the iberian type of volcano sedimentary massive sulphide deposits the iberian pyrite belt located in the sw iberian peninsula contains many paleozoic giant and supergiant massive sulphide deposits including the largest individual massive sulphide bodies on earth total ore reserves exceed 1500 mt distributed in eight supergiant deposits 100 mt and a number of other smaller deposits commonly with associated stockwork mineralizations and footwall alteration haloes massive sulphide bodies largely consist of pyrite with subordinated sphalerite galena and chalcopyrite and many other minor phases although substantial differences occur between individual deposits both in mineral abundance and spatial distribution these deposits are considered to be volcanogenic roughly similar to volcanic hosted massive sulphides vhms however our major conclusion is that the iberian type of massive sulphides must be considered as a vhms sub type transitional to shms

coastal seismic wipe outs distribution controlled by pore water salinity abstract the relationship between seismic wipe outs methane accumulation and pore water salinity was investigated using high resolution seismic profiles pore water geochemical measurements and sediment property data from the white oak river estuary north carolina the estuary is a broad shallow drowned river valley filled with organic rich sediment where the salinity changes from fresh to sea water within 10 km uniboom seismic reflection profiles indicate a distinct pattern in the distribution of seismic wipe outs wipe outs dominate the upper estuary but are not observed in the lower estuary sediment pore water chlorinities decrease upstream but the sharpest gradients occur with depth at 50 cm depths in the upper half of the estuary pore waters typically have less than 100 mmol l 1 chloride even though overlying estuarine waters have 300 400 mmol l 1 chloride concave chloride profiles demonstrate that sediments in the upper estuary are actively flushed with fresh water moving upward through the sediments from underlying aquifers the associated decrease in interstitial sulfate concentrations combined with high organic carbon content provides favorable conditions for methane production and accumulation seismic wipe outs are correlated with areas of high methane concentrations and with sediments containing low pore water salinities

lead 210 sediment geochronology in a changing coastal environment abstract sediment accumulation rate studies utilizing excess 210 pb and 137 cs were conducted as part of recent investigations of biogeochemical cycling at a single site in cape lookout bight a rapidly changing coastal basin on the outer banks of north carolina u s a cores three meters in length reveal a depositional history for the bight interior characterized by a gradual transition in texture from coarse grained to fine grained material over the period 1946 1979 this transition is controlled by progressive enclosure of the bight by an active northerly migrating recurved spit the textural gradation is periodically interrupted by layers of well sorted sand associated with major storm events lead 210 data indicate that the upper meter of the sediment has accumulated at a rate of 3 35 to 4 71 g cm 2 yr 1 or approximately 8 4 to 11 8 cm yr 1 at o 0 84 below 120 cm depth dilution of clay and silt by low activity sand necessitates correction of the 210 pb profile in order to establish a geochronology grain size 210 pb distribution measurements at three depths reveal that the specific activity dpm g 1 of clay is 3 2 times that of silt and 24 7 times that of sand corrections of bulk sediment excess 210 pb activities based on these measurements lead to dates for textural changes which are consistent with charted changes in basin morphology and major storm events sixteen 137 cs measurements between 33 241 cm depth reveal a peak activity at 105 115 cm and indicate a minimum sedimentation rate of approximately 2 7 g cm 2 yr 1

biogeochemical cycling in an organic rich coastal marine basin 6 temporal and spatial variations in sulfate reduction rates rates of sulfate reduction were measured over a 3 year period in the anoxic nearshore sediments of cape lookout bight north carolina using both a tube incubation method and a 35s sulfate direct injection technique the methods yielded similar depth integrated rates over the upper 30 cm ranging from less than 10 mol so 4 m 2 y 1 in winter to greater than 50 mol so 4 m 2 y 1 in summer there were also seasonal changes in the arrhenius activation energies for the sulfate reduction rates indicating that the assumption that ea is constant with temperature is not always valid the time averaged annual turnover rate for all three years was 20 4 11 4 mol so 4 m 2 y 1 surface rates ranged seasonally from less than 0 01 to over 3 mm so 4 d 1 between winter and summer respectively a subsurface rate maximum was observed to develop during the summer months which accounted for 28 percent of the annual depth integrated sulfate reduction rate subsurface rate maxima are the result of changes in the chemistry substrate type and or concentration and the microbiology in the sediments the possibility of the subsurface maximum being an artifact of the 35s method is also discussed however the sulfate reduction rates compare well with previous measurements of the carbon sediment water plus burial fluxes and with a depth integrated co2 production rate modelled from a co2 concentration profile from the same site

