elevation of the latter relative to that of the sea specifically a low beach groundwater table is considered to enhance onshore sediment transport and beach accretion while the reverse is thought to hold for a high beach groundwater table here we use the results of a carefully designed series of tests conducted in the delta flume the netherlands as part of the barrier dynamics experiment bardex to unequivocally demonstrate the validity of this assertion during the experiment a 4 m high and 50 m long gravel barrier d 50 11 mm was constructed within the central region of the 250 m long and 7 m deep wave flume enabling a back barrier lagoon to be located at its landward side the groundwater table in the beach was manipulated by lowering and raising the lagoon level and the gravel beach was subjected to variable wave conditions and sea lagoon levels using as the initial beach profile the morphology resulting from 90 min of wave forcing with the sea and lagoon at the same level the identical wave forcing with a low lagoon level consistently resulted in onshore sediment transport in the swash zone and beach accretion whereas the identical wave forcing with a high lagoon level consistently caused offshore sediment transport in the swash zone and beach erosion the divergent beach morphological responses for the low and high lagoon levels could not be attributed to changes in the bulk swash hydrodynamics i e based on single point velocity measurements arising from a difference in the amount of swash infiltration into the unsaturated beach instead application of a sediment transport model that accounts for the effects of in exfiltration suggested that the onshore sediment transport and beach accretion for the low lagoon tests mainly resulted from enhanced bed shear stresses during the wave uprush due to infiltration into the saturated part of the beachface due to the large hydraulic conductivity of gravel k o 0 1 m s 1 the effect of altered shear stresses due to in exfiltration may be an important factor in sediment transport in the swash zone of gravel beaches

comparison of high resolution sub annual records of trace elements in a modern 1911 1992 speleothem with instrumental climate data from southwest australia high spatial resolution measurements of mg p u sr ba and na using 193 nm excimer laser ablation inductively coupled plasma mass spectrometry has revealed clearly resolvable annual cycles in a modern speleothem from southwestern australia the age of this stalagmite is established by the dates of emplacement and removal of the boardwalk where it grew 1911 1992 this chronological constraint allows for the first confident comparison between the instrumental climate record and speleothem trace element content eleven laser ablation transects across a 0 5 mm wide section of the speleothem growth axis were measured cycles that could be matched between adjacent transects were stacked into a master record to minimise variability between tracks and permit greater confidence in comparing the trace elements to the instrumental climate record p and u positively and mg inversely mimic the sudden 20 decrease in annual rainfall experienced by this region since 1965 we argue that p from seasonal vegetation decay is transported to the speleothem before it is mineralised in the soil owing to the low p retention capacity of southwest australian soils both vegetation activity and the transport of vegetation derived hpo42 are sensitive to rainfall groundwater p concentration may also influence the transport of u through the strong affinity between phosphate and uranyl ions mg appears to be sensitive to groundwater residence time as this affects drip water mg ca composition by preferential loss of ca during drier episodes when calcite precipitates before reaching the stalagmite the effects of groundwater residence time may also be important for sr on inter annual scales however the behaviour of sr on the annual cycle is opposite to mg but compatible with ba and na which are shown to depend on speleothem growth rate

an effective medium model for p wave velocities of saturated unconsolidated saline permafrost abstractto better understand the relationship between p wave velocities and ice content in saturated unconsolidated saline permafrost we constructed an effective medium model based upon ultrasonic p wave data that were obtained from earlier laboratory studies the model uses a two end member mixing approach in which an ice filled fully frozen end member and a water filled fully unfrozen end member are mixed together to form the effective medium of partially frozen sediments this mixing approach has two key advantages 1 it does not require parameter tuning of the mixing ratios and 2 it inherently assumes mixed pore scale distributions of ice that consist of frame strengthening i e cementing and or load bearing ice and pore filling ice the model predicted p wave velocities agree well with our laboratory data demonstrating the effectiveness of the model for quantitatively inferring ice content from p wave velocities the modeling workflow is simple and is largely free of calibration paramete

