natural and anthropogenic schwertmannites from towada hachimantai national park honshu japan abstract schwertmannite a recently described iron hydroxysulfate mineral ideal formula fe 8 o 8 oh 6 so 4 forms naturally as a fluffy brownish yellow precipitate in lake matsuo goshikinuma iwate prefecture japan during part of the distinctive annual geochemical cycle of the lake the dominant inflow to the lake is anoxic ground water which drains disseminated pyritic deposits and enters through a vent in the lake floor the lake water typically has ph 3 and contains 125 mg l soluble s and 30 mg l soluble fe from approximately september to june each year the lake circulates completely dissolved oxygen levels are relatively high iron oxidizing bacteria thiobacillus ferrooxidans are abundant and the lake is turbid brown as schwertmannite is formed samples have been identified and characterized by x ray powder diffraction x ray fluorescence analysis and by extraction with oxalate and dithionite reagents freshly precipitated samples are predominantly schwertmannite samples that have remained in contact with the lake water for months or more show partial transformation to goethite though the transformation is incomplete in material 30 year in age schwertmannite was also found to be formed in the oxidation processes employed by two plants that treat drainage from disused pyrite mines in japan

stable isotope records of late quaternary climate and hydrology from mediterranean lakes the isomed synthesis lake isotope records can be used to assess the spatial coherency of late quaternary climate change across the circum mediterranean region we place modern and palaeo data within a simple conceptual lake response model to show that the isotope hydrology of most mediterranean lakes has been influenced strongly by water balance even in those systems that are chemically dilute i e freshwater 18o data on biogenic and endogenic carbonates from 24 lake basins are used to reconstruct multi millennial scale trends since the lgm while it is difficult to make direct comparisons between lake records in terms of single climatic parameters coherent regional isotopic trends can be identified during glacial times mediterranean lakes deposited carbonates isotopically heavier in 18o compared to the holocene partly due to source area effects isotopic enrichment was most marked during intervals corresponding to the h1 and younger dryas events confirming that late pleistocene cold stages in the north atlantic region were marked by aridity around much of the mediterranean almost all mediterranean lake records shifted to more depleted isotopic values during the last glacial interglacial transition lgit this shift is the reverse of the trend which characterised the same transition in lakes from northern and central europe and suggests that temperature changes were not an important direct driver of mediterranean lake isotopic records over glacial interglacial timescales in the early holocene many lakes in the eastern part of the region were more depleted isotopically than in recent millennia this corresponds with marine sapropel formation both chronologically and geographically and implies that increases in local rainfall contributed significantly to the creation of a freshwater lid and anoxia in the east mediterranean sea in contrast no such pattern is currently apparent from lake isotope records from the west mediterranean suggesting a possible nw se contrast in climate history during the holocene

holocene climatic changes in the western mediterranean from south east france to south east spain abstract holocene climatic changes along coastal regions from south east france to south east spain were studied using pollen ratios comparing modern pollen rain vegetation and climate along selected transects from the atlantic ocean to the mediterranean we obtained threshold values of two different ratios corresponding to the different climatic conditions along the transects these pollen ratios and threshold values were employed to characterize the holocene climatic changes from nine mediterranean coastal sites the results were compared with data from marine and continental pollen sequences distributed in the western mediterranean basin and with additional regional data independent of human activity lake level fluctuations alpine glacier advance and retreat chronology 14 c anomaly and cooling phases in eastern france and central europe the role of anthropogenic activities and climate on the changes in vegetation is discussed six major changes in vegetation cover were identified they correspond to aridification phases that occurred around 9500 9000 yr bp 10 900 9700 cal bp 7500 7000 yr bp 8400 7600 cal bp 4500 4000 yr bp 5300 4200 cal bp 3700 3300 yr bp 4300 3400 cal bp 2600 1900 yr bp 2850 1730 cal bp and 1300 1000 yr bp 1300 750 cal bp these arid episodes were regional responses to more global climatic changes and determined the changes in the vegetation cover humans undoubtedly enhanced the vegetation changes but none the less had to adapt to these new climatic conditions

