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Journal Cover Physics and Chemistry of the Earth, Parts A/B/C
  [SJR: 0.611]   [H-I: 26]   [6 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1474-7065
   Published by Elsevier Homepage  [3039 journals]
  • Simulation of the effect of an oil refining project on the water
           environment using the MIKE 21 model
    • Authors: Peng Jia; Qinggai Wang; Xuchuan Lu; Beibei Zhang; Chen Li; Sa Li; Shibei Li; Yaping Wang
      Abstract: Publication date: Available online 13 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Peng Jia, Qinggai Wang, Xuchuan Lu, Beibei Zhang, Chen Li, Sa Li, Shibei Li, Yaping Wang
      A case study of the Caofeidian oil refining project is conducted. A two-dimensional convective dispersion mathematical model is established to simulate the increase in the concentration of pollutants resulting from the wastewater discharge from the Caofeidian oil refining project and to analyze the characteristics of the dispersion of pollutants after wastewater is discharged and the effect of the wastewater discharge on the surrounding sea areas. The results demonstrate the following: (1) The Caofeidian sea area has strong tidal currents, which are significantly affected by the terrain. There are significant differences in the tidal current velocity and the direction between the deep-water areas and the shoals. The direction of the tidal currents in the deep-water areas is essentially parallel to the contour lines of the sea areas. Onshore currents and rip currents submerging the shoals are the dominant currents in the shoals. (2) The pollutant concentration field in the offshore areas changes periodically with the movement of the tidal current. The dilution and dispersion of pollutants are affected by the ocean currents in different tidal periods. The turbulent dispersion of pollutants is the most intense when a neap tide ebbs, followed by when a neap tide rises, when a spring tide ebbs and when a spring tide rises. (3) There are relatively good hydrodynamic conditions near the project's wastewater discharge outlet. Wastewater is well diluted after being discharged. Areas with high concentrations of pollutants are concentrated near the wastewater discharge outlet and the offshore areas. These pollutants migrate southwestward with the flood tidal current and northeastward with the ebb tidal current and have no significant impact on the protection targets in the open sea areas and nearby sea areas.

      PubDate: 2017-02-15T20:46:42Z
      DOI: 10.1016/j.pce.2017.02.003
       
  • Distribution and source identification of trace metals in the sediment of
           Yellow River Estuary and the adjacent Laizhou Bay
    • Authors: Yan Wang; Min Ling; Ru-hai Liu; Ping Yu; Ai-kun Tang; Xian-xiang Luo; Qimin Ma
      Abstract: Publication date: Available online 11 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Yan Wang, Min Ling, Ru-hai Liu, Ping Yu, Ai-kun Tang, Xian-xiang Luo, Qimin Ma
      Rapid economic development in the Yellow River basin has inevitably resulted in increase of pollutions in the estuary, and concern for both the environment and protection against pollutants is increasing. Contents of trace metals (Cu, Pb Zn, Cr, Cd, As, Hg), Fe, Al, total organic carbon (TOC), and their granulometry were determined in surface sediment samples from the Yellow River estuary and its adjacent areas. Metal contents were significantly correlated each other. Clay, TOC and heavy metal contents showed similar distribution characteristics, with concentrations increased from the land to the sea. The distribution of grain size plays an important role in influencing the distribution of trace metals. Heavy metal concentrations showed a significant relationship with Fe and Al content, while most heavy metals were not enriched. These results were also confirmed by the analysis of enrichment factors and principal component analysis of the metals. The metal content of the Yellow River Estuary sediments was similar to the content observed 20 years ago, but the concentrations of most metals in Laizhou Bay decreased. The decrease in the carrying sediment of the Yellow River might be responsible for this pattern.

      PubDate: 2017-02-15T20:46:42Z
      DOI: 10.1016/j.pce.2017.02.002
       
  • Reactive transport models of a high–pH infiltration test in concrete
    • Authors: M. Carme Chaparro; Josep M. Soler; Maarten W. Saaltink; Urs K. Mäder
      Abstract: Publication date: Available online 4 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M. Carme Chaparro, Josep M. Soler, Maarten W. Saaltink, Urs K. Mäder
      A laboratory-scale tracer test was carried out to characterize the transport properties of concrete from the Radioactive Waste Disposal Facility at El Cabril (Spain). A hyperalkaline solution (K-Ca-OH, pH = 13.2) was injected into a concrete sample under a high entry pressure in order to perform the experiment within a reasonable time span, obtaining a decrease of permeability by a factor of 1000. The concentrations of the tracers, major elements (Ca2+, SO4 2−, K+ and Na+) and pH were measured at the outlet of the concrete sample. A reactive transport model was built based on a double porosity conceptual model, which considers diffusion between a mobile zone, where water can flow, and an immobile zone without any advective transport. The numerical model assumed that all reactions took place in the immobile zone. The cement paste consists of C-S-H gel, portlandite, ettringite, calcite and gypsum, together with residual alite and belite. Two different models were compared, one with portlandite in equilibrium (high initial surface area) and another one with portlandite reaction controlled by kinetics (low initial surface area). Overall the results show dissolution of alite, belite, gypsum and quartz and precipitation of C-S-H gel, portlandite, ettringite and calcite. Permeability could have decreased due to mineral precipitation.

      PubDate: 2017-02-09T20:42:20Z
      DOI: 10.1016/j.pce.2017.01.010
       
  • Use of Landsat series data to analyse the spatial and temporal variations
           of land degradation in a dispersive soil environment: A case of King
           Sabata Dalindyebo local municipality in the Eastern Cape Province, South
           Africa
    • Authors: Timothy Dube; Onisimo Mutanga; Mbulisi Sibanda; Khoboso Seutloali; Cletah Shoko
      Abstract: Publication date: Available online 4 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Timothy Dube, Onisimo Mutanga, Mbulisi Sibanda, Khoboso Seutloali, Cletah Shoko
      Land degradation as a result of inappropriate land use practices, such as overgrazing and cultivation on steep slopes, etc. is one of the major global environmental challenges. Specifically, land degradation threatens the productivity and sustainability of the natural environment, agriculture, and most importantly rural economies in most developing countries, particularly the sub-Saharan region. The main aim of this study was therefore, to assess the potential and strength of using the free or readily available Landsat series data in mapping degraded land areas at the King Sabata Dalindyebo local municipality in the Eastern Cape, South Africa (1984–2010). Data analysis was done using a robust non-parametric classification ensemble; Discriminant Analysis (DA). The results show that degraded areas vary over the years. For example, the results show that the year 1994 and 2004 incurred high degradation levels, when compared to the year 1984 and 2010. Moreover, the observed degradation significantly (α = 0.05) varies with soil type. The chromic acrisols have the highest levels of erosion (approx. 80% in 1984), when compared to humic-umbric acrisols (less than 10% for the entire period under study). It can also be observed that considerable part of degradation occurred in the northern part of the municipal district. Overall, the findings of this research underlines the importance and efficacy of multispectral Landsat series data-set in mapping and monitoring levels of land degradation in data-scarce catchments.

      PubDate: 2017-02-09T20:42:20Z
      DOI: 10.1016/j.pce.2017.01.023
       
  • Potential application of synthesized ferrocenylimines compounds for the
           elimination of bacteria in water
    • Authors: M.I. Ikhile; T.G. Barnard; J.C. Ngila
      Abstract: Publication date: Available online 4 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): M.I. Ikhile, T.G. Barnard, J.C. Ngila
      This work reports a study towards a search for environmentally friendly water disinfectant. The most common method for water treatment is based on chlorine which had a wide application over the years as a water disinfectant, but suffer the disadvantage of reacting with natural organic matter to form disinfection by products. In this study, the potential application of novel ferrocenylimines compounds, namely 4-ferrocenylaniline (1), N-(3-bromo-2-hydroxylbenzylidene)-4-ferrocenylimine (2) and N-(3-bromo-5-chlorosalicyl)-4-ferrocenylimine (3) for the elimination of bacteria in water was investigated by evaluating their antibacterial properties against twelve different bacterial strains using microdilution method in sterile 96 well micro titer plates. The in vitro antibacterial activity revealed that the ferrocenylimines compound exhibit higher antibacterial activity than ferrocene, which is one of the starting materials towards the synthesis of this novel ferrocenylimines compounds. The most active ferrocenylimines compound was compound 3 with a minimal inhibitory concentration (MIC) value of 0.30 mg/ml against S. sonnei. In addition, all the ferrocenylimines compounds possessed excellent antibacterial activity against B. cereus with the same MIC value of 0.31 mg/ml. The results obtained so far show great potential in the three tested ferrocenylimines compounds for use in water treatment in killing bacteria in water.

      PubDate: 2017-02-09T20:42:20Z
      DOI: 10.1016/j.pce.2017.01.022
       
  • Denitrification of soil nitrogen in coastal and inland salt marshes with
           different flooding frequencies
    • Authors: Junhong Bai; Xin Wang; Jia Jia; Guangliang Zhang; Wei Wang; Shuai Zhang
      Abstract: Publication date: Available online 3 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Junhong Bai, Xin Wang, Jia Jia, Guangliang Zhang, Wei Wang, Shuai Zhang
      Denitrification is an important process for removing nitrogen in wetlands, and it is influenced by many environmental factors. However, little information is available on the relationship between hydrologic conditions and denitrification. In this study three typical sampling sites with different flooding frequencies, including short-term flooding wetlands (STFW), seasonal-flooding wetlands (SFW) and tidal flooding wetlands (TFW) were chosen as the study sites in the Yellow River Delta. In contrast, five typical sampling sites with different flooding frequencies, including 100-year floodplain (H), 10-year floodplain (T), 5-year floodplain (F), 1-year floodplain (O) and permanently flooded floodplain (B) were chosen as the study sites in Xianghai wetlands. This study reflected that the denitrification rates decreased with depth along soil profiles in both inland and coastal salt marsh soils. Flooding periods, soil depth and their interaction showed significant effects on the denitrification processes. Generally, higher flooding frequencies will cause higher denitrification rates in salt marshes. Moreover, the denitrification rates were significantly positively correlated with soil moisture content in both wetlands. Additionally, the denitrification rates were significantly positively correlated with organic matter and NO3 -_N content while negatively correlated with soil pH and salinity in inland salt marshes. Therefore, the changes in soil properties (e.g. SOM, TN, pH and salinity) can become an important way to control NO3 - levels in inland salt marshes.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.015
       
