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.     

Geochemistry and environmental impacts of retorted oil shale from Jordan

Physical and chemical characterization of spent oil shale (OS) from El-Lajjun area has been carried out and compared with the original OS. The spent shale (SS) is subjected to leaching tests to detect the possibilities of heavy metals released from it into the environment. Standard column leaching experiments have revealed no detectable release of heavy metals to the percolating water. The effectiveness of the SS in removing Pb²⁺ from wastewater has been investigated. The SS is very efficient in removing most of Pb²⁺ where 1 m³ of SS has an efficiency to remove from 64 to 94% of Pb²⁺ from about 1,300 m³ wastewater sample containing 50 ppm Pb²⁺. The efficiency decreases substantially with increasing Pb²⁺ concentration in the wastewater. In real situations, where Pb²⁺ concentration is very low (i.e., less than 5 ppm), the efficiency of the SS is expected to be 100%.     

Groundwater vulnerability assessment and evaluation of human activity impact (HAI) within the Dead Sea groundwater basin,Jordan

Groundwater vulnerability to contamination was determined within the Dead Sea groundwater basin, Jordan, using the DRASTIC model and evaluation of human activity impact (HAI). DRASTIC is an index model composed of several hydrogeological parameters and, in this study, the recharge parameter component was calculated as a function of rainfall, soil permeability, slope percentage, fault system, and the intersection locations between the fault system and the drainage system, based on the hydrogeologic characteristics of hard-rock terrain in an arid region. To evaluate the HAI index, a land use/cover map was produced using an ASTER VNIR image, acquired for September 2004, and combined with the resultant DRASTIC model. By comparing the DRASTIC and HAI indices, it is found that human activity is affecting the groundwater quality and increasing its pollution risk. The land use/cover map was verified using the average nitrate concentrations in groundwater associated with land in each class. A sensitivity analysis was carried out in order to study the model sensitivity. The analyses showed that the depth to water table and hydraulic conductivity parameters have no significant impact on the model, whereas the impact of vadose zone, aquifer media, and recharge parameters have a significant impact on the DRASTIC model.     

大泷六线鱼仔鱼饥饿试验及不可逆点的研究

摘要：利用人工孵化得到的大泷六线鱼（Hexagrammos otakii Jordan et Starks）初孵仔鱼,在水温16±0.5℃,盐度31条件下,研究了饥饿对大泷六线鱼前期仔鱼生长的影响,并确定仔鱼的初次摄食饥饿不可逆点（PNR）。结果表明,仔鱼3日龄开口摄食,卵黄于7日龄消耗完毕,油球于8日龄消耗完毕,混合营养期为5-6天,饥饿对仔鱼卵黄吸收速度影响显著（P＜0.05）,对油球的吸收在仔鱼开口前影响不显著（P＞0.05）,仔鱼开口后影响显著（P＜0.05）。摄食仔鱼生长呈线性增加,饥饿仔鱼生长呈现先升高后降低的趋势。仔鱼饥饿不可逆点出现在8日龄和9日龄之间。     

约旦河跨境水冲突的地缘环境研究

随着气候变化、人口增长和经济发展,全球水资源供需矛盾日益突出,国际河流跨境水冲突不断加剧。地处中东的约旦河是世界上跨境水冲突最严重的河流。1948—2008年约旦河跨境水冲突事件数量占全球总量的1/5,战争性跨境水冲突数量占同级别总量的2/3。本文以地缘价值、地缘关系和地缘结构为模块构建国际河流跨境水冲突地缘环境分析框架,考察约旦河跨境水冲突事件的时空演化及其形成的地缘机制。研究发现,约旦河跨境水冲突的地缘目标集中于水资源战略要地,且按水资源地“主要→核心→次要”空间转移;跨境水冲突事件在时序上呈现从以色列争夺水权为主向域内阿拉伯国家讨还水权为主演化;跨境水冲突地缘体结构中以色列主动发起的跨境水冲突占六成多,域内阿拉伯国家和域外地缘体发起的各约占二成。基于地缘环境分析框架的研究得出以下结论：约旦河流域区位的地缘价值吸引域外大国直接介入,促成跨境水冲突向有利于美国—以色列利益的方向发展;域内地缘体的“水资源地”竞争地缘关系强于“水量”竞争地缘关系,对约旦河跨境水冲突具有强化作用;以色列作为约旦河地缘结构中的水霸权,对该流域跨境水冲突的基本态势和时空分布格局具有主导作用。     

The Big Circles in Jordan: First absolute ages using rock luminescence surface dating

In this study, we provide the first absolute ages for a Big Circle megalithic structure in Jordan, using rock surface luminescence dating of the buried surface of rocks collected from circle J4 in southern Jordan. Five rocks were used for this study. All rocks showed evidence of previous daylight exposure before being used in the construction of the circle. The exposure was sufficient to bleach the latent luminescence signal to a negligible level compared to the subsequent burial dose. Three rocks gave indistinguishable ages, and were last exposed to daylight in 1500 ± 100 BCE; this is very likely to be the date of circle construction. Two others gave younger ages, indicating later disturbance or reworking. These new results provide very strong evidence for construction during the Late Bronze Age, and refute the earlier hypothesis of construction during Umayyad period (661–750 CE) as a hunting trap.