the relationship of weddell polynya and open ocean deep convection to the southern hemisphere westerlies abstractthe weddell polynya of the mid 1970s is simulated in an energy balance model ebm sea ice ocean coupled general circulation model gcm with an abrupt 20 increase in the intensity of southern hemisphere sh westerlies this small upshift of applied wind stress is viewed as a stand in for the stronger zonal winds that developed in the mid 1970s following a long interval of relatively weak zonal winds between 1954 and 1972 following the strengthening of the westerlies in this model the cyclonic weddell gyre intensifies raising relatively warm weddell sea deep water to the surface the raised warm water then melts sea ice or prevents it from forming to produce the weddell polynya within the polynya large heat loss to the air causes surface water to become cold and sink to the bottom via open ocean deep convection thus the underlying layers cool down the warm water supply to the surface eventually stops and the polynya cannot be maintained anymore during the 100 yr long model simulation

greenland meltwater as a significant and potentially bioavailable source of iron to the ocean the micronutrient iron is thought to limit primary production in large regions of the global ocean meltwater measurements suggest that the greenland ice sheet serves as a significant source of potentially bioavailable iron to the surrounding coastal ocean

enrichment and fractionation of rare earth elements in fes and organic rich estuarine sediments receiving acid sulfate soil drainage abstract an understanding of processes controlling the behaviour of rare earth elements rees within estuarine sediments is essential for the effective use of rees as tracers of environmental conditions this study investigates the enrichment and fractionation of rees in sediments with abundant iron monosulfides fes measured as acid volatile sulfide median 156 mol g and organic carbon median 3 2 mmol g we examined sediments collected from a eutrophic estuary in western australia which comprised several sedimentary environments including sites receiving drainage from acid sulfate soils ass in general sediment bound rees were highly soluble in hcl with 1 mol l hcl extractable ree concentrations amounting to 80 of corresponding total concentrations in approximately 70 of samples a mid ree mree enrichment was consistently apparent in all sediment samples with a median mree enrichment value of 1 30 range 1 13 1 50 for the total ree concentrations and 1 26 range 1 17 1 44 in the 1 mol l hcl extractions also a ce anomaly was consistently observed in the sediments examined here with a median value of 1 11 range 0 79 1 58 for the total ree concentrations and 1 19 range 1 04 1 71 in the 1 mol l hcl extracts in general a minor depletion of heavy rees hrees relative to light rees lrees was also apparent in many of the sediments yb la

geostrophic transport in the benguela current region historical data from the region between the greenwich meridian and the african continental shelf are used to compute the offshore geostrophic transport of the benguela current at 32 s the benguela current is located near the african coast transporting about 21 sv 1 sv 106 m3 s 1 of surface water toward the north relative to a potential density surface lying between the upper branch of circumpolar deep water and the north atlantic deep watar two warm core eddies of probable agulhas current origin an observed west of the benguela current at 32 s near 30 s the benguela current turns toward the northwest and begins to separate from the eastern boundary it carries about 18 sv of surface water across 28 s the current then turns mainly toward the west to flow over a relatively deep segment of the walvis ridge south of the valdivia bank a surface current with northward surface of about 10 cm s 1 flows along the western side of the valdivia bank while another northward surface current flows at about 20 cm s 1 some 300 km west of the bank about 3 sv of surface now do not leave the cape basin south of the vaidivia bank but instead drift northward as a wide sluggish flow out of the northern end of the cape basin because of the more southerly seaward extensions of most of the benguela current there are no deep reaching interactions observed between this current and the cyclonic gyre in the angola basin east of the greenwich meridian beneath the surface layer about 4 5 sv of antarctic intermediate water are carried northward across 32 and 28 s by the benguela current essentially all of which turns westward to cross the greenwich meridian south of 24 s

what caused the significant increase in atlantic ocean heat content since the mid 20th century as the upper layer of the world ocean warms gradually during the 20th century the inter ocean heat transport from the indian to atlantic basin should be enhanced and the atlantic ocean should therefore gain extra heat due to the increased upper ocean temperature of the inflow via the agulhas leakage consistent with this hypothesis instrumental records indicate that the atlantic ocean has warmed substantially more than any other ocean basin since the mid 20th century a surface forced global ocean ice coupled model is used to test this hypothesis and to find that the observed warming trend of the atlantic ocean since the 1950s is largely due to an increase in the inter ocean heat transport from the indian ocean further analysis reveals that the increased inter ocean heat transport is not only caused by the increased upper ocean temperature of the inflow but also and more strongly by the increased agulhas current leakage which is augmented by the strengthening of the wind stress curl over the south atlantic and indian subtropical gyre

abundance and fractionation patterns of rare earth elements in streams affected by acid sulphate soils abstract the abundance and shale normalised fractionation patterns of rare earth elements rees were studied in 121 streams of first and second order in an area where acid sulphate soils developed on oxidised sulphide bearing marine sediments are abundant during high water flow events in autumn on which this study focuses the leaching of rees from the acid sulphate soils is extensive resulting in high total ree concentrations up to 1 mg l in streams draining such soils exclusively in these streams there is a general depletion of the heavy rees explained by preferential scavenging of the latter by oxyhydroxides in the deepest soil profile horizons in streams draining areas of glacial till and peat the ree concentrations are several orders of magnitude lower in these streams in contrast to the ree enriched streams there is a depletion of light rees explained most likely by preferential complexation of the middle and heavy rees by dissolved humic substances

biogeographical patterns and environmental controls of phytoplankton communities from contrasting hydrographical zones of the labrador sea the labrador sea is an important oceanic sink for atmospheric co2 because of intensive convective mixing during winter and extensive phytoplankton blooms that occur during spring and summer therefore a broad scale investigation of the responses of phytoplankton community composition to environmental forcing is essential for understanding planktonic food web organisation and biogeochemical functioning in the labrador sea here we investigated the phytoplankton community structure 4 m from near surface blooms 1 2 mg chla m 3 occurred on and near the shelves in may and in offshore waters of the central labrador sea in june due to haline and thermal stratification respectively sea ice related fragilariopsis cylindrus and f oceanica and arctic diatoms fossula arctica bacterosira bathyomphala and thalassiosira hyalina dominated the relatively cold 0 c and fresh salinity 33 waters over the labrador shelf e g on the southwestern side of the labrador sea where sea ice melt and arctic outflow predominates on the northeastern side of the labrador sea intense blooms of the colonial prymnesiophyte phaeocystis pouchetii and diatoms such as thalassiosira nordenskioeldii pseudo nitzschia granii and chaetoceros socialis occurred in the lower nutrient waters nitrate 3 6 m of the west greenland current the central labrador sea bloom occurred later in the season june and was dominated by atlantic diatoms such as ephemera planamembranacea and fragilariopsis atlantica the data presented here demonstrate that the labrador sea spring and early summer blooms are composed of contrasting phytoplankton communities for which taxonomic segregation appears to be controlled by the physical and biogeochemical characteristics of the dominant water masses

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

last glacial maximum to holocene sea surface conditions at umnak plateau bering sea as inferred from diatom alkenone and stable isotope records 1 the bering sea gateway between the pacific and arctic oceans impacts global climate when glacial interglacial shifts in shore line position and ice coverage change regional albedo previous work has shown that during the last glacial termination and into the holocene sea level rises and sea ice coverage diminishes from perennial to absent yet existing work has not quantified sea ice duration or sea surface temperatures sst during this transition here we combine diatom assemblages with the first alkenone record from the bering sea to provide a semiquantitative record of sea ice duration sst and productivity change since the last glacial maximum lgm during the lgm diatom assemblages indicate that sea ice covered the southeastern bering sea perennially at 15 1 cal ka b p the diatom assemblage shifts to one more characteristic of seasonal sea ice and alkenones occur in the sediments in low concentrations deglaciation is characterized by laminated intervals with highly productive and diverse diatom assemblages and inferred high coccolithophorid production at 11 3 cal ka b p the diatom assemblage shifts from one dominated by sea ice species to one dominated by a warmer water north pacific species simultaneously the sst increases by 3 c and the southeastern bering sea becomes ice free year round productivity and temperature proxies are positively correlated with independently dated records from elsewhere in the bering sea the sea of okhotsk and the north pacific indicating that productivity and sst changes are coeval across the region

observations inferences and mechanisms of the atlantic meridional overturning circulation a review this is a review about the atlantic meridional overturning circulation amoc its mean structure temporal variability controlling mechanisms and role in the coupled climate system the amoc plays a central role in climate through its heat and freshwater transports northward ocean heat transport achieved by the amoc is responsible for the relative warmth of the northern hemisphere compared to the southern hemisphere and is thought to play a role in setting the mean position of the intertropical convergence zone north of the equator the amoc is a key means by which heat anomalies are sequestered into the ocean s interior and thus modulates the trajectory of climate change fluctuations in the amoc have been linked to low frequency variability of atlantic sea surface temperatures with a host of implications for climate variability over surrounding landmasses on intra annual timescales variability in amoc is large and primarily reflects the response to local wind forcing meridional coherence of anomalies is limited to that of the wind field on interannual to decadal timescales amoc changes are primarily geostrophic and related to buoyancy anomalies on the western boundary a pacemaker region for decadal amoc changes is located in a western transition zone along the boundary between the subtropical and subpolar gyres decadal amoc anomalies are communicated meridionally from this region amoc observations as well as the expanded ocean observational network provided by the argo array and satellite altimetry are inspiring efforts to develop decadal predictability systems using coupled atmosphere ocean models initialized by ocean data

experimental studies of ree fractionation during water mineral interactions ree release rates during apatite dissolution from ph 2 8 to 9 2 rare earth elements ree release rates were measured during the open system dissolution of natural apatite at 25 c 2 8 ph 9 2 and at ionic strengths ranging from 0 001 to 0 02 mol kg all inlet solutions were ca ree and p free in agreement with previous studies apatite dissolution rates determined from outlet solution ca concentrations decrease monotonically with increasing ph outlet solution molar ree ca ratios differ from that of the dissolving apatite during the experiments this behaviour is interpreted to stem from dissolution or precipitation of minor quantities of rhabdophane ree po4 nh2o this interpretation is supported by solute speciation calculations which indicate that ree are retained in the solid phase when the outlet fluids are supersaturated with respect to nd rhabdophane ksp 10 24 5 0 5 but preferentially released when the outlet fluids are undersaturated with respect to nd rhabdophane the relative concentrations of the ree in the outlet solutions suggest that the secondary rhabdophane is slightly enriched in light ree ce to eu the results of this study suggest that rhabdophane dissolution and precipitation during apatite fluid interaction plays a major role in controlling surface and ground water ree signatures

