ancient runoff farming and soil aggradation in terraced wadi fields negev israel obliteration of sedimentary strata by ants scorpions and humans abstract ancient terraced fields in ephemeral stream valleys in the negev desert enabled farming based on runoff water from local rainfall the runoff was captured by stone terrace walls which were built across suitable wadis in various archaeological periods runoff floods added not only water to the fields but also fine sediment however alluvial stratification is usually absent in such terraced wadi fields why we addressed this question at the rural archaeological site of horvat haluqim in the central negev highlands our geoarchaeological excavations in area 3 of terraced field 12 revealed the existence of laminar alluvial stratification but only in the upper 5 cm micromorphology showed a gradual decline in the preservation of laminae with depth radiocarbon dating showed that the upper 50 cm of the terrace soil accumulated during the past 1300 years therefore the average aggradation rate seems about 0 4 mm year similar to modern sedimentation measurements we found evidence for bioturbation particularly by ants and scorpions in the terraced wadi fields at horvat haluqim scorpions evict the soil crumbs excavated from the subsoil on one side of the crescent shaped entrance to their burrows ants on the other hand place the excavated soil crumbs all around the entrance to their underground nest besides bioturbation human soil disturbance by farming is far more destructive to alluvial stratification hoeing and ploughing tillage can erase alluvial laminae from the surface to a depth of about 10 cm in one farming season clear evidence of ancient farming activities in area 3 was found in darker soil layers from a depth of 45 cm 92 cm laminar alluvial strata have not survived in these layers micromorphology revealed fine charcoal bone and pottery fragments interpreted as kitchen household refuse added as fertilizer to the aggrading soil surface in addition non burned dung fragments and non charred spherulites were found indicating also the use of animal dung as manure darker soil layers have a lower bulk density and a high porosity with an extremely large amount of fine pores probably ancient root channels of barley or wheat though runoff flows kept adding laminated alluvial layers to the aggrading terraced wadi fields the fine laminae initial facies did not endure the tooth of time they were gradually obliterated by bioturbation and or rapidly erased by human farming activities tillage and manuring so that laminae are non existent in the ultimate facies of the aggrading sediment soil in agricultural terraced wadi fields

soil seal development under simulated rainfall structural physical and hydrological dynamics this study delivers new insights into rainfall induced seal formation through a novel approach in the use of x ray computed tomography ct up to now seal and crust thickness have been directly quantified mainly through visual examination of sealed crusted surfaces and there has been no quantitative method to estimate this important property x ray ct images were quantitatively analysed to derive formal measures of seal and crust thickness a factorial experiment was established in the laboratory using open topped microcosms packed with soil the factors investigated were soil type three soils silty clay loam zcl sandy silt loam szl sandy loam sl and rainfall duration 2 14 minutes surface seal formation was induced by applying artificial rainfall events characterised by variable duration but constant kinetic energy intensity and raindrop size distribution soil porosities derived from ct scans were used to quantify the thickness of the rainfall induced surface seals and reveal temporal seal micro morphological variations with increasing rainfall duration in addition the water repellency and infiltration dynamics of the developing seals were investigated by measuring water drop penetration time wdpt and unsaturated hydraulic conductivity kun the range of seal thicknesses detected varied from 0 6 5 4 mm soil textural characteristics and om content played a central role in the development of rainfall induced seals with coarser soil particles and lower om content resulting in thicker seals two different trends in soil porosity vs depth were identified i for sl soil porosity was lowest at the immediate soil surface it then increased constantly with depth till the median porosity of undisturbed soil was equalled ii for zcl and sl the highest reduction in porosity as compared to the median porosity of undisturbed soil was observed in a well defined zone of maximum porosity reduction c 0 24 0 48 mm below the soil surface this contrasting behaviour was related to different dynamics and processes of seal formation which depended on the soil properties the impact of rainfall induced surface sealing on the hydrological behaviour of soil as represented by wdtp and kun was rapid and substantial an average 60 reduction in kun occurred for all soils between 2 and 9 minutes rainfall and water repellent surfaces were identified for szl and zcl this highlights that the condition of the immediate surface of agricultural soils involving rainfall induced structural seals has a strong impact in the overall ability of soil to function as water reservoir

meltwater floods into the black and caspian seas during heinrich stadial 1 abstract deglaciation of the eurasian ice sheet dispensed vast amounts of meltwater laden with red brown clay into black and caspian sea s freshwater lakes between 16 350 and 15 400 calendar years bp the arriving sediment had a mineral composition and strontium neodymium isotope signatures 87sr 86sr and end consistent with the crystalline bedrock that lay beneath the ice sheet as opposed to sources from landscapes crossed by the rivers that carried meltwater to the lakes the magnitude and rapidity of the shifts of 87sr 86sr and 18o in shells of ostracods and mollusks an eight fold increase in sediment accumulation rate and a plunge of 1250 14c years in the radiocarbon reservoir age indicate a volume of meltwater sufficient to have replaced most or all of the pre existing lake water if the release of 25 000 km3 of water from the caspian into the black sea s new euxine lake was abrupt by judging the magnitude of erosion in the floor of the manych strait spillway this event qualifies as a megaflood deeply scoured furrows channel floor bars and swaths of mounds 5 20 km in length and 5 20 m in height are reminiscent of scabland landscapes the meltwater is coincident with heinrich stadial 1 when the alpine and eurasian ice sheets re advanced and temperatures of the black sea s lake surface remained cold sand grains within the red brown clay indicate they were transported by lake surface ice

a high resolution micromorphological record of changing landscapes and climates on the western loess plateau of china during oxygen isotope stage 5 abstract the micromorphological characteristics of a continuous set of block samples from 24 38 m depth in a well section on jiuzhoutai mountain lanzhou china are described the shape of the magnetic susceptibility curve together with previously published radiocarbon luminescence and geomagnetic dates indicates that this sample set encompasses the whole of the last interglacial s1 palaeosol complex and extends into the overlying and underlying loess l1 and l2 units seven pedosedimentary units are recognised on the basis of trends in the bulk properties and the key micromorphological indicators excrements textural concentrations shell fragments and calcite and gypsum features high rates of loess deposition with significant cryogenic activity gypsum precipitation and only weak bioturbation characterised oxygen isotope stage ois 6 and ois 4 at lanzhou depositional rates were moderately high in ois 5d and 5b with slightly higher bioturbation and no significant cryogenesis or gypsum precipitation ois 5e 5c and 5a were marked by low rates of accretion more extensive bioturbation and limited leaching this reconstruction reflects the pedosedimentary responses to fluctuating dominances of monsoonal controls during this period of global climatic change comparison of earlier micromorphological results from sites to west and east of lanzhou along a dry to humid climatic gradient indicate a clear regional pattern with reduced loess accumulation rates and enhanced bioturbation and leaching in the humid east tianshui and xian clay translocation occurred only in ois 5e at xian the warmest and most humid site on the transect

lateglacial and holocene sea level changes in semi enclosed seas of north eurasia examples from the contrasting black and white seas abstract a comparison of the black and white seas which differ in their tectonic glacial and climatic history but which share a strong dependence upon limited water exchange with the world ocean represents an opportunity for the identification of major factors controlling sea level changes during the lateglacial and holocene and for the correlation of these changes existing data were critically analyzed and compared with the results of geological geomorphological and palaeohydrological studies obtained by the present authors during the past two decades we conclude that glacioeustatic processes played a major role in relative sea level changes on most coasts of both areas however along several coastlines other factors overwhelm glacioeustasy during some time intervals in the black sea water level rose from its minimum position 100 120 m at 18 17 ka bp to 20 30 m at nearly 9 ka bp in the white sea the decreasing trend in relative sea level is well illustrated on the kola peninsula and in karelia subject to glacioisostatic emergence a drastic sea level fall from 15 to 25 m occurred with the drainage of glacial lakes in the eastern white sea 12 5 9 5 ka bp the black and white sea histories changed drastically in the early holocene or in the beginning of the middle holocene 9 5 7 5 ka bp due to the intrusion of water from the mediterranean and the barents seas respectively during this period the white sea developed under the strong influence of the formation of ice shelves and dead ice blocks retreating glaciers as well as of glacioisostatic and related processes the black sea history however was determined by water exchange with the mediterranean via the shallow dardanelles and bosporus straits outflow from the black sea 10 9 5 ka bp and inflow from 9 7 5 ka bp according to various data and partially by river discharge variations caused by climatic changes on the russian plain the hypothesis of a catastrophic sea level rise from 120 150 to 15 20 m nearly 7550 calendar years bp is not supported by our data water intrusion from the mediterranean was fast but not catastrophic in the black sea periods of high sea levels after the intrusion of mediterranean waters are dated from four sedimentary complexes vityazevian kalamitian dzhemetian and nymphaean from nearly 7 5 7 6 5 5 4 5 and 2 2 1 7 ka bp respectively a fluctuating pattern of sea level change was established in the white sea after the drainage of proglacial lakes and intrusion of ocean waters at the end of the early holocene nearly 8 5 8 2 ka bp major periods of sea level rise in the white sea are dated from the late boreal early atlantic 8 5 7 5 ka bp late atlantic 6 5 5 2 ka bp middle subboreal 4 5 4 ka bp and middle subatlantic 1 8 1 5 ka bp fluctuations of relative sea level during the middle and late holocene were possibly on the order of several meters from 2 3 to 2 3 m in the black sea and from 3 5 to 2 3 m in the white sea lower estimates of regressive stages are principally derived from archaeological data on ancient settlements in tectonically submerging deltaic areas and cannot be regarded as reliable palaeohydrological analysis does not indicate that intensive 15 25 m or greater sea level fluctuations were present in the black sea or in the white sea during the middle and late holocene instead such analysis provides independent evidence to support the argument that significant differences in water level between the black sea and the mediterranean could not be maintained for an extended period of time

