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

rare earth element distribution in lake tyrrell groundwaters victoria australia abstract the rare earth element ree geochemistry of the saline to hypersaline acidic brines of lake tyrrell victoria australia were analyzed in order to determine the relative importance of concentration and modification processes in the lake system several types of brines were identified on the basis of different ree patterns and concentrations regional groundwater flowing into lake tyrrell yields the highest concentrations of ree while a transitional water group is identified on the basis of lower ree concentrations a third water group the reflux brine is characterized by extremely low ree concentrations the ree patterns suggest that ree are introduced to the lake tyrrell system by the regional groundwater which has concentrated ree from the aquifer material in its acidic waters eventually ree are removed from the evolving water mass as higher levels of ph are reached the data of the study strongly suggest that ree are scavenged from solution by fe oxyhydroxide phases which precipitate as the ph of the system rises water rock interactions probably control ph in the lake system and therefore ultimately control the concentration of ree in solution in this system our results are directly correlated with studies of hydrothermal vents and geothermal solutions which have shown the concentration of ree in solution to be dominantly controlled by ph

rare earth elements as geochemical tracers of regional groundwater mixing abstract the rare earth elements ree were analyzed in a groundwater system from south central nevada i e ash meadows national wildlife refuge the spring mountains pahranagat national wildlife refuge and the nevada test site in order to investigate their potential use as tracers of regional groundwater flow previous investigations using conservative tracers e g deuterium and uranium isotopes identified recharge in local mountains as the primary source 60 70 of total discharge for the springs in the regional discharge zone i e ash meadows with the remaining contribution being interbasin flow from the northeast initial mixing calculations for these groundwaters using shale normalized ree patterns agreed well with the previous studies however because the rees are not expected to behave conservatively in natural waters the effect of both solution complexation which acts to enhance the stability of the rees in solution as well as surface complexation responsible for the particle reactive behavior of the rees were examined in subsequent mixing calculations in order to assess the roles of solution and surface complexation relative partitioning coefficients were estimated for each ree in each groundwater by evaluating the ratio of the ionic strength corrected co 3 1 ree co 3 2 ree and co 3 2 f to the first hydrolysis binding constants for the rees the relative partitioning coefficients were then used to calculate ree patterns expected to develop and persist in solution as a consequence of solution and surface complexation the calculated ree values closely resembled the actual measured ree concentrations suggesting that the rees are in fact controlled by solution and surface complexation in these groundwaters the calculated ree concentrations were subsequently used to determine mixing ratios the results of which coincided with the initial calculations as well as the previous studies the results of this study suggest that solution complexation of the rees is sufficient to overcome to a certain degree the affinity of the rees to be adsorbed onto surface sites in the aquifers such that distinctive ree signatures develop and persist in solution in groundwaters from different aquifers the ability of solution complexation to overcome surface complexation is likely related to the formation of the negatively charged dicarbonato complex i e ln co 3 2 where ln is any ree which accounts for significant fractions of each ree in these groundwaters

