spreading of greenland meltwaters in the ocean revealed by noble gases we present the first noble gas observations in a proglacial fjord in greenland providing an unprecedented view of surface and submarine melt pathways into the ocean using optimum multiparameter analysis noble gas concentrations remove large uncertainties inherent in previous studies of meltwater in greenland fjords we find glacially modified waters with submarine melt concentrations up to 0 66 0 09 and runoff 3 9 0 29 radiogenic enrichment of helium enables identification of ice sheet near bed melt 0 48 0 08 we identify distinct regions of meltwater export reflecting heterogeneous melt processes a surface layer of both runoff and submarine melt and an intermediate layer composed primarily of submarine melt intermediate ocean waters carry the majority of heat to the fjords glaciers and warmer deep waters are isolated from the ice edge the average entrainment ratio implies that ocean water masses are upwelled at a rate 30 times the combined glacial meltwater volume flux

physical and biological controls on oxygen saturation variability in the upper arctic ocean employing continuous in situ measurements of dissolved o2 ar and o2 in the arctic ocean we investigate the mechanisms controlling the physical abiotic and biological oxygen saturation state variability in the surface ocean beneath sea ice o2 ar measurements were made underway using equilibrator inlet mass spectrometry eims during an icebreaker survey transiting the upper arctic ocean across the north pole in late summer 2011 using concurrently collected measurements of total oxygen we devolve biological oxygen saturation and physical oxygen ar saturation signals at unprecedented horizontal resolution in the surface ocean in the nansen basin ar is undersaturated up to 7 while biological oxygen supersaturation peaks at 18 4 we attribute this to ice melt atlantic water influence and or cooling in the canadian basin ar is supersaturated up to 3 likely because of ar injection from freezing processes and long residence times of gas under ice cover the overall canadian basin to eurasian basin gradient of ar supersaturation to undersaturation may reflect net freezing in the canadian basin and net melting in the eurasian basin over several seasons either by pacific to atlantic sector ice transport or local changes over time ar saturation could thereby provide large scale high resolution estimates of current and future changes in these processes o2 ar supersaturation averages 4 9 with peaks up to 9 8 where first year ice and abundant melt ponds likely allow sufficient light for blooms in ice covered regions

response of daily and annual shell growth patterns of the intertidal bivalve phacosoma japonicum to holocene coastal climate change in japan abstract it is well known that the latitudinal distribution of shallow marine mollusks around the japanese islands has changed episodically during the holocene in response to climate change however few studies have investigated the biotic response of individual species to holocene climate change at daily to annual scales of temporal resolution holocene shells of the venerid phacosoma japonicum recovered from various sites in japan preserve lunar daily and annual growth increments in the outer shell layer and hinge plate as also observed in modern shells sclerochronological analysis of 29 shells with known 14 c ages revealed that the life history traits e g length of the growth period and the mean lunar daily growth rate at a given age have changed markedly over the past 8000 years the intra annual patterns of lunar daily increments and shell oxygen isotope records of the fossil shells can be compared with those of modern specimens from various locations which are constrained by annual patterns of seawater temperature and summer autumn precipitation rates furthermore the temporal trends recorded in the fossil shells show a strong correlation with climate change in mid latitude parts of east asia over the past 8000 years indicating that p japonicum has changed its life history traits in response to holocene terrestrial and coastal climate change

biological and physical controls on n2 o2 and co2 distributions in contrasting southern ocean surface waters we present measurements of pco2 o2 concentration biological oxygen saturation o2 ar and n2 saturation n2 in southern ocean surface waters during austral summer 2010 2011 phytoplankton biomass varied strongly across distinct hydrographic zones with high chlorophyll a chl a concentrations in regions of frontal mixing and sea ice melt pco2 and o2 ar exhibited large spatial gradients range 90 to 450 atm and 10 to 60 respectively and covaried strongly with chl a however the ratio of biological o2 accumulation to dissolved inorganic carbon dic drawdown was significantly lower than expected from photosynthetic stoichiometry reflecting the differential time scales of o2 and co2 air sea equilibration we measured significant oceanic co2 uptake with a mean air sea flux 10 mmol m 2 d 1 that significantly exceeded regional climatological values n2 was mostly supersaturated in surface waters mean n2 of 2 5 while physical processes resulted in both supersaturation and undersaturation of mixed layer o2 mean o2phys 2 1 box model calculations were able to reproduce much of the spatial variability of n2 and o2phys along the cruise track demonstrating significant effects of air sea exchange processes e g atmospheric pressure changes and bubble injection and mixed layer entrainment on surface gas disequilibria net community production ncp derived from entrainment corrected surface o2 ar data ranged from 40 to 300 mmol o2 m 2 d 1 and showed good coherence with independent ncp estimates based on seasonal mixed layer dic deficits elevated ncp was observed in hydrographic frontal zones and stratified regions of sea ice melt reflecting physical controls on surface water light fields and nutrient availability

holocene alluvial sediment storage in a small river catchment in the loess area of central belgium abstract soil erosion and sediment deposition widely affect landscape development particularly in erosion prone areas with loess derived soils nevertheless until now few attempts were made to quantify soil losses and sediment storage over long centennial or millennial timescales in this study the holocene alluvial sediment storage in a small river catchment 52 km2 of the belgian loess belt is estimated and a preliminary sediment budget for the catchment is presented in the valley of the nethen river c 13 km long a detailed survey of the alluvial sediment archive was conducted hand augerings and percussion drillings were made along cross valley transects at 12 locations in the catchment ams 14c dating of peat samples provided a temporal framework for the interpretation of the cores results show that the thickness of holocene sediment deposits in the nethen valley is 4 to 6 m which corresponds to a total clastic sediment mass of 14 106 t stored in the valley bottom three alluvial units could be distinguished and associated with deposition phases from 9600 to 2900 b c 2900 b c to a d 1000 and a d 1000 to present in contrast to the older sediments units 1 and 2 deposits from the last 1000 year unit 3 contain little organic matter they are seldom intercalated with peat layers and devoid of tufa unit 3 reaches a thickness of c 2 m thereby representing 50 of the holocene sediment mass stored in the alluvial plain the mean sedimentation rate in the alluvial plain for this last phase is 26 t ha 1 a 1 which is about tenfold larger than the sedimentation rates calculated for the older holocene sediment units sediment supply towards the alluvial plain has therefore increased tremendously since medieval times these results are in contrast to dating results obtained for colluvial sediments in a nearby dry valley within the catchment of the nethen where soil erosion and sediment deposition started in the early iron age and was already substantial during the roman age this means that there is a time lag of about one millennium between the onset of high sedimentation rates in the upstream area and high deposition rates in the alluvial plain this is probably caused by a change in coupling sediment connectivity between the plateau slopes and rivers as soil erosion proceeds first the dry zero order valleys in the catchment act as sediment traps and only after these are filled sediment reaches the floodplains the preliminary sediment budget for the nethen catchment illustrates that 50 of the sediment that was eroded during the holocene was stored in colluvial deposits which are mainly located on footslopes and in dry valley bottoms another 29 of the sediment mass is stored in the alluvial plain

