chlorine stable isotope evidence for salinization processes of confined groundwater in southwestern nobi plain aquifer system central japan summary a confined aquifer system isolated from modern seawater is developed in argillaceous marine and freshwater sediments of pliocene holocene age in southwestern nobi plain swnp central japan a tongue of brackish confined groundwater cl 1000 mg l which extends from the shoreline of ise bay inland mostly has negative 37 cl values with 0 90 to 0 21 the cl isotopic compositions are negatively correlated with paleo seawater cl concentrations discriminated by a rayleigh distillation model with 34 s values while they are not correlated with either total cl concentrations or 34 s values furthermore cl concentrations from modern seawater are positively correlated with 37 cl values in addition to these observations diffusion model calculations suggest that paleo seawater cl has diffused out from argillaceous marine sediments whereas modern seawater cl has not been affected by preferential diffusion of cl isotopes because it has migrated by advection via both an unconfined aquifer and non pumping wells moreover the brackish groundwater is characterized by an excess of na cl ratio and deficits of mg cl and ca cl ratios compared to those predicted from simple mixing of freshwater with seawater this would be caused by cation exchange reactions in the confined aquifer system in which groundwater is freshening after salinization by both paleo seawater and or modern seawater

assessment of mineralogical and petrographic factors affecting petro physical properties strength and cracking processes of volcanic rocks abstract microtextural features influence the petrophysical and mechanical properties of rocks including the elastic properties and cracking processes under axial loads volcanic rocks with varying microtextural characteristics and compositions were evaluated to assess the effect of the main constituents mineralogical petrographic and micro structural features on the petrophysical properties elastic properties and strength furthermore detailed analyses were also used to understand the cracking processes under axial loads the analyses of the cracking processes were completed on thin sections obtained from the mechanically tested specimens the results from the quantitative mineralogical and petrographic studies and observations from thin sections revealed that the mineral mass fractions have an effect on the specific gravity and loss on ignition loi values on the other hand unconfined compressive strength ucs and elastic properties are mostly affected by petrographic variables e g mineral content the ucs values tend to decrease with a relative increase in the groundmass with respect to the phenocryst content and vice versa biotite is the only mineral that influences the ucs individually geometric features e g feret s diameter and perimeter of opaque minerals and biotite are determined to be important constituents influencing the young s modulus under axial loads crack propagation is strongly dependent on the proportional distribution of the phenocryst and groundmass it was observed that increasing groundmass content leads to predominantly axial cracks the cracks tend to bend or propagate as a boundary crack when they reach the boundary of an unaltered phenocryst thus axial and shear cracks co exist with increasing amounts of phenocrysts which hinders crack propagation occasionally cracks can penetrate the altered or opaque phenocrysts depending on the degrees of orientation with respect to applied load of the same minerals furthermore the synthesis of the measurements obtained from ucs tests and thin section observations reveals that an increase in the amount of phenocrysts which promote the formation of more shear cracks in addition to axial cracks causes an increase in the radial strain and poisson s ratio the other factors investigated had minor effects on physical and mechanical properties of studied rocks

controls on the δ34s and δ18o of dissolved sulfate in the quaternary aquifers of the north china plain summary the north china plain ncp is a typical cenozoic sedimentary basin and one of the largest alluvial plains in eastern asia it consists of piedmont alluvial plain central alluvial lacustrine plain and littoral alluvial plain from west to east where quaternary aquifer systems developed in different depths groundwater from these aquifers is the most important water resource and supports a population of 200 million in the ncp currently the quaternary groundwater is depleting fast due to both human and natural factors characterizing biogeochemical processes in groundwater is central to understanding groundwater chemistry to identify the sources of dissolved sulfate so 4 2 and address subsequent biogeochemical processes in groundwater we conducted a study of spatial distributions of 34sso4 and 18oso4 in the quaternary aquifers in the northern part of the ncp the so 4 2 34sso4 and 18oso4 along the west east groundwater flowpaths in the three alluvial plains are analyzed and examined the quaternary groundwater 20 c has a so 4 2 of 37 25 177 41 mg l with so 4 2 cl ratios ranging from 0 12 to 2 79 the 34sso4 and 18oso4 range from 4 9 to 30 9 and from 4 7 to 14 0 respectively supported by other geochemical and isotopic parameters such as total dissolved solids tds concentrations d and 18o of groundwater d and 18oh2o and 14c contents in groundwater our study concludes that 1 the shallow groundwater in the piedmont area is characterized by higher so 4 2 concentration of 153 22 mg l with 34sso4 of 10 0 14 5 and 18oso4 of 4 7 9 0 whereas the groundwater in the piedmont area is characterized by lower so 4 2 concentration of 37 25 mg l with 34sso4 of 4 9 7 3 and 18oso4 of 5 8 7 5 therefore the so 4 2 in the shallow groundwater is dominated by weathered sulfate minerals from the taihang mountains and sulfate derived from oxidation of sulfides in infiltration paths whereas the so 4 2 in the deep groundwater is dominated by atmospheric sulfate from precipitation and sulfate derived from decomposition of organic matter during its recharge processes 2 dissimilatory microbial sulfate reduction dmsr occurred in the deep confined aquifers in both central and littoral plains where 34sso4 and 18oso4 increase along the groundwater flowpaths and present specific patterns for each aquifer which imply variable contributions from dmsr processes 3 the deep confined aquifer in the littoral plain has a lower dmsr rate than the other aquifers probably due to the effect of its lower permeability on physical exclusion of bacteria from the aquifer matrix this study can provide a biogeochemical background for assessing groundwater evolution and its quality in the ncp

