partitioning of copper and zinc in the sediments and porewaters of a high elevation alkaline lake east central arizona u s a abstract in pacheta lake a high elevation alkaline lake proximal to the smelting region of southern arizona new mexico concentrations of transition metal ions in pore waters and co existing sediments were compared copper fe mn and zn have been partitioned among operationally defined sediment solid phases exchangeable sites organic complexes amorphous oxides crystalline oxides sulfides and residual silicates and their concentrations in interstitial waters were measured concentrations are reported as a function of depth in the sediment column the diagenetic environment is described and cycling mechanisms postulated for the above metals selective sequential extraction of metals from lake sediments showed different binding mechanisms for cu and zn the former most strongly associated with organic complexes and the latter with iron oxyhydroxides this difference has strong implications for selective metal remobilization under variable environmental conditions both naturally and anthropogenically induced copper and zinc in porewaters were estimated to diffuse to overlying waters at 12 8 and 21 9 g cm2 a respectively these fluxes are large enough to account for observed concentrations of cu and zn in overlying waters no sediment metal contamination was directly attributable to smelting activity however this study does document a flux from sediments which have accumulated cu and zn to overlying waters no longer receiving trace metal deposition from now inactive smelters

lead isotope analyses of gold silver ores from rosia montană romania a first step of a metal provenance study of roman mining activity in alburnus maior roman dacia the rosia montan ore deposit apuseni mountains romania is europe s largest au ag deposit it also corresponds to the roman alburnus maior mining site known by historians and archaeologists due to the discovery of dozens of roman wooden wax tablets during the underground works carried out during the 18th and 19th centuries the present geochemical research is based on a detailed archaeological and geological study of the roman mines at rosia montan making use of archaeologically and geologically documented ore samples the geochemical analyses allowed us to establish an accurate database for the ores exploited during roman times at rosia montan and probably before this approach represents a contribution towards improving the accuracy of metal provenance studies of gold silver ores during antiquity in romania and also at an european level because the studied ore samples represent remnants of the original ores used by the romans for the production of precious metals twenty nine ore samples and one litharge roll have been selected prepared and analysed by mc icp ms high resolution measurements a specific rosia montan pb isotope signature of gold silver ores extracted by the roman miners was obtained this signature is distinct when compared with other ore deposits from the apuseni mountains as well as within a broader region maramures ore district a litharge roll discovered in a roman inclined adit situated close to the surface which attests the presence of metallurgical workshops has also been analysed the different lead isotope values of the litharge roll and the rosia montan gold silver ores suggest that other ore sources from the south apuseni mountains or from elsewhere were also employed by the gold metallurgy developed at rosia montan during roman times

diversity of iron and silica precipitation by microbial mats in hydrothermal waters iceland implications for precambrian iron formations direct examination of microbial mats from icelandic hot springs with transmission electron microscopy and energy dispersive x ray spectroscopy revealed a consortium of bacterial cells in varying stages of mineralization differences in observed mineralogy largelyreflectdifferencesinthechemistryofthehydrothermalwaters silica richspheroids formedepicellularlyoncellwallsandsurroundingsheathsandcapsulesofmicroorganisms and insomecases intracellularlywhenpresumablythecell s hadlysed commonly these precipitateswereobservedcoalescingtoformamatrixofamorphoussilicathatcompletely encapsulated the cells and or replaced their cytoplasmic material however in other cells the precipitates were composed of amorphous granules made exclusively of iron and silica inapproximatelyequalproportions atonelocality thebacteriaformedseveralepicellular iron minerals ranging from iron mineralized capsules tofine grained spheroids of amorphous ferric hydroxide and acicular aggregates of goethite the complete encrustation of bacterial cells by silica iron or a combination of both may greatly enhance their preservation potential such that these mineralized microorganisms may conceivably represent future microfossils thus we may be witnessing contemporaneous biomineralization processes that are similar to those of the geologic past particularly with regard to the origin of some precambrian banded iron formations

ferricretes as a source of continental oolitic ironstones in northern sudan abstract in northern sudan lateritic ferricretes and oolitic ironstones occur the latter in both fluvial and marine sediments oolites and ferricretes display a close similarity such as a similar geochemical enrichment spectrum including v which is a key element to distinguish ferricretes from simple ferribands formed in hydromorphic soils in addition elevated al content of goethite ferricrete derived nuclei of ooids and the existence of continental oolites as link between weathering crusts and marine deposits point to a lateritic source of sedimentary iron oolites