geochemistry of the rare earth elements in hypersaline and dilute acidic natural terrestrial waters complexation behavior and middle rare earth element enrichments rare earth element ree speciation was modelled in acid 2 9 ph 3 5 hypersaline groundwaters from australia and from the palo duro basin in texas usa using a combined specific ion interaction pitzer model and ion pairing model the free metal ion species i e ln3 is the dominant form of dissolved rees in these systems accounting for 40 70 of the dissolved metal in groundwater from lake tyrrell victoria australia 50 90 of the rees in groundwater from lake gilmore western australia and always 90 of each ree in the texas groundwaters lakes tyrrell and gilmore are actually dry lakes that act as groundwater discharge zones the abundance of the free metal ion species increases in these waters with increasing ionic strength and with decreasing ph the free metal ion species is followed in abundance by ree sulfate and ree chloride complexes that account for 20 50 and 10 15 respectively of the dissolved rees in the groundwaters from lake tyrrell 15 30 and 5 20 respectively in the groundwaters from lake gilmore and 3 and 7 respectively in the palo duro basin groundwaters the groundwaters of the lake tyrrell system and the palo duro basin are enriched in the middle rees mrees compared to both the light rees lrees and the heavy rees hrees only nd sm and dy were determined in the lake gilmore groundwaters and consequently it is unclear whether these acid groundwaters are also enriched in the mrees previous investigators suggested that fe rich organic flocs ree phosphate complexation and solid liquid exchange reactions between terrestrial waters and mree enriched surface fe mn coatings suspended particulates or secondary mineral phases within aquifer materials may promote the development of mree enrichments in natural waters we propose that organic colloids and ree phosphate complexes are insignificant in acidic natural waters in regards to mree enrichments instead solid liquid exchange reactions or dissolution of surface coatings suspended particulates and or secondary phases as well as sulfate complexation more likely controls the development of mree enrichments in acidic natural terrestrial waters

temporal variability of the meridional overturning circulation at 34 5 s results from two pilot boundary arrays in the south atlantic data from two boundary arrays deployed along 34 5 s are combined to produce the first continuous in situ time series observations of the basin wide meridional overturning circulation moc in the south atlantic daily estimates of the moc between march 2009 and december 2010 range between 3 sv and 39 sv 1 sv 106 m3 s 1 after a 10 day low pass filter is applied much of the variability in this 20 month record occurs at periods shorter than 100 days approximately two thirds of the moc variability is due to changes in the geostrophic baroclinic plus barotropic volume transport with the remainder associated with the direct wind forced ekman transport when low pass filtered to match previously published analyses in the north atlantic the observed temporal standard deviation at 34 5 s matches or somewhat exceeds that observed by time series observations at 16 n 26 5 n and 41 n for periods shorter than 20 days the basin wide moc variations are most strongly influenced by ekman flows while at periods between 20 and 90 days the geostrophic flows tend to exert slightly more control over the total transport variability of the moc the geostrophic shear variations are roughly equally controlled by density variations on the western and eastern boundaries at all time scales captured in the record the observed time mean moc vertical structure and temporal variability agree well with the limited independent observations available for confirmation

the role of oscillating southern hemisphere westerly winds global ocean circulation abstractin the framework of a sea ice ocean general circulation model coupled to an energy balance atmospheric model an intensity oscillation of southern hemisphere sh westerly winds affects the

light rare earth elements enrichment in an acidic mine lake lusatia germany abstract the distribution of rare earth elements ree was investigated in the acidic waters lake and groundwater of a lignite mining district germany the fe and so4 rich lake water ph 2 7 displays high ree contents e g la 70 g l ce 160 g l and an enrichment of light ree lree in the nasc normalised pattern considering the hydrodynamic model and geochemical data the lake water composition may be calculated as a mixture of inflowing quaternary and mining dump groundwaters the groundwater of the dump aquifer is lree enriched nevertheless the leachates of dump sediments generally have low ree contents and display flat nasc normalised patterns however geochemical differences and ree pattern in undisturbed lignite lree enriched pattern and low water soluble ree contents and the weathered lignite of the dumps flat ree pattern and high water soluble ree contents suggest that lignite is probably the main ree source rock for the lake water

the impact of horizontal resolution of density field on the calculation of the atlantic meridional overturning circulation at 34 s the atlantic meridional overturning circulation and meridional heat transport hereafter the amoc and mht at 34 s as simulated by global 1 16 eddy rich henceforth glob16 and eddy permitting glob4 models are compared with observational estimates three different methods are used for calculating the modeled amoc the first method mocmod is based on simulated velocity fields while the second mocob relies on the same assumptions as available observed derived estimates the third method mocob2 is also based on hydrostatic and geostrophic relationships but relative to a barotropic circulation instead of the definition of velocity at a specific reference depth all methods correctly reproduce the time mean glob16 amoc strength but the value of the non ekman component of the glob16 amoc is only about 75 of the observed derived estimate the glob16 mht is also significantly less than observation value slightly more than 60 of the observed however the mean amoc and mht values at 34 s obtained with coarser resolution glob4 model are comparable with the observed derived estimates possible causes for the differences between the eddy rich model and observational data are studied it is shown that the density field from the eddy rich model has high temporal variability along 34 s with spatial scale of about two hundred km that can be due to mesoscale variations caused by agulhas leakage this results in the decrease of the mean meridional geostrophic velocity which leads to smaller values of the amoc and mht in glob16 subsampling glob16 density on or longitude grid along 34 s for mocob calculation significantly increases the amoc values the findings in this paper provide guidance in understanding amoc and mht dissimilarities between observation based estimates and eddy rich ocean models at 34 s

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

attenuation of rare earth elements in a boreal estuary this study focuses on attenuation of rare earth elements ree when a boreal creek acidified and loaded with ree and other metals as a result of wetland drainage empties into a brackish water est

hydrogeochemistry and rare earth element behavior in a volcanically acidified watershed in patagonia argentina abstract the rio agrio watershed in northern patagonia argentina is naturally acidic due to discharges of volcanic h 2 so 4 hcl and hf at its headwaters near the summit of copahue volcano a suite of water samples was collected from the summit of the volcano to a point roughly 40 km downstream where the ph of the rio agrio rose above 6 0 this suite included a sample of the hyperacidic ph the concentrations of ree in the rio agrio decreased by several orders of magnitude through the study area as a result of dilution and chemical attenuation a subtle shift in the slope of shale normalized profiles of dissolved ree concentration was observed from being weakly positive near the source of the rio agrio to showing a weak middle ree enrichment trend in lake caviahue to being weakly negative in the lower reaches of the river the trend to a negative slope across the lanthanide series in the lower river is explained by selective partitioning of the heavier ree to hydrous oxides of fe and al suspended in the water column and accumulating on the riverbed most of the decrease in ree load occurred immediately downstream of the confluence with a tributary that increased the ph of the rio agrio from 4 3 to 6 1 although the mixed water was supersaturated with ree phosphate compounds precipitation of lnpo 4 is not believed to have been a dominant process because the predicted pattern of inter element fractionation from phosphate deposition is inconsistent with the observed trends instead ree attenuation most likely occurred from adsorption onto freshly precipitated hydrous aluminum oxide the behavior of ree in the rio agrio watershed is broadly similar to what has been observed in watersheds that owe their acidity to oxidation of sulfide minerals

studies of labrador sea water formation and variability in the subpolar north atlantic in the light of international partnership and collaboration abstract labrador sea water lsw the lightest contribution to north atlantic deep water nadw and one of the most prominent water masses of the subpolar north atlantic has seen remarkable changes over the past century lsw originates in the labrador sea where it is formed through wintertime ocean convection of varying intensity depth and spatial extent formation of lsw followed by its respective injection into the mid depth circulation system is mandatory for ventilating and renewing water layers of the interior ocean indispensably important for unraveling the history of variability in formation and properties of lsw as well as for mapping its large scale spreading and export are sustained physical and chemical observations from the deep ocean these observations started at the beginning of the 20th century from occasional mostly national surveys and today constitute large scale multi national collaborative efforts including a vast arsenal of sophisticated instrumentation in a historical context we revisit major milestones over the past 100 years which have established and are constantly adding to shaping today s knowledge on lsw and present first details on the latest vintage of lsw generated during the strong winter of 2013 2014 respective argo data reveal mixed layer depths greater than 1700 m marking formation of a new cold and fresh anomaly that has spread since then over the subpolar north atlantic we further summarize the on going observational efforts in the subpolar north atlantic and present a compilation of hydrographic standard lines that serve to provide top to bottom information on nadw components