modelling differential catchment response to environmental change the caesar cellular automaton evolutionary slope and river model is used to demonstrate significant differences in coarse sediment transfer and alluviation in medium sized catchments when responding to identical holocene environmental changes simulations for four u k basins the rivers swale ure nidd and wharfe shows that catchment response driven by climate and conditioned by land cover changes is synchronous but varies in magnitude there are bursts of sediment transfer activity generally of rapid removal but with some sediment accumulation dspikest with longer periods of slow removal or accumulation of sediment in different valley reaches within catchments reach sensitivity to environmental change varies considerably some periods are only recorded in some reaches whilst higher potential sensitivity typically occurs in the piedmont areas of the catchments modelled here these differential responses appear to be highly non linear and may relate to the passage of sediment waves by variable local sediment storage and availability and by large and small scale thresholds for sediment transfer within each catchment differential response has major implications for modelling fluvial systems and the interpretation of field data model results are compared with the record of dated alluvial deposits in the modelled catchments d 2005 elsevier b v all rights reserved

phases of soil erosion derived colluviation in the loess hills of south germany in south germany soil erosion is as old as farming and dates back to early neolithic times its sedimentary products form thick colluvial and alluvial sediment bodies in all drainage basins numerous local studies exist but the extrapolation of findings from local case studies to a regional scale has been problematic here a graphical approach is used for frequency analysis of existing data a frequency distribution for optical dates on colluvial sediments from the beginning of agriculture until 1200 ad was constructed by 1 representing the optical ages by gaussian distributions and 2 summing all the single curves the resulting graph clearly shows phases of increased colluviation during periods of stronger human impact a first significant increase occurred during the bronze age during the iron age roman period and at around 800 ad distinct maxima appear in the distribution and highest frequencies are present towards the end of the analysed period at around 1100 ad conclusions that can be drawn from such an approach are limited by sampling bias and other factors but for the analysed period and on a regional and long term scale colluviation seems to have been mainly triggered by intensity of land use climatic fluctuations are of only secondary importance rainfall events that were sufficiently erosive to produce colluvial sediments occurred throughout the agricultural periods the limiting factor for colluvium production was sensitivity of the landscape to erosion and this is a result of land use d 2002 elsevier science b v all rights reserved

the processes and timing of sediment delivery from headwaters to the trunk stream of a central european mountain gully catchment abstract gully systems determine downstream water quality and sediment loads since they are located where streams begin they are often only considered as a sediment source and the degree to which gully systems also store sediment and the timescales of this storage have received less attention gully sediment storage is important because many sedimentary archives such as floodplains and lakes have recorded increases in sedimentation rates particularly in medieval times which are interpreted as the result of increased slope erosion and gully activity at present there is insufficient evidence directly linking such other sedimentary archives and gully systems there is also a lack of long term records which may indicate how the major external controls climatic or anthropogenic might determine gully responses to address this we analysed sediment sources and sinks within a small 43 ha gully catchment in the spessart mountains germany we found five main phases of erosion and deposition since 13 ka which revealed catchment vegetation significantly controlled geomorphic responses a loss of vegetation due to climate deterioration e g younger dryas or deforestation e g medieval period caused widespread slope instability and the aggradation of the gully thalweg in contrast well forested conditions before the medieval period and again in recent years re stabilised the slopes leading to gully incision with knickpoint retreat this result differs from previous interpretations of gully activity in central europe that gully erosion mostly occurred in medieval times our results also demonstrate that only the initial phase of knickpoint retreat is significant for supplying sediment to the gully fan and trunk stream then knickpoint retreat leads to a relative increase in the thalweg storage capacity downstream which limits further sediment export this has important implications for the interpretation of floodplain ages since the initial supply of gully sediment to trunk streams may not coincide with human impact instead there will be a lagged response between catchment reforestation and the onset of gully incision which in this study is up to 150 years therefore the assumption of a direct causal link between increases in floodplain sedimentation and slope erosion may not always be valid

factors controlling sediment yield from small intensively cultivated catchments in a temperate humid climate abstract data on sediment yield from 26 small cultivated catchments 10 10 000 ha in central belgium were collected based on sedimentation rates in small flood retention ponds area specific sediment yield varies from 0 4 to 20 6 t ha 1 year 1 for catchments ranging from 7 to 4873 ha various catchment properties were analysed in order to understand this large variation in sediment yield catchment area alone explains 64 of the observed variance in area specific sediment yield although no other parameter could explain more it is concluded that catchment area is not a valid parameter to link with sediment yield overall catchment geomorphology e g presented by the hypsometric integral is much more important in controlling sediment yield the lack of data however made this not very clear a multiple regression model including three morphological catchment properties is a valuable tool to predict total sediment yield t year 1 from catchments in central belgium this model has an efficiency of 0 81 furthermore it was concluded that the within catchment spatial distribution of parameters for instance slope steepness is very important but difficult to obtain one single representative value the use of spatially distributed erosion and sediment delivery models is therefore necessary accurate sediment yield data like the one presented in this study however are needed to validate these models

fluvial sediment budgets in the north carolina piedmont phillips j d 1991 fluvial sediment budgets in the north carolina piedmont geomorphology 4 231 241 sediment budgets for four large 1000 km 2 drainage basins in the piedmont physiographic province of north carolina were estimated from data compiled during erosion and sedimentation surveys budgets for the upper tar upper neuse haw and deep river basins showed broadly similar trends in allocation of eroded sediment among yield and storage sediment yield as a percentage of mean annual gross erosion within the basins averaged 10 this was less than the rate of alluvial storage which averaged 14 of annual gross erosion about 76 of the mean annual erosion was stored as colluvium on hillslopes there are relatively small differences in sediment delivery and storage ratios among the study basins this suggests that the relative order of magnitude of the allocation of eroded sediment for southern piedmont rivers is colluvial storage alluvial storage and yield of the sediment that does reach the streams more than half is stored as alluvium on an average annual basis aggrading channels and floodplains siltation of benthic habitats and sediment pollution problems are thus likely to persist unless dramatic reductions in upland erosion or in sediment delivery to streams are realized with respect to longer term basin evolution results point to the need for an improved understanding of the temporal scales of colluvial and alluvial sediment storage

large variations in holocene solar activity constraints from 10be in the greenland ice core project ice core 1 cosmogenic radionuclides extracted from ice cores hold a unique potential for reconstructing past solar activity changes beyond the direct instrumental period taking the geomagnetic modulation into account the solar activity in terms of the heliospheric modulation function can quantitatively be reconstructed in high resolution throughout the holocene for this period our results reveal changes in heliospheric modulation of galactic cosmic rays significantly larger than the variations reconstructed on the basis of neutron monitor measurements of galactic cosmic rays for the last 50 years moreover the 10be data from the greenland ice core project ice core as well as 14c support a high current solar activity however although the reconstruction of solar activity on long timescales is difficult our result suggests that the modern activity state of the sun is not that exceptional regarding the entire holocene this extended solar activity record provides the basis for further detailed investigations on solar and cosmic ray physics as well as on solar forcing of the earth s climate whose importance is suggested by increasing paleoclimatic evidences