controls on the distribution of major ions in pore waters of a thick surficial aquitard transport and geochemical processes controlling the chemical and isotopic composition of pore waters in the upper 45 m of a thick surficial clay rich till battleford formation were studied the upper 3 m of the till is oxidized and fractured the remaining 77 m of the till the aquitard is nonfractured and unoxidized concentrations of total dissolved solids so42 na mg2 and k decrease with depth through the unoxidized zone to a depth of about 15 m below ground below which the concentrations remain constant a similar trend was observed for alkalinity however the decrease in concentration occurs over 20 m in contrast to these ions ca2 concentrations increase with depth through the upper 20 m unoxidized zone below which the concentrations remain relatively constant the distribution of dissolved ions shows the presence of two end members elevated solute concentrations in the oxidized zone attributed to geochemical weathering that occurred since the start of the holocene and connate pleistocene age water at depths between 20 and 45 m abiotic and biotic geochemical reaction rates in the aquitard were shown to be extremely slow or not occurring

deriving spatial and temporal patterns of coastal marsh aggradation from hurricane storm surge marker beds abstract this study uses storm surge sediment beds deposited by hurricanes audrey 1957 carla 1961 rita 2005 and ike 2008 to investigate spatial and temporal changes in marsh sedimentation on the mcfaddin national wildlife refuge in southeastern texas fourteen sediment cores were collected along a transect extending 1230 m inland from the gulf coast storm surge deposited sediment beds were identified by texture organic content carbonate content the presence of marine microfossils and 137cs dating the hurricane derived sediment beds facilitate assessment of changes in marsh sedimentation from nearshore to inland locations and over decadal to annual timescales spatial variation along the transect reflects varying contributions from three prevailing sediment sources flooding overwash and organic sedimentation from marsh plants over about the last decade hurricane overwash has been the predominant sediment source for nearshore locations because of large sediment inputs from hurricanes rita and ike farther inland hurricane inputs diminish and sedimentation is dominated by deposition from flood waters and a larger organic component temporal variations in sedimentation reflect hurricane activity changes in marsh surface elevation and degree of compaction of marsh sediments which is time dependent there was little to no marsh sedimentation in the period 2008 2014 firstly because no hurricanes impacted the study area and secondly because overwash sedimentation prior to 2008 had increased nearshore marsh surface elevations by up to 0 68 m reducing subsequent inputs from flooding marsh sedimentation rates were relatively high in the period 2005 2008 averaging 2 13 cm year and possibly reflecting sediment contributions from hurricanes humberto and gustav however these marsh sediments are highly organic and largely uncompacted older deeper marsh deposits formed between 1961 and 2005 are less organic rich more compacted and have an average annual sedimentation rate of 0 38 cm year which is closely comparable to long term sedimentation rates in similar marsh settings nearby these results demonstrate the utility of using hurricane storm surge marker beds to investigate marsh sedimentation provide insights into the sedimentary response of coastal marshes to hurricanes and provide useful guidance to public policy aimed at combating the effects of sea level rise on coastal marshes along the northern gulf of mexico

