sedimentary impacts of anthropogenic alterations on the yeongsan estuary south korea abstract over the last half century coastal zones within the republic of korea s korea have experienced a wide range of engineered coastal modifications including construction of seawalls extensive land reclamation and installation of estuarine dams the yeongsan estuary has experienced all of these modifications and provides an ideal case study on how sedimentation changes within a macrotidal estuary in response to these alterations combined these alterations have considerably modulated the timing and intensity of river discharge prevented natural tidal exchange modified the shoreline profile and altered the transport of sediment and organic matter within the coastal zone these impacts have been investigated using 30 gravity cores analyzed for 210 pb radioisotope geochronology laser diffraction particle size analyses 13 c and 15 n isotope ratio mass spectrometry and x radiography average sediment accumulation rates range from 0 9 0 6 cm yr 1 to 10 0 2 9 cm yr 1 with the highest rates proximal to the downstream side of the dam and some areas determined to be either actively eroding or recently dredged these results are supported by comparison of multiple bathymetric surveys and chirp seismic data suggest an order of magnitude increase from average holocene sediment accumulation rates side scan sonograms collected adjacent to the dam reveal distinctive scouring transitioning to areas accumulating fine grained sediments shifts in the organic matter source inputs are apparent in pre post dam sediments and reflect the occluding of tidal influence above the dam resulting in increasingly terrestrial dominated signatures additionally a time series of cores collected during periods of limited and high discharge analyzed for 7 be indicates sediment deposition occurs episodically corresponding to high discharge dam releases our observations record a shift in depositional environments as a response to an extensive array of anthropogenic alterations ultimately land reclamation and dam construction have severely altered the fate and transport of sediment within the estuarine system as a consequence sedimentation rates have increased dramatically and depositional events are primarily controlled by discharges from the estuarine dam

role of corrosion by h2so4 fallout in cave development in a travertine deposit evidence from sulfur and oxygen isotopes abstract 18o and 34s values for spring water dissolved sulfates and sulfides air borne sulfur species and gypsum found on the walls of two caves in the travertine deposit of the cave and basin hot springs in banff national park alberta canada suggest that the caves are developing at least in part via a chemical corrosion process microbiological reduction of dissolved sulfate with positive 18o and 34s values produces reduced sulfur species hs h2s with negative 34s values upon escape from the spring water the h2s is converted to h2so4 fallout h2so4 attacks the calcite in the travertine leading to the formation of gypsum the gypsum on the walls of the caves has negative 34s values similar to those of the reduced sulfur species and negative 18o values that reflect incorporation of an appreciable proportion of oxygen derived from spring water vapor during h2s oxidation hydrolysis isotopically similar gypsum in spring pools at the site represents gypsum that has fallen off the walls exposing fresh travertine to attack by sulfuric acid

relationships between extratropical sea level pressure variations and the central pacific and eastern pacific types of enso abstract this study examines the linkages between leading patterns of interannual sea level pressure slp variability over the extratropical pacific 20 60 n and the eastern pacific ep and central pacific cp types of el nino southern oscillation enso the first empirical orthogonal function eof mode of the extratropical slp anomalies represents variations of the aleutian low and the second eof mode represents the north pacific oscillation npo and is characterized by a meridional slp anomaly dipole with a nodal point near 50 n it is shown that a fraction of the first slp mode can be excited by both the ep and cp types of enso the slp response to the ep type is stronger and more immediate the tropical extratropical teleconnection appears to act more slowly for the cp enso during the decay phase of ep events the associated extratropical slp anomalies shift from the first slp mode to the second slp mode as the second slp mode grows subtropical sst anomalies are induced beneath via surface

controlling factors of rhythmic sedimentation processes on an intertidal estuarine mudflat role of the turbidity maximum in the macrotidal seine estuary france the aim of this study is to analyse and to quantify the fine particles transfer i e 7 1 m then deposition of spm from the turbidity maximum becomes important allowing fine particles to settle on the mudflat where the current velocities are low 0 4 m s 1 on tides of lower range 7 1 m bed elevation levels suggest that erosion of the mudflat surface dominates however dewatering processes also occur in the soft mud deposits resulting in compaction during periods of wave activity and periods of increasing river discharge the mudflat surface experiences rapid erosion these periods of erosion sudden or progressive imply a transfer of fine grained material from the mudflat surface back into the tm the long term 22 months high frequency 1 measurement every 10 min and high resolution 0 6 mm dataset obtained from the altimeter allows quantification of the volume of material exchanged between the intertidal area and the estuarine standing stock of spm the maximum of deposition on the studied mudflat during the study was of 27 cm with highest deposition occurring after the periods of highest river flow and implying that between 25 and 40 of the maximum estimated mass of spm held within the estuarine tm 300 000 500 000 t had been temporarily deposited on the mudflat likewise following periods of resuspension by wave activity bed elevations reduced by an order of 1 cm suggesting a release of between 1 1 5 of the tm load from the mudflat back into suspension the study shows that lateral exchanges of sediment between the intertidal reaches of the estuary and the water column are an important part of the sediment budget and that the supply of sediment available for deposition i e the tm has a causal relationship with sedimentation rates experienced by intertidal mudflats

accretion of a new england u s a salt marsh in response to inlet migration storms and sea level rise sediment accumulation rates were determined at several sites throughout nauset marsh massachusetts u s a a back barrier lagoonal system using feldspar marker horizons to evaluate short term rates 1 to 2 year scales and radiometric techniques to estimate rates over longer time scales 137cs 210pb 14c the barrier spit fronting thespartina dominated study site has a complex geomorphic history of inlet migration and overwash events this study evaluates sediment accumulation rates in relation to inlet migration storm events and sea level rise the marker horizon technique displayed strong temporal and spatial variability in response to storm events and proximity to the inlet sediment accumulation rates of up to 24 mm year 1were recorded in the immediate vicinity of the inlet during a period that included several major coastal storms while feldspar sites remote from the inlet had substantially lower rates trace accumulation to 2 2 mm year 1 during storm free periods accumulation rates did not exceed 6 7 mm year 1 but remained quite variable among sites based on137cs 3 8 to 4 5 mm year 1 and210pb 2 6 to 4 2 mm year 1 radiometric techniques integrating sediment accumulation over decadal time scales the marsh appeared to be keeping pace with the relative rate of sea level rise from 1921 to 1993 of 2 4 mm year 1 at one site the210pb based sedimentation rate and rate of relative sea level rise were nearly similar and peat rhizome analysis revealed thatdistichlis spicatarecently replaced this onces patenssite suggesting that this portion of nauset marsh may be getting wetter thus representing an initial response to wetland submergence horizon markers are useful in evaluating the role of short term events such as storms or inlet migration influencing marsh sedimentation processes however sampling methods that integrate marsh sedimentation over decadal time scales are preferable when evaluating a systems response to sea level rise

anthropogenic influence on sedimentation and intertidal mudflat change in san pablo bay california 1856 1983 analysis of a series of historical bathymetric surveys has revealed large changes in morphology and sedimentation from 1856 to 1983 in san pablo bay california in 1856 the morphology of the bay was complex with a broad main channel a major side channel connecting to the petaluma river and an ebb tidal delta crossing shallow parts of the bay in 1983 its morphology was simpler because all channels except the main channel had filled with sediment and erosion had planed the shallows creating a uniform gently sloping surface the timing and patterns of geomorphic change and deposition and erosion of sediment were influenced by human activities that altered sediment delivery from rivers from 1856 to 1887 high sediment delivery 14 1 10 6 m 3 yr to san francisco bay during the hydraulic gold mining period in the sierra nevada resulted in net deposition of 259 14 10 6 m 3 in san pablo bay this rapid deposition filled channels and increased intertidal mudflat area by 60 37 4 3 4 to 60 6 6 2 km 2 from 1951 to 1983 23 3 10 6 m 3 of sediment was eroded from san pablo bay as sediment delivery from the sacramento and san joaquin rivers decreased to 2 8 10 6 m 3 yr because of damming of rivers riverbank protection and altered land use intertidal mudflat area in 1983 was 31 8 3 9 km 2 similar to that in 1856 intertidal mudflat distribution in 1983 however was fairly uniform whereas most of the intertidal mudflats were in the western part of san pablo bay in 1856 sediment delivery through its affect on shallow parts of the bay was determined to be a primary control on intertidal mudflat area san pablo bay has been greatly affected by human activities and will likely continue to erode in the near term in response to a diminished sediment delivery from rivers 2007 elsevier ltd all rights reserved

patterns rates and possible causes of saltmarsh erosion in the greater thames area uk the estuary dominated coast of the greater thames in england has experienced rapid lateral erosion and internal dissection of saltmarshes this paper provides an overview of saltmarsh development in this area and re examines the role of environmental and human forcing factors it draws on documentary evidence including historical maps survey data and time series data of forcing factors lateral marsh retreat began in the 19th century in the medway and blackwater estuaries followed by other estuaries in the greater thames region at the beginning of the 20th century the outer estuaries and the wider parts of the inner estuaries especially have experienced erosion erosion has been modest in wave sheltered areas e g the colne and the inner crouch in the 1960s and more widely the 1970s a phase of rapid erosion took place with erosion rates of up to ca 16 ha year 1 per site notably along the open coast of dengie and foulness and in the blackwater and thames estuaries at all sites vertical sediment accretion was well able to keep up with sea level rise over the past century evidence indicates that there may have been several causes for the erosion of saltmarshes these are notably land claim and embankment construction increasing the tidal range and current velocities and a continuous rise of especially high and extreme water levels the latest episode of rapid erosion in the 1970s is largely attributed to changes in the wind wave climate for example erosion at wave exposed sites coincided with a peak in high magnitude waves combined with a high incidence of southeasterly waves the study shows that many factors including natural forcing factors and human activities have to be taken into account when explaining saltmarsh development

initial transient response of the winter polar stratospheric vortex to idealized equatorial pacific sea surface temperature anomalies in the ncar waccm abstractperpetual winter simulations using the ncar whole atmosphere community climate model waccm are conducted to document the differences of the initial transient response of the boreal winter northern hemisphere stratospheric polar vortex to central cpw and eastern pacific warming epw events idealized patches of positive sea surface temperature sst anomalies are superimposed onto a climatological sst field to mimic canonical cpw and epw forcings a 20 member ensemble was created by varying initial atmospheric conditions for both cpw and epw cases in the ensemble average the vortex weakens under both cpw and epw forcing indicated by a negative zonal mean zonal wind tendency this tendency is mainly tied to changes in the eddy driven mean meridional circulation mmc a negative anomaly in the eddy momentum flux convergence also plays a secondary role in the weakening the vortex response however differs dramatically among individual ensemble members a few ensemble members exhibit initial