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

climatic change on the iberian peninsula recorded in a 30 000 yr pollen record from lake banyoles the banyoles lacustrine sequence shows that the vegetational history of the northeastern iberian peninsula during the last 30 000 yr follows the north atlantic pattern of climatic oscillations the banyoles pollen diagram supported by two calibrated 14c dates and nine u th dates shows a clear interstadial event between 30 000 and 27 000 yr b p a pleniglacial period with minor oscillations that ended abruptly ca 14 420 410 yr b p and a late glacial sequence that records the classical stages described in northern europe the bolling allerod interstade the younger dryas event at 12 000 yr b p u series age and a short warming phase between the younger dryas and the last cold event dated at 11 000 yr b p u series age

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

comparison of stable carbon isotope ratios in the whole wood cellulose and lignin of oak tree rings abstract the stable carbon isotope ratios 13c of whole wood cellulose and acid insoluble lignin from annual latewood increments of quercus robur l from modern and sub fossil wood were measured and their potential use as palaeoenvironmental indicators examined the resulting time series demonstrate a very high degree of coherence with 13c of cellulose isotopically enriched by approximately 3 compared to 13c of lignin the 13c values of all three components are influenced by the climate of july and august modern whole wood retains the strongest climate signal perhaps because its composition is closest to that of leaf sugars in sub fossil wood there is no evidence that differential decay leads to fractionation of carbon within either cellulose or lignin but differential decay can alter the cellulose to lignin ratio

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

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

multiple stable isotopes from oak trees in southwestern scotland and the potential for stable isotope dendroclimatology in maritime climatic regions across much of europe eurasia and n america there exist networks of long tree ring chronologies which under favourable circumstances may be used to provide a record of palaeoclimate information a proportion of these tree ring archives primarily those collected for archaeological dating purposes represent a significant and largely untapped palaeoenvironmental archive such records may be unsuitable for palaeoclimatic reconstruction based solely upon their physical characteristics ring width and density owing to weak or poorly expressed climatic forcing this is especially true of oak chronologies from maritime regions this study explores the potential for extracting a climate signal from such chronologies by comparing the stable isotope ratios of c h and o from the rings of common oak quercus robur trees in southwestern scotland with local and regional meteorological data summer growing season climate influences all three isotopes and the relationships identified are consistent with published empirical and mechanistic studies the climate signal appears strongest in o and weakest in h the c and o series in combination explain 31 of the variance in july august mean temperature measured locally and 26 when compared with a homogenised gridded dataset for the period ad1957 2002 over longer timescales the combination of c and o isotopes may also preserve a significant low frequency signal july august r 2 0 57 9 year running mean ad1879 1998 these findings demonstrate the potential of stable isotope dendroclimatology for investigating climatic change from oak chronologies in maritime regions 2008 published by elsevier b v

carbon isotope behaviour in wood and cellulose during artificial aging abstract modern wood was subjected to an artificial decay process to investigate its behaviour with respect to the stable carbon isotope composition of wood and the corresponding cellulose four different woods were used namely oak quercus robur beech fagus sylvatica pine pinus sylvestris sequoia sequoiadendron giganteum and pure spruce cellulose the process of decay was simulated by heating samples in water at 180 c from minutes to months during the decay period the carbon content of wood increased to almost 70 while the cellulose content decreased gradually to zero the degradation proceeds according to a two stage process an initial very fast break down is followed by a rather slow degradation after a strong discrimination against 13 c during the initial phase the 13c 12c ratio increases again mostly up to its initial value the carbon isotope trend for cellulose shows a similar pattern though it is less pronounced maximum discrimination was 1 relative to the untreated wood 13c values of cellulose decreased by up to 0 3 the 13 c depletion is presumably a consequence of the preferential decomposition of cellulose as compared to lignin data on fossil trees are compared with the results obtained from this treatment of aging the 13 c decrease is in line with observations from these fossil woods but the ensuing 13 c enrichment is at most weakly to be seen

