geochemical and mineralogical impacts of h2so4 on clays between ph 5 0 and 3 0 natural and constructed clay liners are routinely used to contain waste and wastewater the impact of acidic solutions on the geochemistry and mineralogy of clays has been widely investigated in relation to acid mine drainage systems at ph 1 0 the impact of h2so4 leachate characterized by ph 1 0 and potentially negative ph values on the geochemistry and mineralogy of clays is however not clear thus laboratory batch experiments were conducted on three natural clay samples with different mass ratios of smectite illite and kaolinite to investigate the impact of h2so4 on the geochemistry and mineralogy of aluminosilicates from ph 5 0 to 3 0 batch testing was conducted at seven ph treatments 5 0 3 0 1 0 0 0 1 0 2 0 and 3 0 using standardized h2so4 solutions for four exposure periods 14 90 180 and 365 d aqueous geochemical and xrd analyses showed increased dissolution of aluminosilicates with decreasing ph and increasing exposure period that smectite was more susceptible to dissolution than illite and kaolinite precipitation of an amorphous silica phase occurred at ph 0 0 and anhydrite precipitated in ca rich clays at ph 1 0 in addition global dissolution rates were calculated for the clays and showed good agreement to literature smectite illite and kaolinite dissolution rates which suggests global dissolution rates for complex clays could be determined from monomineralic studies a stepwise conceptual model of the impact of h2so4 on aluminosilicate geochemistry and mineralogy between ph 5 0 and 3 0 is proposed

leaching experiments to study the release of trace elements from mineral separates from chinese coals abstract leaching experiments were carried out for two samples of mineral separates from chinese coals for the purpose to simulate the release of trace elements in acid mine drainage the leaching solution has a ferric ion concentration of 10 3 m ph 2 the experiments were carried out at room temperature the grain size of the mineral separates is 75 130 m the behavior of the release of eight trace elements co ni zn cd al cr as and pb were measured during the period of 312h the results from four leaching tests using two samples with two solid to liquid ratios show that the concentrations of co ni zn and cd continuously increased during the leaching period and they were correlated with the sulfate content in the same leachate this indicates that the elements were released during the oxidation and dissolution of pyrite the elements were easily dissolved in the leaching solution on the other hand the concentrations of al cr as and pb in the leachates varied considerably under same leaching conditions and were sensitive to the condition of the leachate during the leaching process the release of these four elements was affected by the ph of the leachate and by absorption and co precipitation they are less likely to migrate therefore the release and migration of the eight elements in acid coal mine drainage are controlled mainly by three factors the oxidation of pyrite the ph of the leachate and mineralogy of country rocks

the behavior of trace elements during schwertmannite precipitation and subsequent transformation into goethite and jarosite schwertmannite is a ubiquitous mineral formed from acid rock drainage ard and plays a major role in controlling the water chemistry of many acid streams the formation of schwertmannite was investigated in the acid discharge of the monte romero abandoned mine iberian pyrite belt sw spain schwertmannite precipitated from supersaturated solutions mainly owing to the oxidation of fe ii to fe iii and transformed with time into goethite and jarosite in a few hours schwertmannite precipitation removed more than half of the arsenic load from solution whereas the concentration of divalent trace metals zn cu pb cd ni and co remained almost unchanged in the laboratory natural schwertmannite was kept in contact with its coexisting acid water in a flask with a solid liquid mass ratio of 1 5 for 353 days during this time the ph of the solution dropped from 3 07 to 1 74 and the concentrations of sulfate and fe increased during the first 164 days schwertmannite transformed into goethite plus h3o jarosite but subsequently goethite was the only mineral to form some of the trace elements such as al cu pb and as were depleted in solution during the first stage as schwertmannite transformed into goethite plus h3o jarosite on the contrary the transformation of schwertmannite to goethite with no jarosite during the second stage released al cu and as to the solution despite the variation in their concentrations in solution approximately 80 of the total al and cu inventories and more than 99 as and pb remained in the solid phase throughout the entire aging process

the candelaria punta del cobre iron oxide cu au zn ag deposits chile several iron oxide rich cu au zn ag deposits define an approximately 5 km wide and at least 20 km long belt along the eastern margin of the coastal batholith near copiapo chile this belt includes the large candelaria mine and a group of middle and small sized mines in the punta del cobre district which is located about 3 km northeast of the candelaria deposit estimated geologic resources of the belt are on the order of 700 to 800 million metric tons mt at 1 0 percent cu the ore occurs in veins breccia and stringer bodies and in replacement bodies that are roughly concordant to bedding the orebodies are hosted mainly by volcanic and volcaniclastic rocks of the punta del cobre formation and in places also occur in volcaniclastic intercalations in the lower part of the overlying early cretaceous chanarcillo group most of the larger orebodies in the belt are located where northwest trending brittle faults intersect the contact between massive volcanic and volcaniclastic rocks these northwest faults and a major northeast trending ductile shear zone control portions of the ore of the candelaria deposit chalcopyrite is the only hypogene cu mineral the cu au ore is characterized by abundant magnetite and or hematite and by locally elevated concentrations of ag zn mo and light rare earth elements the ore is hosted mainly in zones with biotite potassium feldspar calcic amphibole epidote alteration at candelaria in the punta del cobre district ore in the deeper parts of the deposits is similarly associated whereas at shallow levels it occurs in zones of biotite potassium feldspar or albite chlorite calcite alteration mineralization at candelaria punta del cobre took place under relatively oxidized conditions manifested by the formation of specular hematite in parts of the district the pseudomorphic replacement of early specular hematite by magnetite during the main iron oxide formation marks a shift toward more reduced conditions or higher temperatures the bulk of the magnetite probably formed at temperatures of about 500 to 600 c the main sulfide stage followed with formation of pyrite and chalcopyrite at temperatures of 470 to 328 c subsequent martitization of the magnetite points to a temperature decrease cooling of the hydrothermal system is also indicated by the homogenization temperatures of 236 c of saline fluid inclusions in late stage calcite oxygen isotope combined with microthermometric data suggest that magmatic fluids or nonmagmatic fluids equilibrated with magmatic silicates were dominant during the main copper mineralization relatively light oxygen isotope signatures of fluids in equilibrium with late calcite suggest mixing with a nonmagmatic fluid e g basinal brines or meteoric waters during the late stages of hydrothermal activity sulfur isotope ratios of chalcopyrite pyrite pyrrhotite and sphalerite from the bronce candelaria las pintadas santos and socavon rampa deposits range from 34scdt values of 0 7 to 3 1 per mil this narrow range of sulfur isotope ratios near 0 per mil is consistent with sulfur of magmatic origin anhydrite from the candelaria mine paragenetically overlaps with chalcopyrite fluid inclusions in this anhydrite homogenize between 340 and 470 c and it has 34scdt values between 14 5 and 17 5 per mil a sulfate sulfide value of 13 4 per mil for a sample with coexisting anhydrite and chalcopyrite is consistent with sulfide sulfate fractionation at temperatures on the order of 400 c ore lead isotope signatures are homogeneous and similar to those of least altered volcanic host rocks and nearby intrusive rocks radiometric ages including new 40ar 39ar ages for hydrothermal alteration at candelaria point to a main cu au mineralization event at candelaria punta del cobre at around 115 ma the ages indicate that ore formation was broadly coeval with batholithic granitoid intrusions and with regional uplift they further imply that the cu au zn ag deposits formed at shallow crustal levels 3 km the stable isotope data the presence of previously reported hypersaline co2 rich fluid inclusions in the main cu ore stage and saline fluid inclusions in late stage calcite the oxidized character of the first ore fluid pulses and the mineralization age coeval with nearby intrusive activity are consistent with but not unequivocally evidence of magmatic fluid contribution into the hydrothermal system

