Geochemical Transactions最新文献

{"title":"Trace element partitioning between pyrochlore, microlite, fersmite and silicate melts","authors":"Stephan Klemme,&nbsp;Jasper Berndt","doi":"10.1186/s12932-020-00072-w","DOIUrl":"https://doi.org/10.1186/s12932-020-00072-w","url":null,"abstract":"<p>We present experimentally determined trace element partition coefficients (D) between pyrochlore-group minerals (Ca₂(Nb,Ta)₂O₆(O,F)), Ca fersmite (CaNb₂O₆), and silicate melts. Our data indicate that pyrochlores and fersmite are able to strongly fractionate trace elements during the evolution of SiO₂-undersaturated magmas. Pyrochlore efficiently fractionates Zr and Hf from Nb and Ta, with D_Zr and D_Hf below or equal to unity, and D_Nb and D_Ta significantly above unity. We find that D_Ta pyrochlore-group mineral/silicate melt is always higher than D_Nb, which agrees with the HFSE partitioning of?all other Ti–rich minerals such as perovskite, rutile, ilmenite or Fe-Ti spinel. Our experimental partition coefficients also show that, under oxidizing conditions, D_Th is higher than corresponding D_U and this implies that pyrochlore-group minerals may fractionate U and Th in silicate magmas. The rare earth element (REE) partition coefficients are around unity, only the light REE are compatible in pyrochlore-group minerals, which explains the high?rare earth element concentrations in naturally occurring magmatic pyrochlores.</p>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"21 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2020-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-020-00072-w","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4923129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Immobilization of Cr(VI) by sulphate green rust and sulphidized nanoscale zerovalent iron in sand media: batch and column studies","authors":"Flavia Digiacomo,&nbsp;Dominique J. Tobler,&nbsp;Thomas Held,&nbsp;Thomas Neumann","doi":"10.1186/s12932-020-00073-9","DOIUrl":"https://doi.org/10.1186/s12932-020-00073-9","url":null,"abstract":"<p>Chromate, Cr(VI), contamination in soil and groundwater poses serious threat to living organisms and environmental health worldwide. Sulphate green rust (GR_SO4), a naturally occurring mixed-valent iron layered double hydroxide has shown to be highly effective in the reduction of Cr(VI) to poorly soluble Cr(III), giving promise for its use as reactant for in situ remedial applications. However, little is known about its immobilization efficiency inside porous geological media, such as soils and sediments, where this reactant would ultimately be applied. In this study, we tested the removal of Cr(VI) by GR_SO4 in quartz sand fixed-bed column systems (diameter?×?length?=?1.4?cm?×?11?cm), under anoxic conditions. Cr(VI) removal efficiency (relative to the available reducing equivalents in the added GR_SO4) was determined by evaluating breakthrough curves performed at different inlet Cr(VI) concentrations (0.125–1?mM) which are representative of Cr(VI) concentrations found at contaminated sites, different flow rates (0.25–3?ml/min) and solution pH (4.5, 7 and 9.5). Results showed that (i) increasing Cr(VI) inlet concentration substantially decreased Cr(VI) removal efficiency of GR_SO4, (ii) flow rates had a lower impact on removal efficiencies, although values tended to be lower at higher flow rates, and (iii) Cr(VI) removal was enhanced at acidic pH conditions compared to neutral and alkaline conditions. For comparison, Cr(VI) removal by sulphidized nanoscale zerovalent iron (S-nZVI) in identical column experiments was substantially lower, indicating that S-nZVI reactivity with Cr(VI) is much slower compared to GR_SO4. Overall, GR_SO4 performed reasonably well, even at the highest tested flow rate, showing its versatility and suitability for Cr(VI) remediation applications in high flow environments.</p>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"21 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2020-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-020-00073-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4563608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to: Constraining the carbonate system in soils via testing the internal consistency of pH, pCO2 and alkalinity measurements","authors":"Sima Bargrizan,&nbsp;Ronald J. Smernik,&nbsp;Luke M. Mosley","doi":"10.1186/s12932-020-00071-x","DOIUrl":"https://doi.org/10.1186/s12932-020-00071-x","url":null,"abstract":"","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"21 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2020-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-020-00071-x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4844648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Frontiers and advances in environmental soil chemistry: a special issue in honor of Prof. Donald L. Sparks","authors":"Young-Shin Jun,&nbsp;Mengqiang Zhu,&nbsp;Derek Peak","doi":"10.1186/s12932-020-00070-y","DOIUrl":"https://doi.org/10.1186/s12932-020-00070-y","url":null,"abstract":"","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"21 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2020-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-020-00070-y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4669083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A golden period for environmental soil chemistry","authors":"Donald L. Sparks","doi":"10.1186/s12932-020-00068-6","DOIUrl":"https://doi.org/10.1186/s12932-020-00068-6","url":null,"abstract":"","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"21 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2020-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-020-00068-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4000653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraining the carbonate system in soils via testing the internal consistency of pH, pCO2 and alkalinity measurements","authors":"Sima