model based analysis of δ34s signatures to trace sedimentary pyrite oxidation during managed aquifer recharge in a heterogeneous aquifer the oxidation of pyrite is often one of the main drivers affecting groundwater quality during managed aquifer recharge in deep aquifers data and techniques that allow detailed identification and quantification of pyrite oxidation are therefore crucial for assessing and predicting the adverse water quality changes that may be associated with this process in this study we explore the benefits of combining stable sulphur isotope analysis with reactive transport modelling to improve the identification and characterisation of pyrite oxidation during an aquifer storage and recovery experiment in a chemically and physically heterogeneous aquifer we characterise the stable sulphur isotope signal 34s in both the ambient groundwater and the injectant as well as its spatial distribution within the sedimentary sulphur species the identified stable sulphur isotope signal for pyrite was found to vary between 32 and 34 while the signal of the injectant ranged between 9 06 and 14 45 during the injection phase of the experiment both isotope and hydrochemical data together suggest a substantial contribution of pyrite oxidation to the observed temporally variable 34s signals the variability of the 34s signal in pyrite and the injectant were both found to complicate the analysis of the stable isotope data however the incorporation of the data into a numerical modelling approach allowed to successfully employ the 34s signatures as a valuable additional constraint for identifying and quantifying the contribution of pyrite oxidation to the redox transformations that occur in response to the injection of oxygenated water

evidence for denitrification regulated by pyrite oxidation in a heterogeneous porous groundwater system abstract denitrification is an important natural attenuation process that has been observed in many fissured and porous aquifers however an important factor limiting denitrification in aquatic systems is the microbial availability of electron donors pyrite as the most abundant sulfide mineral in nature represents one of the potential electron sources for denitrifiers to reduce nitrate but the reaction mechanisms coupling denitrification processes to pyrite oxidation are still questionable we utilized hydrochemical data and stable isotopes of nitrate and sulfate in groundwater isotope ratios of sulfur compounds in aquifer sediments and tritium based groundwater dating for assessing denitrification processes in a pyrite bearing porous groundwater system the oxic part of the aquifer with mean water transit times of approximately 60 years was characterized by nitrate concentrations of around 15 mg l and 15 n values were similar to those typical for nitrification in contrast in the anoxic part with mean water transit times of up to 100 years low nitrate concentrations accompanied by elevated 15 n values were observed furthermore isotope data of groundwater sulfate and sulfur compounds in the aquifer sediment suggest that pyrite oxidation is the dominant source of sulfate in the aquifer the trend of increasing 15 n values and decreasing nitrate concentrations in concert with depleted 34 s values of groundwater sulfate similar to 34 s values of pyrite fes 2 suggests that denitrification is coupled to pyrite oxidation particularly when water mean transit time is elevated

lava flow identification and aging by means of lidar intensity mount etna case 1 an application of light detection and ranging lidar intensity for the identification and mapping of different lava flows from the mount etna italy active volcano is described in september 2004 an airborne lidar survey was flown over summit sectors of mount etna the information derived from lidar intensity values was used to compare the lava flows with respect to their age of emplacement analyzed lava flows vary in age between those dating prior to a d 1610 and those active during the survey 2004 2005 eruptions the target emitter distance as well as surface roughness and texture at the lidar footprint scale is the main parameter controlling the intensity response of lava flows variations in the roughness and texture of surfaces at a meter scale result from two main processes initial lava cooling and subsequent surface weathering both lead to variations in the original surface roughness of the flow in summary 1 initially from the time of emplacement the lidar intensity of lava flow surfaces decreases and 2 about 6 years after emplacement the lidar intensity of lava surfaces starts to increase with the age of flows lidar capability in terms of geometric accuracy of 1 m in plan position and less than 1 m in elevation and spectral lidar intensity depends on surface reflection at 1 064 m information can thus be effectively used to map lava flows and to define a relative chronology of lava emplacement