vertical distribution and historical loss estimation of heavy metals in an abandoned tailings pond at htm copper mine northeastern china in the tailings pond of the hongtou mountain htm copper mine in northeastern china four sampling points were set at intervals of 80 m along the discharge direction of the tailings slurry to investigate the vertical distribution characteristics of heavy metals in shallow layer 0 5 m tailings in addition 18 sampling points were set by a grid method 50 m 50 m to estimate the historical loss amount of contaminants from the surface layer 0 1 2 m of the htm tailings pond tailings samples were taken at every 0 2 m and the ph value the total content and acid soluble fraction of heavy metals and chemical compositions were determined following the standard methods the results showed that the ph values of tailings ranged from 3 01 to 8 11 which increased with depths from 0 to 2 2 m and varied between ph values of 7 0 and 7 5 in 2 2 5 m cu zn cd and s were the major contaminants in the tailings the total cu content was higher at the downstream sampling points near the dam zn and cd were higher at the upstream sampling points near the discharge three distinct zones oxidised zone cemented layer and unoxidised zone were found in the htm tailings pond the depth of the oxidised zone was 0 4 m and the elements in the oxidised tailings were obviously lower due to the sulphides oxidation and acid mine drainage cu was enriched in the cemented layer and the cu content reached values between 1200 and 3000 mg kg which were 1 5 3 times higher than the average value zn cd ni and fe were also slightly elevated in the cemented layer below the groundwater table the acid soluble fraction of cu zn and cd was relatively stable at a lower level and showed insignificant variations as the cemented layer and groundwater could efficiently prevent the oxidation process the amount of cu zn and cd leaving the tailings pond with drainage water was 8 08 21 60 and 72 93 respectively of the amount released from oxidation most of the cu released from oxidation was retained in the cemented layer the total mass of s zn and cd released from the tailings to surrounding ecosystems was estimated approximately 762 75 t 6997 5 and 86 06 kg respectively in the last 20 years

experimental heating and kinetic models of source rocks comparison of different methods abstract closed system isothermal micro pyrolysis has been carried out for nine upper jurassic source rocks from the norwegian shelf supplemented by hydrous pyrolysis experiments and open system pyromat kinetic determinations in all investigated cases open system kinetics is able to model the residual potential derived from s2 but not the respective low temperature closed system isothermal experiments the relatively detailed micro pyrolysis generation patterns obtained allow us to differentiate between primary generation and secondary cracking of different carbon number classes of hydrocarbons formation of non hydrocarbons or hydrocarbon sinks in residues can be inferred from these patterns comparison of results from low and high temperature experiments suggests that the potential of a source rock may vary according to heating history discrepancies between high and low temperature experiments may be explained in terms of competing reaction pathways these may constitute a main source of uncertainty when extrapolating bulk kinetic models into geological conditions

modeling the effect of stratification on cemented layer formation in sulfide bearing mine tailings abstract reactive transport simulations have been applied to investigate possible effects of stratification on the potential of sulfide bearing mine tailings to form protective cemented layers the simulations are based on characteristic strata found at a german tailings site including sulfide enriched heavy mineral layers mica enriched silt layers and homogeneously mixed layers the simulated secondary phases jarosite gypsum amorphous ferric arsenate amorphous fe hydroxide alunite amorphous silica and kaolinite are similar to those observed in the field using scanning electron microscope analyses of cemented layers it has been observed that the pore area becomes disconnected if the porosity is decreased to values below 15 which would indicate a strong decrease in permeability stratification was found to play a crucial role in cemented layer formation cemented layers are absent or insignificant in systems with a homogeneous distribution of fe bearing sulfides they are extensively developed in systems with a an arsenopyrite rich layer or b a mica enriched layer situated immediately below an fe sulfide enriched layer the modeling results have clearly demonstrated that the key processes operating in scenario a are very different from the key processes in scenario b in scenario a the oxidation of arsenopyrite is followed by the precipitation of amorphous ferric arsenate which can be solely responsible for significant pore reduction in scenario b the presence of a large amount of reactive aluminosilicates e g biotite and ca bearing plagioclase immediately below the fe sulfide rich layer appears to be crucial key processes are extensive formation of acid rock drainage ard followed by enhanced ph driven weathering of aluminosilicates resulting in the accumulation of secondary phases directly below the fe sulfide rich layer in both scenarios a cemented layer is formed that effectively retards the further downward movement of the oxidation front the presented details on the role of stratification in the formation of cemented layers could be considered in the construction of mining heaps as a possible measure to stimulate natural attenuation

geochemical distribution of arsenic cadmium lead and zinc in river sediments affected by tailings in zimapan a historical polymetalic mining zone of mexico in the historical mining zone of zimapan mexico unprotected tailings deposits are supplying contaminants to the local fluvial system this research was conducted to assess the environmental hazard of these wastes and river sediments by determining the input transport and seasonal variability of arsenic cadmium lead and zinc and their speciation by an operationally defined scheme of decreasing lability f1 fraction soluble in deionized water f2 associated to carbonates f3 oxides and hydroxides of iron f4 sulfides and organic matter f5 residual higher total concentrations of cd pb and zn were present in sediments in the dry season regarding the rainy season in the dry season as and pb were principally associated with the more stable f3 and f5 fractions whereas cd was in f2 and f5 and zn in f3 f2 and f5 in the rainy season the association was mainly f3 for as while f2 and f3 contained most cd pb and zn this fractionation indicates that the environmental hazard of cd pb and zn enhances upon a ph decrease due to their proportion in the carbonatic fraction and shows a mobility increase during the rainy season

geochemical characterization evolution and source of a mesozoic accretionary wedge the torlesse terrane new zealand whole rock major and trace element compositions of quartzofeldspathic permian cretaceous sandstones of the torlesse terrane new zealand display progressive changes which compare well with published petrographic data chemical indices in three permian early late triassic rakaia subterrane petrofacies show small contrasts as do the modes reflecting original source compositions a late triassic rakaia petrofacies displays sharp increases in sio 2 al 2 o 3 k 2 o na 2 o th sc la sc ce sc la n y n and decreases in ti zr and v la consistent with partial cannibalistic recycling and a small influx of lithic volcanic detritus in the post collisional late jurassic early cretaceous pahau subterrane sio 2 al 2 o 3 remains high but other indices decrease to levels seen in the permian due to recycling of the earlier rakaia petrofacies and influx of 10 30 mafic intermediate volcaniclastic detritus derived from inboard volcanogenic terranes the results are confirmed by additional suites including mudstones which cover a larger area but also show that some spatial variation occurs within the terrane as a whole whole rock data and chemical index of alteration indices indicate that the torlesse was derived from a relatively unweathered source with granodioritic bulk composition comparisons with data from a proposed rakaia source in the new england and hodgkinson orogens of eastern australia suggest that the observed chemical and modal compositions cannot be simply derived from that area as presently exposed