satellite radar interferometry for monitoring ice sheet motion application to an antarctic ice stream satellite radar interferometry sri provides a sensitive means of monitoring the flow velocities and grounding line positions of ice streams which are indicators of response of the ice sheets to climatic change or internal instability the detection limit is about 1 5 millimeters for vertical motions and about 4 millimeters for horizontal motions in the radar beam direction the grounding line detected by tidal motions where the ice goes afloat can be mapped at a resolution of 0 5 kilometer the sri velocities and grounding line of the rutford ice stream antarctica agree fairly well with earlier ground based data the combined use of sri and other satellite methods is expected to provide data that will enhance the understanding of ice stream mechanics and help make possible the prediction of ice sheet behavior

redox zonation of elements at an oxic post oxic boundary in deep sea sediments abstract deep sea sediments generally provide limited evidence of redox control on the post depositional redistributions of elements this is because only a fraction of any element is reactive and observed elemental distributions are the result of a number of competing processes which are simultaneously active so that redox effects are not dominant a detailed investigation is reported of a core which is unusual in showing unequivocal evidence of direct redox control operating in a homogeneous environment that is relatively free from competing processes a progressive oxidation front has migrated slowly downwards into a uniform turbidite over a long period ca 250 ky the reactive fractions of several redox sensitive elements now show a remarkable degree of organisation around the redox boundary of this front with the different elements exhibiting individual responses solid phase enrichments are not coincident but are arranged in a clear succession of concentration peaks along the redox gradient from oxic to postoxic conditions the succession is mn i fe se and pt cu and pb v zn and sb and u the movement directions of most elements can be inferred from the peak shapes against the homogeneous turbidite background composition the system seems to have been essentially isolated within the sediment for most elements so that no loss or gain can be ascribed to redox processes exceptions are u and v which have been augmented by uptake from ocean bottom waters into the sediments by an efficient redox trap mechanism

trace metal deposition and mobility in the sediments of two lakes near sudbury ontario the accumulation and mobility of fe mn al cu ni and pb in the sediments of two lakes clearwater ph 4 5 and mcfarlane ph 7 5 near sudbury ontario have been investigated the al cu and ni concentrations are expectedly relatively high in the overlying waters of clearwater lake and much lower for al and cu in mcfarlane lake the low trace metal concentrations found in the anoxic porewaters of clearwater lake could be explained by a sharp increase in porewater ph concomitant with so42 reduction and h2s production within the first 1 2 cm of the sediments which has conceivably led to the precipitation of mineral phases such as al oh 3 nis and cus in both lakes fe concentrations in anoxic porewaters appear to be controlled by fes and or feco3 formation solubility calculations also indicate mnco3 precipitation in mcfarlane lake in clearwater lake however both porewater and total mn were relatively low a possible result of the continuous loss of mn ii through the acidic interface it is suggested that upwardly decreasing total mn profiles resulting from the removal of mn from the top sediment layers under acidic conditions may constitute a reliable symptom of recent lake acidification the downward diffusion of ai cu and ni from the overlying water to the sediments has been estimated from their concentration gradients at the interface and compared to their total accumulation rates in the sediments in both lakes the diffusion of al is negligible compared to its accumulation rate however diffusion accounts for 24 52 of the accumulation of cu in the sediments of clearwater lake but appears negligible in mcfarlane lake the downward diffusive flux of ni is important and may explain 76 161 of the estimated ni accumulation rate in clearwater lake and 59 in mcfarlane lake the porewater cu and ni profiles suggest that the subsurface sedimentary trace metal peaks observed in clearwater lake as in other acid lakes may not be caused by sediment leaching or by a recent reduction in sedimentation but may have a diagenetic origin instead diffusion to the sediments thus appears to be an important and previously overlooked trace metal deposition mechanism particularly in acid lakes

greenland ice sheet surface properties and ice dynamics from ers 1 sar imagery c band synthetic aperture radar sar imagery from the european space agency s ers 1 satellite reveals the basic zonation of the surface of the greenland ice sheet the zones have backscatter signatures related to the structure of the snowpack which varies with the balance of accumulation and melt at various elevations the boundaries of zones can be accurately located with the use of this high resolution imagery the images also reveal a large flow feature in northeast greenland that is similar to ice streams in antarctica and may play a major role in the discharge of ice from the ice sheet