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

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

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

the rare earth element geochemistry of acid sulphate and acid sulphate chloride geothermal systems from yellowstone national park wyoming usa rare earth element ree concentrations have been determined by inductively coupled plasma mass spectrometry icp ms in acid sulphate and acid sulphate chloride waters and the associated sinters and volcanic rocks from the yellowstone national park ynp wyoming usa geothermal system ree concentrations in the volcanic rocks range from 222 to 347 ppm their chondite normalised ree patterns are typical of upper continental crust with lree hree and negative eu anomalies total ree concentrations in the fluids range from 3 to 1133 nmol kg 1 162 ppm and ree concentrations in sinter are 181 ppm ree abundances and patterns in drill core material from ynp indicate some ree mobility normalisation of ree concentrations in altered lava creek tuff lct from y 12 drill core to ree concentrations in fresh lct indicate that the ree overall have been depleted with the exception of eu which has been decoupled from the ree series and concentrated in the altered rocks relative to the host rocks the ree patterns of the fluids are variably depleted in hrees and lrees and usually have a pronounced positive eu anomaly this decoupling of eu from the ree suite suggests that 1 eu has been preferentially removed either from the host rock glass or from the host rock minerals or 2 the waters are from a high temperature or reducing environment where eu2 is more soluble than the trivalent rees since the latter is inconsistent with production of acid sulphate springs in a low temperature oxidising near surface environment we suggest that the positive eu anomalies in the fluids result from preferential dissolution of a eu rich phase in the host rock spatial and temporal variations in major element chemistry and ph of the springs sampled from norris geyser basin and crater hills accompany variations in ree concentrations and patterns of individual geothermal springs these are possibly related to changes in subsurface plumbing which results in variations in mixing and dilution of the geothermal fluids and may have lead to changes in the extent and nature of ree complexing

rare earth element mineralogy and geochemistry in a laterite profile from madagascar abstract in this study rare earth element ree distribution has been investigated in a weathering profile from central madagascar combination of bulk rock geochemical data elements and isotopes with mineral characterization reveals a remarkable evolution of the ree abundances and ree minerals in the vertical weathering profile in the fresh tonalite bedrock ree y concentrations are typical of granitoids 299 363 ppm and the main ree minerals are allanite and chevkinite in the c horizon saprolite primary ree minerals disappear and rees are transported via fluid to precipitate rhabdophane group minerals in cracks and pores the presence of sulfate ligands produced by sulfide oxidation may be responsible for the ree speciation as suggested by the composition of the secondary ree minerals rhabdophane group minerals contain up to 9 wt so 3 and 7 wt cao indicating a mixture between rhabdophane sensu stricto ree po 4 h 2 o and tristamite ca u fe iii po 4 so 4 2h 2 o due to intense ca leaching rhabdophane disappears and al phosphates alunite jarosite group are found in the soil cerianite ce iv o 2 also precipitates in the b horizon of the soil mass transfer calculations based on immobile ti indicate significant ree leaching in a horizon with preferential leaching of the heavy ree rees accumulate partly in the b horizon the uniform nd isotope compositions and the constant proportion of immobile elements do not reveal external input in the b horizon total ree y reach 2194 ppm with high ce concentrations 1638 ppm 9 ce bedrock compared to other ree 3 4 ree bedrock tetravalent ce state is dominant in the b horizon and requires oxidizing conditions that likely account for the accumulation of redox sensitive elements in b horizon e g mn fe co under oxidizing conditions cerianite precipitation causes a ce fractionation from other trivalent ree in comparison to the ion adsorption clay of southern china preferential heavy ree enrichment was not observed in the weathering profile another remarkable peculiarity of the studied profile is the occurrence of gd 2 so 6 grains the discovery of this new mineral demonstrates that a natural process exists that that can fractionate ree to such an extent to produce a pure gadolinium end member mineral an understanding of such a mechanisms is crucial for the ree geochemistry of low temperature alteration processes as well as for the formation of ree ore deposits or industrial processing

multiple implications of rare earth elements for holocene environmental changes in nam co tibet abstract rare earth elements rees from a 332 cm long core surface sediments and soils of the lake shores were examined with the aim of evaluating their suitability as a paleo environmental proxy rees were transported into the nam co lake not only by runoff but also by wind concentrations of ree in the core range from 97 57 to 162 98 ppm with an average of 126 5 ppm from 171 3 to 475 7 ppm in the soils of shores and from 65 03 to 354 03 ppm in the surface sediments with an average of 130 64 ppm the ree average of soils is 158 9 ppm for the northern shore 214 72 ppm for the southern shore 244 ppm for the eastern shore and 289 69 ppm for the western shore the ree average of surface sediments is 114 45 ppm for the northern lake 115 73 ppm for the eastern lake 129 69 ppm for the western lake 144 38 ppm for the southern lake and 150 95 ppm in the center of the lake suggesting an accumulation of rees in the center of the lake the ratios of lree hree range from 8 to 11 85 for the core from 7 8 to 11 8 for the surface sediments and from 6 5 to 14 5 for the soils which suggesting that lree are richer than hree the ree distribution patterns of all samples are characterized by v shape curves with slightly negative ce anomalies from 0 83 to 0 99 and obviously negative eu anomalies from 0 28 to 0 72 mn played an active role on the ce anomaly the values of ce showed almost no variance suggesting a stable post depositional environment in the core the rees peaks of 140 ppm occurred at 6 9 ka 307 cm 5 9 5 5 ka 292 287 cm 2 2 2 0 ka 262 252 cm and 1 78 ka 212 cm corresponding to the beginning of environmental shifts and or events while the rees peak at 0 91 0 87 ka 107 102 cm and the rees valley of

genesis of ree minerals in the karstic bauxite in western guangxi china and its constraints on the deposit formation conditions abstract karstic bauxites in western guangxi china comprise two subtypes permian bauxite and quaternary bauxite the quaternary bauxite originated from the breaking up rolling and accumulating of permian bauxite in karstic depressions in quaternary various types of rare earth element ree minerals were discovered during the formation of the permian and quaternary bauxites from the xinxu longhe and tianyang bauxite deposits in this study five types of ree minerals including bastnasite parisite cerianite rhabdophane and churchite were identified bastnasite and parisite are the most abundant and they are widely developed in the permian ore and also present in the quaternary ore obvious variations in bastnasite and parisite ree compositions were observed which is ascribed to distinctions in the source materials in the primary weathering profile from different areas the mode of occurrence of bastnasite and parisite suggests they were mainly precipitated under alkaline and reducing conditions during the permian bauxite forming stage and underwent intensive corrosion in the quaternary churchite was formed during the permian weathering stage under acidic condition both cerianite and rhabdophane occur in fractures within the permian bauxite ore indicating that both formed during the quaternary weathering stage it is considered that the rhabdophane enriched in ce have formed locally in the process of that the ce3 released from bastnasite rapidly entered the rhabdophane lattice before being oxidized to ce4 cerianite was mainly found in association with mn al hydroxides suggesting that the released ce3 was oxidized into ce4 and precipitated cerianite in fractures within the permian bauxite ore mass balance equations reveal a depletion in nearly all rees during the transformation from the permian to the quaternary bauxite ore mainly caused by the dissolution of bastnasite and parisite the genesis of the ree minerals together with the occurrence of other minerals indicates that intensively acidic and oxidizing conditions developed before the formation of the permian bauxite ore towards the end of the permian the conditions became reducing and alkaline favorable for the large scale bauxitization the quaternary bauxite forming stage was characterized by variable ph and eh conditions with acidic ph 4 6 and oxidizing eh 2 conditions at the surface of the exposed permian bauxite ore

basinwide response of the atlantic meridional overturning circulation to interannual wind forcing an eddy resolving ocean general circulation model for the earth simulator ofes and a simple wind driven two layer model are used to investigate the role of momentum fluxes in driving the atlantic meridional overturning circulation amoc variability throughout the atlantic basin from 1950 to 2010 diagnostic analysis using the ofes results suggests that interior baroclinic rossby waves and coastal topographic waves play essential roles in modulating the amoc interannual variability the proposed mechanisms are verified in the context of a simple two layer model with realistic topography and only forced by surface wind the topographic waves communicate high latitude anomalies into lower latitudes and account for about 50 of the amoc interannual variability in the subtropics in addition the large scale rossby waves excited by wind forcing together with topographic waves set up coherent amoc interannual variability patterns across the tropics and subtropics the comparisons between the simple model and ofes results suggest that a large fraction of the amoc interannual variability in the atlantic basin can be explained by wind driven dynamics

jarosites and their application in hydrometallurgy the alunite supergroup consists of more than 40 minerals with the general formula dg 3 t o4 2 oh h2o 6 wherein d represents cations with a coordination number greater or equal to 9 and g and t represent sites with octahedral and tetrahedral coordination respectively smith et al 1998 the supergroup is commonly subdivided into various groups but the simplest primary subdivision is on the basis of the g cations for all of the minerals in the supergroup the dominant g cation is trivalent most of the minerals have g represented by fe3 or al3 but exceptions are the rare minerals gallobeudantite in which g is ga3 and springcreekite in which g is v3 table 1 thus the primary grouping adopted here is on whether formula fe3 exceeds or is subordinate to al3 the hierarchical sequence in mineralogy seems to be variable but here the decreasing sequence is given as supergroup family group and subgroup minerals with fe3 al3 are referred to as belonging to the jarosite family and those with a13 fe3 are allocated to the alunite family view this table table 1 minerals of the alunite supergroup subdivision of the alunite and jarosite families has also been variable scott 1987 for example used seven groups novak et al 1994 used six gaines et al 1997 used four and mandarino 1999 used three the arbitrary decision here is to use three groups which differ from those of mandarino 1999 but which in general indicate whether sulfate phosphate or arsenate predominates in the t o4 tetrahedra the three groups are the alunite group in which t o4 is dominated by so4 the crandallite group in which po4 is

geochemistry of the rare earth elements and uranium in the acidic berkeley pit lake butte montana abstract filtered 0 45 m and nonfiltered concentrations of rare earth elements ree u zr th ba sc and y were measured as a function of depth in the berkeley pit lake a large acidic mining lake in butte mt the ree show very little variation with depth apart from a slight concentration near the surface presumably due to evaporation the ree profiles of the pit waters show a depletion in light ree when normalized against nasc and the host butte quartz monzonite bqm and a possible enrichment in middle ree vs heavy ree when normalized against bqm all of the ree partitioned weakly into secondary ferric precipitates formed by aging of deep berkeley pit water the measured distribution coefficients increased across the lanthanide series from la kd 7 7 to nd kd 10 3 and then decreased steadily to lu kd 1 4 under the conditions of the berkeley pit lake the aqueous speciation of ree and u is dominated by sulfate complexes because the stability constants of ree sulfate complexes show very little variation across the lanthanide series the observed trends in kd cannot be explained by aqueous complexation despite high concentrations of dissolved ree e g 1 1 mg l ce and u 0 85 mg l saturation indices for all solid phases were strongly negative due to the low ph of the berkeley pit lake 2 3 2 6 the mobility of ree and u is more likely constrained by adsorption or co precipitation with strengite jarosite schwertmannite or other secondary minerals forming in the lake