the holocene black sea reconnection to the mediterranean sea new insights from the northeastern caucasian shelf abstract recent findings about the evolution of palaeogeographic conditions of the black sea during the holocene have significantly improved our understanding of the profound environmental changes that took place around 9 ka ago when the neoeuxinian lake reconnected to the global ocean in contrast to the western and southeastern regions where numerous studies have been recently performed the northeast region remains relatively under investigated we carried out the first multi proxy continuous study of a sediment core ak 2575 from the northeastern black sea shelf that includes benthic calcareous fossils ostracods molluscs and foraminifers dinoflagellate cysts dinocysts and sedimentology thus providing reconstructions of surface and bottom water conditions the age model of the core is based on 10 ams 14 c dates calibrated ages are used throughout the manuscript the first appearance of mediterranean elements is documented at 9 6 cal ka bp our data provide evidence of sustained cohabitation of benthic species of caspian and mediterranean origins represented by different ontogenetic stages from at least 7 8 or even 8 8 to 6 7 cal ka bp with the gradual disappearance of brackish species suggesting a gradual increase in salinity and most likely a change in the salt composition dinocyst assemblages show species succession that is coherent across the black sea basin with brackish taxa dominating until 8 5 cal ka bp and being slowly replaced by euryhaline species the occurrences of authigenic gypsum crystals especially abundant at 7 4 and 6 5 cal ka bp suggest the temporal appearance of hydrogen sulphide at the shelf edge which during certain periods appears to reduce the abundance of benthic fauna

geochemical variation in microstructural shell layers of the southern quahog mercenaria campechiensis implications for reconstructing seasonality abstract shells of the northern and southern quahogs mercenaria mercenaria and mercenaria campechiensis respectively from paleontological and archaeological deposits have been used to reconstruct climate environmental conditions and ecological relationships seasonal fluctuations in temperature and salinity are recorded in shell carbonate as variations in 18 o and 13 c values and sr ca ratios however these environmental proxies have not yet been calibrated for m campechiensis previous geochemical studies of quahog shells focused on the outer prismatic layer as an ecological archive the outer layer is often not preserved in fossil and archaeological shells moreover recent innovations in microsampling techniques allow high resolution sampling of the middle cross lamellar layer this study tests whether outer prismatic and middle cross lamellar layers record similar variations in 18 o and 13 c values and sr ca ratios in modern shells of m campechiensis and whether profiles are similar among individuals the last 2 years of shell growth from three individuals 6 7 and 9 years old collected alive near bokeelia southwest florida were microsampled for geochemical analyses 18 o varies seasonally relative to translucent summer and opaque winter growth increments variation of 18 o from outer and middle layers are identical within and among shells however the oldest individual did not preserve the most positive values represented in the two younger shells 13 c from both layers are similar within shells although the outer layer is more variable and the range of values varies somewhat among individuals sr ca ratios from the outer and middle layers within shells do not track each other well and profiles among individuals are different to evaluate whether a seasonal signal was present sr ca ratios were compared to 18 o values there was no co variation within the outer layer in any of the shells therefore this layer should be avoided when using sr ca ratios as a temperature proxy the middle layer from the 6 year old shell showed no co variation the 7 year old shell exhibited a moderate negative co variation r 2 0 55 p r 2 0 72 p 18 o and environmental interpretations made using 13 c values should be treated with caution

surface crusting in two alluvial soils of northen niger valentin c 1991 surface crusting in two alluvial soils of northen niger geoderma 48 201 222 surface crusting was studied in a sandy soil and a clay loam soil in northern niger in a subdesert to desert environment light microscopy electron microscopy image analysis and soil physics were used to study and explain different crusting processes in experimental plots two 1 m2 plots on each soil were subjected to rainfall simulation in the field under natural and tilled surface conditions this study demonstrates that kinetic energy of rainfall is the major crusting factor for the sandy soil waterlogging and subsequent slaking led to the formation of structural and depositional crusts in the tilled clay loam plot in this case a surface crust can be formed regardless of kinetic energy of the rainfall this was substantiated through double ring infiltrometer measurements in both soils infiltration was severely hindered by crusting the relationships of crusting to water and wind erosion were more ambiguous four types of crusts could be defined from this study in terms of structure genetic processes and properties it could also be demonstrated that crust control practices should take into account the texture of the original soil materials

multi temporal uav data for automatic measurement of rill and interrill erosion on loess soil the fragile landscape of the north european loess belt is prone to soil erosion due to soil properties and intense land use of the fertile region exact measurement of surface changes with high temporal and spatial resolution over large areas is necessary to quantify and understand rill and interrill erosion processes high resolution aerial imagery acquired by an unmanned aerial vehicle uav is used to automatically generate precise digital surface models dsms of high spatial resolution by applying structure from motion image processing tools during an investigation period of ten months a 600 m2 field plot is observed during four field campaigns a stable reference system is established for multi temporal comparison the overall accuracy of the dsms generated from uav images is less than 1 cm verified by comparison with terrestrial laser scanner tls data furthermore a method for automatic rill extraction and rill parameter calculation is developed which enables objective rill description with cm accuracy and resolution soil surface roughness and rill development as well as volumetric quantifications are analysed for multi temporal change detection surface changes during winter season are controlled by soil consolidation crusting and sheet erosion during rainy spring season sheet erosion and rill incision occur two thunderstorms in summer season cause dominant rill erosion erosion rills are more dominantly deepening than widening from to 2 to 4 cm depth and from 17 to 23 cm width resulting in average per rill erosion values of 0 03 and 0 07 m3 respectively an orientation dependent lateral rill shift is revealed implying rill widening in eastern direction due to dominant winds from the west volumetric quantifications indicate high erosion volumes reaching up to 121 tha 1 during the summer events highest erosion volumes are due to rill erosion rather than interrill erosion copyright 2014 john wiley sons ltd

further evidence of abrupt holocene drowning of the black sea shelf a 1999 survey of the black sea continental shelf off the north central turkish seaport of sinop using a side scan sonar small remotely operated vehicles and a series of dredge lowerings located inspected and sampled an exposed high energy paleoshoreline at a depth of 155 m radiocarbon dating of mollusk shells collected from this ancient beach revealed that the marine flooding of the black sea took place between 7460 and 6820 yr b p all ages are reported in radiocarbon years not calendar years without correction for reservoir age or dendro calibration changing it from a lacustrine to marine environment this relic surface remained in contact with the bottom waters of the black sea for a long period of time before being draped by a thin layer of sapropel mud wood samples recovered from this same location were very well preserved and yielded dates as old as 3580 yr b p q 2000 elsevier science b v all rights reserved

influence of open ocean nitrogen supply on the skeletal δ15n of modern shallow water scleractinian corals abstract the isotopic composition of skeleton bound organic nitrogen in shallow water scleractinian corals hereafter cs 15 n is an emerging tool for studying the marine nitrogen cycle in the past the cs 15 n has been shown to reflect the 15 n of nitrogen n sources to corals with most applications to date focusing on the anthropogenic terrestrial n inputs to reef environments however many coral reefs receive their primary n sources from the open ocean and the cs 15 n of these corals may provide information on past changes in the open ocean regional and global n cycle using a recently developed persulfate denitrifier based method we measured cs 15 n in modern shallow water scleractinian corals from 8 sites proximal to the open ocean at sites with low open ocean surface nitrate concentrations typical of the subtropics and tropics measured cs 15 n variation on seasonal and annual timescales is most often less than 2 in contrast a broad range in cs 15 n of 10 is measured across these sites with a strong correlation between cs 15 n and the 15 n of the deep nitrate supply to the surface waters near the reefs while cs 15 n can be affected by other n sources as well and can vary in response to local reef conditions as well as coral symbiont physiological changes this survey indicates that when considering corals proximal to the open ocean the 15 n of the subsurface nitrate supply to surface waters drives most of the cs 15 n variation across the global ocean thus cs 15 n is a promising proxy for reconstructing the open ocean n cycle in the past

compilation of geophysical geochronological and geochemical evidence indicates a rapid mediterranean derived submergence of the black sea s shelf and subsequent substantial salinification in the early holocene abstract our knowledge of rate and processes in which semi enclosed environments alternate from lacustrine to marine is commonly limited because of the paucity of specific proxies for sea level and salinity here we investigate the timing rate and key mechanisms involved in the transformation of the previously isolated black sea lake to the modern partly enclosed marine sea using a suite of geophysical geochemical and geochronological methods cores were collected in transects across shelves of ukraine romania bulgaria and turkey biogenic carbonate from these cores was analyzed for radiocarbon and strontium oxygen and carbon isotopes strontium results indicate that the submergence of the black sea shelf at 9300 calendar years bp was caused by the ingress of mediterranean water and was abrupt taking radiocarbon years are calibrated to calendar years by tuning the oxygen and carbon isotope composition of the mollusk record to that of the u th dated sofular cave stalagmites the match shows a reduction of the lake s prior high reservoir age accompanying the inflow of the mediterranean water in 900 years the salinity reached a threshold that excluded all previous black sea lacustrine fauna these results imply that any substantial postglacial submergence of the black sea shelves did not occur prior to entry of mediterranean water

constraining holocene sea surface conditions in the south western black sea using dinoflagellate cysts this paper presents two dinoflagellate cyst records from the south western shelf of the black sea a new site mar05 13 from the sakarya shelf is described and placed into context with site mar02 45 250 km distant on the thracian shelf the records provide a centennial resolution of surface water conditions in the holocene analysis of the data suggests that the surface salinity of the south western shelf increased in a gradual and progressive manner in the period 11 000 9000 cal a bp the assemblages suggest surface water salinities between 7 13 psu the initial arrival of euryhaline species 8100 cal a bp is linked to the reconnection of the black sea and marmara sea the suggested surface water changes related to the reconnection took approximately 1000 years following this initial change in assemblages a further increase in the number of euryhaline species is noted between 5000 and 4000 cal a bp this is linked to the establishment of more saline surface water conditions close to present day values the record for mar05 13 highlights the complexity of the changes in cyst assemblages during the mid holocene copyright 2012 john wiley sons ltd

multicentennial scale hydrological changes in the black sea and northern red sea during the holocene and the arctic north atlantic oscillation 1 paleoenvironmental proxy data for ocean properties eolian sediment input and continental rainfall based on high resolution analyses of sediment cores from the southwestern black sea and the northernmost gulf of aqaba were used to infer hydroclimatic changes in northern anatolia and the northern red sea region during the last 7500 years pronounced and coherent multicentennial variations in these records reveal patterns that strongly resemble modern temperature and rainfall anomalies related to the arctic oscillation north atlantic oscillation ao nao these patterns suggest a prominent role of ao nao like atmospheric variability during the holocene beyond interannual to interdecadal timescales most likely originating from solar output changes

