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  • 2015  (11)
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  • 2015  (11)
  • 1
    Language: English
    In: Revista Brasileira de Ciência do Solo, 01 June 2015, Vol.39(3), pp.637-642
    Description: In recent years, many researchers have claimed that world reserves of rock phosphate were getting depleted at an alarming rate, putting us on the path to scarcity of that essential resource within the next few decades. Others have claimed that such alarmist forecasts were frequent in the past and have always been proven unfounded, making it likely that the same will be true in the future. Both viewpoints are directly relevant to the level of funding devoted to research on the use of phosphate fertilizers. In this short essay, it is argued that information about future reserves of P or any other resource are impossible to predict, and therefore that the threat of a possible depletion of P reserves should not be used as a key motivation for an intensification of research on soil P. However, there are other, more compelling reasons, both geopolitical and environmental, to urgently step up our collective efforts to devise agricultural practices that make better use of P than is the case at the moment.
    Keywords: Reservas de Fósforo ; Disponibilidade de Fósforo ; Depleção de Fósforo ; Segurança Alimentar
    ISSN: 1806-9657
    Source: Directory of Open Access Journals (DOAJ)
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  • 2
    Language: English
    In: Journal of Hazardous Materials, 21 March 2015, Vol.285, pp.137-139
    Description: In recent years, several authors have suggested repeatedly that visible and near-infrared reflectance spectroscopy (VNIRS) could be an advantageous alternative to traditional wet-laboratory methods for the measurement of heavy metal concentrations in soils. In this comment, we argue that, on the contrary, VNIRS is of limited practical use in such a context and should not serve as an excuse to get rid of direly needed laboratory facilities. The key reasons are that VNIRS spectra are irremediably insensitive to the presence of heavy metals, that the effect of soil moisture and surface rugosity on VNIR sensing still has to be satisfactorily accounted for, and finally that VNIRS probes an extremely thin layer of soil at the surface, which is generally irrelevant in terms of plant growth. Given these intrinsic limitations, it seems indicated to put the persistent VNIRS myth to rest, and to explore other measurement techniques that may have more potential.
    Keywords: Engineering ; Law
    ISSN: 0304-3894
    E-ISSN: 1873-3336
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  • 3
    Language: English
    In: Ecological Modelling, 24 February 2015, Vol.298, pp.24-38
    Description: Since the late 1970s, thousands of scholarly articles, books and reports have dealt with the application of the mathematical theory of geostatistics to characterize the spatial “variability” of soils, and to produce soil property maps. Insensibly, this application of geostatistics appears to have become an end in itself, and the reasons why one should be concerned about the spatial heterogeneity of soil properties are rarely if ever made clear any more. In this context, the purpose of the present critical review article is to return to some of the primal questions that motivated this interest in the topic several decades ago. After a brief review of the background behind the application of geostatistics to soils, a number of situations and modeling efforts are described where, even though soils undoubtedly vary spatially, nothing seems to be gained practically by explicitly accounting for their spatial heterogeneity in order to reach a number of management or research objectives. Contrastedly, whenever the spatial heterogeneity of soil properties in the field might be relevant, it is shown that very different perceptions about it emerge, depending on the type of measurement that is performed. This suggests that the approach one adopts to characterize spatially-varying soil properties should be dictated by whatever goal one pursues. For example, if the objective is to evaluate the “ecosystem services” of soils in a given region and to reach decisions about them, one should probably first consider the (typically large) spatial scale that is most relevant to the decision-making process, then proceed via a top-down approach to characterize the spatial heterogeneity of soil services, if and when appropriate. In other contexts, it is argued that measurements should be patterned after the behavior of plants or microbes present in soils, relative to which, unfortunately, the macroscopic measurements that are now routinely carried out appear largely irrelevant or misleading. The article concludes with a number of potential lessons learned from the analysis of the research on the spatial heterogeneity of soils, which bear relevance to the broader practice of soil science.
    Keywords: Soil Heterogeneity ; Mathematical Modeling ; Microheterogeneity ; Microenvironment ; Plant Roots ; Measuring Devices ; Environmental Sciences ; Ecology
    ISSN: 0304-3800
    E-ISSN: 1872-7026
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  • 4
    Language: English
    In: Journal of Hazardous Materials, March 21, Vol.285, p.137(3)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jhazmat.2014.11.043 Byline: Philippe C. Baveye, Magdeline Laba Abstract: In recent years, several authors have suggested repeatedly that visible and near-infrared reflectance spectroscopy (VNIRS) could be an advantageous alternative to traditional wet-laboratory methods for the measurement of heavy metal concentrations in soils. In this comment, we argue that, on the contrary, VNIRS is of limited practical use in such a context and should not serve as an excuse to get rid of direly needed laboratory facilities. The key reasons are that VNIRS spectra are irremediably insensitive to the presence of heavy metals, that the effect of soil moisture and surface rugosity on VNIR sensing still has to be satisfactorily accounted for, and finally that VNIRS probes an extremely thin layer of soil at the surface, which is generally irrelevant in terms of plant growth. Given these intrinsic limitations, it seems indicated to put the persistent VNIRS myth to rest, and to explore other measurement techniques that may have more potential. Author Affiliation: (a) Soil and Water Laboratory, Department of Civil and Environmental Engineering, Rensselaer Polytechnic Institute, 110 8th street, Troy, NY 12180, USA (b) Department of Natural Resources, Cornell University, Ithaca, NY 14850, USA Article History: Received 22 July 2014; Accepted 2 November 2014
    Keywords: Soil Pollution ; Soil Moisture ; Spectroscopy ; Heavy Metals
    ISSN: 0304-3894
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: Ecological Modelling, Feb 24, Vol.298, p.24(15)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ecolmodel.2014.03.018 Byline: Philippe C. Baveye, Magdeline Laba Abstract: * Reviews background of the application of geostatistics to soils. * Soil spatial heterogeneity does not always have to be accounted for explicitly. * Perception of heterogeneity depends closely on measurement carried out. * For cases related to plants and microbes, different measurements are needed. * Lessons from the geostatistical story are applicable to soil science in general. Author Affiliation: (a) Soil and Water Laboratory, Department of Civil and Environmental Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA (b) SIMBIOS Centre, Abertay University, Kydd Building, 40 Bell Street, Dundee DD1 1HG, Scotland, UK (c) Department of Natural Resources, Cornell University, Ithaca, NY 14850, USA
    Keywords: Soils ; Geostatistics
    ISSN: 0304-3800
    Source: Cengage Learning, Inc.
