Green and Eco‐Friendly Removal of Mycotoxins with Organo‐Bentonites; Isothermal,Kinetic, and Thermodynamic Studies

In the current study the application of organo‐modified bentonite for the adsorption of mycotoxins (aflatoxin B1, citrinin, patulin, and zearalenone) is presented. The modification of clays is carried out using benzyl‐tri‐n‐butyl ammonium bromide (BTB), benzethonium chloride (BTC), and dioctyl sodium sulfosuccinate (DSS). Various experimental parameters such as pH, time, adsorbent dose, and mycotoxins concentration are thoroughly studied. The modified clays (B‐BTB, B‐BTC and B‐DSS) are characterized by X‐ray fluorescence, X‐ray diffraction, and Fourier transform infrared spectroscopy. The results depicted the high detoxification efficiency (≈99%) of modified clays for the removal of mycotoxins under optimized conditions (pH 5, time: 30 min, adsorbent amount: 50 mg). The adsorption capacities of modified clays are found in the order of: B‐BTC (AFB1: 18.02, CIT: 18.35, PAT: 18.21, ZEA: 18.09 mg g^?1) > B‐BTB (AFB1: 17.7, CIT: 18.11, PAT: 17.95, ZEA: 17.90 mg g^?1) > B‐DSS (AFB1: 17.5, CIT: 18.02, PAT: 17.86, ZEA: 17.80 mg g^?1). The obtained results fitted well with thermodynamic, isothermal (Langmuir) and pseudo‐second order kinetics. Low cost organo‐modified bentonite shows the promise in mitigating mycotoxin contamination, which could improve food safety and reduce environmental contamination.     

Removal of Copper,Nickel and Zinc Ions from Aqueous Solution by Chitosan‐8‐Hydroxyquinoline Beads

In this work, 8‐hydroxyquinoline is used as the active sites in cross‐linked chitosan beads with epichlorohydrin (CT‐8HQ). The CT‐8HQ material was shaped in bead form and used for heavy metal removal from aqueous solution. The study was carried out at pH 5.0 with both batch and column methods and the maximum adsorption capacity of metal ions by the CT‐8HQ was attained in 4 h in the batch experiment. The adsorption capacity order was: Cu²⁺ > Ni²⁺ > Zn²⁺ for both mono‐ and multi‐component systems with batch conditions. From breakthrough curves with column conditions, the adsorption capacity followed the order Cu²⁺ > Zn²⁺ > Ni²⁺ for both mono‐ and multi‐component systems. The CT‐8HQ beads maintained good metal adsorption capacity for all five cycles with absorbent restoration achieved with the use of 1.0 mol L^–1 HCl solution, with 90% regeneration.     

Sulfur and Carbon Co‐doped TiO2 Composite Fabricated by Lignosulphonate and Its Suitability for Removal of Cadmium

Highly toxic divalent cadmium causes serious environmental issues. To quickly monitor and/or efficiently remove this potentially toxic metal ion as well as to explore its interfacial chemistry with metal oxides, a sulfur and carbon co‐doped titania (S/C‐TiO₂) composite is synthesized via a facile sol‐gel method with the assistance of sodium lignosulphonate (SLS). The prepared composite displays a well‐crystallized TiO₂ nanostructure comprising the anatase phase. Both S and C, which are derived from the SLS template, are found to enter the TiO₂ lattice. The S/C‐TiO₂ composite exhibits a porous structure with a wide pore size distribution. The newly synthesized composite shows adsorption capability for the potentially toxic metal Cd(II). The adsorption process requires <5 min to reach equilibrium. The measured equilibrium adsorption capacity is 19.42 mg g^?1, which is twice as high as that of bare TiO₂. The removal efficiency is as high as 97%. Moreover, the materials are suitable for contaminated solutions over a wide range of pH values and various initial cadmium concentrations. A mechanism for the enhanced adsorption behavior is also proposed.     