a mineralogical and geochemical study of element mobility in sulfide mine tailings of fe oxide cu au deposits from the punta del cobre belt northern chile two flotation tailings sites ojancos and p cerda from the fe oxide cu au punta del cobre belt south of copiapo atacama desert northern chile are geochemically largely using sequential extractions and mineralogically compared main ore minerals are pyrite magnetite and or hematite and chalcopyrite gangue is dominantly calcite with minor quartz the host silicate assemblage is largely controlled by hydrothermal alteration and consists of variable amounts of the following minerals k feldspar ca amphibole biotite sericite chlorite tourmaline epidote quartz in this study both the ojancos and the p cerda tailings were deposited in valley dam impoundments and when they were filled new tailings were deposited upstream as a result high quantities of seepage migrated downstream into the older tailings impoundment at ojancos the recent upstream tailings have excess of acid potential 7 1 wt calcite and 3 5 wt pyrite whereas the older downstream tailings are characterized by alternations of several meter thick intervals with high neutralizing potential about 40 wt calcite and 2 wt pyrite and intervals with high acid potential about 3 wt calcite and 4 wt pyrite acid mine drainage amd with the precipitation of schwertmannite ph 3 15 and chalcoalumite ph 4 9 flows out at the interface between the uphill and downstream tailings strong downstream element transport is taking place and contributes to the formation of the cementation zone mainly gypsum ferrihydrite and goethite and locally jarosite in the older downstream impoundment the cementation zone ph 4 shows strong enrichment of heavy metals e g up to 6800 ppm cu 680 ppm zn 1100 ppm as mainly adsorbed and as secondary sulfides e g covellite in contrast at the p cerda tailings impoundment carbonates are homogeneously distributed and the overall neutralization potential exceeds the acid potential average of about 10 wt calcite and up to 2 5 wt pyrite the up to 5 m thick oxidation zones paste ph 6 9 8 3 at p cerda are characterized by interlayering of coarser dark gray unoxidized layers with fine grained fe iii hydroxide rich ochre to red brown colored horizons the hyperarid climate dries out first the coarse sulfide rich horizons of the tailings and limits so the oxidation which is restricted to the fine grained due to their higher moisture retention capacity however results indicate that during operation an important element transfer from the younger upstream tailings to the older downstream tailings impoundment took place possibly by sorptive transport at ferric polymers or colloids in the form of neutral mine drainage nmd this would explain the metal enrichments in the cementation zone which are mainly associated to the exchangeable fraction and not as secondary sulfides this results in both cases in ojancos mainly as amd and in p cerda mainly as nmd in fe iii input as ferric cation as ferric polymer or co3 complexes to the downstream impoundment this constitutes a very effective acid potential transfer to the older downstream material because oxidation via input of external fe iii produces 16 mol of protons per mol fes2 i e eight times more than via oxidation with oxygen in addition the created acidity favors dissolution of the abundant fe oxides magnetite and hematite of this ore deposit type providing so additional fe iii for sulfide oxidation

composition of modern deep sea sands from arc related basins summary petrographic and chemical examination of modern deep sea sands shows a clear distinction between active and passive plate tectonic settings among active settings sands from forearc basins of island arcs and basins from strike slip continental margins can be distinguished but those from other arc related settings overlap considerably in composition in particular sands from continental margin subduction zones and those from the backarc of island arcs appear to be indistinguishable chemically arc related sands are very close in composition to ancient greywacke sandstones for instance sodium almost always exceeds potassium thus it is not necessary for sodium to be added to sands diagenetically to make greywackes as has been suggested the influence of tectonics on the composition of sandstones has long been a central feature of sandstone petrology the geosynclinal model of global tectonics stimulated much thought on this subject probably the best known ideas are those of krynine e g 1942 subsequently such research declined but the plate model for global tectonics has produced a new wave of interest e g crook 1974 schwab 1975 potter 1978 dickinson suczek 1979 much of this work has relied on data from ancient sediments where diagenetic changes and difficulty in de ciphering the tectonic setting limit the useful ness of the conclusions much more work is needed on recent sediments to establish a base line against which ancient sediments can be compared we have previously reported valloni maynard 1981 the results of our work on the petrography of a set of recent deep sea sands from piston cores in this paper we shall com pare this petrographic information with bulk chemistry and attempt to relate these to tecto nics in arc related settings

origin of the torlesse terrane and coeval rocks south island new zealand the carboniferous to lower cretaceous torlesse terrane and haast schist derivatives constitute the major part of the complexly deformed facies of the eastern province of new zealand strata consist mainly of quartzofeldspathic graywacke and mudstone intercalated with minor but widely distributed conglomerate and volcanics with associated chert and limestone clastic rocks were deposited largely by sediment gravity flow mechanisms in a deep marine environment also present are a few highly fossiliferous shallow marine and terrestrial deposits of limited areal extent which rest unconformably on or in fault contact with torlesse flysch several periods of deformation are recognized and melange is present on both local and regional scales metamorphism ranges from zeolite to greenschist facies the bulk of the rocks fall into five areally extensive and mutually exclusive fossil zones of the following ages permian atomodesma middle triassic early late triassic torlessia late triassic monotis and late jurassic early cretaceous contacts between major fossil zones are mainly tectonic petrographic analysis permits subdivision of torlesse sandstones into five major petrofacies that correspond in age to the five major fossil zones the sandstone petrofacies mainly arkosic together with the composition of conglomerate clasts mainly indurated torlesse rocks indicate that the source terrane was a continental volcano plutonic arc probably part of gondwanaland coupled with autocannibalistic reworking of older uplifted torlesse rocks in contrast to the quartzofeldspathic nature of the torlesse coeval sedimentary rocks of the eastern province are volcanogenic they are thought to represent related forearc basin maitai murihiku terranes and trench complex caples terrane deposits derived from a volcanic island arc brook street terrane three petrofacies are established for maitai murihiku and caples sandstones the petrofacies indicate a common evolving immature to submature volcanic island arc source for these terranes a reconstruction of new zealand s eastern and western provinces is proposed in permian and triassic times the torlesse was deposited in trench slope or borderland basins along a trench transform margin fronting a continental volcano plutonic arc source western province gondwanaland deposition was spasmodic but voluminous and was accompanied by concurrent deformation and accretion resulting in parallel belts of torlesse rock younging outward from the gondwanaland margin at the same time the brook street terrane volcanic arc and associated terranes were forming to the west of the torlesse site separated from gondwanaland by a marginal sea in latest triassic or early jurassic times the torlesse was rafted into the volcanic arc system via transform faulting approximately parallel to the gondwana margin the collision event resulted in tectonic thickening of torlesse and caples rocks at the plate interface and metamorphism to haast schist the source was then dominated by older partly metamorphosed torlesse terrane newly uplifted along the collision front closing of the marginal sea behind the brook street terrane in late jurassic early cretaceous times resulted in juxtapositioning with the western province gondwanaland along the median tectonic line

the role of prokaryotes in supergene alteration of submarine hydrothermal sulfides we combine mineralogical stable isotope and organic biomarker data to understand the role of prokaryote activity in supergene reactions within submarine hydrothermal sulfidic sediments data are presented for two adjacent cores from the periphery of the inactive alvin hydrothermal mound the limit of oxygenated seawater penetration into the sulfidic sediments is expressed as a sharp peak in solid phase cu atacamite and secondary cu sulfides associated with supergene alteration of the sulfide pile total prokaryote numbers are low throughout the upper few metres of sediment relative to published data for deep sea sites however there is a statistically significant enrichment of prokaryote numbers at the redox front that coincides with abundant fe oxide filaments and a unique distribution of microbial biomarkers the dominance of quaternary branched alkanes in the oxidized transition zone immediately above the redox front and their absence below suggests a significant role of the source organisms in iron or sulfide oxidation under the more circumneutral conditions associated with the redox transition zone the morphology of the fe oxide filaments preserved within late stage silica and gypsum mineralization is consistent with a biogenic origin of the filaments gypsum sulfur isotopes are in equilibrium with fluids that are derived from quantitative sulfide oxidation and gypsum nucleation is inferred to be biologically induced these new data suggest that supergene alteration of sulfidic sediments generates sharp redox and ph gradients that stimulate prokaryotic activity in particular iron and sulfide oxidisers which in turn govern the distribution of secondary mineral phases and the abundance of redox sensitive trace metals

