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  Subjects -> PHYSICS (Total: 793 journals)
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PHYSICS (572 journals)            First | 1 2 3 4 5 6 | Last

Nanotechnology Magazine, IEEE     Full-text available via subscription   (Followers: 23)
Natural Science     Open Access   (Followers: 9)
Nature Communications     Open Access   (Followers: 91)
Nature Materials     Full-text available via subscription   (Followers: 60)
Nature Physics     Full-text available via subscription   (Followers: 29)
NDT & E International     Hybrid Journal   (Followers: 25)
Neutron News     Hybrid Journal  
New Journal of Physics     Open Access   (Followers: 5)
Niels Bohr Collected Works     Full-text available via subscription  
Noise & Vibration Worldwide     Full-text available via subscription   (Followers: 5)
Noise Notes     Full-text available via subscription   (Followers: 3)
Nondestructive Testing And Evaluation     Hybrid Journal   (Followers: 11)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 3)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 9)
Nuclear Medicine and Biology     Hybrid Journal   (Followers: 2)
Open Journal of Biophysics     Open Access   (Followers: 1)
Open Journal of Fluid Dynamics     Open Access   (Followers: 5)
Open Journal of Microphysics     Open Access  
Open Physics     Open Access   (Followers: 2)
Optical Communications and Networking, IEEE/OSA Journal of     Hybrid Journal   (Followers: 7)
Optofluidics, Microfluidics and Nanofluidics     Open Access   (Followers: 1)
Organic Electronics     Hybrid Journal   (Followers: 5)
Organic Photonics and Photovoltaics     Open Access   (Followers: 2)
PAJ: A Journal of Performance and Art     Hybrid Journal   (Followers: 13)
Papers in Physics     Open Access  
Particle Physics Insights     Open Access   (Followers: 2)
Particuology     Hybrid Journal  
Pattern Recognition in Physics     Open Access   (Followers: 2)
Pergamon Materials Series     Full-text available via subscription  
Phase Transitions and Critical Phenomena     Full-text available via subscription   (Followers: 1)
Philosophical Magazine     Hybrid Journal   (Followers: 2)
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences     Full-text available via subscription   (Followers: 6)
Philosophy and Foundations of Physics     Full-text available via subscription  
Physica B: Condensed Matter     Hybrid Journal   (Followers: 5)
physica status solidi (a)     Hybrid Journal   (Followers: 1)
physica status solidi (b)     Hybrid Journal   (Followers: 1)
physica status solidi (c)     Hybrid Journal   (Followers: 1)
Physica Status Solidi - Rapid Research Letters     Hybrid Journal   (Followers: 1)
Physicae Organum : Revista dos Estudantes de Física da Universidade de Brasília     Open Access  
Physical Communication     Hybrid Journal   (Followers: 2)
Physical Review C     Full-text available via subscription   (Followers: 20)
Physical Review Special Topics - Physics Education Research     Open Access   (Followers: 6)
Physical Review X     Open Access   (Followers: 9)
Physical Sciences Data     Full-text available via subscription   (Followers: 1)
Physics - spotlighting exceptional research     Full-text available via subscription   (Followers: 1)
Physics and Chemistry of Glasses - European Journal of Glass Science and Technology Part B     Full-text available via subscription   (Followers: 3)
Physics and Chemistry of Liquids: An International Journal     Hybrid Journal   (Followers: 1)
Physics and Chemistry of the Earth, Parts A/B/C     Hybrid Journal   (Followers: 2)
Physics and Materials Chemistry     Open Access   (Followers: 1)
Physics Essays     Full-text available via subscription   (Followers: 1)
Physics in Medicine & Biology     Full-text available via subscription   (Followers: 11)
Physics in Perspective     Hybrid Journal   (Followers: 1)
Physics International     Open Access   (Followers: 2)
Physics Letters A     Hybrid Journal   (Followers: 11)
Physics Letters B     Open Access   (Followers: 3)
Physics of Fluids     Hybrid Journal   (Followers: 30)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Plasmas     Hybrid Journal   (Followers: 7)
Physics of the Dark Universe     Open Access   (Followers: 1)
Physics of the Solid State     Hybrid Journal   (Followers: 2)
Physics of Wave Phenomena     Hybrid Journal   (Followers: 1)
Physics Procedia     Partially Free   (Followers: 1)
Physics Reports     Full-text available via subscription   (Followers: 2)
Physics Research International     Open Access   (Followers: 1)
Physics Today     Hybrid Journal   (Followers: 38)
Physics World     Full-text available via subscription   (Followers: 3)
Physics-Uspekhi     Full-text available via subscription  
Physik in unserer Zeit     Hybrid Journal   (Followers: 1)
Physik Journal     Hybrid Journal  
Plasma Physics and Controlled Fusion     Hybrid Journal   (Followers: 2)
Plasma Physics Reports     Hybrid Journal   (Followers: 1)
Pramana     Open Access   (Followers: 10)
Preview     Hybrid Journal  
Proceedings of the National Academy of Sciences     Full-text available via subscription   (Followers: 478)
Proceedings of the National Academy of Sciences, India Section A     Hybrid Journal   (Followers: 3)
Progress in Materials Science     Hybrid Journal   (Followers: 23)
Progress in Planning     Hybrid Journal  
Progress of Theoretical and Experimental Physics     Open Access  
Quantum Electronics     Full-text available via subscription   (Followers: 3)
Quantum Measurements and Quantum Metrology     Open Access  
Quantum Studies : Mathematics and Foundations     Hybrid Journal   (Followers: 2)
Quarterly Journal of Mechanics and Applied Mathematics     Hybrid Journal   (Followers: 3)
Radiation Effects and Defects in Solids     Hybrid Journal   (Followers: 1)
Radiation Measurements     Hybrid Journal   (Followers: 2)
Radiation Physics and Chemistry     Hybrid Journal   (Followers: 1)
Radiation Protection Dosimetry     Hybrid Journal   (Followers: 2)
Radiation Research     Full-text available via subscription   (Followers: 3)
Radio Science     Full-text available via subscription   (Followers: 4)
Radiological Physics and Technology     Hybrid Journal   (Followers: 2)
Reflets de la physique     Full-text available via subscription  
Reports on Mathematical Physics     Full-text available via subscription  
Reports on Progress in Physics     Full-text available via subscription   (Followers: 2)
Research & Reviews : Journal of Physics     Full-text available via subscription  
Research in Drama Education     Hybrid Journal   (Followers: 12)
Research Journal of Physics     Open Access  
Results in Physics     Open Access   (Followers: 1)
Reviews in Mathematical Physics     Hybrid Journal  
Reviews of Accelerator Science and Technology     Hybrid Journal  
Reviews of Geophysics     Full-text available via subscription   (Followers: 20)

  First | 1 2 3 4 5 6 | Last

Journal Cover Physics and Chemistry of the Earth, Parts A/B/C
  [SJR: 0.624]   [H-I: 42]   [2 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1474-7065
   Published by Elsevier Homepage  [2801 journals]
  • Moment tensors, state of stress and their relation to faulting processes
           in Gujarat, Western India
    • Abstract: Publication date: Available online 3 February 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Sandeep Kumar Aggarwal, Prosanta Kumar Khan, Sarada Prasad Mohanty, Zafeiria Roumelioti
      Time domain moment tensor analysis of 145 earthquakes (Mw 3.2 to 5.1), occurring during the period 2006-2014 in Gujarat region, has been performed. The events are mainly confined in the Kachchh area demarcated by the Island belt and Kachchh Mainland faults to its north and south, and two transverse faults to its east and west. Libraries of Green’s functions were established using the 1D velocity model of Kachchh, Saurashtra and Mainland Gujarat. Green’s functions and broadband displacement waveforms filtered at low frequency (0.5 - 0.8 Hz) were inverted to determine the moment tensor solutions. The estimated solutions were rigorously tested through number of iterations at different source depths for finding reliable source locations. The identified heterogeneous nature of the stress fields in the Kachchh area allowed us to divide this into four Zones 1-4. The stress inversion results indicate that the Zone 1 is dominated with radial compression, Zone 2 with strike-slip compression, and Zones 3 and 4 with strike-slip extensions. The analysis further shows that the epicentral region of 2001 MW 7.7 Bhuj mainshock, located at the junction of Zones 2, 3 and 4, was associated with predominant compressional stress and strike-slip motion along ∼NNE-SSW striking fault on the western margin of the Wagad uplift. Other tectonically active parts of Gujarat (e.g. Jamnagar, Talala and Mainland) show earthquake activities are dominantly associated with strike-slip extension/compression faulting. Stress inversion analysis shows that the maximum compressive stress axes (σ1) are vertical for both the Jamnagar and Talala regions and horizontal for the Mainland Gujarat. These stress regimes are distinctly different from those of the Kachchh region.


      PubDate: 2016-02-10T12:08:43Z
       
  • Analysis of the 2012–2013 Torreperogil-Sabiote seismic swarm
    • Abstract: Publication date: Available online 3 February 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M. Hamdache, J.A. Peláez, J. Henares, Y. Damerdji, R. Sawires
      This study analyses the temporal clustering, spatial clustering, and statistics of the 2012–2013 Torreperogil-Sabiote (southern Spain) seismic swarm. During the swarm, more than 2200 events were located, mostly at depths of 2–5 km, with magnitude event up to m bLg 3.9 (M w 3.7). On the basis of daily activity rate, three main temporal phases are identified and analysed. The analysis combines different seismological relationships to improve our understanding of the physical processes related to the swarm’s occurrence. Each temporal phase is characterized by its cumulative seismic moment. Using several different approaches, we estimate a catalog completeness magnitude of m c ≅ 1.5. The maximum likelihood b-value estimates for each swarm phase are 1.11 ± 0.09, 1.04 ± 0.04, and 0.90 ± 0.04, respectively. To test the hypothesis that a b-value decrease is a precursor to a large event, we study temporal variations in b-value using overlapping moving windows. A relationship can be inferred between change in b-value and the regime style of the rupture. b-values are indicators of the stress regime, and influence the size of ruptures. The fractal dimension D 2 is used to perform spatial analysis. Cumulative gamma and beta functions are used to analyse the behaviour of inter-event distances during the earthquake sequence.