storm induced hydrodynamics and sediment transport in a coastal louisiana lake abstract coupled hydrodynamic modeling and sediment core analysis was used to investigate hurricane rita hydrodynamic conditions and associated sediment dynamics in sister lake a shallow coastal lake in terrebonne basin louisiana tropical cyclone impacts on wetland terrestrial and shelf systems have been previously studied and reasonably delineated but little is known about the response of coastal lakes to storm events this initial investigation of tropical cyclone impacts on a shallow coastal lake clarifies sediment transport and deposition patterns in a geologically complex deltaic region modeling results from hurricane rita forcing conditions hindcast a maximum storm surge elevation of approximately 1 1 m and a significant wave height of 1 0 m in sister lake bed shear stresses across almost the entire model domain leading up to hurricane rita s landfall were above the critical value causing erosion of fine grained bottom sediments and quickly decreased in the western portion during rita s landfall indicating significant deposition in this western portion of the lake the ideal event sedimentation unit that would result from the storm conditions hindcast from the numerical model was corroborated with stratigraphy identified in box cores sedimentary units with an erosional base overlain by recently deposited silty material topped by clays this study provides a fundamental understanding of lake bottom characteristics and impacts of storm related physical processes on erosion and deposition

controls on bacterial sulphate reduction in a dual porosity aquifer system the lincolnshire limestone aquifer england abstract chemical and sulphur isotopic analyses are presented of fissure waters and pore waters in the deep confined zone of a dual porosity carbonate aquifer some of the fissure waters show good evidence for bacterial sulphate reduction with low concentrations of sulphide present which is strongly to moderately depleted in 34 s relative to sulphate the sulphur geochemistry is best interpreted as mixing between i a reduced water with sulphide 60 depleted in 34 s relative to sulphate and ii a sulphate rich water from up dip in the aquifer in addition sulphide oxidation occurs where sufficiently oxidizing water is drawn in by abstractions the large isotope fractionation factor associated with the sulphidic waters is probably the result of redox cycling of sulphur with little net reduction rather than a true kinetic fractionation factor by contrast pore waters in the sulphate reducing zone show little or no evidence for the effects of sulphate reduction despite the fact that the pore waters represent a significant reservoir of sulphate for reduction some pore waters have been modified recognizably by diffusional exchange with the fissure waters but the aquifer matrix has not been colonized by sulphate reducing bacteria probably because porethroats in the limestone are too small for bacteria to pass physical exclusion of bacteria from the aquifer matrix and limited diffusional exchange are likely to exert fundamental controls on bacterial redox processes in dual porosity aquifer systems and other systems with low permeability due to small pore interconnections

reactivity of pyrite and organic carbon as electron donors for biogeochemical processes in the fractured jurassic lincolnshire limestone aquifer uk abstract in this study the weathering profiles of limestone blocks in the jurassic lincolnshire limestone uk are used to determine the spatial variation in concentration of electron donors organic carbon and pyrite that might drive subsurface microbial respiration including denitrification organic carbon concentrations were found to be constant throughout the block transects in contrast sulphur and pyrite iron concentrations were significantly higher in the unweathered zones in comparison to the weathered zones moreover acid extractable iron concentrations were significantly higher in the weathered zones in comparison to those of the unweathered zones this suggests that pyrite is operating as the main electron donor in this system and that organic carbon is unreactive therefore potentially beneficial microbial processes such as denitrification of agrochemically contaminated groundwater will be limited not by availability of organic carbon but by availability of pyrite

mechanical limits to microbial activity in deep sediments the observed decline in microbial abundance with increasing depth has been associated to various environmental factors meanwhile the role of geometrical constraints and soil bacteria mechanical interactions remains poorly analyzed pore and pore throat sizes may restrict habitable pore space and traversable interconnected porosity and sediment cell interaction may cause puncture or tensile failure of the cell membrane in this study we compile published evidence on the presence of bacteria in deep sediments as well as pore and pore throat size data in sediments at different depths to establish possible geometrical conditions for the sediment cell complex compiled data are complemented with experimental results gathered through controlled axial compression experiments that reproduce the mechanical consolidation of deep sediment sequences then we analyze the mechanical interaction between bacteria and sediments that may cause cell death finally we combine data and model predictions to define the main regions in a particle size versus depth space that characterize the fate of bacteria active and motile trapped inside pores and dead or dormant these regions constrain hypotheses related to the role of biological activity in deep sediments research protocols and sampling methods the viability of bioremediation strategies for contaminated sites and the potential development of bioengineered sediments