coupled thermal hydraulic and geochemical evolution of pyritic tailings in unsaturated column experiments the evolution of pore water and the composition of solid phases in the vadose zone of pyritic tailings was studied by means of unsaturated column experiments several columns of water saturated mine tailings were dried during 125 days under controlled laboratory conditions the columns were dismantled at four successive drying stages and the evolution of pore water mineralogy water content and temperature was characterized sulfide and aluminosilicate minerals present in the waste dissolved releasing sulfate and other solutes mainly fe zn cu al mg and ca to the pore water evaporation caused a crust of efflorescent water soluble sulfates to develop over the complete top surface of the columns and into the pores of the underlying waste material this crust which has also been identified in the field changed the hydraulic properties of the tailings and produced a decrease in the evaporation rate of the columns moreover these water soluble precipitates mainly rozenite szomolnokite halotrichite hexahydrite mirabilite and gypsum acted as temporary sinks for cd pb co and ni which could be released to the surface run off or the groundwaters during rainfall events under field conditions pore water evolution was determined not only by geochemical processes dissolution of sulfides and aluminosilicates precipitation of secondary phases but also by thermal and hydraulic processes progressive dilution was observed in the lower part of the columns dilution was caused by the thermally driven vapor flux from the top of the column to its colder bottom and subsequent condensation therein this process which may also occur in tailings under sub arid climate played a key role on the evolution of pore water with increasing drying

contamination of surface waters by mining wastes in the milluni valley cordillera real bolivia mineralogical and hydrological influences this study is one of very few dealing with mining waste contamination in high altitude tropical latitude areas exploited during the last century geochemical mineralogical and hydrological characterizations of potentially harmful elements phes in surface waters and sediments were performed in the milluni valley main reservoir of water supply of la paz bolivia 4000 m a s l throughout different seasons during 2002 2004 to identify contamination sources and sinks and contamination control parameters phe concentrations greatly exceeded the world health organization water guidelines for human consumption the very acidic conditions which resulted from the oxidation of sulfide minerals in mining waste favoured the enrichment of dissolved phes cd zn as cu ni pb sn in surface waters downstream from the mine stream and lake sediments mining waste and bedrock showed the highest phe content in the mining area with the exception of fe the phes were derived from specific minerals fe pyrite zn cd sphalerite as fe arsenopyrite cu fe chalcopyrite pb galena sn cassiterite but the mining was responsible for phes availability most of the phes were extremely mobile as fe pb cd zn cu sn in the mining wastes and the sediments downstream from the mine ph and oxyhydroxides mainly explained the contrasted availability of zn mostly in labile fractions and as associated with fe oxyhydroxides unexpectedly pb zn as and fe were significantly attenuated by organic matter in acidic lake sediments hydrological conditions highly influenced the behaviours of major elements and phes during wet seasons major elements were diluted by meteoric waters whereas phes increased due to the dissolution of sulfides and unstable tertiary minerals that formed during dry seasons this is particularly obvious at the beginning of the wet season and contributes to flushes of element transport downstream the high altitude of the study area compensates for the tropical latitude rendering the geochemical behaviour of contaminants similar to that of temperate and cold regions these results might be representative of geochemical processes in ore deposits located in the high andes plateau and of their influence on phe concentrations within the upper amazon basin although mining activities in this region stopped 10 years ago the impact of mining waste on water quality remains a serious environmental problem

arsenic and metal mobility from au mine tailings in rodalquilar almeria se spain in the old mining area of rodalquilar mine wastes soil and sediments were characterized and the results revealed high concentration of au ag as bi cu fe mn pb se sb and zn in tailings and sediments the contaminant of greatest environmental concern is as the mean concentration in the tailings was 679 9 and 345 mg kg in the sediments of playazo creek the groundwater samples from the alluvial aquifer showed high concentration of al as cd fe hg mn ni pb se sb and zn and very high concentration of chloride and sulfate which were above the concentration defined in the european standards for drinking water the presence of as in groundwater may be caused by the oxidation of arsenian pyrite the possible as desorption from goethite and ferrihydrite and the jarosite dissolution groundwater concentrations of cd fe mn and possibly cu were associated with low values of eh indicating the possible dissolution of oxy hydroxides of fe and mn the mobility of metals in the column experiments show the release of al fe mn cr cu ni v and zn in significant concentrations but below the detected values in groundwater however as cd sb se pb and au are generally mobilized in concentrations above the detected values in groundwater the possible mass transfer processes that could explain the presence of the contaminants in the aquifer and the leachates was simulated with the phreeqc numerical code and revealed the possible dissolution of the following mineral phases jarosite natrojarosite arsenian pyrite alunite chlorite kaolinite and calcite

distribution patterns of contaminants in the mogale gold tailing dam a case study from south africa this study evaluates the geochemical and mineralogical characterisation of weathering layers associated with the mogale tailing dam in the randfontein cluster witwatersrand basin south africa in the tailing dam it is observed that high hematite fe2o3 contents separate the ferruginous from the rest layers also the oxidised layers with high quartz sio2 contents compositionally differ from the underlying capillary zone grey and ferruginous layers likewise a combination of gypsum contents mno cao tot s versus pyrophyllite muscovite al2o3 and k2o distinguishes the lower grey from the upper grey layer which corresponds to the saturated and capillary zones respectively similarly the amount of ree and most trace elements depleted in the oxidised layers is compared to the underlying layers factor analysis of this variation in layers related element distribution to the spatial patterns of pyrite gypsum hematite and jarosite furthermore analysis of the mass balance revealed an estimated net loss of between 23 and 123 ppm for uranium zinc nickel and arsenic right from the inception of the tailing dam 50 years ago a loss of between 1 5 1 8 and 2 8 2 9 is also estimated for total sulphur and aluminium respectively these results underpin the sources and patterns of mobilisation of elements in the weathering zones as a major step towards the development of a predictive model for mitigation of amd in the region

hydrochemistry mineralogy and chemical fractionation of mine and processing wastes associated with porphyry copper mines a case study from the sarcheshmeh mine se iran abstract the sarcheshmeh is one of the largest oligo miocene porphyry cu deposits in the world comparative hydrochemical mineralogical and chemical fractionation associated with mining efflorescence salts and processing wastes of this mine are discussed hydrochemical results showed that rock waste dumps reject wastes and old impoundments of tailings are the main sources of acid mine drainage waters amd that contain potentially toxic metals such as cd co cu mn ni and zn as well as al episodic fluxes of highly contaminated acidic waters were produced in a tailings dam over a short period of time secondary soluble minerals provide important controls on the quality of amd produced especially in old dry tailings impoundments secondary sulfate minerals such as gypsum magnesiocopiapite hydronium jarosite kornelite and coquimbite were found in rock waste drainages and in old weathered reject wastes highly soluble secondary minerals such as gypsum eriochalcite and bonattite are also observed in an evaporative layer on old tailings impoundments chemical fractionation patterns of potentially toxic elements showed that the geochemical behavior of metals is primarily controlled by the mineralogical composition of waste samples elements such as co cr cu mn ni and zn are readily released into the water soluble fraction from efflorescence salts associated with rock waste drainages as well as from the evaporative layer of old tailings potentially toxic elements such as as mo and pb are principally adsorbed or co precipitated with amorphous and crystalline fe oxides but they may also be associated with oxidizing primary sulfides and residual fractions following the development of the dammed tailings pond the secondary minerals were dissolved producing acidic waters contaminated by al 154 mg l 1 cu 150 mg l 1 cd 0 31 m gl 1 co 2 13 mg l 1 mn 73 7 mg l 1 ni 1 74 mg l 1 zn 20 3 mg l 1 and cl 1690 mg l 1 therefore the potential use of recycled water from the sarcheshmenh dammed tailings pond is diminished by the presence of corrosive ions like cl in highly acidic fluids that promote corrosion of pipes and pumps in the water recycling system

