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PHYSICS (578 journals)

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Journal Cover Physics and Chemistry of the Earth, Parts A/B/C
  [SJR: 0.611]   [H-I: 26]   [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1474-7065
   Published by Elsevier Homepage  [3031 journals]
  • Advance in seismic site response: Usual practices and innovative methods
    • Authors: Francesco Panzera; Sebastiano D'Amico; Jan Burjanek; Marta Pischiutta
      Pages: 1 - 2
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): Francesco Panzera, Sebastiano D'Amico, Jan Burjanek, Marta Pischiutta


      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2017.04.005
      Issue No: Vol. 98 (2017)
       
  • From standard to fractional structural visco-elastodynamics: Application
           to seismic site response
    • Authors: C. Germoso; A. Fraile; E. Alarcon; J.V. Aguado; F. Chinesta
      Pages: 3 - 15
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): C. Germoso, A. Fraile, E. Alarcon, J.V. Aguado, F. Chinesta
      This paper revisits visco-elastodynamics from its most standard formulation to some more advanced description involving frequency-dependent damping (or viscosity), analyzing the effects of considering fractional derivatives for representing such viscous contributions. We will prove that such a choice results in richer models that can accommodate different constraints related to the dissipated power, response amplitude and phase angle. Moreover, the use of fractional derivatives allows to accommodate in parallel, within a generalized Kelvin-Voigt analog, many dashpots that contribute to increase the modeling flexibility for describing experimental findings. Finally, the effect of fractional damping in dynamic soil models will be addressed within a seismic site analyses framework.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.01.005
      Issue No: Vol. 98 (2017)
       
  • A comparative analysis of site-specific response spectral amplification
           models
    • Authors: Valerio Poggi; Benjamin Edwards; Donat Fäh
      Pages: 16 - 26
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): Valerio Poggi, Benjamin Edwards, Donat Fäh
      In the framework of the Seismic Hazard Harmonization in Europe (SHARE) project, the Swiss Seismological Service (SED) has performed an evaluation of two procedures developed to produce soil amplification models for 5% damped pseudo-spectral acceleration response spectra, each using different parameters to describe the soil properties. The goal of the work presented here is to evaluate the statistical consistency of the methods, with particular regard to their applicability to engineering practice. Additionally, we compare the results with those from a methodology internally developed by the SED, which is based on spectral modeling of ground motion using the quarter-wavelength approximation to parameterize soil conditions. Soil amplification is computed with respect to reference rock condition as defined for the probabilistic seismic hazard assessment performed during the SHARE project. For the comparison, a residual analysis was performed between the computed soil-amplification functions from the three different methodologies, over a number of selected sites spanning different soil classes and ground motion levels. The analysis of the average residuals of these functions is useful to highlight the main differences between the proposed approaches, with special regard to the impact of soil resonances and anelastic attenuation within different frequency bands. The assessment was performed on a group of 88 selected stations of the Japanese KiKNet strong-motion network, for which complete logs of the shear-wave velocity profiles are available, in addition to a significant number of earthquake recordings. In a first step, average residuals were computed. Subsequently, amplification variability related to soil classes was investigated. The target of this second step was to perform the comparison by separately analyzing the impact of different soil and velocity classes, according to a soil-classification scheme proposed by Aristotle University of Thessaloniki (AUTH). In this paper the main results of these investigations are summarized and, when applicable, an interpretation of our findings is given.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.09.001
      Issue No: Vol. 98 (2017)
       
  • Site amplification at the city scale in Basel (Switzerland) from
           geophysical site characterization and spectral modelling of recorded
           earthquakes
    • Authors: Clotaire Michel; Donat Fäh; Benjamin Edwards; Carlo Cauzzi
      Pages: 27 - 40
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): Clotaire Michel, Donat Fäh, Benjamin Edwards, Carlo Cauzzi
      Hazard assessment at the city scale requires a detailed characterization of the effect of surface geology on ground motion (site effects). Though this analysis is commonly achieved using geophysical site characterization and site response modelling, we propose here a complementary analysis based on amplification functions retrieved from Empirical Spectral Modelling (ESM) of earthquake recordings. We applied this method to the city of Basel (Switzerland) that benefits from a detailed microzonation and a dense Strong Motion Network with 21 modern free-field stations. We first verified the accuracy of ESM amplification functions for this region and used them to determine the bedrock interface at a site with a detailed velocity profile. While the interface between Upper and Lower Tertiary was, until now, considered responsible for the fundamental frequency of resonance in the Rhine Graben, we found that the bedrock interface in fact lies at the Mesozoic limestone. We also investigated the second peak of the H/V ratios that is clustered in a particular area of the basin where amplification is found to be different. We successfully used the ESM amplification functions to verify the microzonation of 2006 and would strongly advise the installation of strong motion stations where such studies are performed in the future. Outside the Rhine Graben, where shallow sediments are found, we propose an amplification functional form based on ESM and the fundamental frequency of resonance. Finally, we combined all our findings and generated amplification maps of the response spectrum at any period of interest for earthquake engineering. This map is proposed for a high resolution real-time implementation in ShakeMap and will be used for seismic loss assessment.
      Graphical abstract image

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.07.005
      Issue No: Vol. 98 (2017)
       
  • Results from shallow geophysical investigations in the northwestern sector
           of the island of Malta
    • Authors: M. Pischiutta; F. Villani; S. D'Amico; M. Vassallo; F. Cara; D. Di Naccio; D. Farrugia; G. Di Giulio; S. Amoroso; L. Cantore; A. Mercuri; D. Famiani; P. Galea; A. Akinci; A. Rovelli
      Pages: 41 - 48
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): M. Pischiutta, F. Villani, S. D'Amico, M. Vassallo, F. Cara, D. Di Naccio, D. Farrugia, G. Di Giulio, S. Amoroso, L. Cantore, A. Mercuri, D. Famiani, P. Galea, A. Akinci, A. Rovelli
      We performed geophysical investigations in the northwestern sector of the island of Malta to reconstruct velocity-depth models and provide shear-wave velocity profiles. We have chosen two sites, one located in Rabat (Malta) and another in the Golden Bay area. We used both active (seismic and electrical 2D-tomography, Multichanel Analysis of Surface Waves – MASW) and passive (2D arrays and single-station measurements using ambient noise) geophysical methods. Consistently with previous studies performed in this part of Malta, we have found that both sites are characterized by site resonance in the frequency range 1–2 Hz as an effect of the local lithostratigraphic succession that shows an impedance contrast at about 60–90 m depth. This resonance effect can have important implications on both seismic hazard as well as seismic risk evaluation of the region since the amplified frequency range coincides with the resonance frequencies typical of 5–10 storey buildings which are very diffuse in the Maltese Islands, especially after intense recent urbanization. We also highlight the importance of performing seismic velocity measurements even at rock sites. As an example, the Golden Bay site would be classified as class “A” following the EuroCode EC8 when considering only the outcropping lithology represented by limestone rocks. Conversely the subsoil characterization provided by this study has revealed that this site falls in the EC8 class “B”, stressing the importance of direct geophysical measurements since the a-priori assignment to A-class could lead to wrong estimates in evaluating the site response.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.10.013
      Issue No: Vol. 98 (2017)
       
  • S-wave velocity measurement and the effect of basin geometry on site
           response, east San Francisco Bay area, California, USA
    • Authors: Koichi Hayashi; Mitchell Craig
      Pages: 49 - 61
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): Koichi Hayashi, Mitchell Craig
      We measured S-wave velocity profiles at eleven sites in the east San Francisco Bay area using surface wave methods. Data acquisition included multichannel analysis of surface waves using an active source (MASW), a passive surface-wave method using a linear array of geophones (Linear-MAM), and a two-station spatial autocorrelation method (2ST-SPAC) using long-period accelerometers. Maximum distance between stations ranged from several hundred meters to several kilometers, depending on the site. Minimum frequency ranged from 0.2 to 2 Hz, depending on the site, corresponding to maximum wavelengths of 10 to 1 km. Phase velocities obtained from three methods were combined into a single dispersion curve for each site. A nonlinear inversion was used to estimate S-wave velocity profiles to a depth of 200–2000 m, depending on the site. Resultant S-wave velocity profiles show significant differences among the sites. On the west side of the Hayward fault and the east side of the Calaveras fault, there is a low velocity layer at the surface, with S-wave velocity less than 700 m/s, to a depth of approximately 100 m. A thick intermediate velocity layer with S-wave velocity ranging from 700 to 1500 m/s lies beneath the low velocity layer. Bedrock with S-wave velocity greater than 1500 m/s was measured at depths greater than approximately 1700 m. Between the Hayward Fault and the Calaveras Fault, thicknesses of the low velocity layer and the intermediate velocity layer are less than 50 m and 200 m respectively, and depth to bedrock is less than 250 m. To evaluate the effect of a lateral change in bedrock depth on surface ground motion due to an earthquake, a representative S-wave velocity cross section perpendicular to the Hayward fault was constructed and theoretical amplification was calculated using a viscoelastic finite-difference method. Calculation results show that the low frequency (0.5–5 Hz) component of ground motion is locally amplified on the west side of the Hayward fault because of the effect of two-dimensional structure.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.07.001
      Issue No: Vol. 98 (2017)
       
  • Surface geology and morphologic effects on seismic site response: The
           study case of Lampedusa, Italy
    • Authors: F. Panzera; G. Lombardo; S. Sicali; S. D'Amico
      Pages: 62 - 72
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): F. Panzera, G. Lombardo, S. Sicali, S. D'Amico
      A joint Italo-Maltese research project (Costituzione di un Sistema Integrato di Protezione Civile Transfrontaliero Italo-Maltese, SIMIT) was financially supported by the European community with the aim to produce hazard maps in the area between the south-eastern Sicilian coast and the Sicily Channel including the islands of Lampedusa and Malta. In the frame of this project, the present study investigates the characteristics of the local seismic response in Lampedusa, a carbonate shelf belonging to the foreland domain at the northern edge of the African plate. Ninety-two ambient noise recordings were collected and processed through spectral ratio techniques. Polarization of the horizontal component of motion was also investigated in order to set into evidence possible directional effects. Results point out that in the central part of the island, where the most ancient and rigid terrains outcrop most of the spectral ratio plots show no particular site effects. On the other hand, nearby morphologic escarpments and fault lines, pronounced spectral ratio peaks in the frequency range 2.0–5.0 Hz are observed. These peaks, as highlighted by polarization analysis, are clearly directional with the largest amplification occurring with high angle (60°–90°) to the structures strike. Moreover, in sites located close to recent and soft deposits outcrops other significant seismic site effects at frequency higher than 5.0 Hz are identified. We can however assert that, rather than the surface lithology, the presence of cliff areas and tectonic structures strongly influence the local amplification of the ground motion and the occurrence of directional effects.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.08.006
      Issue No: Vol. 98 (2017)
       