Rice Husk Ash as a Low Cost Adsorbent for the Removal of Methylene Blue and Congo Red in Aqueous Phases

Adsorption is of significant importance for effluent treatment, especially for the treatment of colored effluent generated from the dyeing and bleaching industries. Low cost adsorbents have gained attention over the decades as a means of achieving very high removal efficiencies to meet effluent discharge standards. The present article reports on batch investigations for color removal from aqueous solutions of Methylene Blue (MB) and Congo Red (CR) using Rice Husk Ash (RHA) as an alternative low cost adsorbent. The performance analysis was carried out as a function of various operating parameters, such as initial concentration of dye, adsorbent dose, contact time, shaker speed, interruption of shaking and ionic concentration. Performance studies revealed that a very high percentage removal of color was achievable for both dyes. The maximum percentage removal of MB was 99.939%, while 98.835% removal was observed for CR. These percentage removals were better than existing systems. Detailed data analysis indicated that adsorption of MB followed the Temkin isotherm, while CR followed the Freundlich isotherm. These isotherms were feasible within the framework of experimentation. Batch kinetic data, on the other hand, indicated that pseudo second order kinetics governed adsorption in both cases. Sensitivity analysis further indicated that the effects of initial dye concentration, shaker speed, pH and ionic strength had no noticeable effect on the percentage dye removal at equilibrium. Batch desorption studies revealed that 50% acetone solution was optimum for CR, while desorption of MB varied directly with acetone concentration.     

Base Treated Cogon Grass (Imperata cylindrica) as an Adsorbent for the Removal of Ni(II): Kinetic,Isothermal and Fixed‐bed Column Studies

The adsorption of Ni(II) from aqueous solutions using base treated cogon grass or Imperata cylindrica (NHIC) was performed under batch and column modes. Batch experiments were conducted to determine the factors affecting adsorption such as pH, adsorbent dosage, initial nickel concentration, contact time and temperature. The fixed‐bed column experiment was performed to determine the practical applicability of NHIC and to obtain the breakthrough curve. Adsorption was fast as equilibrium was achieved within 60 min, and was best described by the pseudo second order model. According to the Langmuir model, a maximum adsorption capacity of 6.96 mg/g was observed at pH 5 and at a temperature of 313 K. Thermodynamic parameters such as ΔG⁰, ΔH⁰ and ΔS⁰ were calculated, and indicated that adsorption was a spontaneous and endothermic process. The mechanistic pathway of Ni(II) uptake was examined by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX) spectroscopy. The Thomas and Yoon‐Nelson models were used to analyze the fixed‐bed column data.     

Thresholds and relations for soil‐hydraulic and soil‐physical properties as a function of burn severity 4 years after the 2011 Las Conchas Fire,New Mexico,USA

Wildfire effects on soil‐physical and ‐hydraulic properties as a function of burn severity are poorly characterized, especially several years after wildfire. A stratified random sampling approach was used in 2015 to sample seven sites representing a spectrum of remotely sensed burn severity in the area impacted by the 2011 Las Conchas Fire in New Mexico, USA. Replicate samples from each site were analysed in the laboratory. Linear and linear indicator regression were used to assess thresholds in soil‐physical and ‐hydraulic properties and functional relations with remotely sensed burn severity. Significant thresholds were present for initial soil‐water content (θ_i) at 0–6 cm depth between the change in the Normalized Burn Ratio (dNBR) equal to 618–802, for bulk density (ρ_b) at 3–6 cm between dNBR equal to 416–533, for gravel fraction at 0–1 cm between dNBR equal to 416–533, for fines (the silt + clay fraction) at 0–1 cm for dNBR equal to 416–533, and for fines at 3–6 cm for dNBR equal to 293–416. Significant linear relations with dNBR were present between ρ_b at 0–1 cm, loss on ignition (LOI) at 0–1 cm, gravel fraction at 0–1 cm, and the large organic fraction at 1–3 cm. No thresholds or effects on soil‐hydraulic properties of field‐saturated hydraulic conductivity or sorptivity were observed. These results suggest that ρ_b and LOI at 0–1 cm have residual direct impacts from the wildfire heat impulse. The θ_i threshold is most likely from delayed groundcover/vegetation recovery that increases evaporation at the highest burn severity sites. Gravel and silt + clay thresholds at 0–1 cm at the transition to high burn severity suggest surface gravel lag development from hydraulic erosion. Thresholds in ρ_b from 3 to 6 cm and in silt + clay fraction from 3 to 6 cm appear to be the result of soil variability between sites rather than wildfire impacts. This work suggests that gravel‐rich soils may have increased resilience to sustained surface runoff generation and erosion following wildfire, with implications for assessments of postwildfire hydrologic and erosion recovery potential.     

