seasonality of dissolved rare earth elements in the lower mississippi river 1 dissolved rare earth element ree concentrations were determined in a 27 month time series of the lower mississippi river overall the results agree with limited previous investigations that is the river shows enrichment of heavy rees relative to light rees and also has a significant ce anomaly however the previous investigations relied on only single samples from the river this seasonal investigation reveals significant temporal variations in the river s ree chemistry in particular large approximately fivefold variations in light ree concentrations are observed the light rees follow a seasonality similar to particle reactive trace elements also the ce anomaly shows a corresponding seasonality with greatest fractionation when dissolved concentrations are lowest the time series encompassed a period of extreme flooding in the u s midwest however this event did not appear to affect dissolved ree concentrations the results of this study are compatible with previous observations of dissolved trace elements in the lower mississippi river which suggested the importance of redox processes within the river system in controlling seasonal concentration variability for many of these elements additionally speciation modeling indicates that carbonate complexes likely dominate the solution chemistry of rees in the lower mississippi the observed behavior of the dissolved rees is likewise compatible with this speciation

rare earth elements and neodymium isotopes in sedimentary organic matter abstract we report rare earth element ree and neodymium nd isotope data for the organic fraction of sediments collected from various depositional environments i e rivers n 25 estuaries n 18 open ocean settings n 15 and cold seeps n 12 sedimentary organic matter som was extracted using a mixed hydrogen peroxide nitric acid solution 20 h2o2 0 02 m hno3 after removal of carbonate and oxy hydroxide phases with dilute hydrochloric acid 0 25 m hcl a series of experimental tests indicate that extraction of sedimentary organic compounds using h2o2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates however this contamination is expected to be minor for ree because measured concentrations in h2o2 leachates are about two orders of magnitude higher than in the above mentioned phases the mean ree concentrations determined in the h2o2 leachates for samples from rivers estuaries coastal seas and open ocean settings yield relatively similar levels with ree 109 86 ppm mean s n 58 the organic fractions leached from cold seep sediments display even higher concentration levels 285 150 ppm mean s n 12 the h2o2 leachates for most sediments exhibit remarkably similar shale normalized ree patterns all characterized by a mid ree enrichment compared to the other ree this suggests that the distribution of ree in leached sedimentary organic phases is controlled primarily by biogeochemical processes rather than by the composition of the source from which they derive e g pore river or sea water the nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions in contrast the som extracted from marine sediments display end values that typically range between the end signatures for terrestrial organic matter inferred from the analysis of the sedimentary detrital fractions and marine organic matter inferred from the analysis of local surface seawater a notable exception is the case of organic matter om fractions leached from cold seep sediment samples which sometimes exhibit end values markedly different from both terrigenous and surface seawater signatures this suggests that a significant fraction of organic compounds in these sediments may be derived from chemosynthetic processes recycling pore water ree characterized by a distinct isotopic composition overall our results confirm that organic matter probably plays an important role in the oceanic ree budget through direct scavenging and remineralization within the water column both the high ree abundances and the shape of shale normalized patterns for leached som also suggest that om degradation in sub surface marine sediments during early diagenesis could control to a large extent the distribution of ree in pore waters benthic fluxes of organic bound ree could hence substantially contribute to the exchange processes between particulates and seawater that take place at ocean margins neodymium isotopes could provide useful information for tracing the origin terrestrial versus marine and geographical provenance of organic matter with potential applications in paleoceanography in particular future studies should further investigate the potential of nd isotopes in organic compounds preserved in sedimentary records for reconstructing past variations of surface ocean circulation

colloidal rare earth elements in a boreal river changing sources and distributions during the spring flood abstract variations in the physico chemical speciation of the rare earth elements ree have been investigated in a subarctic boreal river during an intense spring flood event using prefiltered

seasonal variations in the geochemistry of shallow groundwater hosted in granitic till the groundwater chemistry in a small catchment in northern sweden has been studied for a period of 15 months including two snowmelt events the groundwater was sampled from two wells in a slope

size characteristics of chromophoric dissolved organic matter in the chukchi sea with the arctic warming terrestrial input plays a more important role in carbon cycle in the arctic ocean than before chromophoric dissolved organic matter cdom as a tracer of terrestrial dissolved organic matter tdom becomes more valuable in elucidating the source and compositions of dom although measurements of dom in the arctic ocean have been widely reported characteristics of high molecular weight colloids are still poorly understood in this study the bulk absorbance and size fractograms of cdom were measured in the chukchi seas using an asymmetrical flow field flow fractionation af4 coupled online with uv vis detectors both cdom a254 absorption coefficient at 254 nm and the integrated uv254 from af4 uv vis detector of three colloidal fractions 1 10 kda 10 100 kda 100 kda significantly correlated with the fraction of meteoric water fmw calculated from 18o in seawater which indicates that the cdom was mainly derived from terrestrial input and a254 is a potential tracer of tdom in the chukchi sea compared with the larger colloidal fractions 10 100 kda and 100 kda the smaller colloidal fraction 1 10 kda showed a stronger correlation with the fmw suggesting the smaller colloids were of mostly terrigenous origin values of field measured spectral slope at 275 295 nm s275 295 a tdom proxy were significantly lower than the model estimated s275 295 calculated from the modis aqu satellite remote sensing data which indicated that terrestrial input of cdom derived from model calculation was likely underestimated in the chukchi sea this article is protected by copyright all rights reserved