  • Site - building resonance response in a complex geological setting: Ground
           motions recorded in the centre of Paleohora Basin and at a rock fractured
           outcrop site close to the basin edge (SW Crete, Greece)
    • Authors: Margarita Moisidi
      Pages: 73 - 89
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): Margarita Moisidi
      Seismic site characterization is an important parameter in earthquake hazard assessment for risk mitigation studies, which are essential in engineering design practices and urban planning providing useful information to governmental or private civil protection authorities. Recent advances from site effect studies envisage for the future the importance of incorporating microzonation as a tool for determining resonance prone buildings especially for the most earthquake hazardous municipalities. This study aims to assess the frequencies of vibration of selected masonry and reinforced concrete buildings and to examine potential soil - building resonance in a complex geological setting of the small scale Paleohora Basin (southwest Crete). Ambient noise survey was performed in masonry and reinforced concrete buildings, on soil foundation and on soil at several distances from the base of the selected buildings. The selected public and private (masonry and RC) building constructions are located in the centre of the Basin which is characterized by heterogeneities induced by large scale E-W fault and at rock fractured (of complex orientation and opening of fractures and joints) outcrop site close to the margins of the Basin in the southeast bordered by an NNE-SSW fault. The spatial horizontal to vertical spectral ratio (HVSR) technique using ambient noise reveals that soil-building resonance phenomena could be inferred in the small scale alluvial Paleohora Basin. Two amplified peaks in the centre of the Basin and one amplified peak at the rock fractured outcrop site close to the Basin margins are observed from the data sets. In the centre of the Basin, the amplified peak at medium frequency (3.85–7.11 Hz) is related to the near subsurface irregularities locally induced by E-W faulting, while the low frequency (0.75 Hz) is related to the overlain Quaternary deposits. At the rock fractured outcrop site close to the margins of the Basin the one amplified peak at medium frequencies (2.5 Hz) is related to the fractured limestone outcrop. Weak motion earthquake data following the main earthquake event that occurred near to the southwest coast of Paleohora are recorded in the centre of the Basin (at the schoolyard) and on rock fractured outcrop close to the margins of the Basin. The HVSR of the weak motion earthquake data present in the center of the Basin two amplified peaks at low (0.75 Hz) and medium frequencies (6.56 Hz) and at the rock fractured outcrop site close to the Basin edge one amplified peak at medium frequencies (2.58 Hz). This study conducted in the complex small scale and dense populated Basin, highlights the necessity of incorporating the determination of prone resonance buildings into urban planning for risk mitigation studies, specifically in this earthquake hazardous municipality.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2017.01.007
      Issue No: Vol. 98 (2017)
       
  • Seismic amplification in a fractured rock site. The case study of San
           Gregorio (L'Aquila, Italy)
    • Authors: Deborah Di Naccio; Maurizio Vassallo; Giuseppe Di Giulio; Sara Amoroso; Luciana Cantore; Salomon Hailemikael; Emanuela Falcucci; Stefano Gori; Giuliano Milana
      Pages: 90 - 106
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): Deborah Di Naccio, Maurizio Vassallo, Giuseppe Di Giulio, Sara Amoroso, Luciana Cantore, Salomon Hailemikael, Emanuela Falcucci, Stefano Gori, Giuliano Milana
      The village of San Gregorio (SG), eight kilometres away from L'Aquila (central Italy), was severely damaged by the April 6, 2009 L'Aquila earthquake (MW 6.1). A coseismic fracture zone was mapped along SW-dipping fault segments crossing SG, which is situated at the base of a carbonate relief bounded by the Aterno river alluvial plain. An interdisciplinary approach was used to investigate the seismic response of the area based on geological-structural, geophysical and seismic analyses. We integrated our data with available information from the recent microzonation studies. SG is partly built on alluvial fan deposits constituted by cemented gravel, and partly on jointed carbonate bedrock. An extensive survey of noise measurements showed strong and polarized peaks in the horizontal-to-vertical spectral ratios (H/V), both on soft and rock sites in the 2–10 Hz frequency band. Further, we checked the stability with time of H/V ratios at three sites of SG. An analysis on local earthquakes confirmed the results of noise measurements. To understand the influence of rock mass jointing condition on site effects, we performed structural surveys on carbonate bedrock. We also evaluated the propagation velocities at rock sites using seismic active and seismic dilatometer test (SDMT) surveys. Our analysis showed low values of compressional (VP) and shear wave (VS) velocities of the outcropping rock, where we also observed strong H/V spectral peak and high-density rock fracturing.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.07.004
      Issue No: Vol. 98 (2017)
       
  • A multidisciplinary approach to the seismic characterization of a mountain
           top (Monteluco, central Italy)
    • Authors: F. Durante; G. Di Giulio; M. Tallini; G. Milana; L. Macerola
      Pages: 119 - 135
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): F. Durante, G. Di Giulio, M. Tallini, G. Milana, L. Macerola
      This study provides a seismic characterization of the flat top area of Monteluco carbonate mountain using a multidisciplinary approach. Recordings of ambient vibrations and local earthquakes, geophysical and borehole data, detailed geological surveys and rock mass characterizations were used to investigate the ground-motion amplification observed on the flat top of Monteluco. Weak motion measurements carried out on the top area gave resonance frequency (f0) in the range of 2–4 Hz, likely due to the occurrence of fractured rocks, tens of meters thick. In this frequency range and in the same target area, it was also possible to observe a nearly NW-SE polarization of the seismic signal, which we have tentatively correlated with the main mapped fault systems. Nevertheless, a topographic effect on noise polarization cannot be excluded.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.10.015
      Issue No: Vol. 98 (2017)
       
  • H/V measurements as an effective tool for the reliable detection of
           landslide slip surfaces: Case studies of Castagnola (La Spezia, Italy) and
           Roccalbegna (Grosseto, Italy)
    • Authors: Veronica Pazzi; Luca Tanteri; Gabriele Bicocchi; Michele D'Ambrosio; Andrea Caselli; Riccardo Fanti
      Pages: 136 - 153
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): Veronica Pazzi, Luca Tanteri, Gabriele Bicocchi, Michele D'Ambrosio, Andrea Caselli, Riccardo Fanti
      A variety of methods (detailed geomorphological surveys, geotechnical investigations, local instrumentation, satellite data, and radar interferometry) along with geophysical techniques may be used to investigate slope instabilities and to detect the inhomogeneities of materials as well as their properties, boundaries, and sliding surfaces. Of these techniques, the method based on seismic noise measurements allows abrupt changes in seismic impedance at landslide boundaries resulting from varying levels of seismic velocity and material density to be detected. Peaks of the Horizontal to Vertical Spectral Ratio have proven to serve as effective indicators of the resonance frequency of low-impedance surface layers. In this work, horizontal to vertical spectral ratio surveys of the Castagnola (La Spezia, Italy) and Roccalbegna (Grosseto, Italy) landslides were carried out. From roughly 100 single-station measurements made inside and outside the landslides at each site, we define a threshold number of single-station seismic noise measures beyond which information is redundant because the variation in reconstructed impedance contrast surfaces is not significant. This approach allows one to reliably retrieve the geometry of a landslide body, ultimately generating useful information for determining whether further measurements are needed to improve landslide body reconstruction.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.10.014
      Issue No: Vol. 98 (2017)
       
  • Anomalous behavior of ionospheric parameters above the Kamchatka peninsula
           before and during seismic activity
    • Authors: Vadim V. Bogdanov; Aleksandr V. Kaisin; Aleksey V. Pavlov; Anastasia L. Polyukhova; Claudia-Veronika Meister
      Pages: 154 - 160
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): Vadim V. Bogdanov, Aleksandr V. Kaisin, Aleksey V. Pavlov, Anastasia L. Polyukhova, Claudia-Veronika Meister
      In the present work, searching for new methods of earthquake prediction, variations of ionospheric plasma parameters and ionospheric turbulence before and during seismic activity are studied applying complex radiophysical methods and a theoretical probabilistic approach. The analysis of radiophysical observations of some seismic events of February–March (28.02.–02.03.) 2013 shows, that K-layer formation (appearance of a corpuscular layer due to precipitation of particles from the radiation belts), E s - and F-spread effects as well as an increase of the critical f o F2-frequency occurred about one day before earthquakes with a magnitude M ≥ 6.5. F2-spread was even observed at low geomagnetic activity. One seismic shock was preceded by an abnormal increase in the value of the critical frequency f o F2, and about 2 h after the shock, f o F2 was again well below the median value although a geomagnetic storm happened. Therefore, it may be concluded that, in future, variations of ionospheric plasma parameters and turbulence may be used as additional tool to determine the magnitude of preparing strong earthquakes. The propabilistic method which is applied in the present work is already described in (Bogdanov et al., J. Volcanology and Seismology, 4(6), 412–422, 2010). It allowed to detect a growth of seismic activity in the Kamchatka region in 2013.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2016.04.002
      Issue No: Vol. 98 (2017)
       