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  • 6
    Language: English
    In: PLoS ONE, 01 January 2015, Vol.10(9), p.e0137205
    Description: There is currently a significant need to improve our understanding of the factors that control a number of critical soil processes by integrating physical, chemical and biological measurements on soils at microscopic scales to help produce 3D maps of the related properties. Because of technological limitations, most chemical and biological measurements can be carried out only on exposed soil surfaces or 2-dimensional cuts through soil samples. Methods need to be developed to produce 3D maps of soil properties based on spatial sequences of 2D maps. In this general context, the objective of the research described here was to develop a method to generate 3D maps of soil chemical properties at the microscale by combining 2D SEM-EDX data with 3D X-ray computed tomography images. A statistical approach using the regression tree method and ordinary kriging applied to the residuals was developed and applied to predict the 3D spatial distribution of carbon, silicon, iron, and oxygen at the microscale. The spatial correlation between the X-ray grayscale intensities and the chemical maps made it possible to use a regression-tree model as an initial step to predict the 3D chemical composition. For chemical elements, e.g., iron, that are sparsely distributed in a soil sample, the regression-tree model provides a good prediction, explaining as much as 90% of the variability in some of the data. However, for chemical elements that are more homogenously distributed, such as carbon, silicon, or oxygen, the additional kriging of the regression tree residuals improved significantly the prediction with an increase in the R2 value from 0.221 to 0.324 for carbon, 0.312 to 0.423 for silicon, and 0.218 to 0.374 for oxygen, respectively. The present research develops for the first time an integrated experimental and theoretical framework, which combines geostatistical methods with imaging techniques to unveil the 3-D chemical structure of soil at very fine scales. The methodology presented in this study can be easily adapted and applied to other types of data such as bacterial or fungal population densities for the 3D characterization of microbial distribution.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 7
    Language: English
    In: Frontiers in Environmental Science, 01 February 2015, Vol.3
    Description: Current estimates of global soil C are slightly over 4000 Pg C, which is more than five and a half times the amount of carbon currently in the atmosphere or, put differently, is equivalent to about 400 times the amount of C released yearly to the atmosphere by fossil fuel consumption or cement manufacture...
    Keywords: Food Security ; Global Climate Change ; Microorganisms ; Soil Structure ; Soil Organic Matter ; Soil Science Research ; Environmental Sciences
    E-ISSN: 2296-665X
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  • 8
    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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  • 9
    Language: English
    In: 2015
    Keywords: Soil Water ; Near-Infrared Spectroscopy ; Soil Pollution ; Plant Growth ; Heavy Metals
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 10
    Language: English
    In: Ecotoxicology and Environmental Safety, Feb, 2015, Vol.112, p.122(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ecoenv.2014.10.022 Byline: Yizhang Liu, Tangfu Xiao, Philippe C. Baveye, Jianming Zhu, Zengping Ning, Huajun Li Abstract: In various parts of the world, high cadmium (Cd) concentrations in environment are not related to anthropogenic contamination but have natural origins. Less is known about health risks that arise under these conditions. This study aimed to discuss the pollution of Cd with natural sources, and to investigate the concentration of Cd in food crops and the urine of inhabitants in an area of southwestern China. The results showed that the arable soils are moderately contaminated by Cd (I.sub.geo=1.51) relative to the local background, with a high ecological risk (E.sub.r=218). The chemical fractions of Cd in soils with natural sources are probably controlled by parent materials and mostly in residual phase. The average Cd concentrations were 0.68mgkg.sup.-1 (fresh weight) in local vegetables, 0.04mgkg.sup.-1 in rice, and 0.14[mu]gL.sup.-1 in water. Leafy vegetable tends to accumulate more Cd than the other crops. The calculated Target Hazard Quotient (THQ) had a much higher value (4.33) for Cd, suggesting that Cd represents a significant potential risk to the local population. The urinary Cd concentrations (mean at 3.92[mu]gL.sup.-1 for male and 4.85[mu]gL.sup.-1 for female) of inhabitants in the study area were significantly higher (p〈0.05) than those from the control area (mean at 0.8[mu]gL.sup.-1 for male and 0.42[mu]gL.sup.-1 for female). Male and female test subjects had similar urinary Cd levels (p0.05), but age seemed to lead to an increase in Cd in the urine. These findings show that naturally-occurring Cd in local soils is taken up appreciably by local food crops, and that dietary exposure of Cd through vegetable ingestion is a major exposure pathway for local populations, and a potential risk to public health in the study area. Author Affiliation: (a) State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China (b) University of Chinese Academy of Sciences, Beijing 100049, China (c) Soil and Water Laboratory, Department of Civil and Environmental Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA (d) Health Bureau of Wushan County, Chongqing 404700, China Article History: Received 19 June 2014; Revised 15 October 2014; Accepted 19 October 2014
    Keywords: Local Food -- Health Aspects ; Public Health -- Health Aspects ; Cadmium -- Health Aspects
    ISSN: 0147-6513
    Source: Cengage Learning, Inc.
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