bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicate weathering in anoxic marine sediments
Authors: Wallmann K. , Aloisi G. , Haeckel M. , Tishchenko P. , Pavlova G. , Greinert J. , Kutterolf S. , Eisenhauer A.
Published: August 2008

Two sediment cores retrieved at the northern slope of Sakhalin Island, Sea of Okhotsk, were analysed for biogenic opal, organic carbon, carbonate, sulphur, major element concentrations, mineral contents and dissolved substances including nutrients, sulphate, methane, major cations, humic substances and total alkalinity. Down-core trends in mineral abundance suggest that plagioclase feldspars and other reactive silicate phases (olivine, pyroxene, volcanic ash) are transformed into smectite in the methanogenic sediment sections. The element ratios Na/Al, Mg/Al and Ca/Al in the solid phase decrease with sediment depth indicating a loss of mobile cations with depth and producing a significant down-core increase in the chemical index of alteration.
Ecotoxicity of Ni in soil
Authors: Allen H. E. , Yanqing Lin , Di Toro D. M.
Published: August 2008

Assessing metal contamination of soils has been a difficult task because the metal concentration in soil is not directly correlated to its potential effects. We review an approach, termed the Terrestrial Biotic Ligand Model (TBLM), in which partitioning of metal from soil to soil solution is modelled and the metal in solution interacts with an organism, the biotic ligand, to cause toxicity. The toxicity is modulated by other cations in the soil solution, principally H+, Ca2+, and Mg2+. New results for the model using Ni as the toxic species and barley root elongation as the biological response are presented.
Geochemical characteristics of rare earth element movement during incipient alteration of pyroxenes in Guatemalan corestones
Authors: Donatelle A. , Velbel M.
Published: August 2008

Earth scientists currently use changes in major and minor elements as an indication of rock alteration. Work on spheroidal weathering has shown an increase in the rare earth element (REE) whole-rock abundancescan accompany minor changes in major elementsand highlights the need for new, more sensitive, geochemical techniques of detecting incipient alteration. Augites from the core and rind of a corestone system from the Tecuamburro complex in SE Guatemala are examined to determine their role in the whole-rock REE increases.
Reactive nanoparticles in chalk: implications for sequestration of metals from groundwater
Authors: Balogh Z. , Stipp S. L. S. , Bechgaard K. , Johnson E.
Published: August 2008

Water supplies from chalk aquifers in northern Europe can be contaminated by semi-metals such as As and metals such as Cr, Ni and many more, as a result of leaks from landfills, industrial sites and from natural oxidation of pyrite in the chalk, releasing trace elements. Chalk, which is predominantly calcite (CaCO3), has the ability to immobilize Ni, but its uptake by chalk is sometimes greater than expected. In an attempt to identify the controls on metal uptake, chalk samples from Klintholm I/S (Fyn, Denmark) were decalcified in EDTA solution and the residue was examined with transmission electron microscopy (TEM) for morphology and composition. Energy dispersive X-ray spectrometry (EDXS) revealed minor Si and Al (probably clay) and major Mn and Fe as (hydr)oxides. These natural nanoparticles have very large surface areas contributing to chalk’s uptake capacity for Ni and other metals from groundwater.
Experimental study of Ni adsorption on chalk: preliminary results
Authors: Belova D. A. , Lakshtanov L. Z. , Stipp S. L. S.
Published: August 2008

Nickel can cause allergic reactions so it is often considered to be a toxic metal. In some areas of Denmark and northern Europe, where drinking water comes predominantly from chalk aquifers, Ni concentrations in groundwater are higher than safety limits. The contamination is natural in the sense that it comes from oxidation of small grains of pyrite in the chalk that contain Ni as a trace element (Larsen and Postma, 1997). Because of Danish water-treatment practice, the most politically acceptable water-supply protocol is not to use secondary water treatment, so in order to minimize allergy risks for consumers, high-Ni water is either mixed with low-Ni water to bring concentrations below the Danish limit, or new, uncontaminated wells are drilled. Some recent efforts focused on finding a method to minimize nickel concentration while the water is still in the ground, before it is pumped to the primary treatment facility and distributed.

Unfortunately, only a few experimental studies of the interactions between Ni and calcite have been published (Lakshtanov and Stipp, 2007; Zachara et al., 1991; Hoffmann and Stipp, 2001) and we found no previous work on Ni uptake by chalk. Experiments with calcite show that Ni forms surface complexes and it is incorporated into the solid as solid solution. Chalk aquifers often contain as much as 99% calcite, so the same processes ought to control Ni uptake, but some very preliminary experiments suggested that chalk behaviour might not be what one would expect by analogy with calcite (Stipp et al., 2005). The aim of this study was to examine the Ni-uptake capacity of chalk and compare it with that of synthetic, pure calcite.
The effect of aqueous sulphate on basaltic glass dissolution rates
Authors: Flaathen T. K. , Oelkers E. H. , Gislason S.
Published: August 2008

Steady-state dissolution rates of basaltic glass were measured in mixed-flow reactors at 50ºC at pH 3 and 4 as a function of aqueous sulphate concentration. Dissolution rates in the presence of 0.1 moles/kg SO42- were found to be ~3 times greater than those in corresponding SO42- free solutions. This rate increase is found to be approximately consistent with that calculated using a rate equation previously proposed by Gislason and Oelkers (2003). These results suggest that the addition of sulphate to injected CO2 may facilitate CO2 sequestration in basalts by accelerating basaltic glass dissolution rates thus more rapidly releasing aqueous Ca and Mg to solution.
Influence of biofilms on transport of fluids in subsurface granitic environments — some mineralogical and petrographical observations of materials from column experiments
Authors: Coombs P. , West J. M. , Wagner D. , Turner G. , Noy D. J. , Milodowski A. E. , Lacinska A. , Harrison H. , Bateman K.
Published: August 2008