mg sr and sr isotope geochemistry of a belgian holocene speleothem implications for paleoclimate reconstructions in this study variations in mg ca sr ca and 87sr 86sr ratios in a holocene belgian speleothem cave secondary carbonate deposit are interpreted in terms of changes in water residence time and changes in weathering processes possibly induced by changes in west european climate a stalagmite from the pere noel cave belgium was dated with the tims u th method and was deposited between 13 and 2 ka bp the 1000 mg ca ratio varies between 4 9 and 26 and displays short term changes but no significant long term trend the 1000 sr ca ratio varies between 0 09 and 0 31 and displays both short term changes and a long term decreasing trend from 12 9 to 3 5 ka in parallel the sr isotopic composition of the speleothem decreases from 0 7090 at 12 9 ka to 0 7088 at 3 5 ka the sr isotope ratio is higher than expected from the overlying limestone 87sr 86sr 0 7081 which implies an external source of radiogenic sr most probably from a silicate phase short term and long term changes in mg ca sr ca as well as long term changes of 87sr 86sr ratios can be explained by changes in the dissolution and precipitation processes of the host limestone these processes are controlled by changes in water residence times linked to changes in the water excess precipitation minus evapo transpiration c 2000 elsevier science b v all rights reserved

cave air ventilation and co2 outgassing by radon 222 modeling how fast do caves breathe abstract in general the rate and timing of calcite precipitation is in part affected by variations in cave air co2 concentrations knowledge of cave ventilation processes is required to quantify the effect variations in co2 concentrations have on speleothem deposition rates and thus paleoclimate records in this study we use radon 222 222rn as a proxy of ventilation to estimate co2 outgassing from the cave to the atmosphere which can be used to infer relative speleothem deposition rates hollow ridge cave a wild cave preserve in marianna florida is instrumented inside and out with multiple micro meteorological sensor stations that record continuous physical and air chemistry time series data our time series datasets indicate diurnal and seasonal variations in cave air 222rn and co2 concentrations punctuated by events that provide clues to ventilation and drip water degassing mechanisms average cave air 222rn and co2 concentrations vary seasonally between winter 222rn 50 dpm l 1 where 1 dpm l 1 60 bq m 3 co2 360 ppmv and summer 222rn 1400 dpm l 1 co2 3900 ppmv large amplitude diurnal variations are observed during late summer and autumn 222rn 6 to 581 dpm l 1 co2 360 to 2500 ppmv we employ a simple first order 222rn mass balance model to estimate cave air exchange rates with the outside atmosphere ventilation occurs via density driven flow and by winds across the entrances which create a venturi effect the most rapid ventilation occurs 25 m inside the cave near the entrance 45 h 1 1 33 min turnover time farther inside 175 m exchange is slower and maximum ventilation rates are 3 h 1 22 min turnover time we estimate net co2 flux from the epikarst to the cave atmosphere using a co2 mass balance model tuned with the 222rn model net co2 flux from the epikarst is highest in summer 72 mmol m 2 day 1 and lowest in late autumn and winter 12 mmol m 2 day 1 modeled ventilation and net co2 fluxes are used to estimate net co2 outgassing from the cave to the atmosphere average net co2 outgassing is positive net loss from the cave and is highest in late summer and early autumn about 4 mol h 1 and lowest in winter about 0 5 mol h 1 modeling of ventilation net co2 flux from the epikarst and co2 outgassing to the atmosphere from cave monitoring time series can help better constrain paleoclimatic interpretations of speleothem geochemical records

structure of the 8200 year cold event revealed by a speleothem trace element record abrupt first order shifts in strontium and phosphorus concentrations in stalagmite calcite deposited in western ireland during the 8200 year event the major cooling episode 8200 years before the present are interpreted as responses to a drier climate lasting about 37 years both shifts are centered on 8330 80 years before the present coinciding with a large oxygen isotope anomaly and a change in the calcite petrography in this very high resolution monthly record antipathetic second order oscillations in phosphorus and strontium reveal decreased growth rates and increased rainfall seasonality growth rate variations within the event reveal a two pronged structure consistent with recent model simulations