mixing of siliciclastic and carbonate sediments in shallow shelf environments the inhibiting effect that siliciclastic material has on carbonate secreting organisms has lead to the generalization that sediments composed of mixtures of carbonate and siliciclastic material should rarely form however many modern and ancient shelf deposits contain a spectrum of sediments that are of mixed composition the processes responsible for this mixing can be grouped into four categories 1 punctuated mixing where sporadic storms and other extreme periodic events transfer sediments from one depositional environment to another 2 facies mixing where sediments are mixed along the diffuse boundaries between contrasting facies 3 in situ mixing where the carbonate fraction consists of the autochthonous or parautochthonous death assemblages of calcareous organisms that accumulated on or within siliciclastic substrates and 4 source mixing where admixtures are formed by the uplift and erosion of nearby carbonate source terranes the allochemical constituents of mixed sediments are both coralgal and foram mollusc in composition the foram mollusc assemblage is the most common because of the effects of increased turbidity unstable substrates and the clogging of filter feeding mechanisms associated with a siliciclastic influx

submarine landslides on the great barrier reef shelf edge and upper slope a mechanism for generating tsunamis on the north east australian coast shallow 200 m submarine landslides influence margin evolution and can produce devastating tsunamis yet little is known about these processes on mixed siliciclastic carbonate margins we have discovered seven landslides along the shelf edge and upper slope of the central great barrier reef gbr australia the largest shelf edge landslide is investigated in detail and represents a collapse of a 7 km long section of the shelf edge at 90 m water depth with coarse debris deposited up to 5 5 km away on the upper slope down to 250 m the precise timing and triggering mechanisms are uncertain but available chronologic and seismic stratigraphic evidence suggest this event occurred during the last deglacial sea level rise between 20 and 14 ka regional bathymetric data confirms that these shelf edge and upper slope slides are restricted to the central gbr between latitude 18 and 19 s suggesting a spatial relationship between the extensive burdekin paleo fluvial delta system and shallow landslide activity this study highlights an important local mechanism for the generation of tsunamis on this margin type and numerical simulations under present conditions confirm a 2 to 3 m tsunami wave could be produced locally however we consider that the risk of such slides and their resulting tsunamis to the modern coastline is negligible due to their relatively small size and the capacity of the gbr to dissipate the wave energy

geochemical reconstruction of the provenance weathering and deposition of detrital dominated sediments in the perth basin the cretaceous leederville formation south west australia article i nfo the deep n10 km permian to present day perth basin in southwest western australia is composed of sedimentary successions of continental to shallow marine origin this study examines the compositional variation weathering and provenance of the early cretaceous leederville formation within the perth basin over 200 sediment samples were retrieved from two deep boreholes of 350 to 530 m in depth encompassing the leederville formation and analysed for major and trace element geochemistry and mineralogy the leederville formation is composed of subarkosic sands predominantly composed of quartz 64 and k feldspars 27 silts and clays composed of kaolinite 24 54 k feldspars 20 29 and quartz 18 40 with their compositional variation reflecting weathering hydraulic sorting during transport mostly subaqueous deposition and subsequent diagenesis most trace elements are associated with fine grained lithologies due to their occurrence within clays sulphide or zircon major and trace element geochemistry suggests a typical passive margin origin with minimal intrabasinal sediment recycling the regionally extensive yilgarn craton appears to be the main sediment source for the leederville formation within the study area

extreme sulphur isotope fractionation in the deep cretaceous biosphere abstract isotopically light sulphur in sedimentary pyrite was generally predominant during the cretaceous as a consequence of volcanic and hydrothermal activity and bacterial sulphate reduction bsr however we report super high sulphur isotopic compositions of sedimentary pyrite 34 s 89 3 from late mid cretaceous sediments from the central apennines italy these exceptionally high 34 s values are not consistent with current models for interpreting the geological record for sulphur isotopes because these cannot explain the extreme isotopic fractionation observed in our study precise details of the mechanism for producing pyrite so highly enriched in 34 s remain elusive but the large variation in 34 s values 70 within the analysed samples and the considerable micro scale variations in 34 s up to 50 even within a single nodule indicate a complex mechanism of sulphate reduction and pyrite precipitation this includes early removal of isotopically light h 2 s by pyrite precipitation in the water column diffusion and advection of h 2 s and so 4 2 and finally bsr similar but less severe conditions occur in the black sea and in deep ocean sediments these new findings provide new insights for the interpretation of the palaeoceanographic conditions that prevailed during the mesozoic