Landfill and radioactive waste disposal risk assessments focus on contaminant transport and are principally concerned with understanding the movement of gas, water and solutes through engineered barriers and naturalgroundwater systems. However, microbiologicalactivity can impact on transport processes changing the chemicaland physicalcharacteristics of the subsurface environment. Such effects are generally caused by biofilms attached to rock surfaces. This paper will present some mineralogical and petrographical observations of materials extracted at the completion of an experimental column study which examined the influences of biofilm growth on groundwater flow through crushed diorite from the Äspö Hard Rock Underground Research Laboratory, Sweden.
Chemistry and FT-IR spectroscopic studies of plants from contaminated mining sites in the Iberian Pyrite Belt, Portugal
Authors: Durães N. , Bobos I. , Ferreira da Silva E.
Published: August 2008

Semi-aquatic and native plants collected from a mining site in the Iberian Pyrite Belt were analysed. Semi-aquatic plants showed enrichment of Cu (1.2—11 times), Zn (1.3—6 times), Pb (5—8 times) and As (24—1300 times) relative to typical concentrations in plants of the same species growing at uncontaminated sites. Translocation factors indicate limited internal metal transportation from roots to shoots. Infrared spectroscopy identified aromatic and aliphatic C-H (CH2) groups, S-O complexes and kaolinite in semi-aquatic plants.
Natural and anthropogenic impacts on the composition of lake sediments
Authors: Eskola T. , Peuraniemi V.
Published: August 2008

Lake sediments were studied from four lakes in environmentally different areas in northern Finland. Lakes Pyykösjärvi and Kuivasjärvi are situated near roads with heavy traffic and the city of Oulu. Lakes Martinlampi and Umpilampi are small lakes in a forest area with no immediate human impact nearby. The concentration of Pb increases in the upper parts of the sedimentary columns of Lake Kuivasjärvi and Lake Pyykösjärvi. This is interpreted as being an anthropogenic effect related to heavy traffic in the area and use of Lake Pyykösjärvi as an airport during World War II. High Ni and Zn concentrations in the Lake Umpilampi sediments are caused by weathered black schists. Sediments in Lake Martinlampi show high Pb and Zn contents with increasing Pb concentrations up through the sedimentary column. The sources of these elements are probably Pb-Zn mineralization in the bedrock, Pb-Zn-rich boulders and anomalous Pb and Zn contents in till in the catchment area of the lake.
The adsorption of progesterone onto mineral surfaces imaged with high-resolution atomic force microscopy
Authors: Goritschnig B. , Hallam K. R. , McMaster T. , Ragnarsdottir V.
Published: August 2008

Atomic force microscopy (AFM) has been used to monitor the appearance and behaviour of the hormone progesterone on mineral surfaces, including mica and highly oriented pyrolytic graphite (HOPG). Different solvents have been used resulting in various features on the two substrates. After the application of 254 nm ultra-violet (UV) light, changes in structure of the adsorbed hormone have been observed. To understand the reactions at the progesterone-mica interface in aqueous solution, adsorption has been studied in situ with AFM.
Geochemistry of arsenic (As) in spring and stream waters from San Antonio de los Cobres, NW Argentina
Authors: Hudson-Edwards K. A. , Archer J.
Published: August 2008

Spring and stream waters from the San Antonio de los Cobres area in NW Argentina have high concentrations of arsenic (As) (151—9490 μg l-1), of which AsV varies widely (6—~100% of total As). Arsenic concentrations correlate with Na, K, Cl, HCO3, B and Li, which are high in the spring waters and are typical of geothermal areas world-wide. Springs near San Antonio supply large amounts of As to the Rio San Antonio de los Cobres (up to 1180 μg l-1), but these concentrations decline to 400 μg l-1 within 10 km of the spring inputs, due to dilution and mineral precipitation.
Efficiences of As uptake from aqueous solution by a natural vivianite material at 4ºC
Authors: Hudson-Edwards K. A. , Houghton S. , Taylor K. G.
Published: August 2008

Several field and laboratory studies have demonstrated that secondary Fe-bearing minerals such as goethite, lepidocrocite and mackinawite have a high capacity for the uptake of As, but little work has been carried out to examine the capacity of the mineral vivianite [Fe3(PO4)2·8H2O] for this element. We report here preliminary results of an experimental study designed to test the efficiency of As(III) and As(V) uptake by natural vivianite at acid, near-neutral and alkaline pH at T = 4ºC, which is representative of Lake Baikal-type environments, where natural vivianite is reported to occur. The vivianite takes up between 0 and 5% As(III), and between 21 and 45% As(V), from 200 ppb solutions of these As species. Further work at 25ºC and other solution concentrations, together with characterization of the post-sorption solids, will yield information on the efficiencies and mechanisms of As uptake by natural vivianite.
Detection of coal combustion products in stream sediments by chemical analysis and magnetic-susceptibility measurements
Authors: Frančišković S.
Published: August 2008