late glacial to holocene climate and sedimentation history in the nw black sea abstract gravity cores from the continental slope in the northwestern black sea were studied using high resolution stable isotope grain size and xrf scanning data the measurements provide a 30 000 years ams 14c dated record of variations in the hydrological regime of the black sea and give insight into changing paleoenvironments in the surrounding areas stable climatic conditions during the last glacial maximum were followed by a series of meltwater pulses most likely originating from the scandinavian ice sheet between 18 000 and 15 500 yr bp 1 this meltwater input rose the level of the caspian sea to a point that caspian water could spill into the black sea via the manych depression north of the caucasian mountains high frequency oscillations in the xrf data during this period suggest a probable link to the arctic climate regime later during the bolling allerod and the early holocene prevailing high temperatures led to authigenic calcite precipitation through increased phytoplankton activity interrupted by the younger dryas and the 8200 yr bp cold event with dominant clastic sedimentation

runoff and interrill erosion on sandy soils under cultivation in the western paris basin mechanisms and an attempt at measurement measurements made on different scales such as rainfall simulations on 1 m2 and 20 m2 experimental plots and water sampling at the outlet of a watershed enable the analysis of the mechanisms of pluvial erosion and therefore the importance of runoffs and soil losses in the hilly and sandy parts of the western paris basin interrill erosion accounts for slow transfer of materials towards the lower part of plots and slopes the overland flow caused by restructuring of the surface tertiary and cenomanian soils erodes some 150 to 200 kg ha 1 during the month following sowing only a part of these deposits reach the river which carries away less than 50 kg ha 1 each month interrill erosion makes slopes still more uneven fills in valley bottoms and so paves the way to catastrophic erosion which scoops out rises in the ground and colluvial deposits in the lower part of slopes and valley bottoms copyright 2001 john wiley sons ltd

environmental controls on the stable isotopic composition of mercenaria mercenaria potential application to paleoenvironmental studies 1 we have investigated the environmental controls of seasonally resolved records of oxygen and carbon isotopes of modern mercenaria mercenaria bivalves collected live from five coastal sites along the east coast of north america seasonal profiles of 18o and 13c obtained by subsampling the incremental growth layers of aragonite were compared with in situ historical records of temperature and salinity we show that m mercenaria 18o profiles track accurately the seasonal variations of water temperature and that variations in growth rates do not affect the shell 18o values growth rates are strongly reduced or interrupted below water temperatures ranging from 8 to 10 c implying that only bivalves sampled in tropical areas track the full amplitude of seasonal variations although further measurements of water 18o and a better understanding of seasonal variations of the water 18o salinity relationships are necessary mercenaria mercenaria bivalves appear to precipitate their shell close to isotopic equilibrium whereas the amplitude of the seasonal profiles of 18o reflects variations in water temperature the annual average 18o decreases with latitude reflecting the trend of rainfall and riverwater 18o with latitude over the northern american continent

sea fan corals provide a stable isotope baseline for assessing sewage pollution in the mexican caribbean we compared stable nitrogen isotope 15 n values from the common caribbean sea fan gorgonia ventalina collected from a developed and undeveloped coastline to test the hypothesis that sewage derived nitrogen n inputs are detectable and more severe in developed areas along the mesoamerican barrier reef of mexico the akumal coast was selected as the developed site since this area is inhabited by thousands of local residents and has a significant flux of tourists it was compared to a relatively undeveloped shoreline south of mahahual a small town with a few hundred residents and sewage treatment infrastructure gorgonians sampled from akumal were relatively enriched in 15 n as high as 7 7 nearshore and were 3 5 greater than sea fans from mahahual collected at similar depths while previous work has shown that water column n concentrations are uniform around akumal 15 n values of sea fans sampled parallel to shore were variable indicating that sewage derived n inputs are spotty along the coast 15 n values were positively correlated with fecal enterococcus counts from seawater confirming that these enrichments are associated with sewage and not denitrification we suggest that the data from mahahual can be used as an isotopic baseline for monitoring the mesoamerican barrier reef at sites where increased development is planned or underway

an abrupt drowning of the black sea shelf abstract during latest quaternary glaciation the black sea became a giant freshwater lake the surface of this lake drew down to levels more than 100 m below its outlet when the mediterranean rose to the bosporus sill at 7 150 yr bp 1 saltwater poured through this spillway to refill the lake and submerge catastrophically more than 100 000 km2 of its exposed continental shelf the permanent drowning of a vast terrestrial landscape may possibly have accelerated the dispersal of early neolithic foragers and farmers into the interior of europe at that time

holocene paleoecology and paleoceanography of the southwestern black sea shelf revealed by ostracod assemblages abstract the holocene replacement of ponto caspian ostracod assemblages by mediterranean species is studied in two long composite cores m02 45 a composite of cores m02 45p m02 45 t and m05 03p and m05 50 a composite of cores m05 50p and m05 51g acquired at sites 69 m and 91 m deep on the southwestern black sea shelf composite core m02 45 was collected from the middle shelf and composite core m05 50 was acquired on the distal fringe of the eastern levee of a saline underflow channel emanating from the strait of bosphorus sixteen radiocarbon dates in m02 45 and nine in m05 50 are used to construct age models which show recovery of sediments as old as 12 915 cal yr bp m02 45 site and 12 010 cal yr bp m05 50 site a total of 45 ostracod species are identified in the two cores from 12 000 to 7425 cal yr bp the ostracod assemblage is dominated by ponto caspian species mainly loxoconcha sublepida l lepida and tyrrhenocythere amnicola donetziensis from 7425 to 6315 cal yr bp the assemblage consists of nearly equal abundances of mediterranean species cytheroma variabilis in m02 45 sagmatocythere littoralis in m05 50 and the ponto caspian species after 6315 cal yr bp to the tops of the cores the assemblage is dominated by mediterranean species including palmoconcha agilis carinocythereis carinata hiltermannicythere rubra and pterygocythereis jonesii cluster analysis further subdivides the stratigraphic succession into six bioecozones with different ostracod assemblages the changes in the ostracod assemblages from one bioecozone to the next indicate that progressive environmental changes took place on the southwestern black sea shelf from at least 7500 cal yr bp to the present the first hint of changing conditions at 7500 cal yr bp lags the initial reconnection to the mediterranean sea through the strait of bosphorus by 2000 yr demonstrating that black sea salinity increased slowly and took that long to reach values tolerable to marine ostracod immigrants widespread colonization by mediterranean species took even longer 3000 years from the time of the initial reconnection

changes in coastline positions during the holocene in the shelf of the northwestern black sea the first evidence for the reconnection of the black sea with the mediterranean sea are euryhaline mollusc species that appear in the bottom sediments lacustrine conditions existed over the larger part of study area at the beginning of the holocene early holocene beds are characterized by a wide distribution of continental facies e g lacustrine marshy and alluvial the lacustrine phase was followed by a marine phase and the transition occurred around ca 8 9 8 5 ka bp the holocene was marked by a gradual increase of mytilus sp shells in sediments reconstructions of coastline positions during the holocene in the northwestern black sea shelf are presented extensive sampling of the study area during several decades allowed the acquisition of a comprehensive data base for paleogeographic reconstructions positions of ancient coastlines are discussed analysis of relief features lithological composition and bottom sediments distribution and faunal complexes allowed identification of paleofacies in the northwestern part of the black sea facial and paloegeographic maps of the holocene discrete time intervals such as the bugazian from ca 10 5 10 to 8 9 8 5 ka bp the vityazevian from ca 8 9 8 5 to 7 1 6 2 ka bp the kalamitian from ca 7 1 6 2 to 4 1 4 0 ka bp and the dzhemetinian from ca 4 1 4 0 to present are presented dating of the sediments is based on uncalibrated radiocarbon determinations study of the granulometry of sediments provided evidence that supports the proposed ancient coastline positions the samples from the cores recovered from different facial zones enabled the characterization of sedimentological environments for each time interval the position of the early holocene coastal sediments is marked out on the level of modern isobaths approximately from 25 to 35 m in the range of time from ca 8 9 8 5 to 7 1 6 2 ka bp the coastline was located at depths from 20 to 25 m the position of the coastline which existed from ca 7 1 6 2 to 4 1 4 ka bp is allocated on the level of modern isobaths from 0 to 15 m comparison of the various positions of the coastline and their facies changes through time indicates that the holocene transgression had a progressively and oscillatory course

can molluscan assemblages give insights into holocene environmental changes other than sea level rise a case study from a macrotidal bay marennes oleron france during the late holocene the rate of sea level rise decreased and climate changes hydrodynamic processes or anthropogenic impacts became predominant parameters governing the sedimentary infill of estuarine environments the aim of this study is to describe the response of past benthic mollusc communities to these forcing factors mollusc skeletal remains were sampled from three 8000 5500 and 2600 year long sedimentary records in the marennes oleron bay atlantic coast france where environmental changes have previously been identified thanks to a combination of very high resolution seismic profiles and sedimentological data molluscan assemblages successfully record environmental changes even at the smallest temporal scale they provide relevant information regarding bathymetry salinity hydrodynamics oxygen content and sediment supply in the 8000 year long record the transition from an upper to a lower intertidal mudflat community provides evidence of a transgressive phase that occurred between 8000 and 7600 years bp in the 5500 year long record an oyster bank developed on the slopes of a tidal channel has been recovered the composition of the fossil community and the careful examination of skeletal remains suggest that the channel was hydraulically inefficient in response to the sediment infilling of its drainage area in the 2600 year long record a soft bottom shallow water subtidal mollusc community similar to that found nowadays in the marennes oleron bay has been recovered from both lower mixed sand mud and upper muddy units separated by a major regional unconformity dated to about 1000 years bp this sharp transition is recorded by a few rare species and was responsible for the local extinction of the bivalve lepton squamosum however the abundance of the most common species and the quantity of fragmented shells remain stable which may indicate that mud drape deposition was related to an increase in mud supply rather than a decrease in water energy the level of detail of the palaeoenvironmental reconstructions varies depending on the ecological requirements of the species stenotypic indicator species provide accurate quantitative information whereas eurytypic species add undesired variability to the assemblages since fossil molluscs are easy to collect and to identify and provide long term smoothed records of environment variations this study suggests that they can be used prior to any other biological proxy as a first step into reconstructions of holocene coastal environments