mid cenozoic fluvio deltaic to marine environments of the salin sub basin central myanmar abstract the salin sub basin is one of several basins within the wide elongate north south trending central basin in myanmar a field based campaign targeted the deposits of the reportedly oligocene shwezetaw padaung and okhmintaung formations which previously have been described only from spatially restricted and incomplete core records and limited field studies a minimum of 2 5 km thickness of these formations in the sub basin records a high sedimentation rate and long term subsidence which broadly kept pace with sediment input facies analysis based on sedimentary logs and panel diagram interpretation interprets these formations as deposits of large scale broadly southward flowing fluvial systems that interacted with deltaic and shallow marine environments in the southwestern parts of the basin a switch from south to southwest flowing rivers midway down the basin suggests these systems fed sediment to offshore basins in the west the overall environment was somewhat similar to the modern day irrawaddy river and delta despite the recorded high sedimentation rates and the coeval subsidence the depositional environment does not show much variation the main control is overall relative sea level rise associated with a northeastward marine transgression into the basin with contemporaneous smaller scale cycles of sea level rise and fall in terms of basin development this considerable thickness of clastic sediment indicates significant emergent sources palaeoenvironment reconstructions suggest that the south flowing fluvial systems sourced sediment from the northern margin of the basin but there were also some channels joining the main channel from the western margin of the basin and fewer channels from the northeast

development of equatorial delta front patch reefs during the neogene borneo abstract miocene patch reefs formed in turbid waters associated with high siliciclastic input at the seaward margin of the equatorial mahakam delta in eastern borneo se asia patch reefs were initiated on unstable substrates on localized low relief bathymetric highs associated with delta front channels or distributary mouthbars in the process of abandonment patch reefs developed only in shallow waters formed low relief buildups lacked rigid frameworks and had gently sloping margins although the biodiversity of the patch reefs may be comparable with that of clear water systems all the organisms present were adapted to turbid water areas associated with siliciclastic and sometimes nutrient influx the patch reefs were transient features and their demise was influenced by increased siliciclastic and nutrient input perhaps at times associated with deepening carbonate production and bioherm or patch reef development can occur in turbid water delta front areas as localized or more regionally extensive units during any phases of eustatic sea level however development and preservation of turbid water carbonates is most likely during relative transgression or perhaps late lowstand periods this is in contrast with common highstand carbonates from clear water shelves where nearly pure carbonates interdigitate with siliciclastics it is the interplay between factors such as tectonics eustasy delta lobe switching shelf currents and amount and size fraction of siliciclastic influx that ultimately controlled carbonate development and preservation

the modern mixed carbonate siliciclastic abrolhos shelf implications for a mixed depositional model abstract high resolution seismic facies analysis and stratigraphy of a mixed carbonate siliciclastic shelf yields insights into sedimentation controlled by interactions among carbonate production siliciclastic sediment supply and changes in relative sea level high resolution seismic core and surface samples collected along the northern area of the abrolhos shelf brazil including the inner middle and outer shelf constrain the genesis of the shelf two sets of seismic sequences were identified a pleistocene sequence and pleistocene holocene sequence a subaerial unconformity from subaerial exposure during the last glacial maximum separates the two sequences the upper seismic sequence the focus of this study comprises retrograding aggrading transgressive and aggrading prograding regressive seismic geometries carbonate sedimentation predominated within the last postglacial transgressive phase the subsequent regressive phase was dominated by nearshore siliciclastic sedimentation at shallow depths up to 12 m below 12 m depth a transition occurs to mixed siliciclastic carbonate facies and ultimately carbonate sedimentation farther offshore seismic data indicate that holocene nearshore coral reef growth was influenced by the positive antecedent relief of a pleistocene reef platform and terrigenous sedimentation although siliciclastic carbonate mixed sedimentation has been reported in other successions during periods of regression siliciclastic sedimentation in northern abrolhos shelf is limited to nearshore settings rather than bypassing the shelf

sulfide oxidation and sulfate reduction in a shallow groundwater system oderbruch aquifer germany abstract detailed groundwater monitoring was carried out over a period of two years in an anoxic river recharged aquifer of the oderbruch polder north eastern germany isotope data from wells located in a 5 km transect along the flow direction was used to determine sources and sinks of so 4 2 in the aquifer the so 4 2 originates from river water infiltration and from oxidative dissolution of fes 2 within the alluvial loam covering the aquifer sands a change of confined hydraulic conditions near the river to unconfined conditions in the central polder effects the hydrochemistry of the aquifer the confined areas are dominated by sulfate reduction increasing 34 s so 4 values suggest continuous but slow t 1 2 50 years sulfate reduction from the beginning of inflow onwards with 34 s so 4 values ranging from 1 8 to 44 7 versus cdt and an enrichment factor of 33 a zone with a strong sulfate depletion 34 s so 4 of up to 85 7 exists in a shallow microenvironment rich in solid phase organic carbon between river and levee in the unconfined areas of the central polder a so 4 2 plume with concentrations exceeding the original river water content indicates fes 2 oxidation by o 2 and or no 3 within the alluvial loam the lowered 34 s so 4 value reflects the input of the isotopically lighter so 4 2 from the sulfide