explosive volcanic eruptions triggered by cosmic rays volcano as a bubble chamber abstract volcanoes with silica rich and highly viscous magma tend to produce violent explosive eruptions that result in disasters in local communities and that strongly affect the global environment we examined the timing of 11 eruptive events that produced silica rich magma from four volcanoes in japan mt fuji mt usu myojin sho and satsuma iwo jima over the past 306 years from ad 1700 to ad 2005 nine of the 11 events occurred during inactive phases of solar magnetic activity solar minimum which is well indexed by the group sunspot number this strong association between eruption timing and the solar minimum is statistically significant to a confidence level of 96 7 this relationship is not observed for eruptions from volcanoes with relatively silica poor magma such as izu ohshima it is well known that the cosmic ray flux is negatively correlated with solar magnetic activity as the strong magnetic field in the solar wind repels charged particles such as galactic cosmic rays that originate from outside of the solar system the strong negative correlation observed between the timing of silica rich eruptions and solar activity can be explained by variations in cosmic ray flux arising from solar modulation because silica rich magma has relatively high surface tension 0 1 nm 1 the homogeneous nucleation rate is so low that such magma exists in a highly supersaturated state without considerable exsolution even when located relatively close to the surface within the penetration range of cosmic ray muons 1 10 gev these muons can contribute to nucleation in supersaturated magma as documented by many authors studying a bubble chamber via ionization loss this radiation induced nucleation can lead to the pre eruptive exsolution of h 2 o in the silica rich magma we note the possibility that the 1991 mt pinatubo eruption was triggered by the same mechanism an increase in cosmic ray flux triggered by typhoon yunya as a decrease in atmospheric pressure results in an increase in cosmic ray flux we also speculate that the snowball earth event was triggered by successive large scale volcanic eruptions triggered by increased cosmic ray flux due to nearby supernova explosions

soil erosion in small catchments of the quercy region southwester france during the holocene erosion rates in two small catchments of the quercy region southwestern france calculated from colluvial deposits trapped in karstic depressions show a progressive increase during the holocene rates lower than 0 2 t ha 1 yr 1 have been found for the period that covers the beginning of the holocene to the early iron age the soils buried in the depressions testify to the permanence of a forest cover until the late neolithic and to its replacement by a herbaceous vegetation during protohistorical times probably as a consequence of forest clearance and increased grazing by cattle after the early iron age erosion increased significantly and the mean rate reached 0 8 t ha 1 yr 1 before mediaeval times the associated coarse grained crudely stratified colluvium is thought to reflect ploughing of the surrounding fields erosion rate increased up to c 1 3t ha 1 yr 1 during mediaeval and modem times

temperature trends over the past five centuries reconstructed from borehole temperatures for an accurate assessment of the relative roles of natural variability and anthropogenic influence in the earth s climate reconstructions of past temperatures from the pre industrial as well as the industrial period are essential but instrumental records are typically available for no more than the past 150 years therefore reconstructions of pre industrial climate rely principally on traditional climate proxy records each with particular strengths and limitations in representing climatic variability subsurface temperatures comprise an independent archive of past surface temperature changes that is complementary to both the instrumental record and the climate proxies here we use present day temperatures in 616 boreholes from all continents except antarctica to reconstruct century long trends in temperatures over the past 500 years at global hemispheric and continental scales the results confirm the unusual warming of the twentieth century revealed by the instrumental record but suggest that the cumulative change over the past five centuries amounts to about 1 k exceeding recent estimates from conventional climate proxies the strength of temperature reconstructions from boreholes lies in the detection of long term trends complementary to conventional climate proxies but to obtain a complete picture of past warming the differences between the approaches need to be investigated in detail

biological and physical controls on o 2 ar ar and p co 2 variability at the western antarctic peninsula and in the drake passage abstract using simultaneous sub kilometer resolution underway measurements of surface o2 ar total o2 and pco2 from annual austral summer surveys in 2012 2013 and 2014 we explore the impacts of biological and physical processes on the o2 and pco2 system spatial and interannual variability at the western antarctic peninsula wap in the wap mean o2 ar supersaturation was 7 6 9 1 and mean pco2 supersaturation was 28 22 we see substantial spatial variability in o2 and pco2 including sub mesoscale mesoscale variability with decorrelation length scales of 4 5 km consistent with the regional rossby radius this variability is embedded within onshore offshore gradients o2 in the lter grid region is driven primarily by biological processes as seen by the median ratio of the magnitude of biological oxygen o2 ar to physical oxygen ar supersaturation anomalies relative to atmospheric equilibrium 2 6 however physical processes have a more pronounced influence in the southern onshore region of the grid where we see active sea ice melting total o2 measurements should be interpreted with caution in regions of significant sea ice formation and melt and glacial meltwater input pco2 undersaturation predominantly reflects biological processes in the lter grid in contrast we compare these results to the drake passage where gas supersaturations vary by smaller magnitudes and decorrelate at length scales of 12 km in line with latitudinal changes in the regional rossby radius here biological processes induce smaller o2 ar supersaturations mean 0 14 1 3 and pco2 undersaturations mean 2 8 3 9 than in the wap and pressure changes bubble and gas exchange fluxes drive stable ar supersaturations

time integrated 3d approach of late quaternary sediment depocenter migration in the tagus depositional system from river valley to abyssal plain quantification of sediment volumes in continental to deep ocean basins is key to understanding processes of sediment distribution in source to sink depositional systems using our own and published data we present the first quantification of sediment volume changes in basins along the course of a major southwest european river during the deglaciation the salient points of this quantitative record in the tagus and equivalent north atlantic basins show crucial roles for sea level climate and land use in the distribution of sediments the bypass of sediments starved the tagus basins and subsequently sedimentation mainly occurred on the tagus abyssal plain during the sea level lowstand of the last glacial maximum the main sediment depocenter rapidly shifted via the continental shelf to the lower tagus valley during sea level rise in the deglaciation period finally the main sediment depocenter shifted further landward into the lower tagus valley during sea level high stand in the holocene during the high stand phase last 7 ky sediment flux increased up to 2 5 times due to climate and land use changes the average catchment denudation rate during the last 12 ky 0 04 0 1 mm y is in agreement with those of other european catchments our study clearly demonstrates the added value of detailed knowledge of 3d depocenter distribution size and chronology this allowed us to identify an increased sediment flux during the last 7 ky which was not identified using local observations from boreholes alone the uniqueness of the tagus depositional system lies in the combination of a large accommodation space in the bedrock confined lower tagus valley the steep lowstand surface gradient and the narrow continental shelf with canyons indenting the shelf break