seasonal variations in the south atlantic meridional overturning circulation from observations and numerical models monthly climatologies of temperature and salinity from observations and numerical models are used to estimate the atlantic meridional overturning circulation amoc at 34 s observational estimates suggest that the geostrophic transport plays an equal role to the ekman transport in the amoc seasonal variations at this latitude whereas in the models the ekman transport controls the amoc seasonality the seasonality of the geostrophic transport from observations is largely controlled by the seasonal density variations at the western boundary but in the models the eastern boundary dominates the observed density seasonality at the western boundary is linked to the intensity of the malvinas current which is poorly reproduced in the models the results indicate that the weak seasonal cycle in the model geostrophic transport can primarily be attributed to excessively strong baroclinicity below the surface mixed layer whereas the observations show a strong vertical coherence in the velocity down to 1200 m

oceanic fluxes on the woce a11 section abstract the most southerly woce one time section in the south atlantic designated a11 was occupied in january 1993 the cruise track lay across the cool subantarctic zone of the circumpolar current in the west and the warm subtropical gyre in the east in this paper estimates of the flux of heat salt oxygen and other tracers across the section are presented a brief description of the distribution of physical and chemical properties is followed by a determination of the flux in the surface ekman layer direct measurements of current shear made from a shipborne adcp and estimates from cruise wind data and climatological data all yield a flux of 5 1 sv sv 106 m3 s 1 equatorward when combined with geostrophic estimates relative to a level near 3500 dbar or the bottom where shallower an initial guess for the flow field is derived this initial guess is combined with absolute currents derived from the adcp when the ship is underway unrealistic aspects of the circulation are found and we conclu

adsorption of rees on kaolinite and halloysite a link to the ree distribution on clays in the weathering crust of granite abstract the clay minerals kaolinite and halloysite are dominant hosts for rare earth elements rees in the weathered crust elution deposited ree deposits however the accumulation of rees on kaolinite and halloysite has not been systematically compared in this study the adsorption of complete ree series on kaolinite and halloysite was investigated under different ph levels and ionic strengths which was linked to the enrichment and fractionation of rees within the clay fraction of a typical weathered crust elution deposited ree deposit at low ionic strength the adsorption of rees on kaolinite and halloysite increased with increase in ph with some noticeable fluctuation observed on halloysite at high ph all the rees were adsorbed to a similar extent without apparent fractionation except for the slight enrichment of heavy rees hrees at high ph at high ionic strength ree adsorption exhibited a linear increase with the increase in ph particularly at high ph with hrees being preferentially adsorbed compared to halloysite kaolinite possessed a higher specific surface area ssa normalized adsorption capacity towards rees these observed adsorption characteristics could possibly explain the distribution of rees in the clay fraction along the ree deposit the decrease of ion exchangeable ree content with depth was significant for kaolinite while the ree fractionation was ascribed to the selective adsorption of hrees on both kaolinite and halloysite the enrichment and fractionation mechanism of rees on kaolinite and halloysite were also discussed in terms of the surface chemistry and morphology of the clay minerals and the variations of chemical properties across the ree group

atmospheric origins of variability in the south atlantic meridional overturning circulation abstractinsights from the rapid mocha observation network in the north atlantic have motivated a recent focus on the south atlantic where water masses are exchanged with neighboring ocean basins

meridional overturning circulation transport variability at 34 5 s during 2009 2017 baroclinic and barotropic flows and the dueling influence of the boundaries

phytoplankton biomass cycles in the north atlantic subpolar gyre a similar mechanism for two different blooms in the labrador sea an analysis of seasonal variations in climatological surface chlorophyll points to distinct biogeographical zones in the north atlantic subpolar gyre in particular the labrador sea appears well delineated into two regions on either side of the 60 n parallel with very different climatological phytoplankton biomass cycles indeed north of 60 n an early and short spring bloom occurs in late april while south of 60 n the bloom gradually develops 1 month later and significant biomass persists all summer long nevertheless at climatological scale the first order mechanism that controls the bloom is identical for both bioregions the light mixing regime can explain the bloom onset in both bioregions in the labrador sea the blooms seem to rely on a mean community compensation irradiance threshold value of 2 5 mol photon m 2 d 1 over the mixed layer

on multidecadal variability of the atlantic meridional overturning circulation in the community climate system model version 3 abstract multidecadal variability of the atlantic meridional overturning circulation moc is investigated diagnostically in the ncar community climate system model version 3 ccsm3 present day simulations using the highest t85 1 resolution version this variability has a 21 yr period and is present in many other ocean fields in the north atlantic in moc the oscillation amplitude is about 4 5 sv 1 sv 106 m3 s 1 corresponding to 20 of the mean maximum moc transport the northward heat transport nht variability has an amplitude of about 0 12 pw representing 10 of the mean maximum nht in sea surface temperature sst and sea surface salinity sss the peak to peak changes can be as large as 6 7 c and 3 psu respectively the labrador sea region is identified as the deep water formation dwf site associated with the moc oscillations in contrast with some previous studies temperature and salinity contributions to the total density in this dwf region are almost equal and in phase the he

assessing the impact of serwis mine tailings site on farmers wells using element and isotope signatures holy cross mountains south central poland this paper presents the results of a geochemical and isotopic study of technogenic soils and acid pool waters in the abandoned mine tailings pile and its potential impact on the adjacent farmers wells at the village of serwis south central poland the acid tailings pools showed strong trace element and ree signals these acid pools were featured by the predominance of medium rare earth elements mree with a strong positive gd anomaly the technogenic soils also revealed a mree roof shaped pattern but with distinct positive excursions in gd sm eu and ce the 34s so42 signatures of acid pool waters mean of 1 3 were close to those of soils and pyrite means of 2 3 and 3 2 respectively the waters of four farmers wells exhibited nearly the same 34s so42 values 0 7 4 0 as the nearby acid pool waters 0 3 3 1 the similar 34s isotope signatures combined with the highest contents of dissolved so42 181 577 mg l in these wells suggest that the tailings pile is a potential source of so42 derived from pyrite weathering this relationship may also be evidenced by a spatial site variable dendrogram that groups these four wells into one cluster at the linkage distance dlink dmax 100 53

bio optical observations of the 2004 labrador sea phytoplankton bloom 1 a unique time series of moored bio optical measurements documented the 2004 spring summer bloom in the southern labrador sea in situ and satellite chlorophyll data show that chlorophyll levels in the 2004 bloom were at the upper end of those typically observed in this region satellite chlorophyll and profiling float temperature salinity data show that the main bloom which typically peaks in june july is often preceded by ephemeral mixed layer shoaling and a lesser short lived bloom in may this was the case in 2004 the particulate backscatter to beam attenuation ratio bbp 470 nm cp 660 nm showed peaks in the relative abundance of small particles at bloom initiation and during the decline of the bloom while larger particles dominated during the bloom chlorophyll cp and bbp chlorophyll were correlated with carbon export and dominated by changes in the pigment per cell associated with lower light levels due to enhanced attenuation of solar radiation during the bloom an npz nutrients phytoplankton zooplankton model captured the phytoplankton bloom and an early july peak in zooplankton moored acoustic doppler current profiler adcp data showed an additional mid june peak in zooplankton biomass which was attributed to egg laying copepods the data reported here represent one of the few moored time series of cp bbp and chlorophyll extending over several months in an open ocean region interpretation of data sets such as this will become increasingly important as these deployments become more commonplace via ocean observing systems moreover these data contribute to the understanding of biological physical coupling in a biogeochemically important yet poorly studied region

rapid development of negative ce anomalies in surface waters and contrasting ree patterns in groundwaters associated with zn pb massive sulphide deposits ground and surface waters collected from two undisturbed zn pb massive sulphide deposits the halfmile lake and restigouche deposits and active mines in the bathurst mining camp bmc nb canada were analysed for the rare earth elements ree ree contents are highly variable in waters of the bmc with higher contents typical of waters with higher fe and lower ph there are significant differences between ground and surface waters and between groundwaters from different deposits the ree contents of surface waters are broadly similar within and between deposit areas although there are spatial variations reflecting differences in ph and redox conditions surface waters are characterised by strong negative ce anomalies ce ce nasc as low as 0 08 produced by oxidation of ce3 to ce4 and preferential removal of ce4 from solution upon leaving the shallow groundwater environment groundwaters and seeps typically lack significant ce anomalies reflecting generally more reducing conditions in the subsurface environment and indicating that ce oxidation is a rapid process in the surface waters deeper groundwaters at the halfmile lake deposit are characterised by ree patterns that are similar to the host lithologies whereas most groundwaters at the restigouche deposit have lree depleted patterns compared to nasc halfmile lake deposit groundwaters have generally lower ph values whereas restigouche deposit groundwaters show greater heavy ree complexation by carbonate ions shallow waters at the halfmile lake and stratmat main zone deposits have unusual patterns which reflect either the adsorption of light ree onto colloids and fracture zone minerals and or precipitation of ree phosphate minerals middle ree enrichment is typical for ground and surface waters and is highest for neutral ph waters the labile portion of stream sediments are generally more middle ree enriched than total sediment and surface waters indicating that the ree are removed from solution by adsorption to fe and mn oxyhydroxides in the order middle ree light ree heavy ree

water rock interaction in an acidic mine discharge as indicated by rare earth element patterns abstract the rare earth element ree composition of an acidic spring discharging at ph 2 7 was studied in relation to the ree composition of selected extracts of the coal bearing strata hydrologically above the discharge the low ph of the discharge and the access to the strata through which it flows provides an excellent opportunity to study the use of rees as tracers of water rock interaction extraction techniques were used to mimic the process of acidic groundwater generation in coal bearing strata samples were treated to remove exchangeable ions and then treated sequentially with solutions buffered at ph 5 5 3 6 and 1 6 in order to mimic the natural buffering systems of groundwaters finally samples were oxidised with hydrogen peroxide in an attempt to remove the pyrite the results show that the composition of the spring is controlled by pyrite oxidation and buffering by fe oxy hydroxides the latter with compositions inherited from carbonates from within the sequence the similarity of ree patterns of the carbonate and the silicate extracts tends to obscure information concerning the relative roles of carbonate or silicate phases the source strata of the spring has evolved over time and shows that different coal seams have a unique contribution this distinct contribution appears more related to the mixture of sedimentary components i e carbonates silicates etc in the coal seam and the combination of shale and sandstone layers surrounding coal seams than the composition of the components themselves the similarity between ree compositions of the sequential extracts suggests that relationships discovered for this spring will be applicable elsewhere in the basin however this very property will hamper the use of such lithophilic elements in cases where characterisation of the source area is not possible

