2024-03-29T08:50:17Zhttps://scholarworks.iu.edu/dspace-oai/requestoai:scholarworks.iu.edu:2022/139712021-10-18T12:33:08Zcom_2022_443com_2022_19675com_2022_19673col_2022_13935
Stable silicon isotopes of groundwater, feldspars, and clay coatings in the Navajo Sandstone aquifer, Black Mesa, Arizona, USA
Halliday, A. N.
Reynolds, B. C.
Zhu, Chen
Georg, R. B.
groundwater samples were from the Navajo Sandstone aquifer at Black Mesa, Arizona, USA, and the Si isotope composition
of detrital feldspars and secondary clay coatings in the aquifer were also analyzed. Silicon isotope compositions were measured
using high-resolution multi-collector inductively coupled mass spectrometry (HR-MC-ICP-MS) (Nu1700 & NuPlasma
HR). The quartz dominated bulk rock and feldspar separates have similar d30Si of 0.09 ± 0.04&and 0.15 ± 0.04&(±95%
SEM), respectively, and clay separates are isotopically lighter by up to 0.4& compared to the feldspars. From isotopic massbalance
considerations, co-existing aqueous fluids should have d30Si values heavier than the primary silicates. Positive d30Si
values were only found in the shallow aquifer, where Si isotopes are most likely fractionated during the dissolution of feldspars
and subsequent formation of clay minerals. However, d30Si decreases along the flow path from 0.56& to 1.42&, representing
the most negative dissolved Si isotope composition so far found for natural waters. We speculate that the
enrichment in 28Si is due to dissolution of partly secondary clay minerals and low-temperature silcretes in the Navajo Sandstone.
The discovery of the large range and systematic shifts of d30Si values along a groundwater flow path illustrates the
potential utility of stable Si isotopes for deciphering the Si cycling in sedimentary basins, tracing fluid flow, and evaluating
global Si cycle.
2011-12-13
2011-12-13
2009-02-14
Article
Georg, R. B., Zhu, C. Reynolds, R.C., and Halliday, A.N. (2009) Stable silicon isotopes of groundwater, feldspars, and clay coatings in the Navajo Sandstone aquifer, Black Mesa, Arizona, USA. Geochimica et Cosmochimica Acta, v.73, 229-2241.
http://hdl.handle.net/2022/13971
en_US
http://www.sciencedirect.com/science/article/pii/S0016703709000726
Copyright 2009 Elsevier Ltd. All rights reserved.
Elsevier
oai:scholarworks.iu.edu:2022/139782021-10-19T01:07:36Zcom_2022_443com_2022_19675com_2022_19673col_2022_13935
Alkali feldspar dissolution and secondary mineral precipitation in batch systems: 3. Saturation states of product minerals and reaction paths
Lu, Peng
Zhu, Chen
In order to evaluate the complex interplay between dissolution and precipitation reaction kinetics, we examined the
hypothesis of partial equilibria between secondary mineral products and aqueous solutions in feldspar–water systems. Speciation
and solubility geochemical modeling was used to compute the saturation indices (SI) for product minerals in batch feldspar
dissolution experiments at elevated temperatures and pressures and to trace the reaction paths on activity–activity
diagrams. The modeling results demonstrated: (1) the experimental aqueous solutions were supersaturated with respect to
product minerals for almost the entire duration of the experiments; (2) the aqueous solution chemistry did not evolve along
the phase boundaries but crossed the phase boundaries at oblique angles; and (3) the earlier precipitated product minerals did
not dissolve but continued to precipitate even after the solution chemistry had evolved into the stability fields of minerals lower
in the paragenesis sequence. These three lines of evidence signify that product mineral precipitation is a slow kinetic process
and partial equilibria between aqueous solution and product minerals were not held. In contrast, the experimental evidences
are consistent with the hypothesis of strong coupling of mineral dissolution/precipitation kinetics [e.g., Zhu C., Blum A. E.
and Veblen D. R. (2004a) Feldspar dissolution rates and clay precipitation in the Navajo aquifer at Black Mesa, Arizona,
USA. In Water–Rock Interaction (eds. R. B. Wanty and R. R. I. Seal). A.A. Balkema, Saratoga Springs, New York. pp.