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

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

isotopic and trace element constraints on the origin and evolution of saline groundwaters from central missouri na ca cl groundwaters with salinities of 1 to 30 discharge from natural springs and artesian wells in mississippian carbonates and ordovician sandstones and carbonates in central missouri carbonate saturation and quartz supersaturation are maintained throughout the salinity range major and trace element and isotopic variations in the waters are used to place constraints on models for rock water interaction and regional hydrology the groundwaters have d values that range from 108 to 45 and 18 o values that range from 14 7 to 6 5 smow these data lie approximately along the meteoric water line ranging from values similar to local recharge in missouri to significantly lower values that are similar to 18 o and d for meteoric recharge in high altitude and high latitude regions of north america the more saline samples have the lowest 18 o and d contents a trend that is opposite to that observed in most other studies of saline waters the h o isotopic correlation and the range in salinity and several major and trace element concentrations in central missouri groundwaters are readily explained by a saline dilute water mixing model 87sr 86sr ratios for the groundwaters range from 0 7155 to 0 7161 these values are significantly higher than previously published values for 1 estimates of 87 sr 86 sr in phanerozoic seawater 0 7068 0 7092 and 2 carbonates of the mississippian burlington keokuk fm 0 7075 0 7105 through which some of the waters migrate as they pass to the surface nd 0 values in the groundwaters range from 10 9 to 8 1 and 147 sm 144 nd ratios range from 0 108 to 0 128 these values are similar to or lower than previously published analyses of carbonates and other authigenic phases from the burlington keokuk fm mean nd 0 7 8 0 8 1 mean 147 sm 144 nd 0 141 the h o sr and nd isotopic data and the results of model calculations preclude 1 models involving the modification of ancient seawater for the origin of the saline waters and 2 extensive interaction between the groundwaters and their host carbonates the waters apparently acquired their 18 o and d values as meteoric recharge and their 87sr 86sr and rare earth element signatures from extraformational crustal sources high 87 sr 86 sr low nd 0 low 147sm 144nd and largely preserved these isotopic signatures during subsequent migration through the carbonates chemical exchange via rock water interaction is required for isotopic exchange to occur therefore the present state of chemical equilibrium between the groundwaters and carbonate aquifer minerals may serve to limit rock water interaction and hence preserve the extraformational isotopic signatures in the waters the integration of geochemical isotopic and hydrologic data on a local and regional scale suggests a history for the central missouri groundwaters involving 1 meteoric recharge in the front range of colorado 2 dissolution of permian halite in the subsurface of kansas 3 interaction with predominantly silicate mineral assemblages in paleozoic strata and possibly precambrian basement with aquisition of crustal sr and ree signatures 4 dilution and migration to shallow aquifer levels in central missouri and 5 mixing with local meteoric recharge through mississippian carbonates with no significant change of the isotopic signatures acquired in stage 3

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

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 geochemistry of rare earth elements in groundwater from the carnmenellis area southwest england shallow groundwater samples from the carnmenellis area of southwest england collected from wells boreholes springs adits and stream baseflow represent recently recharged waters of low salinity their major ion concentrations closely reflect the lithology of their host rocks which comprise the carnmenellis granite and devonian metasediments and metabasite of greenschist grade groundwaters from the granite are predominantly na cl or na ca cl type whilst those from the metasediment are na ca mg cl hco3 waters with a larger range of compositions the major ion compositions are predominantly a function of water rock interaction processes and the larger range of metasediment water compositions probably reflects the greater lithological variation the ph of groundwater samples circulating through granite is typically lower than that of groundwater in the metasediments the range being 4 3 to 7 2 median 5 7 and 4 7 to 8 0 median 6 6 respectively rare earth element ree concentrations of 0 45 m filtered groundwater samples have been determined by inductively coupled plasma mass spectrometry icp ms a large range of concentrations exists and many are below detection limits but levels reach up to 229 g 1 1 6 m total rees the rees are strongly controlled by ph with higher levels in groundwaters of ph 6 chondrite normalised profiles are light rare earth element lree enriched compared to heavy rare earths hrees with a common slight negative eu anomaly both features reflecting the compositions of their host rocks ree profiles therefore appear to be controlled by water rock interactions involving predominantly ree enriched minerals in the granite the rees are probably derived mainly from the accessory minerals monazite and apatite as well as the high ree framework minerals biotite and muscovite the source of rees in groundwater from the metasediments is more uncertain but probably includes clay minerals chlorite and carbonate ree compositions normalised to shale have flatter profiles although many are slightly convex with higher normalised sm eu and gd values a few metasediment derived waters with high total ree concentrations have lree enriched shale normalised patterns it is suggested that the bulk of the rees in these few samples is colloidal rather than totally dissolved groundwaters from the metasediments have a notable depletion in ce which is distinct from waters in the granite this depletion is problematic in that it is difficult to see how redox processes could be the dominant control since groundwaters from the metasediments are unlikely to be more oxidising than those from the granite likewise variations in ph fail to totally explain the distinctions in ce concentration and la ce ratios between the two water types it is therefore suggested that the ce contents are largely source related rather than process related the observed ree compositions of granite and metasedimentderived groundwaters from the carnmenellis area are so distinctive that the rees in general and ce in particular might be useful as future tracers in studies of water rock interaction and groundwater provenance