sulfur isotope geochemistry of gypsiferous aridisols from central iran abstract gypsum accumulation is one of the prominent pedogenic processes occurring in many and regions of the world gypsiferous soils occur in large areas of the iranian central plateau the origin of gypsum in the aridisols of central iran and its distribution in different landscapes were studied using sulfur and oxygen isotopic composition of both solid and dissolved sulfates the results strongly support the hypothesis that the area was cut off from the tethys seaway at the end of the mesozoic era and as a result the lower cretaceous sulfate has controlled the s geochemistry of the younger sediments including the soils studied the mean values of 34 s and 18 o of the soil gypsum and of dissolved sulfate match with the average isotopic values of the marine sediments which are the most common soil parent materials the results also confirm that s and o in dissolved so 4 and so 4 in gypsum have not undergone any reduction and re oxidation reactions dissolution and reprecipitation appear to be the possible mechanisms responsible for the observed minimal isotope fractionation both 34 s and 18 o values of the soil gypsum decrease slightly with decreasing elevation in the study area these findings are important for understanding the landform evolution in this arid region

physical and chemical properties of the sulphur mountain thermal springs banff national park and implications for endangered snails nine thermal springs in three groups occur along the flank of sulphur mountain in banff national park the principal recharge zone is suggested to be above 2000 m elevation on mount rundle circulation depths are estimated to be 3 2 0 6 km and discharge is focused along the sulphur mountain thrust springs show constant temperature and total dissolved solids load throughout the winter whereas both drop in association with spring snowmelt the degree and timing of temperature drops are a function of elevation with the highest springs showing the earliest and most significant temperature drop the highest elevation springs also show the greatest seasonal variability in water chemistry unusual seasonal flow stoppages of these springs are related to extreme low precipitation years the biogeochemistry of the thermal springs and population fluctuations of the endemic and endangered banff springs snail physella johnsoni are strongly related to seasonal variability in flow rates changes in redox condi

34s and 18o abundances differentiate upper cambrian and lower devonian gypsum bearing units district of mackenzie n w t an update previous sulfur isotope data for the lower devonian bear rock formation and the upper cambrian saline river formation in the district of mackenzie n w t have been supplemented by additional sulfu

control of estuarine sediment dynamics by interactions between currents and waves at several scales abstract the effect of interactions between continuous tidal currents and intermittent waves processes on sediment dynamics and transport is addressed by presenting detailed field measurements of waves boundary layer currents and suspended sediment from an estuarine channel and an adjacent intertidal sandflat in manukau harbour new zealand the aim is to determine in what ways it is necessary to couple waves and currents in numerical models and thereby put limits on the fundamental structure of process based estuarine sediment transport models waves were important on the intertidal flat turbidity switched on and off with the appearance and disappearance of waves wave groups dominated entrainment of bed sediment a wave current boundary layer model explained measured bed shear stress and hydraulic roughness and the measured near bed time averaged suspended sediment concentration was mostly well predicted by a pure wave model both the waves themselves and wave related processes varied markedly over the tidal cycle the variation in the former principally changes in wave height was related to changes in fetch caused by the harbour wide emergence and submergence of intertidal regions the variation in the latter was related to changes in water depth relative to the wavelength of the waves which controlled the penetration to the bed of wave orbital currents in addition to the variation over the tidal cycle in the intensity of wave processes there was also a change in kind which occurred with the arrival at the measurement site of the turbid fringe which is the narrow highly turbid edge of the estuarine water body the relationship between suspended sediment concentration and wave orbital velocity in the turbid fringe was radically different to the relationship in the estuarine water body proper which suggests a change in dynamics perhaps related to breaking waves a hybrid modelling approach is required i e one that treats discrete events but resolves tidal cycle scale variation within the event there is a need to resolve the variation in the wave train over the tidal cycle and the penetration to the bed of wave orbital motions both of which could only be done adequately within an estuary tidal model in contrast to the situation on the intertidal flat where waves intermittently entrained sediment sediment transport in the channel was continuous driven by tidal currents to predict sediment flux in the channel we need to know the upstream sediment transporting capacity of the flow including that contributed by waves the character of the bed sediment and the sediment settling time scale these factors confounded even the simplest notion of flood and ebb dominance which frequently has been applied to understand estuarine morphodynamics

tropical extratropical geopotential height teleconnections during the northern hemisphere winter abstract simultaneous and lagged correlation statistics have been calculated between time series of seasonal height anomalies at selected stations and extratropical grid point anomalies in both hemispheres the tropical stations in two major tropical precipitation zones the indo china maritime continent and africa are well correlated with each other these stations are also correlated with stations in the north pacific and australia but the coefficients are smaller the correlations between height anomalies at any of these stations and northern hemisphere height anomalies show a well defined global pattern depending upon the location of the stations the pattern is either a pacific north american pna a tropical northern hemisphere tnh pattern or a mixed pattern having both elements all three patterns pna tnh and wpo western pacific oscillation have been linked to tropical variations the correlations between height anomalies at these well correlated stations and the southern hemisphere heig

microbes and mineral precipitation miette hot springs jasper national park alberta canada at miette hot springs so42 h2s ca2 sr2 and co32 rich waters with a mean temperature of 51 2 c are ejected from three spring vents and several minor seeps near the floor of sulphur creek valley runoff channels from the springs are colonized by cyanobacteria oscillatoria phormidium gloeocapsa synechococcus xenococcus that grow in resistant mats and as loose filaments within 0 5 m of the spring vents diatom assemblages cymbella mastagloia brachysira sellaphora rhopalodia nitzschia navicula pinnularia that dominate the flow paths 0 5 2 0 m from the vents and microbial mats with cyanobacteria and diatoms in the distal flow paths sulphate reducing bacteria and green algae are also present gypsum elemental sulphur and lesser quantities of calcite and strontianite precipitate from the spring waters microbial populations influence accumulation of mineral precipitates by i forming mats close to the spring vents on which crystals grow ii forming mats alongside the flow paths t

linking the infilling of the north branch in the changjiang yangtze estuary to anthropogenic activities from 1958 to 2013 abstract many tidally dominated estuaries of the world are experiencing variations in bottom topography due to changes in natural forcings and intensive human activities here we focus on the morphological evolution of the north branch nb a tidally dominated distributary of the changjiang estuary our analysis is based on long term bathymetric and hydrological data collected between 1950 and 2010 the results show that mean water depth channel volume below 0 m and channel volume below 5 m have respectively decreased by 43 53 and 92 in the last 50 years a reduction of the whole estuarine surface with aggradation in elongated tidal sand bars and erosion at the mouth are the main morphological variations of the nb while a decrease in channel volume below 5 m due to infilling is the second mode of morphological change while the drastic decrease in sediment load from upstream is likely unrelated to the silting of the nb local land reclamation along the banks is directly responsible for the reduction of estuarine surface area and related tidal prism between 1958 and 2013 enhanced flood tide currents resulted in a large import of sediments from offshore into the nb triggering a sustained decrease in channel volume below 0 m it is argued that the recovery of the funnel shaped configuration of the estuary by restoring mud flats over 0 m dredging the southern part of the estuary bend and forbidding land reclamation could prevent the silting of the nb otherwise the nb will likely vanish in few decades

rapid cold water formation and recrystallization of relict bryophyte tufa at the fall creek cold springs alberta canada the fall creek tufa is a relict mid to late holocene freshwater carbonate spring deposit that is formed almost entirely of calcite encased cratoneuron commutatum gametophytes the spring is presently active emitting 13 c meteorically derived waters but it is not precipitating calcite wood embedded in the youngest part of the tufa yielded a radiocarbon 14c date of 310 50 years bp the oldest parts of the deposit could not be dated by radiocarbon methods because of a lack of embedded organics the fall creek tufa however probably began forming 5000 years bp in response to the same wet climatic conditions that initiated calcite precipitation at miette hot springs in jasper national park and the cave and basin hot springs in banff national park the relict deposit is composed largely of calcite cements that were precipitated around the bryophytes with lesser amounts of internal sediments the tufa formed through a repeated four stage developmental process that involved i encrustation ii enc

new typologies for estuarine morphology new theories to explain how tides and river flow determine estuarine bathymetries have been developed the range of validity of these theories has been subsequently assessed against a recently available observational data set success in reproducing the evolution of estuarine bathymetries that has occurred over the last 10 000 years provides the basis for the translation here of these theories into new typologies these then provide reference frameworks to enhance our perspective on existing morphologies and identify anomalous estuaries further refinement of these new theories requires analyses of causal factors responsible for such anomalies drawing on classical morphological experience these frameworks can also be used for calculating likely future bathymetric adjustments for prescribed changes in mean sea level tidal amplitudes river flow and sediment supply

origin of radioactive barite sinter flybye springs northwest territories canada cold springs emerging a long the contact between devonian limestone and shale units in the northwestern canadian cordillera are presently depositing a radium enriched barite sinter a geological cross section through the springs area shows that groundwaters could circulate through a mainly limestone aquifer to depths of approximately 2 km some shales and volcanic rocks associated with the aquifer contain barium bound in feldspars barite pyrite and organic matter hosted in shale and radium in feldspars or produced by the radioactive decay of uranium associated with organic matter hosted in shale spring waters are of the type characteristic of water that has equilibrated with clay minerals a subsurface equilibration temperature of 34 c was determined by silica geothermometry and 31 c by magnesium corrected na k ca2 geothermometry emerging waters are partly mixed with surface runoff and therefore these temperatures represent only minimum values assuming a normal geothermal gradient these tem

variability in sulfur isotope records of phanerozoic seawater sulfate the s of seawater sulfate reflects processes operating at the nexus of sulfur carbon and oxygen cycles however knowledge of past seawater sulfate s values must be derived from proxy materials that are impacted differently by depositional and post depositional processes we produced new timeseries estimates for the s value of seawater sulfate by combining 6710 published data from three sedimentary archives marine barite evaporites and carbonate associated sulfate with updated age constraints on the deposits robust features in multiple records capture temporal trends in the s value of seawater and its interplay with other phanerozoic geochemical and stratigraphic trends however high frequency discordances indicate that each record is differentially prone to depositional biases and diagenetic overprints the amount of noise quantified from the variograms of each record increases with age for all s proxies indicating that post depositional processes obscure detailed knowledge of seawater sulfate s s value deeper in time