Synthesis and Characterization of Poly(2‐hydroxyethylmethacrylate‐hydroxyapatite) a Novel Composite for the Removal of Lead(II) from Aqueous Solutions

In the present study, a novel adsorbent, poly (2‐hydroxyethylmethacrylate‐hydroxyapatite) [P(HEMA‐Hap)], was prepared and characterized. The synthesis was achieved by means of free‐radical polymerization and a number of structural characterization methods, including FT‐IR, XRD, TGA, SEM, BET‐porosity, and swelling tests. Pb²⁺ adsorption was performed using a series of pH, time, and temperature ranges. The reusability of the composite was also tested. The results obtained indicated that the novel adsorbent is able to bind Pb²⁺ ions with strong chemical affinity. The adsorption results were fitted to the classic Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) sorption models. Thermodynamic parameters obtained demonstrated that the sorption process was spontaneous (ΔG < 0), endothermic (ΔH > 0), as expected. The process was also consistent with the pseudo‐second‐order model, and chemical adsorption was determined to be the rate‐controlling step. It was also shown that the composite could be used for five consecutive adsorption processes.     

Wind as a cooling agent: substrate temperatures are responsible for variable lithobiont‐induced weathering patterns on west‐ and east‐facing limestone bedrock of the Negev

Spatial variability in lithobiont‐induced weathering patterns on desert rocks is aspect‐dependent. While differences between the northern and southern aspects have been extensively studied, little is known concerning the differences between east‐facing (EF) and west‐facing (WF) aspects in deserts, including the Negev Desert. Whereas cobbles on both slopes are inhabited by endolithic lichens, epilithic lichens, which render the bedrock a smooth appearance, and free‐living cyanobacteria, which give the bedrock a rugged microrelief, predominate on WF and EF bedrock, respectively. Following previous research that regarded dew as the principal factor that determines lithobiont distribution, measurements of radiation, temperature, wind and dew were carried out during 2008–2009 in the Negev Desert. The data indicated that albeit slightly higher midday surface temperatures that characterize WF surfaces (cobbles and bedrock), nocturnal temperatures on these surfaces were significantly lower, therefore facilitating higher dew condensation. High amounts of dew result from the relatively rapid drop in temperatures (14:00–20:00) due to the afternoon northwesterly sea‐breeze wind (with a cooling rate of the WF bedrock being 52.9% higher than on EF bedrock, 2.6 °C h^?1 in comparison to only 1.7 °C h^?1), and facilitate the growth of high‐chlorophyll dew‐fed (and rain‐fed) epilithic lichens, which may act as bio‐protectors on WF bedrock. Lack of condensation on EF bedrock results in turn in the growth of rain‐fed free‐living cyanobacteria, responsible for high rock dissolution and subsequently for a rugged microrelief. By affecting the nocturnal bedrock temperatures, wind acts as a cooling agent, impacting in turn the amount of dew, and subsequently lithobiont composition and weathering patterns in the Negev Desert. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.     

Schmidt‐hammer exposure‐age dating (SHD) of snow‐avalanche impact ramparts in southern Norway: approaches,results and implications for landform age,dynamics and development

Schmidt‐hammer exposure‐age dating (SHD) was applied to the problem of dating the diachronous surfaces of five distal river‐bank boulder ramparts deposited by snow avalanches plunging into the Jostedøla and Sprongdøla rivers in the Jostedalsbreen region of southern Norway. Approaches to local high‐precision linear age calibration, which controlled in different ways for boulder roundness, were developed. The mean age (SHD_mean) and the maximum age (SHD_max) of surface boulders were estimated for whole ramparts, crests and distal fringes. Interpretation was further assisted by reference to R‐value distributions. SHD_mean ages (with 95% confidence intervals) ranged from 520 ± 270 years to 5375 ± 965 years, whereas SHD_max ages (expected to be exceeded by <5% of surface boulders) ranged from 675 to 9065 years. SHD ages from the Jostedøla ramparts tended to be older than those associated with the Sprongdøla, rampart crests were younger than the respective distal fringes, and use of relatively rounded boulders yielded more consistent SHD ages than angular boulders. The SHD_mean ages indicate differences in recent levels of snow‐avalanche activity between ramparts and provide insights into rampart dynamics as boulders are deposited on rampart crests and, in smaller numbers, on the distal fringes. SHD_max ages provide minimum age estimates of rampart age (i.e. the time elapsed since the ramparts began to form) and suggest that at least some of the ramparts have been developing since the early Holocene. Copyright © 2015 John Wiley & Sons, Ltd.     