redox front formation in an uplifting sedimentary rock sequence an analogue for redox controlling processes in the geosphere around deep geological repositories for radioactive waste subsurface redox fronts control the mobilization and fixation of many trace elements including potential pollutants such as certain radionuclides any safety assessment for a deep geological repository for radioactive wastes needs to take into account adequately the long term redox processes in the geosphere surrounding the repository to build confidence in understanding these processes a redox front in a reduced siliceous sedimentary rock distributed in an uplifting area in japan has been studied in detail geochemical analyses show increased concentrations of fe and trace elements including rare earth elements rees at the redox front even though concentrations of reduced rock matrix constituents show little change detailed sem observations revealed that fossilized microorganisms composed of amorphous granules made exclusively of fe and si occur in the rock s pore space microbial 16s rdna analysis suggests that there is presently a zonation of different bacterial groups within the redox band and bacterial zonation played an important role in the concentration of fe oxyhydroxides at the redox front these water rock microbe interactions can be considered analogous to the processes occurring in the redox fronts that would develop around geological repositories for radioactive waste once formed the fe oxyhydroxides within such a front would be preserved even after reducing conditions resume following repository closure

measurement of ice sheet topography using satellite radar interferometry detailed digital elevation models dems do not exist for much of the greenland and antarctic ice sheets radar altimetry is at present the primary in many cases the only source of topographic data over the ice sheets but the horizontal resolution of such data is coarse satellite radar interferometry uses the phase difference between pairs of synthetic aperture radar sar images to measure both ice sheet topography and surface displacement we have applied this technique using ers 1 sar data to make detailed i e 80 m horizontal resolution maps of surface topography in a 100 km by 300 km strip in west greenland extending northward from just above jakobshavns isbrae comparison with a 76 km long line of airborne laser altimeter data shows that we have achieved a relative accuracy of 2 5m along the profile these observations provide a detailed view of dynamically supported topography near the margin of an ice sheet in the final section we compare our estimate of topography with phase contours due to motion and confirm our earlier analysis concerning vertical ice sheet motion and complexity in ers 1 sar interferograms

hydrochemical baseline condition of groundwater at the mizunami underground research laboratory miu abstract hydrochemical conditions up to depths of 1000 m below ground level around the mizunami underground research laboratory were investigated to construct a baseline condition model describing the undisturbed hydrochemical environment prior to excavation of the underground facilities at mizunami gifu japan groundwater chemistry in this area was classified into a na ca hco 3 type of groundwater in the upper part of sedimentary rock sequence and a na ca cl type of groundwater in the deeper part of the sedimentary rock sequence and basement granite the residence time of the groundwaters was estimated from their 14 c contents to be approximately 9 3 ka in the middle part of the sedimentary rock and older than 50 ka in the deep part of the granite the evolution processes of these groundwaters were inferred to be water rock interactions such as weathering of plagioclase dissolution of marine sulphate sulphide minerals and carbonate minerals in the na ca hco 3 type of groundwater and mixing between low salinity water in the shallow part and higher salinity water in the deeper part of the granite in the na ca cl type of groundwater the source of salinity in the deeper part of the granite was possibly a palaeo hydrothermal water or a fossil seawater that recharged in the miocene subsequently being modified by long term water rock interaction the cl depth trend in granitic groundwater changes at a depth of 400 m below sea level the hydrogeological properties controlling the groundwater flow and or mixing processes such as advection and diffusion were inferred to be different at this depth in the granite this hydrochemical conceptual model is indispensable not only when constructing the numerical model for evaluating the hydrochemical disturbance during construction and operation of the miu facility but also when confirming a hydrogeological model