factors controlling the field settling velocity of cohesive sediment in estuaries abstract it has long been recognized that the suspended sediment concentration ssc is one of the major determinants for the flocculation of cohesive particles into sediment flocs in estuaries it is furthermore well known that the turbulent shear of the water significantly influences the flocculation process and the equilibrium settling velocity of flocculated sediment in a turbulent flow a vast number of authors have reported algorithms relating the median settling velocity w 50 to suspended sediment concentration however only a few studies have dealt with the impact of the turbulent shear in this paper expressed as the root mean square rms velocity gradient g in the water on the w 50 in situ there is a strong need to establish algorithms based on in situ measurements describing the dual impact of both ssc and g on the flocculation process and hence w 50 the present paper addresses this topic field settling velocities of suspended cohesive sediment have been measured in micro meso and macro tidal estuaries regression analyses between the w 50 ssc and g are presented it is shown that by including both g and ssc in the regression analyses a significant increase in the correlation of the description of w 50 and the controlling parameters from each area can be obtained a generic algorithm describing the data from all the investigated areas is suggested it works well within specific tidal areas but fails to give a generic description of the field settling velocity

facies and architecture of an estuarine tidal bar the trompeloup bar gironde estuary sw france abstract this study describes the sedimentary facies and internal architecture of a modern estuarine tidal bar present in the bay head delta of a wave and tide dominated estuary the gironde estuary in southwest france based on 51 cores 2 to 5 m long this work demonstrates that such bars are composite sedimentary bodies made up of individual sigmoidal sand units isolated from one another by thick muddy layers the bar appeared in the study area around 1874 since then its evolution has been characterized by phases of rapid downstream bar migration alternating with periods of bar abandonment during the periods of active bar progradation which commonly last between 10 and 20 years the bar progrades up to 7 km seaward and forms a narrow 200 800 m wide sand ridge up to 6 m thick during abandonment phases which also last around 10 20 years the bar is starved of sand and a mud layer 1 to 3 m thick is deposited the vertical succession formed by the seaward progradation of the tidal bar records these alternating phases of growth and abandonment a typical vertical succession in the bar system is 8 m thick and comprises several superimposed upward coarsening units of cross stratified sand deposited during phases of seaward progradation separated by a thick layer of thinner bedded mud and sand laminae deposited during phases of bar abandonment when a tidal bar builds up to the supratidal zone marshes accumulate and the bar becomes a permanent island in the estuary the large scale architecture of the bar is thus made of an alternation of potential sandy reservoir units and muddy internal seals the reservoir units are characterized by a sigmoidal shape the muddy layer which is deposited between the two sigmoidal units is a thick continuous potential internal seal this complex internal architecture is due to the fact that there is a considerable amount of mud present in the bay head delta of the gironde estuary it is thought to be representative of the architecture of tidal bars in the inner part of wave and tide dominated estuaries

searching for travertines calcretes and speleothems in deep time processes appearances predictions and the impact of plants common models for modern calcite precipitation in and around caves soils springs and streams involve co 2 supplied by thick high p co 2 biogenic soils which were probably thin or non existent before vascular plants indeed plant influenced chemical weathering might have caused accelerated terrestrial carbonate production from the devonian onwards however terrestrial carbonates have also been documented from the archaean proterozoic cambrian ordovician and silurian mechanisms which could have caused non marine carbonates to precipitate without organic rich soils are described and some geological events likely to have influenced non marine carbonate precipitation up to the origin of vascular plants are highlighted as organisms have evolved so have the petrographic characteristics of non marine carbonates some examples of this are also given here

an evaluation of models for the kinematic evolution of thrust and fold belts structural analysis of a transverse fault zone in the front ranges of the canadian rockies north of banff alberta abstract the prevailing piggyback conceptual model for the kinematics of thin skinned thrust and fold belts maintains that the main faults develop sequentially from the hinterland to the foreland and from the top to the bottom of the accretionary wedge moreover it presumes that when younger thrust faults originate overlying older thrust faults become inactive and are carried forward passively this appears to contradict the prevailing mechanical model for the evolution of thin skinned thrust and fold belts the critical coulomb wedge model which requires that lateral growth of the wedge must be accompanied by vertical thickening of the wedge crosscutting relationships along a transverse fault zone in the front ranges of the canadian rockies north of banff alberta and patterns of overprinting of thrust related folding on pre existing thrust sheets demonstrate substantial overlap in the times of displacement on four major thrust faults in this part of the front ranges the presumption that displacement on one major thrust fault ends when displacement on a younger underlying thrust begins is a fallacy there is no contradiction between the piggyback conceptual kinematic model and the critical coulomb wedge mechanical model for the evolution of thin skinned foreland thrust and fold belts the main faults do originate sequentially from the hinterland to the foreland and from the top to the bottom of the evolving wedge but displacement occurs simultaneously on several major faults

depositional facies and aqueous solid geochemistry of travertine depositing hot springs angel terrace mammoth hot springs yellowstone national park u s a petrographic and geochemical analyses of travertine de positing hot springs at angel terrace mammoth hot springs yellow stone national park have been used to define five depositional facies along the spring drainage system spring waters are expelled in the vent facies at 71 to 73 8c and precipitate mounded travertine composed of aragonite needle botryoids the apron and channel facies 43 728c is floored by hollow tubes composed of aragonite needle botryoids that encrust sulfide oxidizing aquificales bacteria the travertine of the pond facies 30 62 8c varies in composition from aragonite needle shrubs formed at higher temperatures to ridged networks of calcite and aragonite at lower temperatures calcite ice sheets calcified bubbles and aggregates of aragonite needles fuzzy dumbbells pre cipitate at the air water interface and settle to pond floors the prox imal slope facies 28 54 8c which forms the margins of terracette pools is composed of arcuate aragonite needle shrubs that create small microterracettes on the steep slope face finally the distal slope facies 28 30 8c is composed of calcite spherules and calcite feather crys tals despite the presence of abundant microbial mat communities and their observed role in providing substrates for mineralization the com positions of spring water and travertine predominantly reflect abiotic physical and chemical processes vigorous co 2 degassing causes a 12 unit increase in spring water ph as well as rayleigh type covariations between the concentration of dissolved inorganic carbon and corre sponding d 13 c travertine d 13 c and d 18 o are nearly equivalent to aragonite and calcite equilibrium values calculated from spring water in the higher temperature 50 738c depositional facies conversely

sulfur and oxygen isotopes in the gypsum deposits of the provalata sulfuric acid cave macedonia abstract sulfur stable isotopes from cave sulfates mainly gypsum have been used in a number of studies to trace the source of sulfur in caves formed by sulfuric acid but only few studies apply combined use of sulfur and oxygen stable isotopes to further understand the processes operating in sulfuric acid speleogenesis sas here we present results of a detailed study of the distribution of sulfur and oxygen stable isotopes within the gypsum deposits formed during sulfuric acid speleogenesis of provalata cave macedonia the 18o vs vsmow values range between 3 9 and 8 2 and the 34s vs cdt values between 7 5 and 0 7 we found a strong positive correlation between the 18o and 34s values with a 0 5 increase in the 34s for every 1 increase in the 18o indicating that both oxygen and sulfur isotopes were concurrently affected during the oxidation process we attribute these effects to be either due to environmental control concentrations of h2s and o2 or due to isotope fractionation during multi step microbial oxidation also affected by the environmental conditions additionally a shift of 1 85 in the 34s values prior to the h2s oxidation is found indicating evolution of the h2s 34s in the sas system the wide range of both 18o and 34s values in the gypsum deposits of the small provalata cave show that both the number of samples and their location can be an important factor for the understanding of sulfuric acid speleogenesis using stable isotopes

sedimentation on intertidal mudflats in the lower part of macrotidal estuaries sedimentation rhythms and their preservation the objective of this study is to propose an original approach to the analysis of the formation of intertidal rhythmites their preservation and the evaluation of sedimentation rates on estuarine mudflats three mudflats one from each of three estuaries were analysed using a combination of long term a year high frequency 1 burst 10 or 20 min and high resolution 0 2 cm altimeter datasets and x ray images of sediment cores collected during topographic surveys the results highlight the roles played by sediment supply hydrodynamics and morphology of the lower estuaries on the sedimentation rhythms while the sediment starved medway estuary kent uk remains stable at different time scales the annual sedimentation rates on the sheltered authie mudflat pas decalais france and the open seine mudflat normandy france are relatively high at 18 and 15 cm yr 1 respectively on the authie mudflat sedimentation rhythms correspond to the semi lunar cycle with a good correlation between tidal range and deposit thickness sedimentation occurs at the beginning of the recovery mean value of 0 25 cm per semi diurnal cycle and is not disturbed by wind induced waves in the lower seine estuary semi diurnal mechanisms of deposition occur mainly when the mudflat is covered by a minimal water height tidal range threshold value 7 1 m sedimentation rhythms are discontinuous and deposition occurs only during the highest spring tides mean deposit thickness is 0 6 cm per semi diurnal cycle controlled by the turbidity maximum and the long high tide slack 2 3 h the fluid mud is sensitive to wind waves in this open funnel shaped estuary which undergoes wind induced erosion 0 2 to 2 cm about 10 times per year comparison of altimeter datasets and lithology of the sediments cored at the same points provided improved understanding of the sediment record rhythms and the sedimentation events on the sediment starved medway mudflat the result of sediment processes is a single superficial lamina the elementary deposit in the authie bay corresponds to a semi lunar linked layer typical of sheltered environments on the lower seine mudflat sedimentation rhythms are linked to the highest spring tides i e the lunar cycle resulting from increased sediment availability related to the high suspended matter concentration in the turbidity maximum these results underline the complex response of intertidal mudflats to hydrodynamics and sediment supply conditions from the semi diurnal to the annual scales

