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1.	Kielman, Ross, 1991-, et al. (författare) U-Pb age distribution recorded in zircons from Archean quartzites in the Mt. Alfred area, Yilgarn Craton, Western Australia 2018 Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 310, s. 278-290 Tidskriftsartikel (refereegranskat)abstract The U-Th-Pb isotopic data from detrital zircon grains from five samples of Archean quartzite from the Mt. Alfred area of the Illaara greenstone belt in the Yilgarn Craton of Western Australia are presented in this study. The zircon grains are typically fractured and contain both irregular and oscillatory zoned internal structures as revealed by cathodoluminescence imaging. Concordant 207Pb/206Pb ages range between 3109 ± 17 and 3918 ± 16 Ma (2σ), with three main age peaks at ca. 3640, 3690 and 3760 Ma. Older 207Pb/206Pb ages up to 4067 ± 5 Ma are strongly affected by at least one recent disturbance event, however one single-grain discordia yields an upper intercept age of 4107 ± 12 (MSWD = 1.2). A further sixteen zircon grains with multiple analyses define discordia that suggest U-Pb disturbance events in the Neoarchean and the Mesozoic, the latter as a result of invasive low temperature weathering solutions. The notable lack of grains with ages less than ∼3.6 Ga in the Mt. Alfred detrital zircon population differentiates it from other quartzite samples from both the Illaara Formation and the Eoarchean zircon-bearing metasedimentary rocks of the Narryer Terrane. Also, the limited spread of zircon ages between 3640 and 3760 Ma suggests a relatively uniform and possibly local source region. However, no rocks of this age have been found in the Youanmi Terrane. This implies either the distal transport of similarly aged clastic sediments at 3.1 Ga from the Narryer Gneiss Complex (NGC) to the Mt. Alfred area, or the previous existence of NGC-like rocks near the Illaara greenstone belt that are either not currently recognised or have since been destroyed.
2.	Widerlund, Anders, et al. (författare) Early diagenesis and isotopic composition of lead in Lake Laisan, northern Sweden 2002 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 189:3-4, s. 183-197 Tidskriftsartikel (refereegranskat)abstract Water column (dissolved/suspended phase, sediment traps) and sediment data (pore-water, solid-phase sediment) were combined with stable Pb and 210Pb isotope data to trace the early diagenetic behaviour and geochemical cycling of Pb in Lake Laisan, a lake which has received large quantities of anthropogenic Pb since the early 1940s. Early diagenetic remobilisation of Pb is indicated by a subsurface pore-water Pb maximum (120 µg 1-1) in the oxic surface layer of the sediment, where the solid-phase Pb concentration is 3400-4600 µg g-1. The remobilisation of Pb appears to be caused by a pH-controlled desorption of Pb from solid-phase sediment, which is consistent with a model describing surface complexation of Pb(II) on hydrous goethite surfaces. The diffusive Pb flux from the subsurface pore-water maximum towards the sediment surface (36 µg cm-2 year -1) exceeds the depositional Pb flux (8.6 µg cm -2 year -1) by approximately a factor of four, indicating that Pb is highly mobile in the sediment. Stable Pb isotope data and a mass balance calculation suggest that Pb diffusing upwards is, to a large extent, trapped in the surface sediment. Lead that may diffuse into the slightly alkaline lake water appears to be efficiently sorbed to suspended particulate matter, resulting in low dissolved Pb concentrations in the water column (0.040-0.046 µg 1-1). Sorption of Pb to suspended particulate matter is consistent with the elevated suspended particulate Pb concentrations in the hypolimnion (3800-4000 µg g-1), and the fact that the stable Pb isotopic compositions of suspended matter and pore-water are similar. © 2002 Elsevier Science B.V. All rights reserved.
3.	Boström, Kurt, et al. (författare) Biological matter as a source of authigenic matter in pelagic sediments 1978 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 23:1-4, s. 11-20 Tidskriftsartikel (refereegranskat)abstract Pelagic sediments are rich in components that appear to have formed from seawater, so-called authigenic deposits. Such authigenic components are commonly well oxidized and are rich in many metals such as Cu, Co and Ni. On the other hand, most of these metals have restricted solubilities and very short residence times in seawater. True authigenesis can therefore only account for little of the "authigenic"-looking matter in the deep sea.Conservative mixing models, using average terrigenous matter, average marine biological matter, average volcanic matter (East Pacific Rise-emanation) and average basaltic matter, produce model sediments that are strikingly similar to real sediments.In the model sediments several of the trace-element abundances for instance those for Cu, Ni and Ba can only be explained by a large admixture of biological matter. Several of these elements are enriched in the authigenic phases in deep-sea sediments. This implies that most components that generally have been considered as authigenic are rearranged decay products of biological material.