rare earth elements ree and yttrium in stream waters stream sediments and fe mn oxyhydroxides fractionation speciation and controls over ree y patterns in the surface environment we have collected 500 stream waters and associated bed load sediments over an 400 km 2 region of eastern canada and analyzed these samples for fe mn and the rare earth elements ree y in addition to analyzing the stream sediments by total digestion multi acid dissolution with metaborate fusion we also leached the sediments with 0 25 m hydroxylamine hydrochloride in 0 05 m hcl to determine the ree y associated with amorphous fe and mn oxyhydroxide phases we are thus able to partition the ree into dissolved 0 45 lm labile hydroxylamine and detrital sediment fractions to investigate ree fractionation and in particular with respect to the development of ce and eu anomalies in oxygenated surface environments surface waters are typically lree depleted la sm nasc ranges from 0 16 to 5 84 average 0 604 n 410 where the ree are normalized to the north america shale composite have strongly negative ce anomalies ce ce nasc ranges from 0 02 to 1 25 average 0 277 n 354 and commonly have positive eu anomalies eu eu nasc ranges from 0 295 to 1 77 average 0 764 n 84 in contrast the total sediment have flatter ree y patterns relative to nasc la sm nasc ranges from 0 352 to 1 12 average 0 778 n 451 and are slightly middle ree enriched gd yb nasc ranges from 0 55 to 3 75 average 1 42 most total sediments have negative ce and eu anomalies ce ce nasc ranges from 0 097 to 2 12 average 0 799 and eu eu nasc ranges from 0 39 to 1 43 average 0 802 the partial extraction sediments are commonly less lree depleted than the total sediments la sm nasc ranges from 0 24 to 3 31 average 0 901 n 4537 more mree enriched gd yb nasc ranges from 0 765 to 6 28 average 1 97 and ce and eu anomalies negative and positive are more pronounced the partial extraction recovered on average 20 of the fe in the total sediment 80 of the mn and 21 29 of the rees ce 19 and y 32 comparison between rees in water partial extraction and total sediment analyses indicates that rees y in the stream sediments have two primary sources the host lithologies i e mechanical dispersion and hydromorphically transported the labile fraction furthermore eu appears to be more mobile than the other ree whereas ce is preferentially removed from solution and accumulates in the stream sediments in a less labile form than the other rees y despite poor statistical correlations between the rees y and mn in either the total sediment or partial extractions based on apparent distribution coefficients and the ph of the stream waters we suggest that either sediment organic matter and or possibly d mno2 feooh are likely the predominant sinks for ce and to a lesser extent the other ree in the stream sediments

organic and organo mineral colloids in discontinuous permafrost zone on going permafrost thaw in discontinuous permafrost regions produces significant amounts of small permafrost subsidence and depressions while large lakes are likely to drain into streams and rivers the intensification of permafrost thaw may alter the size distribution and chemical composition of organo fe al colloids in lakes and rivers we used a continuum of surface water bodies from permafrost subsidence small depressions and thaw ponds to large lakes and rivers that drain the western siberia lowland wsl to assess oc major and the trace element size distribution between the 20 m 5 m 1 2 m 0 45 m 0 22 m 0 025 m and 1 kda 1 4 nm size fractions this approach allowed us to distinguish the organic and organo ferric colloids that were responsible for the transport of trace elements in surface waters and address their evolution during possible physico chemical and biological processes both conventionally dissolved 0 22 m and low molecular weight 1 kda fractions exhibited an order of magnitude decrease in doc fe in the landscape continuum depressions and permafrost subsidence thaw ponds thermokarst lakes streams rivers thermodynamic modeling and on site size separation suggested that a number of trace elements tes including alkaline earth elements and several micronutrients zn ba mn and ni decreased the degree of their binding to dom along the landscape continuum whereas the majority of insoluble tes al fe co cd cu pb rees th and u remained complexed with dom in the lmw 1 kda fraction two primary sites of colloid generation included i ground vegetation and peat leaching which supplied dom complexes of divalent metals and organo al entities to thaw ponds and lakes and ii fe2 oxidation and te co precipitation with fe hydroxides in the presence of surface dom at groundwater discharge sites within the riparian hyporheic zones of rivers under a warming climate scenario an increase in the thickness of the thawing depth will intensify the input of inorganic components from deep mineral horizons and possibly underground waters thus producing the enrichment of large lakes in fe rich colloids and particles the speciation of divalent metal micronutrients cu ni and co and toxic metals al cd pb and u that are complexed within dom will most likely remain conservative overall the wsl s surface water colloidal composition may shift from dom rich and dom al rich to fe rich and the export of low soluble trivalent and tetravalent hydrolysates from the soil to rivers will increase

chemical evolution of rare earth elements fractionation between colloidal and solution phases of filtered river water abstract within the dissolved fraction of connecticut river water there is large scale fractionation of rare earth elements between colloidal and solution phases colloidal particles carry a large part of the dissolved ree pool filtration through filters with progressively smaller pore size 0 45 0 22 and 0 025 m results in filtrates with lower absolute concentrations of ree and more fractionated compositions with decreasing pore size the filtrates have shale normalized abundances which become systematically more depleted in the lree relative to the hree hence both the solution and colloidal phases are significantly fractionated with respect to the dissolved fraction these conclusions are consistent with previous studies of ree in rivers estuaries and soils and with surface solution speciation models colloids play an important role in the aquatic geochemistry of rare earth elements they are responsible for the fractionation of ree during the estuarine removal of ree the removal of suspended and colloidal particles from river water leaves the solution phase of river water with compositions of ree as evolved as those of surface seawater hence the evolution of the composition of ree in river water and seawater is significantly influenced by colloid formation during chemical weathering on the continents