  • Detecting CO2 anomalies in a spring on Mt. Amiata volcano (Italy)
    • Authors: L. Pierotti; F. Gherardi; G. Facca; L. Piccardi; G. Moratti
      Pages: 161 - 172
      Abstract: Publication date: April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 98
      Author(s): L. Pierotti, F. Gherardi, G. Facca, L. Piccardi, G. Moratti
      Located at the south-western slope of the Mt. Amiata volcano (Tuscany, Central Italy), the Bagnore spring has been investigated for geochemical precursors of earthquakes from 2004 to 2015. Over this period, several parameters of the spring have been monitored by discrete and continuous sampling. An automatic continuous monitoring station, equipped with sensors for the measurement of temperature, pH, redox potential, electrical conductivity, CO2 and CH4 dissolved concentration, is transmitting the registered signals to the remote server in Pisa 150 km northwest of Mt. Amiata. The Bagnore spring drains a shallow, short-circuiting aquifer hosted in the volcanic rocks of the volcano. Its emergence point is located in proximity of the intersection of two major fault systems that are supposed to provide a preferential ascent path to hydrothermal gases, mainly represented by C O 2 ( g ) and H 2 S ( g ) , locally rising from depth. The most evident change occurred in the registered signals over the period is represented by the sudden increase in CO2 concentration measured starting from April 2010. Along with this increase in CO2, a slight increase in water temperature and in S O 4 concentration, associated to a decrease in pH, was also recorded. This trend has been interpreted as an evidence for the augmented inflow of deep gases into the shallow aquifer. The CO2 continuous signal recorded by the Bagnore automatic station has been then processed by applying multiple statistical techniques (i.e. artificial neural network analysis and Census I method) in the search for anomalies possibly related to local seismic activity. Anomalous signals have been detected starting from April 24, 2010, and the correlation with the most energetic seismic events has been tentatively proposed.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2017.01.008
      Issue No: Vol. 98 (2017)
       
  • Reactive transport modelling of cement-groundwater-rock interaction at the
           Grimsel Test Site
    • Authors: M. Carme Chaparro; Maarten W. Saaltink; Josep M. Soler
      Abstract: Publication date: Available online 13 May 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M. Carme Chaparro, Maarten W. Saaltink, Josep M. Soler
      An in situ experiment at the Grimsel Test Site (Switzerland) to study water-cement-rock interaction in fractured granite was modelled. It consisted of a hardened cement source in a borehole intersecting a water conducting fracture. Grimsel groundwater was injected into this borehole. Two other boreholes at about 0.56 m and 1.12 m from the emplacement borehole were used to monitor the evolution of water composition for 5 years. The modelling approach was based on a 1D radial model for the emplacement borehole and a small volume of rock (fault gouge) around it, and a 2D model for the rest of the domain. The results of the 1D model were used as input for the 2D model. Both models showed dissolution of the fault gouge minerals. Results from the 1D model showed dissolution of portlandite in the cement with an increase in porosity. The 2D model showed a reduction in porosity in the fault gouge due to mineral precipitation. Near the emplacement borehole ettringite precipitated. At the centre of the plume there was precipitation of C-A-S-H and hydrotalcite. At the edge of the hyperalkaline plume calcite, hydrotalcite and illite precipitated.

      PubDate: 2017-05-18T05:40:43Z
      DOI: 10.1016/j.pce.2017.05.006
       
  • The urbanization efficiency in Chengdu City: An estimation based on a
           three-stage DEA model
    • Authors: Siqi Jia; Chengxin Wang; Yifan Li; Fan Zhang; Wei Liu
      Abstract: Publication date: Available online 12 May 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Siqi Jia, Chengxin Wang, Yifan Li, Fan Zhang, Wei Liu
      With economic development and population growth occurring throughout China, there has been increasing conflicts between resources, environmental protection and economic development in many regions, especially in the developed regions. Therefore, it is important to correctly evaluate the pressure of human activities on the natural environment and the ecosystem carrying capacity at a regional scale. This paper evaluated the urbanization efficiency based on the three-stage Data Envelopment Analysis (DEA) model, which takes the impacts of exogenous factors on the urbanization rate into consideration. From the perspectives of governmental management and urban growth and scale, this paper indicated the current urbanization mode and features in Chengdu based on land use data, socioeconomic and natural data in each district and county. The results show that Jinjiang, Longquanyi, Qingbaijiang, Qingyang districts, Pujiang, Xinjin counties and Dujiangyan county-level city are always with the balanced urbanization efficiency; while the efficiency in Dayi, Pi counties, Chongzhou, Pengzhou, Qionglai county-level cities and Jinniu, Chenghua districts still needs to be improved; and Shuangliu and Jintang counties keep the lowest urbanization level. Overall, the average reduction rate in built-up area in highest at 29.57% among the three input indicators (land, capital and labor), which means that the superfluous area of built-up land hinders the balanced development of urbanization in Chengdu. It also suggests that three-stage DEA model is effective to reflect the realistic level of urbanization efficiency by eliminating environmental impact. Finally, this paper further provides improved directions and policy suggestions for the sustainable and well-rounded urban development.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2017.05.003
       
  • Set pair analysis method for coordination assessment in water resources
           utilizing conflict
    • Authors: Zhengwei Pan; Yanhua Wang; Juliang Jin; Xiaowei Liu
      Abstract: Publication date: Available online 12 May 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Zhengwei Pan, Yanhua Wang, Juliang Jin, Xiaowei Liu
      In order to describe management problems of water resource system conflicts quantitatively, six elements were proposed in the management of water resources conflicts, which are coordination participator, coordination goal, coordination index, behavioral strategies, coordination situation and coordination rule. In the coordination management of conflicts in water resource systems a coordination index has a lower limiting value meeting the coordination participator interests, and has an upper limiting value for ensuring the interests of the overall system and other coordination participators. When the coordination index value exceeds the limiting range, the interests of the overall system and other coordination participators cannot be guaranteed. The coordination indexes of water resources conflict are interval numbers. According to the characteristics of interval pattern indexes, the bidirectional connection number was proposed to describe the coordination degree. Based on the bidirectional connection number, the coordination evaluation method was developed, and was used in the coordination evaluation of water resource conflicts in the Yellow River basin. The results showed that the coordination status of water resources utilization was generally acceptable. However, with increasing water consumption in some provinces in the Yellow River basin in recent years, the available water supply cannot meet the allocation plan for water resource supply. The coordination degree of water resources utilization has, therefore, been declining.

      PubDate: 2017-05-13T05:19:01Z
      DOI: 10.1016/j.pce.2017.05.009
       
  • Transport properties evolution of cement model system under degradation -
           Incorporation of a pore-scale approach into reactive transport modelling
    • Authors: N. Seigneur; E. L’Hôpital; A. Dauzères; J. Sammaljavi; M. Voutilainen; P.E. Labeau; A. Dubus; V. Detilleux
      Abstract: Publication date: Available online 6 May 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): N. Seigneur, E. L’Hôpital, A. Dauzères, J. Sammaljavi, M. Voutilainen, P.E. Labeau, A. Dubus, V. Detilleux
      This paper describes a multi-scale approach for the modelling of the degradation of model cement pastes using reactive transport. It specifically aims at incorporating chemistry-transport feedback results from a pore-scale approach into a continuum description. Starting from a numerical representative elementary volume of the model cement paste, which was built according to extensive experimental dedicated chacarterizations, this paper provides three separate descriptions of two different degradations: leaching and carbonation. First, 2D pore-scale simulations are performed and predict degradation depths in very good agreement with experiments. Second, 3D pore scale descriptions of how the microstructre evolves provides accurate description of the evolution of transport properties through degradation. Finally, those latter results are incorporated as a feedback law between porosity and effective diffusion coefficient into a 1D continuum approach of reactive transport. This paper provides pore-scale explanations of why reactive transport modelling has encountered mitigated success when applied to cementitious materials, especially during carbonation or degradations consisting of precipitation reactions. In addition to that, different degradation modellings are in very good agreement with experimental observations.

      PubDate: 2017-05-08T04:45:44Z
      DOI: 10.1016/j.pce.2017.05.007
       
  • A sorption model for alkalis in cement-based material – Correlations
           with solubility and electrokinetic properties
    • Authors: Pierre Henocq
      Abstract: Publication date: Available online 5 May 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Pierre Henocq
      In cement-based materials, radionuclide uptake is mainly controlled by calcium silicate hydrates (C-S-H). This work presents an approach for defining a unique set of parameters of a surface complexation model describing the sorption behavior of alkali ions on the C-S-H surface. Alkali sorption processes are modeled using the CD-MUSIC function integrated in the Phreeqc V.3.0.6 geochemical code. Parameterization of the model was performed based on (1) retention, (2) zeta potential, and (3) solubility experimental data from the literature. This paper shows an application of this model to sodium ions. It was shown that retention, i.e. surface interactions, and solubility are closely related, and a consistent sorption model for radionuclides in cement-based materials requires a coupled surface interaction/chemical equilibrium model. In case of C-S-H with low calcium-to-silicon ratios, sorption of sodium ions on the C-S-H surface strongly influences the chemical equilibrium of the C-S-H + NaCl system by significantly increasing the aqueous calcium concentration. The close relationship between sorption and chemical equilibrium was successfully illustrated by modelling the effect of the solid-to-liquid ratio on the calcium content in solution in the case of C-S-H + NaCl systems.

      PubDate: 2017-05-08T04:45:44Z
      DOI: 10.1016/j.pce.2017.05.004
       
  • Estimating policy pressure for China's cultivated land use protection
           based on an extended index
    • Authors: Jiandong Chen; Shulei Cheng; Malin Song
      Abstract: Publication date: Available online 5 May 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Jiandong Chen, Shulei Cheng, Malin Song
      Based on existing references, using the decomposition technique of the second model of the logarithmic mean Divisia index (LMDI) decomposition method and the principle of “jointly created and equally distributed” of the Refined Laspeyres (RL) index, this paper developed a new policy pressure index and applied it to estimate the policy pressure for China's cultivated land use protection. The results indicated that, first, the policy pressure for China's cultivated land use protection experienced an inverted U–shaped evolution from 1997 to 2014 and that the status of cultivated land use protection policy pressure in each province was related mainly to local economic development and industrial structure. Second, agricultural production efficiency and industrial structure exerted positive influences on policy pressure for cultivated land use protection, but economic scale exerted negative influences on it. Third, the differences among areas with different policy pressures were explained mainly by two factors: the economic scale and agricultural production efficiency. The former exerted a positive and the latter a negative influence.