a multiproxy environmental investigation of holocene wood from a submerged conifer forest in lake huron usa remains of a holocene drowned forest in southern lake huron discovered in 12 5 m of water 164 m above sea level 4 5 km east of lexington michigan usa sanilac site provided wood to investigate environment and lake history using several proxies macrofossil evidence indicates a forest comprised primarily of conifers equivalent to the modern rich conifer swamp community despite generally low regional abundance of these species in pollen records ages range from 7095 50 to 6420 70 14 c yr bp but the clustering of stump dates and the development of 2 floating tree ring chronologies suggest a briefer forest interval of no more than c 400 years dendrochronological analysis indicates an environment with high inter annual climate variability stable carbon isotope composition falls within the range of modern trees from this region but the stable oxygen composition is consistent with warmer conditions than today both our tree ring and isotope data provide support for a warmer environment in this region consistent with a mid holocene thermal maximum this drowned forest also provides a dated elevation in the nipissing transgression at about 6420 14 c yr bp 7350 cal yr bp in the southern lake huron basin a few hundred years before reopening of the st clair river drainage

oxygen isotope ratios in fossil wood cellulose isotopic composition of eocene to holocene aged cellulose abstract we measured the 18 o of cellulose 18 o cel extracted from fossil wood collected at 9 sites in the northern and southern hemispheres as a potential source of information about precipitation 18 o 18 o ppt in the past and paleotemperatures the samples had been buried in fluvial sediments for periods of time ranging from ca 45 million to 250 years at the oldest localities high latitude eocene through pliocene age sites in canada and russia mean annual temperature mat estimates derived from the modern relationship between mat and 18 o cel are 6 16 c lower than the mat estimates derived from other biological proxies estimates of pleistocene and holocene mean annual temperatures are close to the modern values at those sites these results are consistent with other recent findings that the mat 18 o ppt relationship across north america was not constant throughout the cenozoic paleo 18 o ppt estimates derived from fossil cellulose and the modern north american relationship between 18 o cel and 18 o ppt are within the current annual range of 18 o ppt values at all locations the middle eocene 18 o ppt we determined from arctic cellulose samples 21 9 is consistent with river water 18 o determined in two other studies 19 1 to 22 these findings provide some evidence that a precipitation 18 o signal may be retained in wood cellulose during millions of years of burial and that latitudinal patterns in 18 o ppt may not have changed much during the past 45 ma these interpretations depend of course on the assumption that the isotopic composition of the cellulose has not changed during burial an assumption for which it is difficult to gather direct evidence xrd analysis shows that the crystalline form of the fossil cellulose we used to estimate paleoprecipitation 18 o and paleo mat is the same as that of modern cellulose and that the samples are free of quartz and iron oxide contaminants that result in negative errors in measured 18 o cel

oxygen isotope ratios of oak in east england implications for reconstructing the isotopic composition of precipitation annual latewood 18o values from oak quercus robur l are presented for the period 1895 1994 for four trees growing in eastern england we demonstrate using the 18o values of precipitation from wallingford 1982 1994 and the longer time series from groningen 1965 1994 that the 18o values of winter precipitation had the strongest influence on the 18o values of tree ring cellulose the influence of winter precipitation on the spring summer formed latewood may be explained by several factors most soil water is replenished during the winter water may take several months to penetrate the unsaturated zone and oaks may sample water from lower in the profile during times of water stress the 18o values of oak latewood cellulose were also significantly p 0 01 correlated with summer relative humidity therefore although precipitation 18o values may be altered by partial isotopic exchange with xylem water and the influence of stomatal conductance upon evapotranspiration some of the original 18o signature remains