paleoenvironments in russkaya gavan fjord nw novaya zemlya barents sea during the last millennium the 6 m long sediment core asv 987 was collected from the deep part of the glaciated russkaya gavan fjord at the northwestern coast of novaya zemlya barents sea in 1997 r v akademik sergei vavilov the core was investigated for lithology grain size coarse debris organic carbon foraminifera macrobenthic remains and stable isotopes in foraminiferal tests age control was provided by seven ams 14 c ages the recovered sedimentary section spans approximately 800 years from ca 1170 ad the proxy records reveal variations in sedimentation processes bioproductivity glacier front position seaice conditions and the hydrographic regime in the fjord these characteristics are interpreted in terms of regional and global climatic changes during the last millennium we distinguish four stages in the development of sedimentary environments in russkaya gavan which generally correspond to major climatic events the medieval warm period mwp the early and late phases of the little ice age lia and recent warming the most pronounced change in sedimentation regime occurred at the onset of the lia ca 1400 presumably due to the advance of a glacier into the fjord subsequent evolution of sedimentary environments included stabilization and retreat of the glacier front the most recent facies are interpreted to indicate a change towards warmer conditions d 2004 elsevier b v all rights reserved

the effect of ponding depth on infiltration in a crusted surface depression over the past few decades the influence of surface sealing on infiltration has been the subject of numerous publications however very few of these experiments have considered the effect of spatial variability in seal hydraulic characteristics on infiltration field and laboratory observations have demonstrated that seal characteristics vary considerably within a range of a few cm and the changes are often related to microtopography the objective of this experiment was to investigate the influence on infiltration of a seal with varying hydraulic properties in a surface depression two soils of different aggregate stability were used in the experiment blosseville silt loam and villamblain silty clay loam soil columns 23 cm diameter by 30 cm length were packed with aggregates of 2 0 cm and a 6 cm depression was formed in the soil surface a sedimentary crust was formed in the centre of the depression and the sample was rained upon for 60 min at a rainfall intensity of 35 mm h 1 subsequently water outflow at the base of the column and pressure heads in the column were measured during two ponding periods corresponding to depths of 0 5 and 4 0 cm water outflow rates increased with ponding depth substantially more than could be attributed to the increases in ponding pressure head and submerged area for both soils the experiment demonstrated that where seal hydraulic conductivity varies with microtopography a significant increase in infiltration rate occurs as areas of greater hydraulic conductivity are submerged the increases in ponded pressure head and submerged area are negligible compared to the influence of spatial variability in seal hydraulic conductivity

pedosedimentary reconstruction of a thick loess paleosol sequence near lanzhou in north central china abstract a 38 m well section near lanzhou at the semiarid western margin of the loess plateau china contained a continuous high resolution loess paleosol sequence spanning the last 130 000 yr depth functions of micromorphological features magnetic susceptibility calcium carbonate organic carbon and median grain size provide the basis for pedosedimentary and associated paleoenvironmental reconstructions of three paleosol complexes s1 sm and s0 each pedosedimentary stage reflects the interaction of changing intensities of controlling monsoonal forces three periods of reduced dust inputs and enhanced pedogenic activity notably bioturbation and weak leaching can be identified from within the s1 pedocomplex these soil forming intervals were separated by phases of varying land surface instability characterized by arid dust deposition semiarid accretionary pedogenesis water reworking and crust formation or even freeze thaw modification the sm pedocomplex represents an interval of relatively rapid dust accumulation with only minimal syndepositional modification and minor pedogenic alteration at ephemeral land surfaces the s0 pedocomplex is clearly more pedogenically developed although erosion reworking and mixing by water have partly homogenized the property depth functions

holocene palaeogeographical reconstruction of the western part of naxos island greece abstract naxos island is situated in the cycladic plateau middle aegean sea and consists of concaved beach zones separated by small headlands this study investigates the diachronic palaeo shoreline shift due to the sea level change and its effect to the palaeo environmental evolution of the western coastal part of naxos island during the late holocene for this purpose six boreholes were drilled and dated using radiocarbon techniques the associated geomorphological sedimentological and paleontological investigation concluded that during late holocene the embayments of naxos western coastal part were frequently exposed and their communication with the sea was not perennial the coastal area was wider with many active lagoons and embayment changing from shallow marine environment to coastal environment frequently alternating to brackish mesohaline one the former sea level position in western naxos island should be between 1 5 m and 2 m during the last 2000 years which may partly reflect eustatic processes and partly a gradual or coseismic land subsidence

the effect of seasonal rainfall on nutrient input and biological productivity in the yax chen cave system ox bel ha mexico and implications for μxrf core studies of paleohydrology abstract lakes and speleothems from mexico s yucatan peninsula have been used extensively over the past decades for paleoclimate studies however aquifer condition and its response to climate change has received little attention cenotes sinkholes and coastal caves have been shown to record the paleohydrology of the aquifer but there is little information on sedimentation in these cave systems and its response to climate change newly developed xrf instrumentation for the analysis of cores can achieve subannual resolution due to small measurement increments but short period studies examining weathering inputs and rainfall have not yet been undertaken hindering paleoenvironmental interpretations of lake and cave sediment records this study examines the spatial and temporal relationship of cave sediment geochemistry in the anchialine cave system of yax chen quintana roo mexico sediment traps n 51 were placed at seventeen stations along the 2 7 km flooded cave system which transitions from mangrove to upland forest terrain with cenotes of variable size and frequency along its length sediment traps were collected every 6 months from may 2013 may 2017 along with rainfall and groundwater level data there are distinct responses of lithogenic fe ti sr limestone weathering and biogenic influenced si k s phytoplankton and mangrove sediment elements in the sediment samples associated with seasonal rainfall and hurricanes while lithogenic elements ti k show a direct relationship seasonal rainfall the sedimentation of biologically influenced si ti elements exhibit a 6 12 month lagged response with large rainfalls such as hurricane ingrid in 2013 and other tropical storms throughout the study period

response of loess materials to simulated translocation by water micromorphological observations structural differences between loess material deposits produced by splash flow without splash and by rainwash i e combined splash and flow respectively were reported earlier mucher and de ploey 1977 deposits from splash alone proved to be non layered and had incurred almost no additional particle sorting deposits from flow without splash were well layered while individual laminae displayed excellent sorting rainwash produced poorly layered deposits with poorly sorted individual laminae only horizontal and subhorizontal bedding and no cross bedding were observed similar features appeared in samples from naturally layered loess deposits collected from excavations the present paper focuses on the granulometric character of the artificially created layers experiments normally involved the combined use of an erosion and a sedimentation flume slope angles of the flumes varied mainly form 0 25 to 4 degrees precipitation intensities varied from 7 to 120 mm per hour unit discharges ranged from 0 2 to 9 2 cm3 cm s flow was laminar or smooth turbulent either subcritical or supercritical froude numbers between 0 5 and 3 8 raindrop impact had little influence on the flow velocity and thickness of the surficial water film but it significantly increased transportation capacity and flow competence savat 1976 1977 undisturbed samples were collected during the experiments and impregnated with unsaturated polyester resin thin sections of 20 m thickness were studied under a polarizing microscope comparative observations were made on naturally layered loess materials during rainwash clay size particles are removed and exported whereas laminae with particles from 10 to 50 microns are more frequently produced than those with particles from 10 to 30 microns flow without splash produced relatively more laminae with grains smaller than 30 microns diameter striking in all samples is the absence of laminae composed of 30 50 m grains aggregates were only deposited by smooth turbulent flow either disturbed or undisturbed by raindrop impact in view of the experimental results the naturally formed loess deposits may be interpreted as follows the bulk of the loess from the excavation near tongrinne belgium was reworked under influence of turbulent rainwash only one sample contained laminae consisting of clay particles smaller than 10 m and of particles from 10 30 m respectively suggesting deposition from flow without splash this was taken from a gully infilling a gully fill from the excavation heverlee near leuven belgium is characterized by poorly sorted laminae dominated by the coarser silt fractions this suggests infilling under influence of turbulent rainwash

hydraulic calculations of postglacial connections between the mediterranean and the black sea a series of simple hydraulic calculations has been performed to examine some of the questions associated with the reconnection of the black sea to the mediterranean through the turkish strait system during the holocene ryan et al s catastrophic flood scenario whereby the erosive power of the marine in fluxes initiated after eustatic sea level reached the sill depth opened up the bosphorus allowing saline water to pour into the black sea and filling it on a short time scale is examined the calculations show that although it might be possible to fill the palaeo black sea within the order of a decade a 1 2 year filling time scale is not physically possible a hydraulic model is also used to examine the more traditional connection hypothesis of near continuous freshwater outflow from the black sea with a slowly increasing saline inflow from the mediterranean beginning around 8 9 kyr bp the model considers two forms for the structure of the bosphorus a shallow sill as seen today and a deep sill associated with no sediments filling the 100 m gorge above the bedrock in the strait sensitivity experiments with the hydraulic model show what possible strait geometric configurations may lead to the black sea reaching its present day salinity of 18 psu salinity transients within the black sea are shown as a function of time providing for values that can be validated against estimates from cores to consider a deep non sediment filled bosphorus 100 m deep the entry of mediterranean water into the sea of marmara after 12 0 kyr bp is examined a rapid entry of marine water into the sea of marmara is only consistent with small freshwater fluxes flowing through the turkish strait system smaller than those of the present day by a factor of at least 4 such a small freshwater flux would lead to the salinification of the black sea being complete by an early date of 10 2 9 6 kyr bp thus the possibility of a deep bosphorus sill should be discounted

