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PHYSICS (563 journals)            First | 1 2 3 4 5 6 | Last

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: 7)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin     Hybrid Journal   (Followers: 4)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 12)
Nuclear Medicine and Biology     Hybrid Journal   (Followers: 1)
Nuclear Receptor     Full-text available via subscription   (Followers: 1)
Open Journal of Biophysics     Open Access   (Followers: 1)
Open Journal of Fluid Dynamics     Open Access   (Followers: 3)
Open Journal of Microphysics     Open Access  
Optical Communications and Networking, IEEE/OSA Journal of     Hybrid Journal   (Followers: 5)
Optofluidics, Microfluidics and Nanofluidics     Open Access   (Followers: 1)
Organic Electronics     Hybrid Journal   (Followers: 3)
Organic Photonics and Photovoltaics     Open Access   (Followers: 2)
PAJ: A Journal of Performance and Art     Hybrid Journal   (Followers: 12)
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: 5)
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)
Physical Communication     Hybrid Journal  
Physical Review C     Full-text available via subscription   (Followers: 18)
Physical Review Special Topics - Physics Education Research     Open Access   (Followers: 6)
Physical Review X     Open Access   (Followers: 6)
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: 2)
Physics and Chemistry of Liquids: An International Journal     Hybrid Journal   (Followers: 2)
Physics and Chemistry of the Earth, Parts A/B/C     Hybrid Journal   (Followers: 3)
Physics and Materials Chemistry     Open Access  
Physics Essays     Full-text available via subscription  
Physics in Medicine & Biology     Full-text available via subscription   (Followers: 10)
Physics in Perspective     Hybrid Journal   (Followers: 1)
Physics International     Open Access   (Followers: 2)
Physics Letters A     Hybrid Journal   (Followers: 9)
Physics Letters B     Open Access   (Followers: 3)
Physics of Fluids     Hybrid Journal   (Followers: 24)
Physics of Life Reviews     Hybrid Journal   (Followers: 1)
Physics of Plasmas     Hybrid Journal   (Followers: 6)
Physics of the Dark Universe     Open Access  
Physics of the Solid State     Hybrid Journal   (Followers: 3)
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: 34)
Physics World     Full-text available via subscription   (Followers: 3)
Physics-Uspekhi     Full-text available via subscription  
Physik in unserer Zeit     Hybrid Journal  
Physik Journal     Hybrid Journal  
Plasma Physics and Controlled Fusion     Hybrid Journal   (Followers: 2)
Plasma Physics Reports     Hybrid Journal   (Followers: 2)
Pramana     Open Access   (Followers: 9)
Preview     Hybrid Journal  
Proceedings of the National Academy of Sciences     Full-text available via subscription   (Followers: 540)
Proceedings of the National Academy of Sciences, India Section A     Hybrid Journal   (Followers: 3)
Progress in Materials Science     Hybrid Journal   (Followers: 20)
Progress in Planning     Hybrid Journal   (Followers: 1)
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  
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: 3)
Radiological Physics and Technology     Hybrid Journal   (Followers: 1)
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)
Reviews of Modern Physics     Full-text available via subscription   (Followers: 17)
Revista Colombiana de Física     Open Access  
Revista Mexicana de Astronomía y Astrofísica     Open Access  
Revista Mexicana de Física     Open Access  
Revista mexicana de física E     Open Access  
Rheologica Acta     Hybrid Journal   (Followers: 3)
Russian Journal of Mathematical Physics     Hybrid Journal  
Russian Journal of Nondestructive Testing     Hybrid Journal   (Followers: 1)
Russian Physics Journal     Hybrid Journal  
Samuel Beckett Today/Aujourd'hui     Full-text available via subscription   (Followers: 2)
Science and Technology of Nuclear Installations     Open Access   (Followers: 1)

  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]   [5 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1474-7065
   Published by Elsevier Homepage  [2588 journals]
  • Changes in Animal Activity Prior to a Major (M=7) Earthquake in the
           Peruvian Andes
    • Abstract: Publication date: Available online 17 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Rachel A. Grant , Jean Pierre Raulin , Friedemann T. Freund
      During earthquake preparation geophysical processes occur over varying temporal and spatial scales, some leaving their mark on the surface environment, on various biota, and even affecting the ionosphere. Reports on pre-seismic changes in animal behaviour have been greeted with scepticism by the scientific community due to the necessarily anecdotal nature of much of the evidence and a lack of consensus over possible causal mechanisms. Here we present records of changes in the abundance of mammals and birds obtained over a 30 day period by motion-triggered cameras at the Yanachaga National Park, Peru, prior to the 2011 magnitude 7.0 Contamana earthquake. In addition we report on ionospheric perturbations derived from night-time very low frequency (VLF) phase data along a propagation paths passing over the epicentral region. Animal activity declined significantly over a 3-week period prior to the earthquake compared to periods of low seismic activity. Night-time ionospheric phase perturbations of the VLF signals above the epicentral area, fluctuating over the course of a few minutes, were observed, starting 2 weeks before the earthquake. The concurrent observation of two widely different and seemingly unconnected precursory phenomena is of interest because recently, it has been proposed that the multitude of reported pre-earthquake phenomena may arise from a single underlying physical process: the stress-activation of highly mobile electronic charge carriers in the Earth’s crust and their flow to the Earth’s surface. The flow of charge carriers through the rock column constitutes and electric current, which is expected to fluctuate and thereby emit electromagnetic radiation in the ultralow frequency (ULF) regime. The arrival of the charge carriers can lead to air ionization at the ground-to-air interface and the injection of massive amounts of positive airborne ions, known to be aversive to animals.

      PubDate: 2015-03-18T09:21:50Z
  • Precursory signatures in the visibility graph analysis of seismicity: an
           application to the Kachchh (Western India) seismicity
    • Abstract: Publication date: Available online 14 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Luciano Telesca , Michele lovallo , S.K. Aggarwal , P.K. Khan
      The Visibility Graph (VG) method maps time series into networks or graphs, converting dynamical properties of time series in topological properties of networks. The VG method was applied to the aftershock depleted catalogue of the Kachchh Gujarat (Western India) seismicity from 2003 to 2012, in order to identify possible precursory signatures in the pattern of the VG parameters. The k-M slope (the slope of the line fitting the relationship between the magnitude of the events and their connectivity degrees) seems to sharply increase significantly before the occurrence of the largest shocks (M⩾4.5) of the sequence.

      PubDate: 2015-03-18T09:21:50Z
  • A Temperature-Dependent Multi-Relaxation Spectroscopic Dielectric Model
           for Thawed and Frozen Organic Soil at 0.05-15 GHz
    • Abstract: Publication date: Available online 14 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Valery Mironov , Igor Savin
      A dielectric model for thawed and frozen Arctic organic-rich soil (50% organic matter) has been developed. The model is based on soil dielectric measurements that were collected over ranges of gravimetric moisture from 0.03 to 0.55 g/g, dry soil density from 0.72 to 0.87 g/cm3, and temperature from 25 to -30°C (cooling run) in the frequency range of 0.05-15 GHz. The refractive mixing dielectric model was applied with the Debye multi-relaxation equations to fit the measurements of the soil’s complex dielectric constant as a function of soil moisture and wave frequency. The spectroscopic parameters of the dielectric relaxations for the bound, transient bound, and unbound soil water components were derived and were complimented by the thermodynamic parameters to obtain a complete set of parameters for the proposed temperature-dependent multi-relaxation spectroscopic dielectric model for moist soils. To calculate the complex dielectric constant of the soil, the following input variables must be assigned: 1) density of dry soil, 2) gravimetric moisture, 3) wave frequency, and 4) temperature. The error of the dielectric model was evaluated and yielded RMSE ε’ values of 0.348 and 0.188 for the soil dielectric constant and the loss factor, respectively. These values are on the order of the dielectric measurement error itself. The proposed dielectric model can be applied in active and passive microwave remote sensing techniques to develop algorithms for retrieving the soil moisture and the freeze/thaw state of organic-rich topsoil in the Arctic regions.

      PubDate: 2015-03-18T09:21:50Z
  • A Model of the generation of electromagnetic emissions detected prior to
    • Abstract: Publication date: Available online 16 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.K. Kachakhidze , N.K. Kachakhidze , T.D. Kaladze
      Recent satellite and ground-based observations prove that during the formative period of earthquakes VLF/LF and ULF electromagnetic emissions are observed in seismogenic areas. This work offers an original model of self-generated electromagnetic oscillations of local segments of the lithospheric origins of the emissions. In the paper, the seismogenic area is considered to be an oscillatory- distributed system. This model simplifies physical analyses of the nonlinear effects and qualitatively explains the mechanisms that generate very low frequency electromagnetic waves in the period prior to an earthquake.

      PubDate: 2015-03-18T09:21:50Z
  • Anomalous CO2 content in the Gallicano thermo-mineral spring (Serchio
           Valley, Italy) before the 21 June 2013, Alpi Apuane Earthquake (M = 5.2)
    • Abstract: Publication date: Available online 14 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): L. Pierotti , F. Botti , V. D’Intinosante , G. Facca , F. Gherardi
      Since late 2002, a continuous automatic monitoring network is operating in Tuscany, Central Italy, to investigate the geochemical response of selected aquifers to local seismic activity. The monitoring is aimed at identifying possible earthquake geochemical precursors. The network is currently constituted by six stations, all equipped with sensors for the measurement of temperature, pH, redox potential, electrical conductivity, CO2 and CH4 dissolved concentration, that have been installed in the areas of highest seismic risk of the region. By combining geochemical data gathered from the automatic station of Gallicano (Garfagnana, Northern Tuscany), and obtained via chemical analyses of spring water samples collected during periodic field surveys in the area surrounding this station, the most significant aspects of the deep fluid circulation paths feeding the Gallicano thermo-mineral system have been investigated, and the geochemical baseline of the Gallicano spring defined. The CO2 continuous signal recorded by the Gallicano automatic station has been then processed over the period 2003 to 2013 in the search for anomalies possibly related to local seismic activity. A substantial anomaly in CO2 content has been observed at Gallicano in conjunction with the Alpi Apuane earthquake (M=5.2) of 21 June 2013.

