Soil macroporosity and infiltration characteristics of a forest podzol

Spatial distribution of soil macroporosity was determined for a forest podzol from tension infiltrometer measurements at the soil surface. Surface‐derived macroporosity values were compared with point infiltration characteristics obtained from soil water content and soil water chemistry measurements during an experimental irrigation, and with parameters of a kinematic wave model applied to soil water content data. Macroporosity estimated by the tension infiltrometer ranged from 0·00087 to 0·0219% of soil volume, and infiltration at these two sites was dominated by propagation of a well‐defined wetting front through the soil profile and bypass flow via soil macropores, respectively. Infiltration at sites with intermediate macroporosities reflected a combination of these two processes, although results were inconclusive at one site owing to lateral flow at the base of the soil profile. There was no agreement between macroporosities estimated by the tension infiltrometer and the kinematic wave model. The maximum soil conductance parameter within the profile at a site, however, was related directly to the surface‐derived macroporosity. The partial agreement between surface‐derived macroporosity estimates and point infiltration characteristics shown here supports the use of tension infiltrometry as a rapid, non‐destructive method of assessing spatial variations in the relative contribution of macropore flow to the infiltration process. Copyright © 2000 John Wiley & Sons, Ltd.     

滇中地区产汇流分析探讨

依据云南省滇中地区16个水文站共31年(1980~2010年)实测水文资料,应用二水源新安江模型进行降雨径流分析,用推理过程线法进行汇流分析,研究滇中地区产汇流参数地理变化规律,为无水文资料的中小河流开展水文计算和站网规划提供参考。研究结果表明:分析得出的参数具有一定的代表性,分析成果取得较好的效果。     

Differences in gravity‐dominated unsaturated flow during autumn rains and snowmelt

Five tracer experiments have been performed in a coarse‐textured soil near the new main airport at Gardermoen, Norway. In two lysimeter walls, 30 and 40 measuring points form the basis for spatial moment calculations. Although experiments were performed under different meteorological conditions (autumn and snowmelt) and at two different sites, the ratios of centres of vertical mass over cumulative infiltration were of the same order of magnitude, indicating a gravity‐dominated flow. Two‐dimensional transport simulations with SUTRA (Voss, 1984), with a priori estimated input parameters and random fields of soil hydraulic properties revealed a relatively good agreement with the experimental results. Three possible sources of heterogeneity affecting the vertical displacement of solute during snowmelt were identified: variability of soil physical properties, soil surface elevations and variability of ground frost during the melting period. To obtain accurate predictions, soil heterogeneity was the most important factor to characterize for the coarse‐textured soil under consideration. Copyright © 1999 John Wiley & Sons, Ltd.     

降水入渗补给过程中优先流的确定

优先流是降水、灌溉水等入渗补给地下水的主要形式之一, 流速快, 流动路径复杂, 难以定量描述.针对优先流难以定量描述的问题, 以郑州地中渗透仪观测资料为基础, 探讨了新乡亚砂土等试筒降水入渗过程及其中的优先流补给量比例.根据土壤的水力性质、气候等资料建立不存在优先流的数值模拟模型来刻画降水入渗补给过程, 通过模拟获得的地下水入渗补给量与实测地下水入渗补给量的历时曲线, 将大于模拟值的实测值视为优先流的量及确定其在总补给量中所占的比例.结果表明, 优先流占总补给量的比例在10%~80%之间; 随着土壤粘性增加, 优先流所占比例呈增加趋势; 随地下水位埋深的增大, 优先流所占比例呈逐渐下降趋势.      

Preparation of Biomorphic SiC/C Ceramics from Pine Wood via Supercritical Ethanol Infiltration

Biomorphic （wood derived） carbide ceramics with an overall composition in the SiC/C was produced by supereritical ethanol infiltration of low viscosity tetraethylorthosilicate/supercritical ethanol into biologically derived carbon templates （CB-templates） and in situ hydrolysis into Si（OH）4-gel, the Si（OH）4-gel was calcined at 1400℃ to promote the polycondensation of Si（OH）4-gel into SiO2-phase and then carbonthermal reduction of the SiO2 with the biocarbon template into highly porous, biomorphic SiC/C ceramics. The phases and morphology conversion mechanism of resulting porous SiC/C ceramics have been investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and Fourier transform infrared spectroscopy （FT-IR）. Experimental results showed that the biomorphic cellular morphology of pinewood charcoal was remained in the porous SiC/C ceramic with high precision that consisted of β-SiC with minority of α-SiC and the remain free carbon existed in amorphous phase.     

基于网络药理学和免疫浸润探讨荜茇抗血吸虫病相关肝细胞癌的作用机制

目的：通过网络药理学和免疫浸润探讨中药荜茇抗血吸虫病相关肝细胞癌的作用机制。方法：通过TCMSP、TCMIP数据库查找荜茇主要化学成分及其作用靶点;通过GeneCards、OMIM、TTD数据库收集血吸虫病及肝细胞癌相关靶点,构建“药物-成分-靶点”和“成分-靶点-通路”网络图,对药物和疾病的交集靶点进行蛋白质-蛋白质相互作用（PPI）分析;通过R语言对交集靶点进行基因本体（GO）功能和京都基因与基因组百科全书（KEGG）通路富集分析;通过GEPIA和UALCAN数据库对潜在靶点进行表达差异及生存预后分析;通过TIMER数据库对核心靶点进行免疫浸润分析。结果：获得荜茇抗血吸虫病及肝细胞癌潜在靶点11个,其中肿瘤坏死因子（TNF）、白细胞介素-1β（IL-1β）、白细胞介素-6（IL-6）、白细胞介素-10（IL-10）、环加氧酶2（PTGS2）等可能是荜茇发挥作用的潜在靶点;KEGG通路富集主要涉及肿瘤坏死因子（TNF）信号通路、C型凝集素受体信号通路等,生物信息学结果表明葡萄糖-6-磷酸脱氢酶（G6PD）可能在荜茇治疗血吸虫病相关肝细胞癌过程中发挥重要作用。结论：本研究初步预测了荜茇抗血吸虫病相关肝细胞癌的分子机制,为进一步深入研究及临床应用提供了理论依据。     

