Free Amino Acids Content in Some Halophytes under Salinity Stress in Arid Environment,Jordan

The variation in free amino acids concentration was examined in halophytes under salt stress conditions during spring and autumn in an arid environment, Jordan. The experiment was conducted in the southern region of the Jordan valley, using four different halophytes namely: Atriplex halimus, Atriplex nummularia, Tamarix aphylla L., and Portulaca oleracea L. Free amino acid concentrations showed changeable patterns under salinity stress conditions compared to the non‐stress (control) with respect to plant species and seasonal variation. In general, the amino acid pool during the spring experienced increases in A. halimus with increasing salinity; and decreased in A. nummularia, P. oleracea L., and T. aphylla L., respectively. Whereas, during the autumn, the overall amino acids decreased in A. halimus and A. nummularia, and increased in T. aphylla L. and P. oleracea with increasing salinity. The amino acid pool concentrations of A. halimus L. during the autumn was similar to that in spring under stress condition. Similarly, T. aphylla L. and P. oleracea showed higher rates in the autumn. In contrast, A. nummularia L. exhibited a slight increase in amino acid composition in the autumn under stress conditions. The plantation of salt tolerant plants such as halophytes in saline sodic soils showed an effective decline in soil salinity and can be recommended to be used as a bioreclamation method instead of the traditional leaching method, which requires large amount of fresh water.     

Impact of biochar,bentonite, and compost on physical and chemical characteristics of a sandy soil

In this study, bentonite (Ben), compost (Com), and biochar (Bio) were used as soil amendments to enhance sandy soil physical properties. A soil column experiment was conducted in a laboratory. Application rates were 3% (weight/weight) of Bio (T₁), Ben (T₂), and Com (T₃). Furthermore, mixtures 1.5% and 1.5% of Bio and Ben (T₄), Ben and Com (T₅), and Bio and Com (T₆), and a mixture 1%, 1%, and 1% of Bio, Ben, and Com (T₇) in addition to control treatment were adopted. The mixtures of amendments and sandy soil were concentrated at the top 10 cm of columns. Results revealed that the cumulative evaporation was reduced by 2.3% and 5.7% as a result of using T₃ and T₅, respectively. However, the remaining treatments enhanced the cumulative evaporation. The application of amendments increased the capacity of the soil to maintain water by 35.4%, 24.4%, 13.3%, and 10.2%, for soils treated with T₅, T₃, T₇, and T₄, respectively. The water content at field capacity had the highest increase in the top 10 cm when treatment T₃ was used. Although T₃ (compost) was the most efficient for enhancing soil physical properties, this study recommends T₅ and T₇ to improve hydraulic properties of sandy soils. This is due to the fact that biochar and bentonite remain in the soil for a longer period and resist biodegradation while compost overcomes the negative impact of soil chemical properties as a result of biochar and bentonite additions.     

Managing crop stubble during fallow period for soil water conservation: field experiment and modelling

In the arid and semi-arid environments where the rainfall is limited and variable, fallow period soil moisture conservation using stubble is one of the ways of increasing the soil moisture required for crop sowing and development. However, the effectiveness of moisture conservation using stubble depends on the paddock management, soil water content, and rainfall characteristics. To assess the effect of stubble rate and amount of rainfall on the soil moisture conservation, a two-season field experiment was conducted using four stubble rates (0, 2, 4, 6 t/ha) and two water supply amounts. The soil water dynamics was also analysed using a validated Agricultural Production System Simulator (APSIM). In the relatively wet summer season with a high initial soil water content, the amount of water stored in the 2, 4, and 6 t/ha stubble rate treatment plots was higher than that of the bare plots by 10.4, 15.9, and 17.8 mm, respectively. However, in the summer season with a relatively high amount of in-season water input and low initial soil water content, the soil water storage was increased by 29.4, 35.6, and 43.0 mm, respectively. Comparing the results of the two seasons, the highest increase was observed for the 2 t/ha stubble rate. The amount of conserved soil moisture was found to be the highest when the soil profile water content at the start of the summer-fallow period is low and the amount of rain during the summer season is high. The good agreement between the measured and APSIM-simulated soil water contents (R ² = 0.812), indicates that the model can be used to assess the soil water dynamics under a fallow condition. The APSIM-simulated soil water balance using the weather data of the past 100 years indicated that in a year with low start-of-fallow period soil water content, a 6 t/ha stubble rate can increase the end-of-fallow period soil moisture by up to 60 %.     