measurement of depth and site related differences in polysaccharide hydrolysis rates in marine sediments abstract the rates at which organic macromolecules are remineralized and variations in degradation rates with site and depth are critical aspects in calculating the turnover of oceanic organic carbon this work introduces a new approach to measuring extracellular enzymatic hydrolysis rates in seawater and sediments and reports first results from field measurements the technique based on measurements with fluorescently labeled polysaccharides fla polysaccharides was used to measure potential hydrolysis rates of pullulan in sediments at three different sites mud sand sandy mud in kiel bight baltic sea significant depth and site related differences were measured for the enzymatic hydrolysis of fla pullulan the total range of hydrolysis rates for fla pullulan 3 109 cuts nmol glu cm 3 h 1 was considerably higher than rates previously reported for muf glucose in kiel bight sediments the highest rates were measured in mud samples at depths of 0 2 cm and in black banded sands at depths of 5 10 cm while the lowest rates were measured at depths of 8 12 cm in sandy mud samples the results obtained with the new method confirm that at least some types of polysaccharides are rapidly hydrolyzed in marine sediments

authigenic sulfide and carbonate mineral formation in holocene sediments of the baltic sea formation of authigenic sulfides and carbonates in holocene 14c dated sediments is interpreted based on analyses of cations fes s fes2 s corg and sulfur isotopes mineral distribution was studied in thin sections and mineral morphology with sem eds the sediments were deposited in the gotland deep baltic sea during freshwater and brackish stages calcium rich rhodochrosite mnco3 occurs in concentrations up to 17 dw in brackish water sediments and are mainly confined to 0 02 0 5 mm thick laminae the frequency with which these laminae occur suggests that they formed with a periodicity of one to a few years and their purity suggests that formation took place in a few weeks we propose that these carbonate laminae resulted from oxic water inflow to the euxinic basin mn ii dissolved in the water column was rapidly oxidized and large amounts of mn oxides reached the sediment reduction of these mn oxides in a high alkalinity environment facilitated rhodochrosite precipitation at the sediment surface pyrite in the brackish water sediments formed at or above the sediment water interface in an iron limited environment due to alternating oxic and euxinic conditions fes was oxidized resulting in a high fes2 sfes s ratio median 170 formation of iron sulfides in the freshwater sediments occurred below the sediment water interface in a sulfate limited environment as a result of the rapid exhaustion of reactive iron in the brackish water sediments excess h2s diffused downwards to pyritize the uppermost part of the underlying freshwater sediments