possible link between multi decadal climate cycles and periodic reversals of solar magnetic field polarity abstract the linkage between multi decadal climate variability and activity of the sun has been long debated based upon observational evidence from a large number of instrumental and proxy records it is difficult to evaluate the exact role of each of solar parameters on climate change since instrumentally measured solar related parameters such as total solar irradiance tsi ultra violet uv solar wind and galactic cosmic rays gcrs fluxes are more or less synchronized and only extend back for several decades here we report tree ring carbon 14 based record of 11 year 22 year solar cycles during the maunder minimum 17th century and the early medieval maximum period 9 10th century to reconstruct the state of the sun and the flux of incoming gcrs the result strongly indicates that the influence of solar cycles on climate is persistent beyond the period after instrumental observations were initiated we find that the actual lengths of solar cycles vary depending on the status of long term solar activity and that periodicity of the surface air temperatures are also changing synchronously temperature variations over the 22 year cycles seem in general to be more significant than those associated with the 11 year cycles and in particular around the grand solar minima such as the maunder minimum 1645 1715 ad the polarity dependence of cooling events found in this study suggests that the gcrs can not be excluded from the possible drivers of decadal to multi decadal climate change

nao signal recorded in the stable isotopes of greenland ice cores 1 the winter 18o signal is extracted from 7 greenland ice cores covering the past 700 years to filter out noise and local variations in the 7 isotope records a principal component analysis is carried out on the ice core data a comparison between the time series of the first principal component pc1 with 67 years of winter december to march temperature measurements from 3 southern greenland synoptic stations shows highly significant correlations southern greenland winter temperatures are known to be greatly influenced by the north atlantic oscillation nao a good proxy for southern greenland temperatures is therefore expected to reveal at least parts of the nao signal it is shown that the pc1 time series indeed is significantly correlated to the nao during the winter months the inclusion of ice core winter season 18o time series in future multiproxy nao reconstructions is therefore recommended

the five stable noble gases are sensitive unambiguous tracers of glacial meltwater the five inert noble gases he ne ar kr and xe exhibit a unique dissolved gas saturation pattern resulting from the formation and addition of glacial meltwater to seawater he and ne become oversaturated and ar kr and xe become undersaturated to varying percentages for example addition of 10 glacial meltwater to seawater results in a saturation anomaly of he 12 8 ne 8 9 ar 0 5 kr 2 2 and xe 3 3 this pattern in noble gas saturation reflects a unique meltwater signature that is distinct from the other major physical processes that modify the gas concentration and saturation namely seasonal changes in temperature at the ocean surface and bubble mediated gas exchange we use optimum multiparameter analysis to illustrate how all five noble gases can help distinguish glacial meltwater from wind driven bubble injection making them a potentially valuable suite of tracers for glacial melt and its concentration in the deep waters of the world ocean

gully catchments as a sediment sink not just a source results from a long term 12 500 year sediment budget sediment delivery from hillslopes to trunk streams represents a significant pathway of mass transfer in the landscape with a large fraction facilitated by gully systems the internal gully geomorphic dynamics represent a considerable gap in many landscape and empirical erosion models therefore a better understanding of these processes over longer timescales 10 10 years is needed this study analyses the sediment mass balance and storage dynamics within a headwater gully catchment in central europe over the last 12 500 years human induced erosion resulted in hillslope erosion rates 2 3 times higher than under naturally de vegetated conditions during the younger dryas however the total sediment inputs to the gully system and therefore gully aggradation were similar net gully storage has consistently increased to become the second largest term in the sediment budget after hillslope erosion storage is 45 and 73 of inputs during two separate erosion and aggradation cycles in terms of the depletion of gully sediment storage the sediment mass balance shows that export beyond the gully fan was not significant until the last 500 years due to reduced gully fan accommodation space the significance of storage effects on the gully sediment mass balance particularly the export terms means that it would be difficult to determine the influences of human impact and or climatic changes from floodplain or lake sedimentary archives alone and that the sediment budgets of the headwater catchments from which they drain are more likely to provide these mechanistic links

prehistoric and roman gullying in the european oess belt a case study from central belgium in contrast with the understanding of present day soil erosion processes knowledge on past soil erosion phenomena is still rather limited although some studies report on severe gully erosion phases during the fourteenth and eighteenth centuries almost no evidence is available that documents earlier gully erosion phases this study investigates the development and age of two old permanent gullies that are conserved in the ancient meerdaal forest in central belgium the development history of both gullies is very similar in the first gully archaeological evidence was found indicating an erosion phase during roman times followed by a partial infilling of the gully in the second gully radiocarbon dating provided evidence of the same roman activity phase cal yr 46 bc ad 78 but also of an earlier incision phase during the middle bronze age cal yr 1743 1602 1568 1533 bc also here the erosion phase was followed by a partial infilling this limited infilling indicates that the catchment of the gullies was reforested quite rapidly hereby cutting off all runoff and sediment production this has led to a unique situation in the meerdaal forest with the conservation of about 43 similar large gullies in an area of about 17 km 2 this area has a high geovalue as the studied gullies are among the oldest and best conserved gullies in northwestern europe

geographical variability of the first baroclinic rossby radius of deformation global 1 83 18 climatologies of the first baroclinic gravity wave phase speed c1 and the rossby radius of deformation l1 are computed from climatological average temperature and salinity profiles these new atlases are compared with previously published 5 83 58 coarse resolution maps of l1 for the northern hemisphere and the south atlantic and with a 1 83 18 fine resolution map of c1 for the tropical pacific it is concluded that the methods used in these earlier estimates yield values that are biased systematically low by 5 15 owing to seemingly minor computational errors geographical variations in the new high resolution maps of c1 and l1 are discussed in terms of a wkb approximation that elucidates the effects of earth rotation stratification and water depth on these quantities it is shown that the effects of temporal variations of the stratification can be neglected in the estimation of c1 and l1 at any particular location in the world ocean this is rationalized from consideration of the wkb approximation

climatic and environmental changes at southeastern coast of lake biwa over past 3000 years inferred from borehole temperature data abstract in order to infer past climatic change in central japan we measured temperatures in a borehole at the karasuma site on the southeastern coast of lake biwa and reconstructed sediment surface temperature history during the last 3000 years the reconstructed temperature history shows apparent medieval warm period little ice age and contemporary temperature warming however the large amplitude of the temperature changes up to 4 5 k cannot be explained by past climatic change only suggesting that there was some other cause of the larger amplitude temperature changes the onsets of temperature decrease in the late 12th century a d and temperature increase in the mid 17th century a d appear to coincide with occurrences of two destructive earthquakes 1185 and 1662 a d that caused water level changes of lake biwa it suggests that the reconstructed sediment surface temperature history reflects the environmental change due to tectonically induced water level changes of the lake if the annual mean of the ground surface temperature was higher than that of the bottom water temperature in a shallow part of the lake which is consistent with the present day data the large amplitude of the sediment surface temperature change may be attributed to a combined effect of past climatic and environmental changes thus we suggest that the borehole temperature at the karasuma site preserves information not only on past climate changes but also on environmental changes due to tectonically induced water level changes