4.	Boström, Kurt, et al. (författare) Plankton: Its chemical composition and its significance as a source of pelagic sediments 1974 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 14:4, s. 255-271 Tidskriftsartikel (refereegranskat)abstract The absolute concentrations of minor and trace elements vary considerably in plankton. However, normalization of elemental abundances versus the minor elements Fe, Al and Zn (instead of the commonly used normalization versus seawater concentrations) demonstrates that these elements show remarkably constant proportions vis à vis each other. Thus, Ti, Fe, Al, Mn, V, and Zr occur in marine lower organisms in the same proportions as in the average shale, whereas Ba, Cr, Cu, Ni, Cd, Pb, Zn and B are enriched relative to the shale abundances, as are also Ca, Mg, Na, K, and Sr. These patterns appear to suggest that marine plankton are rich in lithogenic matter, but this is probably not the normal case.Contrary to the uniformity of plankton, sediments from the Pacific vary considerably in composition. Under the Equatorial high-productivity region the sediments show striking similarities with a mixture of average shale and average plankton mass, as could be expected, whereas sediments from the East Pacific Rise differ considerably from such mixtures. An iron-manganese phase (of deep-seated origin?), mixed with biological matter, on the other hand, yields model sediments with remarkable similarities to the East Pacific Rise deposits. It is therefore likely that biological processes account for a considerable fraction of some elements such as Cu, Ni, Zn and Ba also in the East Pacific Rise metalliferous sediments.
5.	Boström, Kurt, et al. (författare) The origin of iron-rich muds at the Kameni Islands, Santorini, Greece 1984 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 42:1-4, s. 203-218 Tidskriftsartikel (refereegranskat)abstract Hydrothermal sediments form in several places within the Santorini caldera. The sediments at the most active hot submarine spring (at SW Nea Kameni) consist of 40-48% Fe2O3 and 8-15% SiO2, but only little Al2O3 (0.5-1.6%), P (0.1-0.3%), Mn (100-450 ppm), Sr, Zr, Ba, Zn and V (∼30-200 ppm) and Cu, Ni and Y (∼ 1-30 ppm) are present. The sediments contain more Fe and P and less Si, Al, Mn and many trace elements than sediments formed at less active springs at Palaea Kameni; the differences probably being caused by faster deposition rates of Fe at Nea Kameni and less dilution by rock detritus, which delivers Al, Si and Mn. The Santorini sediments differ much from other exhalative sediments at present or old spreading centers, for example on the East Pacific Rise, in the Red Sea or at En Kafala, which are rich in Mn, Cu, Zn, Ni and Ba. Hydrothermal rock leaching probably occurs at much lower pH-values at Santorini than on the East Pacific Rise, causing a more complete breakdown of the leached rock at Santorini. The very low trace element to iron ratios in the rocks at Santorini, therefore, prevent the hydrothermal solutions there from being very rich in trace elements. The very acid leaching solutions at Santorini are created by extensive oxidation of hydrogen sulfide to sulfuric acid, a process that is readily possible due to the close proximity of the oxygen-rich atmosphere to the top of the magma chamber.
6.	Gustafsson, Jon Petter (författare) Modelling molybdate and tungstate adsorption to ferrihydrite 2003 Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 200:02-jan, s. 105-115 Tidskriftsartikel (refereegranskat)abstract The environmental geochemistry of molybdenum and tungsten is not well known. To enable predictions of Mo and W concentrations in the presence of ferrihydrite (hydrous ferric oxide), batch equilibrations were made with MoO42-, WO42-, o-phosphate (PO43-) and freshly prepared ferrihydrite suspensions in 0.01 M NaNO3 in the pH range from 3 to 10 at 25°C. The results showed that WO42- is adsorbed more strongly than MoO42- , and that both ions are able to displace PO43- from adsorption sites at low pH. Two models, the Diffuse Layer Model (DLM) and the CD-MUSIC Model (CDM), were tested in an effort to describe the data. In both models, the adsorption of MoO42- and WO42- could be described with the use of two monodentate complexes. One of these was a fully protonated complex, equivalent to adsorbed molybdic or tungstic acid, which was required to fit the data at low pH. This was found to be the case also for a data set with goethite. In competitive systems with PO43- , the models did not always provide satisfactory predictions. It was suggested this may be partly due to the uncertainty in the PO43- complexation constants.