remineralization and accumulation of organic carbon and nitrogen in marine sediments of eutrophic bays the case of the bay of concepcion chile abstract the bay of concepcion 36 40 s 73 02 w is a semi enclosed and shallow embayment in which biogeochemical processes are seasonally coupled to coastal upwelling during the austral spring and summer the nutrient cycle in the bay is complex due to the combined effects of a pronounced o2 minimum layer and high nutrient concentrations both originating from subsurface equatorial water during coastal upwelling and a rapid rate of sediment nutrient recycling the sediments are characterized by a high content of organic matter mainly due to the extremely high rates of phytoplankton production and deposition during the upwelling period a black flocculent layer frequently covers the sediment water interface in the inner part of the bay where an extensive mat of beggiatoa spp develops three approaches are used to analyse the extent to which the benthic system recycles or retains nutrients at two stations located at the centre station c st c and mouth station b st b of the bay for a 1 year period march 1996 1997 1 estimation of c and n remineralization rates based on so42 reduction measurements 2 calculation of c and n turnover rates using a diagenetic model applied to total organic carbon and total nitrogen vertical distributions and 3 construction of c and n budgets from direct measurements of sedimentation from a sediment trap and estimates of the c and n burial rates depth integrated so42 reduction rates varied between 3 4 winter and 25 5 summer mmol m 2 d 1 estimated c and n oxidation rates ranged between 7 9 and 87 8 mol c m 2 yr 1 and between 0 9 and 6 9 mol n m 2 yr 1 respectively each approach yielded minor differences in the c and n remineralization rates and also minor differences between both studied stations except when the kinetic model was applied to c and n distribution without including the presence of the flocculent layer the rates of carbon oxidation and sulphate reduction were considerably higher than in other coastal sediments with similar depositional regime the c and n burial rates were 2 23 and 0 21 st c and 1 30 and 0 09 st b mol m 2 yr 1 respectively the c n ratio of the buried fraction was ca 10 6 at st c and 14 4 at st b because the observed differences in burial rates could not be ascribed to distinctive depositional both stations have similar sediment accumulation rates and oceanographic similar o2 concentration and hydrography conditions differences may be due to in part spatial heterogeneity in the supply of organic matter the degree of preservation of organic matter as plankton detritus and nitrogen accumulating bacterial biomass associated with beggiatoa spp at st c may also be involved

on the initiation of metamorphic sulfide anatexis mineral assemblages in common sulfide ore deposits are examined together with phase relations to 1 investigate the pressure temperature conditions required for the onset of metamorphically induced partial melting involving economic minerals and 2 place constraints on the amount of melt produced deposits that contain sulfosalt or telluride minerals may start to melt at conditions ranging from lowest greenschist facies to amphibolite facies deposits lacking sulfosalt and or telluride minerals may begin to melt once p t conditions reach the upper amphibolite facies if galena is present or well into the granulite facies if galena is absent the result is two broad melting domains a lowto medium temperature low melt volume domain involving melting of volumetrically minor sulfosalt and or telluride minerals and a high temperature potentially higher melt volume domain involving partial melting of the major sulfide minerals epithermal gold deposits which are especially rich in sulfosalt minerals are predicted to commence melting at the lowest temperatures of all sulfide deposit types massive pb zn cu deposits may start to melt in the lower to middle amphibolite facies if pyrite and arsenopyrite coexist at these conditions and in the upper amphibolite facies if they do not excepting sulfosalt bearing occurrences massive ni cu pge platinum group element deposits will show little to no melting under common crustal metamorphic conditions whereas disseminated cu deposits are typically incapable of generating melt until the granulite facies is reached when partial melting commences in bornite bearing rocks the volume of polymetallic melt that can be generated in most deposit types is therefore largely a function of the abundance of sulfosalt minerals even at granulite facies conditions this volume is usually less than 0 5 the exception is massive pb zn deposits where melt volumes significantly exceeding 0 5 vol may be segregated into sulfide magma dykes allowing mobilization over large distances

the dissolution of high feo olivine rock from the lovasjarvi intrusion se finland at 25 c as a function of ph the high feo olivine rich rock from the lovasjarvi intrusion 65 olivine 20 plagioclase 8 magnetite 4 pyroxene and 3 serpentine has been proposed as a potential redox active backfill additive in deep high level nuclear waste repositories in this work the authors report on kinetic dissolution studies of this solid under different ph and redox conditions performed by using a flow through methodology assuming that silicon is mainly released to solution from the olivine contained in the solid the experimental results have been adjusted to an empirical rate law as a function of proton concentration the proton concentration reaction orders agree with results found in the literature for both acidic and alkaline ph ranges the calculations conducted with the reactive transport code retraso show that at alkaline ph the olivine rock might have a lower redox buffer capacity than expected