mineralogical and geochemical investigations of pyrite rich mine waste from a kyanite mine in central virginia with comments on recycling a pyrite rich waste stream is one of three types generated from a kyanite mine in central virginia near the town of dillwyn buckingham county currently ore consists of approximately 3 pyrite waste and an estimated 382 000 tons of this waste stream has been generated over the past 60 years the mineralogy of the waste stream consists of variable amounts of pyrite 70 99 talc 1 20 quartz 1 10 kyanite 0 5 5 with minor or trace amounts of magnetite hematite galena anorthite and rare earth phosphate energy dispersive spectroscopy analysis indicates that talc has minor amounts of al up to 1 57 wt and fe up to 4 29 wt and pyrite grains have no impurities above detection limit of approximately 0 1 wt bulk chemical analysis of selected elements using inductively coupled plasma mass spectrometry analysis indicate that zn 28 82 367 71 ppm as 8 94 18 26 ppm se 44 62 64 50 ppm cd 0 19 1 03 ppm hg 0 87 35 91 ppm and pb 65 10 189 66 ppm occur at levels of some environmental concern au and ag concentrations are negligible currently the waste stream is well managed and sold but for a low price talc is of sufficient quality to be of interest for recycling but the estimated 540 tons generated per year is not a suitable quantity to be economically viable currently the waste stream is not viable for recycling for higher monetary value however the characteristics of the pyrite may enable such recycling in the future for solar energy technologies this and other associated waste streams show long term promise for integrated recycling and may play important economic roles in an economically disadvantaged region

spatial variability of arsenic in some iron rich deposits generated by acid mine drainage abstract potential contamination of rivers by trace elements can be controlled among others by the precipitation of oxyhydroxides the streambed of the studied area located in la ch taigneraie district lot river basin france is characterised by iron rich ochreous deposits acidic ph 2 7 4 8 and so 4 mg waters beyond the acid mine drainage the presence of as both in the dissolved fraction and in the deposits is also a problem upstream at the gallery outlet as concentrations are high as max 2 6 mol l and up to 5 wt locally respectively in the dissolved and in the solid fractions downstream as concentrations decrease below 0 1 mol l in the dissolved fraction and to 1327 mg kg in the solid fraction this natural attenuation is related to the as retention within ochreous precipitates amorphous to poorly crystalline fe oxyhydroxides schwertmannite and goethite which have great affinities for this metalloid upstream schwertmannite is dominant while downstream goethite becomes the main mineral the transformation of schwertmannite into goethite is observed in the upstream deposits as schwertmannite is unstable relative to goethite furthermore thermodynamic calculations indicate that the downstream goethite is not able to precipitate in situ according to the water chemistry goethite mainly results from the transformation of schwertmannite and its solid transport downstream moreover as highlighted by leaching experiments carried out on the ochreous precipitates this transformation does not seem to affect the as retention in solids as no release of as was observed in the solution arsenic may either be strongly trapped by co precipitation in the present minerals or it may be quickly released and re adsorbed on the precipitate surface

geochemical petrographic and grain size variations within single turbidite beds pronounced changes in chemical composition were detected upwards within single turbidite beds with sio2 contents deceasing by as much as 20 all other major elements and eighteen trace elements increase in abundance upwards enrichment factors from bed base to top range from 1 2 na2o to 5 7 cu these changes are related to textural and mineralogical grading that in turn were the result of turbidity current action before and during the deposition of the bed we found only slight changes in the modal petrographic composition of the sandstone fractions although this technique is operator dependent and only semi quantitative in nature chemical analysis appears to be a more sensitive more rapid and less subjective method of determining provenance and the compositional contrasts within beds chemical anomalies produced by dilution effects from quartz overgrowths and intrabasinal material however show the need for utilisation of a combination of techniques and for an appreciation of the interdependence of texture framework modes and bulk chemistry the chemical variations we detect in single beds also reflect the variation in a suite of representative samples collected from within a confined several km2 geographic area hence either sampling over a given area or specific sampling of individual beds provided that the bed is typical of the succession as a whole can be used to determine the compositional variations within a succession as a whole

the new england batholith eastern australia geochemical variations in time and space the new england batholith australia is part of the upper paleozoic new england fold belt with most plutons intruded into the deformed trench complex metasedimetary rocks in the southeast part of the fold belt the batholith was emplaced in two major periods of plutonism the first during the upper carboniferous and the second during the upper permian and triassic with a major phase of metamorphism and deformation including westward overthrusting of the trench complex sedimentary rocks between the two periods on the basis of petrography geochemistry and isotopic characteristics the granitoids of the batholith are subdivided into five named intrusive suites and a group of leucoadamellites the differences between the six groups are considered to reflect differences in their source rock types the carboniferous granitoids are peraluminous s type and are divided into the bundarra plutonic suite a belt of very coarse grained adamellites with cordierite garnet and the hillgrove plutonic suite a belt of biotite rich garnet deformed adamellites and granodiorites both suites have 18o greater than 10 negative 34s 87sr 86sr initial ratios about 0 706 are ilmenite bearing and have low feo3 ratios the bundarra plutonic suite however is consistently sio2 rich greater than 70 contains cordierite and has higher 18o than the hillgrove plutonic suite the two s type suites are inferred to have formed by partial melting of the deepest parts of a wedge of trench complex sedimentary rocks oceanwards of an andean volcanic chain to the west analagous to the lower tertiary s type plutons of the sanak baranof plutonic belt of southern alaska of the remaining four groups of plutons emplaced during the upper permian and triassic two are metaluminous i type granitoids one the clarence river plutonic suite new name a group of k poor granodiorites and tonalites with low 87sr 86sr initial ratios average 0 7035 and the other the moonbi plutonic suite a group of k rich adamellites with low 87sr 86sr initial ratios average 0 7045 18o less than 10 and 34s positive the clarence river plutonic suite is inferred to have formed from the partial melting of a large ion lithophile element poor gabbro source region and the moonbi plutonic suite from a large ion lithophile element rich shoshonite source region a third group the uralla plutonic suite is less metaluminous has higher 87sr 86sr initial ratios average 0 706 18o only just less than 10 and negative 34s and is considered to have formed in a region containing a physical mixture of metaluminous and peraluminous source rocks gabbro and metasedimentary rocks plutons of the fourth group are leucoadamellites largely emplaced after the other suites with low 18o indicating an i type source it is argued that this group has resulted from low degrees of dry partial metling of an i type source region that had undergone an earlier melting event these four groups of plutons are largely confined to a narrow belt parallel to but 100 km west of the present rifted margin of australia their origin may be related to crustal thickening attendant on the overthrusting that occurred early in the permian and or a temperature increase in the lower crust due to the recovery of normal continental geotherms following the cessation of subduction

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

influence of climate mineralogy and mineral processing on the weathering behaviour within two low sulfide high carbonate gold mine tailings in the eastern desert of egypt despite its importance within environmental management strategies little concern is shown to sulfide oxidation and or hardpan formation at neutral ph where dry condition prevails two gold mine tailings in egypt el sid and barramiya were studied for their geochemical mineralogical properties and climate influence on hardpan formation the tailings are characterised by homogeneous silt sized sediments 42 have high carbonate predominantly as calcite for el sid and dolomite ankerite for barramiya and low sulfide contents chiefly as pyrite galena and sphalerite for el sid and arsenopyrite pyrite for barramiya el sid is characterised by high average concentrations of pb 2 758 mg kg and zn 2 314 mg kg its lower part dominated by mafics overlaid by granitoids barramiya has higher as average 2 836 mg kg content and represents a mixture of mica schists mafics ultramafics during field investigations no hardpans were identified only bassanite and gypsum were found at the surface of el sid tailings forming thin layers and desiccation crack fillings column experiments showed a thin crust consisting of gypsum halite and sodium sulfate formed at the top of the column of el sid tailings after 2 weeks this was not recognized in the column from barramiya the homogenous thickened tailings deposition in both areas did not favour hardpan formation since the critical amounts of reacting sulfides were never achieved in individual lamina due to missing mineral grain size fractionation the high temperature low water availability characteristic for desert climate regions did not allow significant sulfides oxidation therefore both tailings will suffer from continuous erosion and spreading out of contaminants to the environment for a prolonged period of time by sporadic flash floods