      PubDate: 2017-05-08T04:45:44Z
      DOI: 10.1016/j.pce.2017.05.002
       
  • Modelling of Chemical Degradation of Blended Cement-based Materials by
           Leaching Cycles with Callovo-Oxfordian Porewater
    • Authors: Javier Olmeda; Pierre Henocq; Eric Giffaut; Mireia Grivé
      Abstract: Publication date: Available online 4 May 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Javier Olmeda, Pierre Henocq, Eric Giffaut, Mireia Grivé
      The present work describes a thermodynamic model based on pore water replacement cycles to simulate the chemical evolution of blended cement (BFS + FA) by interaction with external Callovo-Oxfordian (COx) pore water. In the framework of the radioactive waste management, the characterization of the radionuclide behaviour (solubility/speciation, adsorption) in cementitious materials needs to be done for several chemical degradation states (I to IV). In particular, in the context of the deep geological radioactive waste disposal project (Cigéo), cement-based materials will be chemically evolved with time in contact with the host-rock (COx formation). The objective of this study is to provide an equilibrium solution composition for each degradation state for a CEM-V cement-based material to support the adsorption and diffusion experiments reproducing any state of degradation. Calculations have been performed at 25 ºC using the geochemical code PhreeqC and an up-to-date thermodynamic database (ThermoChimie v.9.0.b) coupled to SIT approach for ionic strength correction. The model replicates experimental data with accuracy. The approach followed in this study eases the analysis of the chemical evolution in both aqueous and solid phase to obtain a fast assessment of the geochemical effects associated to an external water intrusion of variable composition on concrete structures.

      PubDate: 2017-05-08T04:45:44Z
      DOI: 10.1016/j.pce.2017.05.008
       
  • Adsorption of gluconate and uranyl on C-S-H phases: Combination of wet
           chemistry experiments and molecular dynamics simulations for the binary
           systems
    • Authors: Iuliia Androniuk; Catherine Landesman; Pierre Henocq; Andrey G. Kalinichev
      Abstract: Publication date: Available online 4 May 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Iuliia Androniuk, Catherine Landesman, Pierre Henocq, Andrey G. Kalinichev
      As a first step in developing better molecular scale understanding of the effects of organic additives on the adsorption and mobility of radionuclides in cement under conditions of geological nuclear waste repositories, two complementary approaches, wet chemistry experiments and molecular dynamics (MD) computer simulations, were applied to study the sorption behaviour of two simple model systems: gluconate and uranyl on calcium silicate hydrate phases (C-S-H) – the principal mineral component of hardened cement paste (HCP). Experimental data on sorption and desorption kinetics and isotherms of adsorption for gluconate/C-S-H and U(VI)/C-S-H binary systems were collected and quantitatively analysed for C-S-H samples synthesized with various Ca/Si ratios (0.83, 1.0, 1.4) corresponding to various stages of HCP aging and degradation. Gluconate labelled with 14C isotope was used in order to improve the sensitivity of analytical detection technique (LSC) at particularly low concentrations (10−8–10−5 mol/L). There is a noticeable effect of Ca/Si ratio on the gluconate sorption on C-S-H, with stronger sorption at higher Ca/Si ratios. Sorption of organic anions on C-S-H is mediated by the presence of Ca2+ at the interface and strongly depends on the surface charge and Ca2+ concentration. In parallel, classical MD simulations of the same model systems were performed in order to identify specific surface sorption sites most actively involved in the sorption of gluconate and uranyl on C-S-H and to clarify molecular mechanisms of adsorption.

      PubDate: 2017-05-08T04:45:44Z
      DOI: 10.1016/j.pce.2017.05.005
       
  • Ecological security assessment based on ecological footprint approach in
           Beijing-Tianjin-Hebei region, China
    • Authors: Xi Chu; Xiangzheng Deng; Gui Jin; Zhan Wang; Zhaohua Li
      Abstract: Publication date: Available online 4 May 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xi Chu, Xiangzheng Deng, Gui Jin, Zhan Wang, Zhaohua Li
      Recently, researcher have been extensively using ecological footprint to quantitatively measure human pressure on ecosystems. This paper put forward ecological tension index (ETI), ecological occupancy index (EOI) and ecological economic coordination index (EECI) to evaluate ecological security of the Beijing-Tianjin-Hebei (BTH) region between 1995 and 2010. The results came as follows. (1) The ecological footprint of BTH region was increased, while the carrying capacity (biocapacity) of the terrestrial ecosystem was decreased. This led the region to a serious ecological deficit that was increased by 1.77 times. (2) ETI level of the region was found very risky. EOI level fluctuated from poor to moderately poor, indicating that rapid economic development has pressurized the ecosystem. EECI level indicated a very poor coordination between economic development and ecosystem conservation. (3) As to the indices results for sub-regions, ETI level in Tianjin was evaluated very risky, in Beijing it was changed from risky to very risky, while in Hebei it was changed from very risky to risky. EOI level in Beijing was changed from moderately poor to poor, keeping poor for long time. However, the EOI level in Tianjin and Hebei was found opposite to Beijing. It was changed from poor to moderately poor. While EECI level of Beijing, Tianjin and Hebei was found very poor, meaning economic development and ecosystem conservation are maintained imbalanced. This study finally concludes that whether the whole region or the sub-regions, their existing development patterns were unsustainable, and ecological security situation was serious.

      PubDate: 2017-05-08T04:45:44Z
      DOI: 10.1016/j.pce.2017.05.001
       
  • Factors influencing sustainability of communally-managed water facilities
           in rural areas of Zimbabwe
    • Authors: T. Kativhu; D. Mazvimavi; D. Tevera; I. Nhapi
      Abstract: Publication date: Available online 29 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): T. Kativhu, D. Mazvimavi, D. Tevera, I. Nhapi
      Sustainability of point water facilities is a major development challenge in many rural settings of developing countries not sparing those in the Sub-Saharan Africa region. This study was done in Zimbabwe to investigate the factors influencing sustainability of rural water supply systems. A total of 399 water points were studied in Nyanga, Chivi and Gwanda districts. Data was collected using a questionnaire, observation checklist and key informant interview guide. Multi-Criteria analysis was used to assess the sustainability of water points and inferential statistical analysis such as Chi square tests and Analysis of Variance (ANOVA) were used to determine if there were significant differences on selected variables across districts and types of lifting devices used in the study area. The thematic approach was used to analyze qualitative data. Results show that most water points were not functional and only 17% across the districts were found to be sustainable. A fusion of social, technical, financial, environmental and institutional factors was found to be influencing sustainability. On technical factors the ANOVA results show that the type of lifting device fitted at a water point significantly influences sustainability (F=37.4, p< 0.01). Availability of spare parts at community level was found to be determining the downtime period of different lifting devices in the studied wards. Absence of user committees was found to be central in influencing sustainability as water points that did not have user committees were not sustainable and most of them were not functional during the time of the survey. Active participation by communities at the planning stage of water projects was also found to be critical for sustainability although field results showed passive participation by communities at this critical project stage. Financial factors of adequacy of financial contributions and establishment of operation and maintenance funds were also found to be of great importance in sustaining water supply systems. It is recommended that all factors should be considered when assessing sustainability since they are interrelated.

      PubDate: 2017-05-02T04:14:40Z
      DOI: 10.1016/j.pce.2017.04.009
       
  • Dispersion of inorganic contaminants in surface water in the vicinity of
           Potchefstroom
    • Authors: A. Manyatshe; E. Fosso-Kankeu; D. van der Berg; N. Lemmer; F. Waanders; H. Tutu
      Abstract: Publication date: Available online 27 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A. Manyatshe, E. Fosso-Kankeu, D. van der Berg, N. Lemmer, F. Waanders, H. Tutu
      Potchefstroom and the neighbouring cities rely mostly on the Mooi River and Vaal River for their water needs. These rivers flow through the gold mining areas and farms, and are therefore likely to be contaminated with substantial amounts of inorganic pollutants. Water was collected along the rivers network, streams, canals and dams in Potchefstroom and the vicinity. The samples were characterized for geochemical parameters, metals and anions concentrations. The results showed high concentrations of potentially toxic elements such as As (4.53 mg/L – 5.74 mg/L), Cd (0.25 mg/L – 0.7 mg/L), Pb (1.14 mg/L – 5.13 mg/L) and U (0.04 mg/L – 0.11 mg/L) which were predominantly found around the mining areas. Elevated concentrations of anions such SO4 2- and CN- were detected around mining areas while NO3 - was dominant near farms. The relatively high levels of anions and metals in the surface water made it unfit for domestic or agricultural use. The study showed that contaminants in mining and agricultural facilities were potentially mobilised, thus impacting the nearby water systems.

      PubDate: 2017-05-02T04:14:40Z
      DOI: 10.1016/j.pce.2017.04.008
       
  • Water Security for Productive Economies: Applying an Assessment Framework
           in southern Africa
    • Authors: Bunyod Holmatov; Jonathan Lautze; Herath Manthrithilake; Ian Makin
      Abstract: Publication date: Available online 27 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Bunyod Holmatov, Jonathan Lautze, Herath Manthrithilake, Ian Makin
      Achieving water security has emerged as a major objective in Africa, yet an analytical or diagnostic framework for assessing water security in African countries is not known to exist. This paper applies one key dimension of the 2016 Asian Development Bank’s (ADB) Asian Water Development Outlook (AWDO) to assess levels of water security for productive economies in countries of the Southern African Development Community (SADC). Economic aspects of water security cover four areas: economic activities in the broad sense, agriculture, electricity, and industry. Water security in each area is measured through application of a set of indicators; results of indicator application are then aggregated to determine economic water security at a country-level. Results show that economic water security in SADC is greatest in the Seychelles and South Africa, and lowest in Madagascar and Malawi. Opportunities for strengthening economic water security in the majority of SADC countries exist through improving agricultural water productivity, strengthening resilience, and expanding sustainable electricity generation. More profoundly, this paper suggests that there is clear potential and utility in applying approaches used elsewhere to assess economic water security in southern Africa.