carbon export and cycling by the yukon tanana and porcupine rivers alaska 2001 2005 1 loads and yields of dissolved and particulate organic and inorganic carbon doc poc dic pic were measured and modeled at three locations on the yukon river yr and on the tanana and porcupine rivers tr pr in alaska during 2001 2005 total yr carbon export averaged 7 8 tg c yr 1 30 as oc and 70 as ic total c yields 0 39 1 03 mol c m 2 yr 1 were proportional to water yields 139 356 mm yr 1 r2 0 84 at all locations summer doc had an aged component fraction modern fm 0 94 0 97 except in the permafrost wetland dominated pr where doc was modern poc had fm 0 63 0 70 doc had high concentration high aromaticity and high hydrophobic content in spring and low concentration low aromaticity and high hydrophilic content in winter about half of annual doc export occurred during spring dic concentration and isotopic composition were strongly affected by dissolution of suspended carbonates in glacial meltwater during summer

rare earth element behavior in soils and salt pan sediments of a semi arid granitic terrain in the western cape south africa the rare earth element ree contents of soils and pan sediments of the darling hills granitic terrain of southwestern south africa were determined to study the behavior of ree during weathering in a semi arid mediterranean climate the p rich stype bedrock granite has a middle ree mree enrichment relative to post archean australian sedimentary rocks paas that primarily reflects the ree content of feldspar and accessory apatite initial chemical weathering of the granite results in the loss of ree particularly ce eu and the heavy ree hree the enrichment of ree in soils relative to bedrock granite corresponds to clay mineral and amorphous fe oxide content in the case of the light ree lree and precipitation of pedogenic calcite in the case of the hree quartz sand dilutes the ree content and concentration of k feldspar produces positive eu anomalies cerium is rapidly precipitated during weathering and retained in clayey upper soil horizons as insoluble ceo2 most pan sediments have a bowl shaped ree pattern that is derived from the accumulation of eroded catchment soils modified by precipitation of evaporative carbonates ree enrichment particularly lree and the large negative ce anomaly of oxidized basal pan sediment relative to the bedrock granite suggest that ree entering the pan by groundwater flow are sorbed onto amorphous fe oxides in contrast goethite rich nodules from the pan have a low ree content and show hree enrichment relative to the granite precipitation of pedogenic calcite and evaporative pan carbonates greatly increases the retention of the hree in these semi arid soils diagenetic pan dolomite has a ree pattern similar to pedogenic and evaporative calcite but with a significantly lower ree content the ree patterns indicate that although most abundant in the bedrock granite the mree are least retained by soils during weathering the lree are generally retained by clayey and amorphous fe oxide rich soils and sediments whereas hree are retained by precipitation of soil and pan carbonates d 2003 elsevier b v all rights reserved

sources and physical processes responsible for oh h2o in the lunar soil as revealed by the moon mineralogy mapper m3 1 analysis of two absorption features near 3 m in the lunar reflectance spectrum observed by the orbiting m3 spectrometer and interpreted as being due to oh and h2o is presented and the results are used to discuss the processes producing these molecules this analysis focuses on the dependence of the absorptions on lunar physical properties including composition illumination latitude and temperature solar wind proton induced hydroxylation is proposed as the creation process and its products could be a source for other reported types of hydrogen rich material and water the irregular and damaged fine grained lunar soil seems especially adapted for trapping solar wind protons and forming oh owing to abundant dangling oxygen bonds the m3 data reveal that the strengths of the two absorptions are correlated and widespread and both are correlated with lunar composition but in different ways feldspathic material seems richer in oh these results seem to rule out water from the lunar interior and cometary infall as major sources there appear to be correlations of apparent band strengths with time of day and lighting conditions however thermal emission from the moon reduces the apparent strengths of the m3 absorptions and its removal is not yet completely successful further many of the lunar physical properties are themselves intercorrelated and so separating these dependencies on the absorptions is difficult due to the incomplete m3 data set this process should also operate on other airless silicate surfaces such as mercury and vesta which will be visited by the dawn spacecraft in mid 2011

mobility of rare earth elements during weathering of till in northern sweden abstract continuous volume controlled sampling from the surface down to a depth of 130 cm was conducted at two stations on weathered till typic haplocryods all the samples were analysed for major and trace elements including the rare earth elements ree eight thousand seven hundred years of weathering since the glacial ice left the area has resulted in a strong depletion of ree in the e horizon this loss decreases as atomic number increases so that 80 85 of the la and 54 60 of the yb have been lost europium has been lost to a greater degree than have the neighbouring elements possible explanations for the release of ree are weathering of common silicates such as hornblende and epidote and plagioclase in the case of eu weathering of apatite weathering of rare but ree rich minerals such as allanite and monazite and release of ree adsorbed on clay minerals further studies on various size fractions and minerals are needed to quantify the importance of the various possible mechanisms of ree release the release of ree continues within and below the bs1 horizon but the results from one station show that light ree can be enriched in the bs1 horizon this secondary enrichment could be caused by adsorption on secondary oxy hydroxides on clay minerals or on organic material however the net result of the weathering is that all ree have been released to the groundwater

rare earth elements in river waters we measured rare earth element ree concentrations in river waters to characterize the suspended and dissolved river flux of the ree to the oceans the ree pattern of river suspended materials is sensitive to drainage basin geology a positive correlation is observed between la yb ratios and nd model ages for the rivers studied major rivers have light ree enriched patterns relative to the north american shale composite nasc with la yb n 1 6 2 7 river water dissolved material 0 2 m is heavy ree enriched relative to suspended material and the most pronounced negative ce anomalies occur in rivers of high ph light ree concentrations vary by approximately 3 orders of magnitude and are inversely related to ph and major cation concentrations from these data we estimate that typical major river runoff has heavy ree depleted suspended material with la yb n 1 9 we conclude that the terrigenous input to the oceans from major rivers is heavy ree depleted relative to shales from the available data average river water dissolved material appears to be heavy ree enriched with la yb n 0 4 estuarine removal processes lower the dissolved ree river flux by approximately 60 and result in a flux that is more heavy ree enriched with la yb n 0 2 calculated oceanic residence times with respect to river input range from 2300 to 21 000 years are shortest for ce and greatest for the heavy ree and la such long residence times may suggest the presence of additional sources of ree in seawater