Clay mineral variations in Holocene terrestrial sediments from the Indus Basin

We employed X-ray diffraction methods to quantify clay mineral assemblages in the Indus Delta and flood plains since ~ 14 ka, spanning a period of strong climatic change. Assemblages are dominated by smectite and illite, with minor chlorite and kaolinite. Delta sediments integrate clays from across the basin and show increasing smectite input between 13 and 7.5 ka, indicating stronger chemical weathering as the summer monsoon intensified. Changes in clay mineralogy postdate changes in climate by 5–3 ka, reflecting the time needed for new clay minerals to form and be transported to the delta. Samples from the flood plains in Punjab show evidence for increased chemical weathering towards the top of the sections (6–< 4 ka), counter to the trend in the delta, at a time of monsoon weakening. Clay mineral assemblages within sandy flood-plain sediment have higher smectite/(illite + chlorite) values than interbedded mudstones, suggestive of either stronger weathering or more sediment reworking since the Mid Holocene. We show that marine records are not always good proxies for weathering across the entire flood plain. Nonetheless, the delta record likely represents the most reliable record of basin-wide weathering response to climate change.     

Stepwise,earthquake-driven coastal subsidence in the Ganges–Brahmaputra Delta (Sundarbans) since the eighth century deduced from submerged in situ kiln and mangrove remnants

Natural Hazards - This study reconstructs the coastal subsidence over the past 1300&nbsp;years in a mangrove region along the coast of the Ganges–Brahmaputra Delta, an area not affected...     

Rock mass characterization for the underground cavern design of Khiritharn pumped storage scheme

A general approach to rock engineering designing aspects adopted at the Khiritharn Pumped Storage Scheme is described. The scheme involves excavation of three large caverns and tunnels in jointed sandstone within a suture zone in Southeast Thailand. Geological condition and engineering properties of the sandstone were investigated. Strength and modulus properties of the intact rock were determined from laboratory tests and properties of rock mass were empirically estimated for the design analysis in the de.nite study stage on the basis of three rock mass classi.cation systems namely the Rock Mass Rating (RMR), Geological Strength Index (GSI) and a Japanese system (EPDC). While the GSI gives strength and modulus of deformation values slightly higher than the RMR classi.cation, the EPDC gives a lower value of modulus of deformation but comparable rock mass strength value for the level of con.ning pressures at the depth of the cavern excavation. The results of stress analysis and loosening wedge analysis for the cavern excavations suggest favorable excavation condition.     

Simulation of Electrical Conduction in Geomaterials by SPICE

Electrical responses of the subsurface can be used to identify geologic strata, locate anomalies, detect and delineate contamination, among many other applications. All these applications depend on the spatial variations of electrical properties in the subsurface and the resulting flow pattern of electric current. Due to the heterogeneity of the subsurface and complex boundary conditions, three-dimensional electric current flow problems are not easy to analyze, in particular when the response is frequency- and/or time-dependent. In this paper, a method of electric circuit analogy is proposed to simulate the electrical responses of geomaterials using the circuit simulator SPICE. The technique will allow simulation of more complex electrical conduction behavior of geomaterials without much extra effort. The excellent agreement between simulated results and analytical solutions developed for surface geophysical techniques establishes the viability of the method. Limitations of the approach and potential solutions to relax these limitations, and other potential applications of the technique in geosciences are also discussed.     