      PubDate: 2015-03-14T09:05:30Z
  • Surface Soil Moisture Retrievals from Remote Sensing: Current Status,
           Products & Future Trends
    • Abstract: Publication date: Available online 14 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): George P. Petropoulos , Gareth Ireland , Brian Barrett
      Advances in Earth Observation (EO) technology, particularly over the last two decades, have shown that soil moisture content (SMC) can be measured to some degree or other by all regions of the electromagnetic spectrum, and a variety of techniques have been proposed to facilitate this purpose. In this review we provide a synthesis of the efforts made during the last 20 years or so towards the estimation of surface SMC exploiting EO imagery, with a particular emphasis on retrievals from microwave sensors. Rather than replicating previous overview works, we provide a comprehensive and critical exploration of all the major approaches employed for retrieving SMC in a range of different global ecosystems. In this framework, we consider the newest techniques developed within optical and thermal infrared remote sensing, active and passive microwave domains, as well as assimilation or synergistic approaches. Future trends and prospects of EO for the accurate determination of SMC from space are subject to key challenges, some of which are identified and discussed within. It is evident from this review that there is potential for more accurate estimation of SMC exploiting EO technology, particularly so, by exploring the use of synergistic approaches between a variety of EO instruments. Given the importance of SMC in Earth’s land surface interactions and to a large range of applications, one can appreciate that its accurate estimation is critical in addressing key scientific and practical challenges in today’s world such as food security, sustainable planning and management of water resources. The launch of new, more sophisticated satellites strengthens the development of innovative research approaches and scientific inventions that will result in a range of pioneering and ground-breaking advancements in the retrievals of soil moisture from space.

      PubDate: 2015-03-14T09:05:30Z
  • An experiment on temperature variations in sandstone during biaxial
    • Abstract: Publication date: Available online 1 November 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Shunyun Chen , Peixun Liu , Yanshuang Guo , Liqiang Liu , Jin Ma
      The temperature response to stress–strain variations in rock is useful in developing an understanding of the thermodynamic property of crust. In this study, the temperature of sandstone during loading was investigated using laboratory biaxial testing. By changing the loading patterns, the deformation of a specimen was controlled to produce two distinct modes of strain: volume strain only and shear strain only. These strain modes were produced separately such that the temperature variation associated with the different deformation modes could be analysed. Experimental results indicate that temperature, as a scalar quantity, is notably sensitive to rock deformation. In the case of the volume strain, the temperature variation is positively correlated with the variation in the bulk stress. The temperature rises with the increase in hydrostatic pressure, and vice versa. In the case of the shear strain, experimental results repeatedly show two characteristics: firstly, there appears obvious increase in temperature in the area of pure shear strain, which is most likely related to local plastic deformation; secondly, the temperature drops in the area of tension during loading, whereas the temperature rises within the area of compression. This is to say, the state of crustal stress–strain should be obtained through the measurement of rock temperature.

      PubDate: 2015-03-10T08:35:25Z
  • Predictive complexation models of the impact of natural organic matter and
           cations on scaling in cooling water pipes: a case study of power
           generation plants in South Africa
    • Abstract: Publication date: Available online 12 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): G.O Bosire , J.C. Ngila , J.M Mbugua
      This work discusses simulative models of Ca and Mg complexation with natural organic matter (NOM), in order to control the incidence of scaling in pipes carrying cooling water at the Eskom power generating stations in South Africa. In particular, the paper reports how parameters such as pH and trace element levels influence the distribution of scaling species and their interactions, over and above mineral phase saturation indices. In order to generate modelling inputs, two experimental scenarios were created in the model solutions: Firstly, the trace metals Cu, Pb and Zn were used as markers for Ca and Mg complexation to humic acid and secondly the effect of natural organic matter in cooling water was determined by spiking model solutions. Labile metal ions and total elements in model solutions and water samples were analysed by square wave anodic stripping voltammetry and inductively coupled plasma optical emission spectrometry (ICP-OES), respectively. ICP-OES results revealed high levels of K, Na, S, Mg and Ca and low levels of trace elements (Cd, Se, Pb, Cu, Mn, Mo, Ni, Al and Zn) in the cooling water samples. Using the Tipping and Hurley’s database WHAM in PHREEQC format (T-H.DAT), the total elemental concentrations were run as inputs on a PHREEQC code, at pH 6.8 and defined charge as alkalinity (as HCO 3 - For model solutions, PHREEQC inputs were based on (i) free metal differences attributed to competitive effect of Ca and the effect of Ca+Mg, respectively; (ii) total Ca and Mg used in the model solutions and (iii) alkalinity described as hydrogen carbonate. Anodic stripping peak heights were used to calculate the concentration of the free/uncomplexed/labile metal ions (used as tracers) in the model solutions. The objective of modelling was to describe scaling in terms of saturation indices of mineral phases. Accordingly, the minerals most likely to generate scale were further simulated (over a range of pH (3-10) to yield results that mimicked changing pH. Speciation calculations of Cu2+, Pb2+ and Zn2+ generated azurite, cerrusite and smithsonite mineral phases, which showed positive saturation indices at higher pH, hence increased potential to precipitate (form scale). The derived predictive models would act as a useful management tool and henceforth aid to avoid unnecessary costs due to the consequences of scaling.

      PubDate: 2015-03-10T08:35:25Z
  • An analysis of the effectiveness of WASH interventions in relation to
           diarrhoeal diseases in Chipinge district, Zimbabwe
    • Abstract: Publication date: Available online 12 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): T. Demberere , M. Muyambo , S. Mutengu , T. Ncozana , N. Manyeruke
      A study to analyse the effectiveness of WASH interventions in mitigating diarrhoeal diseases in ward 22 of Chipinge district, Manicaland Province was done in 2012. The objectives of the study were to determine the existing WASH interventions in the ward, to assess the KAP on WASH interventions as a mitigation measure against diarrhoeal disease, to analyse the trend of diarrhoea from 2005 to 2011 and to analyse the behaviour change attributed to WASH interventions. Data was collected using interviews, questionnaires, FGDs and observation checklists. Data was analysed using SPSS version 16.0 and qualitative data was analysed by developing themes related to specific objectives. Results showed that WASH interventions were in place in all the villages of ward 22 though they were inadequate. The interventions among others included borehole rehabilitation, latrine construction and Participatory Health and Hygiene Education (PHHE). The cases of diarrhoea were on the increase between 2005 and 2011 despite the various WASH interventions. It was also noted that, although the communities had knowledge on good hygiene practices, economic hardships prevented them from practicing. Behaviour change was also noticed due to an increase in the number of households with hygiene enabling facilities. It was concluded that there is need to provide more water supply and sanitation facilities in the ward. Nurses and EHTs in the ward need to intensify on Health and hygiene education. It was recommended that the duration for PHHE sessions be lengthened and that Village Health Clubs should be formed for sustainability of the health and hygiene component of the interventions. Participation of vulnerable groups such as the disabled, People Living with HIV and AIDS and child headed families should also be encouraged as their participation was seen to be very low, yet their contribution in the society is very critical.

      PubDate: 2015-03-10T08:35:25Z
  • Ionospheric activity and possible connection with seismicity: Contribution
           from the analysis of long time series of GNSS signals
    • Abstract: Publication date: Available online 1 November 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Francesco Mancini , Angelo Galeandro , Michaela De Giglio , Maurizio Barbarella
      The modifications of some atmospheric physical properties prior to a high magnitude earthquake were debated in the frame of the Lithosphere Atmosphere Ionosphere Coupling (LAIC) model. In this work, among the variety of involved phenomena, the ionisation of air at the ionospheric levels triggered by the leaking of gases from the Earth’s crust was investigated through the analysis of GNSS (Global Navigation Satellite System) signals. In particular, the authors analysed a 5year (2008–2012) long series of GNSS based ionospheric TEC to produce maps over an area surrounding the epicentre of the L’Aquila (Italy, M w =6.3) earthquake of April 6th, 2009. The series was used to detect and quantify amplitude and duration of episodes of ionospheric disturbances by a statistical approach and to discriminate local and global effects on the ionosphere comparing these series with TEC values provided by the analysis of GNSS data from international permanent trackers distributed over a wider region. The study found that during this time interval only three statistically meaningful episodes of ionospheric disturbances were observed. One of them, occurring during the night of 16th of March 2009, anticipated the main shock by 3weeks and could be connected with the strong earthquake of 6th of April. The other two significant episodes were detected within periods that were not close to the main seismic events and are more likely due to various and global reasons.

      PubDate: 2015-03-10T08:35:25Z
  • Pathways for building capacity and ensuring effective transboundary water
           resources management in Africa: Revisiting the key issues, opportunities
           and challenges
    • Abstract: Publication date: Available online 12 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Claudious Chikozho
      The performance of most organizations and institutions set up to facilitate transboundary water resources management in Africa remains unsatisfactory and new frameworks are required to address this performance gap. Using the Nile and Senegal River Basins as case studies, this paper applies qualitative research methods to explore the transboundary river basin management terrain in Africa with a view to identifying and articulating some of the major issues, challenges and opportunities faced in building the capacity of the main actors and institutions in the sector. The paper establishes that the creation of basin management institutions as the assumed panacea to challenges evident in this sector has not delivered the desired results. Some of the institutions established for this purpose in Africa have remained functionally weak and ineffective. Thus, demand for capacity-building interventions in this landscape remains high. The paper concludes that comprehensive capacity-building interventions should seek to improve the competencies and skills of key actors in implementing the broad range of activities constituting integrated water resources management in transboundary basins. In-depth analysis of the fundamental capacity constraints and challenges that key players face in relation to key drivers for cooperation is the absolutely necessary ingredient.