  • Effect of incorporating graphene oxide and surface imprinting on
           polysulfone membranes on flux, hydrophilicity and rejection of salt and
           polycyclic aromatic hydrocarbons from water
    • Authors: Rose Waithiegeni Kibechu; Derek Dinteh; Titus Alfred Makudali Msagati; Bhekie Briliance Mamba
      Abstract: Publication date: Available online 3 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Rose Waithiegeni Kibechu, Derek Dinteh, Titus Alfred Makudali Msagati, Bhekie Briliance Mamba
      We report a significant enhancement of hydrophillity of polysulfone (Psf) membranes after modification with graphene oxide (GO) as a filler followed by surface imprinting on the surface of GO/Psf composite imprinted membranes (CIMs). The surface imprinting on the GO-Psf membrane was employed in order to enhance its selectivity towards polycyclic aromatic hydrocarbons (PAHs) in water. The CIMs were prepared through a process of phase inversion of a mixture of graphene oxide and polysulfone (Psf) in N-methylpyrrolidone (NMP). Fourier-transform spectroscopy (FT-IR) of the imprinted showed new peaks at 935 cm−1 and 1638 cm−1 indicating success in surface imprinting on the GO-Psf membrane. The CIM also showed improvement in flux from 8.56 LM−2 h−1 of unmodified polysulfone membrane to 15.3 LM−2 h−1 in the CIM, salt rejection increased from 57.2 ± 4.2% of polysulfone membrane to 76 ± 4.5%. The results obtained from the contact angle measurements showed a decrease with increase in GO content from 72 ± 2.7% of neat polysulfone membrane to 62.3 ± 2.1% of CIM indicating an improvement in surface hydrophilicity. The results from this study shows that, it is possible to improve the hydrophilicity of the membranes without affecting the performance of the membranes.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.021
       
  • Scenario simulation of land exploitation and risk assessment of soil
           erosion in the low-slope hilly area of the Erhai basin
    • Authors: Gui Jin; Xiangzheng Deng; Yongwei Yuan; Sai Ma; Zhaohua Li; Saiya Shi
      Abstract: Publication date: Available online 3 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Gui Jin, Xiangzheng Deng, Yongwei Yuan, Sai Ma, Zhaohua Li, Saiya Shi
      Risk assessment of soil erosion is an important prerequisite to develop the low-slope hilly in basin-scale. Using Dynamics of Land System model (DLS), we design the scenario simulation of land exploitation of Dali city which is located in the Erhai basin and typical as low-slope hilly area. Then we bring in Universal Soil Loss Equation (USLE) to assess the risks of soil erosion under different scenarios. In two simulating scenarios, baseline scenario and planning scenario respectively, the spatial distribution pattern of land use of the study area in 2020 shows an overall consistency and a partial difference. The cultivated resources of Dali has been protected since the cultivated land located in dam area has not changed, while construction land has expanded more or less on the basis of existing built-up areas. Specifically, the expansion of construction land in planning scenario is concentrated on Haidong town and Fengyi town where there are rich in low-slope hilly resources. In two scenarios mentioned above, both the value-at-risk of soil erosion and its risk level have no significant rise or drop from 2008 to 2020. As the risk index of soil erosion in baseline scenario is 0.003 taller than in planning scenario, one conclusion can be drawn that the planning scenario will lower the overall risk of soil erosion and should be used to develop gentle hillside area in Erhai basin. The risk evaluation of soil erosion under different scenarios is valuable for land management decisions because the results provide fundamental information for optimal utilization of land use and prevention of ecological risks in the low-slope hilly regions.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.020
       
  • Estimating groundwater levels using system identification models in
           Nzhelele and Luvuvhu areas, Limpopo Province, South Africa
    • Authors: Rachel Makungo; John O. Odiyo
      Abstract: Publication date: Available online 3 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Rachel Makungo, John O. Odiyo
      This study was focused on testing the ability of a coupled linear and non-linear system identification model in estimating groundwater levels. System identification provides an alternative approach for estimating groundwater levels in areas that lack data required by physically-based models. It also overcomes the limitations of physically-based models due to approximations, assumptions and simplifications. Daily groundwater levels for 4 boreholes, rainfall and evaporation data covering the period 2005–2014 were used in the study. Seventy and thirty percent of the data were used to calibrate and validate the model, respectively. Correlation coefficient (R), coefficient of determination (R2), root mean square error (RMSE), percent bias (PBIAS), Nash Sutcliffe coefficient of efficiency (NSE) and graphical fits were used to evaluate the model performance. Values for R, R2, RMSE, PBIAS and NSE ranged from 0.8 to 0.99, 0.63 to 0.99, 0.01–2.06 m, −7.18 to 1.16 and 0.68 to 0.99, respectively. Comparisons of observed and simulated groundwater levels for calibration and validation runs showed close agreements. The model performance mostly varied from satisfactory, good, very good and excellent. Thus, the model is able to estimate groundwater levels. The calibrated models can reasonably capture description between input and output variables and can, thus be used to estimate long term groundwater levels.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.019
       
  • Effect of coastal eutrophication on growth and physiology of Spartina
           alterniflora Loisel
    • Authors: Yu Zhang; Baoshan Cui; Tian Xie; Qing Wang; Jiaguo Yan
      Abstract: Publication date: Available online 3 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Yu Zhang, Baoshan Cui, Tian Xie, Qing Wang, Jiaguo Yan
      Coastal eutrophication has become a driver of coastal wetlands loss. Eutrophication caused by the increase of nitrogen content was one of the most main reasons. We analyzed that exogenous ammonium nitrogen (EAN) of different concentration influenced on the growth and physiology of Spartina alterniflora Loisel (S. alterniflora) through simulated conditions. The results showed that growth of the root system largely depended on the environment conditions around S. alterniflora. Higher nitrogen concentration promoted aboveground biomass and increased plant height. On the other hand, as the increase of growth period, higher nitrogen concentration could inhibit the elongation growth of root and reduce the underground biomass. We showed that activity of POD, SOD and MDA content changed in an upward trend along with the increased nitrogen level. There was a significant positive correlation between H+ flux and NO3 - flux (r = 0.601, P < 0.01), and a significant negative correlation between H+ flux and NH4 + flux (r = –0.713, P < 0.01) within 1.5 mm from the root tip of S. alterniflora. Efflux and influx of ions were associated with changes of nitrogen levels. This research will provide data supporting for coastal wetland restoration of biodiversity reduction caused by coastal eutrophication.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.016
       
  • Land-use-change induced dynamics of carbon stocks of the terrestrial
           ecosystem in Pakistan
    • Authors: Dongdong Chen; Xiangzheng Deng; Gui Jin; Abdus Samie; Zhaohua Li
      Abstract: Publication date: Available online 3 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Dongdong Chen, Xiangzheng Deng, Gui Jin, Abdus Samie, Zhaohua Li
      In recent years, dramatic decline of ecosystem service due to large scale human induced land use change activities, which has received much attention of researchers as diminishing of ecosystem function affects the sustainability of human society, economy and environmental protection. The study aims to analyze the impact of land use change on ecosystem service of carbon sequestration in Pakistan. This study, based on Dynamics of Land System (DLS) model, simulating the future land use changes, combing with Integrated Valuation of Environmental Services and Trade-offs (InVEST) model, has analyzed the changes in quantity and distribution of carbon stock in Pakistan under alternative land use scenarios for 2020 using historical land use data from 2006 to 2009. The results indicate that comparing the carbon stocks in 2009, only the Business-as-usual scenario of carbon stocks continue to decrease; the other two scenarios of carbon stocks show the increasing trend. Moreover, the Ecological protection scenario has the highest carbon storage, but it is not feasible to the current conditions of Pakistan, whereas Investment priority oriented scenario could be ideal one. The advances in research underpin scientific efforts to connect dynamic land use change with ecosystem service of carbon storage in Pakistan.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.018
       
  • Traditional Portland cement and MgO-based cement: a promising
           combination?
    • Authors: Monica Tonelli; Francesca Martini; Lucia Calucci; Marco Geppi; Silvia Borsacchi; Francesca Ridi
      Abstract: Publication date: Available online 2 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Monica Tonelli, Francesca Martini, Lucia Calucci, Marco Geppi, Silvia Borsacchi, Francesca Ridi
      MgO/SiO2 cements are materials potentially very useful for radioactive waste disposal, but knowledge about their physico-chemical properties is still lacking. In this paper we investigated the hydration kinetics of cementitious formulations prepared by mixing MgO/SiO2 and Portland cement in different proportions and the structural properties of the hydrated phases formed in the first month of hydration. In particular, the hydration kinetics was investigated by measuring the free water index on pastes by means of differential scanning calorimetry, while the structural characterization was carried out by combining thermal (DTA), diffractometric (XRD), and spectroscopic (FT-IR, 29Si solid state NMR) techniques. It was found that calcium silicate hydrate (C-S-H) and magnesium silicate hydrate (M-S-H) gels mainly form as separate phases, their relative amount and structural characteristics depending on the composition of the hydrated mixture. Moreover, the composition of the mixtures strongly affects the kinetics of hydration and the pH of the aqueous phase in contact with the cementitious materials. The results here reported show that suitable mixtures of Portland cement and MgO/SiO2 could be used to modify the properties of hydrated phases with potential application in the storage of nuclear waste in clayey disposal.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.011
       
  • Effect of particulate air pollution on coronary heart disease in China:
           Evidence from threshold GAM and Bayesian hierarchical model
    • Authors: Xiaoyu Chen
      Abstract: Publication date: Available online 2 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xiaoyu Chen
      There are few multicity studies to address the effect of short-term effect of particulate matter air pollution on daily Coronary Heart Disease (CHD) mortality in developing countries, much fewer to further discuss its threshold and seasonal effect. This study investigates the season-varying association between particulate matter less than or equal to 10 μm in aerodynamic diameter (PM10) and daily CHD mortality in seven cities of China. Time series threshold Poisson regression model is specified to estimate the health effect for four cities with the threshold effect, and conventional linear Poisson model is used to analyze the effect for three cities without threshold. We apply the Bayesian hierarchical model to pool the city-specific estimates into overall level. On average, a 10 μg/m3 increase of the moving average concentrations of current-day and previous-day PM10 is associated with an increase of 0.81% (95% Posterior Interval, PI: −0.04%, 1.67%) in daily CHD mortality for all the cities as a whole. The associations are smaller than reported in developed countries or regions with lower polluted level, which is consistent to the findings in the literature. The hazardous effect are higher in hot summer and cold winter (1.15% and 0.89%) but lower in relative warm spring and fall (0.85% and 0.69%). In summary, we found significant associations between short-term exposure to PM10 and CHD mortality in China. The sensitivity analyses in the study support the robustness of our results.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.013
       