an evaluation of the use of the chromous chloride reduction method for isotopic analyses of pyrite in rocks and sediment abstract the use of chromous chloride reduction as a preparation technique for isolation of pyrite sulphur for isotopic analysis has been assessed a small but consistent fractionation is introduced by reduction of pyrite to h 2 s enriching the yield in 34 s by 0 55 0 14

lithological controls on biological activity and groundwater chemistry in quaternary sediments depth profiles of solute chemistry and sulfate isotopic compositions are presented for groundwater and pore water in a sequence of quaternary glacial outwash sediments sand units show evidence for hydraulic connection to the surface and thus modern sources of solutes finer grained sediments show a general pattern of increasing solute concentrations with depth with sulfate derived from ancient rainwater and pyrite oxidation in the soil drift in these sediments sulfate has undergone bacterial sulfate reduction bsr to produce biogenic sulfide in clay sediments with d10 1 6 m high concentrations of sulfate and acetate now co exist implying that bsr is inhibited the correlation with smaller sediment grain size indicates that this is due to pore size exclusion of the sulfate reducing bacteria mechanical restriction of microbial function thus provides a fundamental limitation on microbial respiration in buried clay rich sediments which acts as a control on the chemical evolution of their pore waters copyright 2009 john wiley sons ltd

isotopic evidence for anoxic pyrite oxidation and stimulation of bacterial sulphate reduction in marine sediments pore water sulphate concentrations show marked increases at depths 50 m at odp sites 888 and 890 889 from the cascadia margin accretionary wedge in the uppermost 10 m sulphate concentrations decrease with depth and sulphate 34 s and 18 o increase as sulphate is removed by bacterial sulphate reduction isotopic data show that sulphate formed below 50 m results from oxidation of early diagenetic pyrite and that oxygen in the sulphate molecules is derived from pore water fe 3 in the sediment is the probable oxidizing agent the increased sulphate concentrations stimulate bacterial sulphate reduction at depths of 70 250 m and are thus important in sustaining deep bacterial activity

processes affecting groundwater chemistry in a zone of saline intrusion into an urban sandstone aquifer abstract samples have been collected from inflows into railway tunnels in the triassic sandstone aquifer beneath liverpool and the mersey estuary england u k these provide a profile through a saline freshwater mixing zone analyses were made of major anions and cations 34s and 18o in so4 13c in dissolved inorganic c and 87sr 86sr the data demonstrate that the presence of a low permeability fault exerts a strong control on the local groundwater chemistry on the estuary side of the fault groundwater chemistry is dominated by mixing of intruding estuary water which is modified by so4 reduction and calcite dissolution with fresh groundwater the environment of so4 reduction in the tidal estuary is one of repeated reduction and re oxidation of s in an open system and has resulted in virtually no change in s isotopic composition but an enrichment in residual so4 18o of 1 5 groundwater chemistry on the landward side of the fault is primarily the result of recharge in an urban environment there is also evidence that saline water has been present in this region of the aquifer in the past and that this has now been flushed by fresh groundwaters this saline water was either transported along the landward side of the fault from nearer the estuary or more probably transmitted across the fault both mechanisms would have been driven by large landward head gradients caused by heavy industrial abstraction earlier this century this has produced a zone of groundwaters depleted in ca and radiogenic sr and enriched in na as a result of ion exchange between the fresh groundwaters and the aquifer previously occupied by more saline water sulphur isotopic composition however shows no variation since so4 does not undergo significant ion exchange a tracer test from a borehole to the tunnels showed multiple breakthroughs to some locations indicating a number of different flow paths through the aquifer the maximum flow velocity recorded in this test was 140 m d suggesting flow along fractures