WATER MOVEMENT AND VEGETATION PATTERNS ON SHRUBLAND AND AN ABANDONED FIELD IN TWO DESERTIFICATION-THREATENED AREAS IN SPAIN

Four large-scale rainfall simulation experiments were conducted in Spain to improve the understanding of the relationship between soil water dynamics, soil erosion and land degradation. On different shrublands and an abandoned field, hydrological characteristics were determined in relation to spatial patterns in soil, vegetation and morphology. During the experiments on shrubland, runoff at fine scales occurred shortly after the start of the experiments. Rapid and non-uniform infiltration near vegetation clusters, related to preferential flowpaths of water, was observed. This prevented the development of runoff over distances larger than 1 metre. The surface redistribution of water was not observed on the abandoned land. Here, little vegetation structure was present and infiltration rates were high below crusts as well as stones. We suggest that the development of spatial structures in vegetation and soil forms a positive feedback with non-uniform infiltration and increased soil water retention. The assessment of land degradation could benefit greatly from acknowledging the importance of non-uniformity in hydrological processes. Furthermore, the presented measurements indicate that in discontinuous environments runoff measurements at fine scales cannot be extrapolated directly. In these environments a scaled approach needs to be adopted emphasizing the importance of different hydrological processes at different scales.     

Infiltration of river water to a shallow aquifer investigated with H/He, noble gases and CFCs

Noble gas isotopes (³He, ⁴He, Ne, Ar, Kr, Xe), tritium (³H), chlorofluorocarbons (CFCs) and dissolved oxygen (O₂) were seasonally measured in a small groundwater system recharged by infiltration of river water at Linsental, northeastern Switzerland. All Groundwater samples contained an excess of atmospheric noble gases (‘excess air’) usually with an elemental composition equal to air. The concentrations of atmospheric noble gases in the groundwater were used to calculate the excess air component and the water temperature at recharge. The noble gas temperatures (NGTs) in the boreholes close to the river vary seasonally, however, the average NGT of all samples lies close to the mean annual temperature of the river water. Groundwater ages were calculated using the tritium/helium-3 (³H/³He) dating method. The water ages of the samples obtained near the river depend on the amount of recently infiltrated river water and are young during times of active river discharge. In contrast, the mean water age of about 3 years of the deep aquifer remained nearly constant over the sampling period. The observed CFC-11 (CFCl₃) and CFC-12 (CF₂Cl₂) concentrations are significantly higher than the atmospheric equilibrium concentrations and therefore CFCs do not provide any direct information on the residence time of the groundwater. Nevertheless, the CFC excess in the groundwater shows a linear increase with the ³H/³He age. Additionally, both accumulation of radiogenic He (⁴He_rad) and O₂ consumption are strongly correlated with residence time. All these correlations can be interpreted either in terms of mixing of recently infiltrated river water with older groundwater or in terms of accumulation/consumption rates.     

Trace element compositions of minerals in garnet and spinel peridotite xenoliths from the Vitim volcanic field, Transbaikalia, eastern Siberia

Peridotite xenoliths from the Bereya alkali picrite tuff in the Vitim volcanic province of Transbaikalia consist of garnet lherzolite, garnet–spinel lherzolite and spinel lherzolite varieties. The volcanism is related to the Cenozoic Baikal Rift. All peridotites come from pressures of 20–23 kbar close to the garnet to spinel peridotite transition depth, and the presence of garnet can be attributed to cooling of spinel peridotites, probably during formation of the lithosphere. The peridotites show petrographic and mineral chemical evidence for infiltration by an alkaline silicate melt shortly before their transport to the Earth's surface. The melt infiltration event is indicated petrographically by clinopyroxenes which mimic melt morphologies, and post-dates outer kelyphitic rims on garnets which are attributed to an isochemical heating event within the mantle before transport to the Earth's surface. Single-mineral thermometry gives reasonable temperature estimates of 1050±50°C, whereas two-mineral methods involving clinopyroxene are falsified by secondary components in clinopyroxene introduced during the melt infiltration event. Excimer Laser–ICP-MS analysis has been performed for an extensive palette of both incompatible and compatible trace elements, and manifests the most thorough dataset available for this rock type. Orthopyroxene and garnet show only partial equilibration of trace elements with the infiltrating melt, whereas clinopyroxene and amphibole are close to equilibration with the melt and with each other. The incompatible element composition of the infiltrating melt calculated from the clinopyroxene and amphibole analyses via experimental mineral/melt partition coefficients is similar to the host alkali picrite, and probably represents a low melt fraction from a similar source during rift propagation. The chemistry and chronology of the events recorded in the xenoliths delineates the series of events expected during the influence of an expanding rift region in the upper mantle, namely the progressive erosion of the lithosphere and the episodic upward and outward propagation of melts, resulting in the evolution of the Vitim volcanic field.     

连续与间歇积水入渗对比试验研究

以黄土沟壑区典型黑垆土连续与间歇入渗对比试验为依据,分析了两者在入渗率、入渗量、水分再分布过程、湿润锋推进速度及推进深度等方面的差异,探讨了间歇积水入渗机理。