  • Understanding land use change impacts on microclimate using Weather
           Research and Forecasting (WRF) Model
    • Authors: Xia Li; Chandana Mitra; Li Dong; Qichun Yang
      Abstract: Publication date: Available online 2 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xia Li, Chandana Mitra, Li Dong, Qichun Yang
      To explore potential climatic consequences of land cover change in the Kolkata Metropolitan Development area, we projected microclimate conditions in this area using the Weather Research and Forecasting (WRF) Model driven by future land use scenarios. Specifically, we considered two land conversion scenarios including an urbanization scenario that all the wetlands and croplands would be converted to built-up areas, and an irrigation expansion scenario in which all wetlands and dry croplands would be replaced by irrigated croplands. Results indicated that land use and land cover (LULC) change would dramatically increase regional temperature in this area under the urbanization scenario, but expanded irrigation tended to have a cooling effect. In the urbanization scenario, precipitation center tended to move eastward and lead to increased rainfall in eastern parts of this region. Increased irrigation stimulated rainfall in central and eastern areas but reduced rainfall in southwestern and northwestern parts of the study area. This study also demonstrated that urbanization significantly reduced latent heat fluxes and albedo of land surface; while increased sensible heat flux changes following urbanization suggested that developed land surfaces mainly acted as heat sources. In this study, climate change projection not only predicts future spatiotemporal patterns of multiple climate factors, but also provides valuable insights into policy making related to land use management, water resource management, and agriculture management to adapt and mitigate future climate changes in this populous region.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.017
       
  • Salinity-driven shifts in the activity, diversity, and abundance of
           anammox bacteria of estuarine and coastal wetlands
    • Authors: Xiaofen Jiang; Lijun Hou; Yanling Zheng; Min Liu; Guoyu Yin; Juan Gao; Xiaofei Li; Rong Wang; Chendi Yu; Xianbiao Lin
      Abstract: Publication date: Available online 2 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xiaofen Jiang, Lijun Hou, Yanling Zheng, Min Liu, Guoyu Yin, Juan Gao, Xiaofei Li, Rong Wang, Chendi Yu, Xianbiao Lin
      Anaerobic ammonium oxidation (anammox) plays a significant role in nitrogen removal in estuarine and coastal wetlands. However, the effects of changing salinity on anammox activity and anammox bacterial dynamics in these environments are not well understood. In this study, serial incubation experiments with a salinity gradient (0-40) were conducted to explore the responses of anammox bacterial activity, diversity and abundance to the changing salinity in the intertidal wetland of the Yangtze Estuary. Results show that activity and abundance of anammox bacteria firstly increased with the increase of salinity, but they were physiologically stressed by high-level salinity (>30) in a short-term incubation (<10 days). However, the treatment with salinity of 5 showed the maximal anammox activity and anammox bacterial abundance after a long-term incubation (60-120 days). In addition, Kuenenia (Kuenenia stuttgartiensis), Scalindua (Scalindua wagner, marina, and brodae), and three unknown anammox-like groups were observed, and anammox bacterial diversity increased along the salinity gradient. Anammox community structure varied slightly within the first 10-day incubation, but the dominant anammox bacterial group shifted from Kuenenia to Scalindua with increasing salinity after the long-term incubation. Overall, this study demonstrates the effects of salinity on anammox bacterial community and anammox activity, and suggests the importance of salinity in regulating the anammox process in estuarine and coastal wetlands with frequent salinity fluctuation.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.012
       
  • Impact assessments of water allocation on water environment of river
           network: Method and application
    • Authors: Qinggai Wang; Yaping Wang; Xuchuan Lu; Peng Jia; Beibei Zhang; Chen Li; Sa Li; Shibei Li
      Abstract: Publication date: Available online 2 February 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Qinggai Wang, Yaping Wang, Xuchuan Lu, Peng Jia, Beibei Zhang, Chen Li, Sa Li, Shibei Li
      Two types of water allocation senarioes were proposed for reasonably utilizing water resources and improving water quality in a two-river network in Tongzhou District. Water circulation and quality were selected as two important indexes to evaluate the two senarioe. Meanwhile, one-dimensional water amount and quality model was set up on the basis of the MIKE11 model to compare the two senarioes in terms of improving water environment. The results showed that both senarioes changed the hydrodynamic conditions, and consequently the river flow reached 0.05 m/s or higher in the central part of river stream. In addition, we also found that the two plans have similar effects on water quality, with first senarioe producing larger area of water class III and IV than the second senarioe.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.014
       
  • Articulating the history and major departure points evident in
           post-apartheid South African national water policy and law
    • Authors: C. Chikozho; L. Danga; D. Saruchera
      Abstract: Publication date: Available online 28 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): C. Chikozho, L. Danga, D. Saruchera
      Governance of the water sector in South Africa has reflected the political changes taking place in society. For instance, due to apartheid policies of segregation, inequality of access to water resources marks South Africa's history in a very profound way and redistribution of rights to water to redress the results of past discrimination became an explicit purpose of the post-apartheid water governance policy and legislative regime. In this paper, we articulate the history and major departure points evident in post-apartheid South African national water policy and law. This includes documenting and reflecting on most of the available information that shows how the new water policy and law were developed. Findings from the study show that the key players active in the water law review process deliberately took into account the political goals and dynamics of power asymmetry within which the law was being articulated. Therefore, the water law as it stands today and in the past must be understood within the context of the socio-economic and political landscape that has prevailed in South Africa at different historical junctures. We contend that a detailed examination and articulation of the history and major departure points evident in post-apartheid South African national water policy and law enables practitioners and scholars to better understand the main motivations behind the water sector reforms and the then prevailing thinking behind the policy and legislation eventually promulgated. The present water law must be understood in the context of these reforms and the objectives they sought to achieve.

      PubDate: 2017-02-03T20:37:49Z
      DOI: 10.1016/j.pce.2017.01.006
       
  • Site - building resonance response in a complex geological setting: Ground
           motions recorded in the centre of Paleohora Basin and at a rock fractured
           outcrop site close to the basin edge (SW Crete, Greece)
    • Authors: Margarita Moisidi
      Abstract: Publication date: Available online 27 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Margarita Moisidi
      Seismic site characterization is an important parameter in earthquake hazard assessment for risk mitigation studies, which are essential in engineering design practices and urban planning providing useful information to governmental or private civil protection authorities. Recent advances from site effect studies envisage for the future the importance of incorporating microzonation as a tool for determining resonance prone buildings especially for the most earthquake hazardous municipalities. This study aims to assess the frequencies of vibration of selected masonry and reinforced concrete buildings and to examine potential soil - building resonance in a complex geological setting of the small scale Paleohora Basin (southwest Crete). Ambient noise survey was performed in masonry and reinforced concrete buildings, on soil foundation and on soil at several distances from the base of the selected buildings. The selected public and private (masonry and RC) building constructions are located in the centre of the Basin which is characterized by heterogeneities induced by large scale E-W fault and at rock fractured (of complex orientation and opening of fractures and joints) outcrop site close to the margins of the Basin in the southeast bordered by an NNE-SSW fault. The spatial horizontal to vertical spectral ratio (HVSR) technique using ambient noise reveals that soil-building resonance phenomena could be inferred in the small scale alluvial Paleohora Basin. Two amplified peaks in the centre of the Basin and one amplified peak at the rock fractured outcrop site close to the Basin margins are observed from the data sets. In the centre of the Basin, the amplified peak at medium frequency (3.85–7.11 Hz) is related to the near subsurface irregularities locally induced by E-W faulting, while the low frequency (0.75 Hz) is related to the overlain Quaternary deposits. At the rock fractured outcrop site close to the margins of the Basin the one amplified peak at medium frequencies (2.5 Hz) is related to the fractured limestone outcrop. Weak motion earthquake data following the main earthquake event that occurred near to the southwest coast of Paleohora are recorded in the centre of the Basin (at the schoolyard) and on rock fractured outcrop close to the margins of the Basin. The HVSR of the weak motion earthquake data present in the center of the Basin two amplified peaks at low (0.75 Hz) and medium frequencies (6.56 Hz) and at the rock fractured outcrop site close to the Basin edge one amplified peak at medium frequencies (2.58 Hz). This study conducted in the complex small scale and dense populated Basin, highlights the necessity of incorporating the determination of prone resonance buildings into urban planning for risk mitigation studies, specifically in this earthquake hazardous municipality.

      PubDate: 2017-01-27T19:58:10Z
      DOI: 10.1016/j.pce.2017.01.007
       
  • Detecting CO2 anomalies in a spring on Mt. Amiata volcano (Italy)
    • Authors: L. Pierotti; F. Gherardi; G. Facca; L. Piccardi; G. Moratti
      Abstract: Publication date: Available online 27 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): L. Pierotti, F. Gherardi, G. Facca, L. Piccardi, G. Moratti
      Located at the south-western slope of the Mt. Amiata volcano (Tuscany, Central Italy), the Bagnore spring has been investigated for geochemical precursors of earthquakes from 2004 to 2015. Over this period, several parameters of the spring have been monitored by discrete and continuous sampling. An automatic continuous monitoring station, equipped with sensors for the measurement of temperature, pH, redox potential, electrical conductivity, CO2 and CH4 dissolved concentration, is transmitting the registered signals to the remote server in Pisa 150 km northwest of Mt. Amiata. The Bagnore spring drains a shallow, short-circuiting aquifer hosted in the volcanic rocks of the volcano. Its emergence point is located in proximity of the intersection of two major fault systems that are supposed to provide a preferential ascent path to hydrothermal gases, mainly represented by C O 2 ( g ) and H 2 S ( g ) , locally rising from depth. The most evident change occurred in the registered signals over the period is represented by the sudden increase in CO2 concentration measured starting from April 2010. Along with this increase in CO2, a slight increase in water temperature and in S O 4 concentration, associated to a decrease in pH, was also recorded. This trend has been interpreted as an evidence for the augmented inflow of deep gases into the shallow aquifer. The CO2 continuous signal recorded by the Bagnore automatic station has been then processed by applying multiple statistical techniques (i.e. artificial neural network analysis and Census I method) in the search for anomalies possibly related to local seismic activity. Anomalous signals have been detected starting from April 24, 2010, and the correlation with the most energetic seismic events has been tentatively proposed.