geochemistry of highly acidic mine water following disposal into a natural lake with carbonate bedrock abstract acid mine drainage amd from the zn pb ag bi cu deposit of cerro de pasco central peru and waste water from a cu extraction plant has been discharged since 1981 into lake yanamate a natural lake with carbonate bedrock the lake has developed a highly acidic ph of 1 mean lake water chemistry was characterized by 16 775 mg l acidity as caco3 4330 mg l fe and 29 250 mg l so4 mean trace element concentrations were 86 8 mg l cu 493 mg l zn 2 9 mg l pb and 48 mg l as which did not differ greatly from the discharged amd most elements showed increasing concentrations from the surface to the lake bottom at a maximal depth of 41 m e g from 3581 to 5433 mg l fe and 25 609 to 35 959 mg l so4 the variations in the h and o isotope compositions and the element concentrations within the upper 10 m of the water column suggest mixing with recently discharged amd shallow groundwater and precipitation waters below 15 m a stagnant zone had developed gypsum saturation index si 0 25 and anglesite si 0 1 were in equilibrium with lake water jarosite was oversaturated si 1 7 in the upper part of the water column resulting in downward settling and re dissolution in the lower part of the water column si 0 7 accordingly jarosite was only found in sediments from less than 7 m water depth at the lake bottom a layer of gel like material 90 wt water of ph 1 with a total organic c content of up to 4 40 wet wt originated from the kerosene discharge of the cu extraction plant and had contaminant element concentrations similar to the lake water below the organic layer followed a layer of gypsum with ph 1 5 which overlaid the dissolving carbonate sediments of ph 5 3 7 in these two layers the contaminant elements were enriched compared to lake water in the sequence as

synchrotron based x ray study of iron oxide transformations in terraces from the tinto odiel river system influence on arsenic mobility simultaneous analysis of micro x ray diffraction xrd and micro x ray fluorescence xrf based on synchrotron light sources and electron microprobe emp analyses were performed on iron terrace samples taken from tinto odiel river system from the iberian pyrite belt ibp sw iberian peninsula iron terraces are formed during the oxidation and precipitation of dissolved iron along the riverbeds impacted by acid mine drainage amd this paper includes the study of actively forming current terraces and fossil terraces isolated from the stream courses due to the river migration over time the results of the study of current terrace samples from amd affected streams of two ipb abandoned mines tinto santa rosa and cueva de la mora showed that fresh precipitates at the surface are composed primarily of metastable schwertmannite which is gradually transformed at depth over short time scales into goethite sediments of ancient terraces are composed mainly of goethite which most likely originated from the re crystallization of a precursor schwertmannite however at century time scale goethite partially re crystallizes to hematite due to diagenetic processes the transformation rate of goethite into hematite is negatively correlated with grain size and the crystallinity of goethite moreover this transformation is accompanied by an increase in grain size and a decrease in surface area of hematite and a concomitant decrease in arsenic trapped in the solid this increase in the arsenic mobility during the diagenetic maturation should be considered in the development of conceptual and analytical models describing long term fate transport and bioavailability of arsenic in environmental systems

trace metal retention through the schwertmannite to goethite transformation as observed in a field setting alta mine mt abstract solutions draining the alta mine jefferson county mt were contaminated by acid sulfate waters asw generated from anthropogenic exposure of meteoric waters to sulfidic underground mine workings and a waste rock pile in 1999 a remediation effort was initiated in an attempt to improve the quality of water draining the site through removal of the waste rock pile with which these solutions come in contact asw were sampled in the mineshaft prior to entering the waste rock pile and upon discharge from the waste rock pile aquifer near the pile toe asw composition changed as solutions flowed through the waste rock pile due to sulfide and silicate weathering and schwertmannite precipitation schwertmannite and goethite were both sampled in the waste rock pile where a distinct field relation was observed between the two minerals schwertmannite was always in contact with actively flowing asw while goethite was never in direct contact with asw and was generally above the waste rock water table goethite is hypothesized to be re dissolved re precipitated schwertmannite that was deposited under higher flow conditions and subsequently transformed to goethite through exposure to wet dry cycling associated with seasonal fluctuations in the amount of water moving through the hydrogeologic system trace metal concentrations in ammonium oxalate extracts of these minerals provides the first published data on the behavior of multiple trace metals through this phase transformation which has important ramifications for considering schwertmannite as a long term metal sink due to its known metastability with respect to goethite a relative retention scale through this phase transformation of pb zn mn as al cu is potentially applicable to other asw systems