mineralogical changes and distribution of heavy metals caused by the weathering of hydrothermally altered pyrite rich andesite the weathering of pyrite rich andesite in the southeastern part of korea has led to acid rock drainage creating severe environmental problems in the region in this study the mineral compositions and geochemical mobility of heavy metals in the bedrock in addition to the weathering products are investigated samples of bedrock and weathering products were collected from two sites in the yangsan area site 2 shows considerably more weathering than site 1 due to the longer duration of weathering the mineral compositions show that the bedrock at site 2 was more heavily altered by hydrothermal activity the weathering products at site 2 contain jarosite and goethite with lower ph values than site 1 in which the samples are buffered by calcite this indicates that the mineral compositions and ph values of the weathering products at the two sites are influenced by the primary mineral compositions of the bedrock and the duration of weathering with the exception of pb the concentrations of heavy metals at site 1 are higher than those at site 2 probably due to higher concentrations in the bedrock moreover the labile and acid soluble fractions which can be more readily released into the environment are higher at site 1 mainly due to the shorter duration of weathering accordingly the weathering process at site 1 carries more potential hazards to the environment than that at site 2 however chemical weathering is locally impeded by calcite buffering at site 1 although the concentrations of heavy metals at site 2 are lower than those at site 1 they are being continuously released due to the lower ph and longer and more and extensive weathering

geochemical mineralogical and microbiological characterization of a sulphide bearing carbonate rich gold mine tailings impoundment joutel quebec abstract the results of an integrated geochemical and mineralogical study conducted at the agnico eagle gold mine tailings impoundment joutel quebec are correlated with bacterial populations determined from an enumeration of 3 groups of thiobacilli the tailings were determined to contain approximately 5 wt sulphide s predominantly as pyrite and up to 30 wt carbonate minerals chiefly as dolomite ankerite and siderite the objective of the study was to evaluate the potential for the development of acidic drainage and dissolved metal migration in carbonate rich tailings impoundments and to compare the results of the geochemical and microbiological characterization of the tailings sulphide oxidation reactions have proceeded to a depth of 20 100 cm below the tailings surface pyrrhotite consistently shows more alteration than pyrite and arsenopyrite pyrrhotite is altered mainly through the replacement by goethite the most abundant thiobacilli are neutrophilic bacteria of the thiobacillus thioparus type the maximum most probable number values for these bacteria occur 20 40 cm below the tailings surface a depth that coincides with the disappearance of oxide coatings this observation coupled with the sharp decline in gas phase o 2 concentration suggests that rapid bacterially mediated s oxidation is occurring at this depth the pore water ph throughout the tailings varies between 6 5 and 8 5 no low ph waters were observed in the impoundment these neutral ph conditions are attributed to the effect of acid consuming carbonate mineral dissolution reactions which are also indicated by increased concentrations of mg and ca and alkalinity in the shallow zone of the tailings as a result of these acid neutralization reactions dissolved metal concentrations are low

geochemical and mineralogical aspects of sulfide mine tailings abstract tailings generated during processing of sulfide ores represent a substantial risk to water resources the oxidation of sulfide minerals within tailings deposits can generate low quality water containing elevated concentrations of so 4 fe and associated metal loid s acid generated during the oxidation of pyrite fes 2 pyrrhotite fe 1 x s and other sulfide minerals is neutralized to varying degrees by the dissolution of carbonate oxy hydroxide and silicate minerals the extent of acid neutralization and therefore pore water ph is a principal control on the mobility of sulfide oxidation products within tailings deposits metals including fe iii cu zn and ni often occur at high concentrations and exhibit greater mobility at low ph characteristic of acid mine drainage amd in contrast hydr oxyanion forming elements including as sb se and mo commonly exhibit greater mobility at circumneutral ph associated with neutral mine drainage nmd these differences in mobility largely result from the ph dependence of mineral precipitation dissolution and sorption desorption reactions cemented layers of secondary oxy hydroxide and hydroxy sulfate minerals referred to as hardpans may promote attenuation of sulfide mineral oxidation products within and below the oxidation zone hardpans may also limit oxygen ingress and pore water migration within sulfide tailings deposits reduction oxidation redox processes are another important control on metal loid mobility within sulfide tailings deposits reductive dissolution or transformation of secondary oxy hydroxide phases can enhance fe mn and as mobility within sulfide tailings production of h 2 s via microbial sulfate reduction may promote attenuation of sulfide oxidation products including fe zn ni and tl via metal sulfide precipitation understanding the dynamics of these interrelated geochemical and mineralogical processes is critical for anticipating and managing water quality associated with sulfide mine tailings

multiphase flow and reactive transport model in vadose tailings weathering processes affecting pyritic wastes may generate huge amounts of acid waters with high concentrations of potentially toxic contaminants acid mine drainage acid mine drainage is mainly produced in the vadose zone in the present study a coupled non isothermal multiphase flow and reactive transport model of the vadose zone of sulfide mine tailings was developed the geochemical model included kinetically controlled reactions for fe ii oxidation and for the dissolution of sulfide and aluminosilicate phases and the pitzer ion interaction model to describe the behavior of the pore water solutions model results were compared with experimental observations in unsaturated column experiments under strongly evaporative conditions similar to arid or semiarid climates evolution trends for temperature water saturation evaporation rates pore water hydrochemistry and mineral phases observed during the drying experiment were adequately reproduced the coupled model reproduced the increase of solute concentrations in the column top and the precipitation of a crust of secondary mineral phases this crust became a barrier for water vapour diffusion to the atmosphere and modified the thermohydraulic behavior of the tailings enhanced downward migration of water vapour and its condensation in this colder end of the column were correctly taken into account by the model which reproduced the dilution observed in the lower part of the column during the experiments

the role of mineralogy on element mobility in two sulfide mine tailings from the iberian pyrite belt sw spain abstract a detailed study of two adjacent mine tailings impoundments comparing mineralogical and geochemical analyses of the solids with geochemical analysis of the pore water and gas was carried out in the monte romero sulfide mining district iberian pyrite belt sw spain since 1978 both facilities have been exposed to weathering in a semi arid climate with dry warm and wet rainy seasons in these impoundments sulfide oxidation releases sulfate and contaminants to the pore water that are transported and concentrated by evaporation in the top surface of the tailings causing precipitation of soluble iron sulfate salts in dry seasons these salts act as temporary sinks for minor elements such as cd co zn ni cu and mn which are again released during rainfall events in wet seasons stored flotation tailings have an average pyrite content of 30 wt although average amounts up to 80 are present in the upper 50 cm of one of the impoundments according to the results of the current study this difference is key to control the oxidation model in both tailings in the impoundment containing 30 wt of pyrite pore water ph increases in wet periods to 3 1 average by rainwater dilution causing supersaturation and precipitation of secondary fe iii phases such as jarosite goethite and schwertmannite consequently this impoundment shows a 20 25 cm thick yellowish oxidation layer in the top part in contrast in the impoundment containing 80 wt of pyrite in the top part extremely acidic pore waters ph