heat and mass transport during a groundwater replenishment trial in a highly heterogeneous aquifer changes in subsurface temperature distribution resulting from the injection of fluids into aquifers may impact physiochemical and microbial processes as well as basin resource management strategies we have completed a 2 year field trial in a hydrogeologically and geochemically heterogeneous aquifer below perth western australia in which highly treated wastewater was injected for large scale groundwater replenishment during the trial chloride and temperature data were collected from conventional monitoring wells and by time lapse temperature logging we used a joint inversion of these solute tracer and temperature data to parameterize a numerical flow and multispecies transport model and to analyze the solute and heat propagation characteristics that prevailed during the trial the simulation results illustrate that while solute transport is largely confined to the most permeable lithological units heat transport was also affected by heat exchange with lithological units that have a much lower hydraulic conductivity heat transfer by heat conduction was found to significantly influence the complex temporal and spatial temperature distribution especially with growing radial distance and in aquifer sequences with a heterogeneous hydraulic conductivity distribution we attempted to estimate spatially varying thermal transport parameters during the data inversion to illustrate the anticipated correlations of these parameters with lithological heterogeneities but estimates could not be uniquely determined on the basis of the collected data

hydrochemistry mineralogy and sulfur isotope geochemistry of acid mine drainage at the mt morgan mine environment queensland australia mineralogical hydrochemical and s isotope data were used to constrain hydrogeochemical processes that produce acid mine drainage from sulfidic waste at the historic mount morgan au cu mine and the factors controlling the concentration of so4 and environmentally hazardous metals in the nearby dee river in queensland australia some highly contaminated acid waters with metal contents up to hundreds of orders of magnitude greater than the australia new zealand environmental standards by pass the water management system at the site and drain into the adjacent dee river mine drainage precipitates at mt morgan were classified into 4 major groups and were identified as hydrous sulfates and hydroxides of fe and al with various contents of other metals these minerals contain adsorbed or mineralogically bound metals that are released into the water system after rainfall events sulfate in open pit water and collection sumps generally has a narrow range of s isotope compositions 34s 1 8 3 7 that is comparable to the orebody sulfides and makes s isotopes useful for tracing so4 back to its source the higher 34s values for no 2 mill diesel sump may be attributed to a difference in the source dissolved so4 in the river above the mine influence and 20 km downstream show distinctive heavier isotope compositions 34s 5 4 6 8 the dee river downstream of the mine is enriched in 34s 34s 2 8 5 4 compared with mine drainage possibly as a result of bacterial so4 reduction in the weir pools and in the water bodies within the river channel the so4 and metals attenuate downstream by a combination of dilution with the receiving waters so4 reduction and the precipitation of fe and al sulfates and hydroxides it is suggested here that in subtropical queensland with distinct wet and dry seasons temporary reducing environments in the river play an important role in s isotope systematics