      PubDate: 2017-01-27T19:58:10Z
      DOI: 10.1016/j.pce.2017.01.008
       
  • In situ interactions between Opalinus Clay and Low Alkali Concrete
    • Authors: Catherine Lerouge; Stéphane Gaboreau; Sylvain Grangeon; Francis Claret; Fabienne Warmont; Andreas Jenni; Veerle Cloet; Urs Mäder
      Abstract: Publication date: Available online 18 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Catherine Lerouge, Stéphane Gaboreau, Sylvain Grangeon, Francis Claret, Fabienne Warmont, Andreas Jenni, Veerle Cloet, Urs Mäder
      A five-year-old interface between a Low Alkali Concrete (LAC) formulation (CEM III/B containing 66% slag and 10% nano-silica) and Opalinus Clay (OPA) from a field experiment at Mont Terri Underground Rock Laboratory in Switzerland (Jenni et al., 2014) has been studied to decipher the textural, mineralogical and chemical changes that occurred between the two reacting materials. Reactivity between LAC concrete and OPA is found to be limited to a ∼1mm thick highly porous (ca. 75% porosity) white crust developed on the concrete side. Quantitative mineralogical mapping of the white crust using an electron microprobe and infrared spectroscopy on the cement matrix provides evidence of a Mg-rich phase accounting for approximatively 25 weight % of the matrix associated with 11 weight % of calcite, calcium silicate hydrate (C-S-H) and other cement phases. EDX analyses and electron diffraction combined with transmission electron microscopy of the Mg-rich phase provide evidence for a tri-octahedral 2:1 phyllosilicate with mean composition: (Ca0.5±0.2) (Mg2.0±0.4, Fe0.2±0.1, Al0.5±03, □0.3±0.3) (Al0.9±0.2, Si3.1±0.2) O10 (OH)2, where □ represents vacancies in the octahedral site Apart from this reactive contact, textural, mineralogical and chemical modifications at the contact with the LAC concrete are limited. OPA mineralogy remains largely unmodified. X-ray micro-fluorescence and EPMA mapping of major elements on the OPA side also provides evidence for a Mg-enriched 300 to 400μm thick layer. The cation exchange capacity (CEC) values measured in the OPA in contact with the LAC concrete range between 153 and 175 meq kg−1 of dry OPA, close to the reference value of 170 ± 10 meq kg−1 of dry OPA (Pearson et al., 2003). Changing cation occupancies at the interface with LAC concrete are mainly marked by increased Ca, Mg and K, and decreased Na. Leaching tests performed on OPA with deionized water and at different solid to water ratios strongly suggest that Cl and SO4 have either conservative behaviour or are constrained by the solubility of a precipitated sulfate phase. The Cl and SO4 concentrations measured at 2 cm from the interface are close to concentrations of undisturbed OPA pore waters (SO4: 4.5 ± 1.5 mmol kg−1 of dry OPA; Cl: 7.5 ± 2.1 mmol kg−1of dry OPA), and increase towards the interface with the concrete. The SO4 to Cl ratio also increases towards the interface, suggesting that the increasing anion concentrations are not related to porosity variations but rather to a concentration gradient and sulfate phase precipitation near the interface.

      PubDate: 2017-01-21T19:21:49Z
      DOI: 10.1016/j.pce.2017.01.005
       
  • Interaction of ordinary Portland cement and Opalinus Clay: dual porosity
           modelling compared to experimental data
    • Authors: A. Jenni; T. Gimmi; P. Alt-Epping; U. Mäder; V. Cloet
      Abstract: Publication date: Available online 18 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): A. Jenni, T. Gimmi, P. Alt-Epping, U. Mäder, V. Cloet
      Interactions between concrete and clays are driven by the strong chemical gradients in pore water and involve mineral reactions in both materials. In the context of a radioactive waste repository, these reactions may influence safety-relevant clay properties such as swelling pressure, permeability or radionuclide retention. Interfaces between ordinary Portland cement and Opalinus Clay show weaker, but more extensive chemical disturbance compared to a contact between low-pH cement and Opalinus Clay. As a consequence of chemical reactions porosity changes occur at cement-clay interfaces. These changes are stronger and may lead to complete pore clogging in the case of low-pH cements. The prediction of pore clogging by reactive transport simulations is very sensitive to the magnitude of diffusive solute fluxes, cement clinker chemistry, and phase reaction kinetics. For instance, the consideration of anion-depleted porosity in clays substantially influences overall diffusion and pore clogging at interfaces. A new concept of dual porosity modelling approximating Donnan equilibrium is developed and applied to an ordinary Portland cement – Opalinus Clay interface. The model predictions are compared with data from the cement-clay interaction (CI) field experiment in the Mt Terri underground rock laboratory (Switzerland), which represent 5 y of interaction. The main observations such as the decalcification of the cement at the interface, the Mg enrichment in the clay detached from the interface, and the S enrichment in the cement detached from the interface, are qualitatively predicted by the new model approach. The model results reveal multiple coupled processes that create the observed features. The quantitative agreement of modelled and measured data can be improved if uncertainties of key input parameters (tortuosities, reaction kinetics, especially of clay minerals) can be reduced.

      PubDate: 2017-01-21T19:21:49Z
      DOI: 10.1016/j.pce.2017.01.004
       
  • Carbon nanotube embedded PVDF membranes: Effect of solvent composition on
           the structural morphology for membrane distillation
    • Authors: Edgar C. Mapunda; Bhekie B. Mamba; Titus A.M. Msagati
      Abstract: Publication date: Available online 12 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Edgar C. Mapunda, Bhekie B. Mamba, Titus A.M. Msagati
      Rapid population increase, growth in industrial and agricultural sectors and global climate change have added significant pressure on conventional freshwater resources. Tapping freshwater from non-conventional water sources such as desalination and waste water recycling is considered as sustainable alternative to the fundamental challenges of water scarcity. However, affordable and sustainable technologies need to be applied for the communities to benefit from the treatment of non-conventional water source. Membrane distillation is a potential desalination technology which can be used sustainably for this purpose. In this work multi-walled carbon nanotube embedded polyvinylidene fluoride membranes for application in membrane distillation desalination were prepared via non-solvent induced phase separation method. The casting solution was prepared using mixed solvents (N, N-dimethylacetamide and triethyl phosphate) at varying ratios to study the effect of solvent composition on membrane morphological structures. Membrane morphological features were studied using a number of techniques including scanning electron microscope, atomic force microscope, SAXSpace tensile strength analysis and membrane thickness, porosity and contact angle measurements. It was revealed that membrane hydrophobicity, thickness, tensile strength and surface roughness were increasing as the composition of N, N-dimethylacetamide in the solvent was increasing with maximum values obtained between 40 – 60 % N, N-dimethylacetamide. Internal morphological structures were changing from cellular structures to short finger-like and sponge-like pores and finally to large macro void type of pores when the amount of N, N-dimethylacetamide in the solvent was changed from low to high respectively. Multi-walled carbon nanotube embedded polyvinylidene fluoride membranes of desired morphological structures and physical properties can be synthesized by regulating the composition of solvents used to prepare the casting solution.

      PubDate: 2017-01-13T18:19:22Z
      DOI: 10.1016/j.pce.2017.01.003
       
  • The potential vulnerability of the Namib and Nama Aquifers due to low
           recharge levels in the area surrounding the Naukluft Mountains, SW Namibia
           
    • Authors: Winnie N. Kambinda; Benjamin Mapani
      Abstract: Publication date: Available online 11 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Winnie N. Kambinda, Benjamin Mapani
      The Naukluft Mountains in the Namib Desert are a high rainfall-high discharge area. It sees increased stream-, spring- flow as well as waterfalls during the rainy season. The mountains are a major resource for additional recharge to the Namib and Nama aquifers that are adjacent to the mountains. This paper aimed to highlight the potential vulnerability of the aquifers that surround the Naukluft Mountain area; if the strategic importance of the Naukluft Karst Aquifer (NKA) for bulk water supply becomes necessary. Chloride Mass Balance Method (CMBM) was applied to estimate rainfall available for recharge as well as actual recharge thereof. This was applied using chloride concentration in precipitation, borehole and spring samples collected from the study area. Groundwater flow patterns were mapped from hydraulic head values. A 2D digital elevation model was developed using Arc-GIS. Results highlighted the influence of the NKA on regional groundwater flow. This paper found that groundwater flow was controlled by structural dip and elevation. Groundwater was observed to flow predominantly from the NKA to the south west towards the Namib Aquifer in two distinct flow patterns that separate at the centre of the NKA. A distinct groundwater divide was defined between the two flow patterns. A minor flow pattern from the northern parts of the NKA to the north east towards the Nama Aquifer was validated. Due to the substantial water losses, the NKA is not a typical karst aquifer. While the project area receives an average rainfall of 170.36 mm/a, it was estimated that 1-14.24 % (maximum 24.43 mm/a) rainfall was available for recharge to the NKA. Actual recharge to the NKA was estimated to be less than 1-18.21 % (maximum 4.45 mm/a) reflecting the vast losses incurred by the NKA via discharge. This paper concluded that groundwater resources of the NKA were potentially finite. The possibility of developing the aquifer for bulk water supply would therefore drastically lower recharge to surrounding aquifers that sustain local populations because all received rainfall will be utilized to maximise recharge to the NKA instead of surrounding aquifers.

      PubDate: 2017-01-13T18:19:22Z
      DOI: 10.1016/j.pce.2016.12.002
       
  • Changes in ecosystem services associated with planting structures of
           cropland: a case study in Minle County in China
    • Authors: Yaqun Liu; Wei Song; Fengyun Mu
      Abstract: Publication date: Available online 11 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Yaqun Liu, Wei Song, Fengyun Mu
      The cropland ecosystem provides essential direct and indirect products and services to mankind such as food, fiber, biodiversity and soil conservation. A change of crop planting structure can change the ecosystem services of cropland by affecting land use type. In recent years, under the influence of regional comparative advantage and consumer demand changes, the crop planting structure in China has changed rapidly. However, there is still a lack of deep understanding on the effect of such a change in planting structure on the ecosystem services of cropland. Therefore, this research selected Minle County in the Heihe River Basin, which has small scattered croplands and a complex planting structure, as a study area. Based on the key time phase and optimal threshold of the normalized difference vegetation index (NDVI) data of the Thematic Mapper and Enhanced Thematic Mapper Plus (TM/ETM+) images, this study used the decision tree algorithm to classify and extract the crop planting structure in Minle County in 2007 and 2012 and to analyze the changes in its temporal and spatial patterns. Then, the market value method was adopted to estimate the effect of the change in crop planting structure on the ecosystem services of the cropland. From 2007–2012, the planting area of corn and rapeseed in Minle County increased by 5.86×103 ha and 5.10×103 ha, respectively. Conversely, the planting area of wheat and barley was reduced by 3.26×103 ha and 6.34×103 ha, respectively. These changes directly caused the increase of the ecosystem services value of corn and rapeseed by 1,062.82×104 USD and 842.54×104 USD, respectively. The resulting reduction in the ecosystem services value of wheat and barley was 488.24×104 USD and 828.29×104 USD, respectively. Besides, the total ecosystem services value of cropland increased by 1,564.98×104 USD. Further analysis found that the change in the crop planting structure caused an increase in the ecosystem services value of cropland of 359.44×104 USD, with a contribution rate of 22.97% to the total increase. The expansion of corn caused the increase of the ecosystem services value of cropland by 151.65×104 USD, with a contribution rate of 9.69% to the total increase. The change in crop planting structure in Minle County increased not only the economic benefits of crop planting, but also the ecosystem services of cropland.