Coal slag and ash, obtained from burning coal in a textile factory in Duga Resa (Croatia) was discharged directly into the Mrežnica River for 110 y (1884–1994), from where it travelled to the Korana River and further to the Kupa River at Karlovac, a total of ~50km from its source. Of 54 elements determined by inductively coupled plasma mass spectrometry (ICP-MS) in the <2 mm sediment fraction, a number of anomalously high levels were recorded. The geoaccumulation index (Igeo) for the anomalous elements were: Hg (1.88), B (4.05), Na (1.44), Al (2.05), V (1.65), Cr (1.20), Fe (1.18), Ni (2.10), Cu (2.37), Sr (0.97), Zr (3.27), Mo (3.34) and U (4.03). Low-field magnetic susceptibility (MS) was measured for each sample. The Igeo for MS in the anomalous region is 5.85. Correlation analysis showed good correlation (>0.90) of MS with: B (0.96), U (0.95), Zr (0.94), Sr (0.93), Na (0.92), Mo (0.92) and Ni (0.90). Cluster analysis of R-modality indicates that MS is linked to B, Mo, Na and U. Low correlation of MS with Fe (0.36) suggests that Fe in stream sediments is not in a ferromagnetic form. Neither maghemite, nor magnetite phases were identified by X-ray diffraction (XRD) in the sediments. Low-field magnetic susceptibility provides an indicator of contamination of river sediments by transported coal slag and ash, although it cannot be prescribed to a single element.
Crystallization of the (Cd,Ca)CO3 solid solution in double diffusion systems: the partitioning behaviour of Cd2+ in calcite at different supersaturation rates
Authors: Katsikopoulos D. , Fernandez-Gonzalez Á. , Prieto M.
Published: August 2008

Considering an ideal solid solution, the partitioning of cadmium in calcite was studied at different levels of supersaturation (δ) using counter-diffusion experiments. The effective (non-equilibrium) distribution coefficients of Cd2+ in calcite (DCd), varied between 20 and 100 depending on the initial concentration of reactants and the evolution of supersaturation. A function that relates the DCd with the supersaturation at nucleation was derived: logDCd= —0.40logδ + 2.42. The relationship obtained suggests that in naturalwaters, Cd2+ can be incorporated to a greater degree in calcite when the solid solution-aqueous solutions system is near to equilibrium, which can occur in scenarios where the supersaturation rate and hence the supersaturation level are relatively small.
The geochemical and isotopic composition of ground waters in West Bengal: tracing ground-surface water interaction and its role in arsenic release
Authors: Lawson M. , Ballentine C. J. , Polya D. A. , Boyce A. J. , Mondal D. , Chatterjee D. , Majumder S. , Biswas A.
Published: August 2008

In many areas of south and south-eastern Asia, concentrations of As in ground water have been found to exceed the WHO maximum concentration limit of 10 μg/l. This is adversely affecting the health of millions of people and has grave current and future health implications. It has recently been suggested that extensive abstraction of ground water in these areas may accelerate the release of As to ground water. This study uses geochemical and isotopic data to assess this hypothesis. The area investigated in this study is in the Chakdaha block of the Nadia District, West Bengal. The ground water is predominantly of the Ca-Mg-HCO3 type, although some samples were found to contain elevated concentrations of Na, Cl and SO4. This is thought to reflect a greater degree of water-rock interaction at the locations of these particular samples. Arsenic concentrations exceeded the national limit of 50 μg/l in 13 of the 22 samples collected. Four of the 13 samples with high As were recovered from tubewells with depths of 60 m or more. Shallow ground water samples were found to have a stable isotopic composition which falls subparallel to the Global Meteoric Water Line. This probably represents a contribution of evaporated surface water to the ground water, possibly from surface ponds or re-infiltrating irrigation water. Deep ground water, conversely, was shown to have a composition that closely reflects that of meteoric water. The data presented in this study suggest that, whilst the drawdown of surface waters may drive As release in shallow ground waters, it is not responsible for driving As release in deep ground water. However, local abstraction may have resulted in changes in the ground water flow regime of the area, with contaminated shallow ground waters being drawn into previously uncontaminated deep aquifers.
Contamination level and distribution patterns of Hg in soil, sediment, dust and sludge from various anthropogenic sources in Korea
Authors: Lee Ko Eun , Chon Hyo Taek , Jung Myung Chae
Published: August 2008

In spite of significant concerns about Hg contamination and its toxic impacts in the environment, limited studies have been carried out in Korea. The objectives of this study are to investigate the extent and degree of Hg contamination in soil, sediment, dust and sludge from various anthropogenic sources in Korea, and to understand the distribution patterns of Hg in the study areas. The anthropogenic sources of Hg contamination were divided into four major sources: (1) by-product from abandoned Au-Ag mines; (2) coal combustion; (3) cement production; and (4) industrial and domestic discharges. A calculation of enrichment factor and index of geoaccumulation for Hg in soils and sediments indicated that some samples from mining sites were enriched in Hg. In addition, Hg concentrations in marine sediments from industrial sites were above the Effects Range Median (ERM) criteria suggested by the National Oceanic and Atmospheric Administration of the United States (NOAA). Therefore, it can be concluded that samples from various sites were directly influenced by anthropogenic sources of Hg in the surface environment.
Spectrophotometric determination of low-level concentrations of Se in aqueous solutions
Authors: Matamoros A. , Benning L. G.
Published: August 2008

