Quantitative Morphology Of C/1995 O1 (Hale–Bopp) In February – April 1997

Extensive widefield CCD direct imaging of C/1995 O1 (Hale-Bopp) at UBVRI was carried out at Hoher List Observatory with the 1.06 m telescope (field of view 20′ × 20′) and at Potsdam Observatory with the 0.70 m telescope (field of view 8′ × 8′). The corresponding spatial resolution is 850–1000 km pix^-1and 525–590 km pix^-1, respectively. The data covers 25 nights from February 20 to April 21, 1997. In order to quantify the various features in the apparent inner coma we introduce a new tomographic method that minimizes the morphological bias caused by image processing. The tomographic analysis leads to quantitative maps refering to the position and intensity of the dust ejections for each image frame. Variability and periodicity within the inner coma can be thoroughly deduced due to various sets of consecutive nights in the observation period mentioned above. The results are compared with applications of adaptive Laplace filtering. This revised version was published online in July 2006 with corrections to the Cover Date.     

Streamflow estimation using optimal regional dependency function

The determination of spatial dependency of regionalized variable (ReV) is important in engineering studies. Regional dependency function that leads to calculation of weighting coefficients is required in order to make regional or point‐wise estimations. After obtaining this dependency function, it is possible to complete missing records in the time series and locate new measurement station. Also determination of regional dependency function is also useful to understand the regional variation of ReV. Point Cumulative Semi‐Variogram (PCSV) is another methodology to understand the regional dependency of ReV related to the magnitude and the location. However, this methodology is not useful to determine the weighting coefficient, which is required to make regional and point‐wise estimations. However, in Point Semi‐Variogram (PSV) proposed here, weighting coefficient depends on both magnitude and location. Although the regional dependency function has a fluctuating structure in PSV approach, this function gradually increases with distance in PCSV. The study area is selected in Mississippi river basin with 38 streamflow stations used for PCSV application before. It is aimed to compare two different geostatistical models for the same data set. PSV method has an ability to determine the value of variable along with optimum number of neighbour stations and influence radius. PSV and slope PSV approaches are compared with the PCSV. It was shown that slope slope point semi‐variogram (SPSV) approaches had relative error below 5%, and PSV and PCSV methods revealed relative errors below 10%. Copyright © 2009 John Wiley & Sons, Ltd.     

Assessments on slope instabilities triggered by engineering excavations near a small settlement (Turkey)

In this study, the mechanisms of slope instabilities triggered by engineering excavations at location of a planned tunnel portal in the northwest region of Turkey were assessed, and stability of the current slopes which has impacts on safety of a settlement (village) and agricultural fields was investigated. In the first stage of the study, in order to identify the geological units and structural properties of the sedimentary rocks in the area, to clarify the mechanisms of instabilities and to characterize discontinuity and rock mass properties field works were conducted. In this content, geotechnical boreholes, geophysical explorations between the boreholes, line surveys to explore discontinuity properties, preparation of slope profiles using topographical techniques and sampling of rock blocks and discontinuity planes were performed. In the second stage, laboratory tests were carried out on the samples to determine the geomechnical properties of the slope forming materials and discontinuities. Then, back analyses of the instabilities were made to assess the responsible shear strength parameters of the geological units during failures by considering laboratory shear test results too. Based on the backanalyses of the failures, the strength properties of the slope debris were estimated, and it has been clarified that the residual shear strength properties are the factors controlling slip mechanism along the beddings. Following the stability analyses, it is understood that a further instability along the mass or bedding planes in the failed and redesigned area are not expected, if the current slope geometry is not changed. However, safety factor calculated for the slope in the debris is 1.1 which is well below the recommended value in the literature. The minimum safety factor for currently stable slopes which were cut at the eastern part of the failed area is 1.22 which is also less than that suggested in literature. Some remedial measures such as mini-pile or slope flattening are suggested after analyses to increase the factor of safety for this part below the settlement.     