submarine groundwater discharge of rare earth elements to a tidally mixed estuary in southern rhode island abstract rare earth element ree concentrations were analyzed in surface water and submarine groundwater within the pettaquamscutt estuary located on the western edge of narragansett bay in rhode island these water samples were collected along the salinity gradient of the estuary rare earth element concentrations in the majority of the groundwater samples are substantially higher than their concentrations in the surface waters in particular nd concentrations in groundwater range from 0 43 nmol kg 1 up to 198 nmol kg 1 mean sd 42 1 87 2 nmol kg 1 whereas nd concentrations range between 259 pmol kg 1 and 649 pmol kg 1 mean sd 421 149 pmol kg 1 in surface waters from the estuary which is on average 100 fold lower than nd in the groundwaters groundwater samples all exhibit broadly similar middle ree mree enriched shale normalized ree patterns despite the wide variation in ph of these natural waters 4 87 ph 8 13 the similarity of the shale normalized ree patterns across the observed ph range suggests that weathering of accessory minerals such as apatite and or precipitation of lree enriched secondary phosphate minerals controls groundwater ree concentrations and fractionation patterns more specifically geochemical mixing models suggest that the ree fractionation patterns of the surface waters may be controlled by ree phosphate mineral precipitation during the mixing of groundwater and stream water with incoming water from the rhode island sound the estimated sgd submarine groundwater discharge of nd to the pettaquamscutt estuary is 26 11 mmol nd day 1 which is in reasonable agreement with the nd flux of the primary surface water source to the estuary the gilbert stuart stream i e 36 mmol day 1 and of the same order of magnitude for a site in florida

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

rare earth elements in the sediments of lake baikal lake baikal is the deepest and probably oldest lake on earth its water column is pervasively oxic and sedimentation rates are very low which leads to the formation of a dynamic iron fe and manganese mn enrichment below the mn ii o2 boundary these often massive accumulations can be buried within the reducing part of the sediments and give rise to complex and cryptic redox cycles the mobility of rare earth elements rees is influenced by the dissolution and reduction dynamics of the ferromanganese oxides the present study offers an overview of the ree chemistry in lake baikal and its catchment area and more specifically ree distribution in five 11 to 26 cm long sediment cores situated across the lake at different water depths we analysed and discussed normalised ree patterns and their consequential cerium ce anomalies while particulate ree concentrations are mainly influenced by processes above or near the surface of lake baikal such as the development of a widespread negative ce anomaly processes occurring during early diagenesis in the sediment are most reflected in pore water rees the dissolution of ferromanganese oxides at the mn ii o2 boundary remobilizes significant amounts of ree into the pore water whereby some are likely adsorbed onto colloidal fe oxides however besides the tendency of ce being associated with mn oxides pore water rees fractionate predominantly around the buried fe mn accumulation where light rees preferentially adsorb onto fe oxides

temporal variations in dissolved and suspended iron and manganese in the kalix river northern sweden abstract particulate and dissolved fe and mn were measured once a week from may to september 1982 in the kalix river north sweden during winter baseflow the dissolved fe concentration was 450 g l 1 early snow melt discharge increased the concentration slightly but during springflood maximum the concentration decreased to a minimum value of 60 g l 1 in mid july particulate matter in the kalix river is dominated by fe which ranges between 14 and 38 of the ashed suspended load 70 80 of the total fe load being retained by 0 45 m filters approximately 10 of particulate fe can be accounted for by a detrital phase the particulate fe al ratio showed a mean value of 6 5 which is more than ten times the ratio in mean world river particulate fe showed a peak during early snowmelt and decreased during maximum discharge similar to dissolved fe dissolved mn concentrations ranged from 1 1 to 53 4 m l 1 with a mean value of 11 2 12 4 g l 1 whereas particulate mn ranged from 3 1 ti 18 2 g l 1 with a mean concentration of 10 6 4 9 g l 1 during may and june most mn was transported in the dissolved phase whereas in july and august the particulate fraction dominated there was a drastic increase in non detrital particulate mn with a concomitant decrease in the dissolved fraction in early july with peak values in mid july and early august the decrease in dissolved mn and increase of particulate mn is probably the consequence of two processes namely addition of non detrital particulate mn to the river possibly from lakes and transformation of dissolved mn to a particulate phase within the river a combination of increased ph temperature and particulate mn triggered the precipitation of dissolved mn although the significance of each factor can not be evaluated from this study