      PubDate: 2016-02-10T12:08:43Z
       
  • On the relationship between atmospheric water vapour transport and
           extra-tropical cyclones development
    • Abstract: Publication date: Available online 3 February 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Juan A. Ferreira, Margarida L.R. Liberato, Alexandre M. Ramos
      In this study we seek to investigate the role of atmospheric water vapour on the intensification of extra-tropical cyclones over the North Atlantic Ocean and more specifically to investigate the linkage between atmospheric rivers’ conditions leading to the explosive development of extra-tropical cyclones. Several WRF-ARW simulations for three recent extra-tropical storms that had major negative socio-economic impacts in the Iberian Peninsula and south-western Europe (Klaus, 2009; Gong, 2013 and Stephanie, 2014) are performed in which the water vapour content of the initial and boundary conditions are tuned. Analyses of the vertically integrated vapour transport show the dependence of the storms’ development with atmospheric water vapour. In addition, results also show changes in the shape of the jet stream resulting in a reduction of the upper wind divergence, which in turn affects the intensification of the extra-tropical cyclones studied. This study suggests that atmospheric rivers tend to favour the conditions for explosive extra-tropical storms’ development in the three case studies, as simulations performed without the existence of atmospheric rivers produce shallow mid-latitudes cyclones, that is, cyclones that are not so intense as those on the reference simulations.


      PubDate: 2016-02-10T12:08:43Z
       
  • Seismic Moment Tensor Inversion Using 3D Velocity Model and Its
           Application to the 2013 Lushan Earthquake Sequence
    • Abstract: Publication date: Available online 4 February 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Lupei Zhu, Xiaofeng Zhou
      Source inversion of small-magnitude events such as aftershocks or mine collapses requires use of relatively high frequency seismic waveforms which are strongly affected by small-scale heterogeneities in the crust. In this study, we developed a new inversion method called gCAP3D for determining general moment tensor of a seismic source using Green’s functions of 3D models. It inherits the advantageous features of the “Cut-and-Paste” (CAP) method to break a full seismogram into the Pnl and surface-wave segments and to allow time shift between observed and predicted waveforms. It uses grid search for 5 source parameters (relative strengths of the isotropic and compensated-linear-vector-dipole components and the strike, dip, and rake of the double-couple component) that minimize the waveform misfit. The scalar moment is estimated using the ratio of L 2 norms of the data and synthetics. Focal depth can also be determined by repeating the inversion at different depths. We applied gCAP3D to the 2013 M s 7.0 Lushan earthquake and its aftershocks using a 3D crustal-upper mantle velocity model derived from ambient noise tomography in the region. We first relocated the events using the double-difference method. We then used the finite-differences method and reciprocity principle to calculate Green’s functions of the 3D model for 20 permanent broadband seismic stations within 200 km from the source region. We obtained moment tensors of the mainshock and 74 aftershocks ranging from M w 5.2 to 3.4. The results show that the Lushan earthquake is a reverse faulting at a depth of 13–15 km on a plane dipping 40–47∘ to N46∘ W. Most of the aftershocks occurred off the main rupture plane and have similar focal mechanisms to the mainshock’s, except in the proximity of the mainshock where the aftershocks’ focal mechanisms display some variations.


      PubDate: 2016-02-10T12:08:43Z
       
  • Degradation of organic matter from wastewater using advanced primary
           treatment by O3 and O3/UV in a pilot plant
    • Abstract: Publication date: Available online 23 January 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Yaneth Bustos-Terrones, Jesús Gabriel Rangel-Peraza, Antonio Sanhouse, Erick R. Bandala, Luis G. Torres
      The oxidation of organic matter from wastewater using ozone, ultraviolet radiation and ozone/UV oxidation was evaluated in a pilot plant, applying a continuous effluent arising from the Autonomous Metropolitan University wastewater treatment plant. The oxidation was measured as the efficiency to remove organic load, measured as chemical oxygen demand. The use of ozone and UV was evaluated separately and in combination through a continuous process. Three different ozone doses (0.6 to 1.2 mg O3/L) and three different UV radiation fluencies (6.7 to 20.12 mJ/cm2) were assessed. A synergistic effect of the combined process ozone/UV was demonstrated, and a maximal chemical oxygen demand reduction was achieved both processes. Due to residence times used (less than 1 min), 36% of chemical oxygen demand reduction was obtained when ozone treatment was evaluate separately and only 9% using ultraviolet radiation.


      PubDate: 2016-01-25T11:18:14Z
       
  • Estimation of Groundwater Vulnerability to Pollution based on DRASTIC in
           the Niipele sub-Basin of the Cuvelai Etosha Basin, Namibia
    • Abstract: Publication date: Available online 23 January 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J.T. Hamutoko, H. Wanke, H.J. Voigt
      Surface water is a scarce resource in Namibia with about sixty percent of Namibia’s population dependent on groundwater for drinking purposes. With increasing population, the country faces water challenges and thus groundwater resources need to be managed properly. One important aspect of Integrated Water Resources Management is the protection of water resources, including protection of groundwater from contamination and over-exploitation. This study explores vulnerability mapping as a basic tool for protecting groundwater resources from pollution. It estimates groundwater vulnerability to pollution in the upper Niipele sub-basin of the Cuvelai-Etosha in Northern Namibia using the DRASTIC index. The DRASTIC index uses GIS to estimate groundwater vulnerability by overlaying different spatially referenced hydrogeological parameters that affect groundwater contamination. The study assesses the discontinuous perched aquifer (KDP) and the Ohangwena multi-layered aquifer 1 (KOH-1). For perched aquifers, point data was regionalized by a hydrotope approach whereas for KOH-1 aquifer, inverse distance weighting was used. The hydrotope approach categorized different parts of the hydrogeological system with similar properties into five hydrotopes. The result suggests that the discontinuous perched aquifers are more vulnerable than Ohangwena multi-layered aquifer 1. This implies that vulnerability increases with decreasing depth to water table because contaminants have short travel time to reach the aquifer when they are introduced on land surface. The nitrate concentration ranges between 2 to 288 mg/l in perched aquifers while in Ohangwena multi-layered aquifer 1, it ranges between 1 to 133 mg/l. It was observed that perched aquifers have high nitrate concentrations than Ohangwena 1 aquifer, which correlates well with the vulnerability results.


      PubDate: 2016-01-25T11:18:14Z
       
  • Knowledge and Practices regarding Water, Sanitation and Hygiene (WASH)
           among mothers of under-fives in Mawabeni rural area, Zimbabwe
    • Abstract: Publication date: Available online 9 January 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Tendai Demberere, Tayedza Chidziya, Tatenda Ncozana, Norman Manyeruke
      The research study sought to assess knowledge and practices of mothers of under-fives regarding WASH in Mawabeni communal area in Zimbabwe. Focus group discussions, interviews, questionnaires and observation checklists were used to collect data. Data was analysed by developing specific themes related to the objectives and then frequencies were computed in Microsoft Excel. The mean score on WASH knowledge for the mothers of under-fives according to the Knowledge Index was 1. Knowledge regarding safety of water from different sources was generally poor with 70% of the mothers regarding water from surface sources to be safe to drink without treatment. Use of wide mouthed containers without lids was also common in the study area. However, no relationship was established between the type of water container used and the socio-demographic characteristics of the respondents. Knowledge regarding the importance of ablutions was generally good as highlighted by 78% of the mothers who regarded latrines as being important in prevention and control of diseases as well as for hygiene purposes. However, latrine ownership was noted to be related to the income level of the household (p < 0.0001). A total of 57% of the mothers had good knowledge on hand washing, indicating that it helped to prevent diseases. Generally, knowledge levels and sanitation practices on WASH among mothers of under-fives in Mawabeni were both poor and this could be a contributory factor to the high incidence of diarrheal diseases for under-fives in the area.


      PubDate: 2016-01-12T10:18:40Z
       
  • Recent trends of extreme temperature indices for the Iberian Peninsula
    • Abstract: Publication date: Available online 30 December 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): D. Fonseca, M.J. Carvalho, M. Marta-Almeida, P. Melo-Gonçalves, A. Rocha
      Climate change and extreme climate events have a significant impact on societies and ecosystems. As a result, climate change projections, especially related with extreme temperature events, have gained increasing importance due to their impacts on the well-being of the population and ecosystems. However, most studies in the field are based on coarse global climate models (GCMs). In this study, we perform a high resolution downscaling simulation to evaluate recent trends of extreme temperature indices. The model used was Weather Research and Forecast (WRF) forced by MPI-ESM-LR, which has been shown to be one of the more robust models to simulate European climate. The domain used in the simulations includes the Iberian Peninsula and the simulation covers the 1986 − 2005 period (i.e. recent past). In order to study extreme temperature events, trends were computed using the Theil-Sen method for a set of temperature indexes defined by the Expert Team on Climate Change Detection and Indices (ETCCDI). For this, daily values of minimum and maximum temperatures were used. The trends of the indexes were computed for annual and seasonal values and the Mann-Kendall Trend test was used to evaluate their statistical significance. In order to validate the results, a second simulation, in which WRF was forced by ERA-Interim, was performed. The results suggest an increase in the number of warm days and warm nights, especially during summer and negative trends for cold nights and cold days for the summer and spring. For the winter, contrary to the expected, the results suggest an increase in cold days and cold nights (warming hiatus). This behavior is supported by the WRF simulation forced by ERA-Interim for the autumn days, pointing to an extension of the warming hiatus phenomenon to the remaining seasons. These results should be used with caution since the period used to calculate the trends may not be long enough for this purpose. However, the general sign of trends are similar for both simulations despite some differences in their magnitudes.


      PubDate: 2015-12-31T11:29:33Z
       
  • Land use mapping from CBERS-2 images with open source tools by applying
           different classification algorithms
    • Abstract: Publication date: Available online 29 December 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Antonio J. Sanhouse-Garcia, Jesús Gabriel Rangel-Peraza, Yaneth Bustos-Terrones, Alfonso García-Ferrer, Francisco J. Mesas-Carrascosa
      Land cover classification is often based on different characteristics between their classes, but with great homogeneity within each one of them. This cover is obtained through field work or by mean of processing satellite images. Field work involves high costs; therefore, digital image processing techniques have become an important alternative to perform this task. However, in some developing countries and particularly in Casacoima municipality in Venezuela, there is a lack of geographic information systems due to the lack of updated information and high costs in software license acquisition. This research proposes a low cost methodology to develop thematic mapping of local land use and types of coverage in areas with scarce resources. Thematic mapping was developed from CBERS-2 images and spatial information available on the network using open source tools. The supervised classification method per pixel and per region was applied using different classification algorithms and comparing them among themselves. Classification method per pixel was based on Maxver algorithms (maximum likelihood) and Euclidean distance (minimum distance), while per region classification was based on the Bhattacharya algorithm. Satisfactory results were obtained from per region classification, where overall reliability of 83.93 % and kappa index of 0.81 % were observed. Maxver algorithm showed a reliability value of 73.36% and kappa index 0.69%, while Euclidean distance obtained values of 67.17% and 0.61% for reliability and kappa index, respectively. It was demonstrated that the proposed methodology was very useful in cartographic processing and updating, which in turn serve as a support to develop management plans and land management. Hence, open source tools showed to be an economically viable alternative not only for forestry organizations, but for the general public, allowing them to develop projects in economically depressed and/or environmentally threatened areas.