limestone and chert in tectonic blocks from the esk head subterrane south island new zealand the esk head subterrane is a continuous belt generally 10 20 km wide of tectonic melange and broken formation on the south island of new zealand this subterrane separates older and younger parts of the torlesse terrane which is an extensive accretionary prism composed mostly of quartzo feldspathic submarine fan deposits ranging from permian to early cretaceous in age the torlesse is the most pacific ward of several permian and mesozoic accreted terranes in new zealand that record tectonic amalgamation and ultimate accretion against the pacific facing gondwana margin the esk head subterrane of the torlesse is especially informative because it includes within it conspicuous tectonic blocks of submarine basalt and a variety of basalt associated seamount and sea floor limestones and cherty rocks thought to be representative of the subducted plate limestones in tectonic blocks are of late triassic and probably jurassic ages and include 1 submarine cemented pelagic bivalve geopetal packstone grainstone 2 brachiopod bryozoan encrinite and 3 radiolarian pelagic lime mudstone most of the triassic blocks have been dated using conodonts which have remarkably low color alteration index cai values paleogeographic inferences drawn from megafossils bioclasts and radiolarians as well as from carbonate cements indicate deposition of the oceanic sedimentary rocks at paleolatitudes somewhat lower than that of the new zealand part of the gondwana margin but higher than paleoequatorial latitudes these oceanic sediments and their basaltic substrates were evidently emplaced in the torlesse accretionary prism following off scraping from an extensive subducting oceanic plate probably the phoenix plate which was obliquely convergent with the northwest trending gondwana margin during late jurassic and or early cretaceous time

the effect of mineralogy on the mobility of heavy metals in mine tailings a case study in the samsanjeil mine korea this study examined the chemical speciation and mobility of as and heavy metals in a tailings impoundment in samsanjeil mine located in gosung korea as well as the factors affecting them xrd sem and 5 step sequential extraction were used to examine the samples at two sampling sites nn and sn sites the ph of the tailings decreased with increasing depth at the nn site from 7 2 to 2 8 whereas no significant differences were observed at the sn site 8 1 8 8 the samples at the sn site showed a larger amount of calcite than those at the nn site indicating that calcite plays an important role buffering the ph in the study sites jarosite was found only at the lower part of the nn site where calcite was not found the mineralogical observation of jarosite and calcite was also confirmed by sem the concentrations of as and heavy metals in the tailings were as follows cu as zn pb co cr ni cd the total concentrations of ni zn co and cd were higher at the sn site than those at the nn site on the other hand the concentrations of as and cr existing as oxyanions were higher at the nn site which can be explained by the mobility changes of those elements affected by ph variations at the nn site the fractions of heavy metals bound to the fe mn oxides except for as and cr decreased and cu zn and co showed an increasing fraction of exchangeable metals with increasing depth this suggests that the ph and resulting surface charge of minerals such as goethite and jarosite are the dominant factors controlling the chemical speciation of metals these results highlight the importance of mineralogy in controlling the mobility and possible bioavailability of heavy metals in tailings

the importance of colloids for the behavior of uranium isotopes in the low salinity zone of a stable estuary particle mediated removal processes of u isotopes were investigated during spring flood discharge in the low salinity zone lsz up to 3 practical salinity units psu of a stable estuary a shipboard ultrafiltration cross flow filtration cff technique was used to separate particles 0 2 m and colloids between 3000 daltons 3 kd and 0 2 m from ultrafiltered water 3 kd containing dissolved species sediment traps were used to collect sinking material concentration of fe and organic c which are indicators of the major u carrier phases were used to interpret the behavior of 234 u 238 u during estuarine mixing colloids dominated the river water transport of u carrying 90 of the u on entering the estuary colloids accounted for the dominant fraction of u to about a salinity of 1 psu but only a minor fraction 1 psu there is a general correlation between u and salinity in all filtered fractions the 234 u 238 u ratios in different filtered fractions and sinking particles were generally indistinguishable at each station and showed enrichment in 234 u compared with secular equilibrium 234 u 266 567 this clearly shows that all size fractions are dominated by nondetrital u consideration of u isotope systematics across the estuary reveals that substantial u exchange must occur involving larger particles at least to 1 psu and involving colloids at least to 1 5 psu further exchange at higher salinities may also occur as the proportion of u on colloids decreases with increasing salinity this may be due to decreasing colloid concentration and increasing stabilization of uranyl carbonate complexes during mixing in the estuary the results show that although u is a soluble element that shows generally conservative mixing in estuaries removal occurs in the very low salinity zone and this zone represents a significant sink of u variation in composition and concentration of colloidal particles between different estuaries might thus be an important factor for determining the varying behavior of u between estuaries

mobilization of ag heavy metals and eu from the waste deposit of the las herrerias mine almeria se spain we studied the mobility of silver heavy metals and europium in waste from the las herrerias mine in almeria se spain the most abundant primary mineral phases in the mine wastes are hematite hydrohematite barite quartz muscovite anorthite calcite and phillipsite the minor phase consisted of primary minerals including ankerite cinnabar digenite magnesite stannite siderite and jamesonite and secondary minerals such as glauberite szomolnokite thenardite and uklonscovite the soils show high concentrations of ag mean 21 6 mg kg 1 ba mean 2 5 fe mean 114 000 mg kg 1 sb mean 342 5 mg kg 1 pb mean 1 229 8 mg kg 1 zn mean 493 mg kg 1 mn mean 4 321 1 mg kg 1 cd mean 1 2 mg kg 1 and eu mean 4 0 mg kg 1 the column experiments showed mobilization of ag al ba cu cd eu fe mn ni sb pb and zn and the inverse modelling showed that the dissolution of hematite hausmannite pyrolusite and anglesite can largely account for the mobilization of fe mn and pb in the leaching experiment the mobility of silver may be caused by the presence of kongsbergite and chlorargyrite in the waste while the mobility of eu seems to be determined by eu oh 3 which controls the solubility of eu in the ph eh conditions of the experiments the mineralogy ph eh and geochemical composition of the mine wastes may explain the possible mobilization of heavy metals and metalloids however the absence of contaminants in the groundwater may be caused by the carbonate rich environment of host rocks that limits their mobility

post depositional redistribution of trace metals in reservoir sediments of a mining smelting impacted watershed the lot river sw france abstract mining smelting wastes and reservoir sediment cores from the lot river watershed were studied using mineralogical xrd sem eds empa and geochemical redox dynamics selective extractions approaches to characterize the main carrier phases of trace metals these two approaches permitted determining the role of post depositional redistribution processes in sediments and their effects on the fate and mobility of trace metals the mining smelting wastes showed heterogeneous mineral compositions with highly variable contents of trace metals the main trace metal bearing phases include spinels affected by secondary processes silicates and sulfates the results indicate a clear change in the chemical partitioning of trace metals between the reservoir sediments upstream and downstream of the mining smelting activities with the downstream sediments showing a 2 fold to 5 fold greater contribution of the oxidizable fraction this increase was ascribed to stronger post depositional redistribution of trace metals related to intense early diagenetic processes including dissolution of trace metal bearing phases and precipitation of authigenic sulfide phases through organic matter om mineralization this redistribution is due to high inputs derived from mining smelting waste weathering at the water sediment interface of i dissolved so4 promoting more efficient om mineralization and ii highly reactive trace metal bearing particles as a result the main trace metal bearing phases in the downstream sediments are represented by zn and fe sulfides with minor occurrence of detrital zincian spinels sulfates and fe oxyhydroxides sequestration of trace metals in sulfides at depth in reservoir sediments does not represent long term sequestration owing to possible resuspension of anoxic sediments by natural floods and or anthropogenic dredging dam flush events that might promote trace metal mobilization through sulfide oxidation it is estimated that during a major flood event about 870 t of zn 18 t of cd 25 t of pb and 17 t of cu could be mobilized from the downstream reservoir sediments along the lot river by resuspension induced oxidation of sulfide phases these amounts are equivalent to 13 fold cd 6 fold zn 4 fold pb the mean annual inputs of the respective dissolved trace metals into the gironde estuary