This paper describes the design, testing and validation of a simple and inexpensive spectrophotometric method for total Se analysis in aqueous solution based on the azo coupling reaction of amines. In this reaction, selenite ions react with hydroxylamine hydrochloride (NH2OH.HCl), which in turn diazotizes p-Nitroaniline and is coupled with N-1-naphthyl-ethylenediamine dihydrochloride (NEDA) to form a red coloured azo compound. This azo compound has a maximum absorption peak at 545 nm, an apparent molar absorption of 2.85x104 l mol-1 cm-1 and it follows the Beer’s law in the range from 0.01 to 2.50 mg/l with R2 = 0.9998. Interferences between the azo reaction and non-targeted ions often present in environmental samples (i.e., NO3-, CO3-, Cl- or metals) were investigated and specific protocols to overcome them were implemented. The advantages of the new method for low levels of Se in aqueous solutions are its high sensitivity and reproducibility, and the fact that measurements are simple, rapid and low-cost.
A record of anthropogenic Pb deposition in a Mediterranean karst catchment (Lake Vrana, Cres Island, Croatia)
Authors: Miko S. , Mesić S. , Šparica Miko M. , Hasan O.
Published: August 2008

To trace the historyof anthropogenic, atmospheric Pb pollution, analyses of soils from the region and of cores from the karst Lake Vrana (Croat: Vransko jezero) on the island of Cres were performed. The area affected byPb pollution in Croatia covers most of the high-mountain karst region. Since lake sediments can act as archives of atmospheric deposition of metals (and other pollutants) a multi-element analysis as well as Pb isotopes of dated sediment core samples and palaeosoil from the catchment enabled the evaluation of Pb-pollution history. The Pb/Sc ratios and the 206Pb/207Pb ratios allowed the calculation of enrichment factors and the anthropogenic contributions of Pb during the past 4000 y. The sediments of Lake Vrana were found to be a consistent record of Pb pollution in this part of the Mediterranean region, despite the fact that the catchment lost most of its soil cover between 1404 and 1650 AD due to deforestation which caused a major change in sediment composition.
Multiple regression analysis of As ground-water hazard and assessment of As-attributable human health risks in Chakdha Block,West Bengal
Authors: Mondal D. , Hegan A. , Rodriguez-Lado L. , Banerjee M. , Giri A. K. , Polya D. A.
Published: August 2008

Soluble inorganic As is toxic with both cancer and non-cancer endpoints. Of the 80 million people in West Bengal, 50 million are living in the nine As-affected districts with millions at risk from using water for drinking, cooking or irrigation (Chakraborti et al., 2004). An environmental tragedy is developing in West Bengal with an alarming number of cases of skin lesions (Guha Mazumder et al., 1998; Mukherjee et al., 2005), respiratory symptoms (von Ehrenstein et al., 2005), adverse pregnancy outcomes and infant mortality (von Ehrenstein et al., 2006) and neurological complications (Mukherjee et al., 2005) associated with ingestion of As-contaminated water.
Impact of acid mine drainage from Tinoca Mine on the Abrilongo dam (southeast Portugal)
Authors: Morais C. , Rosado L. , Mirão J. , Pinto A. P. , Nogueira P. , Candeias A. E.
Published: August 2008

This work presents a geochemical study conducted on the abandoned Tinoca Copper mine (southeast Portugal) to evaluate the potential hazard in surrounding areas particularly the effect on the Abrilongo River Dam which receivesthe acid waters from the mine watershed. The characterization of the area was performed over a period of 3 y and involved the study of waters, sediments and mine wastes. A sequential extraction methodology was conducted on the sediments and mine wastes and five elements were selected (Cu, Fe, Zn, Cd and Pb). The statistical and spatial analysis allowed the inference of the affinities between the chemical elements and specific mineralogical phases and to characterize chemical behaviour such as mobility and bioavailability. The results show that the distance to the source (mine-waste deposit), the point of zero charge, and the dynamics of the system are factors that control the behaviour of the elementss tudied. The acid drainage is characterized by an average pH of 2.5 and concentrationsof copper 20 timesgreater than the legal limit for irrigation waters.
Inorganic substances screening and prioritization (ISSP) in risk assessment for mining operations
Authors: Pan J. , Oates C. , Ihlenfeld C. , Plant J. , Voulvoulis N.
Published: August 2008

Metals have been central to the development of human civilization from the Bronze Age to the present although historically, mining and smelting have been the cause of local environmental pollution with the potential to harm human health. Despite problems from artisanal mining in some developing countries, modern mining for Western standards now uses the best available mining technology combined with environmental monitoring, mitigation and remediation measures to control emissions to the environment. The relocation and removal of large quantities of mineral and waste could also release chemicals into the environment including surface water, ground water and soil during the mining lifecycle. There are only few published methods available for prioritizing hazardous chemicals. These fail to recognize differences between organic and inorganic chemicals make it necessary to develop separate screening and prioritization procedures for those two different classes of chemicals. In this study, we focus on the development of screening and prioritization procedure in risk assessment for inorganic chemicals with particular reference to those used, generated and released in mining operations.
Magnetic resonance imaging (MRI) of heavy-metal transport and fate in an artificial biofilm
Authors: Phoenix V. R. , Holmes W. M. , Ramanan B.
Published: August 2008