      PubDate: 2015-12-31T11:29:33Z
       
  • Influence of Deposition of Fine Plant Debris in River Floodplain Shrubs on
           Flood Flow Conditions - the Warta River Case Study
    • Abstract: Publication date: Available online 21 December 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Robert Mazur, Tomasz Kałuża, Joanna Chmist, Natalia Walczak, Ireneusz Laks, Paweł Strzeliński
      This paper presents problems caused by organic material transported by flowing water. This material is usually referred to as plant debris or organic debris. Its composition depends on the characteristic of the watercourse. For lowland rivers, the share of the so-called small organic matter in plant debris is considerable. This includes both various parts of water plants and floodplain vegetation (leaves, stems, blades of grass, twigs, etc.). During floods, larger woody debris poses a significant risk to bridges or other water engineering structures. It may cause river jams and may lead to damming of the flowing water. This, in turn, affects flood safety and increases flood risk in river valleys, both directly and indirectly. The importance of fine plant debris for the phenomenon being studied comes down to the hydrodynamic aspect (plant elements carried by water end up on trees and shrubs, increase hydraulic flow resistance and contribute to the nature of flow through vegetated areas changed from micro-to macro-structural). The key part of the research problem under analysis was to determine qualitative and quantitative debris parameters and to establish the relationship between the type of debris and the type of land use of river valleys (crop fields, meadows and forested river sections). Another problem was to identify parameters of plant debris for various flow conditions (e.g. for low, medium and flood flows). The research also included an analysis of the materials deposited on the structure of shrubs under flood flow conditions during the 2010 flood on the Warta River.


      PubDate: 2015-12-23T11:00:19Z
       
  • State of Tectonic Stress in Shillong Plateau of Northeast India
    • Abstract: Publication date: Available online 23 December 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Santanu Baruah, Saurabh Baruah, Sowrav Saikia, Mahesh N. Shrivastava, Antara Sharma, C.D. Reddy, J.R. Kayal
      Tectonic stress regime in the Shillong plateau, northeast region of India, is examined by stress tensor inversion. Some 97 reliable fault plane solutions are used for stress inversion by the Michael and Gauss methods. Although an overall NNW-SSE compressional stress is observed in the area, the stress regime varies from western part to eastern part of the plateau. The eastern part of the plateau is dominated by NNE-SSW compression and the western part by NNW-SSE compression. The NNW-SSE compression in the western part may be due to the tectonic loading induced by the Himalayan orogeny in the north, and the NNE-SSW compression in the eastern part may be attributed to the influence of oblique convergence of the Indian plate beneath the Indo-Burma ranges. Further, Gravitational Potential Energy (GPE) derived stress also indicates a variation from west to east.


      PubDate: 2015-12-23T11:00:19Z
       
  • QLg tomography in Gujarat, Western India
    • Abstract: Publication date: Available online 23 December 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Sandeep Kumar Aggarwal, Prosanta Kumar Khan
      We propose a novel Lg attenuation tomography model (QLg tomography) for the state of Gujarat, Western India, using earthquake data recorded by the Gujarat Seismic Network, operated by the Institute of Seismological Research in Gandhinagar. The waveform dataset consist of 400 3-component recordings, produced by 60 earthquakes with magnitude (ML) spanning from 3.6 to 5.1, recorded at 60 seismic stations having epicentral distances spanning between 200 and 500 km. Spectral amplitude decays for Lg wave displacement were obtained by generalized inversion at 17 frequencies spanning between 0.9 and 9 Hz. Lg wave propagation efficiency was measured by Lg/Pn spectral ratio categorizing as efficient ratio ≥ 6 for 86%, intermediate ratio of 3 to 6 for 10% and inefficient ratio < 3 for 4% paths of total 400 ray paths. The earthquake size and quality of waveform recorded at dense network found sufficient to resolve lateral variation of QLg in Gujarat. Average power-law attenuation relationship obtained for Gujarat as QLg(f) = 234f0.64, which corresponds to high attenuation in comparison to peninsular India shield region and other several regions around the world. QLg tomography resolves the highly attenuating crust of extremely fractured Saurashtra region and tectonically active Kachchh region. The Gujarat average attenuation is also lying in between them. The low attenuation in Cambay and Narmada rift basins and extremely low attenuation in patch of Surendranagar area is identified. This study is the first attempt and can be utilized as pivotal criteria for scenario hazard assessment, as maximum hazard has been reported in highly attenuating tectonically active Kachchh region and in low attenuating Cambay, Narmada and Surendranagar regions. The site and source terms are also obtained along with the QLg inversion. The estimated site responses are comparable with observed local geological condition and agree with the previously reported site amplifications at the same sites. The source terms are comparable with local magnitude estimated from Network. The Mw (Lg) is nearly equivalent to ML (GSN) and the slight differences are noted for larger magnitude events.


      PubDate: 2015-12-23T11:00:19Z
       
  • Nanosized iron based permeable reactive barriers for nitrate removal
           – Systematic review
    • Abstract: Publication date: Available online 15 December 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Rui Araújo, Ana C. Meira Castro, João Santos Baptista, António Fiúza
      It is unquestionable that an effective decision concerning the usage of a certain environmental clean-up technology should be conveniently supported. Significant amount of scientific work focusing on the reduction of nitrate concentration in drinking water by both metallic iron and nanomaterials and their usage in permeable reactive barriers has been worldwide published over the last two decades. This work aims to present in a systematic review of the most relevant research done on the removal of nitrate from groundwater using nanosized iron based permeable reactive barriers. The research was based on scientific papers published between 2004 and June 2014. It was performed using 16 combinations of keywords in 34 databases, according to PRISMA statement guidelines. Independent reviewers validated the selection criteria. From the 4161 records filtered, 45 met the selection criteria and were selected to be included in in this review. This study’s outcomes show that the permeable reactive barriers are, indeed, a suitable technology for denitrification and with good performance record but the long-term impact of the use of nanosized zero valent iron in this remediation process, in both on the environment and on the human health, is far to be conveniently known. As a consequence, further work is required on this matter, so that nanosized iron based permeable reactive barriers for the removal of nitrate from drinking water can be genuinely considered an eco-efficient technology.


      PubDate: 2015-12-19T10:10:01Z
       
  • An exploratory study of spatial annual maximum of monthly precipitation in
           the northern region of Portugal
    • Abstract: Publication date: Available online 15 December 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): D.P. Gomes, M.M. Neves, E. Moreira
      Adequately analyzing and modeling the extreme rainfall events is of great importance because of the effects that their magnitude and frequency can have on human life, agricultural productivity and economic aspects, among others. A single extreme event may affect several locations, and their spatial dependence has to be appropriately taken into account. Classical geostatistics is a well-developed field for dealing with location referenced data, but it is largely based on Gaussian processes and distributions, that are not appropriate for extremes. In this paper, an exploratory study of the annual maximum of monthly precipitation recorded in the northern area of Portugal from 1941-2006 at 32 locations is performed. The aim of this paper is to apply max-stable processes, a natural extension of multivariate extremes to the spatial set-up, to briefly describe the models considered and to estimate the required parameters to simulate prediction maps.


      PubDate: 2015-12-15T09:57:35Z
       
  • Temperature and heat wave trends in northwest Mexico
    • Abstract: Publication date: Available online 26 July 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Polioptro F. Martínez-Austria, Erick R. Bandala, Carlos Patiño-Gómez
      Increase in temperature extremes is one of the main expected impacts of climate change, as well as one of the first signs of its occurrence. Nevertheless, results emerging from General Circulation Models, while sufficient for large scales, are not enough for forecasting local trends and, hence, the IPCC has called for local studies based on on-site data. Indeed, it is expected that climate extremes will be detected much earlier than changes in climate averages. Heat waves are among the most important and least studied climate extremes, however its occurrence has been only barely studied and even its very definition remains controversial. This paper discusses the observed changes in temperature trends and heat waves in Northwestern Mexico, one of the most vulnerable regions of the country. The climate records in two locations of the region are analyzed, including one of the cities with extreme climate in Mexico, Mexicali City in the state of Baja California and the Yaqui River basin at Sonora State using three different methodologies. Results showed clear trends on temperature increase and occurrence of heat waves in both of the study zones using the three methodologies proposed. As result, some policy making suggestion are included in order to increase the adaptability of the studied regions to climate change, particularly related with heat wave occurrence.


      PubDate: 2015-12-11T09:49:44Z
       
  • Regionalization of precipitation for the Iberian Peninsula and climate
           change
    • Abstract: Publication date: Available online 26 July 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A.C. Parracho, P. Melo-Gonçalves, A. Rocha
      Temporal variability of precipitation over the Iberian Peninsula (IP) has high spatial gradients. Therefore, statistics of the temporal behaviour of precipitation and derived quantities over the IP must be estimated taking into account these spatial gradients. Some statistics can be displayed over a map. However there are statistics, such as Probability Density Functions at each location of the IP, that are impossible to display in a map. Because of this, it is mandatory to reduce the number of degrees of freedom which, in this case, consists of a reduction of the time series representative of the IP domain. In this work, we present a spatial partition of the IP region into areas of similar precipitation. For that, an observed dataset of daily-total precipitation for the years between 1951 and 2003 was used. The land-only high resolution data was obtained on a regular grid with 0.2° resolution in the IP domain. This data was subjected to a K-means Cluster Analysis in order to divide the IP into K regions. The clustering was performed using the squared Euclidean distance. Four clusters of IP grid points, defining 4 IP regions, were identified. The grid points in each region share the same time-varying behaviour which is different from region to region. The annual precipitation discriminates the following regions: (i) northwest Iberia, (ii) north Iberia, (iii) a large region ranging from the centre to the western and southwestern shores of the Iberia, and (iv) another large region extending from the centre to the Mediterranean shores of the IP. The regions obtained for the four seasons of the year are similar. These results are consistent with the thermodynamic characteristics described in the available literature. These Iberian regions were used to assess climate change of seasonal precipitation from the multi-model ensemble of the fifteen simulations provided by the European project ENSEMBLES. Probability Density Functions of seasonal-total precipitation averaged in each region were estimated for a reference climate (1961–1960), a near-future climate (2021–2050), and a distant-future climate (2069–2098). Climate change projections are based on comparisons of these functions between each future climate and the reference climate. Finally we emphasize that: (i) the methodology used here, based on Cluster Analysis, can be used to regionalize other areas of the world, and (ii) the identified regions of the IP can be used to represent the Iberian precipitation by four time series that can be subjected to further analysis, and whose results can be presented in a concise manner.