hydrochemical performance and mineralogical evolution of a dispersed alkaline substrate das remediating the highly polluted acid mine drainage in the full scale passive treatment of mina esperanza sw spain acid mine drainage remediation is an unresolved matter in abandoned mining districts around the world development and implementation of passive treatment systems in these areas are commonly focused on engineering and water quality aspects neoformed mineral phases precipitated within the reactive material of these passive treatments account for the removal of pollutants but also can cause clogging and passivation of the reactive substrate after 20 months of operation and monitoring the limestone based passive treatment system implemented in mina esperanza sw spain was sampled to study the relationship between water chemistry mineral composition of the neoformed precipitates and treatment performance water chemical profiles show the existence of three precipitation zones controlled by fe al and zn hydrochemistry and also a migration with time of precipitation zones downward into the reactive material these precipitation zones were also confirmed by a mineral study performed on the solid samples where either schwertmannite and goethite or hydrobasaluminite and zn rich green rust were the mineral phases that controlled the metal removal in the three precipation fe al or zn zones iron and al precipitates were observed to play a critical role in the time evolution of the reactive material hydraulic conductivity furthermore al precipitates passivated to some extent the limestone grains by armoring although migration of the fe precipitation zone and al redissolution later activated the limestone grains a higher proportion of limestone in the reactive mixture and the addition of new reagents to the bottom section of the reactive material to enhance the reducing environment and to promote divalent metal removal are proposed on the basis of this hydrochemical and mineralogical study for a future design for the mina esperanza passive treatment system

population history and palaeoenvironment in the skomantai archaeological site west lithuania two thousand years abstract this paper presents the results of multidisciplinary investigations i e archaeological lithological sedimentological palynological chronological 14 c and thermoluminescence tl geochemical and geophysical to reconstruct the palaeoenvironmental conditions and peculiarities of the population history at the skomantai archaeological site e g hill fort western and southeastern foot settlements w lithuania detailed lithological and sedimentological investigations are applied to describe the cultural formations that comprise two cultural layers both in the skomantai hill fort territory and two foot settlements these formations developed in response to human occupation intervals according to archaeological data 14 c and tl surveys date to the early iron age migration period and the mid 13th c mid 14th c ad when the site burned down after the attacks by the teutonic order collected ceramics suggest that representatives of the west balts barrow culture settled in the area during the early iron age distinct erosive events are most probably related to reconstructing the hill fort coupled with the above mentioned intervals of people activity increased amounts of particular elements i e s br ca mn and p recorded in the cultural layers suggest the predominance of timber constructions in the territory and intensive wood use preliminary results from geomagnetic prospection have provided the opportunity to identify linearly arranged archaeological features that may indicate the location of a former building or fence structure the paleobotanical evidence establishes that human interference in the environment was noticeable during the early middle ages including mixed pastoral arable land use with secale cerealia and fagopyrum cultivation

seasonal variations in the formation of al and si rich fe stromatolites in the highly polluted acid mine drainage of agua agria creek tharsis sw spain abstract the study of the different biotic and abiotic processes involved in the current formation of fe stromatolites in rivers affected by acid mine drainage amd is essential not only to understand this unique and extreme environment but also to achieve a better understanding of the past iron formation on the earth and on mars the fe stromatolites studied in the highly polluted amd in tharsis sw spain revealed a unique mineral assemblage with jarosite and rostite as the most unexpected fe and al phases and goethite and schwertmannite as the main constituents seasonal variations in this region greatly affected the composition of the precipitates and the distribution of diatoms within the fe stromatolites drought and flood events were also recognized in the sedimentary textures and in the mineral assemblages observed of particular layers within the fe stromatolites the characterization of the chemical and mineralogical composition of fe stromatolites in tharsis as well as the different formation mechanisms proposed complement the existing literature on newly formed fe stromatolites and provides new observations to increase our understanding of those extreme environments

arsenic in iron cements developed within tailings of a former metalliferous mine enguiales aveyron france abstract arsenopyrite rich waste from a former metalliferous mine were spread out over the sloping side of a deep valley after processing over the past 30 a they have been subjected to rainfall and acid water originating from the abandoned mine galleries this intensive leaching has led to the formation of thin layers of as fe crusts on the tailings surface acting as a cement x ray diffraction and sem coupled with eds determined that jarosite was present in all mineral samples and could contain a small amount of as 5 7 wt in addition empa and raman microspectroscopy characterised the presence of amorphous as v fe hydrates as well as rare arsenate minerals e g scorodite raman microspectroscopy in particular identified a preponderance of goethite or hematite within the mineral framework of the tailings materials that is likely to sorb recalcitrant as species the characterisation of the components of the tailings enable the identification of their evolution shows the progressive decrease of their as content and emphasises the consequences of the temporary trapping of as in the very acidic and oxidising conditions prevailing in such environments resinous amorphous material was identified as the richest in as with as 17 1 wt this material evolved toward more crystallised phases e g goethite jarosite which contained less as 3 2 wt