hydrodynamics and sedimentation induced by large scale coastal developments in the keum river estuary korea abstract the macro tidal keum river estuary located in the eastern yellow sea has been suffering siltation and morphological change since 1994 to understand the effects of the large scale coastal developments on the sedimentation processes in the estuary hydrodynamic and sedimentary data collected from 1985 to 2002 were analyzed and numerical experiments of hydrodynamics were performed the sedimentation rate in the estuary increased by a factor of 1 9 from 3 5 10 6 to 6 7 10 6 m 3 y 1 after the construction of a dam in the upper reaches of the estuary in 1994 large part of the estuary is veneered by the muddy sediments noticeably which were rarely found before dam construction since then siltation has concentrated in the upper estuary rather than the lower the upstream transport and accumulation of fine grained sediments is due to 1 the change to flood dominance in the main channel i e the relative intensification of flood current and the flood directed residual current and 2 the decrease in transport capacity in the upper estuary i e the marked decrease in current velocity which was induced by dam construction the former has resulted in the ebb dominance of the gaeya channel a distributary in the north of the main channel the tidal pumping of fine sediments was reinforced not by the freshwater saltwater interaction but by the residual tidal circulation the sediment fluxes observed in 2001 2002 demonstrate year round net inflow both at the entrance of the jetties and at the gaeya channel which implies that the sediments delivered by the keum river are entirely confined to the estuary incapable of escaping to the sea the net inward transport of fine sediments may accumulate pollutants adsorbed to or absorbed in the sediment grains in the estuary thus deteriorating the benthic environment gradually and the water quality eventually

oxygen and sulfur isotope geochemistry of acidic groundwater discharge in british columbia yukon and district of mackenzie canada the paint pots in kootenay national park british columbia appear to derive the fe zn pb and contents of their water from sulfide mineralization in lower and middle cambrian carbonates the fe zn ni and contents of groundwater discharging into a tributary of engineer creek yukon are likely derived from sulfide mineralization in devonian or ordovician black shales exposed in the area the high fe and contents of a natrojarosite deposit northeast of fort norman northwest territories are probably derived from pyritiferous cretaceous shales in that area isotope analyses of water and of dissolved and precipitated sulfur species from these three sites where acidic heavy metal bearing groundwater is being discharged revealed that between 38 and 74 of the oxygen used in the subsurface oxidation of metal sulfides is supplied by h2o molecules rather than by molecular dissolved oxygen the available data also suggest that lower percentages of water oxygen in the secondary sulfates reflect increasing

isotope geochemistry of dissolved precipitated airborne and fallout sulfur species associated with springs near paige mountain norman range n w t 34s values determined for dissolved sulfate in water discharged by sulfurous springs near paige mountain identify gypsum beds in the lower devonian bear rock formation as the sulfate source whereas relatively low 18o values show that as much as 30 of the sulfate may have gone through a reduction re oxidation cycle reduced sulfur species in the spring water have negative 34s values as a result of microbiological isotope fractionation during sulfate reduction airborne sulfur species h2s so2 h2so4 and gypsum formed through reaction of h2so4 fallout with exposed carbonate rocks show similar negative 34s values negative 18o values for the sulfate radical in h2so4 fallout and in the alteration product indicate that more than half of the oxygen reacting with airborne h2s is derived from water vapour

rapid coastal geomorphic change in the river murray estuary of australia abstract the river murray estuary a ramsar wetland site has experienced considerable rapid coastal change during the quaternary the interplay of aeolian processes river flows tidal oscillations wave action and variations in relative sea level due to global sea level changes and land subsidence provides the energy for the ongoing dynamism often accelerated by human impacts the estuary is the terminus of the murray darling catchment which covers 1 073 million km 2 of the australian continent terminal lakes alexandrina albert and the coorong lagoon are holocene features occupying tectonically subsiding quaternary interdune areas they formed in response to eustatic sea level rise following the last glacial maximum ca 20 ka the last interglacial shoreline 125 000 yr bp parallels the modern shoreline several kilometres inland dislocation of the last interglacial shoreline demonstrates ongoing tectonic subsidence as does historical seismic activity the northern half of hindmarsh island formed during last interglacial times when it was the sink for dominant longshore transport from the southeast which pushed the river murray westward partly explaining the large bend in the river murray at goolwa the modern coastal barriers of sir richard peninsula and younghusband peninsula formed from 7000 yr ago following glacier melt and sea level rise subsequently the barriers have migrated landward sporadically exposing lagoonal sediments on the ocean beaches differential loading of the soft lagoonal sediments by advancing dunes possibly in conjunction with seismic events has deformed and elevated them to up to 10 m above present sea level apsl during the mid holocene an extensive sand flat with associated dunes formed immediately inland of the coastal barrier at least six generations of late pleistocene dune systems occur in the region for example during last glacial times the climate was drier colder and windier than at present and a system of parallel west east trending yellow red desert dunes developed around the lakes aeolian processes remain important with occasionally up to 5000 tonnes of sand being in motion along 10 km of the modern shoreline during mouth migration dunes up to 2 m high have been formed and vegetated in 12 months directly inland from the mouth and replicating the formation of older dunes on hindmarsh island elsewhere sand blown directly from the barrier system infills channels barrage construction on the beach facies of the last interglacial shoreline transformed the estuary into freshwater lakes with permanently raised water levels and reduced the tidal prism by 90 increased deposition upstream and downstream accompanied barrage construction as have accelerated lakeshore erosion and the growth and consolidation of the flood tidal delta bird island these human accelerated changes provide rapidly formed analogues of older quaternary features and aid their interpretation the shape and location of the murray mouth is constantly changing migrating over 1 6 km since the 1830s migrations of up to 6 km over the past 3000 yr have influenced sedimentation on the landward shore of the back barrier lagoonal system

propagation of enso temperature signals into the middle atmosphere a comparison of two general circulation models and era 40 reanalysis data the vertical propagation of the el nino southern oscillation enso temperature signal has been analyzed in two general circulation models the whole atmosphere community climate model and the middle atmosphere european center hamburg model and in the era 40 reanalysis data set monthly mean data have been used and composite differences el nino la nina have been computed our results show that the enso signal propagates into the middle atmosphere by means of planetary rossby waves significant wave like anomalies are observed up to around 40 km this propagation is strongly influenced by the zonal mean zonal winds being most effective in midlatitudes of the northern hemisphere because enso events tend to peak in northern winter when stratospheric winds are westerly in the northern hemisphere and allow vertical propagation of rossby waves in addition zonal mean temperature anomalies are observed in the middle atmosphere in the tropics and at polar latitudes of the northern hemisphere these anomalies are the result of changes in the residual mean meridional circulation our analysis reveals that during an el nino event vertical wave propagation and divergence of eliassen palm flux are enhanced forcing a stronger residual circulation in the stratosphere which cools the tropics and warms the higher latitudes this pattern is highly significant in the models during certain months but much less in the era 40 data where other sources of variability in particular the quasi biennial oscillation also influence the residual circulation

the multi decadal morphodynamic changes of the mouth bar in a mixed fluvial tidal estuarine channel abstract inner channel mouth bars imb are common and vital geomorphological structures in estuaries that can efficiently promote the progradation of a fluvial delta however these significant structures face serious interferences by natural and human forces this study mainly focuses on imb deposited in the mixed fluvial tidal dominated south passage sp of the changjiang estuary between 1959 and 2018 to reveal how multidecadal morphodynamic variability in a mouth bar responds to natural forcing and human interferences the results show that the volume of the imb in the sp increased from 1128 106 m3 in 1959 to 1636 106 m3 in 1989 and then decreased to 462 106 m3 in 2018 meanwhile the evolution of the imb could be divided into five stages the growing phase 1959 to 1979 which showed a v shape the partial adjustment phase 1999 2003 which showed a crest dent shape the stable phase which showed a flat shape 2004 2010 the partial adjustment phase 2011 2017 when jiangyanan shola inserted into the sp and finally evolved into a flat shape in 2018 fluvial water discharge and suspended sediment discharge ssd did not control the variation in the mouth bar enso events were normally responsible for not only the periodic variations in the landward slope and the water depth of the crest of the imb but also occasional extreme changes in the imb moreover local sandbar insertion sediment from the seaside induced by strong tidal power and intensified engineering projects resulted in the continual shrinkage of the mouth bar by depositing more sediment at the mouth bar our work implies that understanding and governing this imb will bring additional economic benefits to this fast developing society but the protection of this delicate estuarine geomorphology system should still receive great attention

a geochemical evaluation of perennial spring activity and associated mineral precipitates at expedition fjord axel heiberg island canadian high arctic abstract two groups of perennial springs are observed in the canadian high arctic at expedition fjord on axel heiberg island at colour peak and gypsum hill saline discharge 1 3 2 5 molal nacl produces a variety of calcite travertine and gypsum rich precipitates saturation index calculations of the spring waters at colour peak suggest co 2 degassing from the waters causes calcite precipitation gypsum precipitation dominates at gypsum hill where spring waters have lower alkalinity and higher so 4 concentrations mineral accumulations form both channel and rimstone pool morphologies as a result of varying slope conditions at colour peak confined flow in steep slope areas develop massive structures in contrast to more friable porous accumulations in areas where waters fan out on shallower slopes these morphological variations lead to corresponding varying apparent rates of mineral precipitation mineral precipitation at gypsum hill is far less notable as a result of lower discharge rates and annual degradation by icing formation microscopic observations and geochemical analyses of the channel precipitates at colour peak reveal alternating light calcite spar and dark anhedral microcrystalline calcite combined with organic matter and non carbonate minerals laminae rimstone pools forming in lower sections of spring discharge are composed of accumulations of large euhedral calcite crystals interbedded with allochthonous inputs high concentration of dissolved solids is responsible for slow travertine precipitation rates which occurs during winter this precipitation is further retarded during summer months by the introduction of crystal growth inhibitors such as fe 3 and deposition of organic matter and soil sediments

morphological responses of an estuarine intertidal mudflat to constructions since 1978 to 2005 the seine estuary france abstract since 1834 the seine estuary france has been the site of numerous construction projects with the aim to accommodate and secure boat traffic since 1978 the increasing of the activities of le havre port located at the mouth of the estuary has accelerated the construction work rate several dykes a bridge and new port facilities have been constructed in rapid succession modifying considerably the hydrodynamic conditions which sustain a partially vegetated sandy muddy tidal flat located in the north bank of the estuary between the new port of le havre and the normandy bridge achieved in 1995 the present study deals with the morphological evolution of this zone from 1978 to 2005 the use of a low altitude remote sensing technique combined with traditional methods of ground survey and probes allow to demonstrate the impact of human activities on sedimentary and vegetation dynamics the northern mudflat of the estuary is the most affected by these human activities which surface have reduced of 62 during the last 27 years with an intensified local erosion during the last 27 months corresponding to a loss 1 250 000 m 3 of fine grained sediment at the same time the general sanding up in the channel of the zone has caused a loss of more than 31 of the tidal prism more than three quarters of which occurred during the last three years results also establish that the response times of the sedimentary or topographic readjustment to an installation depend on the extent and the nature of the construction in fact the sedimentary readjustments to an installation can be delayed by up to 10 years in the case of the seine estuary this delay is explained by a rapid succession of construction works which may occult the effect of a single installation except in the case of a dyke built perpendicular to ebb and flood currents the impacts of these installations reach a hydro sedimentary equilibrium on the level between 1 and 7 years after their completion