      PubDate: 2017-01-13T18:19:22Z
      DOI: 10.1016/j.pce.2016.09.003
       
  • Effects of drought and salt stresses on growth characteristics of
           Euhalophyte Suaeda salsa in coastal wetlands
    • Authors: Jia Jia; Chen Huang; Junhong Bai; Guangliang Zhang; Qingqing Zhao; Xiaojun Wen
      Abstract: Publication date: Available online 4 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Jia Jia, Chen Huang, Junhong Bai, Guangliang Zhang, Qingqing Zhao, Xiaojun Wen
      The pot experiment was carried out in the Yellow River Delta to investigate the effects of drought and salt stresses on growth characteristics of Suaeda salsa, and to reveal the role of nitrogen (N) application in alleviation effects of drought and salt stresses on Suaeda salsa in coastal wetlands. In this study, plants were exposed to two water contents treatments (i.e., 14 % and 26 % water content), four salinity treatments (i.e., 2 g/kg, 4 g/kg, 6 g/kg, and 8 g/kg NaCl) and two N application treatments (i.e., 0 and 200 N mg/kg) in field conditions. Growth characteristics of Suaeda salsa were assessed as fresh weight, dry weight, height, total nitrogen (TN) and total carbon (TC). Our results showed that fresh weight, dry weight and height of Suaeda salsa promoted at lower salinity treatments but reduced at higher salinity treatments, while TN and TC contents kept stable with increasing salinity levels. Drought stress diminished the fresh weight, dry weight and height of Suaeda salsa, whereas enhanced TN contents. Under the interactive stresses of drought and salt, fresh weight and dry weight showed slight increases at lower salinity treatments, whereas decreases at higher salinity treatments. N application promoted the fresh weight, dry weight and TN contents other than the height and TC contents of Suaeda salsa. The interaction between N application and salt stress exhibited a significant influence on the fresh weight and dry weight of Suaeda salsa, whereas no significant interaction between N application and drought stress was observed. These findings of this study suggested that higher salinity, drought and the interaction of drought and higher salt stresses would retard the growth of Suaeda salsa, whereas N application could only mitigate the deleterious effects of salt stress on Suaeda salsa.

      PubDate: 2017-01-05T08:18:03Z
      DOI: 10.1016/j.pce.2017.01.002
       
  • Assessment of heavy metals contamination in soil profiles of roadside
           Suaeda salsa wetlands in the Yellow River Delta, China
    • Authors: Xiaojun Wen; Qinggai Wang; Guangliang Zhang; Junhong Bai; Wei Wang; Shui Zhang
      Abstract: Publication date: Available online 4 January 2017
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xiaojun Wen, Qinggai Wang, Guangliang Zhang, Junhong Bai, Wei Wang, Shui Zhang
      Five sampling sites (Sites A, B, C, D, and E) were selected along a 250m sampling zone covered by Suaeda salsa, which was perpendicular to a road, in the Yellow River Delta of China. Soil profile samples were collected in these five sampling sites to investigate the profile distributions and toxic risks of heavy metals. Concentrations of heavy metals (As, Cd, Cr, Cu, Ni, Pb and Zn) were determined using inductively coupled plasma atomic absorption spectrometry (ICP-AAS). The results showed that in each sampling site, Cd, Cu, Pb and Zn have approximately constant concentrations along four soil layers and did not show high contamination compared with the values of probable effect levels (PELs). All soils exhibited As and Ni pollution at all sampling sites compared with other heavy metals. The index of geo-accumulation (Igeo) values for As in the 20-30cm soil layer at Site B was grouped into Class Ⅳ(2<Igeo≤3), indicating that the soil was moderately to strongly contaminated. Forty percent of Igeo values for all soil samples for Cd were grouped into Class Ⅳ(2<Igeo≤3) and 75% samples of Site C showed moderately to strongly polluted level. The Enrichment factor (EF) values of As at Sites B, C, D, and E reached significant enrichment level and EF values of Cd at five sampling sites all reached significant enrichment level. The sum of toxic units (∑TUs) values for surface soils of Sites B and C beyond 4 indicated that Sites B and C have severer toxicity compared with other three sampling sites. As and Ni should be paid more attention to avoid potential ecotoxicity due to their high contribution ratios to the ∑TUs in this Suaeda salsa wetland. Correlation analysis (CA) and principal components analysis (PCA) revealed that Cr, Cu, Ni, Pb and Zn might derive from the common sources, Cd might originate from another, while As might have more complex sources in this study area.

      PubDate: 2017-01-05T08:18:03Z
      DOI: 10.1016/j.pce.2017.01.001
       
  • Stimulation of nitrogen turnover due to nutrients release from aggregates
           affected by freeze-thaw in wetland soils
    • Authors: Yang Song; Yuanchun Zou; Guoping Wang; Xiaofei Yu
      Abstract: Publication date: Available online 29 December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Yang Song, Yuanchun Zou, Guoping Wang, Xiaofei Yu
      The freeze-thaw phenomenon will occur more frequently in mid-high latitude ecosystems under climate change which has a remarkable effect on biogeochemical processes in wetland soils. Here, we used a wet sieving procedure and a barometric process separation (BaPS) technique to examine the responses of wetland soil aggregates and related carbon and nitrogen turnover affected by the freeze-thaw treatment. Wetland soil samples were divided into a treatment group and a control group. The treatment group was incubated at temperatures fluctuating from 10 °C to −10 °C, whereas the control group was incubated at the constant temperature of 10 °C. A 24 h process was set as the total freeze-thaw cycle, and the experiment had 20 continuous freeze-thaw cycles. In our results, the freeze-thaw process caused great destruction to the >2 mm water-stable aggregates (WSA) fraction and increased the <0.053 mm WSA fraction. The dissolved organic carbon (DOC) content was stimulated during the initial freeze-thaw cycles followed by a rapid decline, and then still increased during subsequent freeze-thaw cycles, which was mainly determined by the soil organic carbon (SOC). The NH4 + and NO3 − content, respiration rate and gross nitrification rate were all significantly improved by the freeze-thaw effect. Because the amount of NH4 + and NO3 − expressed prominent negative responses to the content of >2 mm WSA fraction and the gross nitrification rate can be stimulated at the initial freeze-thaw cycles, nutrients and substrates may play a leading role in the freeze-thaw treatment regardless of the minimal influences on microbial biomass pools.

      PubDate: 2017-01-05T08:18:03Z
      DOI: 10.1016/j.pce.2016.12.005
       
  • Impacts of sea cucumber farming on biogeochemical characteristics in the
           Yellow River estuary, Northern China
    • Authors: Jing Fu; Hisashi Yokoyama; Baoshan Cui; Jin Zhou; Jiaguo Yan; Xu Ma; Shozo Shibata
      Abstract: Publication date: Available online 28 December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Jing Fu, Hisashi Yokoyama, Baoshan Cui, Jin Zhou, Jiaguo Yan, Xu Ma, Shozo Shibata
      To investigate the potential environmental effects of pond farming for Apostichopus japonicas in Yellow River estuary, we examined discrepancies of distance-based typical pollution indicators (TOC, TN, NO3 -, NH4 +, NO2 - and PO4 3-) and biochemical tracers (δ13C and δ15N) in water column and sediment, as well as dietary characteristics of dominant macrobenthos between farming and non-farming areas. The results revealed that studied variables in water column showed no uniform spatial differences. Meanwhile, those in sediments displayed similar decrease tendencies from farming pond to the adjacent tidal flat, which was considered to represent the environmental effects of farming. Biochemical tracers (δ13C and δ15N) in both water column and sediment confirmed the origin of organic matters from the aquaculture waste. The detectable dispersion distance of aquaculture waste was restricted to an area within 50 m distance as determined by most variables in sediment (TOC, TN, NO3 - and NH4 +), particularly by C/N ratio and δ13C with which origins of the wastes were traced. Bayesian mixing models indicated that in the farming area BMA had a larger contribution, while POM(marine) showed a smaller contribution to the diets of Helice tridens and Macrophthalmus abbreviates compared to those in the non-farming area. The overall results showed that pond farming for Apostichopus japonicus in the Yellow River estuary altered the local environment to a certain extent. For methodological consideration, sediment biogeochemical characteristics as a historical recorder much more effectively reflected aquaculture waste accumulation, and stable isotope approaches are efficient in tracing the origin and extent of various allogenous sources.

      PubDate: 2017-01-05T08:18:03Z
      DOI: 10.1016/j.pce.2016.12.006
       
  • Measuring environmental performance of industrial sub-sectors in China: a
           stochastic metafrontier approach
    • Authors: Yuping Bai; Xiangzheng Deng; Qian Zhang; Zhan Wang
      Abstract: Publication date: Available online 28 December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Yuping Bai, Xiangzheng Deng, Qian Zhang, Zhan Wang
      In this paper, we quantitatively measure the environmental performance and potential capacities of carbon emission mitigation of 39 industrial sectors in China during 2005-2011 by adopting a stochastic metafrontier approach. We also analyze the differences of environmental performance and technology gap ratios (TGRs) across three categorized industrial groups. Cluster analysis of carbon intensity provides the categorized groups. The results show that due to neglect of technology gaps among the categorized groups, the environmental performance measured by a stochastic frontier approach (SFA) is underestimated. Comparison analysis infers that, relative to the metafrontier, the industrial sectors in Group 1 achieve the highest environmental performance and TGRs, while environmental performance and TGRs of industrial sectors in Group 3 is still at a low level for lack of advanced production technology. Industrial sectors also perform significant differences on potential capacities of carbon emission mitigation. We suggest that policies and regulations on industrial technology innovation and control of carbon emissions should be strengthened for eco-efficient and sustainable development.

      PubDate: 2017-01-05T08:18:03Z
      DOI: 10.1016/j.pce.2016.12.007
       
  • Hydrochemical modelling of water quality in terms of emerging
           micropollutants in Mpumalanga, Gauteng and North West Provinces
    • Authors: Elijah M.M. Wanda; Bhekie B. Mamba; Titus A.M. Msagati
      Abstract: Publication date: Available online 26 December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Elijah M.M. Wanda, Bhekie B. Mamba, Titus A.M. Msagati
      Emerging micropollutants (EMPs) are ubiquitous in aquatic systems and are associated with a wide range of eco-toxicological effects worldwide. There remains a lack of scientific understanding of the major underlying hydrochemical factors behind variations in concentration heterogeneities of EMPs in time and space. This study was therefore conducted to determine major hydrochemical processes controlling water quality and the occurrence of EMPs mainly, carbamazepine (CBZ), tonalide (AHTN), galaxolide (HHCB), caffeine (CAF), technical 4-nonylphenol (NP) and bisphenol A (BPA) in water from Mpumalanga, Gauteng and North West Provinces in South Africa. Grab water samples were collected bi-monthly between June 2014 and April 2016 from 44 water sources using standard sampling procedures. BPA, NP, CAF, HHCB, AHTN, CBZ were extracted, cleaned and enriched using autotrace-SPE at neutral pH and analyzed using GC × GC-TOFMS. Kruskal Wallis-test was used to test for temporal variations in occurrence of the analytes. The Geochemist's Workbench® Release 11 software, Surfer Golden Graphics for surface mapping, PHREEQC software and bivariate ion plots were used determine the major hydrogeochemical processes. The mean concentrations of EMPs varied from 3.48 μg/L for CAF to 421.53 μg/L for HHCB. Although the Kruskal Wallis test revealed no any statistically significant temporal variations in concentrations of the analytes in water samples at 95% confidence level, their occurrence and distribution vary spatially with BPA being the most widely distributed EMP and was present in 62% of the sampled sites. Municipal waste water inputs, agricultural pollution, ion-exchange reactions, carbonate and silicate weathering were the major processes controlling water quality in the study area. This study may assist water resource managers to ably address and manage water pollution resulting from a number of natural and anthropogenic hydrochemical processes in the study area.