895–899]. In all batch experiments examined, the time of congruent feldspar dissolution was short and supersaturation with
respect to the product minerals was reached within a short period of time. The experimental system progressed from a dissolution
driven regime to a precipitation limited regime in a short order. The results of this study suggest a complex feedback
between dissolution and precipitation reaction kinetics, which needs to be considered in the interpretation of field based dissolution
rates.
2011-12-18
2011-12-18
2009-03-26
Article
Zhu, C., and Lu, P., Alkali Feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems: 3. Saturation States of Product Minerals and Reaction Paths. Geochimica et Cosmochimica Acta 73 (2009) 3171–3200. doi: 10.1016/j.gca.2009.03.015.
http://hdl.handle.net/2022/13978
en_US
http://www.sciencedirect.com.ezproxy.lib.indiana.edu/science/article/pii/S0016703709001586
Copyright 2009 Elsevier Ltd. All rights reserved.
Elsevier
oai:scholarworks.iu.edu:2022/139792021-10-19T01:07:40Zcom_2022_443com_2022_19675com_2022_19673col_2022_13935
Coupled alkali feldspar dissolution and secondary mineral precipitation in batch systems: 4. Numerical modeling of kinetic reaction paths
Ganor, Jiwchar
Zheng, Zuoping
Lu, Peng
Zhu, Chen
This paper explores how dissolution and precipitation reactions are coupled in batch reactor experimental systems at elevated
temperatures. This is the fourth paper in our series of “Coupled Alkali Feldspar Dissolution and Secondary Mineral
Precipitation in Batch Systems”. In our third paper, we demonstrated via speciation–solubility modeling that partial equilibrium
between secondary minerals and aqueous solutions was not attained in feldspar hydrolysis batch reactors at 90–300 C
and that a strong coupling between dissolution and precipitation reactions follows as a consequence of the slower precipitation
of secondary minerals (Zhu and Lu, 2009). Here, we develop this concept further by using numerical reaction path models
to elucidate how the dissolution and precipitation reactions are coupled. Modeling results show that a quasi-steady state
was reached. At the quasi-steady state, dissolution reactions proceeded at rates that are orders of magnitude slower than the
rates measured at far from equilibrium. The quasi-steady state is determined by the relative rate constants, and strongly influenced
by the function of Gibbs free energy of reaction (DGr) in the rate laws.
To explore the potential effects of fluid flow rates on the coupling of reactions, we extrapolate a batch system (Ganor et al.,
2007) to open systems and simulated one-dimensional reactive mass transport for oligoclase dissolution and kaolinite precipitation
in homogeneous porous media. Different steady states were achieved at different locations along the one-dimensional
domain. The time-space distribution and saturation indices (SI) at the steady states were a function of flow rates for a given
kinetic model. Regardless of the differences in SI, the ratio between oligoclase dissolution rates and kaolinite precipitation
rates remained 1.626, as in the batch system case (Ganor et al., 2007). Therefore, our simulation results demonstrated coupling
among dissolution, precipitation, and flow rates.
Results reported in this communication lend support to our hypothesis that slow secondary mineral precipitation explains
part of the well-known apparent discrepancy between lab measured and field estimated feldspar dissolution rates (Zhu et al.,
2004). Here we show how the slow secondary mineral precipitation provides a regulator to explain why the systems are held
close to equilibrium and show how the most often-quoted “near equilibrium” explanation for an apparent field-lab discrepancy
can work quantitatively. The substantiated hypothesis now offers the promise of reconciling part of the apparent fieldlab
discrepancy.
2011-12-18
2011-12-18
2010-04-27
Article
Zhu, C., Lu, P., Zheng, Z., Ganor, J., Alkali Feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems: 4. Numerical modeling of reaction path. Geochimica et Cosmochimica Acta 74 (2010) 3963–3983. DOI: 10.1016/j.gca.2010.04.012.
http://hdl.handle.net/2022/13979
en_US
http://www.sciencedirect.com.ezproxy.lib.indiana.edu/science/article/pii/S0016703710001882
Copyright 2010 Elsevier Ltd. All rights reserved.
Elsevier
oai:scholarworks.iu.edu:2022/143742021-10-19T01:50:28Zcom_2022_443com_2022_19675com_2022_19673col_2022_13935
Lead coprecipitation with iron oxyhydroxide nano-particles
Zhu, Chen
Elswick, Erika
Konishi, Hiromi
Li, Qin
Kelly, Shelly
Nuhfer, Noel T.