7.	Herbert, Roger, et al. (författare) Surface chemistry and morphology of poorly crystalline iron sulfides precipitated in media containing sulfate-reducing bacteria 1998 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 144:1-2, s. 87-97 Tidskriftsartikel (refereegranskat)abstract This study characterizes the surface chemistry and morphology of poorly crystalline iron sulfides precipitated in a chemically defined growth media for sulfate-reducing bacteria. The precipitates were analyzed by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Based on XRD results, the precipitates exhibit only incipient crystallization with a single broad diffraction peak at about 5 Angstrom, characteristic of disordered mackinawite. The iron sulfides generally exhibit a platy habit with particles 100 to 300 nm in diameter; these particles appear often in 1 to 2 mu m spherical aggregates. The XPS results indicate that the Fe(2p(3/2)) spectrum for poorly crystalline iron sulfide can be fitted with Fe(II) and Fe(III) components, both corresponding to Fe-S bond types, The absence of oxide oxygen in the O(1s) spectrum and Fe(III)-O bond types in the Fe(2p(3/2)) spectrum supports the conclusion that the poorly crystalline iron sulfides are composed of both ferric and ferrous iron coordinated with monosulfide, with lesser amounts of disulfide and polysulfides also present. These results suggest that the precipitates possess a surface composition similar to greigite, with the remaining mineral mass composed of disordered mackinawite.
8.	Ingri, Johan, et al. (författare) Iron and manganese layering in recent sediments in the Gulf of Bothnia 1986 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 56:1-2, s. 105-116 Tidskriftsartikel (refereegranskat)abstract The oxidized surface layer of recent soft sediments in the Gulf of Bothnia, northern part of the Baltic Sea, has been investigated. Distinct stratification of Fe and Mn is observed, with up to five different horizons in well-developed profiles. These layered top sediments, although not previously noticed, occur extensively in the Gulf of Bothnia. There is a close association of Mn and Ni, Ba, Zn and Cu, whereas P, Ca and Sr are associated with Fe. High dissolved Fe and Mn contents coupled with a strong redox gradient are recorded in the interstitial waters. Formation of these layers is linked to varying redox conditions. Fe and Mn tend to be dissolved under reducing conditions, to migrate upwards and to reprecipitate as oxyhydroxides along favourable redox horizons. Reaching oxidizing conditions Fe precipitates prior to Mn, and is always found below the Mnrich strata. The character of the oxidized zone is quite different in the two sub-basins of the Gulf of Bothnia. Mn-rich horizons together with spherical Mn-rich nodules are frequently found in the Bothnian Bay, while in the Bothnian Sea mostly Fe-rich layers are present together with abundant Fe-rich flat concretions. This difference is interpreted as being due to a lower redox level in the Bothnian Sea.
9.	Ingri, Johan, et al. (författare) Temporal variations in the fractionation of the rare earth elements in a boreal river; the role of colloidal particles. 2000 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 166:1-2, s. 23-45 Tidskriftsartikel (refereegranskat)abstract Rare earth element (REE) data from weekly sampling of the filtered (<0.45 μm) and suspended particulate phase during 18 months in the Kalix River, Northern Sweden, are presented together with data on colloidal particles and the solution fraction (<3 kDa). The filtered REE concentration show large seasonal and temporal variations in the river. Lanthanum varied between approximately 300 and 2100 pM. High REE concentration in the filter-passing fraction is related to increased water discharge and there is a strong correlation between the REE concentration, organic carbon, Al and Fe. Physical erosion of detrital particles plays a minor role for the yearly transport of particulate REE in this boreal river system. The suspended particulate fraction, which is dominated by non-detrital fractions, accounted for only 35% of the yearly total transport of La in the river. Approximately 10% of the REE were transported in detrital particles during winter. At spring-flood in May, about 30% of the LREE and up to 60% of the HREE where hosted in detrital particles. Ultrafiltration of river water during spring-flood shows that colloidal particles dominate the transport of filter-passing REE. Less than 5% of the filtered REE are found in the fraction smaller than 3 kDa. The colloidal fraction shows a flat to slightly LREE enriched pattern whereas the solution fraction (<3 kDa) show an HREE enriched pattern, compared with till in the catchment. Suspended particles show a LREE enriched pattern. Data indicate that the REE are associated with two phases in the colloidal (and particulate) fraction, an organic-rich phase (with associated Al-Fe) and an Fe-rich (Fe-oxyhydroxide) inorganic phase. The Ce-anomaly in the suspended particulate fraction in the river shows systematic variations, and can be used to interpret fractionation processes of the REE during weathering and transport. There was no anomaly at maximum spring-flood but during the ice-covered period the anomaly became more and more negative. The temporal and seasonal variations of the Ce-anomaly in the suspended particulate phase reflect transport of REE-C-Al-Fe-enriched colloids from the upper section of the till (and/or from mires) to the river at storm events.