holocene floodplain sediment storage and hillslope erosion within the rhine catchment the response of fluvial systems to land use and climate change varies depending on catchment size while forcing response mechanisms of small catchments are reasonably well understood the response of larger drainage basins is less clear in particular the impact of land use and climate change on the rhine system is poorly understood because of the catchment size 185 000 km 2 and the long history of human cultivation which started approximately 7500 years ago a sediment budget is calculated to specify the amount of alluvial sediment that was deposited during the holocene and to estimate long term soil erosion rates the results suggest that 599 14 10 9 t of holocene alluvial sediment is stored in the non alpine part of the rhine catchment south and central germany eastern france the netherlands about 50 of holocene alluvial sediment is deposited along the trunk valley and the delta upper rhine lower rhine coastal plain while the rest is stored along the tributary valleys the floodplain sediment storage corresponds to a mean erosion rate of 0 559 0 16 t ha per yr 38 59 10 7 mm kyr across the rhine catchment outside the alps this holocene averaged estimate amounts for sediments that were delivered to the channel network and is at the lower limit of erosion rates from other studies of different methodology

sensitivity of west and central european river systems to environmental changes during the holocene a review abstract sediment deposition in floodplains is an essential part of the sediment dynamics of a catchment these sediment dynamics can vary largely on a holocene time scale under the influence of driving forces such as land use and climatic variations in this paper we review the holocene floodplain sediment deposition history of rivers in west and central europe with special attention to the influence of climate and land use variability during the early holocene preboreal to atlantic period most floodplains were rather stable with limited floodplain aggradation after this initial phase of relative stability sedimentation rates increase during the middle and late holocene with often the most important deposition phase during the last 1000 to 2000 a the start of the increase in sedimentation varies spatially with an earlier start in the west france germany then in the east poland belarus ukraine while there are also local differences between regions which are settled early e g loess regions compared to later settled regions the sedimentation history of most floodplains can be linked to the local land use history while influence of climatic variations on floodplain aggradation is often reported to be of minor importance processes related to bedload are often reported to be more influenced by climatic events relationships between the driving forces and the sediment history are mainly based on synchronicity and there is seldom proof for a direct causal relationship future research should focus on a system based approach integrating the floodplain deposition in the entire sediment dynamics which includes also erosion colluvial deposition and export main research questions that need further attention include integration of system based concepts like landscape connectivity and buffering effects and also the assessment of the individual contribution of land use changes and climatologic variations on the sediment dynamics detailed sediment budget studies combined with modeling studies can make an important contribution to the understanding of floodplain sediment dynamics

soil erosion and sediment deposition in the belgian oess belt during the holocene establishing a sediment budget for a small agricultural catchment a method to establish a holocene sediment budget for a 103 ha agricultural catchment representative for the belgian loess belt is presented soil erosion and sediment deposition were determined based on 185 coring locations and a large excavation in the valley bottom results were integrated in a gis and interpolation techniques applied to derive spatial patterns of erosion and sedimentation total soil erosion sediment deposition and sediment export were calculated and the results show that volumes are highly dependent on the interpolation technique used sediment delivery ratios between 20 and 42 are derived and are consistent with data reported in previous studies this clearly shows that the majority of the sediments produced during the holocene have been stored near their source area and have not been delivered to the downstream rivers the spatial distribution of soil erosion and sediment deposition within the catchment is strongly dependent on slope gradient and position within the catchment which suggests that since human impact began topography has been the main factor determining long term soil erosion and sedimentation

establishing sediment budgets for two small lowland agricultural catchments in the uk sediment budgets have been established for two small 4 km2 lowland agricultural catchments by using 137cs measurements sediment source fingerprinting and more traditional monitoring techniques to quantify the individual components of the budget the gross and net erosion rates for the fields on the catchment slopes were estimated using 137cs measurements within selected fields which encompassed a representative range of slope angles slope lengths and land use these estimates were extrapolated over the entire catchment using a simple topographically driven soil erosion model terrain based gis tbgis superimposed on a dem to derive catchment average gross and net erosion rates suspended sediment yields were measured at the catchment outlets and sediment source fingerprinting techniques were used to establish the relative contributions from the catchment surface subsurface tile drains and eroding channel banks to the sediment yields in channel and wetland storage were quantified using both direct measurements and 137cs measurements the sediment budgets established for the catchments highlighted the importance of subsurface tile drains as a pathway for sediment transfer accounting for ca 60 and 30 of the sediment output from the two catchments erosion from channel banks contributed ca 10 and 6 of the sediment output from the two catchments although the suspended sediment yields from these catchments were considered high by uk standards ca 90 t km 2 year 1 the sediment delivery ratios ranged between 14 and 27 indicating that a major proportion of the mobilised sediment was stored within the catchments in field and field to channel storage were shown to be of similar magnitude but storage of sediment in the channel system and associated wetlands was relatively small representing 5 of the annual suspended sediment yield

rapid development and infilling of a buried gully under cropland central belgium abstract analysis of contemporary and past gully erosion and infilling processes allowed to reconstruct the long term evolution of a permanent gully system under cropland an active and a buried gully under cropland were investigated the recent sediment deposits within the active gully adjacent to the buried gully showed that the recent gully was filling in at a mean rate of 6 4 cm a 1 in the buried gully several erosion and deposition phases could be identified and the type of deposited sediments revealed a complex infilling history charcoal pottery and brick fragments of different sizes were found at all depths of the gully infilling their age indicates that the first gully incised after the midst of the 17th century most probably in the second half of the 18th century or the early 19th century gully morphology and analogy with the processes in the recent gully indicate that the buried gully filled in rapidly overall five cycles of cut and fill occurred in 350 years or less and four cycles even within little less than a few decades indicating that gully development and infilling under cropland can be very rapid processes

the nature of small scale flooding muddy floods and retention pond sedimentation in central belgium abstract this study investigates the spatial variation of small scale flooding and muddy floods in rural areas in a medium sized study area 5516 km2 and the linkage with controlling factors a questionnaire set up in central belgium indicates that 43 of the municipalities have to deal from time to time with muddy floods generated from direct runoff from arable land and 36 with flooding of permanent streams a strong relation exists between the nature of the problem and the site in relation to topography and landuse areas suffering from muddy floods have significantly steeper cultivated slopes compared to areas suffering only from small scale flooding the high spatial and temporal frequency of small scale flooding and muddy floods results in emotional and significant economic damage to private households as a control measure more than 100 retention ponds have been constructed with 50 more to be built in the near future the mean cost for the construction of a retention pond amounts to 380 000 euro these retention ponds store large quantities of sediment from runoff events and must thus be dredged regularly with costs of the order of 1 5 million euro yearly the dredged sediment volumes can be used to assess and predict sediment yield for these drainage basins values vary between 0 19 and 6 m3 ha 1 year 1 for basins ranging from 25 to 5000 ha

age and source of colluvial sediments at vaihingen enz germany abstract colluvial sediments accumulated on the lower slopes of a ridge as a result of past and present soil erosion were dated by optical 14 c and archaeological methods this allowed us to reconstruct the depositional history of the colluvium and also to identify temporary sedimentary sinks in its transportational pathway a cascade model of colluvium formation is developed colluvial sediments resulting from early soil erosion in the neolithic to iron age periods were mainly deposited on the upper slopes significant deposition on the lower slope occurred for the first time during the iron age and roman period since then deposition rates have increased because of more intensive land use