climatic interpretation of carbon isotope content of mid holocene archaeological charcoals from eastern anatolia abstract the 13c 12c ratio of juniper charcoals from the archaeological site of arslantepe malatya turkey was analysed for the mid holocene period spanning from 3350 to 2000 years bc in addition modern juniper and deciduous oak specimens were collected during a botanical survey around arslantepe in august 2008 after the evaluation of weather parameters the modern 13c 12c ratio was compared with the archaeological one to infer past seasonal precipitation relative magnitude patterns 13c values obtained from these samples suggest that the present day climate is on average drier than that recorded in the past comparing the 13c juniper record with the already published curve for archaeological charcoals of deciduous oaks from arslantepe it appears that the two curves show similar trends in the short period between ca 2850 and 2500 bc in which the curves are substantially parallel and the 13c difference between them is quite reduced but they are shifted by ca 50 150 years in the rest of the record for the interpretation of the arboreal curves however it was necessary to consider the autoecology of modern plants and the source of the water used for photosynthesis as the two selected trees show 13c curves with rather different patterns overall 13c 12c contrasting ratios in juniper and deciduous oaks suggest that seasonality in rainfall distribution and aquifer recharge played a complex role thus a consistent seasonal contrast in precipitation similar to the one in recent times took place at ca 3350 3100 and 2300 bc indicating that semi arid conditions have occurred in the past in alternation with periods characterised by minor differences in the distribution of annual precipitation in particular the period between ca 2850 and 2500 bc may suggest more humid conditions in late winter early spring the combination of the two records suggests that 1 two periods of drought are found at ca 3350 3100 and at ca 2300 2200 bc and 2 that at present winter precipitation is lower than that recorded during the period 3350 2000 bc and summer aridity less or equal to that recorded ca 2200 bc changes in precipitation seasonality and the complex and the peculiar hydrogeological situation hindered the interpretation of the isotope records the use of two taxa having different autoecology and different growing season allows interpretation of the data in terms of changes in precipitation seasonality and of specific habitat in this complex and peculiar hydrological setting

continental climate response to orbital forcing from biogenic silica records in lake baikal changes in insolation caused by periodic changes in the earth s orbital parameters provide the primary forcing for global ice ages1 6 but it is not clear to what extent the climates in continental interiors are controlled directly by regional variations in insolation and to what extent they are driven instead by the highly nonlinear response of the oceans and ice sheets here we investigate this question using the record of biogenic silica in lake baikal as a proxy for climate change in this high latitude mid continental region we find a good correlation between this record and that of marine oxygen isotopes4 over the past 250 kyr the baikal record exhibits both a strongly nonlinear component manifested in a 100 kyr periodicity and weaker direct insolation components manifested in the 41 kyr obliquity and 23 and 19 kyr precession orbital cycles these results show that even though extreme continental climates such as this are influenced directly by insolation variations they are dominated by the nonlinear rhythm of the oceans and ice sheets