tectonically controlled sedimentation impact on sediment supply and basin evolution of the kashafrud formation middle jurassic kopeh dagh basin northeast iran the kashafrud formation was deposited in the extensional kopeh dagh basin during the late bajocian to bathonian middle jurassic and is potentially the most important siliciclastic unit from ne iran for petroleum geology this extensional setting allowed the accumulation of about 1 700 m of siliciclastic sediments during a limited period of time upper bajocian bathonian here we present a detailed facies analysis combined with magnetic susceptibility ms results focusing on the exceptional record of the pol e gazi section in the southeastern part of the basin ms is classically interpreted as related to the amount of detrital input the amount of these detrital inputs and then the ms being classically influenced by sea level changes climate changes and tectonic activity facies analysis reveals that the studied rocks were deposited in shallow marine slope to pro delta settings a major transgressive regressive cycle is recorded in this formation including fluvial dominated delta to turbiditic pro delta settings transgressive phase followed by siliciclastic to mixed siliciclastic and carbonate shoreface rocks regressive phase during the transgressive phase hyperpycnal currents were feeding the basin these hyperpycnal currents are interpreted as related to important tectonic variations in relation to significant uplift of the hinterland during opening of the basin this tectonic activity was responsible for stronger erosion providing a higher amount of siliciclastic input into the basin leading to a high ms signal during the regressive phase the tectonic activity strongly decreased furthermore the depositional setting changed to a wave to tide dominated mixed carbonate siliciclastic setting because of the absence of strong tectonic variations bulk ms was controlled by other factors such as sea level and climatic changes fluctuations in carbonate production possibly related to sea level variations influenced the ms of the siliciclastic carbonate cycles carbonate intervals are characterized by a strong decrease of ms values indicates a gradual reduction of detrital influx therefore the intensity of tectonic movement is thought to be the dominant factor in controlling sediment supply changes in accommodation space and modes of deposition throughout the middle jurassic sedimentary succession in the pol e gazi section and possibly in the kopeh dagh basin in general

modeling biogeochemical processes and isotope fractionation of enhanced in situ biodenitrification in a fractured aquifer enhanced in situ biodenitrification eib is a feasible technology to clean nitrate polluted groundwater and reach drinking water standards aimed at enabling a better monitoring and management of the technology at the field scale we developed a two dimensional reactive transport model rtm of a cross section 26 5 4 m of a fractured aquifer composed of marls involving both biogeochemical processes and associated isotope fractionation the rtm was based on the upscaling of a previously developed batch scale model and on a flow model that was constructed and calibrated on in situ pumping and tracer tests the rtm was validated using the experimental data provided by vidal gavilan et al 2013 the model considers several processes including i exogenous and endogenous microbial nitrate and sulfate respiration coupled to ethanol oxidation and linked to microbial growth and decay and ii geochemical interactions dissolution precipitation of calcite and iii isotopic fractionation of the reaction network 15n no3 18o no3 13c dic 13c ethanol 13c biomass and 13c calcite most of the calibrated microbiological parameter values at field scale did not change more than one order of magnitude from those obtained at batch scale which indicates that parameters determined at the batch scale can be used as initial estimates to reproduce field observations provided that groundwater flow is well known in contrast the calcite precipitation rate constant increased significantly fifty times with respect to batch scale the incorporation of isotope fractionation into the model allowed to confirm the overall consistency of the model and to test the practical usefulness of assessing the efficiency of eib through the rayleigh equation approach the large underestimation of the rayleigh equation of the extent of eib from 10 to 50 was caused by the high value of hydrodynamic dispersion observed in this fractured aquifer together with the high reaction rates

geochemical controls on sediment reactivity and buffering processes in a heterogeneous aquifer the injection and recovery of oxic water into deep anoxic aquifers may help to alleviate short and longterm imbalance between freshwater supply and demand the extent and structure of physical and geochemical heterogeneity of the aquifer will impact the water quality evolution during injection storage and recovery water sediment interactions within the most permeable parts of the aquifer where the bulk of the injectant will penetrate may dominate however water quality may also be impacted by interactions within the finer grained less permeable but potentially highly reactive media in this study the heterogeneity of the reductive capacity of an aquifer selected for water reuse projects was characterised the amount type and reactivity of the sedimentary reductants present determined and the relationship between reductive capacity and sedimentary lithologies quantified the average potential reductive capacities prctot based on total organic c and pyrite concentrations of the sediment were quantified for sands 382 lmol o2 g 1 clays 1522 lmol o2 g

characteristics and formation mechanism of multi source mixed sedimentary rocks in a saline lake a case study of the permian lucaogou formation in the jimusaer sag northwest china abstract the permian lucaogou formation in the jimusaer sag of the southeastern junggar basin in china is an uncommon set of mixed sedimentary rocks the mixed sediment content of the lucaogou formation is unusual due to the large amounts of tuffaceous material which makes the system more complex than the commonly mixed siliciclastic carbonate rocks in this study the volcanic material acts as a third end member component in a multi source mixed sedimentary system therefore a new type of mixed siliciclastic carbonate tuffaceous rocks has been introduced methods including core observations thin section analysis grain size measurements and x ray diffraction are used to investigate the characteristics of mineral components sedimentary structures and lithological assemblages in upper and lower sections of the formation these analyses are then used to determine the lateral distribution area of mixed sedimentation sedimentary mixing processes originally described for siliciclastic carbonate systems are used and expanded here for the multi source mixed rocks in a saline lacustrine basin controlling factors on mixed sedimentation included climate change lake level fluctuation tectonic activity and sediment supply rate mentioned in previous studies as well as variations of energy levels in different parts of the lake mixed depositional models for the lower and upper sections of the lucaogou formation in saline lacustrine basin have been established respectively