Unlike planktonic systems, reaction rates in biofilms are often limited by mass transport, which controls the rate of supply of contaminants into the biofilm matrix. To help understand this phenomenon, we investigated the potential of magnetic resonance imaging (MRI) to spatially quantify copper transport and fate in biofilms. For this initial study we utilized an artificial biofilm composed of a 50:50 mix of bacteria and agar. MRI successfully mapped Cu2+ uptake into the artificial biofilm by mapping T2 relaxation rates. A calibration protocol was used to convert T2 values into actual copper concentrations. Immobilization rates in the artificial biofilm were slow compared to the rapid equilibration of planktonic systems. Even after 36 h, the copper front had migrated only 3 mm into the artificial biofilm and at this distance from the copper source, concentrations were very low. This slow equilibration is a result of (1) the time it takes copper to diffuse over such distances and (2) the adsorption of copper onto cell surfaces, which further impedes copper diffusion. The success of this trial run indicates MRI could be used to quantitatively map heavy metal transport and immobilization in natural biofilms.
Weathering of S. Domingos (Iberian Pyritic Belt) abandoned mine slags
Authors: Rosado L. , Morais C. , Candeias A. E. , Pinto A. P. , Guimarães F. , Mirão J.
Published: August 2008

The S. Domingos abandoned mine is a major source of pollutant-metals contamination. Slags from the 19th-20th century contain the most hazardous material. However, the release of pollutant metals depends on the metal-retention capability of weathering products. This work shows that Zn is not effectively retained by these weathering products while As and Pb are partially stored in sulphates. Copper, on the other hand, has a different behaviour and is the most leachable of the elements studied.
Can chromite weathering be a source of Cr in soils?
Authors: Garnier J. , Quantin C. , Guimarães E. , Becquer T.
Published: August 2008

At Niquelândia, Cr extracted from the soil (5,000–9,300 mg.kg-1) is likely the result of the Cr-bearing Fe-oxides compared to the Cr-spinels, showing that low Cr-containing minerals present in the dunite (enstatite, olivine and clay minerals) have been completely dissolved. The chromites, accumulated inside soil profiles, have undergone chemical weathering, leading to a Cr enrichment during soil genesis. Traces of dissolution inside the soil chromites suggest that they can be slowly weathered. In this case chromites could represent a diffuse source of available Cr(III) within the soil profiles.
The impact of Eisenia veneta on As, Cu, Pb and Zn uptake by ryegrass (Lolium perenne L.)
Authors: Sizmur T. , Hodson M. E.
Published: August 2008

Earthworms are an essential part of the soil fauna in many global soils, represent a significant proportion of the soil biomass and are regarded as a useful indicator of soil health and quality (Edwards, 2004). They are also often the subject of inoculation programmes during the restoration of degraded lands (Butt, 1999) and the inoculation of earthworms to metal-contaminated soils has been suggested(Dickinson, 2000) largely due to the role earthworms are known to play in soil formation at such sites (Frouz et al., 2007).
Nano-technology and a sustainable environment
Authors: Stipp S. L. S. , Christiansen B. C. , Dideriksen K. , Skovbjerg L.L. , Karlby L. , Lakshtanov L. Z.
Published: August 2008

Nano-technology has a lot to contribute toward efforts for a sustainable environment. In addition to the promise of sensors, monitoring devices and functional particles, there is new, fundamental information to begaine d by applying nm-scale measuring techniques to natural materials. Improved understanding of the interaction of fluids with natural solids can lead us to new solutions for some of society’s problems, especially in the realm of clean water and safe treatment of waste. Ultra-high resolution lets us define the molecular-scale processes responsible for uptake of contaminants such as transition metals (e.g. Ni and Cr), radioactive species (e.g. Np) and organic compounds (e.g. glyphosate, a pesticide), while they adsorb on minerals such as calcite and Fe oxides and in some cases, are immobilized by solid-solution formation. With molecular-level resolution, we can see changes that with our traditional methods would only be visible after years or geological time.
Speciation studies in understanding high As content in ground water
Authors: Szocs T. , I. Horváth  , Bartha A. , Bertalan É. , Ballók M. , Horváth É.
Published: August 2008

Two sites with five wells in the Danube-Tisza interfluvial were studied in order to help understand the genesis of the high-As content of shallow ground water. Separation of As species was carried out in the field as it proved to be the best method by which to preserve the As species. Different geochemical environments could be separated by the speciation studies which correlate with the concentrations of oxyanion-forming elementss uch asV, Se, Mo, U and W.
Mn oxide as a contaminated-land remediation product
Authors: Tourney J. , Dowding C. , Worrall F. , McCann C. , Gray N. , Davenport R. , Johnson K.
Published: August 2008

Natural Mn oxides are an important component of biogeochemical cycles in many environmental settings. Mn oxides are strong oxidizing agents, facilitating the breakdown of organic contaminants and enhancing humification of soil organic matter. Interactions with metals and radionuclides, including surface adsorption, sequestration and oxidation can lead to incorporation of metals into insoluble mineral phases and a consequent reduction in bioavailability of toxic contaminants. Because of these properties, addition of Mn oxides may prove an effective treatment method for land contaminated by a range of organic and inorganic contaminants.
Mapping singularities — a technique to identify potential Cu mineral deposits using sediment geochemical data, an example for Tibet, west China
Authors: Zuo R. , Cheng Q.
Published: August 2008

Geochemical anomalies can be used in mineral resource exploration. We demonstrate a technique for mapping anomalies. The Gangdese mineral district in Tibet, west China was chosen as a study area for identifying geochemical anomalies and predicting Cu mineral resources using sediment geochemical data. The results show that the anomalies are associated both with known deposits in the middle of the study area, but also with E—W and N——E oriented faults in the north of area. These areas should be explored for undiscovered Cu mineral deposits.
Structure and function of siderophores produced by mycorrhizal fungi
Authors: Haselwandter K.
Published: August 2008