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

mineralogy and geochemistry of trace metals and ree in volcanic massive sulfide host rocks stream sediments stream waters and acid mine drainage from the lousal mine area iberian pyrite belt portugal abstract acid mine drainage represents a major source of water pollution in the lousal area the concentrations of trace metals and the rare earth elements ree in the host rocks stream sediment surface waters and acid mine drainage amd associated with abandoned mine adits and tailings impoundments were determined in order to fingerprint their sources and to understand their mobility and water rock interaction the results show that the fe so4 rich acid waters vary substantially in composition both spatially and seasonally these waters include very low ph mostly in the range 1 9 3 0 extreme so4 concentrations 4635 20 070 mg l 1 so 4 2 high metal contents fe al cu zn and mn and very high ree contents the trace metal concentrations decrease downstream from the discharge points either due to precipitation of neoformed phases or to dilution the north american shale composite nasc normalized patterns corresponding to sediment from one stream corona stream show a flat tendency or are slightly enriched in light ree lree the nasc normalized patterns corresponding to acidic mine waters show enrichment in the middle ree mree with respect to the lree and heavy ree hree moreover the ree concentrations in acidic mine waters are 2 or 3 orders of magnitude higher than those of the surface waters changes of ree concentrations and variation of eu anomaly show two spatially distinct patterns a pond and spring waters with higher ree concentrations ranging from 375 to 2870 g l 1 that records conspicuous negative eu anomaly and b seeps from tailings impoundments corresponding to lower ree concentrations than the first pattern ranging from 350 to 1139 g l 1 with typically negative eu anomaly the stream water samples collected from the impacted stream during the spring show a low ph 2 8 3 1 and contain high concentrations of fe and trace elements up to 61 mg l 1 also temporal variations of the ree concentrations were observed in the corona waters the results obtained show that the ree concentrations increase during the winter spring transition stream waters draining the lousal mine area show high ree concentrations reaching a maximum value of about 2846 g l 1 spring the mree concentrations are usually enriched with respect to both the lree and hree a decrease in ree concentrations and a ph increase from 3 to 6 was observed downstream of the confluence of a tributary stream the geochemistry of the waters strongly influenced the mineralogy and geochemistry of efflorescent sulfates precipitated on the banks of the streams polluted by amd the mineralogy is dominated by hexahydrite rozenite szomolnokite alunite gypsum halotrychite coquimbite copiapite and schwertmannite the ree concentrations determined in the efflorescent sulfates suggest a selective partitioning of the hree onto mg al oxyhydroxides

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

rare earth element resources in coal mine drainage and treatment precipitates in the appalachian basin usa abstract drainages from abandoned coal mines in the appalachian basin represent a potential source of rare earth elements and yttrium rey many of which are considered to be critical resources due to their use in electronics and batteries we report rey data from coal mine drainage cmd sites and precipitates from cmd treatment systems throughout pennsylvania most cmd discharges are enriched in total rare earth elements relative to concentrations expected in unaffected surface or ground waters generally by 1 4 orders of magnitude relative to the north american shale composite nasc which approximates the rock with which mine waters interact cmd waters generally show a pattern of enrichment in the middle ree including several identified as critical resources nd eu dy tb low ph discharges tend to have higher rey concentrations than circumneutral discharges and a precipitous drop in concentration around ph 6 6 suggests adsorption of rey in the mine water flow path at near neutral ph values treatment precipitates including fe oxy hydroxides ca mg lime slurries and si and al rich precipitates are enriched in rey relative to the average cmd discharge value by factors of 103 104 while the discharges and precipitates analyzed in this study did not overlap in space and time the overall rey pattern of the precipitates approximate those of the cmd but with a slight depletion in light rare earth elements the higher rey concentrations in precipitates from systems treating low ph discharges most likely reflects the generally higher rey concentrations in these discharges but this needs to be established through direct comparisons over multiple seasonal cycles we estimate that coal mine drainage outflows in the appalachian basin generate a total of about 538 metric tons of rey per year in a dissolved state with 83 of that from low ph