      PubDate: 2017-01-05T08:18:03Z
      DOI: 10.1016/j.pce.2016.12.004
       
  • Detrimental effects of commercial zinc oxide and silver nanomaterials on
           bacterial populations and performance of wastewater systems
    • Authors: Anza-vhudziki Mboyi; Ilunga Kamika; MaggyN.B. Momba
      Abstract: Publication date: Available online 26 December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Anza-vhudziki Mboyi, Ilunga Kamika, MaggyN.B. Momba
      The widespread use of commercial nanomaterials (NMs) in consumer products has raised environmental concerns as they can enter and affect the efficiency of the wastewater treatment plants. In this study the effect of various concentrations of zinc oxide NMs (nZnO) and silver NMs (nAg) on the selected wastewater bacterial species (Bacillus licheniformis, Brevibacillus laterosporus and Pseudomonas putida) was ascertained at different pH levels (pH 2, 7 and 10). Lethal concentrations (LC) of NMs and parameters such as chemical oxygen demand (COD) and dissolved oxygen (DO) were taken into consideration to assess the performance of a wastewater batch reactor. Bacterial isolates were susceptible to varying concentrations of both nZnO and nAg at pH 2, 7 and 10. It was found that a change in pH did not significantly affect the toxicity of test NMs towards target bacterial isolates. All bacterial species were significantly inhibited (p < 0.05) in the presence of 0.65 g/L of nZnO and nAg. In contrast, there was no significant difference (p > 0.05) in COD removal in the presence of increasing concentrations of NMs, which resulted in increasing releases of COD. Noticeably, there was no significant difference (p > 0.05) in the decrease in DO uptake in the presence of increasing NM concentrations for all bacterial isolates. The toxic effects of the target NMs on bacterial populations in wastewater may negatively impact the performance of biological treatment processes and may thus affect the efficiency of wastewater treatment plants in producing effluent of high quality.

      PubDate: 2017-01-05T08:18:03Z
      DOI: 10.1016/j.pce.2016.12.003
       
  • Water productivity and integrated water resources management
    • Authors: Xiangzheng Deng; R.B. Singh; Junguo Liu; Burak Güneralp
      First page: 1
      Abstract: Publication date: December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 96
      Author(s): Xiangzheng Deng, R.B. Singh, Junguo Liu, Burak Güneralp


      PubDate: 2016-12-04T02:21:53Z
      DOI: 10.1016/j.pce.2016.11.002
      Issue No: Vol. 96 (2016)
       
  • Strategy for management of lake-catchment system integrated with natural
           and anthropogenic factors in China
    • Authors: Zhandong Yang; Feng Wu; Xing Gao
      Pages: 26 - 33
      Abstract: Publication date: December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 96
      Author(s): Zhandong Yang, Feng Wu, Xing Gao
      Lake eutrophication that has caused severe damages to aquatic ecosystems is a hot issue in the field of water pollution control, so analyzing its process and driving mechanism is of great significance. In this study, we detected its major driving factors based on an observed dataset and assessed the impacts of these factors. Firstly, empirical econometric models were used to ascertain the Per capita GDP and the percentage of impervious surface, which are significantly related with the eutrophication level. Eutrophication is slightly affected by anthropogenic disturbance, but is negatively related to the supply coefficient. Secondly, all driving factors are divided into two categories, including the stresses caused by human activities and the comprehensive health status, which are expressed as the two coordinate axes of an indicator-matrix. Thirdly, lake classification, which is a decision-making tool for management and control of eutrophication, suggests a breakdown in communication between researchers and water managers. Finally, corresponding management strategies are recommended, and the classification system can be used to simplify management by grouping lakes that may be managed by similar strategies. The classification management may enlighten and guide the appropriate policy implementation for lake eutrophication management.

      PubDate: 2016-12-04T02:21:53Z
      DOI: 10.1016/j.pce.2016.06.006
      Issue No: Vol. 96 (2016)
       
  • The sustainability of drinking water supply in rural China: Does the
           provision of drinking water investment mismatch the demand of residents?
    • Authors: Ying Liu; Tang Yao; Yunli Bai; Yu Liu
      Pages: 34 - 40
      Abstract: Publication date: December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 96
      Author(s): Ying Liu, Tang Yao, Yunli Bai, Yu Liu
      It is doubted that the top down nature of investment planning may lead to mismatches between drinking water investment and the demands of local residents in rural China. Statistical and econometric analysis based on data of 2020 rural households from five Chinese provinces from 1998 to 2011 are used to illustrate the linkage between demand for drinking water investment and construction of drinking water projects. Household's demand significantly affects drinking water projects implemented by upper level governments and implemented jointly, but is not significant in explaining the projects implemented by village. There is evidence to suggest that the demands of local leaders override those of households in the implementation of drinking water projects provided by village in the early stage of 2005–2008. The situation improves in the latter stage of 2008–2011when the village level participatory bodies begin to provide opportunities for households to voice their preferences on public goods investment. The results of this study imply that it is important to explore appropriate regulations and policies that enabling local cadres to better meet local demands of their communities to ensure the sustainability of rural drinking water supply.

      PubDate: 2016-12-04T02:21:53Z
      DOI: 10.1016/j.pce.2016.07.002
      Issue No: Vol. 96 (2016)
       
  • Long time-series spatiotemporal variations of NPP and water use efficiency
           in the lower Heihe River Basin with serious water scarcity
    • Authors: Haiming Yan; Jinyan Zhan; Huicai Yang; Fan Zhang; Guofeng Wang; Wenjie He
      Pages: 41 - 49
      Abstract: Publication date: December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 96
      Author(s): Haiming Yan, Jinyan Zhan, Huicai Yang, Fan Zhang, Guofeng Wang, Wenjie He
      It is of great significance to analyze the long time-series spatiotemporal dynamics of water use efficiency (WUE) to formulating appropriate management measures in response to the growing water scarcity in arid and semi-arid regions. This study analyzed the long time-series variations of WUE in the Lower Heihe River Basin, a typical arid and semi-arid region in China. The net primary productivity (NPP) was first estimated with the C-fix model, then WUE during 2001–2010 was calculated with the NPP and evapotranspiration (ET) data, and the accumulative WUE was further calculated. The results showed that the annual NPP and WUE in the study area ranged from zero to 448.70 gC/(m2 a) and from zero to 2.20 gC kg−1 H2O, respectively, both of which showed an overall increasing trend during 2001–2010. Besides, the spatial pattern of WUE kept overall unchanged during 2001–2010, but with remarkable change in some part of the study area. In addition, the accumulative WUE of the whole study area showed a first sharply decreasing and then gradually increasing trend, but there was still some scope to improve the WUE, and it is necessary to carry out some more specific policies to further improve the water allocation and WUE within the Lower Heihe River Basin. Although with some uncertainties, these results still can provide valuable reference information for improving the water resource management and ecological conservation to guarantee provision of essential ecosystem services in arid and semi-arid regions.

      PubDate: 2016-12-04T02:21:53Z
      DOI: 10.1016/j.pce.2016.06.003
      Issue No: Vol. 96 (2016)
       
  • Allocating agricultural production factors: A scenario-based modeling of
           wheat production in Shandong Province, China
    • Authors: Fan Zhang; Jinyan Zhan; Qian Zhang; Haiming Yan; Zhongxiao Sun
      Pages: 55 - 63
      Abstract: Publication date: December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 96
      Author(s): Fan Zhang, Jinyan Zhan, Qian Zhang, Haiming Yan, Zhongxiao Sun
      We aim to determine the effects of agricultural factors input per hectare on wheat production, and to optimize the allocation of wheat production factors under three scenarios and in different operating modes. Data were collected from 204 farming households using a face-to-face questionnaire. The sampled farms were selected through a stratified random sampling technique. We find fertilizer cost, irrigation cost and machinery cost all positively and significantly affect the per-unit-area wheat production, indicating the labor cost is not the major driving factor on wheat yield increment. Multi-object optimization model is used to allocate the production factors per hectare. We find under the Business as usual (BAU) scenario, the irrigation cost per-hectare wheat production after optimization in 2014 grows at a rate of 24.31% and accounts for 14.9% of total input. Under the Cooperate Environmental Sustainability (CES) scenario, the fertilizer and pesticide costs after optimization drop significantly by 42.83% and 21.41%, respectively. Under the Rapid Benefit Growth (RBG) scenario, the irrigation cost after optimization increase by 2.56% and the fertilizer cost increases by 4.69% compared with the surveyed data. Comparison of optimized data among three operating modes shows that the labor costs at household farm and cooperative farm both increase significantly. Cooperative farms are more successful in production factor use efficiency and economic performance. In conclusion, wheat production at different operating modes could be improved so as to constitute more efficient and economic use of production factors.

      PubDate: 2016-12-04T02:21:53Z
      DOI: 10.1016/j.pce.2016.06.002
      Issue No: Vol. 96 (2016)
       
  • The impact of land use change on water balance in Zhangye city, China
    • Authors: Zhongxiao Sun; Feng Wu; Chenchen Shi; Jinyan Zhan
      Pages: 64 - 73
      Abstract: Publication date: December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 96
      Author(s): Zhongxiao Sun, Feng Wu, Chenchen Shi, Jinyan Zhan
      Land use change has a significant effect on water balance, especially in arid region, such as Northwest China. In this paper, we analyze the effect of land use change on water balance in terms of the amount of water supply and demand from economic perspective. It's the first time to extend the basic 48 sectors input-output table to include water and land accounts that involved into multiple production processes for Zhangye city. We then perform the improved ORANI-G model, a single region Computable General Equilibrium (CGE) model, to analyze the effect of land use change on water balance under three scenarios. Subsequently, scenario-based simulation results are interpreted through selected sectors from agricultural, industrial, and service sectors respectively. Finally, the effect of land use change on water balance is analyzed through the difference between business-as-usual and land use unchanged scenarios. The results show that the extent of effect on water balance is different among sectors. Specifically, from the perspective of absolute value, service sectors are the largest, followed by industrial sectors, and the agricultural sectors are the least. Conversely, in terms of percentage change of land use, the largest extent of effect occurs in agricultural sectors. Additionally, with the rapid urbanization and the development of social economy, water balance in industrial sectors and service sectors will be stricken and reconstructed to a new high level. Simulation results also show that agricultural land shrinking will mitigate water scarcity distinctly, which indicates that balance the relationship among different stakeholders is imperative to guarantee water transformation from agricultural sectors to industrial and service sectors.