constraints on black sea outflow to the sea of marmara during the last glacial interglacial transition new cores from the upper continental slope off romania in the western black sea provide a continuous high resolution record of sedimentation rates clay mineralogy calcium carbonate content and stable isotopes of oxygen and carbon over the last 20 000 yr in the western black sea these records all indicate major changes occurring at 15 000 12 800 8400 and 7100 yr before present these results are interpreted to reflect an evolving balance between water supplied by melting glacial ice and other river runoff and water removed by evaporation and outflow the marked retreat of the fennoscandian and alpine ice between 15 000 and 14 000 yr is recorded by an increase in clays indicative of northern provenance in black sea sediments a short return toward glacial values in all the measured series occurs during the younger dryas cold period the timing of the first marine inflow to the black sea is dependent on the sill depths of the bosporus and dardanelles channels the depth of the latter is known to be 80 5 m which is consistent with first evidence of marine inundation in the sea of marmara around 12 000 yr the bedrock gorge of the bosporus reaches depths in excess of 100 m relative to present sea level though it is now filled with sediments to depths as shallow as 32 m two scenarios are developed for the connection of the black sea with the sea of marmara one is based on a deep bosporus sill depth effectively equivalent to the dardanelles and the other is based on a shallow bosporus sill less than 35 m in the deep sill scenario the black sea s surface rises in tandem with the sea of marmara once the latter connected with the aegean sea and black sea outflow remains continuous with inflowing marine water gradually displacing the freshwater in the deep basin the increase in the 18 o of mollusk shells at 12 800 yr and the simultaneous appearance of inorganic calcite with low 18 o is compatible with such an early marine water influx causing periodic weak stratification of the water column in the shallow sill scenario the black sea level is decoupled from world sea level and experiences rise and fall depending on the regional water budget until water from the rising sea of marmara breaches the shallow sill in this case the oxygen isotope trend and the inorganic calcite precipitation is caused by increased evaporation in the basin and the other changes in sediment properties reflect climate driven river runoff variations within the black sea watershed the presence of saline ponds on the black sea shelf circa 9600 yr support such evaporative drawdown but a sensitive geochemical indicator of marine water one that is not subject to temperature salinity or biological fractionation is required to resolve whether the sill was deep or shallow

stable isotopic variation in pteropods and atlantids from north pacific sediment traps abstract to determine their usefulness in paleoenvironmental studies and to better understand isotopic equilibrium in biogenic aragonite carbon and oxygen isotopic analyses were performed on six species of pteropod and two species of atlantid collected with free drifting sediment traps from the north pacific ocean where the depth habitat of a species is constrained enough to permit estimation of the ambient temperature and water 18o the isotopic compositions of the shells are close to aragonite water 18o equilibrium with the ambient water none of the fauna are in 13c equilibrium with the dissolved bicarbonate assuming aragonite water equilibrium fractionation the 18o values of the shells provide reasonable average depths of shell growth the distribution is as follows 1 shallow water species 125 m l bulimoides small the 18o variation within specimens of c columnella a large easily sectioned species is complex with no clear record of seasonality however some minor seasonal effects are observed the 13 c values within specimens consistently show a 1 2 decrease from the caudal septum to the aperture perhaps reflecting increased incorporation of metabolic co2 with age

the implications of spatial variability in surface seal hydraulic resistance for infiltration in a mound and depression microtopography abstract soil surface crusting has a major impact on water infiltration and erosion in many soils considerable progress has been made in describing crusting processes and in modelling the impact of crusting on infiltration most studies however have neglected the high spatial variability in crust characteristics observed in the field the objective of this experiment was to determine the influence of runoff depth on infiltration rate in the presence of a surface seal varying in hydraulic characteristics with microtopography the blosseville silt loam has a low aggregate stability and forms crusts readily the villamblain silty clay loam has a greater aggregate stability due to its greater clay and organic matter contents and it is more resistant to aggregate breakdown processes under rainfall samples of the soils were sieved to retain aggregates less than 2 0 cm and packed in 50 50 15 cm soil trays the trays were surrounded by a 10 cm soil border to compensate for splash loss after molding the surface into a mound and depression microtopography the samples were subjected to simulated rainfall at an intensity of 22 8 mm h 1 hourly measurements of surface roughness showed that the original roughness was smoothed out due to the infilling of depressions by sediments detached from the mounds for the final hour runon was added to the top of the soil tray to increase the runoff rate and depth for both soils infiltration rate increased more than could be attributed to the increased ponding pressure head the change in infiltration rate was particularly great for villamblain the measurements of hydraulic resistance showed that structural crusts had a lower hydraulic resistance than sedimentary crusts they also showed that the crusts formed on villamblain were of a lower hydraulic resistance than those of blosseville it appears that small changes in runoff depth can significantly increase infiltration rate when structural crusts of lower hydraulic resistance are inundated the effect was less important in blosseville which formed seals of relatively high hydraulic resistance everywhere the results provide a suitable explanation for field observations of increasing infiltration rate with either increasing rainfall intensity or runoff rate the results also have implications for the relationships between surface roughness surface water storage and infiltration

bulk density of surface crusts depth functions and relationships to texture abstract a range of soils from pleistocene deposits with sandy to sandy loam textures and a group of loess derived soils with predominantly silty textures were subjected to 60 mm of simulated rainfall to form structural seals after drying samples of the surface crusts were collected to determine their bulk densities at a high resolution of depth 0 15 mm using an immersion method the bulk density data obtained for each soil sample were plotted as a function of depth beneath the soil surface two models were fitted to these plots the first was an exponential decay type function as proposed by mualem et al 1990 and the second was a sigmoidal type of function assuming that maximum compaction had already progressed to some depth below the soil crust surface all of the results indicated a gradual decrease in the bulk density with depth below the surface until convergence with the initial bulk density of the undisturbed soil was attained the maximum bulk densities recorded for crust segments representing the uppermost 2 mm of the crusts ranged from 1 713 to 1 91 g cm 3 for soils with silty sand loamy sand or sandy loam textures crusts of loess derived soils showed lower values ranging from 1 44 to 1 65 g cm 3 the maximum surface bulk density was shown to be highly significantly correlated with the log of geometric mean diameter of the primary grain size distribution in most cases both models showed good to very good fits to the measured data the exponential decay function appeared to better represent the initial stages of surface compaction and the sigmoidal function the later stages of structural crust formation

is the abrupt drowning of the black sea shelf at 7150yrbp a myth abstract sedimentological and chronostratigraphic studies of the coastal plain sediments of the black sea near the sakarya river turkey and seismic stratigraphic survey of the shelf sediments off this river s mouth were carried out the results indicate that just prior to its flooding by the mediterranean waters at about 7200 yr bp the black sea was a fresh water lake emptying its waters into the sea of marmara the water level of this lake was about 18 m lower than the present sea level but above the 35 m sill depth of the bosphorus this finding contradicts with ryan et al 1997a ryan et al 1997b hypothesis that the black sea lake water level was more than 100 m below the sill depth of the bosphorus and that the drowning of the black sea shelf at 7150 yr bp was abrupt

vegetation history and environmental development since ca 6000 cal yr bp in and around ispani 2 kolkheti lowlands georgia abstract the kolkheti lowlands of western georgia have a unique vegetation and a rich cultural history palynological and macrofossil analysis accompanied by ams 14c dates of the deposits of the ispani 2 mire near kobuleti allow the reconstruction of regional vegetation environmental history and local peatland development within the context of black sea level and cultural changes comparison of two adjacent peatland cores confirms spatial differences in wetland development prior to 5400 cal yr bp the ispani basin was a floodplain of an active river system where overbank deposits with fluvially transported castanea pollen were deposited subsequently a lake or lagoon developed in which reeds expanded these were succeeded by herb rich open alder carrs after 1900 cal yr bp carpinus and fagus expanded on the dry grounds where formerly quercus was more abundant also castanea declined local reedbeds that burned regularly succeeded the alder carr after 1000 cal yr bp a percolation bog developed resulting in the formation of 4 m of loose porous and largely undecomposed sphagnum austinii peat with molinia roots the upper 50 cm of the analysed section show extensive human impact on the landscape during the 20th century

controls on the age of vascular plant biomarkers in black sea sediments abstract transfer of organic carbon oc from the terrestrial to the oceanic carbon pool is largely driven by riverine and aeolian transport before transport however terrigenous organic matter can be retained in intermediate terrestrial reservoirs such as soils using compound specific radiocarbon analysis of terrigenous biomarkers their average terrestrial residence time can be evaluated here we show compound specific radiocarbon 14c ages of terrigenous biomarkers and bulk 14c ages accompanied by geochemical proxy data from core top samples collected along transects in front of several river mouths in the black sea 14c ages of long chain n alkanes long chain n fatty acids and total organic carbon toc are highest in front of the river mouths correlating well with bit branched and isoprenoid tetraether indices which indicates contribution of pre aged soil derived terrigenous organic matter the radiocarbon ages decrease further offshore towards locations where organic matter is dominated by marine production and aeolian input potentially contributes terrigenous organic matter average terrestrial residence times of vascular plant biomarkers deduced from n c29 31 alkanes and n c28 30 fatty acids ages from stations directly in front of the river mouths range from 900 70 years to 4400 170 years these average residence times correlate with size and topography in climatically similar catchments whereas the climatic regime appears to control continental carbon turnover times in morphologically similar drainage areas of the black sea catchment along transect data imply petrogenic contribution of n c29 31 alkanes and input via different terrigenous biomarker transport modes i e riverine and aeolian resulting in aged biomarkers at offshore core locations because n c29 31 alkanes show contributions from petrogenic sources n c28 30 fatty acids likely provide better estimates of average terrestrial residence times of vascular plant biomarkers moreover sedimentary n c28 and n c30 fatty acids appear clearly much less influenced by autochthonous sources than n c24 and n c26 fatty acids as indicated by increasing radiocarbon ages with increasing chain length and are thus more representative as vascular plant biomarkers

nature formation and effects of soil crusts formed by water drop impact abstract research was conducted to investigate 1 the structure formation and nature of soil crusts which develop as a result of raindrop impact under controlled conditions of simulated rain and 2 the crust effect on infiltration rates scanning electron microscope sem observations performed on sandy sandy loam and clayey soil samples show the crust to be composed of two layers 1 a skin 0 1 mm thick and 2 a layer 2 3 mm thick with a higher bulk density in which aggregates have been destroyed a washing in zone described by earlier investigators could not be detected the soil beneath the crust maintains its original structure and particle orientation the chemical composition of the rain water was found to have a significant but not very large effect on the infiltration rate vs cumulative rain curve of the clayey soil material only final infiltration rate was about 20 lower when distilled water was applied compared to tap water electrical conductivity 0 6 mmho cm 1 an increase of the bulk density from 1 35 1 48 g cm 3 in undisturbed soil to 1 74 1 88 g cm 3 in crusts was found the amount of eroded material increased gradually with increase of runoff and decrease of infiltration at steady state the erosion rates were 0 45 1 25 and 0 76 g m 2 min 1 in the sandy sandy loam and clayey soil specimens respectively percentages of clay and silt in the eroded material were higher than in the bulk samples three stages to describe the changes in nature and effects of crusts during their formation are suggested 1 the rate of infiltration decreases to a point at which runoff beings 2 the initiation of runoff until infiltration and runoff rates become stabilized and 3 infiltration and runoff maintain steady rates