isotopic archives of sulphate in speleothems the hemispheric impact of industrial emissions upon atmospheric sulphur loading is reflected in the sulphur depositional history recorded in cores from ice sheets however these do not reveal regional variations recently deposited speleothems are used here as archives of regional sulphur depositional history at two locations within the united kingdom and ireland 34s so4 and 18o so4 present within speleothem carbonate are measured for the first time as part of a dual isotope approach to decode the speleothem sulphur record the largely refractory nature of 34s so4 under oxidising conditions enables source provenance of atmospheric so2 whereas the complex cycles of isotopic exchange and fractionation during incorporation of oxygen into sulphate molecules enable 18o so4 signatures to yield insights into ambient environmental conditions and biogeochemical cycling in the ecosystem above the cave 34s so4 values extracted from speleothem carbonate formed within browns folly mine uk range from 3 5 to 5 5 and 18o so4 10 3 to 13 7 both signatures lie within the range expected from sulphate deposition in industrial locations and reflect the transfer of sulphate into speleothem calcite with little fractionation however 18o so4 signatures at crag cave western ireland are isotopically heavier than expected and approach isotopic equilibrium with 18o h2o under reducing conditions dual isotope analysis of 34s so4 and 18o so4 optimises the correct identification of sulphur sources and biogeochemical cycling prior to incorporation into the speleothem record at carefully selected cave sites where drip water flowpaths into the cave remain oxic speleothems hold the potential to retain records of atmospheric sulphur loading at the local and regional scale

non linearities in drip water hydrology an example from stump cross caverns yorkshire drip rate data have been collected at 15 min intervals at six locations in stump cross caverns n england since 1998 the different drip sites cover a wide range of drip rates from 2 drips s to 2 drips h and in general the variability of drip rate increases with mean drip rate in our continuous data sampling we observe rapid discharge increases which appear to be synchronous between drips sites and which can be explained by flow switching of the water overlying the cave during times of high infiltration rate such as intense rain storms or rapid snowmelt a test for non linearity white test in the drip series provides very strong evidence that many of the drip sequences are non linear we conclude that at our drip sites there is a non linear input weather and non linearities within the karst system leading to non linear dripping which is independent of drip rate our results have implications for stalagmite palaeoclimatology where such widespread non linearities have not been taken account of

controls on water drop volume at speleothem drip sites an experimental study summary the growth of speleothem under cave drip sites is closely related to local climate events and provides an increasingly important means of deciphering past climate change since calcite precipitation rates depend on the water discharge at the drip site the drip rate and mass of water drops detaching from stalactites are fundamental controls on speleothem growth and we have investigated factors that control the volume of water drops in this environment the classical investigations on the volume of falling water drops are reviewed but there have been no measurements of the volume of drops detaching from curved surfaces equivalent to tips of stalactites in this study we have used an acoustic drop counting method to measure the variation of the mass of water drops detaching from tubes representing soda straw stalactites and artificial stalactites with spherical terminations representing massive stalactites as a function of tube radius or surface curvature and the drip rate the experimental method corroborates classical measurements of drop mass detaching from tubes and for massive stalactites we derive a simple empirical relationship between drop mass and radius of curvature of a spherical surface based on 100 000 drop counts from artificial stalactites with 19 different radii ranging from 3 6 mm to 500 mm the results of this study allow discharge to be calculated from drip interval measurements and provide a quantitative basis for theoretical modelling of speleothem growth from drip sites

validation of volume continuity method for estimation of cross shore swash flow velocity the use of flow volume continuity to estimate depth averaged cross shore swash flow velocity is validated using appropriate field data swash surface and beach face elevation were measured by a network of ultrasonic altimeters mounted through the swash zone of a sandy beach estimates of cross shore flow velocity derived from these data compare well with concurrent measurements obtained from a vertical array of four electromagnetic current meters emcms significantly the continuity technique allows swash velocity to be estimated throughout the full swash cycle this is not possible using fixed current meters and the new measurements indicate that swash velocity is more negatively skewed than previously observed

geophysical estimation of shallow permafrost distribution and properties in an ice wedge polygon dominated arctic tundra region abstractshallow permafrost distribution and characteristics are important for predicting ecosystem feedbacks to a changing climate over decadal to century timescales because they can drive active layer deepening and land surface deformation which in turn can significantly affect hydrologic and biogeochemical responses including greenhouse gas dynamics as part of the u s department of energy next generation ecosystem experiments arctic we have investigated shallow arctic permafrost characteristics at a site in barrow alaska with the objective of improving our understanding of the spatial distribution of shallow permafrost its associated properties and its links with landscape microtopography to meet this objective we have acquired and integrated a variety of information including electric resistance tomography data frequency domain electromagnetic induction data laboratory core analysis petrophysical studies high resolution digital surface models and color mosaics inferred from kite based