      PubDate: 2015-03-10T08:35:25Z
  • Fractionation of wastewater characteristics for modelling of Firle Sewage
           Treatment Works, Harare, Zimbabwe
    • Abstract: Publication date: Available online 14 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Simon Takawira Muserere , Zvikomborero Hoko , Innocent Nhapi
      Varying conditions are required for different species of microorganisms for the complex biological processes taking place within the activated sludge treatment system. It is against the requirement to manage this complex dynamic system that computer simulators were developed to aid in optimising activated sludge treatment processes. These computer simulators require calibration with quality data input that include wastewater fractionation among others. Thus, this research fractionated raw sewage, at Firle Sewage Treatment Works (STW), for calibration of the BioWin simulation model. Firle STW is a 3-stage activated sludge system. Wastewater characteristics of importance for activated sludge process design can be grouped into carbonaceous, nitrogenous and phosphorus compounds. Division of the substrates and compounds into their constituent fractions is called fractionation and is a valuable tool for process assessment. Fractionation can be carried out using bioassay methods or much simpler physico-chemical methods. The bioassay methods require considerable experience with experimental activated sludge systems and associated measurement techniques while the physico-chemical methods are straight forward. Plant raw wastewater fractionation was carried out through two 14-day campaign periods, the first being from 3 to 16 July 2013 and the second was from 1 to 14 October 2013. According to the Zimbabwean Environmental Management Act, and based on the sensitivity of its catchment, Firle STW effluent discharge regulatory standards in mg/L are COD (<60), TN (<10), ammonia (<0.2), and TP (<1). On the other hand Firle STW Unit 4 effluent quality results based on City of Harare records in mg/L during the period of study were COD (90±35), TN (9.0±3.0), ammonia (0.2±0.4) and TP (3.0±1.0). The raw sewage parameter concentrations measured during the study in mg/L and fractions for raw sewage respectively were as follows total COD (680±37), slowly biodegradable COD (456±23), (0.7), readily biodegradable COD (131±11), (0.2), soluble unbiodegradable COD (40±3), (0.06), particulate unbiodegradable COD (53±3) (0.08), total TKN (40±4) mg/L, ammonia (28±6), (0.68), organically bound nitrogen (12±2), (0.32), TP (15±1.4), orthophosphates (9.6±1.4), (0.64), and organically bound TP (5.4±1.4), (0.36), soluble unbiodegradable TP (0.4±0), (0.03), particulate unbiodegradable TP (0.05±0), (0.003). Thus, wastewater at Firle STW was found to be highly biodegradable suggesting optimisation of biological nutrient removal process will generally achieve effluent regulatory standards compliance. Thus, opportunities for plant optimisation do exist of which modelling with the use of a simulator is recommended to achieve recommended effluent standards in addition to reduction of operating costs.

      PubDate: 2015-03-10T08:35:25Z
  • River health assessment using macroinvertebrates and water quality
           parameters: a case of the orange river in namibia
    • Abstract: Publication date: Available online 19 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Shishani Munyika , Victor Kongo , Richard Kimwaga
      Land use activities that have an effect on water quality and river health are believed to have increased along the Orange River in Namibia. These are mainly agricultural activities, notably irrigation, with more than 2000 ha currently under irrigation and approximately 2000 ha planned for future expansion. Other anthropogenic activities include urban development and weir construction along the Orange River. Population increase along the river has resulted in proliferation of unplanned settlements with no proper sanitation facilities. This study was aimed at assessing the current water quality and overall health status of the Orange River in Namibia. The South African Scoring System 5(SASS5) was applied in eight sites where samples for macroinvertebrates, physical and chemical water quality parameters such as nutrients in the water, pH, turbidity, presence of bacteria, etc were obtained. Satellite images i.e. Landsat images were also used to assess the land-uses over time in the study area with the view of linking such changes to variance in water quality over time. The SASS5 results indicated a fair water quality and river health condition in category C, indicating that the river is moderately modified. Water quality parameters at all sites varied moderately and were within acceptable limits, except for turbidity and chlorophyll a. There was a significant difference in the mean concentrations of nine water quality parameters among sampling periods, whereby F-value > F-critical at α = 0.05 among sites, F-value < F-critical at α = 0.05, except for turbidity and chlorophyll a. The Landsat images also showed minimal changes in land-use activities between 2002 and 2012, with a net increase of 38 ha in irrigated area. According to National Water Policy White Paper of Namibia of 2000, it was found that policies and legislation address water resources management from a broader spectrum and not specific to river health. Thus, it was concluded that the river health of Orange River is still within acceptable range despite the fact that there is an urgent need to develop an effective and sustainable water quality monitoring and development programme.

      PubDate: 2015-03-10T08:35:25Z
  • Evaluation of sample preparation methods for the detection of total metal
           content using inductively coupled plasma optical emission spectrometry
           (ICP-OES) in wastewater and sludge
    • Abstract: Publication date: Available online 10 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): K.M. Dimpe , J.C. Ngila , N. Mabuba , P.N. Nomngongo
      Heavy metal contamination exists in aqueous wastes and sludge of many industrial discharges and domestic wastewater, among other sources. Determination of metals in the wastewater and sludge requires sample pre-treatment prior to analysis because of certain challenges such as the complexity of the physical state of the sample, which may lead to wrong readings in the measurement. This is particularly the case with low analyte concentration to be detected by the instrument. The purpose of this work was to assess and validate the different sample preparation methods namely, hot plate and microwave-assisted digestion procedures for extraction of metal ions in wastewater and sludge samples prior to their inductively coupled plasma optical emission spectrometric (ICP-OES) determination. For the extraction of As, Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn, three acid mixtures, that is, HNO3/H2O2, HNO3/HClO4/H2O2 and aqua regia+H2O2, were evaluated. Influent wastewater spiked with the SRM (CWW-TM-B) was used for the optimization of acid mixtures affecting the extraction procedure. After sample digestion, the filtration capabilities of cellulose-acetate filter paper and the acrodisc syringe filter with the pore size of 0.45μm were compared. In terms of performance, acrodisc syringe filter in terms of the improved recoveries obtained, was found to be the best filtration method compared to the filter paper. Based on the analytical results obtained, microwave-assisted digestion (MAD) using aqua regia+H2O2 mixture was found to be the most suitable method for extraction of heavy metals and major elements in all the sample matrices. Therefore, MAD using aqua regia+H2O2 mixture was used for further investigations. The precision of the developed MAD method expressed in terms of relative standard deviations (% RSD) for different metals was found to be <5%. The limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.12% to 2.18μgL−1 and 0.61% to 3.43μgL−1, respectively. The accuracy of the developed method (MAD using aqua regia+H2O2) was verified by analyzing two SRMs (CWW-TM-A and CWW-TM-B) and the obtained results were in agreement with certified values with recoveries ranging from 80% to 104% for CWW-TM-A and 84% to 102% for CWW-TM-B. The accuracy of the developed method was verified also by the recovery test in the spiked sludge samples. The accuracy and spike recovery test for different metal ions were in the range 80–104% and 92–106%, respectively. The developed method was applied for extraction of the As, Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn in environmental samples, namely wastewater and sludge.

      PubDate: 2015-03-10T08:35:25Z
  • A qualitative study of seismic-ionospheric precursor phenomena monitored
           by a very close to the epicenter VLF and LF receiver
    • Abstract: Publication date: Available online 5 March 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): C. Skeberis , Z.D. Zaharis , T.D. Xenos , S. Spatalas , M.E. Contadakis
      This work investigates the occurrence of disturbances across a wide range of VLF and LF frequencies received prior to a seismic event (Mw=4), that took place on May 12th 2012, the epicenter of which was very close (14Km) to the VLF/LF station. The signals analysed were emitted from five VLF and five LF European transmitters. This seismic event produced precursory ionospheric disturbances, identified as spectral distortion, three days before its occurrence, providing a distinct pattern open to further investigation. Although the basis of the ionosphere interaction with seismic phenomena has been well documented in previous studies, the close proximity of the receiver to the seismic event provides a new perspective to this study. The monitored signals have undergone normalization and then they have been processed by means of the Hilbert-Huang Transform. Diagrams of the signals relevant to the phenomena are presented and the disturbances that are present in the raw data are accentuated through further processing.

      PubDate: 2015-03-10T08:35:25Z
  • Assessing the regional spatio-temporal pattern of water stress: A case
           study in Zhangye City of China
    • Abstract: Publication date: Available online 6 November 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Qian Zhang , Bing Liu , Weige Zhang , Gui Jin , Zhaohua Li
      Water scarcity and stress have attracted increasing attention as water has become increasingly regarded as one of the most critical resources in the world’s sustainable development. The Water Poverty Index (WPI), an interdisciplinary but straightforward measure that considers water availability from both the bio-geophysical perspective and the socio-economic perspective of people’s capacity to access water, has been successfully applied at national, regional, and local levels around the world. However, the general assessment of water stress at a macro level over only a snapshot limits the understanding of the geographic differences in and dynamics of water stress; this will, in turn, mislead decision-makers and may result in improper water strategies being implemented. In addition, to date, the typologies and trajectories of water stress have been underexplored. To fill this knowledge gap, we examine the spatio-temporal patterns, trajectories, and typologies of water stress using an adapted WPI for six counties in Zhangye City, which lies within an arid region of China, in order to provide policy priorities for each county. The results of our assessment indicate that water stress has become more severe over time (2005–2011) in most of the counties in Zhangye City. The results also show a distinct spatial variation in water scarcity and stress. Specifically, the results for Shandan county reflect its progressive policies on water access and management, and this county is regarded as engaging in good water governance. In contrast, Ganzhou district has faced more severe water pressure and is regarded as practicing poor water governance. Typology results show that each county faces its own particular challenges and opportunities in the context of water scarcity and stress. In addition, the trajectory map reveals that none of the counties has shown substantial improvement in both water access and management, a finding that should draw decision-makers’ close attention.

