Photosynthetic bark: Use of chlorophyll absorption continuum index to estimate Boswellia papyrifera bark chlorophyll content

Quantification of chlorophyll content provides useful insight into the physiological performance of plants. Several leaf chlorophyll estimation techniques, using hyperspectral instruments, are available. However, to our knowledge, a non-destructive bark chlorophyll estimation technique is not available. We set out to assess Boswellia papyrifera tree bark chlorophyll content and to provide an appropriate bark chlorophyll estimation technique using hyperspectral remote sensing techniques. In contrast to the leaves, the bark of B. papyrifera has several outer layers masking the inner photosynthetic bark layer. Thus, our interest includes understanding how much light energy is transmitted to the photosynthetic inner bark and to what extent the inner photosynthetic bark chlorophyll activity could be remotely sensed during both the wet and the dry season. In this study, chlorophyll estimation using the chlorophyll absorption continuum index (CACI) yielded a higher R² (0.87) than others indices and methods, such as the use of single band, simple ratios, normalized differences, and conventional red edge position (REP) based estimation techniques. The chlorophyll absorption continuum index approach considers the increase or widening in area of the chlorophyll absorption region, attributed to high concentrations of chlorophyll causing spectral shifts in both the yellow and the red edge. During the wet season B. papyrifera trees contain more bark layers than during the dry season. Having less bark layers during the dry season (leaf off condition) is an advantage for the plants as then their inner photosynthetic bark is more exposed to light, enabling them to trap light energy. It is concluded that B. papyrifera bark chlorophyll content can be reliably estimated using the chlorophyll absorption continuum index analysis. Further research on the use of bark signatures is recommended, in order to discriminate the deciduous B. papyrifera from other species during the dry season.     

Relevant Reducing Agents in Remediation Fe0/H2O Systems

Metallic iron (Fe⁰) is often reported as a reducing agent for environmental remediation. There is still controversy as to whether Fe⁰ plays any significant direct role in the process of contaminant reductive transformation. The view that Fe⁰ is mostly a generator of reducing agents (e.g. H, H₂ and Fe^II) and Fe oxyhydroxides has been either severely refuted or just tolerated. The tolerance is based on the simplification that, without Fe⁰, no secondary reducing agents could be available. Accordingly, Fe⁰ serves as the original source of electron donors (including H, H₂ and Fe^II). The objective of this communication is to refute the named simplification and establish that quantitative reduction results from secondary reducing agents. For this purpose, reports on aqueous contaminant removal by Al⁰, Fe⁰ and Zn⁰ are comparatively discussed. Results indicated that reduction may be quantitative in aqueous systems containing Fe⁰ and Zn⁰ while no significant reduction is observed in Al⁰/H₂O systems. Given that Al⁰ is a stronger reducing agent than Fe⁰ and Zn⁰, it is concluded that contaminant reduction in Fe⁰/H₂O systems results from synergic interactions between H/H₂ and Fe^II within porous Fe oxyhydroxides. This conclusion corroborates the operating mode of Fe⁰ bimetallics as H/H₂ producing systems for indirect contaminant reduction.     

Thorium(IV) removal from aqueous medium by citric acid treated mangrove endophytic fungus Fusarium sp. #ZZF51

Thorium(IV) biosorption is investigated by citric acid treated mangrove endophytic fungus Fussarium sp. #ZZF51 (CA-ZZF51) from South China Sea. The biosorption process was optimized at pH 4.5, equilibrium time 90 min, initial thorium(IV) concentration 50 mg L⁻¹ and adsorbent dose 0.6 g L⁻¹ with 90.87% of removal efficiency and 75.47 mg g⁻¹ of adsorption capacity, which is obviously greater than that (11.35 mg g⁻¹) of the untreated fungus Fussarium sp. #ZZF51 for thorium(IV) biosorption under the condition of optimization. The experimental data are analyzed by using isotherm and kinetic models. Kinetic data follow the pseudo-second-order model and equilibrium data agree very well with the Langmuir model. In addition, FTIR analysis indicates that hydroxyl, amino, and carbonyl groups act as the important roles in the adsorption process.     

Nitrate removal and young stream water fractions at the catchment scale

Despite extensive research on nitrate export and removal, nutrient contamination remains a major threat to water bodies worldwide. At the local scale, nitrate removal is governed by biogeochemical conditions that vary in space and time, making integration to entire landscapes critical. Water transit times have often been used to describe solute transport, but the relation between water age and nitrate removal at the catchment scale is still poorly understood. We test the hypothesis that nitrate removal peaks when the fraction of young water in discharge is at its minimum, because nitrate removal occurs mostly under dry conditions where deeper, older groundwater dominates streamflow. We tested this hypothesis by exploring a detailed water quality record from the Kervidy–Naizin catchment (FR) and comparing the dynamics of nitrate to those of a conservative solute (chloride). We find that estimates of nitrate removal are consistent with previous estimates at the site and they show a good (inverse) correlation with the fraction of streamflow that is younger than 2.5 months. However, this young water fraction cannot be used to predict nitrate removal in the winter–spring period, when no removal is observed regardless of streamflow age. While this leads us to reject our hypothesis during the winter period, it also suggests that water age distributions and their correlation with nitrate removal can possibly reveal distinct sources of stream water at different hydrologic regimes and relevant biogeochemical reactions.     