swash zone boundary conditions derived from optical remote sensing of swash zone flow patterns 1 optical remote sensing is used to measure flow patterns in the swash zone timestack images are analyzed to measure the asymmetry and the relative duration of the inflow into the swash zone this varies significantly between individual swashes contrary to the classical analytical swash model for runup induced by bores which predicts a similar flow pattern for all events for swash forced by breaking bores the gradient of the x t locus of flow reversal varies over a wide range and flow reversal can occur simultaneously across the whole swash zone this variation of the gradient of the locus of flow reversal in x t space can be parameterized in terms of a single free variable in recent solutions to the nonlinear shallow water equations which fully defines the swash boundary inflow condition consistent with the theory the horizontal runup the swash period and the swash similarity parameter were observed to be independent of the swash inflow conditions but the flow asymmetry is not only a weak correlation was observed between the swash boundary condition and the iribarren number and beach slope conversely the analysis suggests that the degree of swash swash interaction does influence the swash boundary condition and the resulting internal flow kinematics the variation in inflow conditions is expected to influence the magnitudes of the velocity moments within the swash zone and therefore sediment transport rates

controls on dissolved inorganic carbon and δ13c in cave waters from desoto caverns implications for speleothem δ13c assessments abstract unraveling the factors controlling the carbon chemistry and transport of carbon within extant karst systems has important implications concerning the assessment of time series 13c records of speleothems here we report the results of a 3 year study of total dissolved inorganic carbon dic and 13cdic from cave waters at desoto caverns southeastern usa that offer valuable insight on carbon transport and the accompanied isotope fractionations from end member sources to speleothems dic and 13cdic values of cave waters range from 0 2 to 6 0 mm and 2 7 to 12 9 vpdb respectively dic and 13cdic of seasonal drips show seasonal albeit noisy variability and are inversely related 13cdic 2 49 dic 0 64 r2 0 84 a shallow pool fed by multiple drips shows a bimodal 13cdic distribution with an isotopically heavier mode during winter 4 to 5 vpdb relative to summer months 9 to 10 vpdb a multi year trend of decreasing water availability during the study period is not reflected in a response of cave water carbon chemistry suggesting that rainfall amount may not be a significant controlling factor of the carbon chemistry coupled cave air winter ventilation summer stagnation and varying co2 fluxes through the soil horizon and epikarst exert the strongest influence on seasonal dic and 13cdic variability measured values of high dic and low 13cdic from cave waters collected during the summer early fall closely approximate isotopic equilibrium conditions conversely low dic and high 13cdic values during winter early months indicate kinetically enhanced isotopic fractionations within the cave waters the kinetically enhanced isotopic fractionation of hco 3 partitioned between degassed co2 and precipitated caco3 1000 ln co 2 hco 3 caco 3 ar hco 3 2 is greater by about a factor of two 6 7 0 3 relative to the same isotopic fractionation under equilibrium conditions 3 1 on the basis of 14c mass balance and paired 14c u th measurements we estimate that on average about 23 of c delivered annually by the drips to the aragonite stalagmites is derived from 14c dead dolomite cap while the remainder of 77 is derived from 14c live biomass 13c measurements of aragonite n 12 sampled from the tips of active speleothems during the summer months are consistent with theoretical aragonite 13c values calculated using the shallow pool summer early fall data thus confirming the 13c seasonality in both drips and coeval aragonite 13c values of an active stalagmite section spanning the last 200 years show a normal distribution with a mean of 7 1 1 2 n 81 and a mode of 7 to 8 that are statistically indistinguishable from the annual mean and mode of all dripwaters thus secular time series 13c records of stalagmites at desoto caverns with resolving power 10 1 year will likely carry the imprints of drip annual means that record climate driven 13c seasonal biases

