WATER MOVEMENT CAUSED BY SPREADING SURFACTANTS IN UNSATURATED SYSTEMS OF PARTICLES OF NONUNIFORM SIZE

The movement of water originated by the spreading of two surfactants was analyzed in glass beads as well as on soil systems, both of particles of nonuniform size

The higher difference of surface tension produced in the system by 1 -hexadecanol compared to that of 1-tetradecanol led therefore to a higher amount of water moved. Decreased proportion of the smaller sized particles in glass beads system produced a decrease in the total water moved by both surfactants.

Organic matter acted in soil as a second surfactant in glass beads. This effect was compared in glass beads systems once 1-hexadecanol was evenly distributed among the particles as continuous film, which played a role alike that of organic matter in soil and then a second surfactant 1-tetradecanol was added. These additional surfactant effect diminished the difference between initial and final surface tension (surface tension depression) of the system and so the total water moved.

The soil organic matter (1.7%) modified the water movement curve in the presence of low (0.2g) content of 1-hexadecanol, whereas for high content of either alcohol (0.4g) or low content of 1-tetradecanol content (0.2g) the water movement curves were the same     

Symbiotic N2 Fixation and N Uptake of Yellow and White Lupines Influenced by Spontaneous Rhizobia Infection and Substrate

Abstract

By using soil as substrate, white and yellow lupines (Lupinus albus L., Lupinus luteus L.) assimilated higher N amounts than under quartz sand conditions. This was caused by spontaneous infection of lupines with wild Rhizobia strains and also by an additional N uptake from the soil. In yellow lupines without inoculation in non-sterile soil, only the additional N uptake played a role. Differences in P and K supply as the cause of different N acquisition from soil and quartz sand could be excluded. As compared with white lupines, yellow lupines inoculated with Rhizobia had a high N₂ fixation that exceeded the effect of spontaneous infections. This result as well as the positive effect of spontaneous infections with soil-borne Rhizobia on white lupines indicates insufficient effectiveness of the strains used for inoculation on this plant species.     

Environmental radioactivity of soils and sediments: Egyptian sector of the Nile valley

The activity concentrations of natural ⁴⁰K, ²³²Th, and ²³⁸U in 89 soil and 84 sediment samples collected over the entire Egyptian Nile River basin including the Nile delta are reported based on the results of epithermal neutron activation analysis. The average activity concentrations of ⁴⁰K, ²³²Th, and ²³⁸U equal to 15.3?±?6.6, 15.6?±?11.1 and 220?±?31 Bq/kg, respectively, are significantly lower than those reported for the Upper Continental Crust, World Average Sediments as well as World Average Soils, suggesting the presence of a considerable portion of mafic material, most probably originating from the Ethiopian High Plateau. Their average activity concentrations are statistically the same in soil and sediments, indicating that the Nile sediments and soil material are of the same origin. The main goal of this study was not only to estimate the radiological hazards but also to show the influence of sedimentary material transportable by the Blue Nile from the Ethiopian High Plateau. The different hazard indices like the radium equivalent, gamma index, external hazard as well as the internal hazard show a low radiological exposure either on direct contact or if local mud bricks are used in the construction of dwellings.     

A preliminary approach of dynamic identification of slender buildings by neuronal networks

The study of the dynamic behavior of slender masonry structures is usually related to the preservation of the historic heritage. This study, for bell towers and industrial masonry chimneys, is particularly relevant in areas with an important seismic hazard. The analysis of the dynamic behavior of masonry structures is particularly complex due to the multiple effects that can affect the variation of its main frequencies along the seasons of the year: temperature and humidity. Moreover, these dynamic properties also vary considerably in structures built in areas where land subsidence due to the variation of the phreatic level along the year is particularly evident: the stiffness of the soil–structure interaction also varies. This paper presents a study to evaluate the possibility of detecting the variation of groundwater level based on the readings obtained using accelerometers in different positions on the structure. To do this a general case study was considered: a 3D numerical model of a bellower. The variation of the phreatic level was evaluated between 0 and −20 m, and 81 cases studies were developed modifying the rigidity of the soil–structure interaction associated to a position of the phreatic level. To simulate the dispositions of accelerometers on a real construction, 16 points of the numerical model were selected along the structure to obtain modal displacements in two orthogonal directions. Through an adjustment by using neural networks, a good correlation has been observed between the predicted position of the water table and acceleration readings obtained from the numerical model. It is possible to conclude that with a discrete register of accelerations on the tower it is possible to predict the water table depth.     