origin and distribution of sulfate in a fractured till in southern alberta canada glacial till in a 22 km sup 2 area of the interior plains region of southern alberta canada consists of an upper brown gypsiferous weathered zone up to 20 m thick and a lower discontinuous grey nonweathered zone up to 25 m thick although the total sulfur content of the two till zones is the same 0 34 the mean total sulfate content of the weathered till 4 0 mg g sup 1 exceeds that the nonweathered till 0 8 mg g sup 1 similarities suggest that all so sub 4 sup 2 in the nonweathered till and 20 of the sulfate in the weathered till was derived from sulfate rich bedrock fragments incorporated in the till during deposition laboratory experiments and delta sup 18 o and delta sup 34 s analyses of total so sub 4 sup 2 and the sulfur forms in the two zones show that the majority of the sulfate in the weathered till was derived from the oxidation of organic s at some time after the till was deposited mass balance and flux calculations indicate that this oxidation occurred under partially saturated conditions groundwater flow simulations suggest that the water table was much lower and that a thick partially saturated zone was possible during the drier altithermal period 11 000more to 3000 years b p the following chemical processes account for the major ions that are found in the groundwater but were generated when the partially saturated zone existed the oxidation of reduced s produced so sub 4 sup 2 and h sup the h sup reacted with carbonate minerals under elevated p sub co2 with ca sup 2 loss by exchange for na sup and gypsum precipitation volume shrinkage in the weathered till resulting from these geochemical processes may have enhanced the development of fractures and caused the associated increased hydraulic conductivity less

the use of environmental isotopic c sr s and hydrochemical tracers to characterize anthropogenic effects on karst groundwater quality a case study of the shuicheng basin sw china rapidly increasing populations and associated intensification of agriculture urbanization and industrialization place increased demands on water resources and increased likelihood of pollution in many areas of the world the shuicheng basin southwestern china is one such area and in order to understand water rock interactions carbonate dissolution and anthropogenic impacts on groundwater quality in this karstic landform dominated area chemical as well as c sr and s isotopic compositions of groundwater spring and well and surface water river were measured during and following rainy seasons the concentrations of various ions in groundwater were characterized by the dominant cations ca2 mg2 and anions hco3 so42 which account for more than 80 of the total ion concentration strontium isotope ratios 87sr 86sr 0 70760 0 70918 mean 0 70831 and 13cdic 14 2 to 8 4 mean 10 7 indicate that the weathering dissolution of limestone controls ca2 and hco3 the decrease in 13cdic values with increasing concentrations of anthropogenic species cl no3 and na shows that the c isotopic composition of dic can be a useful tracer of contaminants chemical compositions hydrogeological conditions and 34s analyses showed increasing so42 concentration resulting from domestic wastewater fertilizer applications atmospheric inputs through coal combustion and oxidation of sulfide minerals which typically are abundant in coal formations in the basin groundwater from the old downtown industrial and agricultural areas exhibited high concentrations of cl no3 so42 and na suggesting the groundwater is impacted by significant levels of contamination from human activities

a δ34s isoscape of total sulphur in soils across northern ireland abstract a map of the spatial variation in isotopic composition of a substrate or isoscape provides a tool to address a range of research questions such as the use of isotope fingerprinting to identify the origin of compounds the focus of this study was to establish a soil s isotope map for northern ireland in order to investigate spatial variability within the isotopic composition of total soil sulphur s the sample resolution was about one sample every 141 km 2 34 s values were grouped based on soil type and soil parent material total soil s 34 s data were grouped according to soil type to evaluate whether a soil s characteristics affect its isotopic composition gleyed soils had a mean 34 s value of 6 3 6 1 lower than the means for other soil types a trend towards higher 34 s values mean 34 s of 13 8 6 0 was observed in soils with a high organic matter content no trends in 34 s value were observed for other soil types there were no discernible correlations between total soil s 34 s and soil parent material with the exception of shale and mudstones the majority of soils derived from shale and mudstones had 34 s values at or close to the mean of 4 9 a spatially coherent pattern of relatively high soil total s 34 s values in the west and north and low in the se is discernible in northern ireland based on the observed spatial distribution it has been concluded that the quantity and source anthropogenic or marine of wet atmospheric s deposition is a controlling factor on regional variation of soil 34 s in northern ireland this s isoscape will assist studies of s cycling in northern ireland and may assist in the creation of an isotopic fingerprint for a potential input source needed to interpret data in traceability studies