hydrothermal phase stabilization of 2 line ferrihydrite by bacteria poorly ordered 2 line ferrihydrite deposits from the caldera of axial volcano a site of hydrothermal vent activity along the juan de fuca ridge are characterized by an abundance of bacterial structures resembling gallionella ferruginea leptothrix ochracea and pv 1 filaments encrusted with nanoparticulate ferrihydrite ferrihydrite formed in the absence of bacteria can be metastable and will subsequently react to form more structurally ordered iron oxide phases such as hematite or goethite inspection of samples from 2 day 80 c aqueous heating experiments by electron microscopy and x ray diffraction revealed that a natural sample of bacteriogenic ferrihydrite from axial volcano did not undergo a phase transition whereas synthetic ferrihydrite absent of bacteria transformed to hematite after 2 days a series of bacterial ferrihydrite composites exhibited decreasing amounts of transformation to hematite with increased amounts of fe iii bound to bacteria complete inhibition was observed when 50 of the total fe was bound as ferric iron and 50 was present as ferrihydrite for the synthetic ferrihydrite samples containing bacteria the inhibition of ferrihydrite transformation is attributed to microbial surface functional groups i e carboxyl phosphoryl amine constraining the brownian motion of surface bound ferrihydrite nanoparticles thereby eliminating the aggregation and rotation of particles required for crystal growth the stabilization of ferrihydrite will prolong the longevity of a highly reactive mineral phase which may have implications for marine geochemistry and environmental remediation preservation of bacteria encrusted with transformation resistant ferrihydrite may enhance the potential usefulness of bacteriogenic ferrihydrite to harbour bacterial microfossils imparting these types of samples with potential use for paleontology and astrobiology

carbon 14 study of groundwater in the sedimentary rocks at the tono study site central japan isotopic investigations using 14c of groundwater were carried out to understand the hydraulic conditions in the sedimentary rocks at the tono study site central japan 14c activities of groundwater observed range from 2 to 32 modern carbon pmc measured 14c activities of groundwater are corrected by the isotopic mass balance model based on 14c activities 13c values concentrations of the dissolved inorganic carbon dic and 13c values of non active carbon dissolved into the groundwater from carbonate minerals and organics assuming that the groundwater reservoir is comparable to the piston flow situation the relative 14c ages of groundwaters were calculated from the corrected 14c activity the relative 14c age suggests that the groundwater infiltration from the upper part of the sedimentary rocks to the lower part takes several thousands of years or that the groundwater in the lower part of sedimentary rocks is derived from long distance flow from the surface through the unconformity between the sedimentary rocks and basement granite the flow rate calculated by relative 14c ages shows similar values to those estimated by computer simulation using hydraulic pressure and conductivity data hydraulic conditions at the tono study site inferred from 14c activity agree with those suggested from hydrogeological analyses isotopic approaches using 14c activity can be applied as geochemical evaluation for interpretations from the hydraulic study

atmospheric limitations to repeat track radar interferometry in its recent radar imaging mission the shuttle imaging radar satellite sir c devoted three days to repeat track interferometry we have analyzed the data from a test site in the mojave desert of california although good topography 10 m on 21 m postings was obtained most of the error was caused by turbulent water vapor in the lower atmosphere spatial structure of 6 km and all smaller sizes was observed the rms one way time delay was found to be 0 24 cm essentially identical results were obtained at two wavelengths 24 and 5 7 cm

mapping small elevation changes over large areas differential radar interferometry a technique that uses synthetic aperture radar sar images to measure very small 1 cm or less surface motions with good resolution 10 m over large swaths 50 km is presented along with experimental results the method could be used for accurate measurements of many geophysical phenomena including swelling and buckling in fault zones residual displacements from seismic events and prevolcanic swelling the method is based on sar interferometry where two images are made of a scene by simultaneously flying two physically separated antennas then the phases of corresponding pixels are differenced and altitude formation is deduced from some simple computation and image rectification it is also possible to use one antenna flown twice over the same scene then if the second flight exactly duplicates the track of the first an interesting possibility occurs there would be no phase changes between the images at all unless there was a physical change in the scene such as ground swelling that would alter the distance from some resolution element to the antenna since the phase changes all occur at the short carrier wavelength the basic limitation on sensitivity is only the phase noise in the system when the two imaging passes are made from flight tracks that are separated which is the case with the seasat images used here it is no longer possible to distinguish surface changes from the parallax caused by topography however with some additional computation a third image made at some other baseline may be used to remove the topography and leave only the surface changes this method was applied using seasat data to an imaging site in imperial valley california where motion effects were observed that were ascribed to the expansion of water absorbing clays phase change images of this area are shown along with associated ground truth about the presence of water problems with the technique are explored along with a discussion of future experimental possibilities on upcoming sar missions like earth observing system eos earth resources satellite ers 1 sir c and the venus imaging radar magellan