      PubDate: 2015-03-10T08:35:25Z
  • Discrimination of crop types with TerraSAR-X-derived information
    • Abstract: Publication date: Available online 13 November 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Rei Sonobe , Hiroshi Tani , Xiufeng Wang , Nobuyuki Kobayashi , Hideki Shimamura
      Although classification maps are required for management and for the estimation of agricultural disaster compensation, those techniques have yet to be established. This paper describes the comparison of three different classification algorithms for mapping crops in Hokkaido, Japan, using TerraSAR-X (including TanDEM-X) dual-polarimetric data. In the study area, beans, beets, grasslands, maize, potatoes and winter wheat were cultivated. In this study, classification using TerraSAR-X-derived information was performed. Coherence values, polarimetric parameters and gamma nought values were also obtained and evaluated regarding their usefulness in crop classification. Accurate classification may be possible with currently existing supervised learning models. A comparison between the classification and regression tree (CART), support vector machine (SVM) and random forests (RF) algorithms was performed. Even though J–M distances were lower than 1.0 on all TerraSAR-X acquisition days, good results were achieved (e.g., separability between winter wheat and grass) due to the characteristics of the machine learning algorithm. It was found that SVM performed best, achieving an overall accuracy of 95.0% based on the polarimetric parameters and gamma nought values for HH and VV polarizations. The misclassified fields were less than 100a in area and 79.5–96.3% were less than 200a with the exception of grassland. When some feature such as a road or windbreak forest is present in the TerraSAR-X data, the ratio of its extent to that of the field is relatively higher for the smaller fields, which leads to misclassifications.

      PubDate: 2015-03-10T08:35:25Z
  • Comprehensive hydrologic calibration of SWAT and water balance analysis in
           mountainous watersheds in northwest China
    • Abstract: Publication date: Available online 2 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Zhixiang Lu , Songbing Zou , Honglang Xiao , Chunmiao Zheng , Zhenliang Yin , Weihua Wang
      Model calibration is important for streamflow simulations using distributed hydrological models, especially in highland and cold areas of northwest China with scarce data. Quantitative analysis of water balance based on the accurate simulation is also essential for reasonably planning and managing water resources in these river basins facing a severe water shortage. In this study, a comprehensive method was proposed to calibrate the Soil and Water Assessment Tool (SWAT) model in the Yingluoxia watershed, upstream area of the Heihe River basin; it was based on multi-temporal, multi-variable and multi-site integrated drainage characteristics. Meanwhile a fresh approach of the parameter transferability and model validation was used by applying the set of calibrated parameters in its tributary to other area of the watershed. The results indicated that the method was effective and feasible; the values of Nash–Sutcliffe Efficiency (NSE) and Coefficient of Determination (r 2) were greater than 0.81 and as high as 0.94 and the absolute values of the Percent Bias (PBIAS) were less than 2. Based the output of model the water balance in the Yingluoxia watershed was analyzed, that the mean annual precipitation, evapotranspiration, and discharge of the watershed from 1990 to 2000 were 491.8mm, 334mm, and 157.8mm, respectively. The comprehensive calibration method based on multi-temporal, multi-variable and multi-site integrated drainage characteristics can better portray the hydrological processes of watershed and improve the model simulation; and the output of the model then provide a reliable reference for assessing and managing water resource of the watershed.

      PubDate: 2015-03-10T08:35:25Z
  • Modelling the influence of thermal discharge under wind on algae
    • Abstract: Publication date: Available online 2 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Le Feng , Bin Chen , Tasawar Hayat , Ahmed Alsaedi , Bashir Ahmad
      Wind-driven processes exert an important impact on aquatic ecosystems, especially on shallow reservoirs. Flow and heat transport under wind in the Douhe reservoir in China were simulated by a two-dimensional mathematical model. Areas corresponding to different temperature rises were calculated for different wind speed conditions with high frequency. It is shown that high temperature rise areas increase for maximum wind speed conditions while low temperature rise areas keep constant for various wind speed conditions. The concentration of Chl.a decreases with the increase of wind speed, indicating that low wind speed is suitable for algae blooming in the Douhe reservoir. The effects of wind on Bacillariophyta biomass growth become more obvious with the increase of temperature rise areas. The influenced areas of lower temperature rise (0.2–1.49°C) and higher temperature rise (1.5–2°C) zone are 8.57×106 m2 and 5.18×106 m2, respectively, and corresponding total variation amounts of Bacillariophyta biomass are 2.24×105/m2 and 0.42×105/m2, respectively. Results show that wind has a significant impact on ecological effects due to thermal discharge from thermal power plant into shallow reservoirs.

      PubDate: 2015-03-10T08:35:25Z
  • Multilevel modeling of NPP change and impacts of water resources in the
           Lower Heihe River Basin
    • Abstract: Publication date: Available online 2 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Haiming Yan , Jinyan Zhan , Qun’ou Jiang , Yongwei Yuan , Zhihui Li
      Net primary productivity (NPP) lays the foundation for provision of various ecosystem services, and understanding the impacts of potential influencing factors on NPP is of great significance to formulating appropriate management measures to guarantee the sustainable provision of essential ecosystem services. This study analyzed the impacts of potential influencing factors on NPP in the lower Heihe River Basin, a typical arid and semi-arid region in China. First, NPP was estimated with the C-FIX model, and then the multilevel model was used to analyze the impacts of potential influencing factors on NPP during 2000–2008. Finally decomposition analysis was used to further analyze the contribution of influencing factors to NPP change during 2000–2008. The average NPP increased by approximately 9.07% during 2000–2008, and results of the multilevel model indicate that both the socioeconomic variables and demographic variables are useful in explaining NPP change. In particular, coefficients of rainfall and evapotranspiration which represent the water availability reached 0.0456 and 0.2956, respectively. Results of decomposition analysis suggested that the water availability played an important role in increasing NPP, with a contribution rate of 44.17%, and it is necessary to carry out some policies that can promote the water use efficiency to increase NPP under the background of climate change and intensified human activities. There are some uncertainties in the results of this study, but these results still can provide valuable reference information for the water resource management to increase the ecosystem service supply in the lower Heihe River Basin.

      PubDate: 2015-03-10T08:35:25Z
  • Two-scale analysis for environmental dispersion in a two-layer wetland
    • Abstract: Publication date: Available online 2 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Bin Chen , Lizhu Zhang , Tasawar Hayat , Ahmed Alsaedi , Bashir Ahmad
      Studies on environmental dispersion are essential for applications as water management. The two-scale perturbation analysis is applied in this paper to deduce the environmental dispersion model for the typical case of contaminant transport in two-layer wetland flows. The analysis follows the established theoretical framework on the basis of phase average and the concept of Taylor dispersion. By the obtained flow velocity distribution for the two-layer flow, the analytical expression for the environmental dispersivity is deduced and shown to be consistent with previous results by the concentration moment method, while with much simplifications on the expression for ignoring the less concerned time-dependent stage of the dispersivity.

      PubDate: 2015-03-10T08:35:25Z
  • Impact of land-use induced changes on agricultural productivity in the
           Huang-Huai-Hai River Basin
    • Abstract: Publication date: Available online 24 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Gui Jin , Zhaohua Li , Zhan Wang , Xi Chu , Zhihui Li
      The water resource allocation is greatly influenced by the land use, agricultural productivity and farmers’ income. Therefore analyzing the impacts of land use changes on agricultural productivity and subsequent effects on farmer’s income is an important basis of the further study on the management mechanism and optimal water resource allocation. Taking the Huang-Huai-Hai River Basin as the study area, this study examined the impacts of conversion from cultivated land to built-up land from 2000–2005 and 2005–2008. Then the agricultural productivity was estimated with the Estimation System for Agricultural Productivity model, and the changes in agricultural productivity caused by land conversion were analyzed. Thereafter, Simultaneous Equations Model was used to analyze the impacts of the conversion from cultivated land to built-up land on the agricultural productivity and subsequent effects on farmer’s income. The results showed that: (1) The agricultural productivity was stable during the whole period, reaching about 2.84ton/ha, 3.09ton/ha and 2.80ton/ha on average in 2000, 2005 and 2008, respectively, but the conversion from cultivated land to built-up land had important influence on the spatial pattern of agricultural productivity. (2) The land productivity, total power of agricultural machinery and the conversion from cultivated land to built-up land had an overall positive effect on the agricultural productivity. (3) The agricultural productivity and gross domestic product had positive influence on the farmers’ income, while the cultivated land area per capita and percentage of farming employee had negative influence, indicating that the farmer’s income was mainly contributed by non-agricultural income. These results in this study showed that optimal land use management can play an important role in promoting virtuous ecosystem cycle and sustainable socioeconomic development, which can also lay an important foundation for further research on the optimal allocation of water resources in the Huang-Huai-Hai River Basin.

      PubDate: 2015-03-10T08:35:25Z
  • Predicting streamflow for land cover changes in the Upper Gilgel Abay
           River Basin, Ethiopia: A TOPMODEL based approach
    • Abstract: Publication date: Available online 10 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): W. Gumindoga , T.H.M. Rientjes , A.T. Haile , T. Dube
      Hydrological effects of land cover changes and runoff contributions from respective land cover types are analysed for the Upper Gilgel Abay basin in Ethiopia. Runoff production and streamflow are simulated by the TOPMODEL approach. For impact assessment of land cover changes, satellite based land covers for the years 1973, 1986 and 2001 are considered. Catchment topography as well as land cover and vegetation characteristics are derived from satellite images and serve to estimate model parameters. Land cover in TOPMODEL has been implemented by spatial units based on the actual size of each land cover type. The topographic index distribution function, which is an important input to the TOPMODEL, is prepared for each land cover type. Simulations are also performed for specific land cover types to allow inter comparison of hydrological responses. Results showed that the highest peak flow as well as the annual streamflow volume varied among the land cover types agriculture, forest and grassland which dominate land cover in the catchment. Results of this study show that in data poor basins, satellite images provide suitable land surface data for rainfall–runoff modelling and land surface parameterization. Findings are of relevance for many African rural catchments which experience rapid population increases and resource scarcity.