      PubDate: 2017-05-02T04:14:40Z
      DOI: 10.1016/j.pce.2017.04.007
       
  • Determination of Toxic Metals in Drinking Water Sources in the Chief
           Albert Luthuli Local Municipality in Mpumalanga, South Africa
    • Authors: Lebea N. Nthunya; Monaheng L. Masheane; Soraya P. Malinga; Edward N. Nxumalo; Bhekie B. Mamba; Sabelo D. Mhlanga
      Abstract: Publication date: Available online 26 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Lebea N. Nthunya, Monaheng L. Masheane, Soraya P. Malinga, Edward N. Nxumalo, Bhekie B. Mamba, Sabelo D. Mhlanga
      This study was conducted to determine the presence and levels of toxic metals on selected water sources in a rural community in Lochiel, South Africa. Collection of water samples from identified drinking water sources (open wells, community tanks, water treatment works and boreholes) was done in all seasons of the year (winter, spring, summer and autumn) between 2014 and 2015. The concentrations of identified toxic metals (cobalt, chromium, copper, lead, zinc, manganese and iron) were measured using ICP-OES. Some water sources were found to contain concentrations of toxic metals at levels slightly higher than USEPA, WHO and SANS241 set limits (e.g. manganese and cobalt), while others were found to be within the acceptable limits. This suggested that the residents residing in locations that have water sources containing toxic metals at the concentrations above the set limits are at risk and susceptible to suffer diseases caused by these toxic metals. The side effects of the metals may not be acute; however prolonged exposure to the toxic metals may result in detrimental effects since they are known to bioaccumulate in the body.

      PubDate: 2017-05-02T04:14:40Z
      DOI: 10.1016/j.pce.2017.04.006
       
  • Short-term effects of tidal flooding on soil nitrogen mineralization in a
           Chinese tidal salt marsh
    • Authors: Haifeng Gao; Junhong Bai; Xiaoya Deng; Qiongqiong Lu; Xiaofei Ye
      Abstract: Publication date: Available online 26 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Haifeng Gao, Junhong Bai, Xiaoya Deng, Qiongqiong Lu, Xiaofei Ye
      Tidal flooding is an important control of nitrogen biogeochemistry in wetland ecosystems of Yellow River Delta, China. Variations in hydrology could change soil redox dynamics and conditions for microorganisms living. A tidal simulation experiment was designed to extract tidal flooding effect on nitrogen mineralization of salt marsh soil. Inorganic nitrogen and relevant enzyme were measured during the 20-day incubation period. Considering the variation of both inorganic N and enzymes, nitrogen mineralization process in tidal salt marsh could be divided into 2 phases of short term response and longtime adaption by around 12th incubation day as the inflection point. Soil ammonium nitrogen (NH4 +-N) and volatilized ammonia (NH3) occupied the mineralization process since nitrate nitrogen (NO3 --N) was not detected over whole incubation period. NH4 +-N varied fluctuant and increased significantly after 12 day’s incubation. Released NH3 reached to peak value of 14.24 mg m-2 d-1 at the inflection point and declined thereafter. Inorganic nitrogen released according to net nitrogen mineralization rate (RM) under the tidal flooding condition without plant uptake except first 2 days. However, during the transitional period of 6 to 12 days, RM decreased notably to almost 0 and increased again after inflection point with the value of 0.182 mg kg-1 d-1. It might be due to the change of microbial composition and function when soil shifted from oxic to anoxic, which were reflected by arylamidase, urease and fluorescein diacetate. Fluorescein diacetate hydrolysis and arylamidase had the similar variation of U style with decreasing activities before 12 days’ incubation. All the enzymes measured in this experiment increased after inflection point. Whereas, urease activity kept constant from 2 to 12 days. Alternant oxidation reduction condition would increase N loss through denitrification and ammonia volatilization during the transitional period, while more inorganic nitrogen would be available in reductive environment of long-term tidal flooding. Therefore, hydrological process regulation has great influence on nitrogen cycling and further influence on wetland productivity.

      PubDate: 2017-05-02T04:14:40Z
      DOI: 10.1016/j.pce.2017.04.002
       
  • Emergy analysis on urban metabolism by counties in Beijing
    • Authors: Wei Qi; Xiangzheng Deng; Xi Chu; Chunhong Zhao; Fan Zhang
      Abstract: Publication date: Available online 6 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Wei Qi, Xiangzheng Deng, Xi Chu, Chunhong Zhao, Fan Zhang
      Beijing is an international metropolis, with rapid urbanization during the last 30 years. However, it faces the challenge of sustainability with limited natural resources. This paper attempts to incorporate emergy analysis on urban metabolism to investigate the sustainability of the entire Beijing at the county level. Based on the time-series climate data and socioeconomic data, we calculated the structure, intensities, environment pressures and output efficiency of the urban metabolic emergy system by counties between 2005 and 2014. The result shows that the metabolic emergy stores of Beijing, especially in Capital Function Core (CFC) area, had been increasing significantly during the study period, especially for the increasing imported and exported emergy accounting. The 16 districts of Beijing can be grouped into four types of functional areas in terms of the function in urban metabolism. The five parts of urban metabolic emergy system had obviously spatial difference by counties, and the renewable emergy in CFC area and Urban Function Development (UFD) zone was obviously lower than in City Development (CD) zone and Ecological Conservation Development (ECD) area. The non-renewable emergy and waste emergy in CFC area, UFD zone and CD zone were obviously higher than that in ECD area. The imported emergy and exported emergy were significantly higher in Dongcheng, Xicheng and Chaoyang district. Emergy use intensities of CFC area had been increasing with the rapid rise in imported emergy and exported emergy, resulting in the increasing environmental pressure. However, the district governments of CFC area are trying to enhance output efficiency and sustainability to reduce waste emergy. The indices of EYR and ESI had been gradually decreasing and the region with the highest value of ESI and EYR, in decreasing order, are: ECD area, CD zone, UFD zone, and CFC area. The result indicates that CFC area is more fragile and dependent on external resources. Therefore, the Beijing government, especially the district governments of CFC area should encourage the exploitation and utilization of renewable resources and energy, increase the consumption efficiency of non-renewable resources and energy, and establish the mechanism to re-use wastes of resources and energy in order to promote the urban metabolism.

      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.01.024
       
  • Soil carbon, nitrogen, and phosphorus stoichiometry of three dominant
           plant communities distributed along a small-scale elevation gradient in
           the East Dongting Lake
    • Authors: Cong Hu; Feng Li; Yong-hong Xie; Zheng-miao Deng; Xin-sheng Chen
      Abstract: Publication date: Available online 4 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Cong Hu, Feng Li, Yong-hong Xie, Zheng-miao Deng, Xin-sheng Chen
      Soil carbon (C), nitrogen (N), and phosphorus (P) stoichiometry greatly affects plant community succession and structure. However, few studies have examined the soil stoichiometric changes in different vegetation communities of freshwater wetland ecosystems along an elevation gradient distribution. In the present study, soil nutrient concentrations (C, N, and P), soil stoichiometry (C:N, C:P, and N:P ratios), and other soil physicochemical characteristics were measured and analyzed in 62 soil samples collected from three dominant plant communities (Carex brevicuspis, Artemisia selengensis, and Miscanthus sacchariflorus) in the East Dongting Lake wetlands. The concentration ranges of soil organic carbon (SOC), total soil nitrogen (TN), and total soil phosphorus (TP) were 9.42–45.97 g/kg, 1.09–5.50 g/kg, and 0.60–1.70 g/kg, respectively. SOC and TN concentrations were the highest in soil from the C. brevicuspis community (27.48 g/kg and 2.78 g/kg, respectively) and the lowest in soil from the A. selengensis community (17.97 g/kg and 1.71 g/kg, respectively). However, the highest and lowest TP concentrations were detected in soil from the A. selengensis (1.03 g/kg) and M. sacchariflorus (0.89 g/kg) communities, respectively, and the C:N ratios were the highest and lowest in soil from the M. sacchariflorus (12.72) and A. selengensis (12.01) communities, respectively. C:P and N:P ratios were the highest in soil from the C. brevicuspis community (72.77 and 6.46, respectively) and the lowest in soil from the A. selengensis community (45.52 and 3.76, respectively). Correlation analyses confirmed that SOC concentrations were positively correlated with TN and TP, and C:N and N:P ratios were positively correlated with C:P. These data indicated that soil C, N, and P stoichiometry differed significantly among different plant communities and that these differences might be accounted for by variations in the hydrological conditions of the three communities.

      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.04.001
       
  • Vertical distribution of mercury and MeHg in Nandagang and Beidagang
           wetlands: Influence of microtopography
    • Authors: Ruhai Liu; Yanyan Zhang; Yan Wang; Jin Zhao; Huayao Shan
      Abstract: Publication date: Available online 4 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Ruhai Liu, Yanyan Zhang, Yan Wang, Jin Zhao, Huayao Shan
      Wetlands often show different small-scale topography, such as riffle, habitat island, deep water, shallow water zone and dry zone. Core soils in different micro topographical landforms of Nandagang and Beidagang wetlands in North China were sampled for THg and MeHg to analyze the influence of microtopography. Results showed that THg content in surface soil (<2 cm) was little higher than that at depth 2–4 cm of all stations. There were several peaks in the profile, which reflected mercury pollution in past. High THg content in undisturbed natural wetland soil implied accumulation of mercury. Harvest of plant, drained water decreased the accumulation of mercury in wetlands. Water level caused by microtopography affected the production of MeHg. Depth of the highest MeHg content decreased from N1, N2, N6, N3 to N4 following the increase of water level. Plant type and coverage also affected the vertical distribution of MeHg. More detailed profiles of MeHg, organic matter and total phosphorus in different sites show strong differences in soil chemistry, suggesting a complex interplay among hydrology, biogeochemistry and microtopography.

      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.04.003
       
  • Effects of soil abiotic factors on the plant morphology in an intertidal
           salt marsh, Yellow River Delta, China
    • Authors: Shanze Li; Baoshan Cui; Junhong Bai; Tian Xie; Jiaguo Yan; Qing Wang; Shuyan Zhang
      Abstract: Publication date: Available online 4 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Shanze Li, Baoshan Cui, Junhong Bai, Tian Xie, Jiaguo Yan, Qing Wang, Shuyan Zhang
      Plant morphology plays important role in studying biogeography in many ecosystems. Suadea salsa, as a native plant community of northern China and an important habitat for diversity of waterbirds and macrobenthos, has often been overlooked. Nowadays, S. salsa community is facing great loss due to coastal reclamation activities and natural disturbances. To maintain and restore S. salsa community, it's important to address the plant morphology across marsh zones, as well as its relationships with local soil abiotic conditions. In our studied intertidal salt marsh, we found that less flood disturbance frequency, softer soil conditions, rich soil organic matter, total carbon and total nitrogen, lower water depth and water content, less species competition will benefit S. salsa plant in the morphology of high coverage, above-ground biomass, shoot height and leaf length. Lower soil porewater salinity will benefit the below-ground biomass of S. salsa. Thus, we recommend managers help alleviate soil abiotic stresses in the intertidal salt marshes, making the soil conditions more suitable for S. salsa growth and succession.