Advancing process‐based watershed hydrological research using near‐surface geophysics: a vision for,and review of,electrical and magnetic geophysical methods

We want to develop a dialogue between geophysicists and hydrologists interested in synergistically advancing process based watershed research. We identify recent advances in geophysical instrumentation, and provide a vision for the use of electrical and magnetic geophysical instrumentation in watershed scale hydrology. The focus of the paper is to identify instrumentation that could significantly advance this vision for geophysics and hydrology during the next 3–5 years. We acknowledge that this is one of a number of possible ways forward and seek only to offer a relatively narrow and achievable vision. The vision focuses on the measurement of geological structure and identification of flow paths using electrical and magnetic methods. The paper identifies instruments, provides examples of their use, and describes how synergy between measurement and modelling could be achieved. Of specific interest are the airborne systems that can cover large areas and are appropriate for watershed studies. Although airborne geophysics has been around for some time, only in the last few years have systems designed exclusively for hydrological applications begun to emerge. These systems, such as airborne electromagnetic (EM) and transient electromagnetic (TEM), could revolutionize hydrogeological interpretations. Our vision centers on developing nested and cross scale electrical and magnetic measurements that can be used to construct a three‐dimensional (3D) electrical or magnetic model of the subsurface in watersheds. The methodological framework assumes a ‘top down’ approach using airborne methods to identify the large scale, dominant architecture of the subsurface. We recognize that the integration of geophysical measurement methods, and data, into watershed process characterization and modelling can only be achieved through dialogue. Especially, through the development of partnerships between geophysicists and hydrologists, partnerships that explore how the application of geophysics can answer critical hydrological science questions, and conversely provide an understanding of the limitations of geophysical measurements and interpretation. Copyright © 2008 John Wiley & Sons, Ltd.     

Metamorphic and cooling history of the Shimanto accretionary complex,Kyushu, Southwest Japan: Implications for the timing of out‐of‐sequence thrusting

Illite crystallinity, K–Ar dating of illite, and fission‐track dating of zircon are analyzed in the hanging wall (Sampodake unit) and footwall (Mikado unit) of a seismogenic out‐of‐sequence thrust (Nobeoka thrust) within the Shimanto accretionary complex of central Kyushu, southwest Japan. The obtained metamorphic temperatures, and timing of metamorphism and cooling, reveal the tectono‐metamorphic evolution of the complex, and related development of the Nobeoka thrust. Illite crystallinity data indicate that the Late Cretaceous Sampodake unit was metamorphosed at temperatures of around 300 to 310°C, while the Middle Eocene Mikado unit was metamorphosed at 260 to 300°C. Illite K–Ar ages and zircon fission‐track ages constrain the timing of metamorphism of the Sampodake unit to the early Middle Eocene (46 to 50 Ma, mean = 48 Ma). Metamorphism of the Mikado unit occurred no earlier than 40 Ma, which is the youngest depositional age of the unit. The Nobeoka thrust is inferred to have been active during about 40 to 48 Ma, as the Sampodake unit started its post metamorphic cooling after 48 Ma and was thrust over the Mikado unit at about 40 Ma along the Nobeoka thrust. These results indicate that the Nobeoka thrust was active for more than 10 million years.     