Sediment removal efficiency of siphon dredging with wedge-type suction head and float tank

Siphon dredging with a float tank and different siphon suction heads, including the plain-type and wedge-type with/without side holes, through flume experiments were used to investigate the reservoir sediment removal efficiency. The experiment revealed maximum suction pressure and velocity when the distance from the suction head to the bed was about 25% of suction head diameter. Suction pressure decreased rapidly as the distance from the suction head to the bed increased to 50% and 100% of suction head diameter. Suction pressure achieved by wedge-type suction head was only 16.9-17.6% of that around plain-type suction head, and the velocity around wedge-type suction head was 64.7-68.4% of that around plain-type suction head. However the plain-type suction head was easily clogged doe to its long bobbing period. The average bobbing period for the plain-type suction head was about 105-263% that of the wedge-type suction head. The sediment removal efficiency was achieved when float tank diameter was 3-4 times that of the suction head. Flow discharge and sediment removal increased as the suction head diameter and side hole diameter increased, respectively. The most efficient side hole area was an area within 15% of suction head area. Totally, the optimal sediment removal efficiency was the wedge angle of 20° with 3 side holes. The efficiency of sediment dredging by siphon suction with a suction tube passing through the dam bottom was better than that with suction passing over the top of the dam. The wedge-type siphon suction with a float tank is preferable for sediment dredging in small reservoirs because it is inexpensive and efficient.     

基于第二代Curvelet变换的面波压制(英文)

针对面波能量强、频率低、视速度低等特点,本文提出了基于第二代Curvelet变换的多尺度、多方向分解的面波压制方法,充分利用Curvelet变换的多尺度、多方向功能,分离出含有面波的尺度和方向然后利用面波与有效波在Curvelet域基本不重叠的特性,进行信噪分离处理。这种方法在实际叠前地震数据的处理中,能够有效压制面波,同时较好地保护有效反射波,特别是反射波的低频分量。文中提出的基于第二代Curvelet变换的去面波方法是一种较好的保幅去噪方法。     

Removal of the Alphazurine FG Dye from Simulated Solution by Electrocoagulation

The removal of Alphazurine FG (AF) dye from water by an electrocoagulation process has been studied. The effect of some operational parameters, such as anode material, current density, initial dye concentration, pH of solution, conductivity, and inter‐electrode distance, on the removal efficiency was investigated. Iron and aluminum were used as anodes in the electrocoagulation cell. It was found that the efficiency of the iron anode was better than that of the aluminum anode for AF removal. The factors that affected the removal efficiency were the current density and the initial dye concentration. The removal efficiency increased from about 35% at 25 A m^–2 to about 97% at 100 A m^–2, during 4 min of electrocoagulation. The results exhibited pseudo‐first‐order kinetics for AF removal by electrocoagulation. In addition, a mathematical model was successfully established for predicting the removal efficiency. A comparison between the model results and experimental data gave a high correlation coefficient (R² = 0.9925), which indicates that the model is able to predict the removal efficiency of AF.     

Shaking table test and numerical simulation of an RC frame‐core tube structure for earthquake‐induced collapse

The reinforced concrete frame‐core tube structure is a common form of high‐rise building; however, certain vertical components of these structures are prone to be damaged by earthquakes, debris flow, or other accidents, leaving no time for repair or retrofit. This study is motivated by a practical problem—that is, the seismic vulnerability and collapse resistant capability under future earthquakes when a vertical member has failed. A reduced scale model (1:15 scale) of a typical reinforced concrete frame‐core tube with a corner column removed from the first floor is designed, fabricated, and tested. The corner column is replaced by a jack, and the failure behavior is simulated by manually unloading the jack. The model is then excited by a variety of seismic ground motions on the shaking table. Experimental results concerning the seismic responses and actual process of collapse are presented herein. Finally, the earthquake‐induced collapse process is simulated numerically using the software program ANSYS/LS‐DYNA. Validation and calibration of the model are carried out by comparison with the experimental results. Furthermore, based on both experimental investigations and numerical simulations, the collapse mechanism is discussed, and some suggestions on collapse design are put forward. Copyright © 2016 John Wiley & Sons, Ltd.     

不同碳氮比对辽河口湿地总氮去除的影响

于2010年5月～10月采用现场模拟培养法探讨了辽河口芦苇湿地沉积物中的总氮去除效果,并分析了不同梯度C/N比(5∶1、10∶1、15∶1)对沉积物中总氮去除效果的影响。结果表明:在自然状态下,有植被芦苇湿地总氮去除率比无植被湿地高;当施加C/N因素后可以提高沉积物中总氮去除率,C/N比对裸滩湿地中氮的去除效果比芦苇湿地明显;在有植被芦苇湿地中C/N比为10时总氮去除率最高,而在无植被湿地中C/N比值为15时总氮去除率最高;8月份各实验组中总氮去除率最高。影响辽河口湿地沉积物脱氮效果主要环境因子还有温度、盐度、含水率和pH等。