isotope evolution and contribution to geochemical investigations in aquifer storage and recovery a case study using reclaimed water at bolivar south australia aquifer storage and recovery asr is an important resource management tool whereby water from an available source is stored in a suitable aquifer for later use in periods of higher demand important issues in asr includemaintaining the injection rate and recovering water of suitable quality both of these depend on subsurface biogeochemical processes this paper investigates the use of deuterium 1 8 o 1 3 c 1 4 c and 3 4 s in understanding the reactions induced by reclaimed water injection in a carbonate aquifer at bolivar south australia additionally the injection scheme provides a natural laboratory to observe the process of carbon isotope exchange the injectant deuterium 6 4 2 9 versus vienna standard mean ocean water v smow and 1 8 o 0 9 0 5 v smow signature is more enriched and variable than the native groundwater signature of 26 1 and 4 4 0 1 respectively the variability of the injectant signature is maintained with injectant migration and is useful in constraining the portion of the injected end member reaching observation wells effluent treatment results in total dissolved inorganic carbon tdic enriched in 1 3 c 3 3 2 5 versus pee dee belemnite and modern carbon 100 7 per cent modem carbon pmc which is distinct from the native groundwater comparatively depleted in 1 3 c 11 1 and 1 4 c 5 6 2 1 pmc the carbon isotopic signature in groundwater 4 m from the asr well is dominated by the injectant signature modified by some organic matter oxidation and calcite dissolution however with further migration to the 50 m radius both 1 3 c and 1 4 c signatures are dominated by isotopic exchange with the matrix surface initially in equilibrium with the ambient groundwater and little overall dissolution during storage biogeochemical processes including sulphate reduction and methanogenesis are dominant near the asr well these are indicated by a sulphate decline of up to 1 5 mmol l 1 with around 12 enrichment in the residual sulphate versus canyon diablo troilite and the addition of tdic enriched in 1 3 c while maintaining a modern 1 4 c activity

seagrass meadow sedimentary facies in a mixed siliciclastic carbonate temperate system in the tyrrhenian sea pontinian islands western mediterranean abstract the paper presents the characteristics of surface sediments in a seagrass dominated environment of the inner shelf of the pontinian islands tyrrhenian shelf central mediterranean the aims of this work are to characterize the carbonate production and sedimentary processes of a representative high latitude temperate posidonia oceanica dominated area to discuss the role of seagrass in the siliciclastic carbonate mixing processes which provide analogs for interpreting the occurrence and importance of these types of deposits in the rock record the majority of sediments are poorly sorted siliciclastic skeletal sand based on grain type and abundance and carbonate content these deposits include six subfacies the different subfacies reflect environmental changes within the seagrass environment associated with variations in light penetration and hydrodynamic conditions additionally the seagrass facies range from purely carbonate to mixed carbonate siliciclastic depending on the amount of siliciclastic input and on the capacity of seagrasses to trap allochthonous sediments while hosting carbonate producing biota the type of substrate and the erosion and transport processes control the siliciclastic input in these pontinian seagrass meadows sedimentary facies contain abundant siliciclastic grains produced by erosion of the volcanic substrate and trapped by seagrass blades and rhizomes this pontinian example illustrates that in heterozoan dominated seagrass settings mud producing green algae are not present or are not calcifying and consequently seagrass deposits are much more grainy than photozoan counterparts ancient heterozoan tropical seagrass deposits likely will be discriminated from their temperate or subtropical counterparts only by careful taxonomic analysis of skeletal grains