establishing fine grained sediment budgets for the pang and lambourn locar catchments uk summary an integrated approach to data collection combining the use of 137cs measurements sediment source fingerprinting bed sediment surveys and conventional river monitoring has been successfully employed to establish the fine grained sediment budgets of two lowland groundwater fed catchments in the uk gross surface erosion is higher on cultivated land pang 55 263 t yr 1 or 507 t km 2 yr 1 lambourn 79 997 t yr 1 or 437 t km 2 yr 1 than on pasture pang 1960 t yr 1 or 140 t km 2 yr 1 lambourn 1425 t yr 1 or 95 t km 2 yr 1 in both study areas and a substantial proportion of the mobilized sediment is sequestered within the fields pang 28 058 t yr 1 or 228 t km 2 yr 1 lambourn 55 575 t yr 1 or 281 t km 2 yr 1 and between the individual fields and the river channel network pang 28 672 t yr 1 or 233 t km 2 yr 1 lambourn 24 782 t yr 1 or 125 t km 2 yr 1 the sediment contribution from banks and subsurface sources is relatively low and typically ca 5 t yr 1 in the pang and ca 11 t yr 1 in the lambourn representing only about 1 of the suspended sediment output from each study catchment the mean level of fine grained sediment storage in the main channel system is equivalent to 38 pang and 21 lambourn of the respective mean annual suspended sediment yields of the two catchments the estimated sediment delivery ratio for both study catchments is ca 1

historical analysis indicates seepage control on initiation of meandering in analytical and numerical models of river meandering initiation of meandering typically occurs uniformly along the streamwise coordinate in the channel based on a historical analysis of the nierskanaal here we show how and under which circumstances meandering has initiated in isolated sections of a channel the nierskanaal was constructed by the end of the 18th century as a straight channel between the river niers and the river meuse the purpose of this measure was to reduce flood risk in the downstream reaches of the river niers the banks on the dutch part of the channel were left unprotected and developed into a morphodynamically active channel featuring a meandering planform and valley incision the planform development and incision process is analysed using topographic maps and airborne lidar data meandering initiated in three sections of the channel where the channel sinuosity developed asynchronously sedimentary successions in the study area show layers of iron oxide indicating groundwater seepage from aeolian river dunes and river deposits located nearby only at the spots where meandering has initiated iron oxide is found close to the surface level this provides a clue that seepage triggered bank erosion by increasing moisture content of the banks the isolated meandering sections expanded in the longitudinal direction valley incision has developed in the first decades after the construction of the channel and diminished after a gravel layer was reached gravel was deposited in the downstream half of the channel bed acting as an armouring layer the spatial variation in meandering behaviour as observed in the nierskanaal justifies efforts to implement the influence of floodplain heterogeneity and the effect of seepage on bank erosion in meander models

the temporal and spatial quantification of holocene sediment dynamics in a meso scale catchment in northern bavaria germany the aufsess river catchment 97 km2 in northern bavaria germany is studied to establish a holocene sediment budget and to investigate the sediment dynamics since the early times of farming in the third millennium bce the temporal characterization of the sediment dynamics is based on an intensive dating program with 73 osl and 14 14c ages to estimate soil erosion and deposition colluvial and alluvial archives are investigated in the field by piling and trenching supported by laboratory analyses the sediment budget shows that 58 of these sediments are stored as colluvium in on and foot slope positions 9 are stored as alluvium in the floodplains and 33 are exported from the aufsess river catchment colluviation starts in the end neolithic c 3100 bce while first indicators of soil erosion derived alluviation is recorded c 2 3 ka later the pattern of sedimentation rates also displays differences between the colluvial and alluvial system with a distinct increase in the middle ages c 1000 c

physical and biogeochemical properties in landfast sea ice barrow alaska insights on brine and gas dynamics across seasons 1 the impacts of the seasonal evolution of sea ice physical properties on ice ocean biogeochemical exchanges were investigated in landfast ice at barrow alaska from january through june 2009 three stages of brine dynamics across the annual cycle have been identified based on brine salinity brine volume fraction and porous medium rayleigh number ra these are sea ice bottom layer convection full depth convection and brine stratification we further discuss the impact of brine dynamics on biogeochemical compounds in sea ice stable isotopes of water d 18o nutrients no3 po43 nh4 microalgae chlorophyll a and inert gas argon in general full depth convection events favor exchanges between sea ice and seawater while brine stratification limits these exchanges however argon responds differently to brine dynamics than the other biogeochemical compounds analyzed in this study this contrast is attributed to the impact of bubble nucleation on inert gas transport compared to the other biogeochemical compounds we present a scenario for argon bubble formation and evolution in sea ice and suggest that a brine volume fraction approaching 7 5 10 is required for inert gas bubbles to escape from sea ice to the atmosphere

heavy metal contamination in overbank sediments of the geul river east belgium its relation to former pb zn mining activities overbank sediments of the geul river east belgium are highly contaminated by the heavy metals pb zn and cd due to former pb zn mining activities in the drainage basin geochemical variations in vertical overbank sediment profiles sampled 1 km north of the mine tailings of plombieres allow metal fluxes back to the 17th century to be reconstructed the vertical profiles are subdivided into three major units corresponding to different industrial periods based on sedimentological criteria as well as on the distribution of contaminants alluvial sediments with the highest heavy metal concentrations correspond to the major period of mining activity of the 19th century the fact that zn mining at the la calamine open mine started before large scale mining of the pbs zns subsurface exploitations is reflected in the vertical profiles by an increase in zn content before a marked increase in pb and cu the regional extent of contamination in the alluvial deposits was evaluated on the basis of the geochemical analysis of sediments at depths of the 0 20 cm and 80 100 cm most of the upper samples are extremely contaminated significant local variations in heavy metal concentration in the lower samples are interpreted in terms of which overbank sediment horizon has been sampled at a depth of 80 100 cm this indicates that blind sampling of overbank sediments to characterize the degree of contamination in shallow boreholes can give very erratic results

ice melt influence on summertime net community production along the western antarctic peninsula the western antarctic peninsula wap is a highly productive marine environment that is undergoing rapid change with consequences for productivity and total ecosystem carbon cycling we present continuous underway o2 ar estimates of net community production ncpo2ar in austral summer 2012 2013 and 2014 at sub kilometer horizontal resolution within the palmer long term ecological research pal lter grid region of the wap substantial spatial variability is observed with ncpo2ar ranging from 0 to 790 mmol o2 m 2 d 1 and considerable interannual variability with mean values in the grid region of 54 4 48 5 44 6 40 5 and 85 6 75 9 mmol o2 m 2 d 1 in 2012 2013 and 2014 respectively based on a strong correlation r2 0 83 between residence time integrated ncpo2ar and ncpdic derived from seasonal dic drawdown we find the observed ncpo2ar spatial and interannual variability to be consistent with the december january ncpdic magnitude seeking to explain the mechanistic drivers of ncp in the wap we observe a linear relationship between ncpo2ar and meteoric water content derived from 18o and salinity this correlation may be due to fe supply from glacial melt and or strengthening of stratification and relief of light limitation elevated surface fe availability as indicated by fv fm and measurements of surface water dissolved fe and mn a rough proxy for recent potential fe availability and shallower more stable mixed layers are present where meteoric water and or sea ice melt is high near the coast light limitation is evident in the wap when mixed layer depths are greater than 40 m additionally we document hotspots of ncp associated with submarine canyons along the wap while it is difficult to predict how the physical biological system might evolve under changing climatic conditions it is evident that ncp and potentially carbon flux out of the mixed layer along the wap will be sensitive to shifts in meltwater input and timing