Most fungi synthesize siderophores as chelating agents which form soluble complexes with Fe3+ with very high stability constants, thus solubilizing ferric Fe. Ericoid mycorrhizal fungi release ferricrocin or fusigen as the main siderophores. Ferricrocin was also shown to be produced by the ectomycorrhizal fungi, Cenococcum geophilum and Hebeloma crustuliniforme. Arbuscular mycorrhizal fungi are reported to enhance Fe-uptake rates of associated host plants which can be taken as an indication that mycorrhizal siderophores of a yet unknown structure may be involved. Mycorrhizal fungi of orchids were shown to produce as the main siderophores, both well known ferrichrome-type siderophores or the novel linear trishydroxamate basidiochrome.
Geochemical investigation of weathering processes in a forested headwater catchment: mass-balance weathering fluxes
Authors: Jones B. F. , Herman J. S.
Published: August 2008

Geochemical research on natural weathering has often been directed towards explanations of the chemical composition of surface water and ground water resulting from subsurface water-rock interactions. These interactions are often defined as the incongruent dissolution of primary silicates, such as feldspar, producing secondary weathering products, such as clay minerals and oxyhydroxides, and solute fluxes (Meunier and Velde, 1979). The chemical composition of the clay-mineral product is often ignored. However, in earlier investigations, the saprolitic weathering profile at the South Fork Brokenback Run (SFBR) watershed, Shenandoah National Park, Virginia, was characterized extensively in terms of its mineralogical and chemical composition (Piccoli, 1987; Pochatila et al., 2006; Jones et al., 2007) and its basichydrology. O’Brien et al. (1997) attempted to determine the contribution of primary mineral weathering to observed stream chemistry at SFBR. Mass-balance model results, however, could provide only a rough estimate of the weathering reactions because idealized mineral compositions were utilized in the calculations. Making use of detailed information on the mineral occurrence in the regolith, the objective of the present study was to evaluate the effects of compositional variation on mineral-solute mass-balance modelling and to generate plausible quantitative weathering reactions that support both the chemical evolution of the surface water and ground water in the catchment, as well as the mineralogical evolution of the weathering profile.
Effect of cyanobacterial growth on biotite surfaces under laboratory nutrient-limited conditions
Authors: Kapitulčinova D. , Cockell C. S. , Hallam K. R. , Ragnarsdottir K. V.
Published: August 2008

Laboratory experiments with two cyanobacterial strains grown on low-nutrient agar media in the presence of biotite flakes were performed in order to reveal possible mechanisms and rates of cyanobacterial bioweathering. Both cyanobacteria colonized the biotite flakes. Leptolyngbya grew mostly in the biotite interlayers, whereas Hassallia colonized the sides and the topmost surface of the biotite flakes. After a 3-month incubation, rounded features including cyanobacterium-shaped pits were observed on the biotite surface cleared of the organic material. No such features were observed on flakes incubated for 1 month.
Pseudomorphic replacement of single calcium carbonate crystals by polycrystalline apatite
Authors: Kasioptas A. , Perdikouri C. , Putnis C. V. , Putnis A.
Published: August 2008

During chemical weathering and natural hydrothermal reactions, apatite can form by replacing calcium carbonates. In hydrothermal experiments in which aragonite and calcite single crystals have been reacted with phosphate solutions, the carbonates are replaced by polycrystalline hydroxylapatite (HAP). In both cases the crystals have retained their overall morphology while their compositions have changed significantly. The HAP appears to have a crystallographic relationship to the parent carbonate crystals. The textural relationships are consistent with an interface-coupled dissolution-precipitation mechanism. Structural relationships and relative molar volumes and solubilities appear to be factors that greatly affect replacement reactions.
Incongruent weathering of Cd and Zn from mine tailings
Authors: Kossoff D. , Hudson-Edwards K. A. , Dubbin W. E. , Alfredsson M.
Published: August 2008

Weathering ofdischarged mine tailings contaminates streams, rivers and floodplains with toxic metals on a vast scale. The magnitude of the problem depends on input tailings mineralogy, storage and dispersal, and climatic conditions. To better understand the mechanisms of long-term tailings weathering, a leaching column study was established, incorporating tailings and soil from Potosí, Bolivia, with the aim of modelling a 25 year field period. The Zn/Cd molar ratio ofthe tailings leachate water, initially 738 for the unaltered tailings, is highly variable over 15 model years of leaching, particularly in the mixed tailings-soil columns. Columns with soil have ratios as high as 2563, while pure tailings columns reach ratios of <376. We employ complementary techniques, involving atomistic computational modelling, leachate analysis and mineralogical characterization, to elucidate the mechanisms governing these incongruent Cd and Zn weathering dynamics.
Influence of surface-area estimation on rates of plagioclase weathering determined from naturally weathered 3400 y old Hawaiian basalt
Authors: Velbel M. A. , Losiak A. I.
Published: August 2008

Dimensions of plagioclase (An65) crystals in a polished thin section of naturally weathered 3400 y old Hawaiian basalt were measured by scanning electron microscopy (in backscattered electron imaging mode). The three-dimensional shape, size, volume and surface area of the plagioclase crystals were then estimated using the method of Morgan and Jerram (2006). The weathering rate of plagioclase (mass loss divided by initial geometric surface area during 3400 y) is –12.116 log10 mol m–2 s–1. This weathering rate represents a time span (3.4 ka) intermediate between laboratory experimental timescales and the ages of regoliths in field studies of natural weathering rates. Weathering rates of the same plagioclase are recalculated using different assumptions concerning the method of estimating surface area, including simple geometric surface area and geometric surface area adjusted for surface roughness. Varying assumptions about surface area result in variations of up to two orders of magnitude in rates estimated from the same basic crystal geometry. The slowest rate estimated here approaches but does not fall within the range of previously determined field rates of plagioclase weathering.
Polystage apatite recrystallization and svanbergite formation during weathering in an acid karstic environment
Authors: Mordberg L. E. , Stanley C. J. , Antonov A. V.
Published: August 2008