Lu, Peng
Pb2+ and Fe3+ coprecipitation was studied with sorption edge measurements, desorption experiments, sorbent aging, High Resolution Transmission and Analytical Electron Microscopy (HR TEM–AEM), and geochemical modeling. Companion adsorption experiments were also conducted for comparison. The macroscopic chemical and near atomic scale HRTEM data supplemented our molecule scale analysis with EXAFS (Kelly et al., 2008). Coprecipitation of Pb2+ with ferric oxyhydroxides occurred at pH 4 and is more efficient than adsorption in removing Pb2+ from aqueous solutions at similar sorbate/sorbent ratios and pH. X-ray Diffraction (XRD) shows peaks of lepidocrocite and two additional broad peaks similar to fine particles of 2-line ferrihydrite (2LFh). HRTEM of the Pb–Fe coprecipitates shows a mixture of 2–6 nm diameter spheres and 8–20 by 200–300 nm needles, both uniformly distributed with Pb2+. Geochemical modeling shows that surface complexation models fit the experimental data of low Pb:Fe ratios when a high site density is used. Desorption experiments show that more Pb2+ was released from loaded sorbents collected from adsorption experiments than from Pb to Fe coprecipitates at dilute EDTA concentrations. Desorbed Pb2+ versus dissolved Fe3+ data show a linear relationship for coprecipitation (CPT) desorption experiments but a parabolic relationship for adsorption (ADS) experiments.
Based on these results, we hypothesize that Pb2+ was first adsorbed onto the nanometer-sized, metastable, iron oxyhydrox- ide polymers of 2LFh with domain size of 2–3 nm. As these nano-particles assembled into larger particles, some Pb2+ was trapped in the iron oxyhydroxide structure and re-arranged to form solid solutions. Therefore, the CPT contact method pro- duced more efficient removal of Pb2+ than the adsorption contact method, and Pb2+ bound in CPT solids represent a more stable sequestration of Pb2+ in the environment than Pb2+ adsorbed on iron oxyhydroxide surfaces.
2012-04-18
2012-04-18
2011-06-02
Article
Lu, P., NT Nuhfer, S. Kelly, Q. Li, H. Konishi, E. Elswick, C. Zhu. Lead coprecipitation with iron oxyhydroxide nano-particles. Geochimica et Cosmochimica Acta 75, 4547-4561, doi:10.1016/j.gca.2011.05.035.
http://hdl.handle.net/2022/14374
en_US
http://www.sciencedirect.com/science/journal/00167037/75/16
Copyright 2011 Elsevier Ltd. All rights reserved.
Elsevier
oai:scholarworks.iu.edu:2022/184852021-10-18T12:34:19Zcom_2022_443com_2022_19675com_2022_19673col_2022_13935
The microbial ferrous wheel in a neutral pH groundwater seep
Roden, E.E.
McBeth, J.M.
Blothe, M.
Percak-Dennett, E.M.
Fleming, E.J.
Holyoke, R.R.
Luther III, G.W.
Emerson, D.
Schieber, J.
Aeromonas
Aquabacterium
Bacteria (microorganisms)
Betaproteobacteria
Desulfovibrio
Gallionella
Geobacter
Rhodoferax
Evidence for microbial Fe redox cycling was documented in a circumneutral pH ground-water seep near Bloomington, Indiana. Geochemical and microbiological analyses were conducted at two sites, a semi-consolidated microbial mat and a floating puffball structure. In situ voltammetric microelectrode measurements revealed steep opposing gradients of o2 and Fe(I I) at both sites, similar to other groundwater seep and sedimentary environments known to support microbial Fe redox cycling. The puffball structure showed an abrupt increase in dissolved Fed I) just at its surface (~5cm depth), suggesting an internal Fe(I I) source coupled to active Fed 1I) reduction. Most probable number enumerations detected microaerophilic Fe(II)-oxidizing bacteria (FeoB) and dissimilatory Fe(III)-reducing bacteria (FeRB) at densities of 102 to 105 cells ml_~1 in samples from both sites. In vitro Fed 1I) reduction experiments revealed the potential for immediate reduction (no lag period) of native Fe(III) oxides. Conventional full-length 16S rRNA gene clone libraries were compared with high throughput barcode sequencing of theV1, V4, orV6 variable regions of 16S rRNA genes in order to evaluate the extent to which new sequencing approaches could provide enhanced insight into the composition of Fe redox cycling microbial community structure. The composition of the clone libraries suggested a lithotroph-dominated microbial community centered around taxa related to known FeoB (e.g., Gallionella, Sideroxydans, Aquabacterium). Sequences related to recognized FeRB (e.g., Rhodoferax, Aeromonas, Geobacter, Desulfovibrio) were also well-represented. overall, sequences related to known FeoB and FeRB accounted for 88 and 59% of total clone sequences in the mat and puffball libraries, respectively. Taxa identified in the barcode libraries showed partial overlap with the clone libraries, but were not always consistent across different variable regions and sequencing platforms. However, the barcode libraries provided confirmation of key clone library results (e.g., the predominance of Betaproteobacteria) and an expanded view of lithotrophic microbial community composition.