rare earth elements in pore waters of marine sediments abstract the rare earth elements rees were measured in pore waters of the upper 25 cm of sediment from one site off peru and three sites on the california margin the pore water ree concentrations are higher than sea water and show systematic down core variations in both concentration and normalized pattern from these analyses and from comparison to other chemical species measured dissolved fe mn ba oxygen nitrate phosphate it is suggested that pore water rees can be grouped into three categories those that are from an fe source those that are from a poc source and cerium oxide rees from the fe source appear where anoxia is reached they have a distinctive middle ree mree enriched pattern the concentrations in this source are so elevated that they dominate ree trends in the fe oxide reduction zone the net result of flux from the poc source is relative enrichment of heavy rees hrees over light rees lrees reflecting remineralizing poc and complexation with doc a common linear ree pattern seen in both oxic and anoxic sediments is associated with this poc source as well as a hree enriched pattern that is seen in surficial sediments at the peru site overall the pore water results indicate that mn oxides are not an important carrier of rees in the oceans a ree biogeochemical model is presented which attempts to reconcile ree behavior in the water and sediment columns of the oceans the model proposes that poc fe oxide and ce oxide sources can explain the ree concentration profiles and relative abundance patterns in environments ranging from oxic sea water to anoxic pore water the model is also consistent with our observation that the ce anomaly of pore water does not exceed unity under any redox condition

rare earth elements as a tool for studying the formation of cemented layers in an area affected by acid mine drainage abstract in a profile with two cemented layers sampled in an area affected by acid mine drainage both have rare earth element ree signatures with positive ce anomalies in the post archean australian shale normalised patterns both cemented layers have higher contents of environmentally relevant metals cd co cu fe mn u and zn than the over and underlying unconsolidated quaternary sediments and are depleted of al ca k and mg the cemented layers are enriched in middle and heavy ree but only the bulk pattern of the lower cemented layer reveals a positive ce anomaly for the upper cemented layer this positive ce anomaly was only determined by spatially resolved laser ablation inductively coupled plasma mass spectrometry la icp ms studies only for segments with a high abundance of mn occurring as mn phases as proven by energy dispersive x ray spectroscopy the mn phases are formed secondarily to the ferric cement and are especially enriched in ce and co the ce anomaly of the lower cemented layer most probably is inherited from groundwater to the ferric cement whereas the ce anomaly of the upper cemented layer is the result of preferential scavenging of ce onto the mn phases compared to other ree

rapid freshening of the deep north atlantic ocean over the past four decades the overflow and descent of cold dense water from the sills of the denmark strait and the faroe shetland channel into the north atlantic ocean is the principal means of ventilating the deep oceans and is therefore a key element of the global thermohaline circulation most computer simulations of the ocean system in a climate with increasing atmospheric greenhouse gas concentrations predict a weakening thermohaline circulation in the north atlantic as the subpolar seas become fresher and warmer1 2 3 and it is assumed that this signal will be transferred to the deep ocean by the two overflows from observations it has not been possible to detect whether the ocean s overturning circulation is changing but recent evidence suggests that the transport over the sills may be slackening4 here we show through the analysis of long hydrographic records that the system of overflow and entrainment that ventilates the deep atlantic has steadily changed over the past four decades we find that these changes have already led to sustained and widespread freshening of the deep ocean

cycling of trace metals and rare earth elements ree in acid sulfate soils in the plain of reeds vietnam abstract trace metals and rare earth elements ree are subject to intensive chemical cycling in acid sulfate soils the oxidation of pyrite bearing deposits and the subsequent acidification mobilizes a variety of trace metals and ree in this study solid phase and pore water data of three cores from the plain of reeds in the mekong river delta vietnam were analyzed distinct authigenic enrichments of trace metals and ree were observed in the solid phase of these cores thermodynamic modeling was employed to elucidate the controls on trace metal and ree mobility and the governing factors for the formation of these authigenic enrichments the formation of ree enrichments in these settings is clearly controlled by ph and the availability of potent sorbents under suitable conditions trace metals such as e g zinc nickel and cobalt are likely bound as trace metal monosulfides in the enrichment zones the solid phase and pore water data and the results of a thermodynamic model suggest a possible sequential precipitation of trace metal sulfides however the incorporation of trace metals into iron sulfides cannot be ruled out in the case of lead and arsenic the formation of pb as jarosite proved to be a further major sink these insights provide a better understanding of the controls and governing factors for trace metal and ree mobility in acid sulfate soils and will therefore help to assess impacts on soil and water

microbial controls on phosphate and lanthanide distributions during granite weathering and soil formation abstract both microbial and geochemical factors control the form distribution and abundance of lanthanides during weathering and soil formation in a profile in the bemboka granodiorite from southern new south wales australia during the initial stages of weathering hydrous ce bearing lanthanide and lanthanide aluminum phosphates including rhabdophane and florencite crystallize on etched apatite surfaces throughout the profile however their fate depends greatly on their location within the profile in rocks weathered 5 6 m below the soil zone the lower profile secondary lanthanide phosphates persist long after all apatite has been dissolved however in rocks weathered within 2 m of the soil zone the upper profile secondary phosphates are dissolved and lanthanides other than ce are removed bacteria and fungal hyphae are localized on secondary phosphate surfaces suggesting that rhabdophane and florencite are solubilized in the upper profile due to organic complexation of dissolved lanthanides and or uptake of phosphate by cells in the soils defined by loss of granitic texture secondary phosphates are replaced by ce oxides lanthanides other than ce removed in solution from the upper profile precipitate as ce poor phosphates in the lower profile when the solubility product is exceeded due to high dissolved phosphate concentrations in proximity to apatite thus the upper profile is the source of lanthanides added to the lower profile in both the lower and upper weathered granite the degree to which weight based ce abundances increase with increasing weathering is consistent with ce immobility on the centimeter scale we attribute the very high weight based ce abundances up to 12 concentrations in fresh rock to extensive leaching and compaction during transformation of weathered rock to soil

δ18o and ree contents of phosphatic brachiopods a comparison between modern and lower paleozoic populations 18o values of both carbonate 18 7 25 1 and phosphate 15 1 16 7 components of the francolite from the fossil brachiopod shells are interpreted as the result of a partial resetting of pristine isotopic compositions the similarity of hat shape ree patterns of some lower ordovician linguloids with those of extant littoral specimens suggests the preservation of a 500 myr old record of ree marine chemistry in agreement with the known paleogeography the phosphatic brachiopods have been deposited in a coastal environment under shallow and oxygenated marine waters however the contents and distribution of ree in some strongly altered brachiopod shells reveal an alteration of the original negative ce anomalies and both nd and sm enrichments that transformed the initial hat shape patterns of linguloids into strongly convex or bell shape patterns

transfer function between surface sediment diatom assemblages and sea surface temperature and salinity of the labrador sea abstract q mode factor analysis cabfac of 38 diatom species in 66 surface sediment samples from the labrador sea allowed the definition of six assemblages explaining 95 69 of the total variance the first assemblage 40 12 of the total variance is represented by thalassiothrix longissima a species characteristic of the irminger current and associated with the west greenland current the second assemblage 34 52 of the total variance is represented by thalassiosira gravida resting spores a cold water species associated with the labrador current a third assemblage 11 43 of the variance represented by chaetoceros spp is concentrated in the northeastern section of the labrador sea and associated with upwelling and high productivity the fourth the fifth and the sixth assemblages represented respectively by coscinodiscus marginatus coscinodiscus oculus iridis and coscinodiscus divisus and nitzschia frigida are less significant and account respectively for 4 95 2 62 and 2 04 of the total variance transfer functions derived by relating factor assemblages to surface water temperature and salinity august and february give standard errors of estimate of 0 93 c august and 0 64 c february for temperature and of 0 58 august and 0 45 february for salinity high correlations between the measured and estimated parameters confirm the validity of the paleoecological equations for the reconstruction of the labrador sea paleoclimate

a new collective view of oceanography of the arctic and north atlantic basins abstract we review some historical aspects of the major observational programs in the north atlantic and adjacent regions that contributed to establishing and maintaining the global ocean climate monitoring network the paper also presents the oceanic perspectives of climate change and touches the important issues of ocean climate variability on time scales from years to decades some elements of the improved understanding of the causes and mechanisms of variability in the subpolar north atlantic and adjacent seas are discussed in detail the sophistication of current oceanographic analysis especially in connection with the most recent technological breakthroughs notably the launch of the global array of profiling argo floats allows us to approach new challenges in ocean research we demonstrate how the ocean climate changes in the subpolar basins and polar seas correlate with variations in the major climate indices such as the north atlantic oscillation and atlantic multidecadal oscillation and discuss possible connections between the unprecedented changes in the arctic and greenland ice melt rates observed over the past decade and variability of hydrographic conditions in the labrador sea furthermore a synthesis of shipboard and argo measurements in the labrador sea reveals the effects of the regional climate trends such as freshening of the upper layer possible causes of which are also discussed on the winter convection in the labrador sea including its strength duration and spatial extent these changes could have a profound impact on the regional and planetary climates a section with the highlights of all papers comprising the special issue concludes the preface