灰色稳健总体最小二乘估计及高铁路基变形预测

最小二乘估计和部分变量误差模型的总体最小二乘估计不具备抵御粗差的能力。鉴于粗差可能同时出现在灰色白化微分方程的观测值和系数矩阵中,本文提出基于IGGⅢ抗差方案的部分变量总体最小二乘稳健估计。结合仿真数据和高铁路基观测数据,系统地比较稳健最小二乘、部分变量总体最小二乘、本文算法参数估计结果和算法稳定性。结果表明,本文算法预测精度高,可以应用到高铁路基沉降预测中。     

Properties and organic activation of ocean clay in the East Pacific

In order to make use of ocean clay reasonably and excavate its potential applications the properties of ocean clay in Chinese investigating area of the East Pacific have been tested with the chemical analysis, XRFS, ICP/MAS, granulometry and SSA, etc. The results show that the clay sediments of this area are rich in clay minerals, fine granularity, bigger SSA, bigger water absorbability and lower ion changing ability etc. To improve the adaptability of ocean clay and macromolecule materials, using the dry milling method with silane, aluminate, stearic acid coupling agents etc the properties of ocean clay are improved. The effect has been evaluated by testing the water absorbing of the modified ocean clay and their dispersing in paraffin liquid. The result is that KH550 is better than any other active reagents, and the best activation technics is that 1.5% (volume) of KH550 quantity, 20min of milling time. The DTA, XRD, SEM and IR analyses and SSA testing show that the organic activation can not change the mineral structure but can densify the structure of clay, and activation mechanism is chemical covered mainly and chemical combined secondly.     

Historical Sediment Record of ~(137)Cs, δ-HCH,and δ~(13)C Reflects the Impact of Land Use on Soil Erosion

This paper reports the concentrations of 137 Cs, hexachlorocyclohexane(HCH), dichlorodiphenyltrichloroethanes(DDT) and its main degradation products, δ13C, and organic carbon in pond sediments(0-210 cm, sectioned by 2-20 cm interval) and surface soils(the 0-3 cm horizon) collected in 2010 from Chenjia catchment, which is located in Yanting county in the hilly central Sichuan of China. α-, δ-, and γ-HCH, DDT, and DDD were not detected throughout the sediment profile. Trace concentrations of δ-HCH(0.89-29.31 ng g-1) and p,p′-DDE(1.85-6.02 ng g-1) were detected only in top 40 cm sediment. The 137 Cs fallout peak in 1963(corresponding to the 55-60 cm depth), the sedimentary signature left by the last year of HCH use in 1989(an additional indicator at 20-25 cm), and the obvious original channel bed prior to the construction of the pond in 1956 were used as temporal markers to estimate changes in average sedimentation rate between different periods due to changes in land use. Continuous, marked decrease in average sedimentation rate(i.e., 3.79, 1.35 and 1.07 cm year-1 in 1956-1963, 1963-1989, and 1989-2010, respectively)over time was observed, probably due to the reforestation, abandoning of steep sloping farmland for afforestation and natural re-vegetation(implementation of the Grain for Green Program), and the conversion of part of gently sloping farmland terraces to orchard land since the 1980 s, especially since the 1990 s. This was corroborated by the observed decrease(more negative) in δ13C of sediment towards the surface, which indicates increased relative contribution of eroded soil particles coming from slopes with increased tree cover in sediment source area. Combined use of 137 Cs, δ-HCH, and δ13C record in sediments has been demonstrated to be a powerful approach to reconstruction of response in sedimentation rate to historical land use changes.     

Erratum to: Purification and characterization of iron-cofactored superoxide dismutase from Enteromorpha linza

<正>Erratum to:Chinese Journal of Oceanology and Limnology Vol.31 No.6,P.1190-1195,2013http://dx.doi.org/10.1007/s00343-013-3049-3The supporting grant information on the footnote of the original version of this article needs to be altered and updated.The new information is given below.     