the salience of nonlinearities in the boreal winter response to enso north pacific and north america the prominence of nonlinearities in the response to el nino as compared to la nina to moderate el nino events as compared to extreme el ninno events and to different flavors of el nino events are analyzed using the nasa goddard earth observing system chemistry climate model in the central north pacific region where the sea level pressure response to el nino southern oscillation enso peaks nonlinearities are relatively muted in contrast changes to the east of this region i e the far northeastern pacific and to the north of this region over alaska in response to different enso phases are more clearly nonlinear and become statistically robust after more than 15 events are considered the relative prominence of these nonlinearities is related to the zonal wavenumber of the tropical precipitation response associated with these nonlinearities over the far northeastern pacific are nonlinearities in precipitation over western united states and surface temperature over northwest north america and midwestern united states in all regions at least 15 events of each type are necessary before nonlinearities can be identified as statistically significant at the 95 confidence level due to the presence of internal atmospheric variability as there have only been a similar number of enso events to the total needed for significance since 1920 it is not surprising that it has been difficult to establish statistically significant nonlinearities using observational data

multi model assessment of the late winter extra tropical response to el nino and la nina el nino southern oscillation enso is known to affect the northern hemisphere tropospheric circulation in late winter january march but whether el nino and la nina lead to symmetric impacts and with the same underlying dynamics remains unclear particularly in the north atlantic three state of the art atmospheric models forced by symmetric anomalous sea surface temperature sst patterns mimicking strong enso events are used to robustly diagnose symmetries and asymmetries in the extra tropical enso response asymmetries arise in the sea level pressure slp response over the north pacific and north atlantic as the response to la nina tends to be weaker and shifted westward with respect to that of el nino the difference in amplitude can be traced back to the distinct energy available for the two enso phases associated with the non linear diabatic heating response to the total sst field the longitudinal shift is embedded into the large scale rossby wave train triggered from the tropical pacific as its anomalies in the upper troposphere show a similar westward displacement in la nina compared to el nino to fully explain this shift the response in tropical convection and the related anomalous upper level divergence have to be considered together with the climatological vorticity gradient of the subtropical jet i e diagnosing the tropical rossby wave source in the north atlantic the enso forced slp signal is a well known dipole between middle and high latitudes different from the north atlantic oscillation whose asymmetry is not indicative of distinct mechanisms driving the teleconnection for el nino and la nina

isotope geochemistry of stratified lake a ellesmere island n w t canada ionic composition salinity temperature ph tritium and stable isotope compositions of water and ions were determined for samples collected in 1969 and 1982 from different depths of stratified lake a on ellesmere island tritium contents and ionic and stable isotope compositions were diagnostic of recent fresh water overlying older deeper trapped seawater a temperature maximum occurs at 15 m in the freshwater seawater transition zone salinity 18o and d data suggest that the lake evaporated slightly and acquired about 12 fresh water prior to stratification individual ion concentrations reveal a slightly modified cation composition and marked depletions in sulphate and enrichments in dissolved carbonate compared with modern ocean water the 34s 18o and 13c data for and attest to extensive anaerobic reduction during the lake s history

evolution of the jiuduansha wetland and the impact of navigation works in the yangtze estuary china abstract the estuarine wetlands in the yangtze estuary face increasing threats due to large scale engineering projects and huge land requirements as a wetland national nature reserve and important stopover site for migratory shorebirds of the east asian australasian flyway the jiuduansha wetland one of four main islands in the estuary is of both national and international importance since 1998 the previously undisturbed wetland has been considerably modified by the adjacent deep water navigation channel project dnc in order to understand the role of the dnc for the evolution of the jiuduansha wetland we performed a diagnostic study from multiple perspectives including deposition rate area change evolution track geometric characteristics and geomorphological change by coupling gis geostatistics and remote sensing techniques this study demonstrates the impact of the dnc on the jiuduansha wetland in a spatially explicit way multi temporal bathymetric maps and landsat images from before and after the dnc was constructed were adopted to conduct our study we find that deposition has occurred in most parts of the wetland over the past almost 30 years accounting for 67 3 of the total area however over 40 of the study area shows a decreasing trend in deposition rate the spatial distribution of deposition erosion patterns is closely linked to the dnc we also find that the dnc has substantial effects on the evolution of the jiuduansha wetland the 0 2 and 5 m isobaths in the jiuduansha shoal jds as well as in the jiangya shoal jys the upper shoal us and the middle lower shoal mls show different response patterns to the dnc specifically the south training jetty of the dnc has an adsorption effect on the jds above the 2 m isobaths intersecting with it as a result the evolution track geometric and geomorphological characteristics of the jds were markedly altered in the short term our comprehensive analysis suggests that in the future the jds will become more elongated in both the upstream and downstream direction along the south training jetty and that the south side of the jds will be eroded

calcite supersaturation and precipitation kinetics in the lower colorado river all american canal and east highline canal in situ ph determinations and analysis of major ions in solution indicated that the lower colorado river is supersaturated with respect to calcite throughout the entire daily cycle in both winter and summer although the ion activity product was 4 to 6 times greater than the calcite solubility product there was no detectable precipitation chemical analyses of water samples taken along 350 km of the river and canals from parker dam to the salton sea also revealed no evidence of calcium carbonate precipitation despite the inflow of saline and highly supersaturated irrigation return flows laboratory kinetic studies indicated that calcite crystal growth rates with colorado river water are about 30 of the rate for pure ca hco3 waters and about 70 of that for synthetic colorado river water calcite precipitation by crystal growth in the river is limited by the combination of short residence times and unavailability of reactive calcite critical supersaturation levels necessary for heterogeneous nucleation do not occur a high suspended load limits algal photosynthesis and thus prevents large decreases in daytime h2co3 levels

surface temperature patterns associated with the southern oscillation abstract the typical global and large scale regional temperature patterns associated with the low warm and high cold phases of the southern oscillation so are investigated a total of 12 separate regions were found to have consistent temperature patterns associated with low phase of the so while 11 areas were found to have temperature patterns associated with the high phase of these areas 9 have expected temperature patterns during both phases of the so in the tropics temperature anomalies are of the same sign as the so related sea surface temperature sst anomaly in all land regions except for one area in the west pacific three extratropical responses to the low phase of the so are found over north america and one is found in japan high so temperature patterns were found in the extratropies for japan western europe and northwestern north america the identified temperature responses are more consistent in tropical regions than in the extratropies the so can influence the estimation of

human impacts on the changjiang yangtze river basin china with special reference to the impacts on the dry season water discharges into the sea abstract the annual mean discharge from the upper changjiang yangtze basin has shown a significant decreasing trend since the end of the 19th century since the 1970s the monthly mean discharge to the sea has also shown a dramatic decrease during dry seasons this paper examines the human impacts on the major hydrological processes in the changjiang river basin with a special focus on their influence on the discharge from the drainage basin to the sea during the dry season climatic warming has been obvious since the 1960s in the headwater area resulting a continuous retreat of glaciers while the increased evaporation is responsible for the dropping of lake water levels and decrease in water area such a trend continuing into the coming decades will significantly change the seasonal hydrological processes especially the dry season discharges from the upper basin the decreasing vegetation cover and the increasing reservoir volume capacity also impacted on the water discharge over the past decades although in different ways the possible impacts of the three gorges dam on the monthly variation of water discharge to the sea are discussed with special emphasis in the middle basin discussions are focused on the effect of decreasing lake area of increasing reservoir capacity and of irrigated agriculture on the temporal changes of water discharge since the 1950s the human impacts on water discharge from the lower basin to the sea are mostly attributed to water transfer to both tributary and neighboring drainage basins by a large number of electric pumping stations and sluices the total water transferring capacity is more than 5000 m3 s along the lower river studies indicate that in a dry season the water discharge to the sea is greatly reduced and results in strong saltwater intrusion in the estuary

hydrogeology of the central mackenzie valley abstract more than 100 springs seeps and mineralized ponds in the central mackenzie valley have been investigated using chemistry field observations and a general knowledge of the geology in conjunction with environmental isotopes 2 h and 18 o values indicate precipitation primarily snowmelt as the source for all groundwaters sampled chemical analyses of the waters indicate that there are three major components ca 2 so 4 2 dominates followed by na cl and ca 2 mg 2 hco 3 the chemical data in combination with 34 s data indicate that the devonian bear rock formation is the major aquifer throughout the valley other important bedrock aquifers include the mt kindle franklin mountain and saline river formations recharge is directly into bedrock through solution channels or karst systems within the franklin mountains discharge from the bedrock units is controlled by fold and fault structures permafrost is a major factor controlling groundwater recharge but does not significantly affect the location of groundwater discharge

processes affecting groundwater chemistry in a zone of saline intrusion into an urban sandstone aquifer abstract samples have been collected from inflows into railway tunnels in the triassic sandstone aquifer beneath liverpool and the mersey estuary england u k these provide a profile through a saline freshwater mixing zone analyses were made of major anions and cations 34s and 18o in so4 13c in dissolved inorganic c and 87sr 86sr the data demonstrate that the presence of a low permeability fault exerts a strong control on the local groundwater chemistry on the estuary side of the fault groundwater chemistry is dominated by mixing of intruding estuary water which is modified by so4 reduction and calcite dissolution with fresh groundwater the environment of so4 reduction in the tidal estuary is one of repeated reduction and re oxidation of s in an open system and has resulted in virtually no change in s isotopic composition but an enrichment in residual so4 18o of 1 5 groundwater chemistry on the landward side of the fault is primarily the result of recharge in an urban environment there is also evidence that saline water has been present in this region of the aquifer in the past and that this has now been flushed by fresh groundwaters this saline water was either transported along the landward side of the fault from nearer the estuary or more probably transmitted across the fault both mechanisms would have been driven by large landward head gradients caused by heavy industrial abstraction earlier this century this has produced a zone of groundwaters depleted in ca and radiogenic sr and enriched in na as a result of ion exchange between the fresh groundwaters and the aquifer previously occupied by more saline water sulphur isotopic composition however shows no variation since so4 does not undergo significant ion exchange a tracer test from a borehole to the tunnels showed multiple breakthroughs to some locations indicating a number of different flow paths through the aquifer the maximum flow velocity recorded in this test was 140 m d suggesting flow along fractures