      PubDate: 2015-12-11T09:49:44Z
       
  • WRF-chem sensitivity to vertical resolution during a saharan dust event
    • Abstract: Publication date: Available online 8 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J.C. Teixeira, A.C. Carvalho, Paolo Tuccella, Gabriele Curci, A. Rocha
      The Saharan dust event that occurred between the 22nd and 30th of June 2012 influenced the atmospheric radiative properties over North Africa, the Iberian Peninsula, the Western Mediterranean basin, extending its effects to France and Southern England. This event is well documented in satellite imagery, as well as on the air quality stations over the Iberian Peninsula and the AERONET NASA network. In order to assess the effect of the model vertical resolution on the extinction coefficient fields, as a proxy to the particulate matter concentrations in the atmosphere, the WRF-Chem model was applied during this period over a mother domain with a resolution of 18km, covering Europe and North Africa. To this end five model setups differing in the number of vertical levels were tested. Model skills were evaluated by comparing the model results with CALIPSO and EARLINET LIDAR data. Results show that the model is able to simulate the higher level aerosol transport but it is susceptible to the vertical resolution used. This is due to the thickness of the transport layers which is, eventually, thinner than the vertical resolution of the model. When comparing model results to the observed vertical profiles, it becomes evident that the broad features of the extinction coefficient profile are generally reproduced in all model configurations, but finer details are captured only by the higher resolution simulations.


      PubDate: 2015-12-11T09:49:44Z
       
  • Seasonal drought predictability in Portugal using
           statistical–dynamical techniques
    • Abstract: Publication date: Available online 16 May 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A.F.S. Ribeiro, C.A.L. Pires
      Atmospheric forecasting and predictability are important to promote adaption and mitigation measures in order to minimize drought impacts. This study estimates hybrid (statistical–dynamical) long-range forecasts of the regional drought index SPI (3-months) over homogeneous regions from mainland Portugal, based on forecasts from the UKMO operational forecasting system, with lead-times up to 6months. ERA-Interim reanalysis data is used for the purpose of building a set of SPI predictors integrating recent past information prior to the forecast launching. Then, the advantage of combining predictors with both dynamical and statistical background in the prediction of drought conditions at different lags is evaluated. A two-step hybridization procedure is performed, in which both forecasted and observed 500hPa geopotential height fields are subjected to a PCA in order to use forecasted PCs and persistent PCs as predictors. A second hybridization step consists on a statistical/hybrid downscaling to the regional SPI, based on regression techniques, after the pre-selection of the statistically significant predictors. The SPI forecasts and the added value of combining dynamical and statistical methods are evaluated in cross-validation mode, using the R 2 and binary event scores. Results are obtained for the four seasons and it was found that winter is the most predictable season, and that most of the predictive power is on the large-scale fields from past observations. The hybridization improves the downscaling based on the forecasted PCs, since they provide complementary information (though modest) beyond that of persistent PCs. These findings provide clues about the predictability of the SPI, particularly in Portugal, and may contribute to the predictability of crops yields and to some guidance on users (such as farmers) decision making process.


      PubDate: 2015-12-11T09:49:44Z
       
  • A dependence modelling study of extreme rainfall in Madeira Island
    • Abstract: Publication date: Available online 2 December 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Délia Gouveia-Reis, Luiz Guerreiro Lopes, Sandra Mendonça
      The dependence between variables plays a central role in multivariate extremes. In this paper, spatial dependence of Madeira Island’s rainfall data is addressed within an extreme value copula approach through an analysis of maximum annual data. The impact of altitude, slope orientation, distance between rain gauge stations and distance from the stations to the sea are investigated for two different periods of time. The results obtained highlight the influence of the island’s complex topography on the spatial distribution of extreme rainfall in Madeira Island.


      PubDate: 2015-12-06T09:04:17Z
       
  • Identification of nitrate sources in groundwater and potential impact on
           drinking water reservoir (Goczałkowice reservoir, Poland)
    • Abstract: Publication date: Available online 30 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Joanna Czekaj, Sabina Jakóbczyk – Karpierz, Hanna Rubin, Sławomir Sitek, Andrzej J. Witkowski
      Goczałkowice dammed reservoir (area - 26 km2) is a strategic object for flood control in the Upper Vistula River catchment and one of the most important source of drinking water in the Upper Silesian Industrial Region (Southern Poland). Main aims of the investigation were identification of sources of nitrate and assessment of their significance in potential risk to groundwater quality. In the catchment area monitoring network of 22 piezometers, included 14 nested, have been installed. The significant spatial and seasonal differences in chemical composition between northern and southern part of the catchment were indicated based on the groundwater sampling conducted twice - in autumn 2011 and spring 2012. Maximum observed concentrations of nitrate were identified in northern part of the study area 255 mg/L as a results of inappropriate sewage management and agriculture activity. Results, based on the combines multi-scale hydrogeological and hydrochemical field studies, groundwater flow and transport modelling, dual stable isotope approach and geochemical modelling indicate mainly agriculture and inappropriate sewage water management as a sources of NO3 - contamination of groundwater which moreover is affected by geochemical processes. In general, contaminated groundwater does not impact surface water quality. However, due to high concentration of nitrate in northern part a continues measurements of nitrogen compounds should be continued and used for reducing uncertainty of the predictive scenarios of the mass transport modelling in the study area.


      PubDate: 2015-12-01T18:42:23Z
       
  • Water quality monitoring in the Paul do Boquilobo Biosphere Reserve
    • Abstract: Publication date: Available online 30 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): C. Baptista, L. Santos
      The Paul do Boquilobo is an important wetland ecosystem classified by Unesco as a MAB Biosphere reserve also awarded Ramsar site status, representing one of the most important habitats for the resident nesting colony of Cattle Egret (Bulbucus ibis). Yet owing to its location, it suffers from human induced impacts which include industrial and domestic effluent discharges as well as agricultural land use which have negatively impacted water quality. The current study reports the results obtained from the introductory monitoring programme of surface water quality in the Nature Reserve to emphasize the detrimental impact of the anthropogenic activities in the water quality of such an important ecosystem. The study involved physicochemical and biotic variables, microbial parameters and biological indicators. Results after 3 years of monitoring bring to evidence a poor water quality further impaired by seasonal patterns. Statistical analysis of data attributed water quality variation to 3 main parameters - pH, dissolved oxygen and nitrates, indicating heavy contamination loads from both organic and agricultural sources. Seasonality plays a role in water flow and climatic conditions, where sampling sites presented variable water quality data, suggesting a depurative function of the wetland.


      PubDate: 2015-12-01T18:42:23Z
       
  • Timescale Differences between SC-PDSI and SPEI for Drought Monitoring in
           China
    • Abstract: Publication date: Available online 19 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Haiyan Zhao, Ge Gao, Wei An, Xukai Zou, Haitao Li, Meiting Hou
      The Palmer Drought Severity Index (PDSI) has been widely used to monitor drought. Its characteristics are more suitable for measuring droughts of longer timescales, and this fact has not received much attention. The Standardized Precipitation Evapotranspiration Index (SPEI) can better reflect the climatic water balance, owing to its combination of precipitation and potential evapotranspiration. In this study, we selected monthly average air temperature and precipitation data from 589 meteorological stations of China's National Meteorological Information Center, to compare the effects of applying a self-calibrating PDSI (SC-PDSI) and SPEI to monitor drought events in the station regions, with a special focus on differences of event timescale. The results show the following. 1) Comparative analysis using SC-PDSI and SPEI for drought years and characters of three dry periods from 1961–2011 in the Beijing region showed that durations of SC-PDSI-based dry spells were longer than those of 3-month and 6-month SPEIs, but equal to those of 12-month or longer timescale SPEIs. 2) For monitoring evolution of the fall 2009 to spring 2010 Southwest China drought and spring 2000 Huang-Huai drought, 3-month SPEI could better monitor the initiation, aggravation, alleviation and relief of drought in the two regions, whereas the SC-PDSI was insensitive to drought recovery because of its long-term memory of previous climate conditions. 3) Analysis of the relationship between SC-PDSI for different regions and SPEI for different timescales showed that correlation of the two indexes changed with region, and SC-PDSI was maximally correlated with SPEI of 9–19 months in China. Therefore, SC-PDSI is only suitable for monitoring mid- and long-term droughts, owing to the strong lagged autocorrelation such as 0.4786 for 12-month lagged ones in Beijing, whereas SPEI is suitable for both short- and long-term drought-monitoring and should have greater application prospects in China.


      PubDate: 2015-11-22T17:42:46Z
       
  • Assessment of the effectiveness of combined adsorption and photocatalysis
           for removal of the herbicide isoproturon
    • Abstract: Publication date: Available online 14 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Martín M. Dávila-Jiménez, María P. Elizalde-González, Esmeralda García-Díaz, Alba M. Santes-Aquino
      The aim of this research was to decompose isoproturon and adsorb its photoproducts by developing a carbon material from a juice industry waste. Carbon-TiO2 hybrid materials were obtained by impregnating carbonized guava seeds with TiO2 gels prepared from TiOSO4⋅xH2O and NH4OH using glycerol as a binder and thermally treating the materials at 500°C. Raman studies confirmed the anatase phase of TiO2. SEM images showed isolated TiO2 agglomerates firmly attached to the carbon surface. The adsorption behavior of isoproturon on guava carbon was studied and yielded S-type adsorption isotherms. The photocatalytic activities of the prepared hybrid materials were monitored to study the kinetics and elimination process both of the herbicide and its photoproducts. The reaction was monitored by UV–Vis spectrophotometry, LC-DAD and LC-MS, enabling identification of some intermediate species. Among the photoproducts produced by carbon-TiO2 hybrid materials, amino-isopropylphenol was detected.
      Graphical abstract image

      PubDate: 2015-11-18T17:26:06Z
       
  • Hydraulic design to optimize the treatment capacity of Multi-Stage
           filtration units
    • Abstract: Publication date: Available online 10 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): C.N. Mushila, G.M.M. Ochieng, F.A.O. Otieno, S.M. Shitote, C.W. Sitters
      Multi-Stage Filtration (MSF) can provide a robust treatment alternative for surface water sources of variable water quality in rural communities at low operation and maintenance costs. MSF is a combination of Slow Sand Filters (SSFs) and Pre-treatment systems. The general objective of this research was to optimize the treatment capacity of MSF. A pilot plant study was undertaken to meet this objective. The pilot plant was monitored for a continuous 98 days from commissioning till the end of the project. Three main stages of MSF namely: The Dynamic Gravel Filter (DGF), Horizontal-flow Roughing Filter (HRF) and SSF were identified, designed and built. The response of the respective MSF units in removal of selected parameters guiding drinking water quality such as microbiological (Faecal and Total coliform), Suspended Solids, Turbidity, PH, Temperature, Iron and Manganese was investigated. The benchmark was the Kenya Bureau (KEBS) and World Health Organization (WHO) Standards for drinking water quality. With respect to microbiological raw water quality improvement, MSF units achieved on average 98% Faecal and 96% Total coliform removal. Results obtained indicate that implementation of MSF in rural communities has the potential to increase access to portable water to the rural populace with a probable consequent decrease in waterborne diseases. With a reduced down time due to illness, more time would be spent in undertaking other economic activities.