Decomposition of algal lipids in clay-enriched marine sediment under oxic and anoxic conditions

A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched marine sediment under oxic and anoxic conditions. During the 245-day incubation period, changes in the concentrations of TOC, major algal fatty acid components (14:0, 16:0, 16:1, 18:1 and 20:5), and n-alkanes (C₁₆–C₂₃) were quantified in the samples. Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic conditions. Adsorption of fatty acids onto clay minerals was a rapid and reversible process. Using a simple G model, we calculated the decomposition rate constants for TOC, n-alkanes and fatty acids which ranged from 0.017–0.024 d⁻¹, 0.049–0.103 d⁻¹ and 0.011 to 0.069 d⁻¹, respectively. Algal organic matter degraded in two stages characterized by a fast and a slow degradation processes. The addition of clay minerals montmorillonite and kaolinite to the sediments showed significant influence affecting the decomposition processes of algal TOC and fatty acids by adsorption and incorporation of the compounds with clay particles. Adsorption/association of fatty acids by clay minerals was rapid but appeared to be a slow reversible process. In addition to the sediment redox and clay influence, the structure of the compounds also played important roles in affecting their degradation dynamic in sediments.     

Influence of shallow infiltration on time-lapse ERT: Experience of advanced interpretation

Previous time-lapse Electrical Resistivity Tomography (ERT) studies have experienced difficulties in reconstructing reliable calculated resistivity changes in the subsurface. Increases or decreases of resistivity appear in the calculated ERT image where no changes were noted in the subsurface, leading to erroneous hydrological interpretations of the geophysical results. In this article, we investigate how a variation of actual resistivity with time and at shallow depth can influence time-lapse ERT results and produce resistivity artefacts at depth. We use 1 and 2-D numerical modelling to simulate infiltration scenarios. Using a standard time-lapse inversion, we demonstrate the resistivity artefact production according to the electrode spacing parameter. We used an advanced inversion methodology with a decoupling line at shallow depth to attenuate or remove resistivity artefacts. We also applied this methodology to a field data set obtained in a semi-arid environment in Burkina Faso, West Africa. Here, time-lapse ERT shows several resistivity artefacts of calculated resistivity if a standard inversion is used. We demonstrate the importance of a dense sampling of shallow resistivity variations at shallow depth. Advanced interpretation allows us to significantly attenuate or remove the resistivity artefact production at intermediate depth and produce reliable interpretation of hydrological processes.     

Digital mapping of coastal boulders – high-resolution data acquisition to infer past and recent transport dynamics

Coastal boulder fields provide clues to long-term frequency-magnitude patterns of coastal flooding events and have the potential to play an important role in coastal hazard assessment. Mapping boulders in the field is time and labour-intensive, and work on intertidal reef platforms, as in the present study, is physically challenging. By addressing coastal scientists who are not specialists in remote sensing, this contribution reports on the possibilities and limitations of digital applications in boulder mapping in Eastern Samar, Philippines, where recent supertyphoons Haiyan and Hagupit induced high waves, coastal flooding and boulder transport. It is demonstrated how satellite imagery of sub-metre resolution (from Pléiades and WorldView-3 imagery) enables efficient analysis of transport vectors and distances of larger boulders, reflecting variation in latitudes of both typhoon tracks and approaching angles of typhoon-generated waves. During the investigated events, boulders with a-axes of up to 8 m were clearly identified to have been shifted for up to 32 m, mostly along the seaward margin of the boulder field. It is, however, hard to keep track of smaller boulders, and the length of a-axes and b-axes including their orientation is often impossible to map with sufficient accuracy. Orthophotographs and digital surface models created through the application of an unmanned aerial vehicle and the ‘Structure from Motion’ technique provide ultra-high-resolution data, and have the potential to not only improve the results of satellite image analysis, but also those from field mapping and may significantly reduce overall time in the field. Orthophotographs permit unequivocal mapping of a-axes and b-axes including their orientation, while precise values for c-axes can be derived from the respective digital surface models. Volume of boulders is best inferred from boulder-specific Structure from Motion-based three-dimensional models. Battery power, flight speed and altitude determine the limits of the area covered, while patches shielded by the boulders are difficult to resolve. For some tasks, field mapping remains mandatory and cannot be replaced by currently available remote sensing tools: for example, sampling for rock type, density and age dating, recording of lithological separation of boulders from the underlying geological unit and of geomorphic features on a millimetre to decimetre-scale, or documentation of fine-grained sediment transport in between the boulders in supratidal settings. In terms of future events, the digital products presented here will provide a valuable reference to track boulder transport on a centimetre to decimetre-scale and to better understand the hydrodynamics of extreme-wave events on a fringing reef coastline.