micromorphological study of slumping in a hardsetting seedbed under various wetting conditions slumping of hardsetting seedbeds upon wetting has not been extensively studied despite the likelihood that it determines the physical properties after drying slumping results from processes similar to those involved in crusting except that overburden pressure can dominate rather than rainfall kinetic energy only a few studies have dealt with the morphological description of slumping to simulate different climatic and management conditions repacked seedbeds of a hardsetting sandy loam soil were subjected to a range of wetting conditions e g capillary rise immersion and rainfall simulation slumping processes were characterized using qualitative and quantitative micromorphological observations of polished blocks and thin sections from resin impregnated samples a morphogenetical framework was proposed to help description of the complex associations of processes which can lead to structural collapse crusting and slumping on wetting three main stages were considered i e aggregate disruption or abrasion relocation of the released material and compaction in the hardsetting material studied here structural collapse under slow wetting occurred at the bottom of cores due to aggregate coalescence under overburden pressure coalescence required aggregate cohesion being reduced by microcracking therefore it differed from the coalescence previously described in unstable silty loam soils where microcracking was not necessary for aggregates to coalesce macroporosity decreased most strongly under fast wetting due to physical dispersion and aggregate breakdown under simulated rainfall compaction by raindrops could not be distinguish from aggregate breakdown the role of overburden pressure and of rainfall kinetic energy remains to be stated new data are required including measurement of total porosity in the initial wet and dry states

degradation of soil structure by welding a micromorphological study abstract in 1985 a plot study was started on sloping cultivated loess soils in south limbourg the netherlands to evaluate the effects of various cropping systems of fodder maize on runoff soil loss and crop yield under natural rainfall to monitor degradation of soil structure including crust formation undisturbed vertical samples 15 7 cm for soil micromorphological analysis were taken of the top 7 cm of soil at ten dates chosen in relation to times of tillage and sowing crop stage harvest and winter frost wheel marks if present were also sampled contrary to accepted views no disintegration of structural elements by slaking or dispersion was observed freshly tilled soil exhibited a loss of its original granular structure by coalescence of the aggregates into larger units eventually leading to a structureless state of part of the top soil processes held responsible for this are mainly welding of wet aggregates and seldom fusion by silt infillings in vertical inter aggregate pores the two layer model of soil crust formation of mcintyre could not be confirmed as no important vertical translocation of fines or washed in layers were observed horizontal cracks developed in the structureless soil giving rise to a platy structure in part of the top soil transitional stages of loss of soil structure were observed characterized by the progressive reduction of compound packing voids to vughs which ultimately disappeared completely and sometimes were replaced by planar voids besides structural crusts sedimentary crusts including splash deposits were observed

paleoenvironmental changes on the northeastern and southwestern black sea shelves during the holocene abstract four paleoceanographic events are distinguished during the holocene based on changes in macro and microfossil assemblages studied from three sediment cores ak 521 522 2571 from the outer northeast shelf and from core mar02 45 situated on the southwest shelf of the black sea west to the bosphorus the lithology and fossils were previously studied from cores ak 521 and ak 522 and mar02 45 however high resolution ostracod analyses from the ams 14 c dated core ak 2571 allowed for a revision of the taxonomy and paleoecological interpretation of this microfaunal group on the ne shelf downcore changes in the relative abundance of the polyhaline ostracods are found to be contemporaneous in all three cores from the ne shelf as a result centennial millennial scale fluctuations of the bottom water salinity are resolved in the area a broader scale examination of paleoenvironmental changes between the ne and sw shelves is also made and the surface to bottom salinity gradient is discussed an uncalibrated radiocarbon based chronology is used throughout this paper to facilitate comparison with the regional chronostratigraphy of marine transgression and regressions in the black sea the calibrated ages corrected for the changes in reservoir age through the holocene are also provided the first paleoceanographic event is associated with the pulse of mediterranean water previously established at about 9 8 9 3 ka bp this event is clearly observed in the sw region but not on the ne shelf due to a hiatus in the longest core ak 521 the second event is represented on both the ne and sw shelves as a replacement of brackish benthic fauna and surface phytoplankton with marine ones between 8 4 and 6 9 ka bp indicating a gradual increase in salinity the third event is marked by opposing trends in surface and bottom water salinity changes on the ne shelf bottom water salinity rose to modern values by 6 5 ka bp and then decreased within the interval 6 4 5 3 ka bp as recorded by the ostracod assemblages on the sw shelf surface water salinity reached modern values by 5 6 ka bp and remained constant until present day as inferred from the dinoflagellate cyst assemblages the fourth event is marked by a recurring increase in bottom water salinity to modern values indicated by the polyhaline ostracod assemblages at 5 3 ka bp in the ne region after which only minor salinity fluctuations are observed

land use effects on soil crusting and hydraulic response of surface crusts on a tropical alfisol soil surface crusting a common phenomenon on cultivated soils has major implications for agriculture and the environment because of its effects on soil hydrological properties erosion and crop establishment the objectives of this study were to evaluate land use controls on crust formation and the hydraulic response of soils to crust development for a patancheru series soil clayey skeletal mixed isohyperthermic udic rhodustalf in south central india soil aggregates obtained from cultivated pl and naturally vegetated fallow nv land were packed into sample trays and subjected to laboratory rain simulation to form crusts thin sections and visual observation indicated that crust development reached a more advanced stage in the pl case compared with nv following 90 min of rain at 40 80 mm h 1 intensity this was reflected in a thicker crust layer with fewer voids in the former and a less smooth surface with partially disintegrated aggregates in the latter the hydraulic response of the soil surface with the progression of crust development indicated a more permeable and less dense crust formed on nv than on pl soil the results suggested that nv soil aggregates were more stable and that crust formation is more gradual for stable aggregates compared with the less stable pl aggregates a structural crust type formed on the patancheru soil by means of parallel subprocesses involving translocation and illuviation of aggregate disruption by products and raindrop compaction and particle rearrangement copyright 1999 john wiley sons ltd

the holocene history of the ne black sea and surrounding areas an integrated record of marine and terrestrial palaeoenvironmental change here we present an almost complete and integrated holocene record of marine and terrestrial palaeoenvironmental change from the ne shelf of the black sea a dinoflagellate cyst record used to recon

effects of crust and cracks on simulated catchment discharge and soil loss sealing crusting and cracking of crusts of the soil surface has been observed in many parts of the world in areas with sandy silty and loamy soils sealing and crust formation occurs under the influence of rain storm and drying weather with prolonged drying surface crusts might crack leading to complex situations with respect to infiltration and runoff generation cracking of crusted loamy soils appears to be a general process this study aims to measure the hydraulic properties of fully crusted and cracked crusted areas and to evaluate the effects of these measurements on catchment discharge and soil loss in a loess region of the netherlands using the lisem soil erosion model samples with minimum infiltration rates fully crusted and with maximum infiltration rates cracked crusted surfaces were taken from fields with bare soil or winter wheat and their soil hydraulic functions were measured the results of these measurements were used as input in the lisem soil erosion model simulations of discharge and soil loss were done for each of these two land uses and for two rain events additionally simulated discharge and soil loss under actual recorded land use were calculated in all cases soils with no surface cracks produced higher figures for discharge and soil loss than those where 10 of the surface crust was cracked for a good interpretation of the results for soil loss the spatial distribution of cracked crusted areas and fully crusted areas has to be investigated in detail to deal with cracked crusted and fully crusted areas in simulation modelling care has to be taken to accurately measure the soil physical functions representing the maximum and minimum infiltration rates an assignment of these functions to calculation grids has to be made as the lisem model is capable of assigning different soil physical functions to each calculation grid an improved prediction of the soil physical behaviour of the catchment can be simulated

deltas south of the bosphorus strait record persistent black sea outflow to the marmara sea since 10 ka at the southern exit of the bosphorus strait in the northeastern marmara sea high resolution seismic profiles reveal two lobate progradational delta lobes in modern water depths of v40 65 m the younger delta was active from v10 to 9 ka based on radiocarbon dates of equivalent prodelta deposits and the elevation of its topset to foreset transition the topset to foreset transition climbs in the seaward direction because the delta prograded into a rising sea low abundances of marine fauna and flora in the 10 9 ka interval support a deltaic interpretation there are no rivers in the area that could have fed the delta instead all evidence points to the strait itself as the source of sediment and water when this outflow was strongest v10 6 6 0 ka sapropels accumulated in basinal areas of both the aegean and marmara seas benthic foraminiferal and dinoflagellate cyst data from contemporary deposits elsewhere in the marmara sea point to the continual presence through the holocene of a surface layer of brackish water that we ascribe to this same outflow from the black sea through the bosphorus strait by v9 1 8 5 ka two layer flow developed in the bosphorus strait as global sea level continued to rise and the sediment supply to the younger delta was cut off because the outflowing black sea water ceased to be in contact with the floor of the strait the older delta lobe lies below a prominent lowstand unconformity and is tentatively interpreted to have formed from v29 5 to 23 5 ka oxygen isotopic stage 3 when the marmara sea stood at v355 m and a second sapropel accumulated in deep basinal areas crown copyright 2002 elsevier science b v all rights reserved