      PubDate: 2015-03-10T08:35:25Z
  • Inferring land surface parameters from the diurnal variability of
           microwave and infrared temperatures
    • Abstract: Publication date: Available online 27 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Hamidreza Norouzi , Marouane Temimi , Amir AghaKouchak , Marzieh Azarderakhsh , Reza Khanbilvardi , Gerarda Shields , Kibrewossen Tesfagiorgis
      This study investigates the properties of the diurnal cycle of microwave brightness temperatures (TB), namely the phase and the amplitude, and their variability in time and space over the globe to infer information on key land surface parameters like changes in soil texture spatial distribution, soil moisture conditions, and vegetation density. The phase corresponds to the lag between Land Surface Temperature (LST) and TB diurnal cycles. The amplitude is determined as the difference between the maximum and the minimum of TB diurnal cycle. The diurnal cycle of TB was constructed using observations from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and the Special Sensor Microwave/Imager (SSM/I). The latter offer a series of sensors, namely, F13, F14, and F15 that were used in this study for a higher temporal coverage and more accurate diurnal cycle determination. LST estimates, which are available every 3h from the International Satellite Cloud Climatology Project (ISCCP) database were used to build the LST diurnal cycle. ISCCP LST data is an infrared-based temperature with almost no penetration and is the representative of top skin temperature. The analyses of the diurnal cycles showed that the diurnal amplitude of TB decreases as the vegetation density increases, especially in the case of low frequencies which penetrate deeper into the canopy which makes them more sensitive to changes in vegetation density. The interannual variations of TB diurnal amplitudes were also in agreement with the seasonality of the vegetation cover. Over desert and rain forest regions where surface conditions do not vary significantly throughout the year, the changes in diurnal amplitudes were the lowest. A relationship between phase and amplitude values was established. It was found that the amplitude of TB diurnal cycle decreases when the phase lag increases. The spatial distribution of the determined diurnal properties, namely, phase and amplitude of TB, showed an agreement with lithology maps in desert areas. Lower TB amplitudes were observed over regions with loose siliceous rocks. Phase lag values between 1.5 and 3h corresponded to 83% of the class “loose siliceous rocks” in the Sahara Desert, which corroborates the potential of using the diurnal properties of TB as an indicator of land surface parameters.

      PubDate: 2015-03-10T08:35:25Z
  • Analysis of institutional mechanisms that support community response to
           impacts of floods in the middle-zambezi river basin, Zimbabwe
    • Abstract: Publication date: Available online 19 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): P. Muhonda , C. Mabiza , H. Makurira , K. Kujinga , I. Nhapi , J. Goldin , D.A. Mashauri
      In recent years, the frequency of occurrence of floods has increased in Southern Africa. An increase in the frequency of extreme events is partly attributed to climate change. Floods negatively impact on livelihoods, especially those classified as poor, mainly by reducing livelihood options and also contributing to reduced crop yields. In response to these climatic events, governments within Southern Africa have formulated policies which try to mitigate the impacts of floods. Floods can be deadly, often occurring at short notice, lasting for short periods, and causing widespread damage to infrastructure. This study analysed institutional mechanisms in Mbire District of Zimbabwe which aim at mitigating the impact of floods. The study used both quantitative (i.e. questionnaires) and qualitative (i.e. key informant interviews, focus group discussions and observations) data collection methods. Secondary data such as policy and legislation documents and operational manuals of organisations that support communities affected by disasters were reviewed. Qualitative data was analysed using the thematic approach and social network analysis using UCINET 6. Quantitative data were analysed using SPSS 19.0. The study found out that there exists institutional framework that has been developed at the national and local level to support communities in the study area in response to the impacts of floods. This is supported by various pieces of legislation that are housed in different government departments. However, the existing institutional framework does not effectively strengthen disaster management mechanisms at the local level. Lack of financial resources and appropriate training and skills to undertake flood management activities reduce the capacity of communities and disaster management organisations to effectively mitigate the impacts of floods. The study also found that there are inadequate hydro-meteorological stations to enable accurate forecasts. Even in those cases where forecasts predicting extreme weather events have been made, communities have difficulties accessing and interpreting such forecasts due to inadequate communication systems. Such factors reduce the preparedness of communities to deal with extreme weather events.

      PubDate: 2015-03-10T08:35:25Z
  • Evidence for tidal triggering on the earthquakes of the Hellenic Arc,
    • Abstract: Publication date: Available online 28 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): G. Vergos , D.N. Arabelos , M.E. Contadakis
      In this paper we investigate the tidal triggering evidence on the earthquakes of the seismic area of the Hellenic Arc using the Hist(ogram)Cum(mulation) method. We analyze the series of the earthquakes occurred in the area which is confined by the longitudes 22° and 28°E and latitudes 34° and 36°N in the time period from 1964 to 2012. In this time period 16,137 shallow and of intermediate depth earthquakes with ML up to 6.0 and 1,482 deep earthquakes with ML up to 6.2 occurred. The result of the this analysis indicate that the monthly variation of the frequencies of earthquake occurrence is in accordance with the period of the tidal lunar monthly variations, and the same happens with the corresponding daily variations of the frequencies of earthquake occurrence with the diurnal luni-solar (K1) and semidiurnal solar (S2) tidal variations. These results are in favor of a tidal triggering process on earthquakes when the stress in the focal area is near the critical level.

      PubDate: 2015-03-10T08:35:25Z
  • Impacts of small built infrastructure in inland valleys in Burkina Faso
           and Mali: Rationale for a systems approach that thinks beyond rice?
    • Abstract: Publication date: Available online 21 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Pamela Katic , Jonathan Lautze , Regassa E. Namara
      The potential to increase agricultural production in inland valleys in West Africa has received a good degree of attention in both national development strategies and academic literature, and improving agriculture productivity in inland valleys has been an active area of donor engagement. Despite this attention, documentation of the degree to which benefits are enhanced through construction of built water storage infrastructure in such sites is somewhat scant. This paper examines evidence from eight inland valley sites with recently-built water retention infrastructure (4 in southwest Burkina Faso, 4 in southeast Mali) to determine how economic returns derived from agricultural production have changed through built infrastructure construction. Farmer interviews were undertaken at each site to identify costs and benefits of agricultural production before and after small built infrastructure construction. Overall results indicate that net present value increased substantially after built infrastructure was constructed. The results nonetheless highlight substantial variation in economic impacts across sites. A central variable explaining such variation appears to be the degree to which water retention is exploited for groundwater-based offseason cultivation. These findings will help development planners to better predict the degree and nature of change engendered by water storage projects in inland valley sites, and help to ground-truth grand statements about the development potential of this piece of natural infrastructure.

      PubDate: 2015-03-10T08:35:25Z
  • Impacts of land use and land cover changes on surface energy and water
           balance in the Heihe River Basin of China, 2000–2010
    • Abstract: Publication date: Available online 24 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xiangzheng Deng , Qingling Shi , Qian Zhang , Chenchen Shi , Fang Yin
      It is well known that there are huge land use and land cover changes (LUCC) all over the world in recent decades, and plenty of ensuing effect appeared on the energy and water balance. This study aims to analyze the impacts of land use and land cover changes on the energy and water balance in the Heihe River Basin of China during 2000–2010, and four key study sites with representative hydrological stations and dramatic LUCC in the past decades were selected to illustrate the responses of the energy and water balance to LUCC. First, LUCC of the Heihe River Basin from 2000 to 2010 was analyzed based on the interpretation of remote sensing images. Then a series of indicators of the energy and water balances were simulated with the Weather Research and Forecasting (WRF) model and corresponding land use and land cover data. Thereafter the impacts of LUCC on the surface energy and water balance were detected and analyzed. The spatial–temporal variance of the impacts of LUCC on energy and water balance in a typical arid inland river basin was specifically presented in following analysis. The results show that different land use/cover conversions result in various energy balances. During this process, the most significant impacts on surface energy balance occurred when grassland was converted to barren or sparsely vegetated land. As for water balance, the impact is measured with variations of precipitation, runoff and evapotranspiration induced by LUCC, which were also remarkable, although seasonal trends of the effects are similar among various land use/cover conversions during 2000–2010. At last, policy suggestions, e.g., shifting the water balance by LUCC to improve the water management, are given to conclude this study.

      PubDate: 2015-03-10T08:35:25Z
  • Rejection of pharmaceuticals by nanofiltration (NF) membranes: Effect of
           fouling on rejection behaviour
    • Abstract: Publication date: Available online 28 January 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): T.O. Mahlangu , T.A.M. Msagati , E.M.V. Hoek , A.R.D. Verliefde , B.B. Mamba
      The aim of this study was to investigate the effects of membrane fouling by sodium alginate, latex and a combination of alginate+latex on the rejection behaviour of salts and organics. Sodium chloride and caffeine were selected to represent salts and organics, respectively. The effects of the presence of calcium chloride on the fouling behaviour and rejection of solutes were investigated. The results revealed that the salt rejection by virgin membranes was 47% while that of caffeine was 85%. Fouling by alginate, latex and combined alginate–latex resulted in flux decline of 25%, 37% and 17%, respectively. The addition of Ca2+ aggravated fouling and resulted in further flux decline to 37%. Fouling decreased salt rejection, an observation that was further aggravated by the addition on Ca2+. However, it was also observed that fouling with alginate and calcium and with latex and calcium minimised salt rejection by 30% and 31%, respectively. This reduction in salt rejection was attributed to the decrease in permeate flux (since rejection is a function of flux). There was a slight increase in caffeine rejection when the membrane was fouled with latex particles. Moreover, the presence of foulants on the membrane resulted in a decrease in the surface charge of the membrane. The results of this study have shown that the NF 270 membrane can be used to treat water samples contaminated with caffeine and other organic compounds that have physicochemical properties similar to those of caffeine.

      PubDate: 2015-03-10T08:35:25Z
  • Application of hydrogeochemical modelling in simulating the transportation
           of elements in fly ash heap under different disposal systems in South
    • Abstract: Publication date: Available online 4 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J.M. Mbugua , J.C. Ngila , A. Kindness , M. Demlie
      Ash heap modelling of South African fly ash from Tutuka was carried out and the duration of transportation projected for 20years based on two disposal scenarios, namely; irrigation of ash with rainwater, and irrigation with brines. The hydrogeochemical modeling code, PHREEQC, was applied in the study which gave insights into the speciation, release and transport of elements from the water and brines–fly ash long term interactions. Tutuka ash–water heap model showed a general sharp decrease of total elemental concentrations released during the first 2.5years simulation as the pH value dropped from 12.6 to 8.7, after which it remained constant and their concentration remained constant up to 20years. The elements showing this trend included Ca, Mg, Al, Fe, Sr, Zn, Na, K, Li and C(4). Generally, brines caused sharp increase in released concentration of the elements Ca, Mg, S(6) and C(4) for the first 3years of heap irrigation whereas with water irrigation an opposite trend was observed in which the elemental concentrations decreased. Much of the release chemistry of the elements was closely related to the phase dissolution/precipitation and formation as the major controlling factors. Generally therefore, the modelled leachate quality results revealed that many elements are mobile and move through the ash heap in a progressive leaching pathway. The model could therefore be used to provide reasonable leachate quality from the modelled Tutuka ash heap which may be reaching the ground water. Overall, the ash heap modelling enhanced the understanding of the environmental impacts of ash–water–brines interactions and demonstrated that leachate composition is determined by the following factors; (i) the mass flows from the pores of fly ash, (ii) the surface dissolution of the mineral phases, (iii) the various chemical reactions involved during the ash–brine and ash–water interactions, (iv) the interactions with a gas phase (atmospheric CO2), (v) the composition of the initial fly ash, and (vi) the leachate flow and hydrodynamics as captured in the conceptual model. Further model validation is recommended with lysimeters to quantatively compare the simulated results against the experimental data and improve on the model.