depth resolved physicochemical characteristics of active layer and permafrost soils in an arctic polygonal tundra region author s wu y ulrich c kneafsey t lopez r chou c geller j mcknight k dafflon b soom f peterson j hubbard s abstract 2018 the authors permafrost physicochemical parameters play a key role in controlling the response of permafrost carbon to climate change we studied the physicochemical parameters of permafrost in an arctic tundra region to evaluate 1 how soil parameters vary with depth and whether and how they are interrelated 2 whether and how permafrost soil differs from its overlaying active layer and 3 whether soil property depth relationships are different across geomorphic features e g low flat and high centered polygons we also explored the possible biogeochemical processes that led to these soil characteristics and how they may affect biogeochemical reactions upon permafrost thaw we observed 1 consistent relationships between soil property and depth and between major parameters 2 large contrasts of key soil parameters between active layer and permafrost indicative of potentially different response of the permafrost carbon to warming when compared to the active layer and 3 a correlation between soil hydraulic conductivity and topographic features that impacts soil hydrologic processes our analysis suggests that the permafrost has a marine derived chemical signature that differs from the active layer and shapes the physicochemical fingerprints of the different geomorphic features specifically we revealed the unique signatures of the high center polygons indicative of possible microbial activity at depth g1 m our study suggested consistent key soil parameter depth correlations while demonstrating complex lateral and vertical variabilities these results are valuable for identifying approaches to upscale point based measurements and for improving model parameterization to predict permafrost carbon behavior and feedback under future climate

response of cave air co2 and drip water to brush clearing in central texas implications for recharge and soil co2 dynamics 1 brush removal is commonly conducted to increase water availability in arid areas such as central texas where water resources are stressed the effectiveness of brush clearing to enhance recharge however remains uncertain as numerous studies have yielded contradictory results this study assesses the effects of brush clearing on recharge to a cave at natural bridge caverns central texas by evaluating changes in drip rate drip water compositions cave air co2 concentrations and calcite growth in a cave underlying an area cleared of brush drip sites were monitored for 3 years preclearing and 2 years postclearing at five drip sites beneath and seven drip sites not beneath the surface cleared of brush physical and chemical drip water parameters exhibit preclearing and postclearing variability postclearing drip rate characteristics reflect an initial interval of anomalously heavy rainfall then a longer dry period drip water 87sr 86sr values do not exhibit preclearing to postclearing variation at sites beneath the cleared area and indicate no change in postclearing water residence time significant decreases in postclearing cave air co2 are observed at seven of nine drip sites in the cave beneath the clearing decreases in cave air co2 influence calcite growth which impacts postclearing drip water mg ca and sr ca decreases in cave air co2 immediately following brush clearing suggest that a significant portion of soil co2 respiration is from tree root respiration rather than from soil microbial activity seasonal calcite growth patterns linked to cave air co2 also exhibit variability postclearing and suggest that cave mineral deposits may record historical changes in vegetative cover

an isotopic and modelling study of flow paths and storage in quaternary calcarenite sw australia implications for speleothem paleoclimate records abstract we investigated the distinctive shallow sub surface hydrology of the southwest western australia swwa dune calcarenite using observed rainfall and rainfall 18 o soil moisture cave drip rate and dripwater 18 o over a six year period august 2005 march 2012 a lumped parameter hydrological model is developed to describe water fluxes and drip 18 o comparison of observed data and model output allow us to assess the critical non climatic karst hydrological processes that modify the precipitation 18 o signal and discuss the implications for speleothem paleoclimate records from this cave and those with a similar karst setting our findings include evidence of multiple reservoirs characterised by distinct 18 o values and recharge responses low and high flow sites dripwaters exhibit 18 o variations in wet versus dry years at low flow sites receiving diffuse seepage from the epikarst with an attenuated isotopic composition that approximates mean rainfall recharge from high magnitude rain events is stored in a secondary reservoir which is associated with high flow dripwater that is 1 lower than our monitored low flow sites 18 o one drip site is characterised by mixed flow behaviour and exhibits a non linear threshold response after the cessation of drainage from a secondary reservoir following a record dry year 2006 additionally our results yield a better understanding of the vadose zone hydrology and dripwater characteristics in quaternary age dune limestones we show that flow to our monitored sites is dominated by diffuse flow with inferred transit times of less than one year diffuse flow appears to follow vertical preferential paths through the limestone reflecting differences in permeability and deep recharge into the host rock