Bargrizan,&nbsp;Ronald J. Smernik,&nbsp;Luke M. Mosley","doi":"10.1186/s12932-020-00069-5","DOIUrl":"https://doi.org/10.1186/s12932-020-00069-5","url":null,"abstract":"<p>Inorganic carbon exists in various dissolved, gaseous and solid phase forms in natural waters and soils. It is important to accurately measure and model these forms to understand system responses to global climate change. The carbonate system can, in theory, be fully constrained and modelled by measuring at least two out of the following four parameters: partial pressure (pCO₂), total alkalinity (TA), pH and dissolved inorganic carbon (DIC) but this has not been demonstrated in soils. In this study, this “internal consistency” of the soil carbonate system was examined by predicting pH of soil extracts from laboratory measurement of TA through alkalinity titration for solutions in which pCO₂ was fixed through equilibrating the soil solution with air with a known pCO₂. This predicted pH (pH_CO2) was compared with pH measured on the same soil extracts using spectrophotometric and glass electrode methods (pH_{spec and} pH_elec). Discrepancy between measured and calculated pH was within 0.00–0.1 pH unit for most samples. However, more deviation was observed for those sample with low alkalinity (≤?0.5?meq L^?1). This is likely attributable to an effect of dissolved organic matter, which can contribute alkalinity not considered in the thermodynamic carbonate model calculations; further research is required to resolve this problem. The effects of increasing soil pCO₂ was modelled to illustrate how internally consistent models can be used to predict risks of pH declines and carbonate mineral dissolution in some soils.</p>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"21 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2020-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-020-00069-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5162614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improvement of quantitative solution 31P NMR analysis of soil organic P: a study of spin–lattice relaxation responding to paramagnetic ions","authors":"Yunbin Jiang,&nbsp;Fengmin Zhang,&nbsp;Chao Ren,&nbsp;Wei Li","doi":"10.1186/s12932-020-00067-7","DOIUrl":"https://doi.org/10.1186/s12932-020-00067-7","url":null,"abstract":"<p>Solution ³¹P nuclear magnetic resonance (NMR) spectroscopy has been widely applied to analyze the speciation of soil organic P; however, this time-consuming technique suffers from a low analytical efficiency, because of the lack of fundamental information such as the spin–lattice relaxation (<i>T</i>₁) of ³¹P nucleus for model P compounds. In this study, we for the first time determined the <i>T</i>₁ values of twelve typical soil organic P compounds using the inversion recovery method. Furthermore, we examined the effect of co-existing paramagnetic ions (e.g., Fe³⁺ and Mn²⁺) on the reduction of the <i>T</i>₁ values of these compounds. Without the addition of paramagnetic ions, the <i>T</i>₁ values of twelve model P compounds ranged from 0.61?s for phytic acid to 9.65?s for orthophosphate. In contrast, the presence of paramagnetic ion significantly shortened the <i>T</i>₁ values of orthophosphate, pyrophosphate, and phytic acid to 1.29, 1.26, and 0.07?s, respectively, except that of deoxyribonucleic acid (DNA) remaining unchanged. Additionally, we evaluated the feasibility of improving the efficiency of quantitative ³¹P NMR analysis via addition of paramagnetic ion. Results show that, after an addition of 50?mg L^?1 paramagnetic ions, ³¹P NMR measurement can be 3 times more efficient, attributed to the reduced <i>T</i>₁ and the corresponding recycle delay.</p>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"21 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2020-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-020-00067-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4678134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of metal cation substitution on hexavalent chromium reduction by green rust","authors":"Andrew N. Thomas,&nbsp;Elisabeth Eiche,&nbsp;Jörg Göttlicher,&nbsp;Ralph Steininger,&nbsp;Liane G. Benning,&nbsp;Helen M. Freeman,&nbsp;Dominique J. Tobler,&nbsp;Marco Mangayayam,&nbsp;Knud Dideriksen,&nbsp;Thomas Neumann","doi":"10.1186/s12932-020-00066-8","DOIUrl":"https://doi.org/10.1186/s12932-020-00066-8","url":null,"abstract":"<p>Chromium contamination is a serious environmental issue in areas affected by leather tanning and metal plating, and green rust sulfate has been tested extensively as a potential material for in situ chemical reduction of hexavalent chromium in groundwater. Reported products and mechanisms for the reaction have varied, most likely because of green rust’s layered structure, as reduction at outer and interlayer surfaces might produce different reaction products with variable stabilities. Based on studies of Cr(III) oxidation by biogenic Mn (IV) oxides, Cr mobility in oxic soils is controlled by the solubility of the Cr(III)-bearing phase. Therefore, careful engineering of green rust properties, i.e., crystal/particle size, morphology, structure, and electron availability, is essential for its optimization as a remediation reagent. In the present study, pure green rust sulfate and green rust sulfate with Al, Mg and Zn substitutions were synthesized and reacted with identical chromate (CrO₄^2?) solutions. The reaction products were characterized by X-ray diffraction, pair distribution function analysis, X-ray absorption spectroscopy and transmission electron microscopy and treated with synthetic δ-MnO₂ to assess how easily Cr(III) in the products could be oxidized. It was found that Mg substitution had the most beneficial effect on Cr lability in the product. Less than 2.5% of the Cr(III) present in the reacted Mg-GR was reoxidized by δ-MnO₂ within 14?days, and the particle structure and Cr speciation observed during X-ray scattering and absorption analyses