NAO-1: Lunar Highland Soil Simulant Developed in China

A new lunar highland soil simulant, NAO-1, has been created in National Astronomical Observatories (NAO), Chinese Academy of Sciences. This simulant was produced by gabbro, which includes large quantity of feldspar (An>90). The simulant’s chemical composition, mineralogy, particle-size distribution, density, angle of internal friction, and cohesion have been analyzed and results demonstrated that most characteristics of NAO-1 are similar with lunar highland soil samples. NAO-1 will benefit the scientific and engineering research of lunar soil.     

超声去除土壤中石油污染物的效果

土壤被石油污染之后,使得地里的植物不容易生长的很好,在他们之间存在食物的关系,这就会让人类的身体状况受到影响,所以,我们要实施有用的方法去进行治理。目前,根据研究数据统计,通过超声处理的办法来加强石油的污染物把土壤表面的污染物解决吸收,在超声的功率越来越强下,使得黏土的颗粒所吸附的稠油的数量就会减少,尤其是超声空化的作用,能够把土壤中所残存的油族等组分给去掉,其结果很是显著。     

浅谈土钉墙技术在边坡支护工程中应用

随着建设的飞速发展,深基坑越来越多。土钉墙作为一种支护形式,由于其结构轻、柔性大、施工设备简单、经济效益好等特点而被广泛应用与基坑支护工程中。本文对土钉墙的技术原理进行了简单的分析,并结合具体工程实例行进了土钉墙施工组织设计。     

Improvement Properties of Cohesion-Less Soil Using Recycled Bassanite

Solid waste management is a serious problem over the world. Therefore, reduction, re-use and recycling of waste have become major issues in recent days. Gypsum waste plasterboard is considered one example of these waste materials. This study evaluates the use of recycled bassanite, which is derived from gypsum waste plasterboard, to enhance the performance of two types of cohesion-less soil. Recycled bassanite was utilized as a stabilizing agent to improve both compressive and splitting strengths of the tested soil. The effect of bassanite content, soil type, water content and curing time were investigated to explore the behavior of treated soil with recycled bassanite. Test results showed that increase of bassanite content is associated with increase in optimal moisture content, while no significant increase in the dry unit weight was observed. Both compressive and splitting tensile strengths enhanced with the additives of recycled bassanite. The increase of bassanite content had a more significant effect on the compressive strength compared with the effect on tensile strength. The use of recycled bassanite to enhance the strength of sandy soil had a more significant effect compared with silty soil. The effect of curing time on the strength of treated samples was more significant in early curing ages compared with late curing ages. The strength decreased significantly in case of stabilized samples prepared with water content at the wet-side of the compaction curve. However, insignificant decrease in the strength of the stabilized sample was detected with moisture content at the dry-side of compaction curve. This research meets the challenges of our society to reduce the quantities of gypsum wastes, producing useful material from waste materials that will help to a sustainable society.     

我国城市水土保持几个问题的讨论

我国城市水土保持经过近20年的发展,已经成为水土保持的一个重要领域。在当前城市化高速发展的情况下,新时期的城市水土保持应在内涵和外延上进一步拓展,充分发挥城市水土保持的生态服务功能、景观与游憩功能、防灾避险功能。以生态学理论为指导、城市水土保持资源化、城市水土保持与城市生态文明建设密切结合,将是城市水土保持发展的必然趋势。     

Soil and water quality assessment along the Red Sea coast,Egypt

The paper reports an assessment of the soil and water in the coastal strip between Marsa Alam and Shalateen at the southern part of the Red Sea coast of Egypt. There is limited potential for agricultural development. There is a need for water re-use and some potential for tourism.     

Short-term dynamics of soil chemical parameters after application of alperujo in high-density drip-irrigated olive groves in Argentina

Two-phase olive oil mills generate a semi-solid waste made of olive pulp, olive stone, and vegetation water commonly called ‘alperujo’. Lack of disposal alternatives drives many Argentinean olive oil producers to apply it directly as soil amendment to the olive orchards. Even though this practice has been widely evaluated in Mediterranean countries, there is little agreement on the environmental impact that it may produce. In this work a surface layer of alperujo was applied to a high-density, drip-irrigated olive orchard, and different parameters were monitored. This report summarises the dynamics of soil chemical properties during the first 200 days after application. The results obtained showed that soil amended with alperujo increased total organic matter (OM), nitrogen (N) and available potassium (K), without affecting soil electrical conductivity (EC), pH and C/N ratio. The results suggest that surface application of alperujo may represent an attractive alternative to disposal under conservationist management. Further research evaluating long term effects on chemical and biological indicators must be performed to ensure the sustainability of alperujo as soil amendment.     