centennial scale holocene climate variability revealed by a high resolution speleothem δ18o record from sw ireland evaluating the significance of holocene submillennial 18 o variability in the greenland ice cores is crucial for understanding how natural climate oscillations may modulate future anthropogenic warming a high resolution oxygen isotope record from a speleothem in southwestern ireland provides evidence for centennial scale 18 o variations that correlate with subtle 18 o changes in the greenland ice cores indicating regionally coherent variability in the early holocene evidence for previously undetected early holocene cooling events is presented but mid to late holocene ice rafting in the north atlantic appears to have had little impact on 18 o at this ocean margin site

conservation of soil organic matter through cryoturbation in arctic soils in siberia 1 cryoturbation mixing of soil layers due to repeated freeze thaw processes is a major soil forming process in arctic regions which may contribute to long term storage of c in soils of northern latitudes our goal was to determine the effect of subduction of organic matter by cryoturbation on microbial decomposition processes in tundra soils buried layers were situated at 30 60 cm depth between bg and b horizons but exhibited a c and n content highly similar to present day a horizons radiocarbon dating revealed however that the mean age of c in the buried layer was three times higher 1300 years bp than in the a horizon 400 years bp suggesting that decomposition rates in the buried layer were delayed the observed microbial processes support this result gross c and n mineralization rates were substantially lower in the buried layers than in the respective a horizons the amount of c stored in the buried layer still doubles the amount of c stored in topsoil horizons o and a assuming that the buried layer originates from both o and a horizons this indicates that o and a horizon at time of burying 800 1300 years bp must have been significantly thicker and present day o and a horizon at this site may still have the capacity to accumulate additional c cryoturbation therefore may lead to additional long term storage of carbon in the system by 1 retarding decomposition processes of buried organic material and 2 enabling the soil to restart c accumulation in topsoil layers

biomass effects on stalagmite growth and isotope ratios a 20th century analogue from wiltshire england increases in calcite deposition rates combined with decreases in 13c and 18o in three modern stalagmites from brown s folly mine wiltshire england are correlative with a well documented re vegetation above the mine increased soil pco2 resulted in greater amounts of dissolved caco3 in the drip waters which consequently increased annual calcite deposition rates the absence of deposition prior to 1916 28 years after the mine was closed indicates that vegetation had not yet sufficiently developed to allow higher pco2 values to form in the soil lower 13c values through time may reflect the increased input of isotopically light biogenic carbon to the total dissolved inorganic carbon dic 18o decreased synchronously with 13c reflecting the increased importance of isotopically light winter recharge due to greater biomass induced summer evapotranspiration this is the first empirical demonstration that vegetation density can control stalagmite growth rates 13c and 18o contributing critical insights into the interpretation of these climate proxies in ancient stalagmites

inverse modelling of the 14c bomb pulse in stalagmites to constrain the dynamics of soil carbon cycling at selected european cave sites the decomposition of soil organic matter som is temperature dependent but its response to a future warmer climate remains equivocal enhanced rates of decomposition of som under increased global temperatures might cause higher co2 emissions to the atmosphere and could therefore constitute a strong positive feedback the magnitude of this feedback however remains poorly understood primarily because of the difficulty in quantifying the temperature sensitivity of stored recalcitrant carbon that comprises the bulk 90 of som in most soils in this study we investigated the effects of climatic conditions on soil carbon dynamics using the attenuation of the 14c bomb pulse as recorded in selected modern european speleothems these new data were combined with published results to further examine soil carbon dynamics and to explore the sensitivity of labile and recalcitrant organic matter decomposition to different climatic conditions temporal changes in 14c activity inferred from each speleothem was modelled using a three pool soil carbon inverse model applying a monte carlo method to constrain soil carbon turnover rates at each site speleothems from sites that are characterised by semi arid conditions sparse vegetation thin soil cover and high mean annual air temperatures maats exhibit weak attenuation of atmospheric 14c bomb peak a low damping effect d in the range 55 77 and low modelled mean respired carbon ages mrca indicating that decomposition is dominated by young recently fixed soil carbon by contrast humid and high maat sites that are characterised by a thick soil cover and dense well developed vegetation display the highest damping effect d c 90 and the highest mrca values in the range from 350 126 years to 571 128 years this suggests that carbon incorporated into these stalagmites originates predominantly from decomposition of old recalcitrant organic matter som turnover rates cannot be ascribed to a single climate variable e g maat but instead reflect a complex interplay of climate e g maat and moisture budget and vegetation development