      PubDate: 2016-12-04T02:21:53Z
      DOI: 10.1016/j.pce.2016.06.004
      Issue No: Vol. 96 (2016)
       
  • Retraction notice to “Status of groundwater arsenic pollution in
           Holocene aquifers from parts of the Ghaghara Basin, India: Its relation to
           geomorphology and hydrogeological setting”[Phys. Chem. Earth 58–60C
           (2013) 68–76]
    • Authors: Babar Ali Shah
      First page: 84
      Abstract: Publication date: December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C, Volume 96
      Author(s): Babar Ali Shah


      PubDate: 2016-12-04T02:21:53Z
      DOI: 10.1016/j.pce.2015.02.001
      Issue No: Vol. 96 (2016)
       
  • Rethinking the role of edaphic condition in halophyte vegetation
           degradation on salt marshes due to coastal defense structure
    • Authors: Tian Xie; Baoshan Cui; Junhong Bai; Shanze Li; Shuyan Zhang
      Abstract: Publication date: Available online 9 December 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Tian Xie, Baoshan Cui, Junhong Bai, Shanze Li, Shuyan Zhang
      Determining how human disturbance affects plant community persistence and species conservation is one of the most pressing ecological challenges. The large-scale disturbance form defense structures usually have a long-term and potential effect on phytocommunity in coastal saltmarshes. Coastal defense structures usually remove the effect of tidal wave on tidal salt marshes. As a consequence, edaphic factors such as the salinity and moisture contents are disturbed by tidal action blocking. However, few previous studies have explicitly addressed the response of halophyte species persistence and dynamics to the changing edaphic conditions. The understanding of the response of species composition in seed banks and aboveground vegetation to the stress is important to identify ecological effect of coastal defense structures and provide usefully insight into restoration. Here, we conducted a field study to distinguish the density, species composition and relationships of seed bank with aboveground vegetation between tidal flat wetlands with and without coastal defense structures. We also addressed the role of edaphic condition in vegetation degradation caused by coastal defense structures in combination with field monitor and greenhouse experiments. Our results showed the density of the seed bank and aboveground vegetation in the tidal flat without coastal defense structures was significantly lower than the surrounded flat with coastal defense structures. A total of 14 species were founded in the surrounded flat seed bank and 11 species in the tidal flat, but three species were only recorded in aboveground vegetation of the tidal flat which was much lower than 24 aboveground species in the surrounded flat. The absent of species in aboveground vegetation contributed to low germination rate which depend on the edaphic condition. The germination of seeds in the seed bank were inhabited by high soil salinity in the tidal flat and low soil moisture in the surrounded flat. Our study supported the hypothesis that the change of edaphic condition caused by coastal defense structures was the main reason for the difference of the species composition similarity between aboveground vegetation and the soil seed bank between the tidal and surrounded flats. Therefore, mitigating the hydrological disturbance and maintaining the original state of edaphic factors would be useful implications for reducing the ecological effect of defense structure to vegetation communities in coastal salt marshes.

      PubDate: 2016-12-11T03:02:56Z
      DOI: 10.1016/j.pce.2016.12.001
       
  • Heavy metals pollution in soil profiles from seasonal-flooding riparian
           wetlands in a Chinese Delta: Levels, distributions and toxic risks
    • Authors: Guangliang Zhang; Junhong Bai; Qingqing Zhao; Jia Jia; Xiaojun Wen
      Abstract: Publication date: Available online 29 November 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Guangliang Zhang, Junhong Bai, Qingqing Zhao, Jia Jia, Xiaojun Wen
      Soil profile samples were collected in seasonal-flooding riparian wetlands in the Yellow River Delta (YRD) of China in autumn and spring to investigate the levels, distributions and toxic risks of heavy metals in soil profiles. Total elemental contents of Al, As, Cd, Cr, Cu, Ni, Pb and Zn were determined using inductively coupled plasma atomic absorption spectrometry (ICP-AAS). Results indicated that the contents of determined heavy metals showed non-negligible depth variations (coefficient of variation > 10%), and their distribution patterns were irregular. Compared with other heavy metals, both As and Cd presented higher enrichment factors (EF) based on the classification of EF values (moderate enrichment for As while significant enrichment for Cd). Cluster analysis (CA) and principal components analysis (PCA) revealed that Cr, Cu, Ni, Pb and Zn might derive from the common source, while As and Cd shared another similar source. The toxic unit (TU) values of these heavy metals did not exceed probable effect levels (PEL) except for Ni. Both As and Ni showed higher contributions to the sum of TU (∑TUs), which indicated they were the primary concerns of heavy metals pollution. Generally, As, Cd and Ni should be paid more attention for wetlands managers and policy makers to avoid potential ecotoxicity in the study area. The findings of this study could contribute to the prevention and control of heavy metals pollution in estuarine wetlands.

      PubDate: 2016-12-04T02:21:53Z
      DOI: 10.1016/j.pce.2016.11.004
       
  • Seasonal variation in pans in relation to limno-chemistry, size,
           hydroperiod, and river connectivity in a semi-arid subtropical region
    • Authors: Tamuka Nhiwatiwa; Tatenda Dalu
      Abstract: Publication date: Available online 24 November 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Tamuka Nhiwatiwa, Tatenda Dalu
      Seasonal pans are hydrologically dynamic, with significant changes in water volume and depth in response to high evaporation, infiltration rates and inundation events. Intra-seasonal and inter-seasonal changes in endorheic and floodplain pans in relation to limnology, size, hydroperiod, and river connectivity were studied over two rainfall seasons across 36 pans at the Save Valley Conservancy. In the study region, floodplain pans were identified as pans that had connectivity with the Save River, while the endorheic pans (large and small) were hydrologically isolated basins. Seasonal trends for physico-chemical variables were initial low and gradual increased for both rainfall seasons. Significant inter-seasonal differences for several physico-chemical variables were observed. No significant differences in physico-chemical variables were observed between large and small endorheic pans, with the except for vegetation cover, which was higher in large pans. Floodplain pans differed from the endorheic systems in pH, conductivity, nutrients and suspended solids. Connectivity was found to be insignificant, as connections between these systems were probably too infrequent. Seasonal pans were uniquely distinguished by their morphometric, physico-chemical and hydrological characteristics. Inevitably, they are vulnerable to climate change with the extent of their resilience currently unknown.

      PubDate: 2016-11-27T15:42:03Z
      DOI: 10.1016/j.pce.2016.11.003
       
  • Living with floods – household perception and satellite observations in
           the Barotse Floodplain, Zambia
    • Authors: Xueliang Cai; Alemseged Haile; James Magidi; Everisto Mapedza; Luxon Nhamo
      Abstract: Publication date: Available online 11 November 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Xueliang Cai, Alemseged Haile, James Magidi, Everisto Mapedza, Luxon Nhamo
      The Barotse Floodplain, a designated Ramsar site, is home to thousands of indigenous people along with an extensive wetland ecosystem and food production system. Increasingly it is also a popular tourist destination with its annual Kuomboka festival which celebrates the relocation of the king and the Lozi people to higher ground before the onset of the flood season. This paper presents an integrated approach which cross validates and combines the floodplain residents’ perceptions about recent floods with information on flood inundation levels derived from satellite observations. Local residents’ surveys were conducted to assess farmers’ perception on the flooding patterns and the impact on their livelihoods. Further, a series of flood inundation maps from 1989 to 2014 generated from remotely sensed Landsat imagery were used to assess the recent patterns of floods. Results show that the floodplain has a population of 33 thousand living in 10849 small permeant or temporary buildings with a total cropland area of 4976 ha. The floodplain hydrology and flooding patterns have changed, confirmed by both surveys and satellite image analysis, due to catchment development and changing climate. The average annual inundated areas have increased from about 316 thousand ha in 1989-1998 to 488 thousand ha in 2005-2014. As a result the inundated cropland and houses increased from 9% and 6% in 1989 to 73% and 47% in 2014, respectively. The timing of the floods has also changed with both delaying and early onset happening more frequently. These changes cause increasing difficulties in flood forecast and preparation using indigenous knowledge, therefore creating greater damages to crops, livestock, and houses. Current floodplain management system is inadequate and new interventions are needed to help manage the floods at a systematic manner.

      PubDate: 2016-11-13T15:32:01Z
      DOI: 10.1016/j.pce.2016.10.011
       
  • Impact of salinity and Pb on enzyme activities of a saline soil from the
           Yellow River delta: A microcosm study
    • Authors: Lidi Zheng; Mingxiang Zhang; Rong Xiao; Jingxiao Chen; Feihai Yu
      Abstract: Publication date: Available online 11 November 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Lidi Zheng, Mingxiang Zhang, Rong Xiao, Jingxiao Chen, Feihai Yu
      Soil enzyme activities are sensitive to the changes of soil properties and pollutants. In this study, the influence of salinity and Pb on the soil enzyme (catalase, CAT; invertase, IA; urease, UA) activities regarding the soil aggregate size classes was investigated. We selected a saline soil from the Yellow River delta, and adopted an orthogonal experiment designed with five Pb concentration levels and five salinity levels. The soil was dry sieved into three soil aggregate size classes: >2000 μm, 250–2000 μm, and <250 μm. All three enzyme activities significantly decreased with the increase of soil salinity (P < 0.05). Pb had an inhibition effect on IA and UA activities but a significant promoting effect on CAT activity (P < 0.05) within the concentration range of 0–400 mg kg−1. When Pb concentration exceeded 400 mg kg−1, with the increase of Pb concentration, there were no significant changes of all the enzyme activities under the inhibition or promotion effects of Pb. The Pb concentration which leads to a significant reduction is between 0 and 200 mg kg−1 for IA activity and 200–400 mg kg−1 for UA activity. And the increase of soil salinity led to a higher toxicity of Pb for UA activity. The toxicity range could be a valid reference for the formulation of soil quality standards in estuarine wetlands. We concluded that the effects of Pb on soil enzyme activities depend on the Pb concentration, soil salinity and the enzyme types. IA activity showed a higher activity in the macro-aggregate (250–2000 μm), while there was no significant difference in CAT and UA activities among three particle size classes. Since the IA activity was sensitive to soil salinity, Pb concentration and soil aggregate size, it could be selected as a representative indicator for soil monitoring in the Yellow River delta.