The significance of rock structure,lithology and pre‐glacial deep weathering for the shape of intermediate‐scale glacial erosional landforms

The main landforms within the glacially scoured Precambrian rocks of the Swedish west coast are closely connected to the principal structural pattern and have lately been explained as mainly a result of etch processes, probably during the Mesozoic and with a possible second period of etching during the Neogene. To explore the effect of multiple glacial erosion on the rock surfaces, an island with two different lithologies and with striae from different directions was selected for a detailed study, focusing on the shape of roches moutonnées. Air‐photo interpretation of bedrock lineaments and roches moutonnées combined with detailed field mapping and striae measurements are used to interpret the structural and lithological control on the resulting shape. The study reveals a significant difference in shape between roches moutonnées in augen‐granite and orthogneiss. Low elongated and streamlined roches moutonnées occur in the gneiss area, striated by a Late Weichselian ice flow from the NE. This ice flow is subparallel with both the local dominant trend of topographically well‐expressed joints and the schistosity of the gneiss. Frequently, there are no signs of quarrying on the lee‐sides of the gneiss roches moutonnées and hence they resemble the shape of whalebacks, or ruwares, as typically associated with the exposed basal weathering surface found in tropical areas. The granite roches moutonnées were formed by an older ice flow from the ESE, which closely followed the etched WNW–ESE joint system of the granite. Late Weichselian ice flow from the NE caused only minor changes of the landforms. On the contrary, marks of the early ESE ice flow are poorly preserved in the gneiss area, where it probably never had any large effect as the flow was perpendicular to both schistosity and structures and, accordingly, also to the pre‐glacial relief. The study demonstrates that coincidence between ice flow direction and pre‐glacially etched structures is most likely to determine the effects of glacial erosion. Copyright © 2002 John Wiley & Sons, Ltd.     

Rock warming and drying under simulated intertidal conditions,part II: weathering and biological influences on evaporative cooling and near‐surface micro‐climatic conditions as an example of biogeomorphic ecosystem engineering

The way in which rocks and engineering materials heat‐up and dry‐out in the intertidal zone is of relevance to both weathering and ecology. These behaviours can be measured in the laboratory under controlled conditions designed to replicate those occurring in the field. Previous studies have demonstrated differences in thermal behaviours between rock types and through time as a result of soiling in terrestrial environments, but the influence of weathering and colonization on rock behaviours in the intertidal zone has not been previously assessed. We measured the warming and drying of blocks of rock (limestone and granite) and marine concrete during ‘low‐tide’ events simulated in the laboratory, before and after a period of exposure (eight months) on rock platforms in Cornwall, UK. As well as differences between the material types, temperatures of control (unexposed) and field‐exposed blocks differed in the order of 1 to 2 °C. Drying behaviours were also different after field exposure. Differences during the first few hours of exposure to air and heat were attributed to discolouration and albedo effects. Over longer periods of time, changes in the availability of near‐surface pore water as a result of micro‐scale bioerosion of limestone and the development of bio‐chemical crusts on marine concrete [observed using scanning electron microscopy (SEM)] are suggested as mechanisms enhancing and reducing, respectively, the efficiency of evaporative cooling. The retention of moisture by epilithic biofilms may also influence thermal and drying behaviours of granite. These observations represent one of the first examples of cross‐scalar biogeomorphic linkages in the intertidal zone. The significance of the results for the subsequent efficiency of weathering, and near‐surface micro‐climatic conditions experienced by colonizing organisms is discussed. The involvement of microorganisms in the creation of more (or less) ecologically stressful conditions through the alteration of substratum geomorphic properties and behaviours is suggested as an example of ‘biogeomorphic ecosystem engineering’. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluation of a simple,inexpensive, in situ sampler for measuring time‐weighted average concentrations of suspended sediment in rivers and streams

The accurate measurement of suspended sediment (<200 μm) in aquatic environments is essential to understand and effectively manage changes to sediment, nutrient, and contaminant concentrations on both temporal and spatial scales. Commonly used sampling techniques for suspended sediment either lack the ability to accurately measure sediment concentration (e.g., passive sediment samplers) or are too expensive to deploy in sufficient number to provide landscape‐scale information (e.g., automated discrete samplers). Here, we evaluate a time‐integrated suspended sediment sampling technique, the pumped active suspended sediment (PASS) sampler, which collects a sample that can be used for the accurate measurement of time‐weighted average (TWA) suspended sediment concentration and sediment particle size distribution. The sampler was evaluated against an established passive time‐integrated suspended sediment sampling technique (i.e., Phillips sampler) and the standard discrete sampling method (i.e., manual discrete sampling). The PASS sampler collected a sample representative of TWA suspended sediment concentration and particle size distribution of a control sediment under laboratory conditions. Field application of the PASS sampler showed that it collected a representative TWA suspended sediment concentration and particle size distribution during high flow events in an urban stream. The particle size distribution of sediment collected by the PASS and Phillips samplers were comparable and the TWA suspended sediment concentration of the samples collected using the PASS and discrete sampling techniques agreed well, differing by only 4% and 6% for two different high flow events. We should note that the current configuration of the PASS sampler does not provide a flow‐weighted measurement and, therefore, is not suitable for the determination of sediment loads. The PASS sampler is a simple, inexpensive, and robust in situ sampling technique for the accurate measurement of TWA suspended sediment concentration and particle size distribution.     