      PubDate: 2015-11-14T17:09:46Z
       
  • Cloning and expression of vgb gene in Bacillus cereus, improve phenol and
           p-nitrophenol biodegradation
    • Abstract: Publication date: Available online 11 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Angel Eduardo Vélez-Lee, Felipe Cordova-Lozano, Erick R. Bandala, Jose Luis Sanchez-Salas
      In this work, the vgb gene from Vitrocilla stercoraria was used to genetically modify a Bacillus cereus strain isolated from pulp and paper wastewater effluent. The gene was cloned in a multicopy plasmid (pUB110) or uni-copy gene using a chromosome integrative vector (pTrpBG1). B. cereus and its recombinant strains were used for phenol and p-nitrophenol biodegradation using aerobic or micro-aerobic conditions and two different temperatures (i.e. 37 and 25°C). Complete (100%) phenol degradation was obtained for the strain where the multicopy of vgb gene was present, 98% for the strain where uni-copy gene was present and 45% for wild type strain for the same experimental conditions (i.e. 37°C and aerobic condition). For p-nitrophenol degradation at the same conditions, the strain with the multi-copy vgb gene was capable to achieve 50% of biodegradation, ∼100% biodegradation was obtained using the uni-copy strain and ∼24% for wild type strain. When the micro-aerobic condition were tested, the biodegradation yield showed a significant decreased. The biodegradation trend observed for aerobic was similar for micro-aerobic assessments: the modified strains showed higher degradation rates when compared with wild type strain. For all experimental conditions, the highest p-nitrophenol degradation was observed using the strain with uni-copy of vgb gene. Besides the increase of biodegradative capability of the strain, insertion of the vgb gene was observed able to modify other morphological characteristics such as avoiding the typical flake formation in the B. cereus culture. In both cases, the modification seems to be related with the enhancement of oxygen supply to the cells generated by the vgb gene insertion. The application of the genetically modified microorganism (GMM) to the biodegradation of pollutants in contaminated water possess high potential as an environmentally friendly technology to facing this emergent problem.


      PubDate: 2015-11-14T17:09:46Z
       
  • Dry spells assessment with reference to the maize crop in the Luvuvhu
           River catchment of South Africa
    • Abstract: Publication date: Available online 11 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Teboho Elisa Masupha, Mokhele Edmond Moeletsi, Mitsuru Tsubo
      Agricultural productivity in South Africa is negatively affected by drought as a result of frequent periodic dry spells and increasing crop water demands resulting in poor crop development and low yields. Thus, we embarked on this study which aims at investigating dry spell occurrences in relation to growing season of maize in the Luvuvhu River Catchment. Daily rainfall data (1945-2014) from 12 stations which represent the catchment fairly well was utilized in this study. Three consecutive planting dates were staggered based on three consecutive onsets of the rainy season. Dry spells were categorized into three groups: short, medium and long dry spells. The data was then subjected to theoretical distribution fitting using the Anderson-Darling goodness-of-fit test; and probabilities of occurrence were computed using a probabilistic model that best fits the data. Trend analysis was performed on the frequency of dry spells per growing period using the non-parametric Spearman’s rank correlation test. Out results indicated high probabilities (≥80%) of short dry spells at all the stations irrespective of the timing of planting. Further analysis revealed that a risk of yield reduction with planting following the first onset of rains was higher than that with planting following the second and third onsets. In order to minimize this risk, farmers can be advised to plant between mid-November to mid-December. Trend analysis indicated no trend for all the various dry spell lengths except for Thohoyandou with a decreasing trend and Sigonde with a weak increasing trend in long dry spells. Such findings can be used to describe drought conditions for improvement of agricultural productivity and food security, in a given area.


      PubDate: 2015-11-14T17:09:46Z
       
  • Joint Venture Schemes in Limpopo Province and their outcomes on
           smallholder farmers Livelihoods
    • Abstract: Publication date: Available online 11 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Everisto Mapedza, Barbara van Koppen, Pinimidzai Sithole, Magalie Bourblanc
      Joint Venture schemes based on the floppy irrigation technology are being promoted in the post-Apartheid South Africa’s Limpopo Province. Access to land and water resources in South Africa are largely viewed as a mechanism for re-dressing the Apartheid injustices. This research was part of a broader applied research to help inform irrigation practise in the Limpopo Province. The research used literature review, key informant interviews and a questionnaire survey. The overall research question sought to understand how the Joint Venture Schemes had benefited the smallholder farmers. This paper argues that the joint venture partnership created a new injustice. Firstly, the Joint Venture Scheme design is fundamentally a bad idea which disempower farmers not only to water access but also land as well. The choice of the 'efficient' floppy irrigation technology was made by the state and entailed that land had to be managed as a single unit. In order to make more effective use of this highly sophisticated new technology, the smallholder farmers also needed to go into a joint venture partnership with a white commercial farmer. By virtue of signing the Joint Venture agreement the farmers were also forfeiting their land and water rights to be used for crop production. The smallholder farmers lost access to their water and land resources and were largely relegated to sharing profits – when they exist - with hardly any skills development despite what was initially envisaged in the Joint Venture partnership. Secondly, the implementation of the JVS has been skewed from the start which explains the bad results. This paper further shows how the negative outcomes affected women in particular. As the smallholder farmers argue the technological options chosen by the state have excluded both male and female farmers from accessing and utilising their land and water resources in order to improve their livelihoods; it has entrenched the role of the state and the private interests at the expense of the smallholder male and female farmers in whose name the irrigation funding was justified. The paper concludes by offering recommendations on how joint venture schemes can be genuinely participatory and meaningfully address the rural livelihoods.


      PubDate: 2015-11-14T17:09:46Z
       
  • Oil refinery wastewater treatment using coupled electrocoagulation and
           fixed film biological processes
    • Abstract: Publication date: Available online 11 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Laura S. Pérez, Oscar M. Rodriguez, Silvia Reyna, José Luis Sánchez-Salas, J. Daniel Lozada, Marco A. Quiroz, Erick R. Bandala
      Oil refinery wastewater was treated using a coupled treatment process including electrocoagulation (EC) and a fixed film aerobic bioreactor. Different variables were tested to identify the best conditions using this procedure. After EC, the effluent was treated in an aerobic biofilter. EC was capable to remove over 88% of the overall chemical oxygen demand (COD) in the wastewater under the best working conditions (6.5 V, 0.1 M NaCl, 4 electrodes without initial pH adjustment) with total petroleum hydrocarbon (TPH) removal slightly higher than 80%. Aluminum release from the electrodes to the wastewater was found an important factor for the EC efficiency and closely related with several operational factors. Application of EC allowed to increase the biodegradability of the sample from 0.015, rated as non-biodegradable, up to 0.5 widely considered as biodegradable. The effluent was further treated using an aerobic biofilter inoculated with a bacterial consortium including gram positive and gram negative strains and tested for COD and TPH removal from the EC treated effluent during 30 days. Cell count showed the typical bacteria growth starting at day three and increasing up to a maximum after eight days. After day eight, cell growth showed a plateau which agreed with the highest decrease on contaminant concentration. Final TPHs concentration was found about 600 mgL-1 after 30 days whereas COD concentration after biological treatment was as low as 933 mgL-1. The coupled EC-aerobic biofilter was capable to remove up to 98% of the total TPH amount and over 95% of the COD load in the oil refinery wastewater.


      PubDate: 2015-11-14T17:09:46Z
       
  • SPI drought class prediction using log-linear models applied to wet and
           dry seasons
    • Abstract: Publication date: Available online 11 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Elsa E. Moreira
      A log-linear modelling for 3-dimensional contingency tables was used with categorical time series of SPI drought class transitions for prediction of monthly drought severity. Standardized Precipitation Index (SPI) time series in 12- and 6-month time scales were computed for 10 precipitation time series relative to GPCC datasets with 2.5 degrees spatial resolution located over Portugal and with 112 years length (1902 to 2014). The aim was modelling two-month step class transitions for the wet and dry seasons of the year and then obtain probability ratios – Odds – as well as their respective confidence intervals to estimate how probable a transition is compared to another. The prediction results produced by the modelling applied to wet and dry season separately, for the 6- and the 12-month SPI time scale, were compared with the results produced by the same modelling without the split, using skill scores computed for the entire time series length. Results point to good prediction performances ranging from 70-80% in the percentage of corrects (PC) and 50-70% in the Heidke skill score (HSS), with the highest scores obtained when the modelling is applied to the SPI12. The adding up of the wet and dry seasons introduced in the modelling brought improvements in the predictions, of about 0.9-4% in the PC and 1.3-6.8% in the HSS, being the highest improvements obtained in the SPI6 application.


      PubDate: 2015-11-14T17:09:46Z
       
  • Ground and surface water quality along a dambo transect in Chihota
           smallholder farming area, Marondera district, Zimbabwe
    • Abstract: Publication date: Available online 12 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M. Wuta, G. Nyamadzawo, J. Mlambo, P. Nyamugafata
      In many smallholder farms in sub-Saharan Africa dambos are used for grazing and crop production especially horticultural crops. Increased use of dambos especially for crop production can result in ground and surface water pollution. Ground and surface water quality along a dambo transect in Chihota, Zimbabwe, was investigated between October 2013 and February 2014. The transect was divided into; upland (control), dambo gardens (mid-slope) and the river (valley bottom). Water samples for quality assessment were collected in October 2013 (peak of dry season) and February 2014 (peak of rainy season). The collected water samples were analysed for pH, faecal coliforms, total nitrogen, electrical conductivity, total dissolved solids (TDS), and some selected nutrients (P, K, Ca, Mg, Na, Zn, and Cu). Water pH was 7.0, 6.4 and 6.1 for river water, garden and upland wells respectively. During the wet season total nitrogen (TN) concentrations were 233 mg/L for uplands, 242 mg/L for gardens and 141 mg/L for the river. During the dry season, TN concentrations were all below 20 mg/L, and were not significantly different among sampling stations along the dambo transect. Dry season faecal coliform units (fcu) were significantly different and were 37.2, 30.0 and 5.0 for upland wells, garden wells and river respectively. Wet season faecal coliforms were also significantly different and were 428.5, 258.0 and 479.4 fcu for upland wells, garden wells and river respectively. The other measured physico-chemical parameters also varied with sampling position along the transect. It was concluded that TN and fcu in sampled water varied with season and that wet season concentrations were significantly higher than dry season concentrations. High concentrations of faecal coliforms and total N during the wet season was attributed to increased water movement. Water from upland wells, garden wells and river was not suitable for human consumption according to WHO standards during both dry and wet season.