Granulometry,cluster analysis and spatial distribution of manganese contaminated soils,Kgwakgwe, southeastern Botswana

The particle size distribution (PSD) of 400 Mn contaminated soil samples was established, and generated data were statistically analysed and spatially presented. The PSD for the 53 µm – 4 µm size fraction soil samples ranged from 11.05 to 100 wt %, whereas that for < 4 µm was from 0.3 to 30 wt %. Texturally, samples were dominantly silt loam, although silt and sandy loam were also present, as well as loam, loamy sand and clay classes. Six clusters were identified with cluster one being the most dominant occurring in sandy loam, silt loam and loamy sand. The < 53 µm fraction had three dominant areas, and the < 4 µm fraction had several unevenly presented populations as reflected in the maps. Because of its spatial distribution, the < 4 µm fraction may pose hazards to human health. Furthermore, predominance of Mn limits land use to subsistence agriculture with possibly low crop yield.     

Lead,Cadmium And Zinc Accumulation On Soil And Vegetation Along Some Selected Major Roads Of Eastern Cape

Surface soil and grass samples were collected in triplicates from seven locations perpendicular to three major roads in Eastern Cape. Total and available lead, cadmium and zinc were determined in the soil samples and total elements were determined in grass. Lead, cadmium and zinc concentrations declined with distance from road traffic. Significant correlation was also established between available elements in soil and in grass. Levels of total and available elements in the soils ranged from 1167-10834 v µg v g m 1 and from 200-" 5734 v µg v g m 1 , respectively. The levels of the element in grass varied between 200 v µg v g m 1 and 3900 v µg v g m 1 . Total and available cadmium levels in soil although lower than the levels are also significant with values ranging from 17-"2833 v µg v g m 1 and from 27 v µg v g m 1 and from 27-1867 v µg v g m 1 , respectively. The cadmium levels in grass varied between 7 v µg v g m 1 and 1100 v µg v g m 1 . The total and available zinc levels in soil ranged from 2833-8334 v µg v g m 1 and from 533-3600 v µg v g m 1 . The levels in grass varied between 0 and 2800 v µg v g m 1 . The degree of pollution measured would constitute a threat to livestock. Motor traffic appears to be the main source of the elements.     

Laboratory measurement of hydraulic conductivity functions of two unsaturated sandy soils during drying and wetting processes

The importance of applying unsaturated soil mechanics to geotechnical engineering design has been well understood. However, the consumption of time and the necessity for a specific laboratory testing apparatus when measuring unsaturated soil properties have limited the application of unsaturated soil mechanics theories in practice. Although methods for predicting unsaturated soil properties have been developed, the verification of these methods for a wide range of soil types is required in order to increase the confidence of practicing engineers in using these methods. In this study, a new permeameter was developed to measure the hydraulic conductivity of unsaturated soils using the steady-state method and directly measured suction (negative pore-water pressure) values. The apparatus is instrumented with two tensiometers for the direct measurement of suction during the tests. The apparatus can be used to obtain the hydraulic conductivity function of sandy soil over a low suction range (0–10 kPa). Firstly, the repeatability of the unsaturated hydraulic conductivity measurement, using the new permeameter, was verified by conducting tests on two identical sandy soil specimens and obtaining similar results. The hydraulic conductivity functions of the two sandy soils were then measured during the drying and wetting processes of the soils. A significant hysteresis was observed when the hydraulic conductivity was plotted against the suction. However, the hysteresis effects were not apparent when the conductivity was plotted against the volumetric water content. Furthermore, the measured unsaturated hydraulic conductivity functions were compared with predictions using three different predictive methods that are widely incorporated into numerical software. The results suggest that these predictive methods are capable of capturing the measured behavior with reasonable agreement.