using dual isotopic data to track the sources and behaviors of dissolved sulfate in the western north china plain abstract this paper investigated the sources and behaviors of sulfate in groundwater of the western north china plain using sulfur and oxygen isotopic ratios the groundwaters can be categorized into karst groundwater kgw coal mine drainage cmd and pore water subsurface saturated water in interstices of unconsolidated sediment pore water in alluvial plain sediments could be further classified into unconfined groundwater ugw with depth of less than 30 m and confined groundwater cgw with depth of more than 60 m the isotopic compositions of kgw varied from 9 3 to 11 3 for 34 s so4 with the median value of 10 3 n 4 and 7 9 to 15 6 for 18 o so4 with the median value of 14 3 n 4 respectively indicating gypsum dissolution in karst aquifers 34 s so4 and 18 o so4 values of sulfate in cmd ranged from 10 8 to 12 4 and 4 8 to 8 7 respectively on the basis of groundwater flow path and geomorphological setting the pore water samples were divided as three groups 1 alluvial proluvial fan ii 1 group with high sulfate concentration median values of 2 37 mm and 1 95 mm for ugw and cgw respectively and positive 34 s so4 and 18 o so4 values median values of 8 8 and 6 9 for ugw 12 0 and 8 0 for cgw 2 proluvial slope ii 2 group with low sulfate concentration median values of 1 56 mm and 0 84 mm for ugw and cgw respectively and similar 34 s so4 and 18 o so4 values median values of 9 0 and 7 4 for ugw 10 2 and 7 7 for cgw and 3 low lying zone ii 3 group with moderate sulfate concentration median values of 2 13 mm and 1 17 mm for ugw and cgw respectively and more positive 34 s so4 and 18 o so4 values median values of 10 7 and 7 7 for ugw 20 1 and 8 8 for cgw in the present study three major sources of sulfate could be differentiated as following sulfate dissolved from ordovician to permian rocks 34 s so4 10 35 and 18 o so4 7 20 soil sulfate 34 s so4 5 9 and 18 o so4 5 8 and sewage water 34 s so4 10 0 and 18 o so4 7 6 kinetic fractionations of sulfur and oxygen isotopes as a result of bacterial sulfate reduction bsr were found to be evident in the confined aquifer in stagnant zone ii 3 and enrichment factors of sulfate sulfur and sulfate oxygen isotopes calculated by rayleigh equation were 12 1 and 4 7 respectively along the flow direction of groundwater at depths of 60 100 m the results obtained in this study confirm that detailed hydrogeological settings and identification of anthropogenic sources are critical for elucidating evolution of 34 s so4 and 18 o so4 values along with groundwater flow path and this work also provides a useful framework for understanding sulfur cycling in alluvial plain aquifers

coastal wetland response to sea level rise in connecticut and new york abstract the persistence of salt marshes in the landscape depends on their ability to accommodate rising sea level and minimize additional flooding stress we use sediment cores and water level data from 14 marshes in connecticut and new york to evaluate how marsh accretion mineral and organic accumulation carbon storage and hydroperiod have changed from 1900 to 2012 we observe a regional acceleration in marsh accretion beginning around 1940 although marsh accretion did not reach parity with sea level rise for several additional decades despite a rise in marsh accretion from 1 0 mm yr 1 circa 1900 to 3 6 mm yr 1 at present the marsh surface has lost elevation relative to tidal datums declining relative elevations have led to increased tidal flooding particularly in high marsh settings as flooding increased organic matter accumulation accelerated at all marshes accelerating mineral deposition was only observed in areas of short form spartina alterniflora mineral and organic sediment accumulation co limit accretion but organic accumulation was the stronger limiting factor suggesting that marsh response to sea level rise in the region is sensitive to processes affecting rates of belowground production and decomposition marsh carbon storage over the period of study averaged 84 g c m 2 yr 1 increasing as accretion accelerated if marshes remain spatially intact as sea levels rise these results suggest that marshes have the capacity to become even greater c sinks

chloride and chlorine isotopes 36cl and δ37cl as tracers of solute migration in a thick clay rich aquitard system detailed vertical profiles of dissolved cl and its isotopes 36cl and 37cl provided new information on the origin and systematics of this conservative tracer in pore waters of a thick aquitard system the aquitard system consists of surficial quaternary clay rich till 80 m thick deposited 30 20 kyr b p overlying cretaceous marine clay 76 m thick deposited 71 ma the distribution of cl 37cl and br showed the presence of five distinct end members for cl the top of the unoxidized till a regional aquifer underlying the cretaceous clay two localized geological heterogeneities sand streaks in the till and glacial meltwater emplaced with the till and still present at depths of between 36 and 60 m numerical simulations of the transport of cl from the sand streaks indicated that this geochemical profile has been developing throughout most of the holocene the 36cl measurements showed that the age of the dissolved cl in the upper cretaceous clay is likely between 0 75 and 1 9 myr the 36cl measurements further suggested that the dissolved cl in the till was not directly derived from the underlying cretaceous clay finally it was not possible to quantify the effects of isotopic fractionation of 37cl relative to 35cl because of diffusion in this aquitard system