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

petrology mineralogy and geochemistry of submarine coals and petrified forest in the sozopol bay bulgaria abstract the mineralogy petrology and geochemistry of submarine coals and petrified tree trunks from the sozopol bay were investigated the coals are lignites of lower middle miocene age the petrified trunks are 40 cm up to 2 m high some of which are in growth position and others are fallen the main minerals in the coal are silicates of detrital origin clay minerals and authigenic pyrite authigenic sulfur and amber are present as well in the sozopol coals stored for 30 years a neoformed mineral assemblage comprising mainly of gypsum iron sulfates sulfates of varying fe na al k and mg content and halite has been observed the formation of the sulfates was induced by bacterial activity as well germanium li rb ti v mo cr mn co and ni are enriched in the coals as compared with the clarke values of the world brown coals in most of the samples studied the contents of ga b y w cu zn pb p and zr are elevated as well the element distribution is influenced by the lithotype composition most elements have a mixed mode of occurrence germanium v ti cr b na and ni and to a lesser extent sr and cu are organically associated while k li rb and fe have a distinct inorganic mode of occurrence molybdenum follows strictly the fe distribution it is suggested that the main sources of the trace elements were the volcanic rocks in the sediment source area from which the elements were leached in the peat bog

the development of acidic groundwaters in coal bearing strata part i rare earth element fingerprinting abstract this study examines the rare earth element ree pattern of acidic mine discharges in the durham basin ne england as a means of fingerprinting their sources and understanding the water rock interactions although whole rock compositions proved to be unhelpful mimicking acid mine water generation in a series of selective leachates of the coal and coal bearing strata gave ree patterns similar to those measured in the emergent waters ree ratios and anomalies were used as indicators of specific interactions in the development of acidic groundwater the implications of the findings for the classification and evolution of acid mine discharges are discussed

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

behavior of rare earth elements in groundwater during flow and mixing in fractured rock aquifers an example from the dandenong ranges southeast australia a previously defined flow system is used to investigate ree behavior at different stages along groundwater flow paths in fractured basalt and sedimentary aquifers results from this study indicate that ree concentrations and patterns predominantly reflect different types and rates of reactions taking place to those controlling major ion chemistry in areas where recharge is through sediments ree concentrations are high nd 8 62 31 61 ng l and localised processes such as source heterogeneity control ree patterns and concentrations increased concentrations of rees in these groundwaters where ph 6 1 is a result of early stage ree mobilisation in the flow system in contrast where groundwater recharges through basalt ree concentrations are low nd 2 40 4 75 ng l and ree concentrations are relatively constant along groundwater flow paths indicating steady state conditions groundwater from both the sediment and basalt aquifer systems flows into the local discharge area in contrast to tds contents and major ion ratios groundwater from the discharge area has ree concentrations nd 1 84 4 18 ng l and patterns that reflect a larger component of flow from the basalt aquifer lower ree concentrations of groundwater from the regional sedimentary aquifer may result from progressive ree sorption or co precipitation as indicated by an increase in y ho cl cn ratios and hree enrichment for groundwater with ph not vert similar 7 1 due to greater abundances of hree vs lree dicarbonato complexes

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

distribution of rare earth elements in crystalline bedrock groundwaters oslo and bergen regions norway abstract one hundred and fifty norwegian bedrock groundwater samples from bergen and from vestfold oslofjord have been analysed by icp ms techniques at two laboratories for a large suite of trace elements including rare earth elements rees and y the bedrock lithologies include granites dominated by the permian drammen granite and permian latites rhomb porphyries from oslofjord and caledonian precambrian granitic and gneissic lithologies in the bergen area the rees show good correlation with each other with the exception of eu rees generally show a weak negative correlation with ph ree concentrations are highest in waters in acidic lithologies and generally decrease with increasing atomic weight yttrium la ce and nd are the most abundant rees in the waters with median concentrations exceeding 0 1 g l on crustal paas normalised plots distinct geochemical signatures are observed for the different lithologies most groundwaters exhibit negative eu anomalies on such plots except for latitic waters from the oslo area which show a positive eu anomaly aquifer host rock normalised plots for groundwaters from vestfold indicate minor enrichment in heavier rees and depletion in ce during water rock interaction