      PubDate: 2016-11-13T15:32:01Z
      DOI: 10.1016/j.pce.2016.11.001
       
  • Electrospun polyacrylonitrile nanofibers functionalized with EDTA for
           adsorption of ionic dyes
    • Authors: E.F.C. Chaúque; J.C. Ngila; Adedeji A. Adelodun; C.J. Greyling; L.N. Dlamini
      Abstract: Publication date: Available online 1 November 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): E.F.C. Chaúque, J.C. Ngila, Adedeji A. Adelodun, C.J. Greyling, L.N. Dlamini
      The manipulation of nanofibers’ surface chemistry could enhance their potential application toward the removal of ionic dyes in wastewater. For this purpose, surface modification of electrospun polyacrylonitrile (PAN) nanofibers with ethylenediaminetetraacetic acid (EDTA) and ethylenediamine (EDA) crosslinker was experimented. The functionalized EDTA-EDA-PAN nanofibers were characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) technique. The impregnation of EDA and EDTA chelating agents on the surface of PAN changed the distribution of nanofibers as proximity is increased (accompanied by reduced softness), but the nanofibrous structure of the pristine PAN nanofibers was not substantially altered. Adsorption equilibrium studies were performed with Freundlich, Langmuir and Temkin isotherm models with the former providing better correlation to the experimental data. The modified PAN nanofibers showed efficient sorption of methyl orange (MO) and reactive red (RR) from aqueous synthetic samples, evinced by the maximum adsorption capacities (at 25 ºC) of 99.15 and 110.0 mg g-1, respectively. The fabricated nanofibers showed appreciable removal efficiency of the target dye sorptives from wastewater. However, the presence of high metal ions content affected the overall extraction of dyes from wastewater due to the depletion of the adsorbent´s active adsorptive sites.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.10.008
       
  • Modelling phytoremediation of nitrogen-polluted water using water hyacinth
           (Eichhornia crassipes)
    • Authors: Aloyce W. Mayo; Emmanuel E. Hanai
      Abstract: Publication date: Available online 30 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Aloyce W. Mayo, Emmanuel E. Hanai
      Water hyacinth (Eichhornia crassipes) has a great potential for purification of wastewater through physical, chemical and biological mechanisms. In an attempt to improve the quality of effluents discharged from waste stabilization ponds at the University of Dar es Salaam, a pilot plant was constructed to experiment the effectiveness of this plants for transformation and removal of nitrogen. Samples of wastewater were collected and examined for water quality parameters, including pH, temperature, dissolved oxygen, and various forms of nitrogen, which were used as input parameters in a kinetic mathematical model. A conceptual model was then developed to model various processes in the system using STELLA 6.0.1 software. The results show that total nitrogen was removed by 63.9%. Denitrification contributed 73.8% of the removed nitrogen. Other dominant nitrogen removal mechanisms are net sedimentation and uptake by water hyacinth, which contributed 16.7% and 9.5% of the removed nitrogen, respectively. The model indicated that in presence of water hyacinth biofilm about 1.26 g Nm-2day-1 of nitrogen was removed. However, in the absence of biofilm in water hyacinth pond, the permanent nitrogen removal was only 0.89 g Nm-2day-1. This suggests that in absence of water hyacinth, the efficiency of nitrogen removal would decrease by 29.4%.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.10.016
       
  • Development of probabilistic operating rules for Hluhluwe Dam, South
           Africa
    • Authors: J. Ndiritu; J. Odiyo; R. Makungo; B. Mwaka; N. Mthethwa; C. Ntuli; A. Andanje
      Abstract: Publication date: Available online 30 October 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): J. Ndiritu, J. Odiyo, R. Makungo, B. Mwaka, N. Mthethwa, C. Ntuli, A. Andanje
      Hluhluwe Dam, with a 30 million m3 reservoir that supplies water for irrigation and Hluhluwe municipality in Kwa-Zulu Natal Province, South Africa, was consistently experiencing low storage levels over several non-drought years since 2001. The dam was operated by rules of thumb and there were no records of water releases for irrigation - the main user of the dam. This paper describes an assessment of the historic behaviour of the reservoir since its completion in 1964 and the development of operating rules that accounted for: i) the multiple and different levels of reliability at which municipal and irrigation demands need to be supplied, and ii) inter-annual and inter-decadal variability of climate and inflows into the dam. The assessment of the behaviour of the reservoir was done by simulation assuming trigonometric rule curves that were optimized to maximize both yield and storage state using the SCE-UA method. The resulting reservoir behaviour matched the observed historic trajectory reasonably well and indicated that the dam has mainly been operated at a demand of 10 million m3/year until 2000 when the demand suddenly rose to 25 million m3/year. Operating rules were developed from a statistical analysis of the base yields from 500 simulations of the reservoir each using 5 year-long stochastically generated sequences of inflows, rainfall and evaporation. After the implementation of the operating rules in 2009, the storage state of the dam improved and matched those of other reservoirs in the region that had established operating rules.

      PubDate: 2016-11-06T15:24:23Z
      DOI: 10.1016/j.pce.2016.10.017
       
  • Water Ecological Function Zoning in Heihe River Basin, Northwest China
    • Authors: Dongdong Chen; Gui Jin; Qian Zhang; Aisha Olushola Arowolo; Yifan Li
      Abstract: Publication date: Available online 7 September 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Dongdong Chen, Gui Jin, Qian Zhang, Aisha Olushola Arowolo, Yifan Li
      Rapid urbanization coupled with increase in population growth rate in recent years has accelerated economic pressure on the ecological environment leading to a gradual deterioration of global and regional environment. This has particularly resulted into water contamination and shortage of water resources thus posing a great threat to human survival. How to guaranteeing sustainable use of basin water resources has attracted more and more attentions. The Heihe River Basin is the secondary longest river inland China and the significantly water source of Hexi Corridor, the problem of water pollution, ecological environment deterioration and the shortage of water has seriously threatened the ecological system of the Heihe River Basin. In this study, through depicting the characteristics of natural environment, human activities, water ecosystem services and other factors in Heihe River Basin we delineated the water ecological function in Heihe River using the principal components analysis and the K-means clustering method. In the study, Heihe river Basin is divided into 3 primary level areas and 8 secondary level sub-areas. Water ecological characteristics analysis showed that the spatial distribution of the water ecological function of Heihe River Basin was not uniform, which are mainly showed in three aspects, function of windproof and sand fixation, function of soil erosion prevention and function of water sources conservation. The results of this study can provide effective and scientific theoretical references for the integrated water sources management and the ecological function optimization of the Heihe River Basin.

      PubDate: 2016-09-08T13:56:03Z
      DOI: 10.1016/j.pce.2016.08.005
       
  • Modelling analysis of water-use efficiency of Maize in Heihe river basin
    • Authors: Guofeng Wang; Jiancheng Chen; Qing Zhou; Xi Chu; Xiaoxue Zhou
      Abstract: Publication date: Available online 6 September 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Guofeng Wang, Jiancheng Chen, Qing Zhou, Xi Chu, Xiaoxue Zhou


      PubDate: 2016-09-08T13:56:03Z
      DOI: 10.1016/j.pce.2016.08.010
       
  • A Method to Correct Eddy Covariance Flux Underestimates under an Advective
           Environment for Arid or Semi-arid Regions
    • Authors: Hongbo Su; Yongmin Yang; Lina Xu; José L. Chávez; Steven R. Evett; Terry A. Howell; Jing Tian; Shaohui Chen; Jinyan Zhan
      Abstract: Publication date: Available online 31 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Hongbo Su, Yongmin Yang, Lina Xu, José L. Chávez, Steven R. Evett, Terry A. Howell, Jing Tian, Shaohui Chen, Jinyan Zhan
      Water scarcity is one of the main factors limiting agricultural development in arid or semi-arid areas. Accurate Evapotranspiration (ET) observations and estimations are crucial in water cycle studies to estimate water losses from the terrestrial surfaces to the atmosphere to close the regional water budget. The eddy covariance (EC) method is an important technique measure ET and other land surface energy fluxes. However, the underestimation of energy fluxes and the problem of EC energy balance non-closure are far from solved. In this study, a new method is proposed to account for advection in order to correct EC data under advective environments. This advection based method was applied to data from Bushland, TX, which is subject to dry air and strong winds. Observations from two identical EC systems as well as two precision monolithic weighing lysimeters were used in this analysis. Both EC sites showed significant underestimates of evapotranspiration (ET) compared with lysimeter measurements. The daily energy balance closure for NE01 and SE02 sites were 0.78 and 0.74 respectively. The advection correction method provided improved performance in daytime, and it is more suitable for ET estimate than forcing closure under the advective environment. For nighttime, two methods (NCM1 and NCM2) were proposed to correct EC underestimates. Finally, all the corrected ET values were compared with the lysimeter measurements. For NE01 site, the MAD (mean absolute deviation) and the RMSD (root mean square deviation) were 47.72 W/m2 and 67.66 W/m2, respectively; and the r2 (coefficient of determination) was 0.85. For SE02 site, the MAD and RMSD were 30.59 W/m2 and 44.43 W/m2; and the r2 was 0.93. The statistical measures illustrated that the proposed methods are functional and appropriate under an advective environment. The accurate estimate of actual evapotranspiration will benefit both the strategic planning of optimal water uses and the improved understanding the environmental and hydrological processes.

      PubDate: 2016-09-03T13:21:07Z
      DOI: 10.1016/j.pce.2016.08.009
       
  • Forecast and optimal allocation of production, living and ecology water
           consumption in Zhangye, China
    • Authors: Qian Xu; Wei Song; Ying Zhang
      Abstract: Publication date: Available online 6 August 2016
      Source:Physics and Chemistry of the Earth, Parts A/B/C
      Author(s): Qian Xu, Wei Song, Ying Zhang
      The water crisis is one of three crises that are persecuting the world. China is among the countries that face severe water shortages. Water scarcity and water pollution have seriously affected China's sustainable development in terms of the economy and society. Water resources per capita of China is only one quarter of the world's average. In addition, about 70 percent of China’s rivers, lakes, and reservoirs are affected by pollution. Due to limited water resources, a crucial issue for the sustainable development of the watershed is how to resolve the human/nature competition for water and how to achieve the coordinated development of the economy, society and ecology. On the basis of defining water consumption for production, living and ecology (WPLE), this paper proposes a framework for forecasting and optimally allocating WPLE. Using Zhangye, in the middle reaches of the Heihe River Basin as the case study area, we forecasted and optimally allocated WPLE under three development scenarios, i.e. the conventional development scenario (CDS), the economy-priority development scenario (EPDS) and the environmentally sustainable development scenario (ESDS). In 2010, the proportions of WPLE in Zhangye were 87.73%, 2.74% and 9.53%, respectively. In 2020, the proportions of WPLE will be 74.80%, 4.50% and 20.70% under the CDS, 76.16%, 5.27% and 18.57% under the EPDS, and 74.99%, 4.51% and 20.50% under the ESDS. In the future, the proportion of production water consumption of Zhangye will drastically decrease, while the proportion of ecological water consumption will significantly increase. The main contradiction of the co-evolution of WPLE of Zhangye is the competitiveness of production and living water consumption with ecological water consumption.

      PubDate: 2016-08-10T11:13:00Z
      DOI: 10.1016/j.pce.2016.07.003
       
 
 
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