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

sources and impact of sulphate on groundwaters of triassic carbonate aquifers upper silesia poland summary groundwater within the unconfined or semi confined parts of triassic carbonate aquifers in upper silesia poland contains high concentrations of sulphate up to 290 mg l sometimes in excess of drinking water limits 250 mg l to assess the influence of different possible sulphate sources isotopic analyses of s and o were performed on groundwater sulphate and potential sulphate sources and combined with literature data three dominant sources of sulphate were delineated based on the geological and literature study and supported by the mixing relations between inverse concentration of sulphate and its isotopic compositions these sources are i sulphate from rainfall ii weathering of sulphide minerals in ore deposits in the aquifer forming carbonate rocks iii dissolution of sulphate evaporites in the triassic sequence fortunately these three sources have distinctive s and o isotope compositions and thus their contributions to the total dissolved sulphate could be estimated the application of linear mixing models for three sources in the dual isotope system allowed the impact of the three different sulphate sources on particular parts of the aquifers to be calculated the average isotopic composition of sulphate in abstracted groundwater indicates that the most important source of sulphate is sulphide weathering contributing about 50 of total sulphate the second most significant source of sulphate input is rainfall and it is characterised by a mean contribution of 30 application of monte carlo analysis that incorporates the full variability in distributions of isotopic compositions for the three sources and all mixing fractions between them gave the most probable ranges of the dissolved in groundwater sulphate this analysis indicated that the proportion of sulphate derived by sulphide oxidation is comparable with the estimations based on linear models this study has shown that the water quality of these important groundwater resources is under threat from both natural sources i e metal sulphide oxidation and gypsum dissolution analysis of the mathematical models analysis shows that the first process is the predominant source of sulphate in groundwater however the highest concentrations of dissolved sulphate are positively correlated with the increasing proportion of sulphate derived from gypsum dissolution moreover one should keep in mind that natural processes might be anthropogenically accelerated due to variable water demands and groundwater abstraction eventually the statistically second order source of sulphate rainfall might contain surface derived contaminants and its contribution to the total load of sulphate might indirectly indicate the vulnerability of aquifers for the pollution

sea water groundwater interactions along a small catchment of the european atlantic coast abstract the geochemistry and isotopic composition of a karstic coastal aquifer in western ireland has shed light on the effect of sea water groundwater interactions on the water quality of ireland s atlantic coastal zone the use of stable isotope data from the iaea precipitation station in valentia located in sw ireland has facilitated the characterization of groundwater recharge conditions in the western part of ireland and suggests that groundwater is mostly replenished by the isotopically light winter precipitation the dissolved so 4 2 in the karstic groundwater that was collected during baseflow conditions with 34s values between 4 6 and 18 may be composed of s stemming from three principal sources so 4 2 derived from precipitation which is composed of both sea spray s 34s 20 and an isotopically light anthropogenic source 34s 1 5 so 4 2 stemming from animal slurries 34s 5 and intruding sea water so 4 2 34s 20 2 the isotopic composition of 18o in dissolved groundwater so 4 2 collected during baseflow conditions is interpreted as reflecting sea water intrusion to the karstic coastal groundwater system the highest 18o values in dissolved groundwater so 4 2 were in samples collected near the coast 4 8 0 4 and the lowest 2 0 5 were collected further inland the 15n and 18o values of groundwater no 3 were between 3 4 and 11 4 and approximately 7 7 respectively and reflect geochemical conditions in the aquifer that do not promote attenuation of no 3 through denitrification as a result n loading to kinvara bay that is controlled by submarine groundwater discharge sgd was calculated as 5 tons day on average compared to an estimated n input that derives from precipitation of approximately 2 5 tons a sgd into the bay may result in near coastal sea water quality changes these results represent one of the first studies addressing the effect of groundwater quality in ireland on the european atlantic coastal zone