stability of andalusite and sillimanite and the al_ 2 sio_ 5 triple point constraints from the ballachulish aureole scotland andalusite and and sillimanite sil occur in well defined zones in the ballachulish aureole in most of the aureole s sillimanite bearing rocks sillimanite grain diameters range from 2 m to 10 m the boundary between prograde andalusite and prograde sillimanite is constrained to a zone of max 30 m width upgrade of the muscovite quartz andalusite k feldspar h 2 o reaction isograd this boundary is interpreted to correspond to the and sil equilibrium the common occurrence of andalusite well upgrade of the first occurrence of sillimanite is ascribed to sluggish kinetics of the polymorphic inversion the p t position of the and sil equilibrium in the aureole is estimated as 645 20 c and 3 0 0 4 kbar based on a combination of 1 location of the ms qtz and kfs h 2 o reaction corrected for non end member fluid and mineral compositions and 2 independent pressure estimates obtained from equilibria in metapelites marbles calcsilcates and granitoids all in exce

coupling between sedimentary dynamics early diagenetic processes and biogeochemical cycling in the amazon guianas mobile mud belt coastal french guiana coastal french guiana lies within the vast mobile mudbelt that characterizes much of the s american inner shelf downdrift of the amazon river approximately 15 20 of the amazon sediment outfall moves nw along the guianas in part as a series of 20 25 coastal mud waves seasonal studies of a representative migrating mudwave located between kourou and sinnamary french guiana demonstrate that diagenetic properties and biogeochemical cycling are closely coupled to sedimentary dynamics and the refluxing of reduced components between the seabed coastal facies and well oxygenated overlying water an unsteady two zone diagenetic regime is typically present in the shallow subtidal and low intertidal regions a surficial layer usually 0 5 1 m thick is nonsulfidic highly reactive and dominated by fe mn cycling this suboxic layer unconformably overlies more consolidated sediment in which net so42 reduction is often observed and contracts shoreward toward the mangrove fringe as sediments stabilize and become bioturbated the relatively stable intertidal flats are also sites of significant benthic primary production despite suboxic conditions over extensive intervals anaerobic remineralization rates are high co2 0 2 0 6 mm day 1 and often show little evidence of attenuation with depth integrated co2 fluxes are 20 235 mmol m 2 day 1 wet dry season average 120 far exceeding diffusive o2 fluxes into the bottom high reactivity 0 08 day 1 and low c n remineralization release ratios 5 3 of decomposing material imply fresh substrate of marine origin most reduced solid phase fe is present as nonpyritic authigenic fe minerals 20 fe ii is in pyrite and low sedimentary c s ratios 6 8 reflect the generally nonsulfidic conditions a broad range of tracers e g 234th t1 2 24 days 210pb t1 2 22 years seasonal cl profiles and nonsteady state diagenetic models of pore water concentrations and oxidant reductant relationships demonstrate that the upper 0 1 1 m of deposits are reworked and exchanged with overlying water on timescales of 10 days to seasonally thus the seafloor acts as a massive suboxic batch reactor entraining and processing reactive marine plankton regenerating fe mn oxides exchanging metabolites and nutrients with the oxygenated water column and generating suites of nonsulfidic authigenic minerals the apparent paradoxical properties of high remineralization rate low reductant content corg 630 mol g 1 and dominance of suboxic metal cycling are a direct consequence of frequent entrainment of highly reactive organic substrate and simultaneous regeneration of the major fe oxidants in oxygenated water the amazon guianas mobile mudbelt is a zone of extraordinarily intense sedimentary and biogeochemical recycling greatly exceeding stable coastal systems such as salt marshes in material exchange with the sea