identifying multiscale zonation and assessing the relative importance of polygon geomorphology on carbon fluxes in an arctic tundra ecosystem we develop a multiscale zonation approach to characterize the spatial variability of arctic polygonal ground geomorphology and to assess the relative controls of these elements on land surface and subsurface properties and carbon fluxes working within an ice wedge polygonal region near barrow alaska we consider two scales of zonation polygon features troughs centers and rims of polygons that are nested within different polygon types high flat and low centered in this study we first delineated polygons using a digital elevation map and clustered the polygons into four types along two transects using geophysical and kite based landscape imaging data sets we extrapolated those data defined polygon types to all the polygons over the study site using the polygon statistics extracted from the digital elevation map based on the point measurements we characterized the distribution of vegetation hydrological thermal and geochemical properties as well as carbon fluxes all as a function of polygon types and polygon features results show that nested polygon geomorphic zonation polygon types and polygon features can be used to represent distinct distributions of carbon fluxes and associated properties as well as covariability among those properties importantly the results indicate that polygon types have more power to explain the variations in those properties than polygon features the approach is expected to be useful for improved system understanding site characterization and parameterization of numerical models aimed at predicting ecosystem feedbacks to the climate

cave air control on dripwater geochemistry obir caves austria implications for speleothem deposition in dynamically ventilated caves there are very few process studies that demonstrate the annual variation in cave environments depositing speleothems accordingly we initiated a monitoring program at the obir caves an austrian dripstone cave system characterized by a seasonally changing air flow that results in a predictable pattern of high pco2 during summer and low pco2 in winter although similar seasonal changes in soil pco2 occur they are not directly connected with the changes in the subsurface since the dripwaters are fed from a well mixed source showing little seasonal variation cold season flushing by relatively co2 poor air enhances degassing of co2 in the cave and leads to a high degree of supersaturation of dripwater with regard to calcite forced calcite deposition during the cold season also gives rise to a pronounced pattern of synchronous seasonal variations in electrical conductivity alkalinity ph ca and 13cdic which parallel variations recorded in 13ccave air chemical components unaffected by calcite precipitation e g d 18o sio2 so4 lack a seasonal signal attesting to a long residence in the karst aquifer modeling shows that degassing of co2 from seepage waters results in kinetically enhanced c isotopic fractionation which contrasts with the equilibrium degassing shown from the soreq cave in israel the obir caves may serve as a case example of a dripstone cave whose seepage waters and speleothems show intra annual geochemical variability that is primarily due to chemical modification of the groundwater by a dynamic bidirectional subsurface air circulation

annual to sub annual resolution of multiple trace element trends in speleothems this study aims to establish evidence for the widespread existence of preserved high resolution trace element variations in speleothems that may have climatic significance ion microprobe analysis of speleothems reveals that annual to sub annual variations in element chemistry exist at five shallow western european cave sites crag cave county kerry and ballynamintra county waterford ireland uamh an tartair sutherland scotland grotte pere noel belgium grotta di ernesto ne italy with widely varying climatic geomorphic and geological settings the variations are not restricted to species mg sr and ba known to substitute directly for ca in the calcite lattice but include h f na and p phosphorus as phosphate displays the greatest variability and may have the most significance as a proxy for the seasonal temperature cycle because of its role as a nutrient element the technique allows estimation of growth rate of speleothems at any interval of interest which is one of several possible uses in palaeoclimatology