recreating atmospheric sulphur deposition histories from peat stratigraphy diagenetic conditions required for signal preservation and reconstruction of past sulphur deposition in the derbyshire peak district uk three modern pristine and one previously polluted ombrotrophic peat were sampled and analysed to investigate whether the isotopic composition of atmospheric sulphur inputs could be preserved in the organic fraction of ombrotrophic peats without undue alteration through syn depositional or diagenetic effects peat type reflecting the environment of deposition and diagenesis was shown to be critical in determining whether an environmental archive of sulphur deposition could be preserved within the profile of the pristine peats sampled hummock peat from shetland proved to be the most suitable exhibiting a near constant 34s characteristic of the growing vegetation in the organic fraction of peat in the upper 30 cm of the profile however only short to medium term changes 600 years in input are likely to be preserved due to the masking effect produced by incorporation of sulphide derived from bacterial sulphate reduction bsr into the organic fraction at depth the organic fraction of peat sampled from waterlogged pools at forsinard ne scotland was masked by sulphide incorporation throughout the profile while peat from abisko n sweden was exposed to annual freeze thaw cycles which appear to have produced significant decomposition of the organically bound sulphur and loss of the original depositional isotopic signal three peat types were sampled from the southern pennines an area with a gross history of sulphur pollution during the industrial revolution high hummock peat low hummock peat and waterlogged peat from a pool complex in drier high and low hummock peat types diagenesis and decomposition were not found to be significant processes in the upper portions of the peat hence alterations in the isotopic composition of the organic sulphur fraction in the profile reflect that of the depositional environment in the hummock peats organically bound sulphur becomes isotopically lighter at around 1400 ad which may reflect alterations in local sulphur inputs at this time due to the small scale smelting of lead in the area isotopic compositions become progressively lighter still towards the peat surface layers which correlate well with the excesses of sulphur deposition largely from coal burning during the industrial revolution

isotopic composition of sulfate as a tracer of natural and anthropogenic influences on groundwater geochemistry in an urban sandstone aquifer birmingham uk abstract development and management of urban groundwater resources is limited in practice by a lack of knowledge of the nature distribution and sources of groundwater contamination in an urban aquifer that may have had complex land use and abstraction history sulfate is associated with many of the solute sources to urban groundwater and in this study the use of dual isotope 18o and 34s fingerprinting of so 4 2 in groundwater to assess the contribution of different sources to urban groundwater is investigated groundwater 70 locations and surface water samples from the city of birmingham on the triassic sherwood sandstone aquifer have been analyzed for inorganic chemical and so 4 2 isotopic composition isotopic compositions of so 4 2 associated with various solute sources have also been determined sulfate derived from pyrite oxidation during recharge through quaternary drift deposits is characteristically depleted in 18o and 34s compared to other sources and is ubiquitous in unconfined zone groundwater though the contribution from this source has increased markedly following draw down induced by abstraction from the aquifer in unpolluted groundwaters other so 4 2 sources are dissolution of evaporite minerals confined zone and rainfall unconfined zone unfortunately so 4 2 isotopic composition cannot distinguish between made ground i e artificial man made ground usually demolition waste and sewage sources of so 4 2 which constitute the major contributions to so 4 2 in polluted urban groundwater at most sites contributions of so 4 2 from spilt industrial acids do have a distinctive isotopic composition seen at many metal working and former metal working sites estimates of solute contributions derived from these sources derived in this way provide a useful check on the calibration of aquifer and pollutant flux recharge models for urban groundwater

geochemistry of dissolved inorganic carbon in a coastal plain aquifer 1 sulfate from confining beds as an oxidant in microbial co2 production a primary source of dissolved inorganic carbon dic in the black creek aquifer of south carolina is carbon dioxide produced by microbially mediated oxidation of sedimentary organic matter groundwater chemistry data indicate however that the available mass of inorganic electron acceptors oxygen fe iii and sulfate and observed methane production is inadequate to account for observed co2 production although sulfate concentrations are low approximately 0 05 0 10 mm in aquifer water throughout the flow system sulfate concentrations are greater in confining bed pore water 0 4 20 mm the distribution of culturable sulfate reducing bacteria in these sediments suggests that this concentration gradient is maintained by greater sulfate reducing activity in sands than in clays calculations based on fick s law indicate that possible rates of sulfate diffusion to aquifer sediments are sufficient to explain observed rates of co2 production about 10 5 mmoll 1 year 1 thus eliminating the apparent electron acceptor deficit furthermore concentrations of dissolved hydrogen in aquifer water are in the range characteristic of sulfate reduction 2 6 nm which provides independent evidence that sulfate reduction is the predominant terminal electron accepting process in this system the observed accumulation of pyrite and calcite cemented sandstones at sand clay interfaces is direct physical evidence that these processes have been continuing over the history of these sediments