      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.04.004
       
  • Impacts of water scarcity on social economic development: A case study of
           Gaotai County, China
    • Authors: Qing Zhou; Xiangzheng Deng; Feng Wu
      Abstract: Publication date: Available online 3 April 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Qing Zhou, Xiangzheng Deng, Feng Wu
      Provisioning services for socio-economic development is an important hydrological ecosystem services human obtains from freshwater. The dilemma between water scarcity and economic development in arid regions influence water utilization among different sectors. A water resource embedded Social Accounting Matrix (WSAM) helps to analyze the interrelation between water resource utilization and social economic development. In this paper, by establishing the WSAM and applying SAM multiplier and decomposition analysis in Gaotai County northwestern China to explore the economic structure and the feedback mechanism and water flows among different sectors, we found that though agriculture is less productive than the second industry due to its low development stage and lack of deep processing chain, as the dominated sector, it still plays the most important part in the whole national economy in the study area. Considering the strategic location of Gaotai county, which is an important hub in the One Belt and One Road economic zone, different economic development scenarios were modeled. Analysis shows that expanding agricultural exports can promote rural employment and improve rural household welfare, but will also lead to water resources outflow and aggravate the water conflicts among different water users. In order to simulate the water price reform effects, the price multiplier was calculated to measure the social economic effects of the irrigation water price reform on the whole economic system. Results indicate that the price of agriculture products, industrial products, and price of labour will increase by 0.03, 0.018 and 0.005 units respectively when water price increase by one unit. And the Consumer Price Index (CPI) will increase by 0.005 units.

      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.03.009
       
  • Optimization of land-use management for ecosystem service improvement: A
           review
    • Authors: Gui Jin; Xiangzheng Deng; Xi Chu; Zhihui Li; Yuan Wang
      Abstract: Publication date: Available online 23 March 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Gui Jin, Xiangzheng Deng, Xi Chu, Zhihui Li, Yuan Wang
      Land use is closely related to human activity, which affect ecosystem services by changing the types, patterns and ecological processes of ecosystem, and consequently impact the human well-being. Scientific simulation is needed to analyze the land use policy impacts on ecosystem services and socioeconomic development. Based on the reviews, the Computable General Equilibrium (CGE) model plays an important role in building simulation framework for land-use management optimization for ecosystem services improvement, which can be used to systematically analyze changes of ecosystem service driven by land use change as well as the consequent impacts on socioeconomic development. In addition, the similarities and differences between the CGE model and System Dynamics (SD) model are identified. CGE and SD models have their advantages and disadvantages, a suitable model can be select in the practice of policy simulation. In this sense, these simulation models are of great significance to decision-making on land-use management measures for ecosystem service conservation and socioeconomic development.

      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.03.003
       
  • Impacts of land use/cover change on terrestrial carbon stocks in Uganda
    • Authors: Fan Zhang; Jinyan Zhan; Qian Zhang; Lina Yao; Wei Liu
      Abstract: Publication date: Available online 18 March 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Fan Zhang, Jinyan Zhan, Qian Zhang, Lina Yao, Wei Liu
      Land use/cover change, especially conversion and degradation of forest land, is the key factor causing terrestrial carbon stocks declines in Uganda. How local ecological assemblages are responding is less clear—a concern given their importance for many ecosystem functions and services. The main objectives are to assess status and variation in carbon stocks across land covers and quantify spatial distribution and dynamic variation of terrestrial carbon stocks in response to land use/cover change. This paper presents a methodology for quantifying and assessing changes in carbon stocks as a result of land use change using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. The model was used to map and quantify carbon stocks for Uganda for 2006 and 2010 land use conditions. Our result showed that the total carbon stocks have a sharp decline from 2.42 billion Tg C in 2006 to 1.72 billion Tg C in 2010 in aboveground, belowground and soil. During 2006 to 2010, losses in carbon stocks from land use and land cover were 705.59 million Tg C. To be more specific, estimated carbon stocks in Uganda decreased 849.94 million Tg C because forest land changed to other land use and covers. Cultivated land change, which is from other types of land, resulting in carbon stocks decreased 71.11 million Tg C, and estimated carbon stocks increased 177.34 million Tg C with grassland changed to other land use and covers. Finally, we suggested potential policy measures to mitigate negative effects of land use and cover change on carbon stocks in Uganda.

      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.03.005
       
  • Soft X-ray absorption near-edge investigations of Mg-containing mineral
           phases relevant for cementitious materials
    • Authors: M. Vespa; R. Dähn; T. Huthwelker; E. Wieland
      Abstract: Publication date: Available online 18 March 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M. Vespa, R. Dähn, T. Huthwelker, E. Wieland


      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.03.006
       
  • Interaction processes at the concrete-bentonite interface after 13 years
           of FEBEX-Plug operation. Part I: Concrete alteration
    • Authors: María Cruz Alonso; José Luis García Calvo; Jaime Cuevas; María Jesús Turrero; Raúl Fernández; Elena Torres; Ana I. Ruiz
      Abstract: Publication date: Available online 14 March 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): María Cruz Alonso, José Luis García Calvo, Jaime Cuevas, María Jesús Turrero, Raúl Fernández, Elena Torres, Ana I. Ruiz
      This paper evaluates the modifications created in the concrete of the FEBEX shotcreted concrete plug after 13 years in the Grimsel Test Site conditions. During this time the concrete interacted with granite groundwater and also with bentonite porewater at the concrete/bentonite contact. Three long cores and 6 small cores from different parts of the concrete plug were evaluated. Mechanical performance was not modified during this time but hydraulic conductivity increased. The main transport mechanisms involved in the alteration of the concrete were groundwater flow from the host rock to the concrete and diffusion at the concrete/bentonite interface. Leaching occurred in the concrete parts near the host rock due to the action of granite water with further portlandite dissolution. The joint action of granite groundwater and bentonite porewater has caused many changes to the concrete matrix which was located at a depth lower than 5 cm from the bentonite-concrete interface. In the first centimetre C-S-H was significantly altered, incorporating elements like Al, S and Mg which change the initial microstructure by loss of compactness. The ettringite content was very high along the length of the concrete plug due to the shotcreting technique which made use of accelerator additives that caused the formation of ettringite. An increase in the ettringite content is also shown near the bentonite barrier. Therefore, sulphate diffused from the bentonite into the concrete, causing the massive formation of new ettringite. Chloride also diffused from the bentonite barrier deeper into the concrete by up to 4–5 cm from where the formation of Friedel's salt was detected.

      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.03.008
       
  • Effects of calcium leaching on diffusion properties of hardened and
           altered cement pastes
    • Authors: Kiyofumi Kurumisawa; Kazuko Haga; Daisuke Hayashi; Hitoshi Owada
      Abstract: Publication date: Available online 14 March 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Kiyofumi Kurumisawa, Kazuko Haga, Daisuke Hayashi, Hitoshi Owada
      It is very important to predict alterations in the concrete used for fabricating disposal containers for radioactive waste. Therefore, it is necessary to understand the alteration of cementitious materials caused by calcium leaching when they are in contact with ground water in the long term. To evaluate the long-term transport characteristics of cementitious materials, the microstructural behavior of these materials should be considered. However, many predictive models of transport characteristics focus on the pore structure, while only few such models consider both, the spatial distribution of calcium silicate hydrate (C-S-H), portlandite, and the pore spaces. This study focused on the spatial distribution of these cement phases. The auto-correlation function of each phase of cementitious materials was calculated from two-dimensional backscattered electron imaging, and the three-dimensional spatial image of the cementitious material was produced using these auto-correlation functions. An attempt was made to estimate the diffusion coefficient of chloride from the three-dimensional spatial image. The estimated diffusion coefficient of the altered sample from the three-dimensional spatial image was found to be comparable to the measured value. This demonstrated that it is possible to predict the diffusion coefficient of the altered cement paste by using the proposed model.

      PubDate: 2017-04-11T02:34:06Z
      DOI: 10.1016/j.pce.2017.03.007
       
  • Exploration of the causality between area changes of green spaces and
           waterlogging frequency in Beijing
    • Authors: Guofeng Wang; Jiancheng Chen; Chunhong Zhao; Xiaoxue Zhou; Xiangzheng Deng
      Abstract: Publication date: Available online 7 March 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Guofeng Wang, Jiancheng Chen, Chunhong Zhao, Xiaoxue Zhou, Xiangzheng Deng


      PubDate: 2017-03-08T21:16:13Z
      DOI: 10.1016/j.pce.2017.03.001
       
  • The study on ecological sustainable development in Chengdu
    • Authors: Yifan Li; Jinyan Zhan; Fan Zhang; Miaolin Zhang; Dongdong Chen
      Abstract: Publication date: Available online 6 March 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Yifan Li, Jinyan Zhan, Fan Zhang, Miaolin Zhang, Dongdong Chen
      Ecological footprint is one of the important methods to study ecological sustainable development, but ecological footprint focuses on only the static calculation of ecological sustainable development and cannot dynamically predict its development. In this study, we combine ecological footprint with system dynamics software STELLA to construct a predictable model of ecological sustainable development. We introduce rate1 and rate2 into the model, which reflects the change in per capita consumption of biological resources and energy due to the socio-economic development, and by changing the values of them to simulate a variety of scenarios. The results show that ecological sustainable development of Chengdu is in the state of ecological deficit, which is 1.43 million hm2 in 2013, and different rate1 and rate2 will lead to different changes in the ecological deficit. When rate1=rate2=0.1, the degree of ecological deficit in Chengdu is reduced from 1.43 million hm2 to 1.24 million hm2 in 2013-2018, and after 2018, it begins to increase, which will reach 1.32 million hm2 in 2021. And when rate1=rate2=0.05, the ecological deficit of Chengdu in 2013-2021 will decrease gradually, which from 1.43 million hm2 to 1.31 million hm2. These results reflect the impact of economic development on ecological sustainable development, and it can provide a reference for the balanced development of economic and ecological protection, which will help decision makers to do something for ecological sustainable development planning of Chengdu.