a cellular model of holocene upland river basin and alluvial fan evolution coulthard t j macklin m g kirkby m j 2002 a cellular model of holocene upland river basin and alluvial fan evolution earth surface processes and landforms 27 3 269 288

alluvial and colluvial sediment storage in the geul river catchment the netherlands combining field and modelling data to construct a late holocene sediment budget abstract we used a combined approach of a two dimensional erosion and hillslope sediment delivery model watem sedem and detailed geomorphological reconstructions to quantify the different components in a sediment budget for the geul river catchment southern netherlands since the high middle ages hillslope erosion and colluvium deposition were calculated using the model while floodplain storage was estimated using field data our results show that more than 80 of the total sediment production in the catchment has been stored as colluvium mostly generated by hillslope erosion while almost 13 is stored in the floodplain since the high middle ages this situation resembles a capacity limited system model results for the period prior to the high middle ages with a nearly completely forested catchment show that far less sediment was generated and that most of the sediments were directly transported to the main river valleys or out of the catchment a supply limited system geomorphological analysis of a large alluvial fan shows the sensitivity of the study area to changes in the percentage of arable land our combined field data modeling study presents an elegant method to calculate a catchment sediment budget for a longer period and is able to identify and quantify the most important sediment storage elements furthermore it provides a valuable tool to calculate a sediment budget while only limited dated fluvial sediment sequences are available

mechanisms controlling the global oceanic distribution of the inert gases argon nitrogen and neon 1 dissolved inert gas measurements in the ocean yield important information about processes that occur during water mass formation we present argon nitrogen and neon data from the subtropical and subpolar north pacific and the subtropical north atlantic all three gases were supersaturated at the surface in the deep ocean ar and n2 were undersaturated while ne remained supersaturated all the data fell within the range predicted by a quasi steady state mixed layer model that allows only temperature change and diffusive and bubble mediated gas exchange this result suggests that these three processes are the first order controls on the global oceanic distribution of inert gas saturations

land use and climatic impacts on the rhine system rheinlucifs quantifying sediment fluxes and human impact with available data abstract the rheinlucif project investigates the effects of land use and climatic impacts on sediment fluxes in the river rhine catchment among the world s large rivers the rhine system has been particularly affected by land use changes for 7500 years resulting in its transformation to an entirely man controlled environment geomorphologically this transformation is performed by largely man induced sediment fluxes since the mid holocene as the large scale of the rhine catchment inhibits a renewed recording of stratigraphic records the main goal is to synthesize quantitative data on sediment flux climatic and human impacts from already available data from various fields of earth surface and social sciences particularly history and archaeology this paper presents the first steps and results of methodological groundwork exploring how to derive sediment budgets from available spatially distributed data soil maps geological maps dems furthermore a new basically statistical approach utilising archaeological data is outlined this approach provides time series of quantified human impact i e information on population densities and open land woodland ratios the first results derived from four different sediment budget approaches are helpful in order to assess the quality of available data for budget calculation purposes although some estimates on erosion and alluvial deposition seem to broadly agree a considerable disparity of holocene erosion and colluviation values occurs when these values are compared to the outcome of an independently recorded soil mapping campaign in a pilot area however in general the results suggest that all applied approaches chiefly require an improved estimation of sediment storage on the one hand this accounts for the need of more precise information on holocene floodplain deposits on the other hand as the larger portion of man induced sediments still resides in the sloping parts of catchments realistic estimates on man induced colluvial deposition on slopes are essential apart from budgeting issues all data on holocene erosion and sedimentation in the rhine catchment lacked a sufficient dating control therefore further investigations on fluxes between budget components necessitate additional datings quantified data on human impact is indispensable to the modelling of sediment fluxes because human impact is deemed to be the major driving force of sediment production and re distribution although the archaeological approach was developed and tested by utilising well documented data about the neolithic era the promising statistical evaluation suggests that this method can be applied to even less well documented proto prehistoric and historic periods

the freshwater system west of the antarctic peninsula spatial and temporal changes climate change west of the antarctic peninsula is the most rapid of anywhere in the southern hemisphere with associated changes in the rates and distributions of freshwater inputs to the ocean here results from the firstcomprehensivesurveyofoxygenisotopesinseawaterinthisregionareusedtoquantifyspatialpatternsof meteoric water glacial discharge and precipitation separately from sea ice melt high levels of meteoric water are found close to the coast due to orographic effects on precipitation and strong glacial discharge concentrations decrease offshore driving significant southward geostrophic flows up to 30 cm s 21 these produce high meteoric water concentrations at the southern end of the sampling grid where collapse of the wilkins ice shelf may also have contributed sea ice melt concentrations are lower than meteoric water and patchier because of the mobile nature of the sea ice itself nonetheless net sea ice production in the northern part of the sampling grid is inferred combined with net sea ice melt in the south this indicates an overall southwardicemotion thesurveyiscontextualizedtemporallyusingadecade longseriesofisotopedatafrom a coastal antarctic peninsula site this shows a temporal decline in meteoric water in the upper ocean contrary to expectations based on increasing precipitation and accelerating deglaciation this is driven by the increasingoccurrenceofdeeperwintermixedlayersandhaspotentialimplications forconcentrations oftrace metals supplied to the euphotic zone by glacial discharge as the regional freshwater system evolves the continuing isotope monitoring described here will elucidate the ongoing impacts on climate and the ecosystem

ocean acidification and calcium carbonate saturation states in the coastal zone of the west antarctic peninsula the polar oceans are particularly vulnerable to ocean acidification the lowering of seawater ph and carbonate mineral saturation states due to uptake of atmospheric carbon dioxide co2 high spatial variability in surface water ph and saturation states for two biologically important calcium carbonate minerals calcite and aragonite was observed in ryder bay in the coastal sea ice zone of the west antarctic peninsula glacial meltwater and melting sea ice stratified the water column and facilitated the development of large phytoplankton blooms and subsequent strong uptake of atmospheric co2 of up to 55 mmol m 2 day 1 during austral summer concurrent high ph 8 48 and calcium carbonate mineral supersaturation aragonite 3 1 occurred in the meltwater influenced surface ocean biologically induced increases in calcium carbonate mineral saturation states counteracted any effects of carbonate ion dilution accumulation of co2 through remineralisation of additional organic matter from productive coastal waters lowered the ph 7 84 and caused deep water corrosivity aragonite 0 9 in regions impacted by circumpolar deep water episodic mixing events enabled co2 rich subsurface water to become entrained into the surface and eroded seasonal stratification to lower surface water ph 8 21 and saturation states aragonite 1 8 relative to all surface waters across ryder bay uptake of atmospheric co2 of 28 mmol m 2 day 1 in regions of vertical mixing may enhance the susceptibility of the surface layer to future ocean acidification in dynamic coastal environments spatially resolved studies are essential to elucidate the natural variability in carbonate chemistry in order to better understand and predict carbon cycling and the response of marine organisms to future ocean acidification in the antarctic coastal zone