the sedimentary flux of dissolved rare earth elements to the ocean abstract we determined pore fluid rare earth element ree concentrations in near surface sediments retrieved from the continental margin off oregon and california usa these sites represent shelf to slope settings which lie above within and below the oxygen minimum zone of the northeast pacific the sediments are characterized by varying degrees of net iron reduction with pore fluids from the shelf sites being generally ferruginous and the slope sediments having less pronounced iron reduction zones that originate deeper in the sediment package ree concentrations show maxima in shallow upper 2 10 cm subsurface pore fluids across all sites with concentrations that rise more than two orders of magnitude higher than seawater these pore fluid enrichments highlight the importance of a sedimentary source of rees to the ocean s water column here we use our measurements to estimate the diffusive flux of nd out of ocean sediments resulting in a global flux between 18 and 110 10 6 mol nd yr 1 while we do assume that our pore fluid profiles as well as the very limited data previously published are representative of a wide array of ocean environments this calculated flux can account for the modeled missing nd source flux 76 10 6 mol nd yr 1 in global budgets arsouze et al 2009 pore fluid normalized ree patterns show distinct variation in the middle ree and heavy ree enrichments with sediment depth and amongst sites these patterns show that the heavy ree enrichment of pore fluids at our deep slope site 3000 m water depth is closest to the heavy ree enrichment of seawater this observation supports the view that ree cycling within the upper ten centimeters of deep sea marine sediments as opposed to shallower continental shelf and slope sediments plays a significant role in controlling the integrated global ree flux from the pore fluids and consequently the broad scale ree pattern in seawater

binding and transport of rare earth elements by organic and iron rich nanocolloids in alaskan rivers as revealed by field flow fractionation and icp ms abstract water samples were collected from six small rivers in the yukon river basin in central alaska to examine the role of nanocolloids 0 5 40 nm in the dynamics and transport of rare earth elements rees in northern high latitude watersheds influenced by permafrost total dissolved 40 nm colloids in a river sampled at higher altitude the

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

the termination of the equatorial undercurrent in the eastern pacific abstract the termination of the equatorial undercurrent euc in the eastern tropical pacific has been studied through analysis of the historical hydrographic station data in the region bounded by 5 n 10 s 80 w and 100 w three distinctive hydrographic features associated with the euc are used along with dynamic topography to trace the mean path of the euc and to investigate aspects of its seasonal variation these features are 1 the 13 c thermostad 2 the high salinity core and 3 the high dissolved oxygen concentration tongue the thermostad is thickest just south of the equator to the west of the galapagos islands with a decreasing maximum extending southeast to the coast of south america near 7 s the thermostad is poorly developed in the mean near the equator east of the galapagos islands this pattern appears to be produced by convergence of eastward flow in the euc and in the southern subsurface countercurrent as the euc flows southeastward from the galapagos this interpretation is supported by the geostrophic flow calculated from the mean dynamic topography the isolated high salinity core is found to the south of the equator and is traced all the way to the coast of south america the high oxygen tongue associated with the euc splits at the galapagos with the southward projecting branch disappearing rapidly as an identifiable feature the other branch of the tongue continues around the islands to the north and along the equator to the coast of ecuador some evidence of recirculation of euc water in the south equatorial current is seen to the northwest of the galapagos a strong seasonal pulsation of the euc affects these features in a consistent way with the pulse occurring first west of the galapagos and later along the coast the thermostad first reaches maximum development and then a pronounced downwelling of the thermocline occurs rapidly leading to minimum thermostad extent associated wtih this downwelling is an eastward protruding high salinity tongue near the equator which is later seen as an isolated core along the coast at 4 s and 6 s pressure gradients along the equator and the coast inferred from dynamic topography suggest that this pulse is associated with an increase in the flow of the euc and ultimately the peru chile undercurrent the pressure gradient reversal along the equator occurs prior to the annual wind reversal suggesting that remote forcing plays a role in the seasonal pulse of the euc in the eastern pacific

interannual variability of the equatorial pacific revisited a linear numerical model forced by monthly shipboard wind estimates used to study the interannual response of the tropical pacific ocean for 1961 1970 busalacchi and o brien 1981 is extended through december 1978 the additional 8 years include the 1972 and 1976 los ninos and the aborted event of 1975 model pycnocline variations at several locations are compared with observed sea level fluctuations el nino events are depicted as periods when the pycnocline is persistently deep along the eastern boundary remotely forced equatorial kelvin waves are responsible for this response the character of each simulated el nino is strongly dependent on the relation between zonal wind stress changes in the western and central equatorial pacific there are important differences in the location and timing of the wind changes associated with each el nino during the 1970 s the easterlies in the central equatorial pacific had more of an active role in the evolution of el nino than in the previous decade in the western tropical pacific a rapid shoaling of the pycnocline during each el nino is caused by westward propagating rossby waves interannual pycnocline displacements in the central equatorial pacific are determined by the superposition of kelvin waves excited to the west and first horizontal mode rossby waves generated to the east

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

rare earth elements in tributaries of lake baikal siberia russia abstract ree dissolved in waters from sixty five sampled tributaries of lake baikal show diversity in abundances ree 0 02 2 16 g l and distribution patterns la yb n 0 20 5 58 la tb n 0 30 2 59 total ree contents vary seasonally and yearly while ree patterns remain generally similar the ree patterns in stream waters correlate with those in the drained rocks and hence seem to be predominantly controlled by watershed lithology rivers having small watersheds around lake baikal belong to six lithological provinces with different stream water ree patterns the olkha plateau and the ranges of primorsky baikalsky barguzin ulan burgassy and khamar daban the khamar daban province in turn is lithologically heterogeneous and comprises four subprovinces with different respective patterns of dissolved ree rock water interaction in subsurface aquifers that feed the baikal inlets provides much stronger lithological control of ree than the weak interaction of short and rapid streams with rocks on the surface ree fractionation in stream waters show negative ce anomalies in almost all samples ce anom 0 12 0 97 except for those of large rivers selenga turka barguzin upper angara and kichera the reason is that the great length relatively slow current and the presence of streambed fine alluvium make the water chemistry more uniform and the ree patterns less dependent on local variations in watershed lithology the sampled tributaries represent a range of physico chemical and geomorphological conditions which can be used as reference for calibrations in future studies of sediment sources and possibly as a valuable tool for mineral exploration