shoal morphodynamics of the changjiang yangtze estuary influences from river damming estuarine hydraulic engineering and reclamation projects abstract concerns regarding estuarine shoal morphodynamics have increased worldwide because of intensive anthropogenic activities to explore response of estuarine shoals to possible couplings of multiple artificial interferences in river basins and within estuaries the link between the morphodynamic processes of the nanhui shoal nhs which is located along the southern margin of the changjiang estuary the largest estuary in asia and river damming estuarine hydraulic engineering and reclamation projects is discerned in this study the results reveal that the nhs exhibited secular polarization during 1998 2013 with a significant accretion of 1 8 10 8 m 3 landward from the tidal ridge and an erosion of 0 3 10 8 m 3 on the seaward edge respectively forming a steep slope with an elevation between 2 and 3 m meanwhile the nhs morphodynamics could be divided into 3 stages mild accretion with an undisturbed tidal channel during 1998 2002 strong sedimentation with a disrupted tidal channel during 2003 2008 and large scale landward accretion with an infilled tidal channel after 2009 moreover the nhs s volume variations exhibited an 18 month cycle even though an increased area of 35 km 2 above 2 m and a decreased area of 45 km 2 between 2 and 5 m were observed the primary causes of theses periodic changes in the nhs s volume are determined as the fluctuating changjiang water discharge and cyclically altered hydrodynamics of the south passage the deep waterway project dwp and reclamation projects were responsible for the polarization of seaward erosion and landward accretion respectively moreover these reclamation projects dominated the staggered changes in nhs morphodynamics by inducing continuous accretion within the tidal channel compared to estuarine engineering river damming induced dramatic declines in distal sediment may have played a minor role in flat changes of nhs

rapid human induced siltation of the macro tidal ord river estuary western australia field studies on the sediment dynamics of the two arms of cambridge gulf tropical western australia were undertaken the system is macro tidal with 8 m tides the west arm is the estuary of the durack and pentecost rivers which are largely untouched by human activities the east arm is the estuary of the ord river affected by land clearing which started 100 years ago and by two river dams constructed 30 years ago prior to damming of the ord river the natural flow in all rivers was highly seasonal characterized by small at times negligible flow during the dry season which lasts eight months and occasional river floods during the wet season which lasts four months the river flow has been regulated in the east arm as a result of damming this resulted in suppressing large river floods the salinity intrusion length has decreased by about 50 in the east arm following river damming the east arm has silted measurably over the last 30 years with the stream cross sectional area decreasing by about 50 field and numerical studies suggest that this is due to the dam induced suppression of large river floods which has in turn allowed a greater amount of tidal pumping of sediment into the east arm from cambridge gulf since tidal pumping is increasing as the system is silting the east arm appears to now be geomorphologically unstable as a result of human activities numerical studies suggest it may take as little as 100 years for the ord river to reach a new equilibrium modelling suggests that this equilibrium may be characterized by a salinity intrusion length half that before damming a channel width and depth reduced by 70 and a much stronger tidal asymmetry characterized by an increasing size of the tidal bore the west arm appears to be at equilibrium since there has been no net loss or gain of sediment for the last 111 years tidal dynamics and river floods appear responsible for self scouring this channel

controls on δ 34 s and δ 18 o of dissolved sulfate in aquifers of the murray basin australia and their use as indicators of flow processes the usefulness of stable isotopes of dissolved so4 34s and 18o to study recharge processes and to identify areas of significant inter aquifer mixing was evaluated in a large semi arid groundwater basin in south eastern australia the murray basin the distinct isotopic signatures in the oxidizing unconfined murray group aquifer and the deeper reducing renmark group confined aquifer may be more sensitive than conventional chemical tracers in establishing aquifer connections 34s values in the unconfined murray group aquifer in the south and central part of the study area decrease along the hydraulic gradient from 20 8 to 0 3 the concomitant increasing so4 cl ratios as well as relatively low 18oso4 values suggest that vertical input of biogenically derived so4 via diffuse recharge is the predominant source of dissolved so4 to the aquifer further along the hydraulic gradient towards the discharge area near the river murray 34s values in the unconfined murray group aquifer increase and so4 cl ratios decrease due to upward leakage of waters from the confined renmark group aquifer which has a distinctly low so4 cl and high 34s 14 9 56 4 relatively positive 34s and 18oso4 values and low so4 cl in the renmark group aquifer is typical of so4 removal by bacterial reduction the s isotope fractionation between so4 and hs of 24 estimated for the confined aquifer is similar to the experimentally determined chemical fractionation factor for the reduction process but much lower than the equilibrium fractionation 70 even though the confined groundwater residence time is 300 ka years mapping the spatial distribution of 34s and so4 cl of the unconfined murray group aquifer provides an indicative tool for identifying the approximate extent of mixing however the poorly defined end member isotopic signatures precludes quantitative estimates of mixing fractions

holocene climatic change and the distribution of peatlands in western interior canada abstract dates of basal fen peat at 52 locations across west central canada indicate that peat deposition began 6000 yr b p basal fen peat parallels the foothills of the rocky mountains and extends eastward along 54 30 north latitude the absence of 6000 yr b p peat within this zone is attributed to a warmdry early to middle holocene climate that caused severe seasonal droughts and prevented the establishment of peat forming fen vegetation wetlands west and probably north of this line experienced lower water tables but supported fen vegetation as the climate became cooler and moister stable water tables allowed the development of fens and rapid peat accumulation ensued reaching the modern distribution of fens between 2000 and 3500 yr b p projections of climatic parameters indicate that the mean annual growing degree days were 6 to 21 higher during the early and middle holocene and that precipitation was reduced through most of the area resulting in much higher by 17 to 29 aridity than at present

barotropic wave propagation and instability and atmospheric teleconnection patterns abstract a global barotropic model linearized about the 300 mb climatological mean january flow is perturbed by applying a series of localized forcings distributed throughout the tropics and subtropics structures which resemble the observed pacific north american and east atlantic teleconnection patterns noted by wallace and gutzler 1981 tend to recur in the responses similar patterns are found to result from the dispersion of isolated initial perturbations placed at a variety of locations in the tropics and midlatitudes it is shown that these structures are related to the most rapidly growing mode associated with barotropic instability of the zonally varying climatological basic state in the absence of damping this mode has an e folding time of about a week and a period close to 50 days in localized regions the instantaneous growth rates can be competitive with those of baroclinic instability these episodes of rapid local barotropic growth are interspersed with intervals in which the local

the paint pots kootenay national park canada a natural acid spring analogue for mars1 2 the paint pots are a natural fe so4 acid spring system along the kicking horse rim a major geological feature that has controlled fluid flow and mineralization over geologic time the very low ph 3 and extremely high trace metal concentrations of the springs are anomalous and greatly exceed health limits zn 35 8 mg l pb 0 461 mg l as 82 7 ppb sulphur isotopes 34s and 18o in sulphate equal to 11 4 and 12 1 respectively are consistent with sulphide oxidation mass balance calculations indicate that the springs must have derived their acidity and metal content from natural weathering of a pyrite rich ore deposit in the vicinity several ore deposit types occur along the kicking horse rim with the mississippi valley type mvt style being the most consistent with the source of the spring waters at the spring outlet fe rich waters oxidize forming large cone features of fe o precipitates predominantly goethite a diverse microbial community has been identified in the site that is di

reconstruction of holocene changes in alpine vegetation and climate in the maligne range jasper national park alberta abstract pollen macrofossil logs and needles and oxygen isotope data from tree rings are presented for three alpine bog sites in the maligne range of the canadian rockies organic sedimentation at the watchtower site began prior to ca 9500 14 c yr b p and by 8770 yr b p timberlines were at least 100 m above present levels the two pollen records are dominated by pinus and subsequent changes in timberlines are inferred from pollen ratio data abies pinus and from macrofossils the recovered records indicate two periods of high hypsithermal timberlines ca 8800 7500 and 7200 5200 yr b p separated by a short interval ca 7300 7400 yr b p when timberline approached modern levels after ca 4500 yr b p timberlines have been similar to or lower than present reaching minimum values in the last 500 yr 18 o determinations from the cellulose of samples of 5 or 10 annual rings cut from contemporary picea englemannii at timberline show strong correlations with mean annual temperatures at jasper isotopic determinations from hypsithermal age logs recovered from sites above present timberline indicate mean annual temperatures were at least 0 5 c warmer ca 8060 and 8770 yr b p than at present at the watchtower site data from logs at the maligne pass site suggest that temperatures were about 1 2 and 1 6 c warmer ca 6000 and 5300 yr b p estimates of temperature from the pollen ratio data are more conservative and suggest maximum differences of ca 1 0 c in july temperatures over the last 8000 yr

long term morphological change and its causes in the mersey estuary nw england changes in the morphology of the mersey estuary and their possible causes have been investigated using historical trend analysis and expert geomorphological assessment historical bathymetric charts were digitised and analysed within a gis to provide quantitative estimates of changes in areas and sediment volumes above and below selected elevation planes the results show that the estuary experienced major changes over the last 150 years notably between the late 19th century and ca 1950 an analysis of data relating to possible natural and human factors which could have influenced these changes suggests that training wall construction and dredging in the outer estuary and liverpool bay was the most significant factor contributing to change during this period these activities modified the hydrodynamic and sediment transport regime in a way which enhanced an existing natural tendency for movement of sediment from liverpool bay and the outer estuary into the inner estuary changes in other factors including sea level tidal range wind wave climate freshwater flow and embanking land reclamation were of relatively minor importance between 1950 and 1977 the rate of sediment accumulation in the inner estuary declined as the estuary approached a new condition of dynamic equilibrium and since 1977 there has been a slight net loss of sediment under these conditions the changes in natural forcing factors such as sea level and storminess are likely to have a relatively greater effect on the estuary than in the past