use of isotope fractionation of sulfate sulfur and sulfate oxygen to assess bacterial desulfurication in a sandy aquifer abstract the unconfined aquifer of the fuhrberger feld consists of 20 30m sands and gravelly sands with unevenly distributed reduced sulfur compounds and small lignitic pebbles in vertical direction two hydrochemically different zones with specific solute transformations are present an upper portion with bacterial denitrification with reduced sulfur compounds as electron donors and a deeper portion with hydrochemical indications of reduction of the aqueous sulfate in the study area ten multilevel groundwater sampling wells were installed sampling and interpretation was based on a two dimensional vertical plane groundwater flownet and on the knowledge of the landuse upgradient of the multilevel wells the concentration and isotopic composition of the sulfate at the entrance into the zone of sulfate reduction is controlled by sulfate of groundwater recharge as well as sulfate formed during denitrification the recharge sulfate shows clear landuse specific differences in concentration and isotopic composition under arable land an average concentration of 60 mg so 4 l 1 with values of 34 s close to 3 cdt diablo meteorite standard canon and of 18 o about 8 standard mean ocean water smow was measured whereas under coniferous forest an average of 100 mg so 4 l 1 with 34 s 2 and 18 o 4 5 was found in the denitrification zone no significant sulfur isotope fractionation occurs during oxidation of reduced sulfur the oxygenisotopic composition of the newly formed sulfate denitrification sulfate depends on the 18 o content of nitrate acting as oxygen donor and on the 18 o content of groundwater in which the oxidation occurs under certain assumptions a 18 o 0 54 was calculated for the oxygen of the newly formed sulfate consequently with increasing sulfate concentrations i e with the admixture of denitrification sulfate a decrease of the 18 o values from about 8 to 2 was observed in the zone of sulfate reduction both the 34 s and 18 o values of the residual sulfate increase with decreasing sulfate concentrations thus proving the existence of bacterial reduction of the aqueous sulfate this sulfate reduction follows a rayleigh process with calculated enrichment factors of 34 9 7 for 34 s and 18 6 for 18 o respectively a plot of 34 s vs 18 o gives a good linear correlation with a slope close to 1 1 4 data on concentration and isotopic composition of sulfate and on the hydraulically derived groundwater age are used for kinetic considerations the results of a multilevel well for depths between 10 and 17m are given as an example the bacterial reduction can be considered as first order reaction with a half life between 75 and 100 years

hydrogeochemical patterns processes and mass transfers during aquifer storage and recovery asr in an anoxic sandy aquifer abstract the hydrogeochemical processes that took place during an aquifer storage and recovery asr trial in a confined anoxic sandy aquifer herten the netherlands were identified and quantified using observation wells at 0 1 8 and 25 m distance from the asr well oxic drinking water was injected in 14 asr cycles in the period 2000 2009 the main reactions consisted of the oxidation of pyrite sedimentary organic matter and adsorbed fe ii and mn ii in all aquifer layers a d whereas the dissolution of carbonates mg calcite and mn siderite occurred mainly in aquifer layer d extinction of the mobilization of so4 fe ii mn ii as co ni ca and total inorganic c pointed at pyrite and calcite leaching in layer a whereas reactions with mn siderite in layer d did not show a significant extinction over time iron ii and mn ii removal during recovery was demonstrated by particle tracking and pointed at sorption to neoformed ferrihydrite part of the oxidants was removed by neoformed organic material in the asr proximal zone 0 ca 5 m where micro organisms grow during injection and die away when storage exceeds about 1 month anoxic conditions during storage led to increased concentrations for a o fe ii mn ii and nh4 as noted for the first 50 200 m3 of abstracted water during the recovery phase with a mass balance approach the water sediment reactions and leaching rate of the reactive solid phases were quantified leaching of pyrite and calcite reached completion at up to 8 m distance in layer a but not in layer d the mass balance approach moreover showed that mn siderite in layer d was probably responsible for the mn ii exceedances of the drinking water standard 0 9 mol l in the recovered water leaching of the mn siderite up to 8 m from the asr well would take 1600 more pore volumes of drinking water injection on top of the realized 460

