Effects of saline water irrigation on soil properties in northwest China

Due to the lack of freshwater, highly saline groundwater was the main irrigation source in the last few decades in the Minqin Basin, which is in northwest China. The study evaluates the effects of salt accumulation on the soil physical–chemicals properties. Undisturbed and disturbed soil samples were taken from the experiment site, which was irrigated with saline water at a concentration of 0.8, 2 and 5 g L⁻¹ (coded later as C₀₈, C₂ and C₅). Undisturbed soil samples, at depths of 0–45 and 45–60 cm were taken to determine the water retention curve (WRC). Moreover, in the same place, another set of undisturbed soil samples were taken to determine the porosity and pore-size distribution (PoSD). From the WRC, the water-holding capacity of the soil was estimated. Disturbed soil samples at depths of 0–20, 0–45, 45–60 and 80–100 cm were taken to determine the index of aggregates stability in water (IC). The electrical conductivity of the saturated paste (EC_e) was determined at depths of 0–30, 30–60 and 60–90 cm, during the irrigation season on C₀₈, C₂ and C₅ treatments. The results show that the total porosity and the index of aggregates stability in water decrease with the increasing salinity of irrigation water, and the EC_e increases with the increasing salinity of irrigation water especially in the surface soil. The water-holding capacity (WHC) of soil also increases with the increasing salinity of irrigation water.     

Metabolic responses in gills of Manila clam Ruditapes philippinarum exposed to copper using NMR-based metabolomics

Copper is an important heavy metal contaminant with high ecological risk in the Bohai Sea. In this study, the metabolic responses in the bioindicator, Manila clam (Ruditapes philippinarum), to the environmentally relevant copper exposures were characterized using NMR-based metabolomics. The significant metabolic changes corresponding to copper exposures were related to osmolytes, intermediates of the Krebs cycle and amino acids, such as the increase in homarine, branched chain amino acids and decrease in succinate, alanine and dimethylamine in the copper-exposed clam gills during 96 h exposure period. Overall, Cu may lead to the disturbances in osmotic regulation and energy metabolism in clams during 96 h experimental period. These results demonstrate that NMR-based metabolomics is applicable for the discovery of metabolic biomarkers which could be used to elucidate the toxicological mechanisms of marine heavy metal contaminants.     

The Optimal Cross-section Design of the “Trapezoid-V” Shaped Drainage Canal of Viscous Debris Flow

Debris flow drainage canal is one of the most widely used engineering measures to prevent and manage debris flow hazards.The shape and the sizes of the cross-section are important parameters when design debris flow drainage canal.Therefore,how to design the appropriate shape and sizes of the cross-section so that the drainage canal can have the optimal drainage capacity is very important and few researched at home and abroad.This study was conducted to analyze the hydraulic condition of a Trapezoid-V shaped drainage canal and optimize its cross-section.By assuming characteristic sizes of the cross-section,the paper deduced the configuration parameter of the cross-section of a Trapezoid-V shaped debris flow drainage canal.By theory analysis,it indicates that the optimal configuration parameter is only related to the side slope coefficient and the bottom transverse slope coefficient.For this study,the Heishui Gully,a first-order tributary of the lower Jinsha River,was used as an example to design the optimal cross-section of the drainage canal of debris flow.     

中国分县生态承载力供需平衡空间格局分析(英文)

A balanced ecological carrying capacity and its understanding are important to achieve sustainable development for human kind.Here,the concept of ecological carrying capacity has been used for measuring the dependencies between human and nature.China’s ecological balance between supply and demand has become a global concern and is widely debated.In this study the ’Ecological Footprint’ method was used to analyze the supply-demand balance of China’s ecological carrying capacity.Firstly,the ecological supply and demand balance was calculated and evaluated,and secondly,the ecological carrying capacity index (ECCI) was derived for each county of China in 2007,and finally this paper systematically evaluated the ecological carrying capacity supply-demand balance of China.The results showed that ecological deficit appeared to be the main characteristic of ecological carrying capacity supply-demand balance in 2007 of China at county scale.In general,more than four-fifths of the Chinese population was concentrated in less than one-third of the land area and more than two-thirds of the land area was inhabited by less than one-fifth of the population.The spatial distribution of the ecological carrying capacity demand-supply was unbalanced ranging from significant overloading to affluence from southeastern to northwestern part of China.It appeared to be more dominant in regions located at coastal areas which are attracted by migrants and had a generally higher population density.Along with the rapid development and urbanization trends in China,ecological deficits in these regions will become more severe.     