      PubDate: 2015-11-14T17:09:46Z
       
  • Rural food insecurity and poverty mappings and their linkage with water
           resources in the Limpopo River Basin
    • Abstract: Publication date: Available online 10 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.S. Magombeyi, A.E. Taigbenu, J. Barron
      The mappings of poverty and food insecurity were carried out for the rural districts of the four riparian countries (Botswana, Mozambique, South Africa and Zimbabwe) of the Limpopo river basin using the results of national surveys that were conducted between 2003 and 2013. The analysis shows lower range of food insecure persons (0 – 40%) than poverty stricken persons (0 – 95%) that is attributable to enhanced government and non-government food safety networks in the basin countries, the dynamic and transitory nature of food insecurity which depends on the timings of the surveys in relation to harvests, markets and food prices, and the limited dimension of food insecurity in relation to poverty which tends to be a more structural and pervasive socio-economic condition. The usefulness of this study in influencing policies and strategies targeted at alleviating poverty and improving rural livelihoods lies with using food insecurity mappings to address short-term socio-economic conditions and poverty mappings to address more structural and long-term deprivations. Using the poverty line of $1.25/day per person (2008–2013) in the basin, Zimbabwe had the highest percentage of 68.7% of its rural population classified as poor, followed by Mozambique with 68.2%, South Africa with 56.1% and Botswana with 20%. While average poverty reduction of 6.4% was observed between 2003 and 2009 in Botswana, its population growth of 20.1% indicated no real poverty reduction. Similar observations are made about Mozambique and Zimbabwe where population growth outstripped poverty reductions. In contrast, both average poverty levels and population increased by 4.3% and 11%, respectively, in South Africa from 2007–2010. While areas of high food insecurity and poverty consistently coincide with low water availability, it does not indicate a simple cause-effect relationship between water, poverty and food insecurity. With limited water resources, rural folks in the basin require stronger institutions, increased investments and support to enable them generate sufficient income from their rain-fed farming livelihood to break out of the poverty cycle.


      PubDate: 2015-11-14T17:09:46Z
       
  • Anthropogenic pressures on productive soils in Corlu and Cerkezkoy
    • Abstract: Publication date: Available online 10 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Ezgi Tok
      Unplanned land use is mainly arising from previous regional (local) planning policies based on economic growth, which resulted in the misuse of the land. The fertile lands are converted to industrial/urban areas along with forest areas converted to agricultural zones which directly affect the flora and fauna in a negative way. This study aims to identify the land use transformations by using Remote Sensing and GIS due to prior socio-economic return focused politics resulting in environmental degradations. Additionally, this paper presents an analysis of the transformation of fertile lands into industrial/urban zones with respect to Land Capability Classes. The study area is one of the most urbanized and industrialized zones in Turkey. The reason behind this transformation lies solely in the fact that the aforementioned area is quite appealing to industrialization due to its easy access to infrastructure and its compliance with the spatial requirements. Up until now the development plans of the region have been prepared with a socioeconomic agenda promoting the economic growth while disregarding the ecological and environmental balance, which unfortunately boosted the large-scale degradation of the environment. Although the focus area is within a zone suitable for industrialization, this region also takes place within a wide river basin (Ergene River Basin) making it an ideal location for highly productive crop cultivation (LUC Classes 1 to 4), which is a rare commodity in long term.


      PubDate: 2015-11-14T17:09:46Z
       
  • Electrokinetic treatment of polluted soil at pilot level coupled to an
           advanced oxidation process of its wastewater
    • Abstract: Publication date: Available online 6 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): B. Ochoa, L. Ramos, A. Garibay, M. Pérez - Corona, M.C. Cuevas, J. Cárdenas, M. Teutli, E. Bustos
      Soil contaminated with hydrocarbons is a current problem of great importance. These contaminants may be toxic, can retain water and block gas exchange with the atmosphere, which produces a poor-quality soil unsuitable for ecological health. Electroremediation is among the treatments for the removal of such contaminants. In this research, a pilot-level electroremediation test was applied using a circular arrangement of electrodes with a Ti cathode at the middle of the cell surrounded by six IrO2 - Ta2O5 Ti anodes. The presence of an NaOH electrolyte helps to develop the electromigration and electro-osmosis of gasoline molecules (at 1 126 mg Kg-1) surrounded by Na+ ions. The hydrocarbons are directed towards the cathode and subsequently removed in an aqueous Na+ - hydrocarbon solution, and the -OH migrates to the anode. During electrokinetic treatment, the physicochemical characteristics of the soil close to either the cathode or anode and at the half-cell were evaluated during the three weeks of treatment. During that time, more than 80% of hydrocarbons were removed. Hydrocarbons removed by the electrokinetic treatment of gasoline-polluted soil were collected in a central wastewater compartment and subsequently treated with a Fenton-type advanced oxidation process. This achieved more than 70% mineralization of the hydrocarbons to CO2 and H2O within 1.5h; its low toxicity status was verified using the Deltatox® kit test. With this approach, the residual water complied with the permissible limits of COD, pH, and electrical conductivity for being discharged into water bodies, according to Mexican norm NOM-001-SEMARNAT-1996.
      Graphical abstract image

      PubDate: 2015-11-09T16:57:08Z
       
  • Determination of the water quality index ratings of water in the
           Mpumalanga and North West Provinces, South Africa
    • Abstract: Publication date: Available online 2 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Elijah M.M. Wanda, Bhekie B. Mamba, Titus A.M. Msagati
      This study reports on the water quality index (WQI) of wastewater and drinking water in the Mpumalanga and North West provinces of South Africa. The WQI is one of the most effective tools available to water sustainability researchers, because it provides an easily intelligible ranking of water quality on a rating scale from 0 to 100, based on the ascription of different weightings to several different parameters. In this study the WQI index ratings of wastewater and drinking water samples were computed according to the levels of pH, electrical conductivity (EC), biochemical oxygen demand (BOD), E.coli, temperature, turbidity and nutrients (nitrogen and phosphates) found in water samples collected from the two provinces between June and December, 2014. This study isolated three groups of WQ-rated waters, namely: fair (with a WQI range = 32.87–38.54%), medium (with a WQI range = 56.54–69.77%) and good (with a WQI range= 71.69–81.63%). More specifically, 23%, 23% and 54% of the sampled sites registered waters with fair, medium and good WQ ratings respectively. None of the sites sampled during the entire period of the project registered excellent or very good water quality ratings, which would ordinarily indicate that no treatment is required to make it fit for human consumption. Nevertheless, the results obtained by the Eerstehoek and Schoemansville water treatment plants in Mpumalanga and North West provinces, respectively, suggest that substantial improvement in the quality of water samples is possible, since the WQI values for all of the treated samples were higher than those for raw water. Presence of high levels of BOD, low levels of dissolved oxygen (DO), E.coli, nitrates and phosphates especially in raw water samples greatly affected their overall WQ ratings. It is recommended that a point-of-use system should be introduced to treat water intended for domestic purposes in the clean-water-deprived areas.


      PubDate: 2015-11-06T16:28:16Z
       
  • Comparative assessment of water treatment using polymeric and inorganic
           coagulants
    • Abstract: Publication date: Available online 5 November 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): I.K.M. Manda, R.C.G. Chidya, J.D.K. Saka, T. Biswick
      Portable water plays a vital role in improving human life, particularly in controlling the spread of diseases. However, problems associated with lack of potable water are still common especially in developing countries including Malawi. Until now little information exists on the effectiveness of available commercial coagulants used by national water boards in Malawi. Therefore, this study was undertaken in Southern Region Water Board (SRWB) to investigate the efficiency of polymeric coagulants (sufdfloc 3850 and algaefloc 19s) in turbidity reduction comparative with inorganic coagulant (aluminium sulphate) at Zomba, Liwonde, Mangochi, Chikwawa and Mulanje Treatment plants. The jar test method was used to determine the effectiveness of the water coagulants. The results revealed that sudfloc 3850 was most effective in reducing turbidity at Mangochi (99.4±0.06 %) and Liwonde (97.2±0.04 %) using 0.4 mg L-1flocculant dose. The Zomba, Mulanje and Chikwawa plants gave 19.56±0.03%, 29.23±0.02% and 9.43±0.02% total reductions respectively. Algaefloc 19s afforded the highest turbidity reduction at Liwonde and Mangochi plants (98.66±0.06 and 97.48±0.05 % at a dose of 0.4 and 0.6 mg L-1 respectively), while Chikwawa provided the lowest (9.52±0.01%). At the Zomba and Mulanje plants 20.5±0.03% and 28.4±0.04% reductions were obtained respectively. The inorganic flocculant, alum provided a 99.0±0.05 % and 98.6±0.04 % reduction at a dose of 4.0 mg L-1 and 6.0 mg L-1 at Zomba and Liwonde plants respectively. The lowest reductions in turbidity were achieved at Chikwawa (7.50±0.01%), Mangochi (12.97±0.02%) and Mulanje (25.00±0.02). The best and optimum pH ranges for polymeric and inorganic coagulants were 7.20 to 7.80 and 7.35 to 7.57 respectively. The results further revealed that sudfloc 3850 and algaefloc 19s achieved faster formation of heavy flocs than alum. At 0.4 mg L-1flocculant dosage sudfloc 3850 and algaefloc 19s required ten times lower dosages than alum. Therefore, the polymeric coagulants could be used instead of alum, the choice dependant on the type of water.


      PubDate: 2015-11-06T16:28:16Z
       
  • Assessment of impact of climate change and adaptation strategies on maize
           production in Uganda
    • Abstract: Publication date: Available online 30 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Duncan A. Kikoyo, Joel Nobert
      Globally, various climatic studies have estimated a reduction of crop yields due to changes in surface temperature and precipitation especially for the developing countries which is heavily dependent on agriculture and lacks resources to counter the negative effects of climate change. Uganda’s economy and the wellbeing of its populace depend on rain-fed agriculture which is susceptible to climate change. This study quantified the impacts of climate change and variability in Uganda and how coping strategies can enhance crop production against climate change and/or variability. The study used statistical methods to establish various climate change and variability indicators across the country, and uses the FAO AquaCrop model to simulate yields under possible future climate scenarios with and without adaptation strategies. Maize, the most widely grown crop was used for the study. Meteorological, soil and crop data were collected for various districts representing the maize growing ecological zones in the country. Based on this study, it was found that temperatures have increased by up to 1°C across much of Uganda since the 1970s, with rates of warming around 0.3°C per decade across the country. High altitude, low rainfall regions experience the highest level of warming, with over 0.5oC/decade recorded in Kasese. Rainfall is variable and does not follow a specific significant increasing or decreasing trend. For both future climate scenarios, Maize yields will reduce in excess of 4.7% for the fast warming-low rainfall climates but increase on average by 3.5% for slow warming-high rainfall regions, by 2050. Improved soil fertility can improve yields by over 50% while mulching and use of surface water management practices improve yields by single digit percentages. The use of fertilizer application needs to go hand in hand with other water management strategies since more yields as a result of the improved soil fertility leads to increased water stress, especially for the dry climates.