      PubDate: 2017-03-08T21:16:13Z
      DOI: 10.1016/j.pce.2017.03.002
       
  • Assessment of the content, structure, and source of soil dissolved organic
           matter in the coastal wetlands of Jiaozhou Bay, China
    • Authors: Min Xi; Yuanyuan Zi; Qinggai Wang; Sen Wang; Guolu Cui; Fanlong Kong
      Abstract: Publication date: Available online 6 March 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Min Xi, Yuanyuan Zi, Qinggai Wang, Sen Wang, Guolu Cui, Fanlong Kong
      The contents and structure of dissolved organic matter (DOM) in four typical wetlands, such as naked tidal, suaeda salsa, reed and spartina, were conducted to investigate the content, structure, and source of dissolved organic matter in coastal wetland soil. The soil samples were obtained from Jiaozhou Bay in January, April, July, and October of 2014. Results showed that the DOM contents in soil of four typical wetland were in order of spartina wetland > naked tidal > suaeda salsa wetland > reed wetland in horizontal direction, and decreased with the increase of soil depth on vertical section. In addition, the DOM contents changed with the seasons, in order of spring > summer > autumn > winter. The structural characteristics of DOM in Jiaozhou Bay wetland, such as aromaticity, hydrophobicity, molecular weight, polymerization degree of benzene ring carbon frame structure and so on were in order of spartina wetland > naked tidal > suaeda salsa wetland > reed wetland in the horizontal direction. On the vertical direction, they showed a decreasing trend with the increase of soil depth. The results of three dimensional fluorescence spectra and fluorescence spectrum parameters (FI, HIX, and BIX) indicated that the DOM in Jiaozhou Bay was mainly derived from the biological activities. The contents and structure of DOM had certain relevance, but the contents and source as well as the structure and source of DOM had no significant correlation. The external pollution including domestic sewage, industrial wastewater, and aquaculture sewage affected the correlation among the content, structure and source of DOM by influencing the percentage of non-fluorescent substance in DOM and disturbing the determination of protein-like fluorescence.

      PubDate: 2017-03-08T21:16:13Z
      DOI: 10.1016/j.pce.2017.03.004
       
  • Prediction of non-linear site response using downhole array data and
           numerical modeling: The Belleplaine (Guadeloupe) case study
    • Authors: Luis Fabian Bonilla; Philippe Guéguen; Fernando Lopez-Caballero; E. Diego Mercerat; Céline Gélis
      Abstract: Publication date: Available online 28 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Luis Fabian Bonilla, Philippe Guéguen, Fernando Lopez-Caballero, E. Diego Mercerat, Céline Gélis
      In this study, we analyze the acceleration time histories data at the Belleplaine (Guadeloupe, French West Indies) vertical array, recorded between 2008 and 2014, to evaluate the seismic response of sediments. First, we apply seismic interferometry by deconvolution method to compute the in-situ shear wave velocity between the sensor at the surface and the two shallow sensors located at GL-15m and GL-39m depth. The efficiency of this method is discussed by studying the variability of the velocity profile obtained and comparing with the in-situ geophysical survey of the site. Computed strains between sensors remain very weak, lower than 10-5, meaning that nonlinearities are not expected for these events. Moreover, the small dispersion of shear wave velocities values deduced from seismic interferometry may be related to the elastic behavior of the soil column. Furthermore, the transfer functions between each sensor combination are inverted to obtain a new velocity profile compatible with the geological knowledge of the site. The lag times calculated by seismic interferometry are then used to constrain random perturbations of the inverted velocity profile, allowing to study the variability of the 1D soil response. Since recorded motion has a PGA less than 10 cm/s2 in the dataset, we numerically predict the nonlinear response of the site using strong motion from a worldwide dataset. Furthermore, we study the ratio between the PGV and the medium shear velocity as a proxy showing the development of shear deformation during strong motion. Finally, using strong motion events from a worldwide dataset, we numerically predict the nonlinear response of the site based on shear wave velocity variation and the strain proxy computed by the particle velocity versus shear wave velocity ratio. We conclude that seismic interferometry by deconvolution is a robust and accurate solution to help extracting the shear wave velocity profile and to monitor the soil nonlinear response. This technique can be used when strong earthquakes will be recorded at this experimental site in order to track and assess nonlinear effects in the soil column.

      PubDate: 2017-03-01T21:11:12Z
      DOI: 10.1016/j.pce.2017.02.017
       
  • Green space water use and its impact on water resources in the capital
           region of China
    • Authors: Feng
      Abstract: Publication date: Available online 24 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Mi Feng


      PubDate: 2017-03-01T21:11:12Z
       
  • Remote sensing leaf water stress in coffee (Coffea arabica) using
           secondary effects of water absorption and random forests
    • Authors: Abel Chemura; Onisimo Mutanga; Timothy Dube
      Abstract: Publication date: Available online 23 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Abel Chemura, Onisimo Mutanga, Timothy Dube
      Water management is an important component in agriculture, particularly for perennial tree crops such as coffee. Proper detection and monitoring of water stress therefore plays an important role not only in mitigating the associated adverse impacts on crop growth and productivity but also in reducing expensive and environmentally unsustainable irrigation practices. Current methods for water stress detection in coffee production mainly involve monitoring plant physiological characteristics and soil conditions. In this study, we tested the ability of selected wavebands in the VIS/NIR range to predict plant water content (PWC) in coffee using the random forest algorithm. An experiment was set up such that coffee plants were exposed to different levels of water stress and reflectance and plant water content measured. In selecting appropriate parameters, cross-correlation identified 11 wavebands, reflectance difference identified 16 and reflectance sensitivity identified 22 variables related to PWC. Only three wavebands (485nm, 670nm and 885nm) were identified by at least two methods as significant. The selected wavebands were trained (n=36) and tested on independent data (n=24) after being integrated into the random forest algorithm to predict coffee PWC. The results showed that the reflectance sensitivity selected bands performed the best in water stress detection (r = 0.87, RMSE = 4.91% and pBias = 0.9%), when compared to reflectance difference (r = 0.79, RMSE = 6.19 and pBias=2.5%) and cross-correlation selected wavebands (r = 0.75, RMSE = 6.52 and pBias = 1.6). These results indicate that it is possible to reliably predict PWC using wavebands in the VIS/NIR range that correspond with many of the available multispectral scanners using random forests and further research at field and landscape scale is required to operationalize these findings.

      PubDate: 2017-03-01T21:11:12Z
      DOI: 10.1016/j.pce.2017.02.011
       
  • Evaluating the influence of the Red Edge band from RapidEye sensor in
           quantifying leaf area index for hydrological applications specifically
           focusing on plant canopy interception
    • Authors: Timothy Dube; Onisimo Mutanga; Mbulisi Sibanda; Cletah Shoko; Abel Chemura
      Abstract: Publication date: Available online 22 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Timothy Dube, Onisimo Mutanga, Mbulisi Sibanda, Cletah Shoko, Abel Chemura
      Reliable and accurate quantification of plant Leaf Area Index (LAI) is critical in understanding its role in reducing runoff. The main aim of the present study was to evaluate the ability of the Red Edge (RE) band derived from RapidEye in estimating LAI for applications in quantifying canopy interception at landscape scale. To achieve this objective, the study also compares the predictive power of two machine learning algorithms (Random Forest-RF and Stochastic Gradient Boosting-SGB) in estimating LAI. Comparatively, the results of the study have demonstrated that the inclusion of spectral information derived from the Red Edge band yields high accurate LAI estimates, when compared to the use of traditional traditional Red, Green, Blue and Near Infra-Red (traditional RGBNIR) spectral information. The results indicate that the use of the four traditional RGBNIR bands yielded comparatively lower R2 values and high Root Mean Squares, Mean Absolute Error (Pinus taeda: R2 of 0.60; the lowest RMSE (0.35 m2/m2) and MAE of 28); whereas the use of integration of traditional RGBNIR+RE in more accurate LAI estimates (Pinus taeda: R2 = 0.65; RMSE = 0.30 m2/m2) and the lowest MAE of 0.23). These findings therefore underscores the importance of new generation multispectral sensors with strategically-position bands and machine learning algorithms in estimating LAI for quantifying canopy interception, especially in resource-poor areas.

      PubDate: 2017-02-22T20:52:05Z
      DOI: 10.1016/j.pce.2017.02.016
       
  • Assessment of water availability for competing uses using SWAT and WEAP in
           South Phuthiatsana catchment, Lesotho
    • Authors: Motlatsi Maliehe; Deogratias M.M. Mulungu
      Abstract: Publication date: Available online 21 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Motlatsi Maliehe, Deogratias M.M. Mulungu
      The study assessed the quantity of surface water in the South Phuthiatsana catchment, estimated flows in ungauged catchments using Soil and Water Assessment Tool (SWAT) and allocated the resources in the catchment using Water Evaluation And Planning (WEAP) model. SWAT model was calibrated from 1979 to 2001, the p-factor was 65%, r_factor 0.58, NS 0.59 and R2 0.59 for calibration and for validation from 2002 to 2013, the p-factor was 57%, the r_factor was 1.34, the NS was 0.52, and R2 was 0.66. The results show the water balance as: 26% of precipitation form streamflow, 41% of the total flow comes from baseflow, while surface runoff accounts for 59%, 14% of precipitation percolates to shallow aquifer, 1% percolates to deep aquifer and 68% of precipitation is lost through evapotranspiration. The WEAP model was calibrated using CG024 and CG084 stations and historical demands. For CG024 calibration (1972 – 2002) NS was 0.72 and R2 was 0.84 and for validation (2003 – 2014) the NS was 0.73 and R2 was 0.74. For CG084 calibration (2007 – 2011) NS and R2 were 0.55 and 0.64 and for validation (2012 – 2014) the NS and R2 were 0.63 and 0.89 respectively. Two scenarios were evaluated. First for the reference scenario, the Metolong industrial demands of 1.46 Mm3 and environmental demands of 2.29 Mm3 were both not met. Secondly, for the irrigation expansion scenario, increasing irrigation land by 12.3%, a total of 4.44 Mm3 demands were not met (irrigation accounts for 65.65% of the unmet). Therefore, the study recommends an irrigation plan for the catchment. The irrigation plan has to include: irrigation systems designed for the site, meteorological stations and an irrigator’s association with experts forming part of the board.