oxygenation of acid sulfate soils stimulates co2 emission roles of acidic dissolution and hydroxyl radical oxidation abstract emission of co2 from acid sulfate soil regions has received great attention in recent years production of co2 due to microbial respiration has been documented by previous studies but the abiotic mechanisms are poorly understood in this study co2 production was measured from oxygenation of 60 acid sulfate soil samples that were collected from a typical acid sulfate soil region the soil samples were characterized by low ph 3 3 5 8 and high sulfate content 0 51 5 03 mg g the cumulative concentrations of co2 were 0 76 54 54 mol per g dry soil upon oxygenation for 24 h when 0 1 hgcl2 was added into soil suspension to kill microbes the yield of co2 decreased by 8 7 41 1 which suggests that both microbial respiration and abiotic pathways contributed to co2 production and abiotic pathway played a major role both acidic dissolution and hydroxyl radical oh oxidation were identified to be the abiotic mechanisms for co2 production for acidic dissolution co2 was produced from the decomposition of carbonate by h generated production of co2 from acidic dissolution was dependent on the content of carbonate and the generation of h a combination of fe speciation sequential extraction and kinetic model shows that h was mainly generated from the oxidation of both fe2 and pyrite by o2 for oh oxidation co2 was produced from the oxidation of organic carbon by oh produced and its relative importance for co2 production was estimated to be 14 6 27 6 oh was mainly produced from exchangeable fe ii oxidation in sulfuric horizon but from pyrite oxidation in potential acid sulfate soils this study presents the overlooked abiotic mechanisms acidic dissolution and oh oxidation for co2 emission in acid sulfate soils when perturbed by o2 our findings implicate that contribution of microbial respiration for co2 production is not as large as previously thought to be in acid sulfate soils and instead abiotic mechanisms contribute largely particularly for oxygenation of potential acid sulfate soils

environmental geochemistry of rare earth elements in cu porphyry mine tailings in the semiarid climate conditions of sarcheshmeh mine in southeastern iran abstract sarcheshmeh mine is one of the largest oligo miocene porphyry cu deposits in the world it is located in the kerman cenozoic magmatic arc in southeastern iran this paper discusses the geo environmental behavior of rare earth elements rees in the sarcheshmeh dammed tailing pond situated in semiarid climate for this purpose solid and water samples were collected to consider 1 weathering oxidation reactions and upward migration of soluble elements 2 super saturation and formation dissolution of the secondary evaporative phases 3 hydro geochemical changes of the surface and groundwater resources 4 flotation of the cu sulfide ore and tailing management strategies the mean values of the rees for fresh and weathered tailings and the evaporative phases were 113 0 103 7 and 74 6 mg kg respectively when compared with the fresh and weathered tailings the evaporative phases showed significant enrichment of hrees and a well depleted pattern of lrees except for that of eu this geochemical pattern suggests a higher solubility and mobility potential of hrees and eu compared with lrees resulting in good fractionation and enrichment of these elements in the surface evaporative layer formed on top of the weathered tailings the water samples showed a range of hydro geochemical features under acidic ph of 2 5 to 4 7 near neutral ph of 6 4 to 7 9 alkaline ph of 8 to 10 and highly alkaline ph 10 conditions the maximum concentration of rees was observed in the acidic waters produced by the weathered tailings after rainfall rees of 489 to 1903 g l although rees decreased as the ph value increased the general trend was compatible with the highest concentration of hrees rather than lrees the speciation calculations indicate that lnso4 ln so4 2 and ln3 are the primary forms of dissolved rees at acidic and near neutral ph and the dominant species was lnso4 lnco3 40 78 ln co3 2 31 68 and lnso4 31 07 were the dominant species under alkaline conditions at high alkaline ph the speciation pattern changed to lnoh2 53 15 ln co3 2 44 88 and lnco3 2 61 where ln denotes lanthanide based on the results and considering previous works it appears that ionic potential plays an important role in the geo environmental behavior of rees of adsorption tendency mobility potential and ionic substitution

sulfur biogeochemical cycling and novel fe s mineralization pathways in a tidally re flooded wetland abstract sulfur biogeochemical cycling and associated fe s mineralization processes exert a major influence over acidity dynamics electron flow and contaminant mobility in wetlands benthic sediments and groundwater systems while s biogeochemical cycling has been studied intensively in many environmental settings relatively little direct information exists on s cycling in formerly drained wetlands that have been remediated via tidal re flooding this study focuses on a tidal wetland that was drained in the 1970s causing severe soil and water acidification and subsequently remediated by controlled re flooding in 2002 we examine so 4 2 reduction rates and fe s mineralization at the tidal fringe 7 years after the commencement of re flooding the initial drainage of the wetland examined here caused in situ pyrite fes2 oxidation resulting in the drained soil layers being highly acidic and rich in so 4 2 bearing fe iii minerals including jarosite kfe3 so4 2 oh 6 tidal re flooding has neutralized much of the previous acidity with the pore water ph now mostly spanning ph 5 7 the fastest rates of in situ so 4 2 reduction up to 300 nmol cm 3 day 1 occur within the inter tidal zone in the near surface soil layers to 60 cm below ground surface the so 4 2 reduction rates correlate with pore water dissolved organic c concentrations thereby suggesting that electron donor supply was the predominant rate determining factor elemental s was a major short term product of so 4 2 reduction comprising up to 69 of reduced inorganic s in the near surface soil layers this enrichment in elemental s can be partly attributed to interactions between biogenic h2s and jarosite a process that also contributed to enrichment in pore water fe2 up to 55 mm and so 4 2 up to 50 mm the iron sulfide thiospinel greigite fe3s4 was abundant in near surface soil layers within the inter to sub tidal zone where tidal water level fluctuations created oscillatory redox conditions there was evidence for relatively rapid pyrite re formation within the re flooded soil layers however the results indicate that pyrite re formation has occurred mainly in the lower formerly drained soil layers whereas the accumulation of elemental s and greigite has been confined towards the soil surface the discovery that pyrite formation was spatially decoupled from that of elemental s and greigite challenges the concept that greigite is an essential precursor required for sedimentary pyrite formation in fact the results suggest that greigite and pyrite may represent distinct end points of divergent fe s mineralization pathways overall this study highlights novel aspects of fe s mineralization within tidal wetlands that have been drained and re flooded in contrast to normal undisturbed tidal wetlands as such the long term biogeochemical trajectory of drained and acidified wetlands that are remediated by tidal re flooding cannot be predicted from the well studied behaviour of normal tidal wetlands

importance of the assimilation of argo float measurements on the meridional overturning circulation in the south atlantic 1 the meridional overturning circulation moc and meridional heat transport mht obtained from two gfdl coupled models with and without data assimilation are examined and compared with observations collected at nominally 34 s in the south atlantic the results demonstrate that the performance of the geophysical fluid dynamic laboratory gfdl coupled data assimilation cda model is quite different between the two periods 1979 2002 and 2003 2007 due to the assimilation of argo data in later period the moc components from the gfdl cda during 1979 2002 are similar to those from gfdl cm2 1 ipcc simulation both give weak boundary currents and strong interior overturning transport compared to observations however after assimilating temperature and salinity profiles from the argo floats the performance of the gfdl cda is greatly improved in terms of representing the observed moc and mht structure the transports of boundary currents are twice as strong as those during pre argo period and the overturning flow in the interior region is reduced possible causes for the changes in model performance are discussed

the distribution of rare earth elements in groundwaters assessing the role of source rock composition redox changes and colloidal particles rare earth element ree dissolved organic carbon doc and trace element al mn fe sr ba u and th concentrations were measured in fourteen well water samples 0 22 m and one spring located along two transects set up in a catchment from western europe kervidy coet dan catchment france previous hydrological and hydrochemical no3 so42 investigations demonstrated that three chemically and spatially distinct groundwater types are present in this catchment which is fully confirmed by the ree and doc results these include i a shallow organic rich groundwater 4 4 doc 34 6 mg l from the wetland areas close to the river network this first groundwater type characterized by the development of temporary reducing conditions records high and variable ree contents 2 ree 16 ppb and displays slight or no negative ce anomaly ce ce 0 8 1 05 ii a shallow organic poor doc 3 mg l no3 rich groundwater type 86 8 no3 155 mg l located in the weathered schists below the hillslope domains this second type corresponds to recently recharged oxidized water and displays also high and variable ree concentrations 2 ppb ree 15 ppb but distinguish from the former by the occurrence of very strong negative ce anomalies ce ce 0 05 0 10 finally iii a deep organic poor doc 1 mg l nitrate poor no3 close to 0 2 mg l detection limit groundwater this third type corresponds to reduced water flowing into the deep fresh schists and yields low to very low ree contents ree 0 15 ppb as well as slight negative ce anomaly ce ce 0 8 to 0 9 temporal ree concentration variations were assessed using samples regularly collected over a six month period results show that the spatially distributed ce anomaly and ree pattern signatures are preserved throughout the studied period by contrast ree concentrations are quite variable through time especially in the wetland waters where the ree concentrations are seen to vary in phase with both redox changes and doc fe u and th content variations three ree rich water samples one doc rich and two doc poor were also filtered through membranes of decreasing pore size 100 000 d 30 000 d 5 000 d the results show that between about 40 to 65 of the ree present in the shallow doc poor groundwater samples are controlled by the colloidal fraction which is likely to consist in these inorganic waters of a mixture of mineral phases in the wetland groundwaters the fraction of ree controlled by microparticles is higher than 65 which confirms the predominant role of organic colloids as major ree carriers in wetland waters using the above data set in conjunction with analyses of soil samples we show that the deep ce anomalies found in the upper non organic part of the aquifer are probably not source rock inherited features most likely these anomalies arise from the oxidative precipitation of ce the very low ree content displayed by waters flooding the deep fresh schists is interpreted as due to the combined effects of i ph variation ii secondary sulfate mineral precipitation and iii the trapping of colloids borne ree by the aquifer rock pores data from wetland groundwaters show that the ree fe u and th budgets of these waters are mainly controlled by seasonal changes in redox conditions and organic matter content however unlike organic poor waters it appears difficult to relate the ce behaviour in these organic rich waters solely to redox conditions it is likely that the complexation of ce by organic colloids in the organic rich waters may mask redox changes by inhibiting the development of negative ce anomalies