      PubDate: 2015-11-02T13:39:32Z
       
  • Superoleophillic electrospun POLYSTRENE/exofoliated graphite fibre for
           selective removal of crude oil from water
    • Abstract: Publication date: Available online 30 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): S.Oluwagbemiga Alayande, Enock O. Dare, F.O. Grace Olorundare, D. Nkosi, Titus A.M. Msagati, B.B. Mamba
      During oil spills, the aquatic environment is greatly endangered because oil floats on water making the penetration of sunlight difficult therefore primary productivity is compromised, birds and aquatic organisms are totally eliminated within a short period. It is therefore essential to remove the oil from the water bodies after the spillage. This work reports on the fabrication of oil loving electrospun polystyrene-exofoliated graphite fibre with hydrophobic and oleophillic surface properties. The fibre was applied for the selective adsorption of crude oil from simulated crude oil spillage on water. The maximum oil adsorption capacity of the EPS/EG was 1.15 kg/g in 20 minutes while the lowest oil adsorption capacity was 0.81 kg/g in 10 minutes. Cheap oil adsorbent was developed with superoleophillic and superhydrophobic properties.


      PubDate: 2015-11-02T13:39:32Z
       
  • Determination of the health of Lunyangwa wetland using Wetland
           Classification and Risk Assessment Index
    • Abstract: Publication date: Available online 31 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Elijah M.M. Wanda, Golden Msilimba
      Wetlands are major sources of various ecological goods and services including storage and distribution of water in space and time which help in ensuring the availability of surface and groundwater throughout the year. However, there still remains a poor understanding of the range of values of water quality parameters that occur in wetlands either in its impacted state or under natural conditions. It was thus imperative to determine the health of Lunyangwa wetland in Mzuzu City in Malawi in order to classify and determine its state. This study used the Escom’s Wetland Classification and Risk Assessment Index Field Guide to determine the overall characteristics of Lunyangwa wetland and to calculate its combined Wetland Index Score. Data on site information, field measurements (i.e EC, pH, temperature and DO) and physical characteristics of Lunyangwa wetland were collected from March, 2013 to February, 2014. Results indicate that Lunyangwa wetland is a largely open water zone which is dominated by free-floating plants on the water surface, beneath surface and emergent in substrate. Furthermore, the wetland can be classified as of a C ecological category (score = 60-80%), which has been moderately modified with moderate risks of the losses and changes occurring in the natural habitat and biota in the wetland. It was observed that the moderate modification and risk were largely because of industrial, agricultural, urban/social catchment stressors on the wetland. This study recommends an integrated and sustainable management approach coupled with continuous monitoring and evaluation of the health of the wetland for all stakeholders in Mzuzu City. This would help to maintain the health of Lunyangwa wetland which is currently at risk of being further modified due to the identified catchment stressors.


      PubDate: 2015-11-02T13:39:32Z
       
  • Impact of urbanization on the ecology of Mukuvisi River, Harare, Zimbabwe
    • Abstract: Publication date: Available online 31 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): N.A.G. Moyo, M.M. Rapatsa
      The main objective in this study was to compare the physico-chemical characteristics and biota of a river (Mukuvisi) passing through an urban area to that of a non-urbanised river (Gwebi). Five sites in the Mukuvisi River and five sites in the Gwebi River were sampled for water physico-chemical parameters (pH, conductivity, DO, BOD, TDS, ammonia, Cl, SO4 2-, PO4 2-, NO3 3-, F-, Pb, Cu, Fe, Mn, Zn and Cr) once every month between August, 2012 - August, 2013. Cluster analysis based on the physico-chemical parameters grouped the sites into two groups. Mukuvisi River sites formed their own grouping except for one site which was grouped with Gwebi River sites. Principal Component Analysis (PCA) was used to extract the physico-chemical parameters that account for most variations in water quality in the Mukuvisi and Gwebi Rivers. PCA identified sulphate, chloride, fluoride, iron, manganese and zinc as the major factors contributing to the variability of Mukuvisi River water quality. In the Gwebi river, sulphate, nitrate, fluoride and copper accounted for most of the variation in water quality. Canonical Correspondence Analysis (CCA) was used to explore the relationship between physico-chemical parameters and macroinvertebrate communities. CCA plots in both Mukuvisi and Gwebi Rivers showed significant relationships between macroinvertebrate communities and water quality variables. Phosphate, ammonia and nitrates were correlated with Chironomidae and Simulidae. Gwebi River had higher (P<0.05, ANOVA) macroinvertebrates and fish diversity than Mukuvisi River. Clarias gariepinus from the Mukuvisi River had high liver histological lesions and low AChE activity and this led to lower growth rates in this river.


      PubDate: 2015-11-02T13:39:32Z
       
  • The Cone Penetration Test and 2D Imaging Resistivity as Tools to Simulate
           the Distribution of Hydrocarbons in Soil
    • Abstract: Publication date: Available online 31 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M. Pérez-Corona, J.A. García, G. Taller, D. Polgár, E. Bustos, Z. Plank
      The purpose of geophysical electrical surveys is to determine the subsurface resistivity distribution by making measurements on the ground surface. From these measurements, the true resistivity of the subsurface can be estimated. The ground resistivity is related to various geological parameters, such as the mineral and fluid content, porosity and degree of water saturation in the rock. Electrical resistivity surveys have been used for many decades in hydrogeological, mining and geotechnical investigations. More recently, they have been used for environmental surveys. To obtain a more accurate subsurface model than is possible with a simple 1-D model, a more complex model must be used. In a 2-D model, the resistivity values are allowed to vary in one horizontal direction (usually referred to as the x direction) but are assumed to be constant in the other horizontal (the y) direction. A more realistic model would be a fully 3-D model where the resistivity values are allowed to change in all three directions. In this research, a simulation of the cone penetration test and 2D imaging resistivity are used as tools to simulate the distribution of hydrocarbons in soil.
      Graphical abstract image

      PubDate: 2015-11-02T13:39:32Z
       
  • Superhydrophobic and superoleophillic surface of porous beaded electrospun
           polystrene and polysytrene-zeolite fiber for crude oil-water separation
    • Abstract: Publication date: Available online 9 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): S.Oluwagbemiga Alayande, E.Olugbenga Dare, Titus A.M. Msagati, A.Kehinde Akinlabi, P.O. Aiyedun
      This research presents a cheap route procedure for the preparation of a potential adsorbent with superhydrophobic/superoleophillic properties for selective removal of crude oil from water. In this study, expanded polystyrene (EPS) was electrospun to produce beaded fibers in which zeolite was introduced to the polymer matrix in order to impart rough surface to non-beaded fiber. Films of the EPS and EPS/Zeolite solutions were also made for comparative study. The electrospun fibers EPS, EPS/Zeolite and resultant films were characterized using SEM, BET, FTIR and optical contact angle. The fibers exhibited superhydrophobic and superoleophillic wetting properties with water (>150 0) and crude oil (0 0). The selective removal of crude oil presents new opportunity for the re-use of EPS as adsorbent in petroleum/petrochemical industry.


      PubDate: 2015-10-12T11:28:29Z
       
  • Implementing Integrated Catchment Management in the upper Limpopo River
           basin: A Situational Assessment
    • Abstract: Publication date: Available online 9 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J. Mwenge Kahinda, R. Meissner, F.A. Engelbrecht
      A three-phase study was initiated as a way to promote Integrated Catchment Management approaches in the Limpopo River basin. This paper presents the situational assessment, which should enable De Beers to understand how their Venetia Mine operations are located within a broader and highly dynamic socio-economic and ecohydrological landscape as it pertains to water risks. The second phase, Risk assessment, aims to develop conservation interventions in the identified areas; the third phase will develop mechanisms for implementing water stewardship schemes to mitigate the shared water risks. Analysis of the social-ecological system (hydrological, climatic, ecological, socio-economic and governance systems) of the Limpopo River basin indicates that the institutional arrangement of the Limpopo River basin is neither simple nor effective. The basin is rapidly approaching closure in the sense that almost all of the available supplies of water have already been allocated to existing water users. If the proposed ecological flow requirements were to be met for all of the tributaries, the basin would be ‘closed’. On-going and projected land use changes and water resources developments in the upper reaches of the basin, coupled with projected rainfall reductions and temperature increases, and allocation of the flows for the ecological reserve, are likely to further reduce downstream river flows. The coupled increase in temperature and decrease in rainfall is of great concern for everyone in the basin, especially the poorer communities, who rely on rain-fed agriculture for their livelihoods. Increased temperatures also lead to increased evaporation from reservoirs and therefore result in a decrease in water availability. This will lead to increased abstraction of groundwater, especially from alluvial aquifers, and consequently an increase in river transmission losses and a decrease in river flows.


      PubDate: 2015-10-12T11:28:29Z
       
  • Gender and power contestations over water use in irrigation schemes:
           Lessons from the lake Chilwa basin
    • Abstract: Publication date: Available online 9 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Bryson Nkhoma, Gift Kayira
      Over the past two decades, Malawi has been adversely hit by climatic variability and changes, and irrigation schemes which rely mostly on water from rivers have been negatively affected. In the face of dwindling quantities of water, distribution and sharing of water for irrigation has been a source of contestations and conflicts. Women who constitute a significant section of irrigation farmers in schemes have been major culprits. The study seeks to analyze gender contestations and conflicts over the use of water in the schemes developed in the Lake Chilwa basin, in southern Malawi. Using oral and written sources as well as drawing evidence from participatory and field observations conducted at Likangala and Domasi irrigation schemes, the largest schemes in the basin, the study observes that women are not passive victims of male domination over the use of dwindling waters for irrigation farming. They have often used existing political and traditional structures developed in the management of water in the schemes to competitively gain monopoly over water. They have sometimes expressed their agency by engaging in irrigation activities that fall beyond the control of formal rules and regulations of irrigation agriculture. Other than being losers, women are winning the battle for water and land resources in the basin.