Hollow Cylinder Simulation Experiments of Galleries in Boom Clay Formation

In the context of nuclear waste disposal in clay formations, laboratory experiments were performed to study at reduced scale the excavation damaged zone (EDZ) induced by the construction of galleries in the Boom clay formation. For this purpose, thick-walled hollow cylindrical samples were subjected (after recovery of in situ stress conditions) to a decrease in the inner confining pressure aiming at mimicking a gallery excavation. X-ray computed tomography (XRCT) scans of the specimens were carried out through the testing cell before and after the mechanical unloading and allowed to quantify the displacements undergone by the clay as a result of the mechanical unloading. The deformation of the hollow cylinders and the inferred extent of the damaged zone around the central hole are found to depend on the orientation of the specimen with respect to the bedding planes and show a great similarity with in situ observations around galleries and boreholes at Mol URL in the Boom clay formation. In the experiments performed on samples cored parallel to the bedding, the damaged zone is not symmetrical with respect to the hole axis and extends more in the direction parallel to the bedding. It is the same for the radial convergence of the hole walls which is larger in the direction parallel to bedding than in the perpendicular one. In contrast, a test on a sample cored perpendicularly to the bedding did not show any ovalisation of the central hole after the mechanical unloading. These observations confirm the significance of the pre-existing planes of weakness (bedding planes) in Boom clay and the need for a correct consideration of the related mechanical anisotropy.     

基于贝叶斯模型平均的全球洪水中长期预报评估研究

筛选全球5839个水文站逐日径流数据,采用超阈值采样法提取洪水发生频率及时间,将各季节最大日流量作为季节洪水量级,以优选的多个大尺度气候因子的最佳前置月份序列作为潜在预报因子,基于贝叶斯模型平均法构建全球尺度洪水中长期预报模型,并利用均方误差技术指数（MSESS）评价模型的预报效果。结果表明：全球范围内,洪水量级和频率模拟预报效果合格（0.6>MSESS>0.2）的水文站点占比分别为48%和28%;利用前置季节气候因子数据,驱动所构建的洪水中长期预报模型,有效预报了2020年鄱阳湖流域洪水量级将异常偏高。     

合成孔径雷达干涉测量原理与应用

合成孔径雷达（SAR）是一种微波相干成像方法，应用不同波段的雷达信号可以对地球表面不同的散射特性成像。合成孔径雷达干涉（InSAR）是将两个不同轨道位置或不同时间获得的复数SAR数据进行相位差分处理，从这些差分干涉数据中可以提取特别有用的信息，用于绘制地形图，测量诸如地震、火山、冰川运动等造成的地形变，研究植被覆盖特性、洋流等。介绍了InSAR的基本原理与应用，并对影响干涉结果的一些重要因素进行了分析。     

大气折射对InSAR影响的定量分析

星载SAR重复轨道干涉利用不同时间观测的SAR影像数据形成干涉图，干涉相位中包含有成像几何、大气、地形以及地面形变等信息。为此，分析了干涉图中大气参数(气压、温度与相对湿度)对干涉相位的影响，计算了参数变化对干涉相位、高程与形变误差的影响量，并以图形方式描述了分析结果。     

Simulating Astrophysical Jets in Laboratory Experiments

Pulsed-power technology and appropriate boundary conditions have been used to create simulations of magnetically driven astrophysical jets in a laboratory experiment. The experiments are quite reproducible and involve a distinct sequence. Eight initial flux tubes, corresponding to eight gas injection locations, merge to form the jet, which lengthens, collimates, and eventually kinks. A model developed to explain the collimation process predicts that collimation is intimately related to convection and pile-up of frozen-in toroidal flux convected with the jet. The pile-up occurs when there is an axial non-uniformity in the jet velocity so that in the frame of the jet there appears to be a converging flow of plasma carrying frozen-in toroidal magnetic flux. The pile-up of convected flux at this “stagnation region” amplifies the toroidal magnetic field and increases the pinch force, thereby collimating the jet.