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

characterisation of fe bearing particles and colloids in the lena river basin ne russia abstract rivers are significant contributors of fe to the ocean however the characteristics of chemically reactive fe remain poorly constrained especially in large arctic rivers which drain landscapes highly susceptible to climate change and carbon cycle alteration the aim of this study was a detailed characterisation size mineralogy and speciation of riverine fe bearing particles 0 22 m and colloids 1 kda 0 22 m and their association with organic carbon oc in the lena river and tributaries which drain a catchment almost entirely underlain by permafrost samples from the main channel and tributaries representing watersheds that span a wide range in topography and lithology were taken after the spring flood in june 2013 and summer baseflow in july 2012 fe bearing particles were identified using transmission electron microscopy as large 200 nm 1 m aggregates of smaller 20 30 nm spherical colloids of chemically reactive ferrihydrite in contrast there were also large 500 nm 1 m aggregates of clay illite particles and smaller 100 200 nm iron oxide particles dominantly hematite that contain poorly reactive fe tem imaging and scanning transmission x ray microscopy stxm indicated that the ferrihydrite is present as discrete particles within networks of amorphous particulate organic carbon poc and attached to the surface of primary produced organic matter and clay particles together these larger particles act as the main carriers of nanoscale ferrihydrite in the lena river basin the chemically reactive ferrihydrite accounts for on average 70 15 of the total suspended fe in the lena river and tributaries these observations place important constraints on fe and oc cycling in the lena river catchment area and fe bearing particle transport to the arctic ocean

dissolved rare earth elements in a seasonally snow covered alpine subalpine watershed loch vale colorado dissolved rare earth elements rees were determined in a four year time series at the outlet of loch vale the loch vale watershed is a seasonally snow covered alpine subalpine basin in rocky mountain national park usa the time series was mainly distinguished by an annual early spring peak in the concentrations of all rees ree concentrations at this time were as much as 8 fold greater than at other times of the year this annual peak was coincident with an early spring peak in dissolved organic carbon doc which results from flushing of soils at the beginning of spring snow melting the ree doc peak occurs as discharge starts to increase from wintertime lows but well before the spring peak in discharge speciation considerations suggest complexation of the rees by doc the ce anomaly also increases i e is less fractionated during the spring flush indicating that the most reducing or least oxidizing ree sources in the system are comparatively more important at that time mn data and the la yb ratio also support this the behavior of rees in the loch vale system has additionally been compared with metal and doc behavior in other systems hydrologic and climatic differences can be important especially with regard to timing and duration of the spring flush peak damping of hydrologic events in the lower floodplain of major rivers may also partially result in the differences observed between loch vale and the lower mississippi river however comparison with the amazon river system additionally suggests that seasonal flooding of wetlands may be an important regulator of ree concentrations chemical differences are also important for these systems this includes ph and suspended matter concentrations which affect the balance between adsorption and complexation additionally the relative complexing ability of doc in different systems is a factor needing further consideration

a linear stratified ocean model of the equatorial undercurrent a linear stratified ocean model is used to study the wind driven response of the equatorial ocean the model is an extension of the lighthill 1969 model that allows the diffusion of heat and momentum into the deeper ocean and so can develop non trivial steady solutions to retain the ability to expand solutions into sums of vertical normal modes mixing coefficients must be inversely proportional to the square of the back ground vaisala frequency the model is also similar to the earlier homogeneous ocean model of stommel i960 he extended ekman dynamics to the equator by allowing his model to generate a barotropic pressure field the present model differs in that the presence of stratification allows the generation of a baroclinic pressure field as well the most important result of this paper is that linear theory can produce a realistic equatorial current structure the model undercurrent has a reasonable width and depth scale there is westward flow both above and below the undercurrent the meridional circulation conforms to the classical picture suggested by cromwell 1953 unlike the stommel solution the response here is less sensitive to variations of parameters ocean boundaries are not necessary for the existence of the undercurrent but are necessary for the existence of the deeper equatorial intermediate current the radiation of equatorially trapped rossby and kelvin waves is essential to the development of a realistic undercurrent because the system supports the existence of these waves low order vertical modes can very nearly adjust to sverdrup balance defined below which in a bounded ocean and for winds without curl is a state of rest as a result higher order vertical modes are much more visible in the total solution this property accounts for the surface trapping and narrow width scale of the equatorial currents the high order modes tend to be in yoshida balance defined below and generate the characteristic meridional circulation pattern associated with equatorial ekman pumping

geochemical behaviour of rare earth elements ree along a river reach receiving inputs of acid mine drainage abstract total and dissolved rare earth elements ree were studied in a river reach affected by several inputs of acid mine drainage the first four acidic discharges were of lesser importance compared to the last agrio river coming from the rio tinto mines which transported high loads of fe and al 2 1 and 4 2 ton day respectively together with ree 16 4 kg day and other trace elements in the acid mine drainage amd sources practically all the ree were dissolved and the north american shale composite nasc normalized patterns showed an enrichment in medium ree although some differences exist between the patterns of each source the ph values in the river reach upstream of the confluence with the agrio river ranged between 8 01 and 7 03 and most of the fe and al from the amd sources precipitated downstream of this acidic discharge the ph decreased to 2 98 upstream of the first amd input the dissolved and total concentrations of ree were very low 7 concentrations of ree increased up to 25 g l mainly transported by the particulate phase in the reach downstream of the agrio river with acidic conditions ree behaved conservatively the ree nasc normalized patterns of the river samples resemble that of the amd sources although an enrichment of heavy ree in the dissolved phase is observed linked to complexation by carbonates cerium and particularly la also show higher dissolved percentages similar to hree which must be due to the lower affinity of these elements to be sorbed onto fe oxyhydroxides variations in ce and eu anomalies are observed along the river reach as a consequence of the different amd inputs however the values of the ce anomaly are higher in total samples than in dissolved samples speciation results indicate that these differences are not caused by differences in oxidation states but by slight differences in the hydrogeochemical behaviour of ce with respect to la and nd