biogeochemical cycling in an organic rich coastal marine basin 11 the sedimentary cycling of dissolved free amino acids in the anoxic sediments of cape lookout bight nc concentrations of total dissolved free amino acids tdfaas are highest near the sediment water interface generally 20 to 60 m and decrease to non zero asymptotic concentrations 2 to 5 m at depths greater than 20 cm tdfaas in the overlying waters are 1 m dissolved free amino acid dfaa profiles often show a secondary sub surface maximum in the region between the 1 and 5 mm sulfate isopleths this phenomenon appears to be related to the transition in the sediments of this region from sulfate reduction to methanogenesis aspartic acid glutamic acid aminoglutaric acid glycine and alanine are the major dfaas with depth aminoglutaric acid becomes the dominant dfaa accounting for up to 50 mol the mole percentages of individual amino acids in the dfaa and sedimentary i e acid hydrolyzable pools show some similarities although microbial and abiotic processes cause several differences to exist a steady state diagenetic model which quantifies the processes affecting dfaas in these sediments yields rates of dfaa production and consumption that agree reasonably well with independent estimates of these quantities in cape lookout bight and other anoxic marine sediments the combined results of modelling pore water dfaa and sedimentary amino acid profiles indicate that significant exchange of amino acids occurs between the sediments and pore waters i e there is a much larger gross flux through or turnover of the dfaa pool than there is a net change in the concentration of sedimentary amino acids dfaas produced as intermediates in the remineralization of sedimentary amino acids are both metabolized to inorganic nutrients as well as re incorporated back into the sediments this latter process appears most likely to occur by incorporation of dfaas into sedimentary bacterial biomass although abiotic processes e g geopolymerization may also be of some importance these results demonstrate that the biogeochemistry of dissolved free amino acids in the pore waters of cape lookout bight sediments is dominated by internal transformations i e production from sedimentary amino acids microbial remineralization and reincorporation back into the sediments there is some uncertainty in the magnitude of the flux of dfaas across the sediment water interface although it appears to be of secondary importance when compared to the other sedimentary processes affecting dfaas

mineralogical and geochemical controls on the release of trace elements from slag produced by base and precious metal smelting at abandoned mine sites slag collected from smelter sites associated with historic base metal mines contains elevated concentrations of trace elements such as cu zn and pb weathering of slag piles many of which were deposited along stream banks potentially may release these trace elements into the environment slags were sampled from the ely and elizabeth mines in the vermont copper belt from the copper basin mining district at ducktown tennessee and from the clayton silver mine in the bayhorse mining district idaho in the usa primary phases in the slags include olivine group minerals glass spinels sulfide minerals and native metals for vermont samples glass sulfide minerals and native metals for the ducktown sample and olivine group minerals clinopyroxenes spinels sulfide minerals native metals and other unidentified metallic compounds for clayton slag olivine group minerals and pyroxenes are dominantly fayalitic and hedenbergitic in composition respectively and contain up to 1 25 wt zno spinel minerals range between magnetite and hercynite in composition and contain zn up to 2 07 wt zno ti up to 4 25 wt tio2 and cr up to 1 39 wt cr2o3 cobalt ni cu as ag sb and pb occur in the glass phase sulfides metallic phases and unidentified metallic compounds bulk slag trace element chemistry shows that the metals of the vermont and tennessee slags are dominated by cu 1900 13 500 mg kg and zn 2310 10 200 mg kg whereas the clayton slag is dominated by pb 63 000 mg kg zn 19 700 mg kg cu 7550 mg kg as 555 mg kg sn 363 mg kg and ag 200 mg kg laboratory based leach tests indicate metals can be released under simulated natural conditions leachates from most slags were found to contain elevated concentrations of cu and zn up to 1800 and 470 g l respectively well in excess of the acute toxicity guidelines for aquatic life for the idaho slag the concentration of pb in the leachate 11 000 g l is also in excess of the acute toxicity guideline geochemical modeling of the leachate chemistry suggests that leachates from the vermont tennessee and clayton slags are saturated with amorphous silica and al hydroxide therefore the dissolution of silicate and oxide phases the oxidation of sulfide phases as well as the precipitation of secondary phases may control the composition of leachate from slags the presence of secondary minerals on slag deposits in the field is evidence that these materials are reactive the petrographic data and results of leaching tests from this study indicate slag may be a source of potentially toxic metals at abandoned mine sites