pollen stratigraphy of late quaternary cores from marmara sea land sea correlation and paleoclimatic history marine pollen analysis is an important tool for paleoclimatic reconstruction of regions like the eastern mediterranean and near east where few onshore sites provide long pollen records first a compilation was made of core top data from the eastern mediterranean to blackseas to map regional variations in modern marine pollenspore concentrations these data show a strong linkbetween pollen spore concentrations and sea surface salinity with minima of 5 grains g in the southern mediterranean and maxima of 160 000 grains g in the blacksea despite under representation of some forest and herbaceous vegetation indicators e g fagus and pistacia variations in species composition of the marine assemblages correspond closely with the distribution of regional vegetation zones and can be used as proxies for spatial differences in seasonal and total temperature and rainfall pollen spore assemblages in five cores from the marmara sea with multiple ages ranging from 33 550 to 1990 yr bp and one holocene core from southeastern blacksea were used to compile a late quaternary marine pollen stratigraphy these data were then compared with eastern mediterranean onshore reference sites in order to reconstruct a vegetation and paleoclimate history for the blacksea aegean corridor from the pleniglacial interval to present five marine pollen zones are recognized pz 5 v33 6 24 ka corresponds to the late wu rm pleniglacial pz 4 v24 13 ka spans the late glacial maximum lgm pz 3 v13 10 2 ka includes the allero d younger dryas glacial interglacial transition pz 2 10 2 4 ka marks the early holocene interglacial warm wet interval and pz 1 covers the latest holocene colonization phase which may also have been cooler and drier using the steppe forest index of traverse 1975 it is shown that the only intervals of severely dry conditions occurred briefly during the lgm and its transition during most of the pleniglacial and all of the postglacial time precipitation versus evaporation rates were sufficiently high to permit persistence of oro mediterranean forest vegetation furthermore there is no evidence for environmental conditions in the blacksea marmara region that would have encouraged pastoral or agricultural settlement in the littoral region prior to the bronze age commencing 4600 years ago crown copyright a 2002 elsevier science b v all rights reserved

holocene sea level oscillations and environmental changes on the eastern black sea shelf abstract a multi proxy study of four sediment cores from the eastern caucasian black sea shelf revealed five transgressive regressive cycles overprinted on the general trend of glacioeustatic sea level rise during the last 11 000 14c yr these cycles are well represented in micro and macrofossil assemblages sedimentation rates and grain size variations the oldest recovered sediments were deposited in the neoeuxinian semi freshwater basin 10 500 9000 14c yr bp and contain a caspian type mollusk fauna dominated by dreissena rostriformis low 18o and 13c values are measured on this species the first appearance of marine mollusks and ostracodes from the mediterranean is established in this part of the black sea at 8200 14c yr bp i e about 1000 2000 yr later than the appearance of marine microfossils in the deeper part of the sea the early holocene bugazian to vityazevian condensed section of shell and shelly mud sediments with at least two hiatuses represent a high energy shelf edge facies it contains a transitional assemblage representing a mixture of caspian and mediterranean fauna this pattern suggests a dual flow regime via the bosphorus after 8200 14c yr bp caspian species disappear and oligohaline species decrease in abundance during the vityazevian prekalamitian cycle later during the middle to late holocene low sea level stands are characterized by shell layers whereas silty mud with various mollusk and ostracode assemblages rapidly accumulated during transgressions restricted mud accumulation as well as benthic faunal composition and abundance suggest high energy and well ventilated bottom water during low sea level stands a trend of 18o enrichment in mollusk shells points to an increase in bottom water salinity during the vityazevian to kalamitian transgressions 7000 to 5700 14c yr bp due to a more open connection with the mediterranean while a pronounced increase in polyhaline species abundance is established during the kalamitian to djemetean transgressions 6400 to 2700 14c yr bp however the composition of the faunal assemblage indicates that bottom water salinity never exceeded modern values of 18 20 psu

physical characterization spectral response and remotely sensed mapping of mediterranean soil surface crusts abstract soil surface crusting and sealing are frequent but unfavorable processes in mediterranean areas soil crust and seals form on bare soil subject to high intensity rainfall resulting in a hard impenetrable layer that impedes infiltration and hampers the germination and establishment of plants the adverse consequences of overland flow and reduced fertility can lead to erosion and ongoing degradation therefore information on the distribution of surface crusts and their physical properties is essential to combat the undesired effects of crust formation in e g soil erosion and soil compaction we studied the occurrence of crusts in a study area in mediterranean southern france our objectives were to compare the physical and hydrological properties of the crusts and underlying soil to identify the spectral characteristics 400 to 2500 nm of the crusted and non crusted soil surfaces using high resolution field spectra and to investigate the potential of mapping crust occurrence using airborne hyperspectral hymap images the differences in some physical properties between crusted and non crusted surfaces are significant while others are only marginal crusting markedly reduces the infiltration capacity and crust strength varies between the different soil types spectral differences are small mainly in albedo values overall reflectance and in absorption band depth and shape albedo differences range from 8 to 40 differences in absorption band features in the spectra of crusts and non crusted surfaces are small sixty percent of the crusted soil surfaces showed stronger absorption features in the clay mineral absorption bands at 2200 nm than non crusted soils increased absorption is due to a relative enrichment in fines spectral feature fitting and linear spectral unmixing algorithms were applied to airborne hymap images to evaluate the possibilities of mapping surface crusts crusts could be mapped in fallow agricultural fields but the spectral response of natural badlands was too fragmented for crust mapping

microgeometrical characterisation and percolation threshold evolution of a soil crust under rainfall abstract an experiment has been carried out in order to both measure the unsaturated hydraulic conductivity of a soil crust when it is developing and to characterize its macro and microstructural evolution five stages of a structural crust developing in a loamy clay soil have been identified mercury intrusion experiments and micromorphological descriptions have provided information on the structural evolution of the crust at the microscale quantitative image analysis from images of the crust microstructure has led to the definition of a particle erosion index at the microscopic scale which is the mean chord length calculated in the solid phase this index decreases from 60 to 11 m during the whole experiment the lowest value being recorded at the fourth stage specific measurements of the percolation threshold in the soil crust at different stages during its formation have given quantitative data to interpret the modifications of the unsaturated hydraulic conductivity of this crust when it develops the percolation threshold decreases from 130 m at the second stage down to 40 m at the fifth stage between the same stages the unsaturated hydraulic conductivity at 5 kpa decreases from 12 2 to 4 7 cm h both the structural information given by the chord size distribution and the functional information obtained from the percolation threshold can be related to propose a new model of soil crusting

early holocene marine flooding of the black sea abstract echo sounding data recorded in the black sea in 1969 imaged a chain of hills 5 to 150 m high at a depth of 2000 2200 m that resemble hills on the lower continental rise like those hills the features in the western black sea may have been created by bottom currents the easterly flowing currents inferred to have formed the hills may be related to a catastrophic flood of the black sea from the sea of marmara 7150 yr ago

environmental changes on the inner northeastern black sea shelf off the town of gelendzhik over the last 140 years abstract a comprehensive multi proxy study of mini core ash 2009 08 from the inner shelf of the northeastern black sea allowed us to define recent environmental changes in the area on a sub decadal resolution the age model of the core based on radionuclide 210pb and 137cs measurements suggests an average sedimentation rate of 2 mm y and consequently a sedimentary record spanning the last 140 years overall four fossil groups studied from the core indicate subtle environmental changes the dinocyst assemblages show stable surface water conditions with a possible cooling in the 1930s 1950s and a slight decline in salinity from the 1960s which corresponds to an increase in precipitation and the fresh water balance of the black sea known from the published instrumental data a gradually increasing abundance of the heterotroph species suggests a nutrient increase from the 1920s ostracods and molluscs demonstrate rather stable bottom water salinity and biotopes over the last 75 years changes in abundance of ostracods and benthic foraminifers as well as changes in the mollusc diversity most likely reflect variations in trophic conditions with the higher food supply to the sea floor in the 1940s 1960s and from the late 1990s enhanced bottom water energy is inferred from the mollusc enrichment and a relatively high content of the fine sand grain size fraction in the 1990s in the pollen assemblages trees mainly represented by pinus strongly prevail over herbs throughout the record however the trees to herbs ratio demonstrates a slight decline from the 1920s most likely resulting from human impact on the vegetation of the nearby land

last glacial holocene paleoceanography of the black sea and marmara sea stable isotopic foraminiferal and coccolith evidence multi proxy data and radiocarbon dates from several key cores from the black sea and marmara sea document a complex paleoceanographic history for the last v30 000 yr the marmara sea was isolated from both the black sea and the aegean sea during glacial periods when global sea level lowering subaerially exposed the shallow sills at the straits of bosphorus and dardanelles i e lake stage and reconnected through both straits during interglacial periods when rise of global sea level breached the shallow sills i e gateway stage micropaleontological data show that during the lake stage the surface water masses in both the marmara sea and black sea became notably brackish however during the gateway stages there was a low salinity surface layer and normal marine water mass beneath two sapropel layers are identified in the marmara sea cores sapropels m2 and m1 were deposited between v29 5 and 23 5 ka and v10 5 and 6 0 ka respectively micropaleontological and stable isotopic data show that the surface water salinities were reduced considerably during the deposition of both sapropel layers m2 and m1 and calculation using planktonic foraminiferal transfer functions shows that sea surface temperatures were notably lower during these intervals the presence of fauna and flora with black sea affinities and the absence of mediterranean fauna and flora in sapropels m1 and m2 strongly suggest that communication existed with the black sea during these times a benthic foraminiferal oxygen index shows that the onset of suboxic conditions in the marmara sea rapidly followed the establishment of fully marine conditions at v11 10 5 ka and are attributed to black sea outflow into the marmara sea since 10 5 ka these suboxic conditions have persisted to the present the data discussed in this paper are completely at odds with the flood hypothesis of ryan et al 1997 and ryan and pitman 1999 crown copyright 2002 elsevier science b v all rights reserved

permanence of soil surface crusts on abandoned farmland in the central ebro basin spain abstract surface crusts are frequently found on fallow land in the semi arid ebro basin spain and are an important factor in land degradation soil surface sealing leads to a decrease in infiltration rates and a consequent increase in runoff thereby accelerating sheet wash and rill erosion thin sections were used to analyse the development and structures of the different crusts found across the ridge furrow field pattern rainfall simulations experiments and infiltration measurements show the runoff generation and the soil erosion rates on the crusts the spatial distribution of crusts was documented using large scale aerial photographs taken from a remote controlled hot air blimp splash and slaking cause structural crusts to form on the ridges while eroded material leads to a build up of sedimentary crusts in the furrows a platy structure as well as vesicles then develop in these crusts depending on the amount of time that has elapsed since ploughing and the frequency of wetting and drying cycles alluvial fan crusts develop on material accumulated at the end of erosion rills the increase in the runoff of up to 81 and the decrease in infiltration rate up to 4 6 mm h 1 on surface crusts were quantified