dissolved suspended and colloidal fluxes of organic carbon major and trace elements in the severnaya dvina river and its tributary abstract the chemical status of major and trace elements te and organic carbon oc has been studied in the severnaya dvina and pinega rivers draining granitic moraine carbonate and sedimentary deposits of the arkhangelsk region nw russia the white sea basin of the arctic ocean sampling was performed during winter and summer baseflow seasons and during the spring flood 2007 2008 size separation procedure included on site filtration through 5 m 0 22 m 100 10 and 1 kda and dialysis through 1 kda and 10 kda pore size membranes the organic carbon concentration in truly dissolved form trace and major element concentrations in the suspended matter of the river severnaya dvina were measured during different seasons over three years of observation based on collected data we evaluate here for the first time the seasonal fluxes of major and trace elements in the suspended 0 22 m total dissolved

hindcasts of sea level variations during the 1982 83 el nino abstract the sea level signature for the onset of the 1982 83 el nino is hindcasted using a linear wind driven model that consists of four vertical modes the hindcast solution is compared with sea level time series from 18 island and coastal stations throughout the tropical pacific the response of the first and second baroclinic modes when summed account for a significant portion of the phase and amplitude of the observed sea level the comparisons with observed sea level are best in the eastern tropical pacific along the equator and south american coast where the solutions are a function of integrals of the zonal wind field to the west the skill of the hindcast is notably less away from the equator

solid speciation and fractionation of rare earth elements in a spodosol profile from northern sweden as revealed by sequential extraction a sequential extraction has been carried out on seven soil samples from a spodosol profile in till with granitic composition the soil profile was sampled in northern sweden five fractions were selected for extraction a ch 3coona extractable exchangeable adsorbed carbonate b na 4p 2o 7 extractable labile organics c 0 25 m nh 2oh hcl extractable amorphous fe oxyhydroxides mn oxides d 1 m nh 2oh hcl extractable crystalline fe oxides and e kclo 3 hcl extractable organics and sulphides extracted rare earth elements ree were determined with high resolution icp ms in addition to the soil stream water suspended particulate matter was also analysed for ree total concentrations in the soil samples show that the ree have been fractionated during weathering in the acidic ph 4 28 e horizon all ree are depleted relative to the unweathered till the depletion decreases with increasing atomic number also in the b horizon ph 5 86 the ree are depleted although to a lesser extent compared to the e horizon secondary phases in the b horizon fractionate the ree in different ways rare earth elements extracted in extractions a and c were enriched in the intermediate ree relative to heavy and light ree if normalized to local till in extractions b and d the heavy ree were enriched relative to the light ree and in extraction e a large enrichment of light ree relative to heavy ree was found stream water suspended particulate matter is enriched in all ree relative to local till the light ree are more enriched than the heavy ree normalized la lu ratios in the suspended matter ranged from 1 5 to 2 4 and were negatively correlated with stream water discharge as well as with content of detrital inorganic matter in the suspended load the only extracted phase that potentially can explain the high normalized la lu ratio in the suspended matter is the phase extracted in extraction e which has a ratio of 2 0 4 2 the normalized la lu ratio for the rest of the extractions ranged from 0 5 to 1 2 it is concluded that organic matter seems to be important for the particulate transport of ree in northern coniferous areas

trace elements in organic and iron rich surficial fluids of the boreal zone assessing colloidal forms via dialysis and ultrafiltration on site size fractionation of about 40 major and trace elements te was performed on waters from boreal small rivers and their estuaries in the karelia region of north west russia around the vetreny belt mountain range and in paanajarvi national park northern karelia samples were filtered in the field using a progressively decreasing pore size 5 m 2 5 3 m 0 22 0 45 m 100 kda 10 and 1 kda by means of frontal filtration and ultrafiltration uf techniques and employing in situ dialysis with 10 and 1 kda membranes followed by icp ms analysis for most samples dialysis yields a systematically higher factor of 2 3 proportion of colloidal forms compared to uf nevertheless dialysis is able to provide a fast and artefact free in situ separation of colloidal and dissolved components similar to previous studies in european subarctic zones poor correlation of iron concentration with that of organic carbon oc in ultra filtrates and dialysates reflect the presence of two pools of colloids composed of organic rich and fe rich particles all major anions and silica are present as dissolved species or solutes passing through the 1 kda membrane size separation ultrafiltration experiments show the existence of larger or smaller pools of colloidal particles different for each of the considered elements the effect of rock lithology acidic versus basic on the colloidal speciation of te is seen solely in the increase of fe and some accompanying te concentrations in catchment areas dominated by basic rocks compared to granitic catchments neither the ultrafiltration pattern nor the relative proportions of colloidal versus truly dissolved te are affected by the lithology of the underlying rocks within 10 uncertainty the two colloidal 10 kda 0 22 m and 1 10 kda and the truly dissolved 1 kda pools show no difference in percentage of te distribution between two types of bedrock lithology the same conclusion is held for organic and fe rich waters in contrast landscape context analysis demonstrated slight dominance for most te affected by uf of large size colloids 10 kda 0 22 m in rivers and streams and small size colloids and truly dissolved fractions in swamp stagnant surface waters this supports the existence of two pathways of colloids formation during the plant litter degradation in wetland zones and at the redox front in river riparian zone