Comparison of LiDAR waveform processing methods for very shallow water bathymetry using Raman,near‐infrared and green signals

Airborne light detection and ranging (LiDAR) bathymetry appears to be a useful technology for bed topography mapping of non‐navigable areas, offering high data density and a high acquisition rate. However, few studies have focused on continental waters, in particular, on very shallow waters (<2 m) where it is difficult to extract the surface and bottom positions that are typically mixed in the green LiDAR signal. This paper proposes two new processing methods for depth extraction based on the use of different LiDAR signals [green, near‐infrared (NIR), Raman] of the SHOALS‐1000T sensor. They have been tested on a very shallow coastal area (Golfe du Morbihan, France) as an analogy to very shallow rivers. The first method is based on a combination of mathematical and heuristic methods using the green and the NIR LiDAR signals to cross validate the information delivered by each signal. The second method extracts water depths from the Raman signal using statistical methods such as principal components analysis (PCA) and classification and regression tree (CART) analysis. The obtained results are then compared to the reference depths, and the performances of the different methods, as well as their advantages/disadvantages are evaluated. The green/NIR method supplies 42% more points compared to the operator process, with an equivalent mean error (?4·2 cm verusu ?4·5 cm) and a smaller standard deviation (25·3 cm verusu 33·5 cm). The Raman processing method provides very scattered results (standard deviation of 40·3 cm) with the lowest mean error (?3·1 cm) and 40% more points. The minimum detectable depth is also improved by the two presented methods, being around 1 m for the green/NIR approach and 0·5 m for the statistical approach, compared to 1·5 m for the data processed by the operator. Despite its ability to measure other parameters like water temperature, the Raman method needed a large amount of reference data to provide reliable depth measurements, as opposed to the green/NIR method. Copyright © 2010 John Wiley & Sons, Ltd.     

Piecewise prediction model for watershed‐scale erosion and sediment yield of individual rainfall events on the Loess Plateau,China

Establishing a universal watershed‐scale erosion and sediment yield prediction model represents a frontier field in erosion and soil/water conservation. The research presented here was conducted on the Chabagou watershed, which is located in the first sub‐region of the hill‐gully area of the Loess Plateau, China. A back‐propagation artificial neural model for watershed‐scale erosion and sediment yield was established, with the accuracy of the model, then compared with that of multiple linear regression. The sensitivity degree of various factors to erosion and sediment yield was quantitatively analysed using the default factor test. On the basis of the sensitive factors and the fractal information dimension, the piecewise prediction model for erosion and sediment yield of individual rainfall events was established and further verified. The results revealed the back‐propagation artificial neural network model to perform better than the multiple linear regression model in terms of predicting the erosion modulus, with the former able to effectively characterize dynamic changes in sediment yield under comprehensive factor conditions. The sensitivity of runoff erosion power and runoff depth to the erosion and sediment yield associated with individual rainfall events was found to be related to the complexity of surface topography. The characteristics of such a hydrological response are thus closely related to topography. When the fractal information dimension is greater than the topographic threshold, the accuracy of prediction using runoff erosion power is higher than that of using runoff depth. In contrast, when the fractal information dimension is smaller than the topographic threshold, the accuracy of prediction using runoff depth is higher than that of using runoff erosion power. The developed piecewise prediction model for watershed‐scale erosion and sediment yield of individual rainfall events, which introduces runoff erosion power and runoff depth using the fractal information dimension as a boundary, can be considered feasible and reliable and has a high prediction accuracy. Copyright © 2013 John Wiley & Sons, Ltd.