A Devonian weathering profile was developed near the contact of Riphean dolostone containing disseminated carbonate-fluorapatite and intensively pyritized black shales. Samples from the profile were investigated by XRF, SEM, electron microprobe and ion microprobe. Rock-forming minerals are apatite, diaspore, chlorite and kaolinite, while accessory minerals are svanbergite, anatase, pyrite and zircon.

Primary marine carbonate-fluorapatite is represented by extremely weathered crystals concentrated near the footwall. Dissolution of apatite and pyrite provided an acidic environment that is expressed in the formation of S-rich apatite and svanbergite. The environment allowed Ti migration which formed anatase in weathered apatite grains. Coupled substitution Na+ + S6+ = Ca2+ + P5+ is suggested in S-rich apatite. A large volume of dissolved carbonate rocks was a source of Sr necessary for svanbergite formation. Apatite of the third generation formed at the final stage of weathering is represented by small (10—30 μm) very well shaped crystals.
Molecular mechanisms of thrombus formation in ischemic stroke: novel insights and targets for treatment
Authors: Stoll Guido , Kleinschnitz Christoph , Nieswandt Bernhard
Published: August 2008

In ischemic stroke, treatment options are limited. Therapeutic thrombolysis is restricted to the first few hours after stroke, and the utility of current platelet aggregation inhibitors, including GPIIb/IIIa receptor antagonists, and anticoagulants is counterbalanced by the risk of intracerebral bleeding complications. Numerous attempts to establish neuroprotection in ischemic stroke have been unfruitful. Thus, there is strong demand for novel treatment strategies. Major advances have been made in understanding the molecular functions of platelet receptors such as glycoprotein Ib (GPIb) and GPVI and their downstream signaling pathways that allow interference with their function. Inhibition of these receptors in the mouse stroke model of transient middle cerebral artery occlusion prevented infarctions without increasing the risk of intracerebral bleeding. Similarly, it is now clear that the intrinsic coagulation factor XII (FXII) and FXI play a functional role in thrombus formation and stabilization during stroke: their deficiency or blockade protects from cerebral ischemia without overtly affecting hemostasis. Based on the accumulating evidence that thrombus formation and hemostasis are not inevitably linked, new concepts for prevention and treatment of ischemic stroke may eventually emerge without the hazard of severe bleeding complications. This review discusses recent advances related to antithrombotic strategies in experimental stroke research.
Clinical features and treatment outcome of nasal-type NK/T-cell lymphoma of Waldeyer ring
Authors: Li Ye-Xiong , Fang Hui , Liu Qing-Feng , Lu Jiade , Qi Shu-Nan , Wang Hua , Jin Jing , Wang Wei-Hu , Liu Yue-Ping , Song Yong-Wen , Wang Shu-Lian , Liu Xin-Fan , Feng Xiao-Li , Yu Zi-Hao
Published: August 2008

The clinical characteristics and prognosis remain unclear for nasal-type NK/T-cell lymphoma of Waldeyer ring (WR-NKTL). The aim of this study is to determine the clinical features and outcome. Ninety-one patients with WR-NKTL were reviewed. According to the Ann Arbor system, 15, 56, 12, and 8 patients had stage I, II, III, and IV. Of patients with stage I and II, 54 received combined chemotherapy and radiotherapy (CMT), 13 received radiotherapy alone, and 4 patients received chemotherapy alone. All 20 patients with stage III/IV received primary chemotherapy. The disease is characterized by predominance in young males, good performance, a propensity for nodal involvement, frequent stage II through IV diseases, low frequency of elevated LDH, low-risk international prognostic index (IPI), high sensitivity to radiotherapy, and intermediate sensitivity to chemotherapy. The 5-year overall survival and progression-free survival for all patients were 65% and 51%, respectively. The age, B symptoms, stage, and IPI were important prognostic factors. CMT tended to improve the survival compared with radiotherapy alone for patients with stage I and II diseases. Both nodal involvement and distant extranodal dissemination were the primary failure patterns. WR-NKTL appears to have distinct clinical characteristics and favorable outcomes.
A genetic polymorphism of the osteoprotegerin gene is associated with an increased risk of advanced prostate cancer
Authors: Narita Naofumi , Yuasa Takeshi , Tsuchiya Norihiko , Kumazawa Teruaki , Narita Shintaro , Inoue Takamitsu , Ma Zhiyong , Saito Mitsuru , Horikawa Yohei , Satoh Shigeru , Ogawa Osamu , Habuchi Tomonori
Published: August 2008

Background

The purpose of this study was to evaluate the role of osteoprotegerin gene (OPG) polymorphisms as genetic modifiers in the etiology of prostate cancer (PCa) and disease progression.

Methods

Three hundred and sixty one patients with PCa and 195 normal controls were enrolled in the study, and two genetic polymorphisms, 149 T/C and 950 T/C in the putative promoter region of OPG, were genotyped.