hydrochemical variations and contaminant load in the rio tinto spain during flood events summary the aim of this work is to study the hydrochemical variations during flood events in the rio tinto sw spain three separate rainfall flood events were monitored in october 2004 following the dry season in general concentrations markedly increased following the first event fe from 99 to 1130 mg l q max 0 78 m 3 s while dissolved loads peaked in the second event fe 7 5 kg s cu 0 83 kg s zn 0 82 kg s q max 77 m 3 s and discharge in the third event q max 127 m 3 s this pattern reflects a progressive depletion of metals and sulphate stored in the dry summer as soluble evaporitic salt minerals and concentrated pore fluids with dilution by freshwater becoming increasingly dominant as the month progressed variations in relative concentrations were attributed to oxyhydroxysulphate fe precipitation to relative changes in the sources of acid mine drainage e g salt minerals mine tunnels spoil heaps etc and to differences in the rainfall distributions along the catchment the contaminant load carried by the river during october 2004 was enormous totalling some 770 t of fe 420 t of al 100 t of cu 100 t of zn and 71 t of mn this represents the largest recorded example of this flush out process in an acid mine drainage setting approximately 1000 times more water and 140 8200 times more dissolved elements were carried by the river during october 2004 than during the dry low flow conditions of september 2004 highlighting the key role of flood events in the annual pollutant transport budget of semi arid and arid systems and the need to monitor these events in detail in order to accurately quantify pollutant transport

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

a multiproxy study distinguishes environmental change from diagenetic alteration in the recent sedimentary record of the inner cadiz bay sw spain in this study we reconstruct the recent environmental evolution of the inner cadiz bay using sedimentary records reaching back as far as ad 1700 we report lithological descriptions of the sedimen

gas charged sediments in the ria de arousa short to long term fluctuations repeated surveys at control sites in the gas accumulation fields from the ria de arousa galicia nw spain have shown that the top of the acoustic turbidity fluctuates vertically the vertical movement of gas fronts is more apparent in the gas fields located in the outer ria where fluctuations of up to 1 5 ms 1 1 m have been detected at the inner ria the depth to the top of the gas horizons varied between 0 5 and 1 ms 40 to 80 cm short term diurnal fluctuations associated with the hydrostatic pressure variations of the water column during a tidal cycle have been identified as the most likely factors to explain fluctuations of gas fields in the outer ria at the inner ria gas fields are affected by these short term pressure changes superimposed on long term temperature and salinity variations of bottom water masses this combination produces a different pattern of variation in gas fields from the inner and the outer ria prominent pockmarks and acoustic plumes have also been monitored throughout the three seismic surveys many of these pockmarks exhibit active characteristics including the observance of plumes of escaping fluids and sediment

reactive iron in marine sediments abstract a combined field laboratory study has been undertaken to explore the mineralogy concentrations and reactivity towards sulfide of iron in marine sediments also considered is the importance of bacterial fe liberation in regulating pore water chemistry two contrasting marine environments are included one is the relatively fe poor foam site and the other is the fe rich sediment of the subaqueous mississippi delta results show that oxide minerals are the most important fe phases in early diagenetic pyrite formation however viewed separately lepidocrocite and ferrihydrite are more reactive towards sulfide than goethite and hematite when fe oxides are present in relatively high concentrations dissolved sulfide is nearly absent from sediment pore waters with concomitant high concentrations of dissolved fe even in the presence of active sulfide production by sulfate reduction a combination of experimental results and diagenetic modelling shows that in some sediments pore water fe finds it origin in the bacterial reduction of iron oxides this seems the case even though greater amounts of fe are reduced by reaction of sulfide with iron oxides it appears that distinct microenvironments may exist in marine sediments where in one microenvironment sulfide reacts with fe oxides locally precipitating fe sulfide minerals in another fe reduced and solubilized by microorganisms migrates freely into solution