10.	Land, Magnus, et al. (författare) Seasonal variations in the geochemistry of shallow groundwater hosted in granitic till 1997 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 143:3-4, s. 205-216 Tidskriftsartikel (refereegranskat)abstract The groundwater chemistry in a small catchment in northern Sweden has been studied for a period of 15 months, including two snowmelt events. The groundwater was sampled from two wells in a slope facing a small stream. One well was placed at the top of the slope (28 m from the stream), and the other was placed closer to the stream (13 m from the stream). Both wells were completed to approximately the same elevation (1.5 m below the stream bed). In addition to groundwater compositions, the chemical composition of precipitation, soil water and stream water was investigated. The chemical composition of the groundwater in the well farther from the stream was fairly constant during the studied period. In the closer well the concentrations of Ca, Mg, Na, Sr, Si, and alkalinity decreased by approximately 10% during snowmelt in May. In contrast, the concentrations of Fe, Al, Ce and Cu increased. After the snowmelt, during June and July, the concentrations of Ca, Mg, Na, Sr, Si, and alkalinity in the closer well increased by a factor of 2–5 compared with the concentrations prior to the snowmelt. By August, the concentrations had decreased to the same levels as before the snowmelt and remained constant until next snowmelt. To explain these variations the Ca/Sr ratio was used as a natural chemical tracer for different water masses. It was found that the increased concentrations of Ca, Mg, Na, Sr, Si, and alkalinity during summer was caused by changes in the groundwater flow direction, which resulted in upwelling of deeper groundwater. At this time the area at the closer well acted as an unsaturated discharge area. The concentrations of Fe, Al, Ce and Cu decreased rapidly after the snowmelt and then remained constant except for two peaks in July and August. These variations were due to mixing with rapidly percolating soil water from the E-horizon and melt water or rain water, which is supported by increased content of dissolved oxygen.
11.	Land, Magnus, et al. (författare) Solid speciation and fractionation of rare earth elements in a Spodosol profile from northern Sweden as revealed by sequential extraction 1999 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 160:1-2, s. 121-138 Tidskriftsartikel (refereegranskat)abstract A sequential extraction has been carried out on seven soil samples from a spodosol profile in till with granitic composition. The soil profile was sampled in northern Sweden. Five fractions were selected for extraction: (A) CH3COONa-extractable (exchangeable/adsorbed/carbonate); (B) Na4P2O7-extractable (labile organics); (C) 0.25 M NH2OH⋅HCl-extractable (amorphous Fe-oxyhydroxides/Mn-oxides); (D) 1 M NH2OH⋅HCl-extractable (crystalline Fe-oxides); and (E) KClO3/HCl-extractable (organics and sulphides). Extracted rare earth elements (REE) were determined with High Resolution ICP-MS. In addition to the soil, stream water suspended particulate matter was also analysed for REE. Total concentrations in the soil samples show that the REE have been fractionated during weathering. In the acidic (pH 4.28) E-horizon all REE are depleted relative to the unweathered till. The depletion decreases with increasing atomic number. Also in the B-horizon (pH 5.86) the REE are depleted, although to a lesser extent compared to the E-horizon. Secondary phases in the B-horizon fractionate the REE in different ways. Rare earth elements extracted in extractions A and C were enriched in the intermediate REE relative to heavy and light REE if normalized to local till. In extractions B and D, the heavy REE were enriched relative to the light REE, and in extraction E a large enrichment of light REE relative to heavy REE was found. Stream water suspended particulate matter is enriched in all REE relative to local till. The light REE are more enriched than the heavy REE. Normalized La/Lu ratios in the suspended matter ranged from 1.5 to 2.4, and were negatively correlated with stream water discharge as well as with content of detrital inorganic matter in the suspended load. The only extracted phase that potentially can explain the high normalized La/Lu ratio in the suspended matter is the phase extracted in extraction E, which has a ratio of 2.0–4.2. The normalized La/Lu ratio for the rest of the extractions ranged from 0.5 to 1.2. It is concluded that organic matter seems to be important for the particulate transport of REE in northern coniferous areas.
12.	Moore, Cynthia, et al. (författare) The elemental compositions of lower marine organisms 1978 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 23:1-4, s. 1-9 Tidskriftsartikel (refereegranskat)abstract A study of 33 new and 87 previous analyses of marine biological matter shows that the proportions of the minor and trace elements (Ti, Fe, Al, Mn, Cr, Cu, Ni, Cd, B, V, Zr and Mo) in lower marine organisms scatter much less than the major elements Na, K, Sr and SiO2 do. Particularly small variations are found for Ti, Fe, Al, Mn, Cr, Cu, Cd and V. Scatter ranges between these extremes are found for Ca, Mg, Ba, Pb and Zn. Biological matter from the Pacific and the Atlantic Oceans show almost identical trace- and minor-element compositions with significant discrepancies only for Al and Zn. Pacific samples are rich in Zn and Atlantic samples are enriched in Al.
13.	Peinerud, Elsa K., et al. (författare) Non-detrital Si concentrations as an estimate of diatom concentrations in lake sediments and suspended material 2001 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 177:3-4, s. 229-239 Tidskriftsartikel (refereegranskat)abstract This paper evaluates a method, based on normalization with Al, to estimate the concentration of diatoms in suspended and deposited sediments. Provided that Al exists primarily in the detrital phase, one can calculate the fraction of non-detrital Si (i.e. biogenic Si). Suspended matter and sediment in two lakes in northern Sweden have been analyzed. Results from the normalization method are compared with microscope count data. The results from the two methods differ somewhat. Partly dissolved diatom frustules may explain part of this discrepancy. These remnants can hardly be recognized as diatoms. Therefore, they are not counted during the microscopic analysis, although they contribute to the concentration of biogenic Si. Another factor is the differences in Si content among different types of diatoms. We show that the calculated concentrations of non-detrital Si are good estimates of the diatom concentrations. By using normalization as a tool, reasonable estimates of the stocks of biogenic Si can be obtained rapidly. Using these estimates as a guide, sites where considerable changes in diatom productivity and/or dissolution rates have occurred can be identified.