morphology genesis and classification of surface crusts in loamy and sandy soils abstract in an attempt to organize the knowledge of soil crusting processes and to group soil crusts on the basis of common morphological features and physical properties we synthesized and reinterpreted information from previous publications as a result we propose a classification system for surface crusts formed by rainfall in loamy and sandy soils although this system does not aim to be comprehensive it was designed from the study of a great number of crust samples collected in the temperate and tropical zones thus corresponding to a wide range of environmental and land use conditions three main classes of crusts structural erosion and depositional were distinguished each with subclasses where possible correspondence has been made with former systems this system helps predict infiltrability in accounting not only for total porosity of surface crusts but also for pore shape and continuity since crust classes are genetically related this classification system also supplies some insight into predicting soil degradation and selecting the most suitable control techniques

morphological characterization of soil crust development stages on an experimental field abstract crust development on a loamy aquic hapludalf near paris was studied in an experimental field to which various fertilizers and amendments had been applied these treatments over a period of 57 years had induced a range of organic matter contents and exchangeable cation percentages the macroscopic aspects of the soil surface was closely monitored during crusting and microscopic characterization was carried out at every main crust development stage crusting followed a general pattern 1 sealing of the soil surface by a structural crust 2 development of a depositional crust even in the sodic plot where the depositional crust appeared especially early the structural crust developed first the change from the first stage to the second one mainly depended on a decrease in infiltrability due to the structural crust properties that induced micro runoff and puddling under rainfall structural crust development seemed to involve a coalescing process due to raindrop impact when moistening decreased soil cohesion this process developed much faster in the sodic than in the limed plot morphology of the depositional crust in particular microbedding and sorting could be related to the hydrodynamic behaviour of the soil surface abundance size and duration of puddles

catastrophic flooding of the black sea abstract decades of seabed mapping reflection profiling and seabed sampling reveal that throughout the past two million years the black sea was predominantly a freshwater lake interrupted only briefly by saltwater invasions coincident with global sea level highstand when the exterior ocean lay below the relatively shallow sill of the bosporus outlet the black sea operated in two modes as in the neighboring caspian sea a cold climate mode corresponded with an expanded lake and a warm climate mode with a shrunken lake thus during much of the cold glacial quaternary the expanded black sea s lake spilled into to the marmara sea and from there to the mediterranean however in the warm climate mode after receiving a vast volume of ice sheet meltwater the shoreline of the shrinking lake contracted to the outer shelf and on a few occasions even beyond the shelf edge if the confluence of a falling interior lake and a rising global ocean persisted to the moment when the rising ocean penetrated across

origin migration pathways and paleoenvironmental significance of holocene ostracod records from the northeastern black sea shelf micropaleontological studies of the black sea including ostracod records have suggested that early holocene salinity values were between 5 and 10 practical salinity units psu contrasting with present values of 18 22 psu however more precise paleoenvironmental reconstructions based on ostracod assemblages require additional information related to their modern ecological affinities this study uses modern species information collected from samples with living fauna to interpret the fossil holocene assemblages of two sediment cores ak 2575 and ak 521 collected from the northeastern outer shelf of the black sea a total of 37 ostracod species are recorded in the fossil assemblages with 2 related to freshwater oligohaline environments 23 from caspian type environments and 12 from environments similar to the mediterranean three distinct assemblage zones are identified from the caspian type dominating in the early holocene up to 7 4 cal ka bp a mixed assemblage of caspian type and mediterranean type from 7 4 to 6 8 cal ka bp and a progressive dominance of mediterranean species from 6 8 cal ka bp it is very likely that the dominant control of ostracod species occurrence during the period up to 6 8 cal ka bp is salinity a range of factors including temperature biotope and sedimentation rates influenced the species distribution over the last 6 8 cal ka bp

prompt transgression and gradual salinisation of the black sea during the early holocene constrained by amino acid racemization and radiocarbon dating abstract the restricted environment of the black sea is particularly sensitive to climatic and oceanographic fluctuations owing to its connection with the mediterranean sea via the narrow bosphorus strait the exact mechanism and timing of the most recent connection between these water bodies is controversial with debate on the post glacial history of the black sea being dependent on radiocarbon dating for numerical ages here we present new 23 accelerator mass spectrometer ams radiocarbon ages on peat and bivalve molluscs supported by the first amino acid racemization aar dating of bivalve molluscs n 66 in the black sea these data indicate infilling of the black sea during the early holocene from an initial depth 107 m below sea level and 72 m below that of the bosphorus sill these data combined with a review of previous radiocarbon ages has enabled a unique perspective on the post glacial black sea a sea level curve based on conventional and ams radiocarbon ages on peat and ams based ages on dreissena sp shells indicate the water level in the earlier lake phase continued until the early holocene to be lower than the bosphorus sill after the younger dryas ended however the absence of ams dated mollusc ages from the shelves of this basin older than the younger dryas is suggestive of sub aerial exposure of the shelves and comparatively lower water levels when the younger dryas began thus post glacial outflow from the black sea occurred through a lowered or open bosphorus seaway basin wide radiocarbon ages on peat indicate a prompt increase in water level from that of the pre existing and unconnected palaeo lake during the earliest holocene 9600 9200 cal a bp mass colonisation of the black sea by mediterranean taxa did not occur until salinity had risen sufficiently a process which took 1000 a or more from the initial transgressive event this gradual change in salinity contrasts with the prompt transgression which would have taken 400 a to occur

impact of skeletal heterogeneity and treatment method on interpretation of environmental variability from the proteinaceous skeletons of deep sea gorgonian octocorals abstract the stable isotope geochemistry of gorgonian octocoral skeletons facilitates detailed time series reconstructions of nutrient biogeochemistry however comparisons among reconstructions from different locations require realistic estimates of the uncertainty surrounding each measured geochemical value here we determine quantitative uncertainties related to 1 standard skeletal pretreatment in preparation for stable isotopic analysis and 2 biological variability associated with a heterogeneous isotopic composition of the gorgonin skeleton we found that the 5 hcl pretreatment required for the 13c measurements does not significantly impact the 15n values of the skeleton nor the reproducibility of the 15n measurements in contrast while 5 hcl pretreatment significantly altered bulk 13c values via removal of caco3 it did not change amino acid 13c values in the organic skeleton we found that the variance of repeat measurements of skeleton samples formed contemporaneously and homogenized skeleton for both 13c and 15n exceeded that of instrumental uncertainty of an acetanilide standard this indicates that instrumental uncertainty underestimates the true precision of an isotopic measurement of the organic skeleton furthermore measurements of contemporaneous skeleton around the circumference of an octocoral colony yielded variability exceeding that of homogenized skeleton based on these results we find that 1 both 13c and 15n values can be measured simultaneously in pretreated skeleton 2 growth bands should be homogenized prior to analysis and 3 reported error should include uncertainty due to biological effects determined from repeat analysis of homogenized skeleton and not just instrument error to reduce false significant differences our results present an important protocol for processing proteinaceous octocoral skeletons and propagating uncertainty to more accurately reconstruct nutrient dynamics from proteinaceous deep sea octocoral skeletons

proteinaceous corals as proxy archives of paleo environmental change abstract high resolution marine data are critical to evaluating anthropogenic impacts on our environment considering the spatial and temporal limitations of direct instrumental measurements proxy data extracted from marine environmental archives are necessary to separate anthropogenic changes from those that would occur naturally the majority of late holocene high resolution environmental reconstructions are derived from marine carbonates including tropical scleractinian corals bivalves crustose coralline algae and sclerosponges however these archives are restricted to the top hundreds of meters of the water column and only preserve environmental variability that is captured by calcium carbonate skeletons at a very few select locations marine sediments archive annual environmental variability in organic and inorganic materials recently additional types of corals are proving to yield information complimentary to these traditional marine archives including cold water scleractinian corals and proteinaceous corals a taxonomically diverse group the proteinaceous corals are broadly defined as those having a branching gross morphology with skeleton comprised at least partly of protein rich organic material they encode characteristics of their food and ambient environment into the chemical and physical composition of their skeleton this environmental encoding combined with their banded skeleton and significant longevity means that proteinaceous corals hold information in their skeleton that helps fill the spatial and temporal gaps in our knowledge of past and present ocean conditions here i review the environmental reconstructions derived from geochemical measurements of the proteinaceous coral skeletons this information is grouped into the mesopelagic environmental variability captured in the skeleton of bamboo corals surface processes captured in the organic skeletons of corals across all ocean depths and environmental variability documented by skeletal radiometric isotopes we include animals from two separate subclasses within the class anthozoa including the parasitic zoanthids that secrete a sclero proteic skeleton since the proteinaceous corals are taxonomically diverse we consider the unique features that define this group of corals including their distribution morphology nutrition and longevity we find that uncertainty surrounding biological parameters limits the precision of reconstructions derived from the calcitic skeleton in contrast analytical effort and cost constrain the number of reconstructions from the organic skeleton through this discussion we provide insights into the uses challenges and directions for future research for this important environmental archive

nitrogen isotopic composition of organic matter from a 168 year old coral skeleton implications for coastal nutrient cycling in the great barrier reef lagoon abstract ongoing human activities are known to affect nitrogen cycling on coral reefs but the full history of anthropogenic impact is unclear due to a lack of continuous records we have used the nitrogen isotopic composition of skeleton bound organic matter cs 15 n in a coastal porites coral from magnetic island in the great barrier reef as a proxy for n cycle changes over a 168 yr period 1820 1987 ad the magnetic island inshore reef environment is considered to be relatively degraded by terrestrial runoff given prior cs 15 n studies from other regions there was an expectation of both secular change and oscillations in cs 15 n since european settlement of the mainland in the mid 1800s surprisingly cs 15 n varied by less than 1 5 despite significant land use change on the adjacent mainland over the 168 yr measurement period after 1930 cs 15 n may have responded to changes in local river runoff but the effect was weak we propose that natural buffering against riverine nitrogen load in this region between 1820 and 1987 is responsible for the observed stability in cs 15 n in addition to coral derived skeletal 15 n we also report for the first time 15 n measurements of non coral derived organic n occluded within the coral skeleton which appear to record significant changes in the nature of terrestrial n inputs in the context of previous cs 15 n records most of which yield cs 15 n changes of at least 5 the magnetic island coral suggests that the inherent down core variability of the cs 15 n proxy is less than 2 for porites