modeling of carbon cycling and biogeochemical changes during injection and recovery of reclaimed water at bolivar south australia 1 managed aquifer recharge is an increasingly popular technique to secure and enhance water supplies among a range of recharging techniques single well aquifer storage and recovery asr is becoming a common option to either augment drinking water supplies or facilitate reuse of reclaimed water for the present study a conceptual biogeochemical model for reclaimed water asr was developed and incorporated into an existing reactive multicomponent transport model the conceptual and numerical model for carbon cycling includes various forms of organic and inorganic carbon and several reactive processes that transfer carbon within and across different phases the major geochemical processes considered in the model were microbially mediated redox reactions driven by the mineralization of organic carbon mineral dissolution precipitation and ion exchange the numerical model was tested and applied for the analysis of observed data collected during an asr field experiment at bolivar south australia the model simulation of this experiment provides a consistent interpretation of the observed hydrochemical changes the results suggest that during the storage phase dynamic changes in bacterial mass have a significant influence on the local geochemistry in the vicinity of the injection extraction well farther away from the injection extraction well breakthrough of cations is shown to be strongly affected by exchange reactions and in the case of calcium by calcite dissolution

isotopic and microbiological signatures of pyrite driven denitrification in a sandy aquifer denitrification driven by pyrite oxidation can play a major role in the removal of nitrate from groundwater systems as yet limited information is available on the interactions between the micro organisms and aqueous and mineral phases in aquifers where pyrite oxidation is occurring in this study we examine the groundwater and sediment composition along a well characterized redox gradient in a heavily nitrate polluted pyritic sandy aquifer in oostrum the netherlands to identify the sequence of steps involved in denitrification coupled to pyrite oxidation multi isotope analyses 15n no3 18o no3 34s so42 18o so42 and 34spyrite confirm that pyrite is the main electron donor for denitrification at this location enrichment factors derived from the observed changes in nitrate isotopic composition range from 2 0 to 10 9 for e15n and from 2 0 to 9 1 for e18o the isotopic data indicate that pyrite oxidation accounts for approximately 70 of the sulfate present in the zone of denitrification solid phase analyses confirm the presence of pyrite and organic matter rich clay lenses in the subsurface at oostrum in addition sulfur xanes and iron xas results suggest the presence of a series of intermediate sulfur species elemental sulfur and so32 that may be produced during denitrification consistent with geochemical analysis 16s rrna gene sequencing revealed the presence of bacteria capable of sulfide oxidation coupled to nitrate reduction and that are tolerant to high aqueous metal concentrations 2012 elsevier b v

orbital forcing recorded in subtidal cycles from a lower miocene siliciclastic carbonate ramp system central italy metre scale siliciclastic carbonate cycles are the basic depositional motif of the lower miocene guadagnolo formation outcropping in the central apennines the mechanisms which formed the mixed lithology cycles are still a matter of debate the mixed siliciclastic carbonate system discussed in this paper provides a new case study to illustrate the role of orbital forcing in controlling the facies evolution and cyclic stacking of small scale sequences deposited on the outer sector of a ramp two sections are discussed that display mixed siliciclastics and carbonates arranged in upward shallowing cycles each cycle shows an upward decrease in the terrigenous input and a parallel increase in benthic fauna time series analyses indicate the cyclic carbonate terrigenous pattern to be largely controlled by orbital forcing in the milankovitch frequency band coupling of climate change and sea level fluctuations in tune with orbital cycles are proposed as driving mechanisms

shelf edge delta and reef development on a mixed siliciclastic carbonate margin central great barrier reef the great barrier reef gbr is the world s largest extant mixed silicilastic carbonate margin previous research on the great barrier reef has suggested that the extensive barrier reef system may act as an impermeable barrier and limit the development of delta systems during lowstands but sufficient geophysical data to support this hypothesis are lacking we use dense sparker seismic and sub bottom profiler data to better understand the structure of a large lobe shaped feature 10 km 10 km on the shelf edge of the central gbr and the interactions between siliciclastic and carbonate sedimentary systems interpreted sparker seismic contains prograding clinoforms and suggest that the lobe shaped feature was a river dominated shelf edge delta a delta on the shelf edge implies that the presence of an exposed barrier reef was not a major impediment to deposition and that other adjacent lobe shaped features are also deltaic deposits the shelf edge deltas were deposited onto a broad upper slope terrace that allowed continued progradation and limited incision when sea level fell below the shelf edge delta foresets are commonly colonized by coral reefs but the spatial and temporal relationship between reefs and some deltaic units remains unclear the presence of multiple shelf edge deltas that link to previously mapped burdekin river paleo channels indicates a complex history of sedimentation with the burdekin river delta migrating up to 100 km along the gbr margin during the late quaternary regional bathymetric data suggest that large modern or recent shelf edge deltas are rare on the gbr and that there was a broad range of sedimentary processes operating along the margin of the gbr during periods of low sea level