varied representation of the atlantic meridional overturning across multidecadal ocean reanalyses abstract the atlantic meridional overturning circulation amoc is an integral part of the circulation in the atlantic ocean the amoc is typically characterized by the meridional streamfunction which is also an indicator of the thermohaline circulation this paper explores the mean state and long term variability of the atlantic meridional streamfunction and atlantic meridional heat transport from six multidecadal ocean reanalysis statistics based on the meridional overturning streamfunction and the meridional heat transport are computed in the same manner across the products and analyzed the maximum streamfunction values in the atlantic are located between 35 n and 50 n for the various ocean reanalyses the atlantic heat transport is greater between the greater antilles at about 20 n and 25 n similar to the observations the streamfunction and heat transport have stronger seasonality in the deep tropics in the north atlantic the annual harmonic of the streamfunction has greater amplitude in july between 40 n and 50 n even though there are differences in the mean strength of the streamfunction and the heat transport there are robust similarities in their seasonal cycle across ocean reanalyses furthermore although the year to year variability of the meridional heat transport is not consistent across products there are other aspects that are consistent the relationship between streamfunction and meridional heat transport at 30 n i e in the northern hemisphere shows greater consistency than that between streamfunction and meridional heat transport at 30 s i e in the southern hemisphere also even though the north atlantic sea surface temperature sst anomalies are greatly consistent their relationship with the meridional streamfunction is disparate however the relationship between north atlantic sst anomalies and meridional heat transport shows some consistency with respect to the meridional profile the greater numbers of temperature data assimilated may help in constraining the meridional heat transport more than the streamfunction thereby indicating the meridional heat transport to be an important field to analyze with respect to observed changes in the amoc

do archean chemical sediments record ancient seawater rare earth element patterns rare earth elements ree concentrations of archean and proterozoic chemical sediments are commonly used as proxies to study secular trends in the geochemistry of precambrian seawater in addition similarities in the ree signatures of archean chemical sediments and modern seawater have led researchers to argue that some archean rocks originated as biochemical precipitates i e microbial carbonates in shallow marine e g peritidal environments however terrestrial waters including river water and groundwater also commonly exhibit ree fractionation patterns that resemble modern seawater here we present the seawater like ree data for ground

hydrographic changes in the labrador sea 1960 2005 abstract the labrador sea has exhibited significant temperature and salinity variations over the past five decades the whole basin was extremely warm and salty between the mid 1960s and early 1970s and fresh and cold between the late 1980s and mid 1990s the full column salinity change observed between these periods is equivalent to mixing a 6 m thick freshwater layer into the water column of the early 1970s the freshening and cooling trends reversed in 1994 starting a new phase of heat and salt accumulation in the labrador sea sustained throughout the subsequent years it took only a decade for the whole water column to lose most of its excessive freshwater reinstate stratification and accumulate enough salt and heat to approach its record high salt and heat contents observed between the late 1960s and the early 1970s if the recent tendencies persist the basin s storages of salt and heat will fairly soon likely by 2008 exceed their historic highs the main process responsible for the net cooling and freshening of the labrador sea between 1987 and 1994 was deep winter convection which during this period progressively developed to its record depths it was caused by the recurrence of severe winters during these years and in its turn produced the deepest densest and most voluminous labrador sea water lsw1987 1994 ever observed the estimated annual production of this water during the period of 1987 1994 is equivalent to the average volume flux of about 4 5 sv with some individual annual rates exceeding 7 0 sv once winter convection had lost its strength in the winter of 1994 1995 the deep lsw1987 1994 layer lost communication with the mixed layer above consequently losing its volume while gaining heat and salt from the intermediate waters outside the labrador sea while the 1000 2000 m layer was steadily becoming warmer and saltier between 1994 and 2005 the upper 1000 m layer experienced another episode of cooling caused by an abrupt increase in the air sea heat fluxes in the winter of 1999 2000 this change in the atmospheric forcing resulted in fairly intense convective mixing sufficient to produce a new prominent lsw class lsw2000 penetrating deeper than 1300 m this layer was steadily sinking or deepening over the years following its production and is presently overlain by even warmer and apparently less dense water mass implying that lsw2000 is likely to follow the fate of its deeper precursor lsw1987 1994 the increasing stratification of the intermediate layer implies intensification in the baroclinic component of the boundary currents around the mid depth perimeter of the labrador sea the near bottom waters originating from the denmark strait overflow exhibit strong interannual variability featuring distinct short term basin scale events or pulses of anomalously cold and fresh water separated by warm and salty overflow modifications regardless of their sign these anomalies pass through the abyss of the labrador sea first appearing at the greenland side and then about a year later at the labrador side and in the central labrador basin the northeast atlantic deep water 2500 3200 m originating from the iceland scotland overflow water reached its historically freshest state in the 2000 2001 period and has been steadily becoming saltier since then it is argued that lsw1987 1994 significantly contributed to the freshening density decrease and volume loss experienced by this water mass between the late 1960s and the mid 1990s via the increased entrainment of freshening lsw the hydrostatic adjustment to expanding lsw or both

the development of middle rare earth element enrichments in freshwaters weathering of phosphate minerals abstract many phosphatic minerals of biogenic authigenic and diagenetic origin are distinguished by rare earth element ree compositions which have a well developed middle rare earth element mree enrichment defined by a gradual increase in the shale normalized ratios of ree toward the middle of the ree series la to lu also the ree composition of dissolved matter in the waters of the amazon fly and sepik rivers as well as other river lake and ground waters have well developed mree enrichments the development of mree enrichments was studied through a series of leaching experiments using river bank sediments from the amazon fly sepik and mississippi rivers a well characterized phosphate mineral rich shale with a pronounced mree enrichment in its bulk composition was also leached in order to better assess the relationship between the weathering of phosphate minerals and the formation of mree enriched solutions the two leaching solutions per sediment consisted of filtered lake water at ph 5 and the same water adjusted to ph 2 leaching experiments with the four river sediments result in extensive fractionation whereby the ree compositions of the solutions develop mree enrichments from starting sediments that show no mree enrichments the ph 2 leachates have much higher concentrations of the ree and more fully developed mree enrichments than do the ph 5 leachates the mree enrichments at ph 2 usually form within an hour of starting the experiments the phosphatic shale results show that there is preferential release of large amounts of mree at ph 5 as well as at ph 2 demonstrating the weather ability of the phosphatic minerals at phs of natural freshwaters the sepik river ph 5 experiment also shows significant mree enrichment under near neutral conditions the development and retention of the mree enrichments in the leaching solutions is accompanied by an increase in dissolved phosphate concentrations although the magnitudes of the mree enrichment do not directly correlate with the percent of phosphate released the experimental data suggest that the preferential dissolution of phosphatic minerals during weathering can result in extensive ree fractionation between bulk river sediment and water leading to freshwaters with mree enrichments

decadal modulations of interhemispheric global atmospheric circulations and monsoons by the south atlantic meridional overturning circulation this study presents a physical mechanism on how low frequency variability of the south atlantic meridional heat transport samht may influence decadal variability of atmospheric circulation a multicentury simulationofacoupledgeneralcirculationmodelisusedasbasisfor theanalysis thehighlightofthefindings herein is that multidecadal variability of samht plays a key role in modulating global atmospheric circulation via its influence on interhemispheric redistributions of momentum heat and moisture weaker samht at 308s produces anomalous ocean heat divergence over the south atlantic resulting in negative ocean heat content anomalies about 15 20 years later this forces a thermally direct anomalous interhemispheric hadley circulation transporting anomalous atmospheric heat from the northern hemisphere nh to the southern hemisphere sh and moisture from the sh to the nh thereby modulating global monsoons further analysis shows that anomalous atmospheric eddies transport heat northward in both hemispheres producing eddy heat flux convergence divergence in the nh sh around 158 308 reinforcing the anomalous hadley circulation the effectofeddies onthe nh sh polewardof308 depicts heat flux divergence convergence whichmust be balanced by sinking rising motion consistent with a poleward equatorward displacement of the jet stream this study illustrates that decadal variations of samht could modulate the strength of global monsoons with 15 20 years of lead time suggesting that samht is a potential predictor of global monsoon variability a similar mechanistic link exists between the north atlantic meridional heat transport namht at 308 na nd global monsoons

temporal variability of the south atlantic meridional overturning circulation between 20 s and 35 s altimetry derived synthetic temperature and salinity profiles between 20 s and 34 5 s are used to estimate the meridional overturning circulation moc and meridional heat transport mht which are assessed against estimates obtained from expendable bathythermograph xbt measurements consistent with studies from xbts and argo data both the geostrophic and ekman contributions to the moc exhibit annual cycles and play an equal role in the moc seasonal variations the strongest variations on seasonal and interannual time scales in our study region are found at 34 5 s the dominance of the geostrophic and ekman components on the interannual variations in the moc and mht varies with time and latitude with the geostrophic component being dominant during 1993 2006 and the ekman component dominant between 2006 and 2011 at 34 5 s

the impact of vegetation on ree fractionation in stream waters of a small forested catchment the strengbach case previous studies on waters of a streamlet in the vosges mountains eastern france have shown that strontium and rare earth elements ree mainly originate from preferential dissolution of apatite during weathering however stream water ree patterns normalized to apatite are still depleted in the light ree lree la sm pointing to the presence of an additional lree depleting process vegetation samples are strongly enriched in lree compared to stream water and their sr and nd isotopic compositions are comparable with those of apatite and stream water thus the preferential lree uptake by vegetation might lead to an additional lree depletion of surface runoff in the forested catchment mass balance calculations indicate that the yearly lree uptake by vegetation is comparable with the lree export by the streamlet and therefore might be an important factor controlling lree depletion in river water this is underlined by the observation that rivers from arctic and boreal regions with sparse vegetation appear to be less depleted in lree than rivers from tropical environments or boreal environments with a dense vegetation cover