14.	Pettersson, Ulf T., et al. (författare) The geochemistry of Co and Cu in the Kafue River as it drains the Copperbelt mining area, Zambia 2001 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 177:3-4, s. 399-414 Tidskriftsartikel (refereegranskat)abstract Samples of the dissolved ( < 0.45 μ m) and suspended (> 0.45 μ m) phases have been collected in the Kafue River during a 1-year cycle. Within the mining area, the concentrations of Co, Cu and S in the river occasionally increase more than 100 times compared to concentrations upstream from the mining area. The highest concentrations of dissolved Cu (3.4 μ M) and Fe (4.2 μ M) are found during high water discharge, probably indicating a washout of leached weathering products from spoil heaps. High levels of Co appear to originate from one point source, the location where the Co ore is treated. In the Kafue River, secondary Mn- and Fe-rich particles are formed, on which Co and Cu, respectively, are enriched. The elements associated to secondary Fe and Mn particles are enriched at the sediment surface in the river due to redox processes. Hence, secondary particles and sorbed trace elements may be resuspended and transported further downstream in the river system. However, very high concentrations of Cu (1%) and Co (0.1%) in the sediment are caused by primary sulphides.
15.	Pontér, Christer, et al. (författare) Temporal variations in dissolved and suspended iron and manganese in the Kalix River, northern Sweden 1990 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 81:1-2, s. 121-131 Tidskriftsartikel (refereegranskat)abstract Particulate and dissolved Fe and Mn were measured once a week from May to September 1982 in the Kalix River, north Sweden. During winter baseflow the dissolved Fe concentration was 450 mu g 1 super(-1). Early snow-melt discharge increased the concentration slightly but during springflood maximum the concentration decreased to a minimum value of 60 mu g 1 super(-1) in mid-July. Particulate matter in the Kalix River is dominated by Fe which ranges between 14% and 38% of the ashed suspended load, similar to 70-80% of the total Fe load being retained by 0.45- mu m filters. Approximately 10% of particulate Fe can be accounted for by a detrital phase. The particulate Fe/Al ratio showed a mean value of 6.5 which is more than ten times the ratio in mean world river. Particulate Fe showed a peak during early snowmelt and decreased during maximum discharge similar to dissolved Fe. Dissolved Mn concentrations ranged from 1.1 to 53.4 mu m 1 super(-1) with a mean value of 11.2 plus or minus 12.4 mu g 1 super(-1), whereas particulate Mn ranged from 3.1 ti 18.2 mu g 1 super(-1), with a mean concentration of 10.6 plus or minus 4.9 mu g 1 super(-1). During May and June most Mn was transported in the dissolved phase whereas in July and August the particulate fraction dominated. There was a drastic increase in non-detrital particulate Mn with a concomitant decrease in the dissolved fraction in early July with peak values in mid-July and early August. The decrease in dissolved Mn and increase of particulate Mn is probably the consequence of two processes, namely addition of non-detrital particulate Mn to the river, possibly from lakes, and transformation of dissolved Mn to a particulate phase within the river. A combination of increased pH, temperature and particulate Mn triggered the precipitation of dissolved Mn, although the significance of each factor can not be evaluated from this study.
16.	Romer, Rolf L., et al. (författare) Geochronologic significance of lead lines from old cratons 1997 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 136:1-2, s. 125-133 Tidskriftsartikel (refereegranskat)abstract Lead isotope data from geologically mixed suites of Archaean gneisses often yield secondary isochrons that have statistically better fits than might be expected from the geological constraints on the range of samples used. Accepted as true isochrons, these Pb-Pb lines are commonly used both to determine the age of the rock suite and as evidence that all the rocks that yield data points within error of the isochron were formed at the same time from the same source. Using within geologically reasonable limits random data for initial lead and secondary lead growth, we demonstrate that heterogeneous sample sets may yield statistically valid secondary isochrons. This implies that the fit to a common secondary isochron does not necessarily mean that the samples used have the same age or an isotopically similar source. Numerical modelling of artificial data sets suggests that high correlation between mu (sub 1) and mu (sub 2) values is the single most important factor that enhances the statistical fit of the samples about a lead line and smoothes the initial scatter. In contrast, initial scatter will be preserved in data sets with a random relation between mu (sub 1) and mu (sub 2) values. The mu (sub 1) value estimated from the lead line will be biased towards the sample with the lowest mu (sub 2) value.