of this product suggested that Cr(VI) was reduced in its interlayer. Reduction in the interlayer lead to the linkage of newly-formed Cr(III) to hydroxyl groups in the adjacent octahedral layers, which resulted in increased structural coherency between these layers, distinctive rim domains, sequestration of Cr(III) in insoluble Fe oxide bonding environments resistant to reoxidation and partial transformation to Cr(III)-substituted feroxyhyte. Based on the results of this study of hexavalent chromium reduction by green rust sulfate and other studies, further improvements can also be made to this remediation technique by reacting chromate with a large excess of green rust sulfate, which provides excess Fe(II) that can catalyze transformation to more crystalline iron oxides, and synthesis of the reactant under alkaline conditions, which has been shown to favor chromium reduction in the interlayer of Fe(II)-bearing phyllosilicates.</p>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"21 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2020-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-020-00066-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4570760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discrimination of topsoil environments in a karst landscape: an outcome of a geochemical mapping campaign","authors":"Ozren Hasan,&nbsp;Slobodan Miko,&nbsp;Nikolina Ilijanić,&nbsp;Dea Brunović,&nbsp;Željko Dedić,&nbsp;Martina Šparica Miko,&nbsp;Zoran Peh","doi":"10.1186/s12932-019-0065-z","DOIUrl":"https://doi.org/10.1186/s12932-019-0065-z","url":null,"abstract":"<p>The study presented in this work emerged as a result of a multiyear regional geochemical survey based on low-density topsoil sampling and the ensuing geochemical atlas of Croatia. This study focuses on the Dinaric part of Croatia to expound the underlying mechanisms controlling the mobilities and variations in distribution of potentially harmful elements as observed from different environmental angles. Although serious environmental degradation of the vulnerable karst soil landscapes was expected to occur chiefly through the accumulation of various heavy metals, the most acute threat materialized through the soil acidification (Al-toxicity) affecting the entire Dinaric karst area. This picture surfaced from the analysis of all three investigated discriminant function models employing the abovementioned environmental criteria selected autonomously with respect to the evaluated soil geochemistry, namely, geologic setting, regional placement and land use. These models are presented by not only the characteristic discriminant-function diagrams but also a set of appropriate mathematically derived geochemical maps disclosing the allocations of potential threats to the karst soil landscapes posed by soil acidity.</p>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"21 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2020-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-019-0065-z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4161058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intermobility of barium, strontium, and lead in chloride and sulfate leach solutions","authors":"Mark Rollog,&nbsp;Nigel J. Cook,&nbsp;Paul Guagliardo,&nbsp;Kathy Ehrig,&nbsp;Sarah E. Gilbert,&nbsp;Matt Kilburn","doi":"10.1186/s12932-019-0064-0","DOIUrl":"https://doi.org/10.1186/s12932-019-0064-0","url":null,"abstract":"<p>Production of radionuclide-free copper concentrates is dependent on understanding and controlling the deportment of daughter radionuclides (RNs) produced from ²³⁸U decay, specifically ²²⁶Ra, ²¹⁰Pb, and ²¹⁰Po. Sulfuric acid leaching is currently employed in the Olympic Dam processing plant (South Australia) to remove U and fluorine from copper concentrates prior to smelting but does not adequately remove the aforementioned RN. Due to chemical similarities between lead and alkaline earth metals (including Ra), two sets of experiments were designed to understand solution interactions between Sr, Ba, and Pb at various conditions. Nanoscale secondary ion mass spectrometry (NanoSIMS) isotopic spatial distribution maps and laser ablation inductively coupled-plasma mass spectrometry transects were performed on laboratory-grown crystals of baryte, celestite, and anglesite which had been exposed to different solutions under different pH and reaction time conditions. Analysis of experimental products reveals three uptake mechanisms: overgrowth of nearly pure SrSO₄ and PbSO₄ on baryte; incorporation of minor of Pb and Ba into celestite due to diffusion; and extensive replacement of Pb by Sr (and less extensive replacement of Pb by Ba) in anglesite via coupled dissolution-reprecipitation reactions. The presence of H₂SO₄ either enhanced or inhibited these reactions. Kinetic modelling supports the experimental results, showing potential for extrapolating the (Sr, Ba, Pb)SO₄ system to encompass RaSO₄. Direct observation of grain-scale element distributions by nanoSIMS aids understanding of the controlling conditions and mechanisms of replacement that may be critical steps for Pb and Ra removal from concentrates by allowing construction of a cationic replacement scenario targeting Pb or Ra, or ideally all insoluble sulfates. Experimental results provide a foundation for further investigation of RN uptake during minerals processing, especially during acid leaching. The new evidence enhances understanding of micro- to nanoscale chemical interactions and not only aids determination of where radionuclides reside during each processing stage but also guides development of flowsheets targeting their removal.</p>","PeriodicalId":12694,"journal":{"name":"Geochemical Transactions","volume":"20 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2019-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12932-019-0064-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4230495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}