late miocene southwestern chinese floristic diversity shaped by the southeastern uplift of the tibetan plateau in southwestern china and southeast asia modern geology and topography have been influenced strongly by the collision between the indian and eurasian plates the southeastern margin of the tibetan plateau is well known for its high biodiversity and diverse vegetation types while the present diversity is explained by the geological history of this region to date no study has looked at how past vegetation was shaped by geological and topographical history in this study we focus on three coeval late miocene leaf assemblages from yunnan lincang xiaolongtan and xianfeng the palaeoelevation of these three sites is reconstructed using enthalpy as a palaeoaltimeter enthalpy at the fossil site is reconstructed based on leaf physiognomy the difference between this enthalpy and enthalpy at sea level is used as a proxy for altitude the palaeoaltitudes are resolved as 214 901 m asl for lincang 530 901 m asl for xiaolongtan and 1936 901 m asl for xianfeng the floristic components of these floras are analysed for their geographical elements there is a gradient in the percentage of tropical genera between the three floras from lincang at the lowest elevation to xianfeng at the highest level for lincang this percentage exceeds the threshold used to define present day tropical regions our results demonstrate that there as already a floristic differentiation in yunnan during the late miocene floras with tropical affinities were at low altitude whereas floras with temperate affinities were at high altitude with the later uplift of southern yunnan floras with tropical affinities retreated to the south where they are still present the uplift framework reconstructed in this paper gives a tectonic context for further studies on the impact of uplift on biodiversity c 2014 elsevier b v all rights reserved

comparing flux averaged and resident concentration in a fractured bedrock using ground penetrating radar this is the published version copyright 2010 by the american geophysical union all rights reserved

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 old biogenic apatites abstract the ree distributions in individual upper devonian conodonts have been measured by ion probe the patterns of all analyzed conodonts are enriched in middle ree eu gd and have a weak or no ce anomaly concentrations and la yb or la sm ratios vary very little within or among individuals from the same zone which suggests that uptake of labile ree from sediments was essentially quantitative therefore the ree signature of the primary carriers probably organic and oxyhydroxides particulates from marine suspensions was efficiently transferred to biogenic apatites and survived late diagenetic processes ree patterns of conodonts do not resemble those of present day seawater and post cretaceous biogenic phosphates which are typically depleted in nd and sm with a negative ce anomaly since ree distributions in the modern water column mimic those of nutrients we assume that in pre cretaceous seawater they were not controlled by surface biological activity we assume instead that ree in pre cretaceous seawater can be explained by mechanism of desorption adsorption on particle surfaces progressive extraction of lree from river water by oxyhydroxides leads to precipitates enriched in middle ree a simple quantitative model was calculated in order to illustrate the proposed mechanism

rare earth element fractionation and concentration variations along a groundwater flow path within a shallow basin fill aquifer southern nevada usa abstract rare earth element ree concentrations were measured in 5 well water samples and 3 springs located along a groundwater flow path in a shallow tuffaceous alluvial aquifer from southern nevada usa the ree concentrations in these groundwaters decrease in the direction of groundwater flow a previous investigation demonstrated that ree solid liquid phase partitioning coefficients i e kd s for groundwaters from tuffaceous alluvial aquifers in southern nevada are relatively high mean kd 102 6 our groundwater ree data in conjunction with these kd s support strong sorption of aqueous rees to aquifer surface sites as the primary removal mechanism of rees from these groundwaters in addition relatively high aqueous ree concentrations occur at distinct locations along the groundwater flow path the elevated ree concentrations are explained by addition of deeper groundwaters influx of geothermal waters from a hot spring system differences in solution complexation and or mixtures of regional and local recharge sources solution complexation modelling of rees in the groundwaters indicate that carbonate complexes account for more than 99 of each rees in solution moreover groundwater yb nd ratios a measure of ree fractionation are associated with alkalinity hco3 co32 r 0 71 the data and speciation model results indicate that ree fractionation i e the observed heavy ree hree enrichments compared to rock sources is controlled by formation of progressively stronger carbonate complexes in solution with increasing atomic number which inhibits hree sorption compared to light rees lree and a greater affinity for the lrees to sorb to surface sites in the local tuffaceous alluvial aquifers compared to the hrees