      PubDate: 2015-03-10T08:35:25Z
  • An empirical study on the spatial distribution of the population, economy
           and water resources in Northeast China
    • Abstract: Publication date: Available online 7 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Conglin Zhang , Yu Liu , Haijuan Qiao
      The relationship among the population, economy and water resources is complex, and the contradictions and conflicts will appear and aggravate with the rapid development of economy and society in Northeast China. Based on the statistical analysis of the available data, this paper depicted the static distribution characteristics of the population, economy and water resources of Northeast China in 2011. It was found that the spatial distribution of the population, economy and water resources was unbalanced in Northeast China. The water resources mismatched with the population and economy. The population and economy were relatively dense and developed in the southwestern part of Northeast China respectively, while the water resources was relatively scarce. However, the situations in the northern part of Northeast China were opposite to those in the southwestern part. The population-economy inconsistence indexes of the cities in northern part of Northeast China showed a significant trend of spatial aggregation and heterogeneity. The cities with lower (<1.5) and higher (>1) inconsistence indexes all faced the problem of water resources shortage. Applying geometric gravity center method and grey correlation model, the result indicated that there was relatively high spatial relevance and the relative deviation among the spatial dynamic distributions of the population, economy and water resources was large. The gravity centers of economy and per capita average annual total water resources moved westward, while the gravity center of population gravity center moved eastward in the period of 1997–2011 in Northeast China. It must be noted that, the migration trend of the economy gravity center was more significant than those of the population and water resources.

      PubDate: 2015-03-10T08:35:25Z
  • Hand dug wells in Namibia: An underestimated water source or a threat to
           human health?
    • Abstract: Publication date: Available online 7 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): H. Wanke , A. Nakwafila , J.T. Hamutoko , C. Lohe , F. Neumbo , I. Petrus , A. David , H. Beukes , N. Masule , M. Quinger
      The rural population of parts of northern and western Namibia uses hand dug wells for their domestic water supply, partly because no other source (e.g., deep tube wells) is available, but also as a substitute for pipeline water that is often perceived as being too expensive. The water quality of these wells is usually not monitored or controlled, thus a study has been carried out in four study areas in Namibia: southern Omusati/Oshana area, Okongo/Ohangwena area, Omatjete/Omaruru area, Okanguati/Kunene area. Hand dug wells have been tested for on-site parameters: electric conductivity, pH and temperature while samples were taken for major inorganic constituents and several minor and trace constituents including fluoride and nitrate. In addition a sampling campaign in 2010 included the determination of coliform bacteria and Escherichia coli. Results were classified according to the Namibian Water Guidelines. The constituents making the water unfit for human consumption are fluoride, nitrate, sulphate and total dissolved solids. Contamination by E. coli was indicated in nearly all wells that are used for livestock watering. For the Omatjete/Omaruru study area an isotope based study on the source of nitrate has indicated manure as a source. The range of recharge values obtained for the studied villages ranges from 1mm/a to locally more than 100mm/a. Overall the water resource in the shallow perched aquifers in the study areas is in many places inappropriate for human consumption. Treatment to improve the quality or introduction of protection measures is necessary to bring this resource to an acceptable quality according to national and/or international standards.

      PubDate: 2015-03-10T08:35:25Z
  • Integrating TRMM and MODIS satellite with socio-economic vulnerability for
           monitoring drought risk over a tropical region of India
    • Abstract: Publication date: Available online 19 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Aradhana Yaduvanshi , Prashant K. Srivastava , A.C. Pandey
      Drought is a recurring feature of the climate, responsible for social and economic losses in India. In the present work, attempts were made to estimate the drought hazard and risk using spatial and temporal datasets of Tropical Rainfall Measuring Mission (TRMM) and Moderate Resolution Imaging Spectroradiometer (MODIS) in integration with socio-economic vulnerability. The TRMM rainfall was taken into account for trend analysis and Standardized Precipitation Index (SPI) estimation, with aim to investigate the changes in rainfall and deducing its pattern over the area. The SPI and average rainfall data derived from TRMM were interpolated to obtain the spatial and temporal pattern over the entire South Bihar of India, while the MODIS datasets were used to derive the Normalized Difference Vegetation Index (NDVI) deviation in the area. The Geographical Information System (GIS) is taken into account to integrate the drought vulnerability and hazard, in order to estimate the drought risk over entire South Bihar. The results indicated that approximately 36.90% area is facing high to very high drought risk over north-eastern and western part of South Bihar and need conservation measurements to combat this disaster.

      PubDate: 2015-03-10T08:35:25Z
  • On diurnal dependence and spatial scales of seismo-ionospheric effects in
           the E-layer
    • Abstract: Publication date: Available online 19 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): E.V. Liperovskaya , C.-V. Meister , D.H.H. Hoffmann , A.S. Silina
      In the present work, disturbances of the f b E s -frequency of the sporadic E-layer of the ionosphere are investigated in connection with earthquakes. The f b E s -frequency is proportional to the square root of the maximum ionisation density of the sporadic E-layer. In this work, it is shown that two days before a seismic shock with magnitude M > 5.5 , and during the shock, an increase of the f b E s -frequency is obtained around midnight at distances from the epicenter R < exp M + 100 km in the case that the focus of the shock was situated at depths smaller than 60 km. Data obtained by the three ionospheric sounding stations “Kokubunji”, “Akita” and “Yamagawa” are analysed, which were recorded during a total time of 42 years. The superimposed epoches method is applied for a few tens of earthquakes.

      PubDate: 2015-03-10T08:35:25Z
  • Seismo-meteo-electromagnetic phenomena observed during a 5-year interval
           around the 2011 Tohoku earthquake
    • Abstract: Publication date: Available online 19 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Alexander Schekotov , Masashi Hayakawa
      The purpose of the paper is to try to find ULF electromagnetic precursors to the 2011 Tohoku earthquake (EQ), on the basis of extensive investigation of radiations in vertical component of the magnetic field or with a large ratio of the vertical to full horizontal component. Nighttime records have been analyzed of three Japanese fluxgate magnetometers located in a distance from 300 to 1300km from the epicenter of the main shock, and the frequency range from 10 to 150mHz was used for the analysis. We have applied wavelet analyses to improve the detection of pulsed signals. All obtained scalograms have been averaged over the nighttime interval from 01h to 05h JST and flattened by means of multiplication by square of frequency. The sequence of spectra thus obtained has been compared with the evolution of seismicity, which has resulted in that the radiation in the vertical component has been detected. It exhibits seasonal variations with winter maxima, but it increases further by approaching the moment of the EQ and decreases after that. This radiation seems to be correlated with atmospheric parameters – air humidity, temperature, vapor pressure and rainfall. So, we consider that this radiation cannot be caused by subsurface sources, but its possible sources can be atmospheric discharges. The evolution of this phenomenon can be explained by a seasonal variation of atmospheric parameters and also its variations under the influence of injection of gas from the focal zone of a forthcoming EQ.

      PubDate: 2015-03-10T08:35:25Z
  • VLF/LF signal studies of the ionospheric response to strong seismic
           activity in the Far Eastern region combining the DEMETER and ground-based
    • Abstract: Publication date: Available online 21 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A. Rozhnoi , M. Solovieva , M. Parrot , M. Hayakawa , P.-F. Biagi , K. Schwingenschuh , V. Fedun
      The paper presents the results of a joint analysis of ground-based and satellite observations of very low-frequency and low-frequency (VLF/LF) signals during periods of strong seismic activity in the region of Kuril Islands and Japan in 2004–2010. Ground and satellite data was processed using a method based on the difference between the real signal in nighttime and that of a model. The results of the analysis show a good correlation between ground-based and satellite data for several cases of strong (M ⩾6.8) earthquakes.

      PubDate: 2015-03-10T08:35:25Z
  • Time-Frequency analysis of VLF for seismic-ionospheric precursor
           detection: Evaluation of Zhao-Atlas-Marks and Hilbert-Huang Transforms
    • Abstract: Publication date: Available online 21 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): C. Skeberis , Z.D. Zaharis , T.D. Xenos , S. Spatalas , D.N. Arabelos , M.E. Contadakis
      This work investigates the application of two post-processing methods of extracting spectra from VLF signals in order to detect disturbances that could be attributed to seismic-ionospheric precursory phenomena. Although precursory phenomena have been investigated in detail in past studies, a different application of time-frequency analysis methods may produce distinct patterns, which reveal disturbances in the VLF spectra received from stations that are in the propagation path over preparation zones, and also pinpoint disturbances that could be attributed to seismic-ionospheric precursors. To this purpose, three different methods of post processing are compared. These are the Wavelet Transform as a benchmark method in the form of the Continuous Wavelet Transform, a noise-assisted variant of the Hilbert-Huang Transform and the Zhao-Atlas-Marks Distribution. Comparative diagrams are presented and the advantages and weaknesses of each method are presented.