      PubDate: 2015-10-12T11:28:29Z
       
  • Daily Surface Water and Sediment Fluxes in Thukela River, South Africa
    • Abstract: Publication date: Available online 9 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Macdex Mutema, Graham Jewitt, Pauline Chivenge, Samuel Kusangaya, Vincent Chaplot
      The on- and off-site effects of soil erosion in many environments are well known, but there is still limited understanding of the fluxes in downstream direction due, among other factors, to scarce and poor quality data. A study four year to (i) evaluate water and sediment fluxes at different spatio-temporal scales and (ii) interpret the results in terms of processes involved and the controlling factors, was conducted in Thukela basin, South Africa. Five hierarchically nested catchments; namely microcatchment (0.23 km2), subcatchment (1.20 km2), catchment (9.75 km2), sub-basin (253 km2) and basin (29038 km2), were used in addition to fifteen (1 m2) microplots and ten (10 m2) plots on five locations within the microcatchment. The results showed 19% decrease of unit-area runoff (q) from 3.1 L m-2 day-1 at microplot to 2.5 L m-2 day-1 at plot scale followed by steeper (56%) decrease at microcatchment scale. The q decreased in the downstream direction to very low level (q ≤ 0.26 L m-2 day-1). The changes in q were accompanied by initial 1% increase of soil loss (SL) from 18.8 g m-2 day-1 at microplot to 19.1 g m-2 day-1 at plot scale. The SL also decreased sharply (by 39 fold) to 0.50 g m-2 day-1 at microcatchment scale, followed by further decrease in downstream direction. The decrease of q with spatial scale was attributed to infiltration losses, while initial increase of SL signified greater competence of sheet than splash erosion. The decrease of SL beyond the plot scale was attributed to redistribution of the soil on the hillslope and deposition on the stream channel upstream of the microcatchment outlet. Therefore, erosion control strategies focusing on the recovery of vegetation on the slope and stabilisation of gullies are recommended.


      PubDate: 2015-10-12T11:28:29Z
       
  • Effect of iron salt counter ion in dose-response curves for inactivation
           of Fusarium solani in water through solar driven Fenton-like processes
    • Abstract: Publication date: Available online 9 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Verónica Aurioles-López, M. Inmaculada Polo-López, Pilar Fernández-Ibáñez, Aurelio López-Malo, Erick R. Bandala
      The inactivation of Fusarium solani in water was assessed by solar driven Fenton-like processes using three different iron salts: ferric acetylacetonate (Fe(acac)3), ferric chloride (FeCl3) and ferrous sulfate (FeSO4). The experimental conditions tested were [Fe] ≈ 5 mg L-1, [H2O2] ≈ 10 mg L-1 and [Fe] ≈10 mg L-1; [H2O2] ≈20 mg L-1 mild and high, respectively, and pH 3.0 and 5.0, under solar radiation. The highest inactivation rates were observed at high reaction conditions for the three iron salts tested at pH 5.0 with less than 3.0 kJL-1 of accumulate energy (Q UV ) to achieve over 99.9% of F. solani inactivation. Fe(acac)3 was the best iron salt to accomplishing F. solani inactivation. The modified Fermi equation was used to fix the experimental inactivation, data showed it was helpful for modeling the process, adequately describing dose-response curves. Inactivation process using FeSO4 at pH 3.0 was modeled fairly with r 2 = 0.98 and 0.99 (mild and high concentration, respectively). Fe(acac)3, FeCl3 and FeSO4 at high concentration (i.e. [Fe]≈10 mgL-1; [H2O2]≈20 mgL-1) and pH 5.0 showed the highest fitting values (r 2 = 0.99). Iron salt type showed a remarkable influence on the Fenton-like inactivation process.


      PubDate: 2015-10-12T11:28:29Z
       
  • A diagnosis of sub-surface water table dynamics in low hydraulic
           conductivity soils in the sugar cane fields of Pongola, South Africa
    • Abstract: Publication date: Available online 9 October 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Mphatso Malota, Aidan Senzanje
      Water and land are the two natural resources restraining crop production in South Africa. With the increasing demand for food, emphasis has shifted from the sole reliance on rain fed crop production, to irrigation. The deterioration in irrigation water quality from surface water sources is, however, posing a big challenge to the sustainability of irrigated crop production. This is because more water is required for leaching, resulting in shallow water tables in agricultural lands. The installation of well designed subsurface drainage systems alone is not enough; the provision of timely maintenance is also necessary. In this study, the extent and severity of problems as a consequence of shallow water tables and their possible causes were investigated at three sugarcane fields in Pongola, South Africa, having low hydraulic conductivity soils. Also investigated were soil salinity levels and the temporal variation in the salinity of the irrigation water. A water table map of a 32 ha sugarcane field was generated, using observed water table depth (WTD) data from 36 piezometers monitored from September 2011 to February 2012. Out of the total 32 ha under cultivation, 12% was found to be affected by shallow WTDs of less than the 1.0 m design WTD. The inability of natural drainage to cope with subsurface drainage needs and the poor maintenance of subsurface drainage systems contributed to the shallow water tables in the area. Furthermore, the currently adopted drainage design criteria also proved unsatisfactory with mean observed water table depth and drainage discharge (DD) of 20% and 50%, respectively, less than their respective design levels. The salinity of the irrigation water was, on average, 32% higher than threshold tolerance level of sugarcane. The root zone soil salinity levels at the three study sites were greater than the 1.7 dS.m-1 threshold for sugar cane. The subsurface drainage design criteria adopted at the site needs to be revisited by ensuring that the slope of the land is taken into consideration in the drainage design in addition to adhering to a recommended maintenance schedule.


      PubDate: 2015-10-12T11:28:29Z
       
  • Climate threats, water supply vulnerability and the risk of a water crisis
           in the Monterrey Metropolitan Area (Northeastern Mexico)
    • Abstract: Publication date: Available online 29 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Nicholas P. Sisto, Aldo I. Ramírez, Ismael Aguilar-Barajas, Víctor Magaña-Rueda
      This paper evaluates the risk of a water crisis – a substantial, sudden reduction in water supply - in the Monterrey Metropolitan Area (MMA), posed by climate threats and the vulnerability of its water supply system. Our analysis of long-term precipitation, water supply and water availability data reveals that the MMA is highly vulnerable to recurring periods of exceptionally low precipitation and scarce surface water availability. We identify two episodes in the recent past (1998 and 2013) when the MMA water supply system almost collapsed as reservoirs neared depletion in the face of abnormally dry weather. Furthermore our climate projections point to warmer and drier future conditions for the region and consequently, heightened climate threats. We conclude that the risk of a water crisis in the MMA is substantial and probably will increase due to climate change. This establishes a clear and pressing need for a comprehensive package of adaptation measures to mitigate the consequences of a water crisis should one occur as well as to reduce the likelihood of such an event.


      PubDate: 2015-08-31T06:09:29Z
       
  • Possible Climate Change Evidence in Ten Mexican Watersheds
    • Abstract: Publication date: Available online 29 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Efrain Mateos, Julio-Sergio Santana, Martin J Montero-Martínez, Alejandro Deeb, Alfred Grunwaldt
      This paper suggests possible evidence of climate change in Mexico at the watershed level, based solely on historical data. The official Mexican climate dataset was used to find the best set of stations for each watershed. Maximum and minimum temperatures and rainfall in ten watersheds are analyzed from 1970 to 2009. Maximum temperature trends show a significant increment in most of these watersheds. Furthermore, Daily Temperature Range (DTR) exhibits a positive trend (increments), thus implying an increase in temperature extremes. This study also shows that the difference between maximum and minimum monthly temperature trends is negatively correlated with monthly precipitation trends. As a result, land-use and land-cover changes could be the main drivers of climate change in the region.


      PubDate: 2015-08-31T06:09:29Z
       
  • Review and discussion of homogenisation methods for climate data
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): S. Ribeiro, J. Caineta, A.C. Costa
      The quality of climate data is of extreme relevance, since these data are used in many different contexts. However, few climate time series are free from non-natural irregularities. These inhomogeneities are related to the process of collecting, digitising, processing, transferring, storing and transmitting climate data series. For instance, they can be caused by changes of measuring instrumentation, observing practices or relocation of weather stations. In order to avoid errors and bias in the results of analysis that use those data, it is particularly important to detect and remove those non-natural irregularities prior to their use. Moreover, due to the increase of storage capacity, the recent gathering of massive amounts of weather data implies also a toilsome effort to guarantee its quality. The process of detection and correction of irregularities is named homogenisation. A comprehensive summary and description of the available homogenisation methods is critical to climatologists and other experts, who are looking for a homogenisation method wholly considered as the best. The effectiveness of homogenisation methods depends on the type, temporal resolution and spatial variability of the climatic variable. Several comparison studies have been published so far. However, due to the absence of time series where irregularities are known, only a few of those comparisons indicate the level of success of the homogenisation methods. This article reviews the characteristics of the most important procedures used in the homogenisation of climatic variables based on a thorough literature research. It also summarises many methods applications in order to illustrate their applicability, which may help climatologists and other experts to identify adequate method(s) for their particular needs. This review study also describes comparison studies, which evaluated the efficiency of homogenisation methods, and provides a summary of conclusions and lessons learned regarding good practices for the use of homogenisation methods.


      PubDate: 2015-08-31T06:09:29Z
       
  • Geochemical modelling and speciation studies of metal pollutants present
           in selected water systems in South Africa
    • Abstract: Publication date: Available online 28 August 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.M. Magu, P.P. Govender, J.C. Ngila
      Metal pollutants in water poses great threats to living beings and hence requires to be monitored regularly to avoid loss of lives. Various analytical methods are available to monitor these pollutants in water and can be improved with time. Modelling of metal pollutants in any water system helps chemists, engineers and environmentalists to greatly understand the various chemical processes in such systems. Water samples were collected from waste water treatment plant and river from highlands close to its source all the way to the ocean as it passing through areas with high anthropogenic activities. Pre-concentration of pollutants in the samples was done through acid digestion and metal pollutants were analysed using inductively coupled plasma-optical emission spectra (ICP-OES) to determine the concentration levels. Metal concentrations ranged between 0.1356–0.4658mg/L for Al; 0.0031–0.0050mg/L for Co, 0.0019–0.0956mg/L for Cr; 0.0028–0.3484mg/L for Cu; 0.0489–0.3474mg/L for Fe; 0.0033–0.0285mg/L for Mn; 0.0056–0.0222mg/L for Ni; 0.0265–0.4753mg/L for Pb and 0.0052–0.5594mg/L for Zn. Modelling work was performed using PHREEQC couple with Geochemist’s workbench (GWB) to determine speciation dynamics and bioavailability of these pollutants. Modelling thus adds value to analytical methods and hence a better complementary tool to laboratory-based experimental studies.


      PubDate: 2015-08-31T06:09:29Z
       
 
 
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