sulfur isotope signatures in gypsiferous sediments of the estancia and tularosa basins as indicators of sulfate sources hydrological processes and microbial activity abstract in order to reconstruct paleo environmental conditions for the saline playa lakes of the rio grande rift we investigated sediment sulfate sources using sulfur isotope compositions of dissolved so 4 2 ions in modern surface water groundwater and so 4 2 precipitated in the form of gypsum sediments deposited during the pleistocene and holocene in the tularosa and estancia basins the major sulfate sources are lower and middle permian marine evaporites 34s of 10 9 14 4 but the diverse physiography of the tularosa basin led to a complex drainage system which contributed sulfates from various sources depending on the climate at the time of sedimentation as inferred from sulfur isotope mass balance constraints weathering of sulfides of magmatic hydrothermal and sedimentary origin associated with climate oscillations during last glacial maximum contributed about 35 50 of the sulfates and led to deposition of gypsum with 34s values of 1 2 to 2 2 which are substantially lower than permian evaporates in the estancia basin microbial sulfate reduction appears to overprint sulfur isotopic signatures that might elucidate past groundwater flows a rayleigh distillation model indicates that about 3 18 of sulfates from an inorganic groundwater pool 34s of 12 6 13 8 have been metabolized by bacteria and preserved as partially to fully reduced sulfur bearing minerals species elemental sulfur monosulfides disulfides with distinctly negative 34s values 42 3 to 20 3 compared to co existing gypsum 3 8 to 22 4 for the tularosa basin microbial sulfate reduction had negligible effect on 34s value of the gypsiferous sediments most likely because of higher annual temperatures 15 33 c and lower organic carbon content median 0 09 in those sediments leading to more efficient oxidation of h2s and or smaller rates of sulfate reduction compared to the saline playas of the estancia basin 5 28 c median 0 46 of organic carbon the white sands region of the tularosa basin is frequently posited as a hydrothermal analogue for mars high temperatures of groundwater 33 3 c and high 18o h2o values 1 1 in white sands however are controlled predominantly by seasonal evaporation rather than the modern influx of hydrothermal fluids nevertheless it is possible that some of the geochemical processes in white sands such as sulfide weathering during climate oscillations and upwelling of highly mineralized waters might be considered as valid terrestrial analogues for the sulfate cycle in places such as meridiani planum on mars

controlling processes in a caco3 precipitating stream in huanglong natural scenic district sichuan china abstract huanglong scenic district is well known for its unusual and diversified landforms such as travertine pools travertine falls and travertine flows these landforms resulting from high altitude surface cold water caco 3 precipitation were chosen by unesco in 1994 as an entry in the world s nature heritage huanglong is a pristine region where there are limited human activities water analyses and thin section glass slide precipitation experiments were conducted to determine the aqueous processes controlling caco 3 precipitation and travertine landform formation results from the travertine flow indicate that the concentrations of hco 3 ca 2 and h decrease regularly along the flow paths chemical equilibrium modeling results demonstrate the importance of co 2 out gassing and caco 3 precipitation processes co 2 out gassing and caco 3 precipitation increase with increasing flow velocities in the pool area varying hydrodynamics are the primary factors which determine the extent of processes such as advection and diffusion and hence also control caco 3 precipitation and co 2 out gassing when the pool water circulation is very slow the ph of water flowing over the travertine dams increases significantly approximately 0 15 ph units downstream when the circulation is relatively fast the ph of stream water initially decreases followed by an increase of approximately 0 21 ph units as it flows past the travertine pool dams in both cases the ph rise is caused by sudden changes in the hydrodynamics of the pools despite the different initial flow conditions pool development is a consequence of spatial variations in ph which provide different conditions for caco 3 precipitation inside the travertine dam where less precipitation or even dissolution occurs compared to conditions at the top and downstream side of the dams precipitation experiments demonstrate that the top and downstream side of travertine dams are the locations of the most active precipitation particularly for pools having faster circulation precipitation experiments also reveal that vaterite a rare polymorph of caco 3 co precipitates with calcite in milky opalescent water near the upstream input portion of the pool groups thin sections covered by algae at the bottom of pools have 40 less caco 3 precipitation than those not covered by algae sem photographs of the surface of natural travertine deposits show that biofilms with diatom minimize caco 3 precipitation and that diatom adhered calcite surfaces show signs of etching suggesting that calcite dissolution may be aided by diatoms

river flow control on intertidal mudflat sedimentation in the mouth of a macrotidal estuary abstract the objective of this study is to analyze the impact of hydrological variability influenced by climatic phenomena upon the sedimentary exchange between the turbidity maximum tm and a river mouth intertidal mudflat this study carried out over a period of 10 years 1997 2006 in the seine estuary france is specifically focused on two extreme periods a wet one from 2001 to 2002 and a drier one from 2005 to 2006 this study is based on an original approach combining data gathered via low altitude remote sensing with altimeter readings and ground level measurements during this 10 year period we observed a link between climate change and the sedimentary processes on the mudflat surface the modifications of sedimentary processes are mainly connected to the multiannual variability of hydrological flow rates that control the positioning of the turbidity maximum the source of the sedimentary material deposited in this intertidal zone the tm at the mouth of the seine estuary is well developed its maximum mass is estimated to be between 300 000 tons and 500 000 tons avoine et al 1981 with maximum concentrations in the surface waters ranging from 1 to 2 g l 1 le hir et al 2001 most of the fine particles stored within the tm have been found to originate from within the catchment area dupont et al 1994 in the seine estuary the dynamics of the estuarine tm in response to hydrodynamic forcings have been previously described avoine et al 1981 and modeled e g brenon and le hir 1999 le hir et al 2001 the tm is upstream of the northern mudflat when the river flow is low

long term morphological change in the ribble estuary northwest england morphological change in the ribble estuary northwest england has been studied using bathymetric charts topographical surveys and remote sensing data a sediment budget has been prepared from the analysis of these data the results reveal a net accretional trend over the last 150 years the main channels experienced major infilling sediment also accumulated in higher parts of the intertidal zone salt marshes and sand banks while the sediment volume in the lower intertidal zone remained essentially the same there were both zones of net erosion and deposition in the outer estuary with a small net gain in subtidal sediment volume infilling associated with major morphological change was accelerated in the nineteenth century and early twentieth century principally as a result of human activities the triggering factors for increased sedimentation were embankment construction and reclamation after 1810 which progressively reduced the intertidal area tidal prism and current velocities within the estuary additionally construction of a trained channel between 1847 and 1910 to secure navigation and maintenance of this channel by dredging concentrated the ebb flow in this overdeepened channel and reduced periodic scour over the sand banks on both sides enhancing sedimentation thus the effects of human activities have outstripped those of changes in natural forcing factors on the morphological development in the area

sediment transport and trapping in marsh systems implications of tidal flux studies although the concept that marshes act as major sediment sinks may be accurate when viewing them over the last few millennia tidal transport studies suggest considerable variability with most marshes presently exporting material on an annual basis high salinity marshes along the mid atlantic coast of the united states appear to be losing 1 2 kg m 2 yr 1 while submerged upland marshes on the delmarva peninsula are eroding at rates of up to 14 kg m 2 yr 1 by comparison at least one deltaic marsh on the dutch coast along with several estuarine marshes appear to be accumulating sediment in order to assess the trapping ability of marshes in large estuaries we constructed a sediment budget for chesapeake bay which included a variety of wetland types calculations indicate that estuarine marshes trap 5 11 of the annual chesapeake bay sediment input or about one half that previously estimated it appears that most sedimentation in estuaries and perhaps other coastal systems occurs in subtidal flats below the limit of emergent marsh vegetation as mud flats become vegetated and estuarine infilling proceeds there may be a tendency for tidal currents to become ebb dominated which promotes a net export of particulates the extent to which major storm events are capable of returning enough material to balance the long term accretionary budget of tidal marshes and keep them abreast of rising sea level is open to question differences in tidal dynamics seasonal changes in sea levels and higher temperatures may help explain why in the u s southern marshes are more susceptible to export and eventual erosion than northern marshes we hypothesize that another factor the recent reductions of terrigenous sediment inputs from the southern river systems of the u s may also be critical sediment starvation may have led to undernourishment of wetland systems of the coastal zone over the last half century which may be reflected in the net export measured in the tidal marshes in this region furthermore we postulate that changes in sediment inputs are more important than eustatic sea level rise in causing the past losses of marshes which are now undergoing mass erosion thus future wetland survival will depend as much as particulate inputs to the coastal zone as on the prospects of a global rise in sea level and more efforts should be made to quantify the sediment budgets of tidal marshes

dynamics of the enso teleconnection and nao variability in the north atlantic european late winter abstractthe winter extratropical teleconnection of el nino southern oscillation enso in the north atlantic european nae sector remains controversial concerning both the amplitude of its impact

travertine mounds of the cave and basin national historic site banff national park the cave and basin national historic site is a fan shaped travertine deposit associated with four thermal spring outlets tentative age dating of the travertine mound indicates growth initiated with onset of the late holocene shift to more humid and cool climate conditions and suggests that the flow of thermal waters was limited during the hypsithermal which in turn places constraints on the evolutionary biology of endemic species in the spring system two large caves and one collapsed cave structure are developed within the deposit cave development is in response to both physical erosion of till underlying the travertine and acid gas attack of calcite that makes up the deposit this process is buffered by formation of reaction crusts of gypsum on the interior cave walls only minor modern travertine growth occurs due to historic flow control measures understanding the flow of water through the historic site is critical for long term preservation

el nino modoki and its possible teleconnection 1 using observed data sets mainly for the period 1979 2005 we find that anomalous warming events different from conventional el nino events occur in the central equatorial pacific this unique warming in the central equatorial pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly ssta on both sides along the equator empirical orthogonal function eof analysis of monthly tropical pacific ssta shows that these events are represented by the second mode that explains 12 of the variance since a majority of such events are not part of el nino evolution the phenomenon is named as el nino modoki pseudo el nino modoki is a classical japanese word which means a similar but different thing the el nino modoki involves ocean atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution analogous to the southern oscillation in the case of el nino hence the total entity is named as el nino southern oscillation enso modoki the enso modoki events significantly influence the temperature and precipitation over many parts of the globe depending on the season the impacts over regions such as the far east including japan new zealand western coast of united states etc are opposite to those of the conventional enso the difference maps between the two periods of 1979 2004 and 1958 1978 for various oceanic atmospheric variables suggest that the recent weakening of equatorial easterlies related to weakened zonal sea surface temperature gradient led to more flattening of the thermocline this appears to be a cause of more frequent and persistent occurrence of the enso modoki event during recent decades