mineralogical and geochemical constraints on environmental impacts from waste rock at taojiang mn ore deposit central hunan china the mineralogy and geochemistry of the waste rocks distributed at taojiang mn ore deposit central hunan province china were studied using x ray powder diffraction xrd electron microprobe analysis empa fitted with energy dispersive spectrometer eds and inductively coupled plasma mass spectrum atomic emission spectra icp ms aes with the aim of predicting the environmental impacts of weathering of the waste rocks the mineralogical results from microscope observation and xrd and empa studies show that the waste rock is composed of black shale and minor mn carbonates the oxidation of sulfide minerals such as galena pyrite and chalcopyrite is accompanied by decomposition of mn carbonates and k feldspar during exposure to atmospheric o2 the geochemical characteristics of major rare earth elements ree and trace elements of the waste rocks also show that the waste rock can be divided into black shale and mn carbonate and both of them are currently under chemical weathering the major alkalies and alkaline elements ca mg na k rb sr and cs and major elements fe s and p and heavy metals sc v cr th u sn co ni cu zn pb mo cd sb an tl are being released during weathering the mobility of alkalis and alkaline elements ca mg na k rb sr and cs is controlled by decomposition of mn carbonates the dispersion of cr sc and th u might be related to weathering of k feldspar and the release of the heavy metals co ni cu zn pb mo cd sb and tl is dominated by the breaking of sulfide minerals the ree of the waste rocks and surrounding soils and the spidery distribution patterns of heavy metals in the waste rocks the surrounding soils and the surface waters show that weathering of the waste rocks and bedrock might be the sources of heavy metal contamination for the surrounding soils and surface water system for the mining area this is predicted by the mass balance calculation by using zr as an immobile element therefore it is urgently necessary take measures to treat the waste rocks distributed throughout the area for the local environmental protection

provenance history of a carboniferous gondwana margin forearc basin new england fold belt eastern australia modal and geochemical constraints abstract the visean stephanian myall trough eastern australia formed part of a forearc basin to the east of a magmatic arc situated along the palaeo pacific margin of gondwana petrographic modal whole rock geochemistry and mineral phase chemistry of sandstones siltstones conglomerates and associated igneous rocks provide a consistent and coherent data set which indicate sediment derivation from a magmatic arc of predominantly silicic volcanic composition the low quartz modes of the sandstones the largely volcanic origin of lithic fragments and the overall high sio 2 content of the siliciclastic sediments and igneous rocks require the arc source to be largely dacitic to rhyolitic in composition the predominance of vitric type highly siliceous volcanic rocks lithic fragments suggests a source composed largely of silicic pyroclastics the presence of potassium feldspar as well as the presence of biotite as the principal detrital ferromagnesian phase in the sandstones suggest a source of medium to high k tholeiite composition the high trace element abundances of relatively immobile elements such as zr la ce v nb y and th and corresponding high th u zr y la y la sm ratios and low zr th zr nb la th and ti zr ratios for both the igneous rocks and derived siliciclastic sediments in the myall trough also require a high k and or strongly medium k arc source a lack of temporal or spatial trends in the data indicate that the magmatic arc remained of uniform composition throughout the 25 ma interval of strata preserved within the trough the provenance history of the myall trough requires accumulation along an andean type continental margin rather than an intra oceanic arc outboard of the gondwana margin

mineralogical and geochemical characterization of the old tailings dam australia evaluating the effectiveness of a water cover for long term amd control abstract establishing a shallow water cover over tailings deposited in a designated storage facility is one option to limit oxygen diffusion and retard oxidation of sulfides which have the potential to form acid mine drainage amd the old tailings dam otd located at the savage river mine western tasmania contains 38 million tonnes of pyritic tailings deposited from 1967 to 1982 and is actively generating amd the otd was constructed on a natural gradient resulting in sub aerial exposure of the southern area with the northern area under a natural water cover this physical contrast allowed for the examination of tailings mineralogy and geochemistry as a function of water cover depth across the otd tailings samples n 144 depth 1 5 m were collected and subjected to a range of geochemical and mineralogical evaluations tailings from the southern and northern extents of the otd showed similar amd potential based on geochemical nag ph range 2 1 to 4 2 and bulk mineralogical parameters particularly at depth however sulfide alteration index sai assessments highlighted the microscale contrast in oxidation in the sub aerial zone pyrite grains are moderately oxidized to a depth of 0 3 m maximum sai of 6 10 under both gravel fill and oxidized covers with secondary minerals e g ferrihydrite and goethite developed along rims and fractures beneath this mildly oxidized pyrite is seen in fresh tailings sai 2 9 10 to 5 8 10 in the sub aqueous zone the degree of pyrite oxidation demonstrates a direct relationship with cover depth with unoxidized potentially reactive tailings identified from 2 5 m directly beneath an organic rich sediment layer sai 0 to 1 10 these findings are broadly similar to other tailings storage facilities e g fox lake sherritt gordon zn cu mine canada and stekenjokk mine sweden where water covers up to 2 m have successfully reduced amd whilst geotechnical properties of the otd restrict the extension of the water cover pyrite is enriched in cobalt up to 2 6 wt indicating reprocessing of tailings as an alternative management option through adoption of an integrated mineralogical and geochemical characterization approach for tailings assessment robust management strategies after mine closure can be developed

mineralogical and geochemical investigations of silicate rich mine waste from a kyanite mine in central virginia implications for mine waste recycling a kyanite mine in central virginia produces a silicate rich waste stream which accumulates at a rate of 450 000 600 000 tons per year an estimated 27 million tons of this waste stream has accumulated over the past 60 years grain size distribution varies between 1 000 and 0 053 mm and is commonly bimodal with modes typically being 0 425 and 0 250 mm and uniformity coefficients vary from 2 000 to 2 333 hydraulic conductivity values vary from 0 017 to 0 047 cm s mineralogy of the waste stream consists of quartz muscovite kyanite and hematite muscovite grains have distinct chemical compositions with significant na2o content 1 12 2 66 wt tio2 content 0 63 1 68 wt tio2 and fe content expressed as fe2o3 up to 1 37 wt major element compositions of samples were dominated by sio2 87 894 90 997 wt al2o3 6 759 7 741 wt fe2o3 1 136 1 283 wt and k2o 0 369 0 606 wt with other components being 1 000 wt elements of environmental concern v cr ni cu zn as ag sn sb ba hg tl and pb were detected however the concentrations of all elements except ni were below that of the kyanite quartzites in the region from which the waste is derived both major and trace element compositions indicate minimal variation in composition the waste stream has potential for recycling muscovite is suitable for recycling as a paint pigment or other industrial applications muscovite and hematite are commonly intergrown and are interpreted to be material where much of the elements of environmental concern are concentrated reprocessing of the waste stream to separate muscovite from other components may enable the waste stream to be used as constructed wetland media for virginia and nearby states recycling of this mine waste may have a positive impact on the local economy of buckingham county and aid in mitigation of wetland loss

the diavik waste rock project geochemical and microbiological characterization of low sulfide content large scale waste rock test piles abstract two experimental waste rock piles test piles each 15 m in height 60 m 50 m were constructed at the diavik diamond mine in northern canada to study the behavior of low sulfide content waste rock with a similarly low acid neutralization potential in a continuous permafrost region one test pile with an average of 0 035 wt s 4 2 and dissolved metals with a decrease in ph to 1 ni 2 3 mg l 1 cu 3 7 mg l 1 zn 35 g l 1 cd and 3 8 mg l 1 co corresponded to decreases in flow rate which were observed at the end of each field season when the contribution of the total outflow from the central portion of the test pile was greatest bacteria were present each year in spite of annual freeze thaw cycles the microbial community within the type i test pile included a population of neutrophilic s oxidizing bacteria each year changes in the water quality of the type iii test pile effluent were accompanied by changes in the microbial populations populations of acidophilic s oxidizing bacteria and fe oxidizing bacteria became more abundant as the ph decreased and internal test pile temperatures increased irrespective of the cold climate conditions and low s content of the waste rock the geochemical and microbiological results of this study are consistent with other acid mine drainage studies indicating that a series of mineral dissolution precipitation reactions controls ph and metal mobility and transport is controlled by matrix dominated flow and internal temperatures