17.	Routh, Joyanto, 1968-, et al. (författare) Trace-element geochemistry of Onion Creek near Van Stone lead-zinc mine (Washington, USA) — Chemical analysis and geochemical modeling 1996 Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 133:1, s. 211-224 Tidskriftsartikel (refereegranskat)abstract Van Stone lead-zinc mine in Washington is a possible contamination source of Columbia River water. Breaching of an old tailings pond, seepage of contaminated water, and surficial transport of mine tailings have increased trace-element (TE) concentrations in the Onion Creek water and sediments. Chemical analyses of water and sediment samples indicate high TE levels near the breached tailings pond. TE contamination indices for sediments indicate high values of Pb, Zn, and other TE’s which decrease downstream. High Kd values (> 104) for several TE’s (e.g., Al, Cd, Fe, Mn, Pb, V, and Zn) suggest their enrichment in the solid phase. TE concentrations in Onion Creek water and sediment sharply attenuate downstream due to: (1) enhanced carbonate dissolution, thereby increasing pH and immobilizing TE’s; (2) sorption to oxides; and (3) change in lithology from carbonate to granite. Speciation model MINTEQA2 was used to study the effect on TE dispersion due to dissolution-precipitation reactions and adsorption to ferrihydrite. In addition to the field and chemical data, the model also supports the hypothesis that Onion Creek sediments are the major sink for TE’s at VSM. Model runs indicate precipitation of Al, Ba, Ca, Fe, Mg, and Mn minerals from oversaturation, whereas TE’s with low concentrations (Cr, Cu, Ni, Se) or geochemically more mobile (As, Mo, Sb) remain dissolved in water. Near the tailings ponds, high pH and abundance of sorption sites in sediments contribute to the complete adsorption of Pb and Zn species. Because ambient conditions result in the sorption of most Pb and Zn ions, Onion Creek water quality meets EPA regulatory standards. These species will persist in Onion Creek sediments as sorbed or insoluble complexes, and without drastic pH changes (< 4.0) they will remain immobilized. However, continued TE enrichment in sediments will prove hazardous to filter feeding and aquatic organisms.
18.	Skiöld, Torbjörn, et al. (författare) Chemistry of Proterozoic orogenic processes at a continental margin in northern Sweden 1988 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 69:3-4, s. 193-207 Tidskriftsartikel (refereegranskat)abstract Sm-Nd isotopic, major-, trace- and rare-earth-element data for two separate age groups of plutonic rocks have been used to characterize early Proterozoic crust formation mechanisms in the vicinity of the exposed Archaean of northern Sweden. The granitoid rocks of the older (1.89-1.87 Ga) group show calc-alkaline trends (diorite-quartz monzonite-adamellite) and have negative εNd-values ranging from about -8 to -5. They represent variable contamination of isotopically juvenile mantle melts with Archaean crustal material. The younger (1.80 Ga) group of plutonic rocks are of true granitic composition. They show a restricted range of εNd-values which is encompassed by those of the older group. Trace- and major-element data are consistent with the derivation of the younger group of rocks by remobilization of the earlier formed Proterozoic continental crust. This is in contrast to the temporally similar but isotopically more juvenile granitoids of the Skellefte district to the south.
19.	Widerlund, Anders, et al. (författare) Early diagenesis of arsenic in sediments of the Kalix River estuary, northern Sweden 1995 Ingår i: Chemical Geology. - 0009-2541 .- 1872-6836. ; 125:3-4, s. 185-196 Tidskriftsartikel (refereegranskat)abstract Solid-phase As, Fe, Mn, S and Al and pore-water total As, Fe, Mn and S have been determined for two cores from the Kalix River estuary. At the same station, the depositional flux of arsenic was measured sediment traps. Fe(III)-oxides persist in the anoxic zone of the sediment and act as a carrier for arsenic down to depths of 10-15 cm. The release of arsenic into the pore water is controlled by the reduction/dissolution of these oxides. As a result, internal cycling of arsenic, i.e. upward diffusion in pore water, re-adsorption onto Fe(III)-oxides in the oxidized surface layer and reburial occurs in the uppermost 10-15 cm. At the base of the arsenic cycling zone, solid-phase arsenic maxima (160-170 μg g-1) of probable diagenetic origin occur. The quantity of arsenic diffusing back towards the oxidized surface layer (2.2 μg cm-2 yr-1 As) is close to 75% of the quantity of arsenic being deposited due to sedimentation (2.9 μg cm-2 yr-1 As). However, a mass balance for the surface layer indicates that re-adsorption of arsenic onto Fe(III)-oxides may effectively prevent diffusion of dissolved arsenic back into the overlying water column. It is concluded that the interpretation of sedimentary arsenic profiles may be severely complicated due to post-depositional migration of arsenic
20.	Öhlander, Björn (författare) Geochemical characteristics of granites associated with Proterozoic molybdenite mineralization in northern Sweden 1985 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 51:3-4, s. 247-263 Tidskriftsartikel (refereegranskat)abstract Proterozoic molybdenite occurrences in northern Sweden are associated with small plutons of intrusive character located in supracrustal belts whereas large granite areas are barren. In this study, 152 samples of granites associated with molybdenite mineralization, mineralized aplites, granites not known to be associated with molybdenite occurrences but located in supracrustal belts and granites from the large granite areas have been analysed for major elements and the selected trace elements Mo, Sn, Be, Ba, Rb, Sr, Cu, Zn, Zr, V, Y, Nb, F, Cl and S. The study showed that major-element geochemistry and modal composition are not useful for distinguishing between potentially molybdenite-mineralizing and barren granites in northern Sweden. Enriched contents of Sn, Be, Y, Rb and F are most useful for identifying ore-associated granites in the supracrustal belts. The granites from the large granite areas have very low contents of Sn, Mo, Be, Nb, Y, F, Cl and S. It is proposed that the granites associated with molybdenite occurrences were probably generated by partial melting of earlier igneous rocks, or they may be of subcrustal origin, the large granite bodies originated by partial melting of Archean continental crust.