2014-07-08
2014-07-08
2012
Article
Roden, E. E., McBeth, J. M., Blothe, M., Percak-Dennett, E. M., Fleming, E. J., Holyoke, R. R., . . . Schieber, J. (2012). The microbial ferrous wheel in a neutral pH groundwater seep. Frontiers in Microbiology, 3, 172. http://dx.doi.org/10.3389/fmicb.2012.00172
http://hdl.handle.net/2022/18485
en_US
https://doi.org/10.3389/fmicb.2012.00172
http://creativecommons.org/licenses/by-nc/3.0/
© 2012 Roden, McBeth, Blöthe, Percak-Dennett, Fleming, Holyoke, Luther III, Emerson and Schieber. This is an open-access article distributed under the terms of the Creative Commons Attribution Non Commercial License, which permits non-commercial use, distribution, and reproduction in other forums, provided the original authors and source are credited.
Frontiers Media S.A
oai:scholarworks.iu.edu:2022/184922021-10-18T12:21:34Zcom_2022_443com_2022_19675com_2022_19673col_2022_13935
Mineralogy and chemistry of altered Icelandic basalts: Application to clay mineral detection and understanding aqueous environments on Mars
Ehlmann, B.L.
Bish, D.L.
Ruff, S.W.
Mustard, J.F.
analog model
basalt
clay mineral
geochemistry
Mars
mineral alteration
mineralogy
planetary surface
We used a suite of techniques, including those emulating compositional data sets obtained from Mars orbit and obtainable at the Mars surface, to examine aqueous alteration of basaltic rocks from Iceland as a mineralogic and geochemical analog for Noachian environments on Mars. A sample suite was collected for laboratory measurement of (1) whole-rock visible/near-infrared (VNIR) reflectance and thermal infrared (TIR) emission spectra; (2) VNIR and TIR reflectance spectra of particle-size separates derived from the bulk rock and from materials extracted from fractures/vesicles; (3) X-ray diffraction (XRD) patterns for determination of quantitative modal mineralogy; (4) major element chemistry using flux fusion of whole-rock powders; and (5) electron microprobe analyses of minerals in thin sections. Conclusions about aqueous alteration can be influenced by technique. For these basalts, whole-rock chemical data showed scant evidence for chemical fractionation, but TIR, VNIR, and XRD measurements identified distinctive assemblages of hydrous silicate minerals, differing by sample. XRD provided the most complete and accurate quantitative determination of sample mineralogy. However, VNIR spectroscopy was the technique most useful for determining composition of low-abundance smectite clays, and TIR spectroscopy was the most useful for recognizing hydrated silicates in thin surface coatings. High spatial resolution mineralogical and chemical data sets were useful for understanding the texture and distribution of alteration products and variations in fluid chemistry. No single approach provides a complete assessment of the environment of alteration, demonstrating the importance of employing multiple, synergistic mineralogical and geochemical techniques and instruments in exploration of rock strata from aqueous paleoenvironments on Mars.
2014-07-15
2014-07-15
2012
Article
Ehlmann, B. L., Bish, D. L., Ruff, S. W., & Mustard, J. F. (2012). Mineralogy and chemistry of altered Icelandic basalts: Application to clay mineral detection and understanding aqueous environments on Mars. Journal of Geophysical Research E: Planets, 117(10), E00J16. http://dx.doi.org/10.1029/2012JE004156
http://hdl.handle.net/2022/18492
en_US
https://doi.org/10.1029/2012JE004156
© 2012. American Geophysical Union. All Rights Reserved.
American Geophysical Union