      PubDate: 2017-02-22T20:52:05Z
      DOI: 10.1016/j.pce.2017.02.014
       
  • Zeolite formation in the presence of cement hydrates and albite
    • Authors: Barbara Lothenbach; Ellina Bernard; Urs Mäder
      Abstract: Publication date: Available online 21 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Barbara Lothenbach, Ellina Bernard, Urs Mäder
      Zeolite formation caused by interactions between cement hydrates and rock forming minerals was investigated by two sets of batch experiments and supported by thermodynamic modelling. The first set of batch experiments investigated the interaction between calcium silicate hydrates (C-S-H) (Ca0.8SiO2.8·32H2O) and ettringite (Ca6Al2(SO4)3(OH)12(H2O)26) as cement hydrate minerals and albite (NaAlSi3O8) as a rock forming mineral at 20, 50 and 80°C. The dissolution of C-S-H, ettringite and albite led to relatively high calcium and low silicon and sodium concentrations and to the formation of zeolite P(Ca) (Ca2Al2Si2O8·4.5H2O) and natrolite (Na2Al2Si3O10·2H2O). The second set of experiments used ettringite and silica fume as cement phases and NaAlO2 to represent a rock forming mineral. High initial sodium, hydroxide and aluminium concentrations were observed leading to the precipitation of zeolite X (Na2Al2Si2.5O9·6.2H2O) and C-S-H gel at 20 and 50°C where only 40 to 60% of the silica had reacted after 3 years. At 80°C where more silica fume had reacted, the formation of SiO2-rich zeolite Y (Na2Al2Si4O12·8H2O) and chabazite (CaAl2Si4O12·6H2O) was observed. Solubility products for the zeolite P(Ca), natrolite, chabazite, zeolite X and zeolite Y were obtained from the measured concentrations. Comparison with values published in the literature shows a high variability due to the flexibility of the Si to Al ratio in zeolite structures and underlines the need for systematic experimental determination of the solubility of different zeolites.

      PubDate: 2017-02-22T20:52:05Z
      DOI: 10.1016/j.pce.2017.02.006
       
  • Evaluation of Satellite and simulated rainfall products for hydrological
           applications in the Notwane Catchment, Botswana
    • Authors: P.K. Kenabatho; B.P. Parida; D.B. Moalafhi
      Abstract: Publication date: Available online 21 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): P.K. Kenabatho, B.P. Parida, D.B. Moalafhi
      In semi-arid catchments, hydrological modelling, water resources planning and management are hampered by insufficient spatial rainfall data which is usually derived from limited rain gauge networks. Satellite products are potential candidates to augment the limited spatial rainfall data in these areas. In this paper, the utility of the Tropical Rainfall Measuring Mission (TRMM) product (3B42 v7) is evaluated using data from the Notwane catchment in Botswana. In addition, rainfall simulations obtained from a multi-site stochastic rainfall model based on the generalised linear models (GLMs) were used as additional spatial rainfall estimates. These rainfall products were compared to the observed rainfall data obtained from six (6) rainfall stations available in the catchment for the period 1998-2012. The results show that in general the two approaches produce reasonable spatial rainfall estimates. However, the TRMM products provided better spatial rainfall estimates compared to the GLM rainfall outputs on an average, as more than 90% of the monthly rainfall variations were explained by the TRMM compared to 80% from the GLMs. However, there is still uncertainty associated mainly with limited rainfall stations, and the inability of the two products to capture unusually high rainfall values in the data sets. Despite this observation, rainfall indices computed to further assess the daily rainfall products (i.e. rainfall occurrence and amounts, length of dry spells) were adequately represented by the TRMM data compared to the GLMs. Performance from the GLMs is expected to improve with addition of further rainfall predictors. A combination of these rainfall products allows for reasonable spatial rainfall estimates and temporal (short term future) rainfall simulations from the TRMM and GLMs, respectively. The results have significant implications on water resources planning and management in the catchment which has, for the past three years, been experiencing prolonged droughts as shown by the drying of Gaborone dam (currently at a record low of 1.6% full), which is the main source of water supply to the city of Gaborone and neighbouring townships in Botswana.

      PubDate: 2017-02-22T20:52:05Z
      DOI: 10.1016/j.pce.2017.02.009
       
  • Evaluation of drought using SPEI drought class transitions and log-linear
           models for different agro-ecological regions of India
    • Authors: N.M. Alam; G.C. Sharma; Elsa Moreira; C. Jana; P.K. Mishra; N.K. Sharma; D. Mandal
      Abstract: Publication date: Available online 21 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): N.M. Alam, G.C. Sharma, Elsa Moreira, C. Jana, P.K. Mishra, N.K. Sharma, D. Mandal
      Markov chain and 3-dimensional log-linear models were attempted to model drought class transitions derived from the newly developed drought index the Standardized Precipitation Evapotranspiration Index (SPEI) at a 12 month time scale for six major drought prone areas of India. Log-linear modelling approach has been used to investigate differences relative to drought class transitions for last 48 years of standardized precipitation evapotranspiration index (SPEI) data sets were divided into two periods. In this study, the probabilities of drought class transition, the mean residence time, the 1, 2 or 3 months ahead prediction of average transition time between drought classes and the drought severity class have been derived. The seasonality of precipitation has been derived for non-homogeneous Markov chains which could be used to explain the effect of the potential retreat of drought. Quasi-association and Quasi-symmetry log-linear models have been fitted to the drought class transitions derived from SPEI-12 time series. The estimates of odds along with their confidence intervals were obtained to explain the progression of drought and estimation of drought class transition probabilities. For initial months as the drought severity increases the calculated odds shows lower value and the odds decreases for the succeeding months. This indicates that the ratio of expected frequencies of occurrence of transition to the non-drought class decreases as compared to transition to any drought class when the drought severity of the present class increases. From 3-dimensional log-linear model it is clear that during the last 24 years the drought probability has increased for almost all the six regions. The findings from the present study will immensely help to assess the impact of drought on the gross primary production and to develop future contingent planning in similar region worldwide.

      PubDate: 2017-02-22T20:52:05Z
      DOI: 10.1016/j.pce.2017.02.008
       
  • Modelling of cementitious backfill interactions with vitrified
           intermediate-level waste
    • Authors: Graham Baston; Timothy Heath; Fiona Hunter; Stephen Swanton
      Abstract: Publication date: Available online 21 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Graham Baston, Timothy Heath, Fiona Hunter, Stephen Swanton
      New types of wasteform are being considered for the geological disposal of radioactive intermediate-level waste (ILW) in the UK. These include vitrified ILW products arising from the application of thermal treatment processes. For disposal of such wasteforms in a geological disposal facility, a range of concepts are under consideration, including those with a high-pH cementitious backfill (the NRVB, Nirex Reference Vault Backfill). Alternatively, a cement-based material that buffers to a less alkaline pH could be used (an LPB, Low-pH Backfill). To assess the compatibility of these potential new wasteforms with cement-based disposal concepts, it is necessary to understand their impacts on the long-term evolution of the backfill. A scoping thermodynamic modelling study was undertaken to help understand the possible effects of these wasteforms on the performance of the backfill. The model primarily considers the interactions occurring between the vitirified waste, the porewater and the backfill, within a static and (in most cases) totally closed system. The approach was simplified by assuming equilibrium between the backfill and the corroded glass available at selected times, rather than involving detailed, reactive transport modelling. The aim was to provide an understanding of whether the impacts of the vitrified wastes on backfill performance are sufficient to compromise disposal in such environments. The calculations indicated that for NRVB, the overall alkaline buffering capacity of the backfill is not expected to be impaired by interactions with vitrified waste; rather the buffering will be to less alkaline pH values (above pH 9) but for a longer period. For the LPB, slightly lower pH values were predicted in some cases. The sorption capacities of the backfills are unlikely to be impaired by interactions with vitrified ILW. Indeed they may be increased, due to the additional C-S-H phase formation. The results of this study suggest that disposal of vitrified ILW in a cement-based disposal system with a high-pH backfill is a potentially viable disposal option.

      PubDate: 2017-02-22T20:52:05Z
      DOI: 10.1016/j.pce.2017.02.007
       
  • Evaluating the performance of the newly-launched Landsat 8 sensor in
           detecting and mapping the spatial configuration of water hyacinth
           (Eichhornia crassipes) in inland lakes, Zimbabwe
    • Authors: Timothy Dube; Onisimo Mutanga; Mbulisi Sibanda; Victor Bangamwabo; Cletah Shoko
      Abstract: Publication date: Available online 21 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Timothy Dube, Onisimo Mutanga, Mbulisi Sibanda, Victor Bangamwabo, Cletah Shoko
      The remote sensing of freshwater resources is increasingly becoming important, due to increased patterns of water use and the current or projected impacts of climate change and the rapid invasion by lethal water weeds. This study therefore sought to explore the potential of the recently-launched Landsat 8 OLI/TIRS sensor in mapping invasive species in inland lakes. Specifically, the study compares the performance of the newly-launched Landsat 8 sensor, with more advanced sensor design and image acquisition approach to the traditional Landsat-7 ETM+ in detecting and mapping the water hyacinth (Eichhornia crassipes) invasive species across Lake Chivero, in Zimbabwe. The analysis of variance test was used to identify windows of spectral separability between water hyacinth and other land cover types. The results showed that portions of the visible (B3), NIR (B4), as well as the shortwave bands (Band 8, 9 and 10) of both Landsat 8 OLI and Landsat 7 ETM, exhibited windows of separability between water hyacinth and other land cover types. It was also observed that on the use of Landsat 8 OLI produced high overall classification accuracy of 72 %, when compared Landsat 7 ETM, which yielded lower accuracy of 57 %. Water hyacinth had optimal accuracies (i.e. 92 %), when compared to other land cover types, based on Landsat 8 OLI data. However, when using Landsat 7 ETM data, classification accuracies of water hyacinth were relatively lower (i.e. 67%), when compared to other land cover types (i.e. water with accuracy of 100%). Spectral curves of the old, intermediate and the young water hyacinth in Lake Chivero based on: (a) Landsat 8 OLI, and (b) Landsat 7 ETM were derived. Overall, the findings of this study underscores the relevance of the new generation multispectral sensors in providing primary data-source required for mapping the spatial distribution, and even configuration of water weeds at lower or no cost over time and space.

      PubDate: 2017-02-22T20:52:05Z
      DOI: 10.1016/j.pce.2017.02.015
       
 
 
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