climate signals in tree ring width density and δ13c from larches in eastern siberia russia abstract we present the first and longest 413 years dataset on stable carbon isotope ratios in tree ring cellulose 13c tree ring width trw and maximum latewood density mxd obtained from larch trees growing on permafrost under continental climate in the suntar khayata mountain ridge in eastern siberia russia with this first study we calibrate tree ring parameters against climate quantities and based on these results assess the potential added value of mxd and especially of 13c complementing trw analysis for future climate reconstruction purposes 13c chronologies were corrected for human induced changes in atmospheric co2 since ad 1800 two different approaches were compared i a correction referring merely to the decline in atmospheric 13c 13catm and ii a correction additionally accounting for the increase in atmospheric partial pressure of co2 13c chronologies are characterized by strong signal strength with only 4 trees representing the population signal at the site mean inter series correlation 0 71 and eps 0 90 13c variation shows low similarity to trw and mxd while correlation between trw and mxd is highly significant correlation analysis of tree ring parameters with gridded instrumental data climate research unit cru ts 2 1 over the ad 1929 2000 calibration period demonstrates that trw and mxd react as reported from other sites at cold and humid northern latitudes precipitation plays no significant role but strong dependencies on monthly mean maximum and minimum temperatures particularly of the current summer june to august are found up to r 0 60 p

climate at the onset of western mediterranean agriculture expansion evidence from stable isotopes of sub fossil oak tree rings in spain climate conditions during the early holocene may have contributed to the spread of old world agriculture from its area of birth in the fertile crescent near east west through the mediterranean basin reconstructing the specific environmental conditions existing in early agricultural settlements of the western mediterranean may help to elucidate this point the aim of this work was to gain information on past climate of one of the earliest agricultural settlements of the iberian peninsula la draga a lacustrine site dating back to the 2nd half of the 8th millennium bp in which post fragments of deciduous oak have been exceptionally well preserved in an anaerobic environment sub fossil wood we studied the relationship between climate factors and carbon isotope discrimination 13c and oxygen isotope composition 18o in wood cellulose from modern tree ring series of quercus humilis mill and quercus petraea matt liebl recovered from the area climatic responses observed in extant material were used to interpret the isotopic signal of wood cellulose extracted from sub fossil wood results showed that water availability of late spring early summer and september influences 13c and 18o which allows their use as proxies for palaeoclimatic reconstruction differences between sub fossil and extant samples in 13c 19 35 vs 18 02 and 18o 26 32 vs 29 28 records suggest slightly lower temperatures and higher plant water availability than at present during the establishment of agriculture at the site these results seem to disprove the existence of an environmental limitation preventing continuation of hunting and gathering activities as a cause for the adoption of agriculture in this early agricultural site on the iberian peninsula

reconstruction of holocene climate in southern france and eastern spain using quantitative anatomy of olive wood and archaeological charcoal quantitative anatomical analysis of wild olive wood demonstrates that certain criteria are determined by climatic factors regression models developed from modern calibration samples located in french and spanish mediterranean regions and charred under controlled thermal and atmospheric conditions allow us to quantify the response of vessel density and hydraulic conductivity to mean annual temperature and mean annual precipitation respectively from these predictive models climatic conditions are compared with data from wild olive charcoal from three different archaeological sites la cova de l esperit and montou france la cova de les cendres spain although archaeological charcoal results from the partial combustion of wood collected by man around settlements the available samples are sufficiently numerous to infer regional palaeoclimatic conditions they allow us to estimate the climatic changes that occurred in southern france roussillon and eastern spain levante during the holocene period the reconstructed mean annual temperature conditions show low variations throughout each site an increase from 1 to 1 5 c is recorded in southern france at the beginning of the subatlantic chronozone and could be related to the expansion of thermophilous vegetation including olea which is traditionally attributed to anthropogenic influence the mean annual precipitation curves fluctuate to a much greater extent they show positive oscillations wet phases at the atlantic chronozone and at the transition between the subboreal and the subatlantic in spain bioclimatic conditions comparable to those of the present day are recorded during the subboreal chronozone in southern france the onset of modern thermic conditions seems to be reached only during the subatlantic chronozone finally at the latitudes 39 40 n and 43 44 n the onset of the modern mediterranean climate in terms of temperature and precipitation occurred simultaneously about 3000 years ago