climatic and environmental controls on speleothem oxygen isotope values variations in speleothem oxygen isotope values d 18 o result from a complicated interplay of environmental controls and processes in the ocean atmosphere soil zone epikarst and cave system as such the controls on speleothem d 18 o values are extremely complex an understanding of the processes that control equilibrium and kinetic fractionation of oxygen isotopes in water and carbonate species is essential for the proper interpretation of speleothem d 18 o as paleoclimate and paleoenvironmental proxies and is best complemented by study of site specific cave processes such as infiltration flow routing drip seasonality and saturation state and cave microclimate among others this review is a process based summary of the multiple controls on d 18 o in the atmosphere soil epikarst and speleothem calcite illustrated with case studies primary controls of d 18 o in the atmosphere include temperature and relative humidity through their role in the multiple isotope effects variability and modifications of water d 18 o values in the soil and epikarst zones are dominated by evaporation mixing and infiltration of source waters the isotopically effective recharge into a cave system consists of those waters that participate in precipitation of caco3 resulting in calcite deposition rates which may be biased to time periods with optimal dripwater saturation state recent modeling experimental and observational data yield insight into the significance of kinetic fractionation between dissolved carbonate phases and solid caco3 and have implications for the hendy test to assist interpretation of speleothem d 18 o time series quantitative and semi quantitative d 18 o climate calibrations are discussed with an emphasis on some of the difficulties inherent in using modern spatial and temporal isotope gradients to interpret speleothems as paleoclimate proxy records finally several case studies of globally significant speleothem paleoclimate records are discussed that show the utility of d 18 o to reconstruct past climate

grain size properties and organic carbon stock of yedoma ice complex permafrost from the kolyma lowland northeastern siberia the organic carbon stock in permafrost is of increasing interest in environmental research because during the late quaternary a large pool of organic carbon accumulated in the sedimentary deposits of arctic permafrost because of its potential to degrade and release organic carbon the organic matter inventory of yedoma ice complex deposits is relevant to current concerns about the effects of global warming in this context it is essential to improve the understanding of preserved carbon quantities and characteristics the paper aims to clarify the yedoma ice complex origin and to develop an approach for volumetric organic matter quantification therefore we analyzed the grain size and the organic matter characteristics of the deposits exposed at the stratigraphic key site duvanny yar lower kolyma river northeast siberia a distinct bimodal grain size distribution confirms a polygenetic origin of the frozen sediments from a flood plain environment the total organic carbon content averages 1 5 1 4 wt while the volumetric organic carbon content averages 14 8 kg m however large scale extrapolations for yedoma ice complex deposits in general are not reasonable yet because of their rather unclear spatial distribution we conclude that yedoma ice complex formation at duvanny yar was dominated by water related alluvial fluvial lacustrine as well as aeolian processes the total organic carbon content of the studied deposits is low if compared to other profiles but it is still a significant pool

monitoring of selected caves as a prerequisite for the speleothem based reconstruction of the quaternary environment in croatia abstract quaternary palaeo environmental changes that have taken place in croatia are likely to be recorded in speleothems secondary carbonate deposits precipitated in caves confident interpretation of well dated speleothem proxy records relies on modern monitoring programs which we provided in three regionally different caves parallel monitoring of the surface and cave air temperature and relative humidity precipitation and cave drip intensity as well as stable isotope modification of meteoric and drip water was carried out in order to estimate the most reliable stalagmites for the interpretation of quaternary landscape history in all three caves nova grgosova 239 m a s l t cave 11 2 c in central croatia lokvarka 780 m a s l t cave 7 5 c in the mountainous part of croatia and modric 32 m a s l t cave 16 6 c in coastal croatia we selected the parts of the caves where the ambient cave conditions appeared to be appropriate for equilibrium deposition of calcite in terms of constant air temperature seasonal amplitudes of 0 73 0 38 and 0 45 c respectively and relative humidity 100 both atlantic and mediterranean moisture influences were detected in all three caves but of different intensities cave hydrological settings governed by karst aquifer properties were resolved by the comparison of the precipitation intensities and drip site responses to the rain events and generally seasonal rainwater isotopic signal was almost completely attenuated except for one drip site such homogenized drip water and stable cave environmental settings give confidence for calcite deposition under equilibrium conditions especially for modric and nova grgosova caves where speleothems inner structures also look promising for potentially quality dating results and stable isotopic profiles the fracture flow drip regime of selected drip sites in lokvarka cave and uncompleted homogenization of the water in the epikarst might point to speleothem samples that are unsuitable for resolving multi annual quaternary climate changes this view is supported by the high porosity internal structure of some lokvarka speleothems so further monitoring sampling and the thorough speleothem examination is therefore necessary for adequate interpretations of palaeo environmental changes