weathering rind formation in buried terrace cobbles during periods of up to 300ka abstract weathering rinds formed in mesozoic sandstone and basalt cobbles buried in terrace deposits for up to 300 ka have been investigated the aim was to determine the formation process and elemental mass balances during rind development the ages of terraces distributed in the western part of fukui prefecture central japan have been determined as 50 ka 120 ka and 300 ka based on a tephro stratigraphic method detailed investigations across the weathering rinds consisting of microscopic observations porosity measurements and mineralogical and geochemical analyses using x ray diffractometry xrd x ray fluorescence xrf secondary x ray analytical microscopy sxam scanning electron microanalyser sem and electron probe microanalysis epma have been carried out the results revealed that the fe concentrations in the weathering rind of a basalt cobble slightly decreased from the cobble s surface rim towards the unweathered core in contrast in a sandstone cobble formed under the same environmental conditions over the same period of time there is an fe rich layer at some distance below the cobble s surface elemental mass balances across the rinds were determined by using open system mass balance i j calculations and show that the fe was precipitated as fe oxyhydroxides in the basalt cobbles although fe was slightly removed from the rims in sandstone cobbles on the other hand fe migrated along a fe concentration gradient by diffusion and precipitated as fe oxyhydroxide minerals to form the weathering rinds presumably precipitation was due to the relatively higher ph conditions caused by mineral dissolution within the pores principally involving calcite but probably also silicates including feldspar the detailed characterization of the weathering rinds revealed the influence of lithology on the accumulation and dissolution of fe oxyhydroxides causing weathering rinds with different characteristics to develop in different kinds of buried cobbles under the same conditions relatively large climatic changes in the study area did not cause discernable variations in the mean formation rates of the studied rinds which were in the order of 10 8 m a for both basalt and sandstone cobbles these rates are 1 2 orders of magnitude slower than those reported for tropical areas elsewhere most probably due to the lower rainfall in the studied area

the development of fe nodules surrounding biological material mediated by microorganisms takashikozo is a phenomenon of quaternary sediments in japan they are cylindrical fe oxyhydroxide nodules that form as plaques round plant roots where fe is preferentially concentrated to develop a solid wall structural features suggest that after the roots have decayed the central space where the roots were situated acts as a flow path for oxidized water analysis of microbial 16s rdna extracted from the nodules identified iron oxidizing bacteria encrusted round the roots where they are the likely initiators of nodule formation direct microscopic observation revealed an accumulation of fe oxyhydroxides that fill the pore spaces and is also likely to be linked with the encrusting microbial colonies geological history and nanofossil evidence suggest that these fe nodules may have been buried at a depth of up to several tens of meters for at least 105 years in reducing quaternary sediments thus fe oxyhydroxide nodules that have formed in a geological environment at the interfaces between water and rock by microbial mediation can persist under reducing conditions if this is the case the phenomenon is significant as an analogue of post closure conditions in radioactive waste repositories since it could influence nuclide migration

w and m type tetrad effects in ree patterns for water rock systems in the tono uranium deposit central japan abstract abundances of rare earth elements plus y ree were determined for granitic rocks tertiary sedimentary rocks and related groundwater in the tono area central japan tetrad effects concave curves in ree patterns were found for these rocks and groundwater samples conjugate m and w types of tetrad effects were simultaneously observed in these specimens which constitute the water rock system the granitic rocks show the m type tetrad effects while the groundwater and the sedimentary rocks exhibit the w type tetrad effects non chondritic y ho ratios were found especially in the groundwater y ho ratios showed larger values than the chondritic value for the samples showing w type tetrad effects and vice versa these results suggest that 1 preference of the groundwater for a w type tetrad effect and larger y ho ratio than chondrite produces an m type tetrad effects and lower y ho ratios in the granitic rocks during weathering processes 2 the w type tetrad effect and larger y ho ratio for the sedimentary rocks is brought about by the fixation of groundwater ree onto the sedimentary rocks the variation of the tetrad effect and y ho ratio was confirmed by laboratory experiments on the leaching of ree from the granitic rocks the w type tetrad effect and large y ho ratio in the u mineralization zone in the sedimentary rocks were also found by sims analysis which is consistent with the w type tetrad effect and larger y ho ratio in the whole rock abundances of the sedimentary rocks disequilibrium of the u series 234 u 238 u analyzed by sims in the u mineralization zone suggests that the u bearing minerals were formed through precipitation from groundwater as it became reducing these results suggest that the ree in the sedimentary rocks were transported by the groundwater from the granitic rocks in the tono area based on this study it is implied that the degree of the tetrad effects and the variation of y ho ratio can be valuable tools to investigate the migration of ree during water rock interactions in natural systems