an annual resolution stable isotope record from swiss subfossil pine trees growing in the late glacial abstract previous studies have suggested that the late glacial period lg 14 600 11 700 cal bp was characterised by abrupt and extreme climate variability over the european sector of the north atlantic the limited number of precisely dated high resolution proxy records however restricts our understanding of climate dynamics through the lg here we present the first annually resolved tree cellulose stable oxygen and carbon isotope chronology 18otree 13ctree covering the lg between 14 050 and 12 795 cal bp generated from a swiss pine trees p sylvestris 27 trees 1255 years comparisons of 18otree with regional lake and ice core 18o records reveal that lg climatic changes over the north atlantic as recorded by greenland stadials and inter stadials were not all experienced to the same degree in the swiss trees possible explanations include 1 lg climate oscillations may be less extreme during the summer in switzerland 2 tree ring 18o may capture local precipitation and humidity changes and or 3 decayed cellulose and various micro site conditions may overprint large scale temperature trends found in other 18o records despite these challenges our study emphasises the potential to investigate hydroclimate conditions using subfossil pine stable isotopes

stable carbon isotope ratios of pinus sylvestris from northern finland and the potential for extracting a climate signal from long fennoscandian chronologies stable carbon isotope ratios were measured on the latewood cellulose of 36 scots pine trees from four sites in northern finland 13c values were corrected for changes in the 13c of air and de trended to remove the effect of tree age simple linear and multivariate correlations were used to determine the nature and strength of any climate signal at three sites the dominant controls are in descending order summer sunshine temperature and antecedent precipitation at the fourth site the dominant controls are antecedent precipitation and air relative humidity while summer sunshine and temperature appear unimportant 13c values record changes in the concentration of co2 in the stomatal chambers which reflects the balance between stomatal conductance and photosynthetic rate photosynthetic rate is controlled primarily by photon flux sunshine and temperature suggesting that this dominates at three of the sites whereas stomatal conductance is controlled by air humidity and soil moisture status ant

iron mineralogy across the oxycline of a lignite mine lake iron rich pelagic aggregates of microbial origin named iron snow are formed in the water column of some acidic lignite mine lakes we investigated the evolution of fe mineralogy across the oxycline of the lusatian lake 77 germany at two sampling sites differing by their ph and mixing profiles the central basin cb of this lake shows a dimictic water regime with a non permanent anoxic deep layer and a homogeneous acidic ph all over the water column ph 3 in contrast the northern basin nb is meromictic with a permanently anoxic bottom layer and a ph increase from ph 3 in the mixolimnion superficial part of the lake to ph 5 5 in the monimolimnion anoxic bottom layer fe minerals above and below the oxycline were identified using x ray absorption spectroscopy xas at the fe k edge and further characterized down to the atomic scale by high resolution transmission electron microscopy hrtem and scanning transmission electron microscopy stem coupled to energy dispersive x ray spectroscopy edxs we explored local fe redox state and c speciation using scanning transmission x ray microscopy stxm at the fe l2 3 edges and c k edge schwertmannite fe8o8 oh 8 2x so4 x identified as the sole fe mineral in cb was polycrystalline consisting in the aggregation of nanodomains of 2 3 nm each one exhibiting the crystal structure of schwertmannite in contrast schwertmannite was partly 40 converted to aluminous ferrihydrite when reaching the oxycline in nb this mineralogical transformation was most probably due to a combination of abiotic and microbial anaerobic processes promoting ph increase and release of fe ii e g via heterotrophic fe iii reduction that induce the catalytic hydrolysis of schwertmannite to ferrihydrite mineral products were stabilized in the monimolimnion by the adsorption of aluminum silicate and organic matter noteworthy local fe redox state heterogeneities were observed with a few areas enriched in fe ii as evidenced by stxm analyses at the fe l2 3 edges these local redox heterogeneities could arise from microbial activity e g fe iii and or sulfate reduction all these results provide an in depth mineralogical overview of iron phases forming in lake 77 as a basis for future investigations of microbial vs abiotic parameters controlling their stability and transformation

stable isotope coherence in the earlywood and latewood of tree line conifers abstract annually resolved and replicated tree ring stable isotope series have the potential to reconstruct growing season environmental parameters over multi millennial timescales as this archive may require only minimal statistical detrending it has the potential to preserve a large portion of low frequency climate signals to date many studies have utilised only the latewood portion of the tree ring in an attempt to minimize carry over effects from previous year reserves and maximise the annual nature of the climate signal preserved however the old trees from tree line locations necessary to build long chronologies often display narrow ring widths