prediction of the environmental impact of modern slags a petrological and chemical comparative study with roman age slags this work presents a comparative study of roman and modern slags which represent the same type of mining waste but which were produced at vastly different times the natural laboratory in which both materials are found is sao domingos one of the most emblematic of portuguese mining districts in the iberian pyrite belt ipb the methodology included 1 detailed studies of the mineralogy and geochemistry of both materials with a reflected light optical microscope scanning electron microscope sem electron microprobe analyses empa and bulk rock analyses 2 melts thermodynamic software to quantitatively test fractional crystallization of both glassy matrix types 3 twq v 2 32 software for performing internally consistent thermometric calculations and 4 a modified community bureau of reference bcr sequential extraction procedure applied to the chemical speciation of potentially toxic elements the combination of petrologic studies and sequential extraction leaching may be used to evaluate and predict pollution impact on the environment we conclude that a 2000 year time gap has not produced an important modification to the base metal extraction system as reflected by the petrologic similarity of both slags and that considering the total mass of modern slags the transfer rate of metals to the environment over the next 2000 years will be 6 7 t year of fe 1 t year of s 81 1 kg year of zn 55 5 kg year of pb 6 5 kg year of cu 0 7 kg year of as 31 2 g year of sb and 18 3 g year of cr the results demonstrate the pollutant potential of the slags within this ipb mining district as revealed by the spoiled state of the fluvial courses in the region

speciation and stable isotopic compositions of humic sulfur in mud sediment of the east china sea constraints on origins and pathways of organic sulfur formation abstract humic sulfur is commonly the most important pool of organic sulfur os in marine sediments and also important for the budget of total sedimentary sulfur in this study contents and stable sulfur isotopic compositions of hydrolyzable organic sulfur hyos humic acid sulfur ha s and fulvic acid sulfur fa s in one core collected from the east china sea ecs inner shelf were determined to investigate the sources and pathways of os formation and to compare diagenetic geochemistry of ha s and fa s hyos in the core is essentially biological in origin and diagenetically refractory with a fairly low fraction of labile sulfur bearing biomolecules ha s in the core is largely terrigenous residual bio os while fa s is a mixture of marine bio and diagenetic os diag os with the diag os fractions between 44 and 71 both ha s and fa s contents in the core are at the lower ends of the corresponding values reported in the literature the ha in the sediments is diagenetically inert subject to neither significant diagenetic sulfurization nor bio os mineralization loss while the fa is reactive prone to both sulfurization and decomposition loss of diagenetically bound os low contents of humic s i e ha s fa s in the core may suggest that os burial has only minor contribution to the burial of total sulfur in the sediments due to generally low om sulfurization

use of sequential extraction procedure for assessing the environmental impact at regional scale of the sao domingos mine iberian pyrite belt sao domingos is one of the most emblematic portuguese mining districts in the iberian pyrite belt ipb the beginning of mining exploitation in the area has been dated back to pre roman times remaining in activity until 1966 when it was definitely halted the intense mining labours are reflected in the presence of a huge amount of sulphide mining wastes and downstream production of acid mine drainage amd the mining wastes in the area are highly heterogeneous and numerous different types may be recognized including slags iron oxides smelting ashes brittle and blocks of pyrite leaching tank refuses industrial landfill and other residues coming from ore extraction gossan wastes and country rocks the chemical speciation of potentially toxic elements as cd cr cu fe mn pb s sb and zn in all mine wastes from sao domingos was determined by modified bcr sequential extraction procedure european community bureau of reference and combined with the mass volume proportions of each waste to quantify the potential risk of this mining district at regional scale analytical recoveries by sequential extraction with respect to a pseudo total metal content digestion were generally acceptable 100 17 the oxidizable fraction corresponds with metals bound to sulphides and released easily under oxidizing conditions in amd production processes this is the most polluting fraction for the environment in this type of residues part of this fraction is retained by precipitation of soluble secondary minerals in warm periods moving to the bio available fraction that is dissolved in rainy periods just considering the bio available fraction all mine wastes from sao domingos may leach up to 172514 ton of fe 10564 ton of s 6644 ton of pb 2610 ton of zn 1126 ton of mn 1032 ton of cu 183 ton of cr 109 ton of as 34 ton of sb and 0 9 ton of cd the process of precipitation and re dissolution of efflorescent salts formed directly by oxidation of the oxidizable fraction is seasonally repeated which causes an annual self feeding and releasing of the bio available fraction thus the present study shows the pollutant potential of this ipb mining district and explains the spoiled state of the fluvial courses in the region

macro and microstructural analysis of the zhujiafang ductile shear zone hengshan complex tectonic nature and geodynamic implications of the evolution of trans north china orogen