formation of fine grained metal and silicate precipitates on a bacterial surface bacillus subtilis abstract the ability of the gram positive bacterium b subtilis to bind and nucleate precipitates from silicate anions has been studied over 24 weeks in the presence of fe and a1 at concentrations close to those levels in soils and at slightly acid 5 5 and basic 8 0 ph in all cases formation of silicate crystallites quasi crystalline precipitates on the bacterial surfaces was observed bacterially mediated minerals were more diverse in composition and morphology less crystalline smaller and sometimes more abundant than those that were abiotically formed fe pretreatment of the bacterial cells enhanced the binding of silicate at ph 8 0 walls which were not pretreated with fe bound silicate more favourably at acid values when heavy metals pb cd zn cr ni cu were added to the mixture at ph 4 5 silicate retention was greatly favoured giving greater retention of either si or metals than was seen in abiotic controls experiments with only heavy metals showed a high affinity of the bacterial walls for the metals even at low temperatures 4 c it is postulated that a cationic bridging mechanism is involved in the binding of silicate anions by bacterial cell walls

redox front penetration in the fractured toki granite central japan an analogue for redox reactions and redox buffering in fractured crystalline host rocks for repositories of long lived radioactive waste abstract redox buffering is one important factor to be considered when assessing the barrier function of potential host rocks for a deep geological repository for long lived radioactive waste if such a repository is to be sited in fractured crystalline host rock it must be demonstrated that waste will be emplaced deeper than the maximum depth to which oxidizing waters can penetrate from the earth s surface via fractures during the assessment timeframe typically 1 ma an analogue for penetration of such oxidizing water occurs in the cretaceous toki granite of central japan here a deep redox front is developed along water conducting fractures at a depth of 210 m below the ground surface detailed petrographical studies and geochemical analyses were carried out on drill core specimens of this redox front the aim was to determine the buffering processes and behavior of major and minor elements including rare earth elements rees during redox front development the results are compared with analytical data from an oxidized zone found along shallow fractures up to 20 m from the surface in the same granitic rock in order to understand differences in elemental migration according to the depth below the ground surface of redox front formation geochemical analyses by xrf and icp ms of the oxidized zone at 210 m depth reveal clear changes in fe iii fe ii ratios and ca depletion across the front while fe concentrations vary little in contrast the redox front identified along shallow fractures shows strong enrichments of fe mn and trace elements in the oxidized zone compared with the fresh rock matrix the difference can be ascribed to the changing eh and ph of groundwater as it flows downwards in the granite due to reactions with rock forming minerals in particular feldspar dissolution these observations give important insights into the processes that control the rates of redox front penetration in fractured crystalline rock the findings of the study can be used to help build confidence among stakeholders that radioactive waste would be emplaced in such rocks at greater depth than that to which oxidizing water is likely to penetrate in future

estimation of ice sheet motion using satellite radar interferometry method and error analysis with application to humboldt glacier greenland satellite radar interferometry provides glaciologists with an important new tool for determining the motion and topography of large ice sheets we examine the sources of error in interferometrically derived ice motion measurements including those errors due to inaccurate estimates of the interferometric baseline several simulations are used to assess baseline accuracy in terms of tie point error and the number and distribution of tie points these results give insight into how best to select tie points and also demonstrate the level of accuracy that can be achieved examination of two representative cases likely to occur in mapping ice sheet motion leads to the conclusion that with adequate tie point information ice velocity can be measured accurately to within a few meters per year a method to correct horizontal velocity estimates for the effect of vertical displacement using surface slopes is also developed finally we estimate the single component velocity field for an area on humboldt glacier northern greenland using interferograms formed from ers i sar images we estimate that these velocity measurements are accurate to within 2 3 m year 1