21.	Öhlander, Björn, et al. (författare) Geochemistry of the Proterozoic wolframite-bearing greisen veins and the associated granite at Rostberget, northern Sweden 1989 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 78:2, s. 135-150 Tidskriftsartikel (refereegranskat)abstract At Rostberget in northern Sweden, a swarm of thin, undeformed wolframite-bearing greisen veins occurs within the 1.78-Ga-old Joran granite intrusion. This is a microcline-rich porphyritic granite probably generated with sediments as important source materials. When the Joran granite crystallized, an aqueous fluid, rich in volatiles and W, was active in the central and apical parts of the intrusion. This fluid escaped through fractures caused by tectonic rupturing, the immediate surroundings of the fractures became altered, and the greisen veins were formed. The contents of SiO2, Na2O, Sr, V, Zr and LREE decreased during this greisenization, while the contents of Fe2O3, MnO, MgO, CaO, H2O, W, Sn, Mo, Cu, Rb, Sc, Pb, Be, Nb, HREE and probably Ag increased. K2O, TiO2, P2O5, Ba, Zn and Y were not immobile, but no consistent trends of gain or loss were found. Neutralization of the acid vapour by alteration reactions was probably important for controlling the precipitation of wolframite. Accessory minerals contain most of the REE in all sample types. The gain of HREE during the greisenization was caused mainly by deposition of fluorite (and xenotime), and the loss of LREE was the result of dissolution of monazite (and allanite). No change in Eu content was observed. The enrichment of HREE and the presence of fluorite and minor topaz, indicate alteration from a F-rich fluid, but do not necessarily imply that W was transported as F− complexes.
22.	Ahmed, Engy, et al. (författare) Microbe-mineral interactions : The impact of surface attachment on mineral weathering and element selectivity by microorganisms 2015 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 403, s. 13-23 Tidskriftsartikel (refereegranskat)abstract One of the major gaps within the field of biogeochemistry is the lack of a detailed and deep understanding of the mechanismbehind the microbial inducement of mineral dissolution. The association of microorganisms with the mineral surfaces is an important issue for understanding processes like mineral weathering, biomineralization, bioremediation and biofouling. The present study aims to investigate the performance of attached and unattached soil fungal and bacterial species in biotite weathering and in the selectivity of elements from biotite. Sterilized microplate devices were filled with biotite (>2 mm) followed by an iron limited liquid growth medium and were inoculated separately with six different microbial species isolated from podzol soil: Erwinia amylovora, Pseudomonas stutzeri, Pseudomonas mendocina, Streptomyces pilosus, Neurospora crassa and Penicillium melinii. The experiment was designed in two set-ups: 1) attached form, in which the microorganisms were inoculated directly to the biotite surface, and 2) unattached form, in which 0.4 mu m PET track etched devices were used to separate the microbial cells from the biotite surface. Our findings indicate that the surface attached microorganisms led to a greater dissolution of elements from biotite than the unattached microorganisms that was evidenced by 1) higher dissolution of Fe, Al and Si, 2) greater decrease in pH of the liquid growth medium, and 3) relatively higher production of siderophores. Furthermore, there was no significant difference in the capability of element selectivity between the attached and unattached microbial forms. The biotite dissolution was promoted initially by complexation processes and later by acidification processes for most of the attached and unattached microorganisms. Thus, we conclude that despite the mineral dissolution induced by microbial attachment on the mineral surface, the element composition of the biotite and nutritional need of the microorganisms were the main factors affecting the element selectivity.
