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  • 1
    Language: English
    In: Biodiversity and Conservation, 2009, Vol.18(3), pp.503-505
    Keywords: Life Sciences ; Plant Sciences ; Tree Biology ; Evolutionary Biology ; Biology ; Ecology;
    ISSN: 0960-3115
    E-ISSN: 1572-9710
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  • 2
    Language: English
    In: Water, Air, & Soil Pollution, 2014, Vol.225(6), pp.1-5
    Keywords: Inter-disciplinary ; Multi-disciplinary ; Pluri-disciplinary ; Cross-disciplinary ; Trans-disciplinary
    ISSN: 0049-6979
    E-ISSN: 1573-2932
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  • 3
    Language: English
    In: Water, Air, & Soil Pollution, 2010, Vol.209(1), pp.377-390
    Description: Near-infrared diffuse reflectance sensing (NIRS) of soils has been the object of considerable interest and research in the last few years. This has been motivated by the prospect that this method seems to provide a cheap, convenient alternative to conventional, time-consuming methods for the measurement of a wide range of soil parameters. In particular, various authors have advocated that NIRS could be used to measure rapidly and non-destructively the concentration of trace metals in surface soils. Correlation analyses between NIRS spectra and trace metal concentration have yielded inconclusive results to date, suggesting that trace metal concentration may belong to a class of “tertiary” soil parameters, linked to NIRS spectra through “surrogate”, or indirect, correlations, involving some other primary or secondary parameter like clay or organic matter content, to which NIRS spectra are very sensitive. To assess the validity of this surrogate correlation hypothesis in the case of trace metals, experiments were carried out with soil samples varying only in the amount of trace metals they contain. Field-aged Hudson and Arkport soil pots spiked with Cu and Zn, freshly spiked samples of the same soils, and samples of a metalliferous peat soil from Western New York naturally rich in Cd and Zn were subjected to NIRS under laboratory conditions. Detailed analysis indicates that the NIR spectrum is sensitive to sample handling, including the orientation of the samples in the NIRS instrument, but that, at the same time, there is no discernable effect of the presence of trace metals on any part of the NIR spectrum. These results provide strong experimental support to the hypothesis of “surrogate” correlation for trace metals, and indicate that trace metals, even in severely contaminated soils, should not interfere with the NIR sensing of primary or secondary parameters, like organic matter content. Further work is needed to determine if this feature of NIR spectra extends to other soil chemical parameters.
    Keywords: Soil metal contamination ; Chemical analysis ; Near-infrared spectroscopy ; Remote sensing
    ISSN: 0049-6979
    E-ISSN: 1573-2932
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  • 4
    Language: English
    In: Journal of Soils and Sediments, 2015, Vol.15(3), pp.634-647
    Description: Byline: Burcu UyuAur (1), Chunyan Li (2), Philippe C. Baveye (3), Christophe J. G. Darnault (2) Keywords: Geochemistry; Precipitation; Sorption; Two-site and mobile-immobile transport models; Uranyl silicates; Vadose zone Abstract: Purpose Uranium contamination of subsurface environments was once thought to be an isolated occurrence, mostly at production sites. But recent evidence has shown that the presence of uranium in phosphate fertilizers has caused massive amounts of this element to be released worldwide. Concerns are related to uranium movement to groundwater supplies and its significant toxicological risks to human populations. Information is direly needed on how geochemical processes control uranium transport in the vadose zone. Materials and methods Laboratory experiments were performed to investigate the effects of the pH of the soil solution on the reactive transport of uranium(VI) in the vadose zone. The uranium solution was prepared by dilution of a 10.sup.-3 M stock solution of uranium perchlorate, (UO.sub.2(ClO.sub.4).sub.2), with DI water. Two U(VI) solutions were prepared at concentrations of 2x10.sup.-6 M at pH 6 and 11 and were percolated under steady-state conditions through columns filled with sand. The convective-dispersion equation (CDE) was used to analyze the tracer and uranium breakthrough curves resulting from the column experiments. The program CXTFIT was used to estimate the transport parameters of equilibrium and nonequilibrium (i.e., two-site and mobile-immobile) models applied to the experimental data. Results and discussion Comparison of U(VI) breakthrough behavior at pH 6 with that of a nonreactive tracer indicated that U(VI) transport was significantly retarded, and about 52 % of the added U(VI) adsorbed to the quartz sand, likely in the cationic forms U[O.sub.2]OH.sup.+ and UO .sub.2 .sup.2+ . The adsorption was reversible upon the addition of deionized water. At pH 11, the U(VI) breakthrough curve increased gradually and reached a plateau value C/C .sub.0 oscillating between 72 and 82 %. Upon reaction, Si was released from the dissolution of quartz sand, which allowed the possible transport of U(VI) following precipitation of a U(VI) containing solid, such as uranyl-silicate minerals, or sorption of U(VI) onto silica colloids. Two-site and mobile-immobile (MIM) models suggested an influence of either rate-limited mass transfer processes or immobile/mobile water partitioning in U(VI) reactive transport. Conclusions The reactive transport of U(VI) governed by adsorption-desorption processes, precipitation, and complexation reactions in which kinetic behaviors are controlled by pH, solution chemistry, and heterogeneous flow regime impacts the mobility of U(VI). The column transport experiments indicated that under geochemical conditions and vadoze zone processes (preferential flow) that favor the mobility of U(VI), dissolved- and colloidal-phase associations of U(VI) may be transported rapidly and in high concentrations from the soil surface to the groundwater. Author Affiliation: (1) Tubitak Marmara Research Center, P.K. 21 41470, Gebze, Kocaeli, Turkey (2) Department of Environmental Engineering and Earth Sciences, L.G. Rich Environmental Laboratory, Clemson University, 342 Computer Court, Anderson, SC, 29625, USA (3) Laboratory of Soil and Water Engineering, Department of Civil and Environmental Engineering, Rensselaer Polytechnic University, 319 Materials Research Center, 110 Eighth St., Troy, NY, 12180, USA Article History: Registration Date: 31/10/2014 Received Date: 19/05/2014 Accepted Date: 31/10/2014 Online Date: 20/11/2014 Article note: Responsible Editor: Dong-Mei Zhou
    Keywords: Geochemistry ; Precipitation ; Sorption ; Two-site and mobile-immobile transport models ; Uranyl silicates ; Vadose zone
    ISSN: 1439-0108
    E-ISSN: 1614-7480
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