Results

There was no significant difference in the genotype frequencies between PCa patients and controls (P = 0.939 and 0.294 for 149 T/C and 950 T/C polymorphisms, respectively). However, those patients with TC and TT genotypes in the 950 T/C polymorphism had a significantly increased risk of extraprostatic (age-adjusted odds ratio; aOR = 1.74 and 2.03 for TC and TT genotypes compared with the CC genotype, P = 0.028) and metastatic disease (aOR = 1.72 and 2.76 for TC and TT genotypes compared with the CC genotype, P = 0.009) compared with those with the CC genotype. In addition, analysis of the metastatic PCa patients (Stage D) showed that the presence of the T allele of the OPG 950 T/C polymorphism was an independent risk factor predicting survival by Cox proportional hazard regression analyses (P = 0.031).

Conclusion

Progression of PCa may be influenced by an intrinsic genetic factor of the host's bone metabolism. The variant C allele of 950 T/C in the OPG promoter may play a major role as a genetic safe guard against progression in patients with PCa.
Malaria morbidity in Papua Indonesia, an area with multidrug resistant Plasmodium vivax and Plasmodium falciparum
Authors: Karyana Muhammad , Burdarm Lenny , Yeung Shunmay , Kenangalem Enny , Wariker Noah , Maristela Rilia , Umana Ketut Gde , Vemuri Ram , Okoseray Maurits J , Penttinen Pasi M , Ebsworth Peter , Sugiarto Paulus , Anstey Nicholas M , Tjitra Emiliana , Price Richard N
Published: August 2008

Background

Multidrug resistance has emerged to both Plasmodium vivax and Plasmodium falciparum and yet the comparative epidemiology of these infections is poorly defined.

Methods

All laboratory-confirmed episodes of malaria in Timika, Papua, Indonesia, presenting to community primary care clinics and an inpatient facility were reviewed over a two-year period. In addition information was gathered from a house-to-house survey to quantify the prevalence of malaria and treatment-seeking behaviour of people with fever.

Results

Between January 2004 and December 2005, 99,158 laboratory-confirmed episodes of malaria were reported, of which 58% (57,938) were attributable to P. falciparum and 37% (36,471) to P. vivax. Malaria was most likely to be attributable to pure P. vivax in children under one year of age (55% 2,684/4,889). In the household survey, the prevalence of asexual parasitaemia was 7.5% (290/3,890) for P. falciparum and 6.4% (248/3,890) for P. vivax. The prevalence of P. falciparum infection peaked in young adults aged 15–25 years (9.8% 69/707), compared to P. vivax infection which peaked in children aged 1 to 4 years (9.5% 61/642). Overall 35% (1,813/5,255) of people questioned reported a febrile episode in the preceding month. Of the 60% of people who were estimated to have had malaria, only 39% would have been detected by the surveillance network. The overall incidence of malaria was therefore estimated as 876 per 1,000 per year (Range: 711–906).

Conclusion

In this region of multidrug-resistant P. vivax and P. falciparum, both species are associated with substantial morbidity, but with significant differences in the age-related risk of infection.
The relationship between the haemoglobin concentration and the haematocrit in Plasmodium falciparum malaria
Authors: Lee Sue J , Stepniewska Kasia , Anstey Nicholas , Ashley Elizabeth , Barnes Karen , Binh Tran Quang , D'Alessandro Umberto , Day Nicholas PJ , de Vries Peter J , Dorsey Grant , Guthmann Jean-Paul , Mayxay Mayfong , Newton Paul , Nosten Francois , Olliaro Piero , Osario Lyda , Pinoges Loretxu , Price Ric , Rowland Mark , Smithuis Frank , Taylor Robert , White Nicholas J
Published: August 2008

Background

Malaria is a very important cause of anaemia in tropical countries. Anaemia is assessed either by measurement of the haematocrit or the haemoglobin concentration. For comparisons across studies, it is often necessary to derive one measure from the other.

Methods

Data on patients with slide-confirmed uncomplicated falciparum malaria were pooled from 85 antimalarial drug trials conducted in 25 different countries, to assess the haemoglobin/haematocrit relationship at different time points in malaria. Using a linear random effects model, a conversion equation for haematocrit was derived based on 3,254 measurements from various time points (ranging from day 0 to day 63) from 1,810 patients with simultaneous measurements of both parameters. Haemoglobin was also estimated from haematocrit with the commonly used threefold conversion.

Results

A good fit was obtained using Haematocrit = 5.62 + 2.60 * Haemoglobin. On average, haematocrit/3 levels were slightly higher than haemoglobin measurements with a mean difference (± SD) of -0.69 (± 1.3) for children under the age of 5 (n = 1,440 measurements from 449 patients).

Conclusion

Based on this large data set, an accurate and robust conversion factor both in acute malaria and in convalescence was obtained. The commonly used threefold conversion is also valid.
Targeting focal adhesions:Helicobacter pylori-host communication in cell migration
Authors: Schneider Sabine , Weydig Christiane , Wessler Silja
Published: August 2008

Highly dynamic integrin-based focal adhesions provide an important structural basis for anchoring the cellular actin cytoskeleton to the surrounding extracellular matrix. The human pathogen Helicobacter pylori (H. pylori) directly targets integrins with drastic consequences on the epithelial cell morphology and migration, which might contribute to the disruption of the gastric epithelium in vivo. In this review, we summarize the recent findings concerning the complex mechanism through which H. pylori interferes with host integrin signaling thereby deregulating focal adhesions and the actin cytoskeleton of motile epithelial cells.