23.	Amelin, Yuri, et al. (författare) Isotopic analysis of potassium by total evaporation and incipient emission thermal ionisation mass spectrometry 2021 Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 559 Tidskriftsartikel (refereegranskat)abstract The isotopic compositions of the natural potassium chloride sample NIST SRM 999b, and the isotopically enriched material GSC K-40 that is used in an ongoing study of the half-life of K-40 by decay counting, were determined using total evaporation thermal ionisation mass spectrometry (TE-TIMS) and incipient emission thermal ionisation mass spectrometry (IE-TIMS). Both methods were comprehensively calibrated for precision and accuracy by multiple analyses against gravimetrically prepared synthetic mixtures of enriched K-39 and K-41. These mixtures of enriched isotopic materials characterised for purity and stoichiometry, have K-41/K-39 with uncertainty of ca. 0.02%, and can be used for calibration of either TIMS or MC-ICPMS (multi-collector inductively coupled plasma mass spectrometry) measurements of K isotopic composition independently of the currently accepted IUPAC value. The TE-TIMS and IE-TIMS analyses of potassium using some, but not all, combinations of loading medium, filament configuration, and data processing methods can yield accurate "absolute" isotopic compositions without standardisation. The K-41/K-39 ratio in NIST SRM 999b determined in this study with TE-TIMS and IE-TIMS has the value of K-41/K-39 = 0.072247 +/- 0.000086, 95% confidence level), which is consistent within 95% confidence limits with the isotopic composition of this material derived from the calibration of Garner et al. (1975), which serves as the basis of the current IUPAC recommendation and is used as a reference in the rapidly growing field of potassium stable isotope geochemistry. The isotopic abundance of K-40 in the enriched GSC K-40 is determined with the total uncertainty of 0.075% (95% confidence level), and is suitable for precise calculation of the half-life of K-40 in our ongoing decay counting study.
24.	Augusti, Angela, et al. (författare) Deriving correlated climate and physiological signals from deuterium isotopomers in tree rings 2008 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 252:1-2, s. 1-8 Tidskriftsartikel (refereegranskat)abstract he deuterium (D) abundance of tree-ring cellulose archives past climatic conditions, but previous attempts to access this archive have led to conflicting results. Based on an overview of D fractionation mechanisms in plants, we explain why past measurements of D abundance yield unreliable paleo signals. Our data show that variation in D abundance among the C–H groups (isotopomer variation) of tree-ring cellulose is generally greater than variation in D abundance due to climatic influences. A comparison of the D isotopomer abundances of soluble sugars of annual plants and of trees, and of tree-ring cellulose shows that an “isotopomer pattern” of the C3 photosynthetic pathway is transmitted from soluble sugars to tree-ring cellulose. Differences in this pattern between oaks and conifers appear to be related to differences in metabolism. Furthermore, the patterns are modified by hydrogen isotope exchange between C–H groups and source water during cellulose synthesis. Based on these results, we propose a strategy to simultaneously reconstruct climate signals and signals related to tree physiology from D isotopomers of tree rings. Combination of climate signals and physiological signals may allow the detection of century-time-scale adaptations of trees to past environmental change, and help to forecast future adaptations.
25.	Barker, Abigail, et al. (författare) Insights into the behaviour of sulphur in mid-ocean ridge axial hydrothermal systems from the composition of the sheeted dyke complex at Pito Deep 2010 Ingår i: Chemical Geology. - : Elsevier BV. - 0009-2541 .- 1872-6836. ; 275:1-2, s. 105-115 Tidskriftsartikel (refereegranskat)abstract The behaviour of seawater sulphate in hydrothermal systems at intermediate- to fast-spreading ridges is investigated using new analyses of the δ34S, sulphur concentration and Fe2O3/Fe2O3total, combined with existing 87Sr/86Sr, of sheeted dykes from the Pito Deep tectonic window. The Pito Deep sheeted dyke complex has a similar composition to the sheeted dykes drilled at ODP Hole 504B suggesting that the measured compositions are representative of sheeted dyke complexes at intermediate- to fast-spreading ridges. The dykes show only small increases in δ34S which, combined with the rock dominated δ34S of vent fluids, requires the majority of seawater sulphate to be precipitated as anhydrite before the fluid reacts with the sheeted dyke complex. This loss of sulphate from the fluid means that a much higher Fe2O3 in the sheeted dyke complex than in fresh MORB glasses cannot be explained by oxidation due to seawater sulphate reduction during fluid-rock reaction. Instead, oxidation probably occurs due to degassing of reduced species, largely H2, during dyke emplacement and solidification. A mass balance model that accounts for anhydrite precipitation and Sr partitioning into the anhydrite, as well as fitting the concentration and isotopic ratios of S and Sr in the sheeted dykes and vent fluids, suggests water/rock ratios of -1. For a 1km thick sheeted dyke complex this is equivalent to a fluid flux of ~3×106kgm-2, sufficient to remove ~60% of the latent heat of crystallization from the lower crust.

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