Wiley-Blackwell, p. appendix 10 p. This book provides a comprehensive introduction to the field of geochemistry. The book first lays out the. PDF | On Sep 2, , Yaoling Niu and others published White W. M. Geochemistry. pp. Wiley-Blackwell. Price £, € (HB);. Geochemistry (eBook, PDF) - White, William M. . Sons; Seitenzahl: ; Erscheinungstermin: ; Englisch; ISBN ; Artikelnr.
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GEOCHEMICAL PERSPECTIVES | WILLIAM M. WHITE. I. CONTENTS .. documented in other Geochemical Perspectives (e.g., Broecker, ; Arndt, ). geochemistry is somehow a marriage of the fields of geology and chemistry. Hence, the realm of geochemistry extends beyond the Earth to encompass the. Geochemistry / William M. White. Set in 11/12pt Sabon by Toppan Best-set Premedia Limited. 1 Chapter 8: Radiogenic isotope geochemistry.
Solutions and thermodynamics of multicomponent systems Applications of thermodynamics to the Earth Aquatic chemistry Trace elements in igneous processes Radiogenic isotope geochemistry Stable isotope geochemistry The big picture: Geochemistry of the solid earth Organic geochemistry, the carbon cycle, and climate Ebooks sind vom Umtausch ausgeschlossen.
We applied Sanger sequencing initially to reveal microbial diversity, and then used pyrosequencing to provide a higher-resolution analysis of community structure. To assess what impact, if any, the microbes had on aquifer carbonate geochemistry and potential modification through enhanced carbonate dissolution, we conducted in situ microcosm experiments in wells across the transition zone.
Previous in situ microcosm experiments from karst systems have been restricted to sulfidic cave and aquifer conditions see, e. The role of microbial colonization and activity on carbonate geochemistry and potential dissolution in freshwater karst systems has not been recognized. The results from our study demonstrate the importance of quantifying the extent to which microbes affect carbonate rock weathering in karst because microbially mediated dissolution may be more significant than previously considered.
The wells are completed within the Cretaceous Edwards Group carbonates and have the capacity to flow under artesian conditions. During the sampling time, water was pumped from the wells because of regional drought. Details are included in the Supplementary Materials and methods.
Aqueous geochemical analyses and computational modeling provided saturation conditions for aquifer minerals, specifically calcite and dolomite. A positive SI value indicates that precipitation with respect to a mineral is thermodynamically possible, whereas negative SI values indicate dissolution.
Microbiological samples and molecular analyses Depending on pump rate, This well served as a saline end-member Supplementary Figure S1a. Comal Springs was a freshwater end-member, and 27 l water was filtered from it.
All filters were aseptically cut into thirds and nucleic acids were extracted from each segment, following Fuhrman et al. Resulting pyrosequences were sorted based on RTL-provided barcodes to form different pyrosequence libraries corresponding to each sample.
In situ microcosm experiments and microscopy Mineral—microbe interactions are difficult to evaluate, especially in aquifers. Again, the origin of the isotopic fractionation between the different plant components and between the roots and the source of Ca is not well understood.
Zircon halogen geochemistry: Insights into Hadean-Archean fluids
It is known that large isotope fractionation during exchange reactions reflects isotopic differences between the equilibrium constants of Ca isotopologues.
This comes from the fact that the partitioning isotopes of a particular element among coexisting species depend on the vibrational frequency of the bond 19 , It is therefore possible that the Ca isotopic fractionations that occur among ligands relevant to Ca species in plants, animals, water or soils may be controlled by the difference of equilibrium constants between the isotopologues. Similar mechanisms have been proposed for the origin of Zn 22 , 23 , 24 , 25 , 26 , 27 Cu 28 , 29 , Ni 30 , Si 31 , 32 or Fe 33 , 34 , 35 , 36 isotope fractionations.
Here, we calculate the molecular orbitals of a large variety of Ca species to obtain the reduced partition function ratio RPFR of isotopologues. The ab initio calculations were then extended to hydrated Ca II complexes, chlorides, hydroxide, sulfate, carbonate, phosphates, citrates, malates, and oxalate.
The choice of oxalate was motivated by evidence of isotopic fractionation of Ca between urine and blood of human patients 14 and its importance as Ca carrier in plants Applications of our calculations to the understanding of Ca isotope variability into biological samples are briefly outlined.
Results and Discussion All the data are reported in Table 1 and Figs 1 and 2 for some of the most relevant molecules discussed. The geometry of each molecules are reported in Supplementary Information.
This agrees with the literature data obtained both experimentally 2. The treatment of the second coordination sphere was performed for hydrated complexes of a congener Mg The computational results of hydrated Ca ion are shown in Fig. The origin of this discrepancy is unclear at the moment.
Since the shift between 6- and 7-fold coordination is systematically in the same direction and magnitude, we adopt the small cluster model of six-fold coordination in vacuo for inter-molecule comparisons in the following sections.
Application to biological activity The application of Ca isotopes as biomarkers is based on the fact that Ca is enriched in the heavier isotopes in the order: bones, blood and urine 11 , 14 , 45 , It is therefore possible to monitor the Ca flux out and in the bones through Ca isotopic measurements, which is relevant to bone loss conditions associated with prolonged bed rests e.
However, the origin of this isotopic fractionation has been puzzling.The most straightforward explanation is that most of the light Ca is transferred from the free Ca specie of the blood to the osteoblasts and that reaction of apatite precipitation is quantitative and therefore not associated with further isotopic fractionation.
Energy, entropy and fundamental thermodynamic concepts On the student website pages, all the figures are available in PowerPoint format and include colour versions of the black and white images found in the text. On the other hand, osteoclasts are the cells responsible of the bone resorption that return Ca to the blood stream 47 , Geochimica et Cosmochimica Acta 75, He received a B.
Calculations are presented for additional Ca species that may be useful to interpret future Ca isotopic measurements.