the generation of global rotational flow by steady idealized tropical divergence abstract tropical convective heating is balanced on the large scale by the adiabatic cooling of ascent the horizontal divergence of the wind above this heating may be viewed as driving the upper tropospheric rotational wind field a vorticity equation model is used to diagnose this relationship it is shown that because of the advection of vorticity by the divergent component of the flow the rossby wave source can be very different from the simple fd source often used in particular an equatorial region of divergence situated in easterly winds can lead to a rossby wave source in the subtropical westerlies where it is extremely effective this part of the source can be relatively insensitive to the longitudinal position of the equatorial divergence a divergence field which is asymmetric about the equator can lead to a quite symmetric rossby wave source for a steady frictionless flow the rossby wave source averaged over regions within closed streamfunction or absolute vorticity contours is under cert

travertines depositional morphology and the bacterially constructed constituents abstract investigation of travertine accumulations throughout central italy and the west central u s has shown that the carbonate is precipitated in response to both inorganic and organic processes individual deposits range up to 85 m thick and hundreds of square kilometers in areal extent all of the carbonate is low magnesian calcite water chemistry temperature and morphology of the accumulation greatly influence the constituents comprising these deposits harsh environmental situations favor inorganic deposits while increasingly more moderate conditions result in the formation of a greater abundance of organically precipitated material morphological variations of travertine deposits recognized include 1 waterfall or cascade 2 lake fill 3 sloping mound fan or cone 4 terraced ound and 5 fissure ridge gross morphology internal stratification and constituents comprising these deposits vary systematically depending upon the type of accumulation and chemistry of the waters bacterially precipitated calcite forms a large percentage of the carbonate in many travertine accumulations exceeding 90 of the framework grains comprising some of the lake fill deposits bacteria are among the first taxa to inhabit and reproduce in harsh spring environments and produce a variety of fascinating constituents the bacteria are primarily rods generally 0 2 m in diameter and less than 1 0 m in length the rods readily decay resulting in calcite crystals loaded with micropores the basic building block of bacterially constructed travertine is a clump of bacteria averaging 20 m in diameter enclosed in a single crystal of calcite aggregates of these crystals produce a variety of deposits including 1 crudely laminated carbonate mud 2 finely laminat d layers of mud 3 intraclasts 4 foam rock and 5 shrubs the shrubs are most striking commonly forming layers 1 3 cm thick but also producing bacterial pisoids at some locales bacterial stromatolites composed of layers of shrubs alternating with finely laminated layers of bacterial mud comprise essentially the entire deposit the shrub layers are the result of flourishing summer growth of bacteria and furthermore show remarkable daily laminae 0 1 0 5 mm thick the importance of bacteria in the formation of travertine and their universally recognized abundance in modern sediments provides an impetus for a reexamination of the role of bacteria in the origin of other types of ancient deposits

anomalous winter climate conditions in the pacific rim during recent el nino modoki and el nino events present work compares impacts of el nino modoki and el nino on anomalous climate in the pacific rim during boreal winters of 1979 2005 el nino modoki el nino is associated with tripole dipole patterns in anomalies of sea surface temperature precipitation and upper level divergent wind in the tropical pacific which are related to multiple boomerangs of ocean atmosphere conditions in the pacific zonal and meridional extents of those boomerangs reflect their independent influences which are seen from lower latitudes in the west to higher latitudes in the east in the central pacific more moisture is transported from the tropics to higher latitudes during el nino modoki owing to displacement of the wet boomerang arms more poleward toward east discontinuities at outer boomerang arms manifest intense interactions between tropical and subtropical extratropical systems the pacific north american pattern and related climate anomalies in north america found in earlier studies are modified in very different ways by the two phenomena the seesaw with the dry north and the wet south in the western usa is more likely to occur during el nino modoki while much of the western usa is wet during el nino the moisture to the southwestern usa is transported from the northward shifted itcz during el nino modoki while it is carried by the storms traveling along the southerly shifted polar front jet during el nino the east asian winter monsoon related anticyclone is over the south china sea during el nino modoki as compared to its position over the philippine sea during el nino causing opposite precipitation anomalies in the southern east asia between the two phenomena

use of lacustrine sedimentary sequences as indicators of holocene glacial history banff national park alberta canada abstract bottom sediments from three lakes in the canadian rocky mountains were examined with the aim of evaluating the usefulness of downvalley sediment studies in reconstruction of holocene glacial histories analyses of organic carbon and carbonate contents of core sediments provide information on changing sedimentation rate and changing relative importance of glacial and non glacial sediment sources sedimentary histories of the three lakes are similar suggesting that they record regional glacial climatic forcing rather than localized events and thus that they may be useful in reconstructing holocene glacial history lacustrine sediments indicate a period of high sedimentation rates and relatively large glacial sediment contribution prior to 7500 7000 yr b p with much reduced rates and decreased glacial sediment contribution between about 6000 and 4000 yr b p possibly interrupted by a brief period of increased glacial sediment output shortly after 5000 yr b p sometime after 4000 yr b p sedimentation rates and glacial sediment output began to rise again reaching approximately present levels by 2750 2650 yr b p and have not since returned to low mid holocene levels in detail over the last 3000 yr there is some indication of a slight decrease in sedimentation rate for more than 1000 yr after about 2200 yr b p sedimentation rates and glacial sediment input into all three lakes rose between about 900 and 750 yr b p and have remained very high since if the lake sediments are interpreted as a proxy record of upvalley glacial activity they allow the development of a glacial chronology which is at once generally consistent with and more complete and easily datable than the surficial glacial record

neoglacial glacier fluctuations in the canadian rockies abstract the little ice age was the most extensive neoglacial glacier advance in the canadian rockies evidence of earlier less extensive neoglacial glacier advances is based on wood recovered from several glacier forefields wood flushed out of athabasca glacier 7550 8230 yr b p three dates and dome glacier 6120 6380 yr b p two dates indicates that forests occurred upvalley of present glacier termini during the hypsithermal detrital logs from peyto 14 dates saskatchewan 3 dates robson 3 dates and yoho 1 date glaciers plus in situ slumps at peyto and robson glaciers have yielded 14 c dates between 2490 and 3300 yr b p 12 dates between 2800 and 2990 this wood is derived from sources at or upvalley from present glacier termini and represents forests overridden by glaciers between ca 3100 and 2500 yr b p treeline was higher than present immediately prior to this advance this advance which did not extend beyond the little ice age maximum position is designated the peyto advance and correlated with the tiedemann advance in western british columbia earliest little ice age advances at peyto and robson glaciers are dated ca 800 600 yr b p at positions ca 500 m upvalley from little ice age limits

el nino la nina and the nonlinearity of their teleconnections the paradigm of an atmospheric system varying linearly with respect to extreme phases of the el nino southern oscillation is questioned it is argued that the global response to tropical pacific sea surface temperature forcing will be inherently nonlinear a physical basis for this intrinsic nonlinearity is the thermodynamic control on deep convection climate statistics for warm and cold events of the tropical pacific are analyzed separately for the northern winter periods during 1950 96 composite analysis of 500 mb heights reveal planetary scale teleconnection patterns as noted in earlier studies a new result is the evidence for an appreciable 358 longitude phase shift between the warm and cold event circulation composites and the two wave trains appear to have different tropical origins a large nonlinear component in north american surface climate anomalies is also found which is consistent with such a phase shift in teleconnections in the tropics rainfall anomalies also show evidence of nonlinear behavior the maximum rain anomalies along the equator are located east of the date line during warm events but west of the date line during cold events the interpretation of this behavior is complicated however by the fact that composite warm event sst anomalies are not the exact inverse of their cold event counterparts idealized atmospheric general circulation model agcm experiments are performed in order to test the question of whether the observed nonlinearity is an intrinsic property of the atmospheric system the model is forced with a composite sst anomaly that undergoes a realistic seasonally varying enso life cycle as described by e rasmusson and t carpenter both positive and negative phases of the sst anomaly are used and a 40 member ensemble of warm and cold event model simulations is conducted a nonlinear climate response in the agcm is found that closely resembles the observed composites including a shift in the equatorial positions of the maxmium rain responses and a phase shift of teleconnection patterns in the upper troposphere barotropic model experiments indicate that the inherent nonlinearity in the tropical rain response may itself be responsible for the phase shift in the extratropical teleconnection patterns

analysis of the nonlinearity of el nino southern oscillation teleconnections abstractel nino southern oscillation enso has significant variations and nonlinearities in its pattern and strength enso events vary in their position along the equator with some located in the central pacific cp and others in the east pacific ep to study how these variations are reflected in global enso teleconnections both observations and idealized atmospheric general circulation model agcm simulations are analyzed clear nonlinearities exist in observed teleconnections of sea level pressure slp and precipitation however it is difficult to distinguish if these are caused by the different signs strengths or spatial patterns of events strong el nino events mostly being ep events and strong la nina events mostly being cp events or by combinations of these therefore sensitivity experiments are performed with an agcm forced with idealized ep and cp enso sea surface temperature sst patterns with varying signs and strengths the response is generally stronger for warm events than for c

extra tropical atmospheric response to enso in the cmip5 models the seasonal mean extra tropical atmospheric response to el nino southern oscillation enso is assessed in the historical and pre industrial control cmip5 simulations this analysis considers two types of el nino events characterized by positive sea surface temperature sst anomalies in either the central equatorial pacific cp or eastern equatorial pacific ep as well as ep and cp la nina events characterized by negative sst anomalies in the same two regions seasonal mean geopotential height anomalies in key regions typify the magnitude and structure of the disruption of the walker circulation cell in the tropical pacific upper tropospheric enso teleconnections and the polar stratospheric response in the cmip5 ensembles the magnitude of the walker cell disruption is correlated with the strength of the mid latitude responses in the upper troposphere i e the north pacific and south pacific lows strengthen during el nino events the simulated responses to el nino and la nina have opposite sign the seasonal mean extra tropical upper tropospheric responses to ep and cp events are indistinguishable the enso responses in the merra reanalysis lie within the model scatter of the historical simulations similar responses are simulated in the pre industrial and historical cmip5 simulations overall there is a weak correlation between the strength of the tropical response to enso and the strength of the polar stratospheric response enso related polar stratospheric variability is best simulated in the high top subset of models with a well resolved stratosphere