Nuklearpharmaka — Ihre Entwicklung,Präparation und Anwendungsmöglichkeiten

Radioaktiv markierte Präparate haben in denletzten Jahren in schnell zunehmendem Maße Eingang in die klinische Medizin gefunden. Sie sind beieiner Reihe von Indikationen schon jetzt außerordentlich wertvolle Hilfsmittel bei der Diagnose, besonders bei der Prüfung von Organfunktionen.     

Development of Resin Membranes as a Sensitive Indicator of Heavy Metal Toxicity in the Soil Environment

Abstract

Ion exchange resins in contact with soil can act as a sink for metal cations, thereby simulate the action of plant roots. Ion exchange resins in membrane form offer additional advantages in ease of use and handling. A procedure was developed to assess the bioavailability of four heavy metals Cd, Cr, Ni and Pb via direct in soil burial. A growth chamber experiment with three representative crops (oats, radish and lettuce) was set up to determine the phytotoxic levels of the four heavy metals. The critical levels varied widely from crop to crop, and soil to soil. Lettuce was most sensitive to high concentration of metals. The toxic effects are more pronounced on sandier textured soils.     

基于SVM的固化土无侧限抗压强度模型

为实现较少试验次数下固化土无侧限抗压强度(qu)的准确预测, 提出了基于支持向量机(SVM)的固化土qu的预测模型. 以固化剂各组分掺入比、龄期、初始含水量、固化剂掺量等因素为输入量, 固化土的qu作为输出量, 以径向基为核函数, 采用网格搜索法和交叉验证法进行参数优化, 建立了基于SVM的固化土qu的预测模型. 算例分析表明: 该模型适用于任意条件下固化土qu的精确预测, 且在较小试验成本下实现与响应面法相当的预测精度.     

Influence of Earthworms on the Sulfur Turnover in the Soil

Abstract

The effects of earthworm activity on the concentration and isotopic composition of total sulfur in soils was investigated using batch experiments. Two ecologically different lumbricid species, the anecic Lumbricus terrestris and the endogeic Aporrectodea caliginosa, were used. The earthworms were fed birch leaves, beech leaves, cattle manure or mixed plant litter. All food sources differed isotopically (δ³⁴S) from the soil (Parabraunerde). As a reference, one experiment was carried out without additional food.

The experimental results show, that both earthworm species influence the total S-content and the δ³⁴S-values in the soil by digestion of the different food sources. The differences in the total S-content of the earthworm tissues and in the S-isotopic composition of the casts can be attributed to the ecological differences between the earthworm species.     

15N-Traceruntersuchungen zum Mechanismus der N2O-Bildung in Böden

Nitrous oxide is a potential environmental hazard responsible for the green house effect and the destruction of the ozone layer in the lower stratosphere. Biological denitrification under anaerobic conditions in soils results in the formation of both N₂O and N₂, whereby highly nitrogen-fertilized agricultural soils contribute to a considerable extent of the N₂O emission. Latest results in the literature indicate that nitrous oxide can also be formed as a byproduct of the microbial nitrification. This is of importance for soils in central Germany because of the non-existence of typical denitrification conditions in a semiaride climate.

This study was conducted to measure the path of N₂O formation in Haplic Phaeozen: using [¹⁵N] ammonium and [¹⁵N] nitrat and a GC-MS aided incubation system. The kinetic isotope method was used to evaluate the experimental data. The results are:

- Under anaerobic conditions (～ 90% of the water holding capacity = WHC) N₂O originates mainly from the nitrate pool by denitrification.

- As expected, the N₂O formation is low under aerobic conditions (～ 80% WHC) but the gas originates directly from the ammonium and not from the nitrate pool, probably as a byproduct of the nitrification process.     

Calibration Curve with Improved Limit of Detection for Cadmium in Soil: An Approach to Minimize the Matrix Effect in Laser-Induced Breakdown Spectroscopic Analysis

The present article describes a working or combined calibration curve in laser-induced breakdown spectroscopic analysis, which is the cumulative result of the calibration curves obtained from neutral and singly ionized atomic emission spectral lines. This working calibration curve reduces the effect of change in matrix between different zone soils and certified soil samples because it includes both the species' (neutral and singly ionized) concentration of the element of interest. The limit of detection using a working calibration curve is found better as compared to its constituent calibration curves (i.e., individual calibration curves). The quantitative results obtained using the working calibration curve is in better agreement with the result of inductively coupled plasma–atomic emission spectroscopy as compared to the result obtained using its constituent calibration curves.