      PubDate: 2015-03-10T08:35:25Z
  • Simulated water productivity in Gansu Province, China
    • Abstract: Publication date: Available online 24 February 2015
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Jinyan Zhan , Zhongxiao Sun , Zhan Wang , Jiancheng Chen , Zhaohua Li
      Economic value of water and economic analysis of water use management in Gansu Province of China have attracted widespread public attention. With the socioeconomic development, research on water resources has become more important than before. In this study, we define “water productivity” as the changes of economic production outputs of sectoral activities in every cubic meter of water input, which is also the technical coefficient of water resource use in each sector. According to Computable General Equilibrium (CGE) framework, based on the Input–Output Table 2007 and water resources bulletin of Gansu Province, we introduced the water into the ORANI-G (A Generic Single-Country Computable General Equilibrium model) model through the nested constant elasticity of substitution (CES) production function to analyze the changes of economic productions caused by water supply changes. We then examined water productivity in different sectors. Empirical results showed that current water productivity is underestimated. Agricultural water productivity is lower than that of the secondary and tertiary industries, even although agricultural water use is the largest part of water use in Gansu Province, and therefore improving agricultural water productivity can greatly mitigate the water shortage. Simulation results indicate that industrial transformation and development of water-saving industries will also mitigate water scarcity. Moreover, sensitivity analysis shows that the empirical results are robust under different scenarios. The results also show that higher constant elasticity of substitution rate (CES) between water and other production factors will contribute to sustainable development.

      PubDate: 2015-03-10T08:35:25Z
  • Sustainability of donor-funded rural water supply and sanitation projects
           in Mbire district, Zimbabwe
    • Abstract: Publication date: Available online 31 October 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Johnson Kwangware , Aloyce Mayo , Zvikomborero Hoko
      The sustainability of donor-funded rural water supply and sanitation projects was assessed in Mbire district, Zimbabwe in terms of level of community participation, quality of implementation and reliability of the systems. The study was carried out through questionnaires, focus group discussions, interviews and field observations. The results show that the quality of implementation of the projects was deemed to be good and participation of the communities in project ideas initiation and choice of technology was found to be very low. Reliability of the systems was found to be very high with 97% of the boreholes in all the three wards studied being functional. Financial management mechanisms were very poor because water consumers were not willing to pay for operation and maintenance. The projects were classified as potentially sustainable with sustainability index between 5.00 and 6.67. Poor financial management mechanisms for effective borehole maintenance, poor quality of construction and lack of community participation in project planning were found to be potential threats to the sustainability of the projects. Future projects should establish the need for the service and should thus be demand driven to ensure effective participation of the water consumers and enhance project’s potential for sustainability.

      PubDate: 2015-03-10T08:35:25Z
  • Identifying the potential for irrigation development in Mozambique:
           Capitalizing on the drivers behind farmer-led irrigation expansion
    • Abstract: Publication date: Available online 30 October 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): W. Beekman , G.J. Veldwisch , A. Bolding
      Smallholder irrigation in Central Mozambique predominantly takes place in an informal setting. This renders these smallholders and their activities invisible for policy purposes. Identification efforts of smallholder irrigation as well as the potential for new irrigation development are often the basis for policy setting. But the potential is often approached technocratically: the technical availability of water and land with the assumption that smallholder irrigation is not happening and should be developed. Although more and more effort is done to include social economical aspects into the identification as well, it remains a GIS exercise, based on incomplete data using large pixel sizes, analyzing countries or continents as a whole. This study describes and presents the methodology and the results of an irrigation potential identification exercise carried out in two studies in Central Mozambique. Apart from describing the identification methods used, this study highlights the extent of farmer-led irrigation development, its drivers and the potential for farmer-led smallholder irrigation development. This study demonstrates the prolific nature of smallholder irrigation, arguing for the recognition that smallholder farmers are already developing irrigation and that this should lead to changing the focus of identification efforts towards the drivers behind farmer-led irrigation development. Using these context-specific drivers to define the potential for new irrigation development should result in a better response in policy to both the technical and socio-economical potential of smallholder irrigation development.

      PubDate: 2015-03-10T08:35:25Z
  • Baseflow prediction in a data-scarce catchment with Inselberg topography,
           Central Mozambique
    • Abstract: Publication date: Available online 13 October 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): H. Weemstra , A.L. Oord , F.S. de Boer , P.W. Beekman
      This study aimed to improve the understanding of hydrological processes in a humid (sub)tropical area in Africa with Inselberg topography. Additionally, the study intended to develop an approach for selective discharge data acquisition to determine water availability for smallholder irrigation in similar data-scarce catchments. During the December 2012–August 2013 field campaign meteorological and river stage data were collected at the Messica catchment in Central Mozambique. The 220km2 catchment has an estimated 1000ha of irrigated land, developed by smallholder farmers. Baseflow in the perennial tributary streams on the slopes of a meta-sedimentary Inselberg is the source of irrigation water. The baseflow recession curve of one of these tributaries is analysed and the water balance of an average year was determined. Precipitation, potential evapotranspiration, actual evapotranspiration and discharge were estimated to be 1224, 1462, 949 and 266mm/year respectively. Differential gauging showed that the perennial tributaries gain water; the groundwater contribution increased with approximately 50% over two and a half month relative to the downstream discharge from March to May. In the downstream parts the groundwater contribution per metre stream length is between 30% and 100% higher compared to the upstream parts for two of the tributaries. Nevertheless, due to natural streambed infiltration and irrigation canals, discharge varies over the length of these tributaries. A rainfall–runoff model (HBV) was calibrated using the field data to examine the relation between precipitation characteristics and discharge at the start of the dry season. For precipitation scenarios with low and high intensity precipitation, discharges from June onwards were approximately similar in size according to the calibrated model. This suggest that discharge at the start of the dry season is mainly determined by total precipitation and the timing of precipitation (i.e. early or late in the wet season), not by individual rainfall events or rainfall intensity. It is concluded that the use of selective discharge measurements and low frequency precipitation measurements can effectively be used for water availability assessments in Inselberg catchments. Further research should be conducted to verify the validity of the used techniques in other humid sub-tropical Inselberg areas.

      PubDate: 2015-03-10T08:35:25Z
  • Synthesis and application of reduced graphene oxide and molecularly
           imprinted polymers composite in chemo sensor for trichloroacetic acid
           detection in aqueous solution
    • Abstract: Publication date: Available online 8 October 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Rose W. Kibechu , Messai A. Mamo , Titus A.M. Msagati , S. Sampath , Bhekie B. Mamba
      This work presents the fabrication of a simple, cheap and fast thin film chemo sensor for detection of trichloroacetic acid (TCAA) in aqueous solutions. Reduced graphene oxide (RGO) based molecular imprinted polymers (MIP) chemo-sensor has been developed. The recognition of TCAA was achieved by imprinted polymers synthesized by copolymerization of 4-vinylpyridine (4-VP) and a crosslinking monomer ethylene glycol dimethacrylate (EDGMA) in acetonitrile using bulk polymerization method. Adsorption studies to determine the rebinding properties of the MIP with the template were conducted using UV Visible spectrophotometer. The fabricated sensor exhibited high recognition ability and affinity for HAA in comparison with the non-imprinted one which was employed as a control, this indicated that the MIP could selectively rebind with TCAA. Reduced graphene oxide (RGO) was used to improve conductivity of the sensor; RGO was obtained from reduction of graphene oxide (GO) synthesized using modified Stauddmer and Hummers method. Polysulphone was used in solution blending of MIP and RGO to form a hybrid which was deposited between two gold plated electrodes by spin coating to form a thin film. The performance of the imprinted sensor was studied using a homemade circuit. The results demonstrate that the sensor based on TCAA-imprinted polymer is fast, cheap and sensitive screening method of TCAA in drinking water.

      PubDate: 2015-03-10T08:35:25Z
  • Streamflow variation due to glacier melting and climate change in upstream
           Heihe River Basin, Northwest China
    • Abstract: Publication date: Available online 18 September 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Feng Wu , Jinyan Zhan , Zhan Wang , Qian Zhang
      Streamflow simulation is often challenging in mountainous watersheds because of incomplete hydrological models, irregular topography, immeasurable snowpack or glacier, and low data resolution. In this study, a semi-distributed conceptual hydrological model (SWAT-Soil Water Assessment Tool) coupled with a glacier melting algorithm was applied to investigate the sensitivity of streamflow to climatic and glacial changes in the upstream Heihe River Basin. The glacier mass balance was calculated at daily time-step using a distributed temperature-index melting and accumulation algorithm embedded in the SWAT model. Specifically, the model was calibrated and validated using daily streamflow data measured at Yingluoxia Hydrological Station and decadal ice volume changes derived from survey maps and remote sensing images between 1960 and 2010. This study highlights the effects of glacier melting on streamflow and their future changes in the mountainous watersheds. We simulate the contribution of glacier melting to streamflow change under different scenarios of climate changes in terms of temperature and precipitation dynamics. The rising temperature positively contributed to streamflow due to the increase of snowmelt and glacier melting. The rising precipitation directly contributes to streamflow and it contributed more to streamflow than the rising temperature. The results show that glacial meltwater has contributed about 3.25billionm3 to streamflow during 1960–2010. However, the depth of runoff within the watershed increased by about 2.3mm due to the release of water from glacial storage to supply the intensified evapotranspiration and infiltration. The simulation results indicate that the glacier made about 8.9% contribution to streamflow in 2010. The research approach used in this study is feasible to estimate the glacial contribution to streamflow in other similar mountainous watersheds elsewhere.

      PubDate: 2015-03-10T08:35:25Z
  • Benchmarking land use change impacts on direct runoff in ungauged urban
    • Abstract: Publication date: Available online 14 August 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Hasan Ozdemir , Emre Elbaşı
      This paper describes the results of benchmark testing of land use change impact on direct runoff using Soil Conservation Service-Curve Number (SCS-CN) model in two ungauged neighbouring urban watersheds (Çınar and Kadıyakuplu) in Istanbul, Turkey. To examine this impact, the model was applied to daily rainfall data using three different dated (1982, 1996 and 2012) hydrological soil groups and land use of the two ungauged urban watersheds. Finally, the impact of land use change and model performance were evaluated with the rainfall-runoff regression, the coefficient of determination and the NSE test using benchmark runoff data based on 1982 land use conditions. The results of the analysis indicate that the changing of land use types from natural surfaces to impervious surfaces has a significant impact on surface runoff. Additionally, remarkable spatial variations of the land use changes and their impact on the runoff in 1996 and 2012 were more detected in the Çınar watershed compared with the Kadıyakuplu watershed. The planning decision on land use of the watersheds, has vital role in these differences. The results of this research also reveal that change to intensive land use in urban watersheds has a significantly larger impact on runoff generation than those rainfall.