sediment yield and storage variations in the negron river catchment south western parisian basin france during the holocene period in the negron river catchment area 162 km2 surface sediment stores are composed of periglacial calcareous greze 5 106 t and loess 21 106 t and holocene alluvium 12 6 106 t peat 0 6 106 t and colluvium 18 5 106 t seventy five per cent of the holocene sediments is stored along the thalwegs present net sediment yield calculated from solid discharge at the negron outlet is low 0 6 t km 2 a 1 due to the dominance of carbonate rocks in the catchment mean sediment yield during the holocene period is 7 0 t km 2 a 1 from alluvium stores and 7 6 t km 2 a 1 from colluvium stores thus the gross sediment yield during the holocene period is about 18 7 t km 2 a 1 and the sediment delivery ratio 3 per cent the yield considerably varies from one sub basin to another 3 9 to 24 5 t km 2 a 1 according to lithology about 25 per cent and 50 per cent of initial stores of periglacial greze and loess respectively were reworked during the holocene period sediment yield has increased by a factor of 6 in the last 1000 years due to the development of agriculture the very high rate of sediment storage on the slope during that period 88 per cent of the yield can be accounted for by the formation of cultivation steps rideaux it is predicted that the current destruction of these steps will result in a sediment wave reaching the valley floors in the coming decades subboreal and subatlantic sediments and pollen assemblages in the taligny marsh where one third of the alluvium is stored show the predominant influence of human activity during these periods in the negron catchment copyright 2002 john wiley sons ltd

the formation of alluvial fans and young floodplain deposits in the lieser catchment eifel mountains western german uplands a study of soil erosion budgeting this study deals with the exploration and spatiotemporal quantification of the young holocene nearly skeleton free floodplain sediments of the lieser river a tributary of the mosel river in the eifel mts the deposits are primarily a consequence of anthropogenic triggered soil erosion in the catchment to observe the phenomenon of corresponding soil erosion on multiple levels two small alluvial fans of tributary catchments were investigated for comparison one location in the neighboring salm valley was described the results were compared with those of other streams with extensive fieldwork more than 100 drillings and pits were made at 12 locations for dating the sediments osl dating 14c dating of organic contents and archaeological artifacts were used in the floodplains of the lieser and its tributaries 35 1 106 t of overbank fines are stored to achieve this an average soil erosion of 61 4 mm in the whole catchment would have been necessary about 28 of young floodplain sediments in upper a

a possible solar pacemaker for holocene fluctuations of a salt marsh in southern italy abstract this study is aimed at verifying the possible influence of solar activity on the coastal vegetation development in the tavoliere plain south adriatic region italy between 6350 and 4000 cal bp when regular fluctuations of halophilic vegetation are recorded by pollen a wavelet analysis applied to the percentage values of glasswort vegetation is consistent with periodicities of solar activity and other palaeoenvironmental and palaeoclimate proxies in the literature a comparison of salt marsh pollen indicators salicornia type and ruppia maritima with the 10be dataset from the greenland ice core gisp2 on the basis of their independent chronologies reveals a strong visual correlation indicating that the minima of salt marsh percentages match minima in the 10be curve corresponding to solar activity maxima associated with warm and arid phases at the middle latitudes the tavoliere salt marsh appears to have contracted during the arid warm phases associated to maxima of solar activity and to have expanded during the wet cold phases of solar minima this coastal area characterized by a very flat topography and arid climate appears to have been very sensitive to even minor hydrological and climate changes changes of solar activity determining extensive environmental transformations were also possibly responsible for the abandonment of the human coastal settlements of one of the most important neolithic archaeological districts of italy

holocene floodplain deposition and scale effects in a typical european upland catchment a case study from the ambleve catchment ardennes belgium this study quantifies holocene alluvial sediment deposition in the belgian ambleve catchment 1080 km2 situated in the ardennes uplands an extended coring data set is used for a quantitative description and a quantification of the alluvial depositions the floodplains fall into three main types the upper and lower floodplains and the steep reaches total holocene alluvial sediment deposition amounts to 32 tg or 0 029 tg km2 dating of sediments using iron slag as tracer shows that on average 42 of contemporary storage was accumulated during the last 600 years radiocarbon dating of fluvial deposits at eight sites in the catchment confirms that the majority of the sediment is relatively recent the increased sedimentation rates for this period are related to anthropogenic land use possibly enhanced by climatic variations a fluvial sediment budget was constructed for this 600 yr time period and shows that export from the catchment has about the same importance as storage in the floodplains while la

sediment flux to basins causes controls and consequences there is an increasing trend in the earth sciences towards the integration of many subdisciplines the sedimendatry basin is a fundamental focal point of many studies which as a consequence often neglects the complimentary drainage basin or catchment sedimentary basins provide a record of earth history reflecting the geographical lithological oceanographic and ecological development through the rock record drainage basins in comparison record ephemeral landscape evolution where topography is eroded and provides the flux of sediment to the basin the basin fill reflects the sediment flux from the hinterland and provides evidence of the dynamic geomorphic processes in context the drainage system and sedimentary basin can be regarded as a production line with sedimentary record giving valuable insight into long term landscape evolution and geomorphological processes illuminating the evolution of sedimentary basins this volume assesses the current position of understanding sediment supply to basins with the integration of the many sub disciplines in the earth sciences it documents a mix of hinterland and sedimentary basin studies with a gradation from orogenic belts to the deep marine the authors represent a wide spectrum of earth scientist with leaders in the science providing review papers and new directive papers in their field of specialization

human and climate impact on catchment development during the holocene geul river the netherlands interest in the holocene development of small to medium sized river catchments in western and central europe in relation to changes in land use and climate has increased over the past years in this study we reconstruct the holocene landscape development and fluvial dynamics of the geul river the netherlands and the main forcing mechanisms of environmental change field studies were carried out and we used osl and 14c dating methods to reconstruct the holocene valley development our study shows that 2 periods of deforestation during the roman period and the high middle ages led to severe soil erosion and increased floodplain sedimentation in the catchment of the geul river possibly combined with periods of increased wetness during the high middle ages alluvial fans have been active since the roman deforestation phase our results show that the geul catchment is highly sensitive to changes in land use

coastal southern ocean a strong anthropogenic co2 sink 1 large scale estimates of the southern ocean co2 sink do not adequately resolve the fluxes associated with antarctic continental shelves using a mechanistic three dimensional biogeochemical model of the ross sea we show that antarctic shelf waters are a strong sink for co2 due to high biological productivity intense winds high ventilation rates and extensive winter sea ice cover net primary production npp in these waters is 0 055 pg c yr 1 some of this carbon sinks to depth driving an influx of co2 of 20 50 g c m 2 yr 1 although currently unaccounted for the total atmospheric co2 sink on the ross sea continental shelf of 0 013 pg c yr 1 is equivalent to 27 of the most recent estimate of the co2 sink for the entire southern ocean given these results these and other highly productive waters around the antarctic continent need to be included in future budgets of anthropogenic co2