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

rare earth element geochemistry of sulphide weathering in the sao domingos mine area iberian pyrite belt a proxy for fluid rock interaction and ancient mining pollution gossan disseminated orebody waste other mining wastes minesoils and acid mine drainage amd in the abandoned sao domingos mine area iberian pyrite belt ipb have been analyzed for rare earth elements ree the main aim is to understand ree mobility during sulphide weathering so that the lanthanide series can be used both as a record of the water rock interaction and as a tool for identifying impacts of amd on natural ecosystems north american shale composite nasc normalized ree patterns corresponding to the disseminated orebody waste are relatively flat emree 0 01 0 12 however nasc normalized ree distributions in amd from sulphide oxidation tend to be enriched in middle ree mree compared to light ree lree and heavy ree hree as a consequence gossan resulting from supergene alteration of massive sulphide presents an evident nasc normalized mree depleted signature thus the overall water sulphide interaction defines complementary convex emree 0 72 0 25 and concave emree 0 31 0 12 nasc normalized patterns in draining waters and oxidation products respectively solutions extracted from minesoils have also nasc normalized patterns with mree enriched signature emree 0 62 0 22 similar to amd the emree parameter is proposed to measure the curvature in the mree segment and its size is quantified as the normalized maximum vertical difference between the polynomial curve fitting of the mree region and its theoretical y axis position in the absence of enrichment or depletion emree 0 for mree enriched signatures 0 for mree depleted signatures and 0 for horizontal patterns the sao domingos stream although it has been highly affected by amd flows into the guadiana river that has an estuarine system where pollution is considerably attenuated due to the mixing according to the metal geoaccumulation indexes currently used in the literature however sediments of this estuary were also analyzed and reflect mree enriched signatures emree 0 25 0 03 which demonstrate that this apparently non polluted estuarine system is being certainly affected by historical mining activities from the ipb the emree index is more sensitive to recognize curved mree signatures than other normalized ratios such as la gd nasc validating the use of ree patterns as a proxy for environmental pollution by amd

geochemical processes affecting the acidic groundwaters of lake gilmore yilgarn block western australia a preliminary study using neodymium samarium and dysprosium neodymium samarium and dysprosium concentrations were determined in groundwaters along a transect of lake gilmore sediments from the shoreline toward the playa center with the future intention of employing the whole suite of rare earth elements ree two different water bodies were identified in the groundwater playa system based on the neodymium samarium and dysprosium concentrations and associated ph and salinity values shallow groundwaters that discharge along the playa margins had the highest concentrations of these elements and the lowest ph and salinity a more saline entrained brine was identified toward the middle of the playa with higher ph values and the lowest observed concentrations of neodymium samarium and dysprosium groundwaters with transitional neodymium samarium and dysprosium values ph and salinity were also recorded along the transect the data suggest that the acidic shallow groundwaters remove ree from the surrounding granitic rocks of the yilgarn block and introduce them into the playa where they are removed from solution as the ph of the system increases evaporative concentration does not appear to have a significant effect on the ree concentrations in the lake gilmore system other factors such as increasing ph and scavenging of ree by iron oxyhydroxides which precipitate as ph rises appear to exert more control on ree concentrations in the groundwaters by removing them from solution

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

mobility and speciation of rare earth elements in acid minesoils and geochemical implications for river waters in the southwestern iberian margin abstract this paper discusses the abundance fractionation and chemical speciation of the rare earth elements ree released during two contrasting water soil interactions using acid sulfate and circumneutral soil samples from an abandoned mine land watershed in sw spain our simulative experiment shows that the ree mobility is strongly dependent on the soil solution acidity the acid solution extracts ph 3 1 3 7 extracted from the minesoils display overall ree concentrations much higher up to three orders of magnitude than those of the near neutral soil extracts the middle ree mree were preferentially removed when compared to light ree lan smn 0 07 and heavy ree gdn ybn 2 49 the origin of this mree enriched signature is attributed to dissolution and or solid liquid exchange reactions involving iron oxy hydroxides particles and surface coatings the ree were found to behave conservatively under the strong acid conditions of the soil solutions with sulfate complexes mainly lnso4 being the largely dominant aqueous species 75 80 despite the competitive effects of aluminium free metal ions ln3 accounted for most other species in solution 12 16 all other ligands analysed phosphate nitrate chloride fluoride and bicarbonate were not predicted to be significant complexers of ree according to speciation calculations the results of this study have implications for the ree geochemistry of the rivers draining the mine sites of the iberian pyrite belt the acid sulfate soils represent a major readily leachable mree reservoir for the tinto odiel fluvial system which reflect the geochemical signature of the soil water interaction in the mine lands watersheds