The quality of water and sediments of street runoff in Amman,Jordan

Metallic content (Cr, Fe, Mn, Cu, Ni, Pb and Cd) of street sediments and street runoff in addition to major inorganic constituents (Ca, Mg, Na, K, HCO₃, Cl, NO₃ and SO₄) of street runoff were determined under semi‐arid conditions. Two sites in the vicinity of Amman during the pluvial year 1998–1999 were chosen for this investigation. A higher quantity of ionic contents was found at site 2 in comparison to site 1 except for iron, which was significantly higher at site 1. This finding was attributed to higher anthropogenic activity and lower rainfall at site 2, which indicates better water quality of street runoff from residential sites than the city centre. The average concentrations of Pb, Cu and Cd in Amman street runoff compared with the highest levels recorded at humid sites of the world as a result the prevailing semi‐arid conditions in the areas investigated. The highest concentrations of all constituents were detected during the first month of sampling, which might be the result of low rainfall, and a long dry period of atmospheric deposition preceding rainfall events. However, high levels of both lead and copper were recorded (below that of iron) which might be attributed to traffic pollution. In contrast, a significant variation between the average concentrations for Cu, Ni and Cr was found in sediments from the two sites. Moreover, a significant difference was detected only for Cu and Mn at each site overtime. The overall pattern of the results suggests that all heavy metal concentrations for street runoff showed a significant variation over time at site 1 whereas only a significant variation was found for Ni at site 2, which can be explained as the result of higher rainfall at site 1 than at site 2. Copyright © 2001 John Wiley & Sons, Ltd.     

人工智能计算技术在新疆干旱区典型绿洲土壤盐分预测中的应用

针对新疆渭干河-库车河三角洲绿洲土壤盐分动态监测中存在的方法问题,首先用灰色关联度模型分析影响形成土壤盐渍化的各因子,并确定其与土壤盐分之间的关联度,然后将人工智能计算技术引入土壤盐分的预测中,经过多次调整网络结构和参数,建立了预测表层土壤盐分的BP神经网络模型和RBF神经网络模型。结果表明：以潜在蒸散量、地下水埋深、地下水矿化度、土壤电导率、总溶解固体、pH值、坡度和土地利用类型8个因素为输入因子,以土壤含盐量为输出因子的BP网络模型和RBF网络模型可有效模拟土壤盐分与其影响因子之间的内在复杂关系,并且有较高的精度。BP网络模型预测误差略低于RBF神经网络。本研究可为分析和预测土壤盐渍化动态规律提供一种有效可行的新途径,是对传统土壤盐分动态研究的补充。     

The Indigenous Aetas of Bataan,Philippines: Extraordinary genetic origins,modern history and land rights

The Aeta Magbukún of Bataan in Luzon, the Philippines remain one of the least known and documented Indigenous tribes. They retain primarily subsistence hunter‐gathering strategies to supply their basic needs. They also strive for recognition of their ancestral connection with, and rights to inhabit their ancestral forest domains, which is threatened by the expansion of agriculture and urban development by non‐Aetas, primarily the majority Tagalog population. The Aeta continue to endure dispossession, poverty and political discrimination through decades of protracted land rights processes. This review explores the potential use of recent genetic evidence in anthropology and human geography to legitimize the Aeta's status as Indigenous people and contradict the perspective of some governments in the Asia Pacific region who question the existence of Indigenous peoples generally, often from fear of land tenure and associated political repercussions. The acquisition and use of genetic research on Indigenous populations is both socially and politically contested through fear of the potential to jeopardize sovereignty claims and lead to biologically‐based discrimination. However, the full implications of the potential use of genetic research to legitimize Indigenous status, as described within this research, has yet to be thoroughly explored. By exploring both the genetic and anthropological evidence using a case study of the Indigenous Aeta, this paper provides a unique approach to building a case for Indigenous rights, occupation, use of ancestral lands, self‐determination, and ultimately, recognition as Indigenous people.