rare earth element and stable isotope signatures of kaolin from a pliocene lateritic weathering profile at mid latitude region andalusia spain implications for paleoweathering and paleoclimatic reconstructions abstract this study reports the impact of weathering on behavior of rare earth elements ree in a coastal lateritic profile developed on pliocene sediments at mid latitude location 37 n in the guadalquivir basin spain it also explores the stable isotope signature of kaolinite providing constraints on paleotemperature and isotopic composition of the ancient meteoric water the paleoweathering profile 20 m thick comprises a white sandy clayey saprolite overlain by a red mottled clay zone which in turn is capped by a pisolitic ferricrete the kaolinitic regolith was practically reduced to a mixture of kaolinite and quartz by intense chemical weathering under warm and seasonally humid climate the kaolinized material is markedly depleted in total ree mean value of 77 30 mg kg 1 in the white saprolite and 72 70 mg kg 1 in the mottled zone relative to the parent rock 168 96 mg kg 1 development of acidic and oxidizing conditions promoted a suitable soil environment for ree release and leaching with percolating rainwater leading to an apparent loss of ree from the profile up to 87 the parent rock normalized ree patterns display concave upward shapes tracing a remarkable depletion in middle ree mree with no significant anomalies the ree concentrations normalized against the north american shale composite nasc showed consistently similar fractionation patterns the mree depleted signature nasc normalized ratios of la sm up to 3 32 and gd lu as low as 0 45 probably arises from reductive dissolution of iron oxyhydroxide phases due to seasonal water saturation as indicated from redoximorphic features the the lateritic weathering profiles evolved during the mid pliocene warm period in the southwestern iberian margin could be useful for predicting potential future environmental effects of increased atmospheric co2 on the earth s critical zone

supergene sulphate minerals from the burning coal mining dumps in the upper silesian coal basin south poland abstract sulphate minerals of various chemical compositions form subtle mixtures of small aggregated crystals on some burning coal mining dumps in the upper silesian coal basin poland they include na and mg sulphates blodite and konyaite magnesium sulphates belong to the second group and hexahydrite is its most common representative aluminium sulphates include tamarugite pickeringite and alunogen iron sulphates are copiapite group minerals metavoltine butlerite and voltaite group minerals calcium sulphates are almost exclusively represented by gypsum eds proved to be in general a better tool than wds for the chemical analysis of the sulphates both the rietveld and pawley methods were found to be useful in the calculation of unit cell parameters the analysed sulphates contain some rare and interesting elements the most important being tl ga in cd se and as the sulphates formed as a result of the mutual action of various supergene processes including the oxidation of s rich coal fire gases metal leaching from waste rocks by h2so4 solutions and evaporation the complexity of the sulphate efflorescence composition is explained by the chaotic nature of settings involving a variety of waste rocks hydration dehydration reactions and access of both ground and rain water and atmospheric oxygen

temporal variability of the atlantic meridional overturning circulation at 26 5 n the vigor of atlantic meridional overturning circulation moc is thought to be vulnerable to global warming but its short term temporal variability is unknown so changes inferred from sparse observations on the decadal time scale of recent climate change are uncertain we combine continuous measurements of the moc beginning in 2004 using the purposefully designed transatlantic rapid climate change array of moored instruments deployed along 26 5 n with time series of gulf stream transport and surface layer ekman transport to quantify its intra annual variability the year long average overturning is 18 7 5 6 sverdrups sv range 4 0 to 34 9 sv where 1 sv a flow of ocean water of 106 cubic meters per second interannual changes in the overturning can be monitored with a resolution of 1 5 sv

mobility and fractionation of rare earth elements during supergene weathering and gossan formation and chemical modification of massive sulfide gossan primary massive sulfide gossans msg in the bathurst mining camp bmc new brunswick canada are characterized by relative enrichment of au sb and as formation of jarosite group minerals jarosite plumbojarosite and argentojarosite and little or no fractionation in the rare earth elements ree including preservation of large positive eu anomalies average eu eu nasc 4 14 in msg 6 61 in massive sulfide mineralization 0 60 in host rocks the chemical and mineralogical characteristics of msg e g halfmile lake deposit imply low ph 3 and relatively oxidizing conditions during gossan formation oxidation of a volcanogenic massive sulfide body comprising pyrite pyrrhotite sphalerite galena and chalcopyrite with a falling water table the lack of light ree or heavy ree fractionation and preservation of positive eu anomalies characteristic of the original 465 ma hydrothermal fluid is consistent with relatively large water rock ratios during massive sulfide mineralization oxidation and removal of the ree predominantly as sulfate complexes lnso4 ln so4 2 low ph groundwaters recovered from past producing mines in the bmc display ree patterns reflecting those inferred to have occurred during gossan formation gossan at the restigouche deposit in contrast to the halfmile lake deposit displays mineralogical and chemical evidence for having been chemically reworked since primary gossan formation evidence for chemical reworking includes loss of primary massive sulfide mineralization textures replacement of plumbojarosite with anglesite almost complete removal of jarosite minerals loss of au sb and as and apparent preferential removal of eu resulting in loss of positive eu anomalies for most samples average eu eu nasc 1 21 in the gossan with many displaying strong negative anomalies 3 65 in massive sulfide mineralization 0 54 in host rocks based on geochemical modeling conditions inferred for the chemical reworking of the restigouche deposit include near neutral conditions and either relatively oxidizing conditions with eu2 hosted in a preferentially weathered mineral host possibly through substitution for pb in plumbojarosite and beudantite or cycling between reduced and oxidized conditions during gossan reworking

observations on the relationship between the antarctic coastal diatoms thalassiosira antarctica comber and porosira glacialis grunow jorgensen and sea ice concentrations during the late quaternary the available ecological and palaeoecological information for two sea ice related marine diatoms bacillariophyceae thalassiosira antarctica comber and porosira glacialis grunow jorgensen suggests that these two species have similar sea surface temperature sst sea surface salinity sss and sea ice proximity preferences from phytoplankton observations both are described as summer or autumn bloom species commonly found in low sst waters associated with sea ice although rarely within the ice both species form resting spores rs as irradiance decreases sst falls and sss increases in response to freezing ice in autumn recent work analysing late quaternary seasonally laminated diatom ooze from coastal antarctic sites has revealed that sub laminae dominated either by t antarctica rs or by p glacialis rs are nearly always deposited as the last sediment increment of the year interpreted as representing autumn flux in this study we focus on sites from the east antarctic margin and show that there is a spatial and temporal separation in whether t antarctica rs or p glacialis rs form the autumnal sub laminae for instance in deglacial sediments from the mertz ninnis trough george v coast p glacialis rs form the sub laminae whereas in similar age sediments from iceberg alley mac robertson shelf t antarctica rs dominate the autumn sub lamina in the dumont d urville trough adelie land mid holocene hypsithermal warm period autumnal sub laminae are dominated by t antarctica rs whereas late holocene neoglacial cool period sub laminae are dominated by p glacialis rs these observations from late quaternary seasonally laminated sediments would appear to indicate that p glacialis prefers slightly cooler ocean climate conditions than t antarctica we test this relationship against two down core holocene quantitative diatom abundance records from dumont d urville trough and svenner channel princess elizabeth land and compare the results with sst and sea ice concentration results of an antarctic and southern ocean holocene climate simulation that used a coupled atmosphere sea ice vegation model forced with orbital parameters and greenhouse gas concentrations we find that abundance of p glacialis rs is favoured by higher winter and spring sea ice concentrations and that a climatically sensitive threshold exists between the abundance of p glacialis rs and t antarctica rs in the sediments an increase to 0 1 for the ratio of p glacialis rs t antarctica rs indicates a change to increased winter sea ice concentration to 80 concentration cooler spring seasons with increased sea ice slightly warmer autumn seasons with less sea ice and a change from 7 5 months annual sea ice cover at a site to much greater than 7 5 months in the east antarctic sediment record an increase in the ratio from 0 1 to above 0 1 occurs at the transition from the warmer hypsithermal climate into the cooler neoglacial climate 4 cal kyr indicating that the ratio between these two diatoms has the potential to be used as a semi quantitative climate proxy

a summer phytoplankton bloom triggered by high wind events in the labrador sea july 2006 1 the mechanisms of nutrient resupply for an episodic phytoplankton bloom observed in the central labrador sea in july 2006 were investigated two physical processes mixed layer deepening and ekman pumping are proposed to account for the implied nutrient replenishment the nutrient flux and chlorophyll concentration before and during the bloom were estimated from a simple coupled nitrate phytoplankton model the model results show that the enrichment of nutrients in the euphotic layer and the subsequent bloom were related to two wind events storms in the period july 7 10 as the mixed layer deepened nutrient from below the nitricline were entrained into the euphotic zone the ekman pumping which was most intense at the storm centre enhanced the transport of the nutrients by raising the nitricline however ekman pumping alone was not able to transport sufficient nitrate to the euphotic layer to support the observed phytoplankton bloom

interannual variations in the atlantic meridional overturning circulation and its relationship with the net northward heat transport in the south atlantic 1 variability of the atlantic meridional overturning circulation amoc and its effect on the net northward heat transport nht in the south atlantic are examined using a trans basin expendable bathythermograph xbt high density line at 35s ax18 the time mean amoc is 17 9 2 2 sv during 2002 2007 although the geostrophic transport dominates the time mean amoc both geostrophic and ekman transports are important in explaining the amoc variability the contributions of geostrophic and ekman transports to the amoc show annual cycles but they are out ofphase resultinginweakseasonalvariabilityoftheamoc the nht variability is significantly correlated with the amoc where a 1 sv increase in the amoc would yield a 0 05 0 01 pw increase in the nht partition of transport into the western and eastern boundaries and interior suggests that to quantify changes in the amoc and nht it is critical to monitor all three regions citation dong s s garzoli m baringer c meinen andg goni 2009 interannualvariations intheatlanticmeridionaloverturningcirculationanditsrelationship with the net northward heat transport in the south atlantic geophys res lett 36 l20606 doi 10 1029 2009gl039356

looking for jarosite on mars the low temperature crystal structure of jarosite single crystal diffraction of jarosite kfe 3 3 so 4 2 oh 6 has been undertaken at low temperatures that proxy for martian surface conditions room temperature data are consistent with literature data a 7 2913 5 c 17 1744 17 and v 790 72 11 in r 3 m while the first low temperature data for the mineral is presented at 253 213 173 and 133 k data collections between 297 and 133 k show strongly anisotropic thermal expansion with the c axis much more expandable than the a axis much of the anisotropy is due to strong distortion of the ko 12 polyhedron which increases by 8 between 297 and 133 k the data sets can aid in the identification of jarosite by x ray diffraction of martian soils using the curiosity rover s chemin instrument