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

the potential of sedimentary foraminiferal rare earth element patterns to trace water masses in the past dissolved rare earth element ree concentration data from intermediate and deep seawater form an array characterized by higher middle ree enrichments mree mree in the north atlantic and a progressive increase in heavy to light ree ratios hree lree as water masses age the rees in foraminifera are fractionated towards higher mree mree and lower hree lree relative to seawater calculations based on a scavenging model show that the ree patterns in uncleaned core top foraminifera resemble those adsorbed onto calcite particulate organic material and hydrous ferric oxides but the full extent of the ree fractionation measured in foraminifera was not reproduced by the model however differences in the hree lree mree mree ratios and the cerium anomaly between ocean basins are preserved and are in agreement with the seawater ree distribution under oxic conditions the hree lree and mree mree compositions of uncleaned foraminifera at the sediment seawater boundary are preserved during burial but the cerium anomaly is sensitive to burial depth in suboxic sedimentary environments all uncleaned foraminiferal ree concentrations are elevated relative to core top values indicating addition of rees from pore waters the hree lree ratio is highest when sedimentation rates were greatest lippold et al 2009 and when high fe ca ratios in the uncleaned foraminifera indicate that fe was mobile in sediments that have not experienced suboxic conditions during burial uncleaned foraminifera preserve the seawater signal taken up at the sediment seawater interface and are therefore suggested to be a suitable archive of changes in the ree signal of past bottom waters this article is protected by copyright all rights reserved

rare earth elements distribution and geochemical behaviour in the volcanic groundwaters of mount vulture southern italy abstract the mount vulture basin which mainly consists of pyroclastic and subordinate lava flow layers is one of the most important aquifers for drinking water and irrigation supply in southern italy in this study we investigated the geochemical behaviour of the rare earth elements rees in the groundwater of this aquatic system assessing fractionation patterns and performing speciation calculations to elucidate the geochemical processes affecting the rees distribution the groundwater collected was separated into two subsets corresponding to recharge and discharge water overall the groundwater exhibited ree concentrations well below 1000 ng l and the average content measured in the discharge water is approximately three times higher than that of the recharge water in the recharge water the shale normalised patterns are characterised by a more negative average ce anomaly a more positive average eu anomaly and a larger average la yb paas the observed relationship between ce anomalies and dissolved oxygen do supports the idea that ce oxidative scavenging has a role in determining the size and shape of the ce anomaly further the less negative average size of the ce anomaly in the discharge zone also suggests ce desorption due to changes in redox conditions as for the eu anomalies the largest eu are associated with the recharge zone characterised by higher average eh and do values the volcanics in the mt vulture lithologies have post archean average shale paas normalised patterns showing positive eu anomalies due to feldspars occurrence this indicates that the eu of groundwater in the recharge zone is mostly produced by the dissolution of feldspars in the discharge zone most samples are in equilibrium with smectite and eu2 adsorption onto the clay phase surface or its inclusion in the mineral structure as exchangeable cations likely lead to the smaller average size of eu the possible occurrence of secondary minerals preferentially scavenging light rees may also explain the difference in the la yb paas index observed between the recharge and discharge zones speciation calculations indicate that dissolved rees consist mainly of carbonato complexes lnco3 whereas the percentage of dicarbonato complexes ln co3 2 increases in samples with circa neutral ph at acidic ph the ln3 species are numerous and in samples with large amounts of dissolved sulphate derived by feldspathoids dissolution from the discharge zone the percentage of lnso4 species is not negligible

paleodust deposition and peat accumulation rates bog size matters abstract we present a high resolution peat paleodust and accumulation rate record spanning the last 8300 years from draftinge mosse 400 ha southern sweden 57 06 27 6 n 13 42 54 1 e the record was analysed for peat accumulation rates par elemental concentrations mineralogy and plant macrofossil content five periods of increased mineral deposition were recorded the first event occurred between 6280 and 5570 cal bp during the fen to bog transition this is followed by four atmospheric mineral dust events de which were recorded in the ombrotrophic section of the sequence at cal bp 2200 1385 1150 830 590 and from 420 to the present statistical analysis and elemental ratios indicated that both the mineralogy and grain size shifted when the system transitioned from fen into bog showing that the governing transport process shifted with the peatland succession stages this highlights the importance of identifying peatland succession stages within peat paleodust studies following all four de increases in par were observed implying a coupling to dust deposition comparison of de and par with a paleodust record from store mosse a 20 times larger bog located ca 18 km away kylander et al 2016 showed that both par and dust deposition are largely represented by single core reconstructions indicating that they are driven by a common climate forcing mechanism however higher par and dust deposition rates were observed in the more moderately sized draftinge mosse suggesting that the size of the bog is important to consider in peat paleodust studies furthermore the smaller bog responded more rapidly to hydrological changes indicating that the size of the bog affects its buffering capacity authigenic carbonates observed here during episodes of rapid peat growth coincide with changes in ree ratios indicating that authigenic peat processes potentially cause ree fractionation

iron isotope fractionation in river colloidal matter temporal variations in the iron isotopic composition 56fe between 0 13 and 0 31 have been measured in the suspended fraction in a boreal river the major mechanism behind these variations is temporal mixing between two types of particles colloids fe oxyhydroxides and fe c colloids data in this study indicate that these two types of colloids have different fe isotope composition the fe c colloid has a negative 56fe value whereas the fe oxyhydroxide colloid is enriched in 56fe these two types of colloidal matter have different hydrogeochemical origin the fe c colloid reaches the river during storm events when the upper sections of the soil profile o and e horizons are flooded by a rising water table colloidal fe oxyhydroxides reach the river via inflow and subsequent oxidation of groundwater enriched in dissolved fe ii