      PubDate: 2015-03-10T08:35:25Z
  • Streamflow forecasting for operational water management in the Incomati
           River Basin, Southern Africa
    • Abstract: Publication date: 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volumes 72–75
      Author(s): R.K.M. Sunday , I. Masih , M. Werner , P. van der Zaag
      If the future availability of water is uncertain to water managers, dam operators and water users, then an effective allocation among competing uses can be difficult. The difficulties can partly be alleviated by including streamflow forecasting as a tool for informed decision making. The Incomati basin in Southern Africa frequently experiences water shortages, and here streamflow forecasting can contribute to an improved water management. This paper explores the skill of streamflow forecasting and its usefulness in decision making in the Incomati basin. The study applies correlation and regression methods to forecast streamflow, and standard verification scores to evaluate the skill of the forecasts. Suitable statistical forecasting techniques were analysed and tested. The data used for forecasting include Sea Surface Temperature (SST), El Niño Southern Oscillation (ENSO), rainfall and streamflow. Results show that there is some scope for streamflow forecasting that can support water management decision making in the basin. The rainfall and streamflow of the previous months and/or season can be used to predict the streamflow in the next month and/or season with reasonable to good results. Results obtained during low flow periods (May–September) were found to be better than those obtained for the high flow periods (October–April). However, inclusion of ENSO and/or SST as an explanatory variable enhanced forecast skill, particularly during high flow periods. Forecasts were conducted for streamflow being in the below normal, above normal or normal terciles, with the forecasts for the extremes found to have better skill than forecast for the streamflow being in the normal tercile. Forecasts for low flows demonstrated the best skills, with these being of most use to the allocation of the scarce water resources.

      PubDate: 2015-03-10T08:35:25Z
  • Analysis of water stable isotopes fingerprinting to inform conservation
           management: Lake Urema Wetland System, Mozambique
    • Abstract: Publication date: 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volumes 72–75
      Author(s): Franziska Steinbruch , Stephan M. Weise
      The present study focusses on the analysis of water stable isotopes to contribute to understanding the hydrology of the Lake Urema wetland system in central Mozambique towards conservation management. Lake Urema Wetland is located in the Gorongosa National Park at the southernmost extent of the East African Rift System and is situated entirely within the Urema catchment. Of particular concern to the park’s management is the understanding of hydrological processes as these may trigger transformations of ecosystems, habitat losses and wildlife migrations. Concerns over the Lake Urema wetland’s drying up and the trapping of sediments in the floodplain have been raised for some time by conservationists. Water samples were collected for stable water isotope analyses during the wet and the dry seasons for the period 2006–2010 from springs, boreholes, rivers, and Lake Urema. In addition monthly composite precipitation was collected at two rain gauges. The results show that Lake Urema is maintained throughout the dry season merely from water generated during the wet season. It receives water from wet season precipitation and the runoff generated from this precipitation. The water source areas of the lake are the Gorongosa Mountain and the Barue Basement geomorphological units. Consequently, the source of the sediments which have been trapped into the lake and the floodplain has to be identified in these two catchment areas and urgent action is required to rescue the lake. This water body constitutes a groundwater buffer system which supports a unique wetland landscape. The annual inundations’ processes leading to the recharge-drainage cycle in the floodplain are most sensitive to the deposition of sediments, changing hydraulic gradients, and reducing wet season inflows and increasing drainage rates.

      PubDate: 2015-03-10T08:35:25Z
  • A fingerprinting method for the identification of uranium sources in
           alluvial aquifers: An example from the Khan and Swakop Rivers, Namibia
    • Abstract: Publication date: 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volumes 72–75
      Author(s): J.T. Hamutoko , B.S. Mapani , R. Ellmies , A. Bittner , C. Kuells
      A fingerprinting method for identifying sources of uranium in shallow groundwater alluvial aquifers of the Khan and Swakop Rivers was established using 234U/238U ratios and 235U/238U ratios in the areas that drain the Rossing Uranium mine and the Langer Heinrich Uranium mine, in Namibia. In most groundwater aquifers that drain basement granitoids enriched in uranium the contribution of the total uranium in the shallow alluvial aquifers may be significant. Another source of uranium in shallow alluvial aquifers maybe from anthropogenic sources associated with mining activities as is the case in our study area. The distribution of radionuclides in water depend on various factors that influence their solubility and mobility and control their concentration in water such as pH, Eh, O2 and availability of ligands. The study identified a methodology that can fingerprint the two sources i.e., a natural source where 234U/238U ratios are above unity and a second one where this ratio is below unity implying that the source is anthropogenic. In the study area, 234U/238U activity ratio is above unity (1.3–1.7) and 235U/238U is 0.045±0.015 that both identify a natural source for all elevated uranium and other radionuclides in groundwater of the study area. The uranium values in groundwater exceed the WHO guideline value of 15μg/l and it increases in the lowest part of Swakop River; but there is no gradual or systematic change in uranium concentration thus indicating that concentration is related to local factors such as the geology and lithology of the aquifer material, Eh and pH for each borehole. The 238U decay series exhibits disequilibrium due to different fractionation processes that include decaying of radioactive elements and alpha recoiling.

      PubDate: 2015-03-10T08:35:25Z
  • A global and regional perspective of rainwater harvesting in sub-Saharan
           Africa’s rainfed farming systems
    • Abstract: Publication date: 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volumes 72–75
      Author(s): Timothy Karpouzoglou , Jennie Barron
      In semi-arid and sub-humid sub-Saharan Africa highly variable rainfall, frequent droughts and low water productivity are consistently undermining food security. Rainwater harvesting technologies (RWHTs) help utilise water more productively whilst raising yield levels. In this article it is argued that realising the potential of RWHTs for resilience building and climate adaptation requires a better understanding of global and regional processes influencing RWHTs adoption combined with pre-existing analysis at the household scale. On the basis of a systematic literature review, processes of influence in the diffusion and uptake of RWHTs are identified. These relate to shifting ideology associated with food production systems; the scope of investments in agriculture science and technology; emergent actors shaping development assistance; and patterns of farmer mobility. Drawing insights from theory on transformations for sustainability and development, this article adds to the understanding of connectedness between farm-level adoption of RWHTs, and regional to global level actors, institutions and processes.
      Graphical abstract image

      PubDate: 2015-03-10T08:35:25Z
  • Preconcentration and spectrophotometric determination of polyDADMAC in
           treated water by in situ co-precipitation with naphthalene
    • Abstract: Publication date: 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volumes 72–75
      Author(s): Isaac W. Mwangi , J. Catherine Ngila , Patrick Ndungu , T. Msagati
      Polydiallyldimethylammonium chloride (polyDADMAC) is a water-soluble cationic polyelectrolyte used as a flocculant in water treatment works. Unreacted traces in water react with chlorine to produce a carcinogenic compound during the disinfectation process. This study reports on a preconcentration procedure and spectrophotometric determination of polyDADMAC at trace levels in treated water by in situ co-precipitation with naphthalene with a view to come up with an analytical tool that will be used by water works to routinely monitor the polycation in an effort to supply safe water to consumers. Preconcentration of polyDADMAC polyelectrolyte in water at trace levels was achieved by co-precipitating the polyelectrolyte with naphthalene. This resulted in the formation of a water insoluble adsorbent with a high affinity for azo dyes. The formation of this material was based on multilayer assembly of organic polyelectrolyte systems resulting to multilayers through a layer-by-layer self-assembly process. The co-precipitate was formed by mixing aqueous solutions containing varying concentrations of polyDADMAC with different volumes of solutions containing 0.75g of naphthalene dissolved in acetone. The resulting respective precipitates were packed in different glass columns and a solution of the dye was eluted through each column. The contents of each column were then dissolved in 10mL of dimethylformamide (DMF) and the absorbance readings of the resulting solutions recorded. The wavelength of maximum absorption was found to be 540nm at pH 12.0. A linear calibration for polyDADMAC solutions was obtained with a correlation coefficient of 0.976. The detection limit was found to be 1.90×10−4 μgmL−1 and the method was applied to determine the concentration of polyDADMAC residue in treated water.

      PubDate: 2015-03-10T08:35:25Z
  • The Viability Assessment of Microcystis aeruginosa cells after
           co-culturing with Bacillus mycoides B16 Using Flow Cytometry
    • Abstract: Publication date: Available online 2 October 2014
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): JR Gumbo , TE Cloete , GJJ van Zyl , JEM Sommerville
      Microcystis aeruginosa is the dominate cyanobacteria in freshwater bodies causing proliferation of toxic harmful algal blooms (HABs), worldwide. Thus a biological control method based on predatory bacteria is an alternative environmental solution to the control of these HABs, A Flow cytometric technique was used to assess the viability of Microcystis spp cells after deliberate co-culturing with a predatory bacterium, Bacillus mycoides B16. Under static conditions, B. mycoides had a lytic effect on Microcystis cells that resulted in a significant (p = 0.0000) population decline of 97% in six days. In contrast under turbulent conditions, B. mycoides had a lytic effect on Microcystis spp cells resulting in a significant (df = 5; t = -7.21; p= 0.0003) population decrease of 85% in the same time period. The Levene test also showed a significant (p = 0.0003) decrease in Microcystis cell numbers, which also coincided with a significant (t = 11.31; p = 0.0001) increase in B. mycoides cell numbers. This suggested that B. mycoides, a heterotroph, was utilizing the Microcystis as a source of nutrition. The effect of agitation may have contributed to the delay in cell lysis as it disturbed the physical contact between the predator and prey. The control samples showed a significant (df = 5; t = + 6.86; p = 0.0010) increase in Microcystis spp cell numbers. B. mycoides was able to lyse Microcystis spp cells under these conditions and may thus be considered as a potential biological control agent for the management of Microcystis spp harmful algal blooms.

      PubDate: 2014-10-02T23:57:57Z
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