Red Sea faulting and salt diapirism as a potential geotechnical hazard in Jazan,southwest Saudi Arabia: inferences from gravity data

Natural Hazards - The main objective of this study is to detect the subsurface extension of salt diapirs and structural deformations in the city of Jazan and its suburbs using gravity data. Salt...     

Bringing the other into political ecology: Reflecting on preoccupations in a research field

For all its vitality political ecology often appears to be a project in which work by Anglo‐Americans in particular, if it is not privileged, certainly predominates. This trend reflects wider language and intellectual tendencies in human geography and the social sciences that distort the development of the field by downplaying or obscuring the contributions of many non‐Anglo‐Americans and by naturalizing Anglo‐American assumptions at the heart of research. The latter in turn determine what constitutes ‘good’ work – even as there is no single definition of political ecology. Arguing against this tendency, this paper draws on postcolonial thinking to emphasize the need to reassess and reorient the field as ‘other’ political ecologies are feasible and desirable.     

Entering the field: Examining the relevance of political ecology to the agrarian struggle of Anjuman Muzareen Punjab in Pakistan

The widening empirical and theoretical scope of political ecology has been accompanied by discussions on the coherence and content of the field. While these evaluations necessarily focus on what is included in the conceptual boundaries of political ecology, little is said about what is left out. This paper considers the struggle for land rights by Anjuman Muzareen Punjab, a movement of tenant farmers in Pakistan, to illustrate how changing research priorities, difficulties in crossing theoretical and conceptual boundaries, and geopolitics and research access can hinder the visibility of particular forms of socioenvironmental events in mainstream political ecology scholarship.     

Hydrochemical assessment of groundwater from shallow aquifers in parts of Wadi Al Hamad,Madinah, Saudi Arabia

The present study was carried out in the Mulaylih area which forms a part of Wadi Al Hamad in the Madinah Province of Saudi Arabia. Thirty groundwater samples from agricultural farms were collected and analyzed for various physio-chemical parameters including trace elements. The area is occupied by the Quaternary alluvium deposits which form shallow unconfined aquifers. Evaporation and ion exchange are the major processes which control the major ion chemistry of the area. The extreme aridity has results in high total dissolved solid values (average of 9793.47 mg/l). Trace element concentrations are low and are mainly attributed to geogenic sources (silicate weathering). Na-Cl groundwater type is the main hydrochemical facies found in the area. The waters are found to be oversaturated with calcite/aragonite and dolomite. The average nitrate concentration was found to be 134.10 mg/l and is much higher than the WHO recommended limit of 50 mg/l in drinking water. Their high values are mainly associated with the application of N-fertilizers on the agricultural farms. The average fluoride concentration in the study was found to be 1.54 mg/l. The relation between F and Cl and Cl and Na reveals that the fluoride concentrations are mainly attributed to geogenic sources. A comparison of the groundwater quality with the Saudi drinking water standards shows that the water is unfit for drinking. The high salinity and sodicity of the groundwater make it unfit for irrigation. Principal component analysis resulted in extraction of four principal components accounting for 79.5% of the total data variability and supports the fact that the natural hydrochemical processes (evaporation and ion exchange) control the overall groundwater chemistry.     

Rapid earthquake hazard and loss assessment for Euro-Mediterranean region

The almost-real time estimation of ground shaking and losses after a major earthquake in the Euro-Mediterranean region was performed in the framework of the Joint Research Activity 3 (JRA-3) component of the EU FP6 Project entitled “Network of Research Infra-structures for European Seismology, NERIES”. This project consists of finding the most likely location of the earthquake source by estimating the fault rupture parameters on the basis of rapid inversion of data from on-line regional broadband stations. It also includes an estimation of the spatial distribution of selected site-specific ground motion parameters at engineering bedrock through region-specific ground motion prediction equations (GMPEs) or physical simulation of ground motion. By using the Earthquake Loss Estimation Routine (ELER) software, the multi-level methodology developed for real time estimation of losses is capable of incorporating regional variability and sources of uncertainty stemming from GMPEs, fault finiteness, site modifications, inventory of physical and social elements subjected to earthquake hazard and the associated vulnerability relationships.     

Determination of Cyanuric Acid in Swimming Pool Water and Milk by Differential Pulse Polarography

Cyanuric acid is a suspected gastrointestinal or liver toxicant in humans. Therefore, determination of trace cyanuric acid is very important, in this work a novel, sensitive, and reliable method was developed using differential pulse polarography. Optimum conditions for analytical determination were found to be at a pH of 9.5, Britton–Robinson at a reduction potential of ?105 mV. Experimental results indicate an excellent linear correlation between the peak current and the concentration in the range of cyanuric acid from 0.5 to 27.0 µM (0.06–3.5 µg mL^?1) with a correlation coefficient of 0.997. The limit of detection and limit of quantification were obtained as 0.15 and 0.5 µM (0.02–0.06 µg mL^?1), respectively. The proposed method was successfully applied to the determination of cyanuric acid in pool water and in spiked milk. Cyanuric acid level in swimming pool water was found as 2.54 ± 0.47 µg mL^?1 (19.7 ± 2.29 µM) in swimming pool water for N = 4 and 95% confidence interval. The recoveries were found to be sufficient. Also, the standard deviation of the data was low which shows high accuracy and precision of proposed differential pulse polarographic method. The influences of some other commonly found inorganic salts on the determination of cyanuric acid were also examined. Some interfering species were eliminated using complexing agents, e.g., EDTA.     

Use of electrical resistivity tomography in delineating zones of groundwater potential in arid regions: a case study from Diriyah region of Saudi Arabia

A detailed geophysical investigation in the form of electrical resistivity tomography (ERT) was carried out using the SYSCAL Pro Unit at two locations with a dipole?Cdipole configuration in one of the private farms in Diriyah area of Riyadh, Saudi Arabia with the purpose of delineating the approximate depth of the water-bearing formations. The survey helped in delineating a superficial moist zone at the first site which was mainly due to the seepage from surface water pipes used for irrigating the date palms. At the second site, a potential water-bearing zone was detected starting from a depth of 23 to 46?m. However, an already existing bore well in close vicinity of the site of the second survey showed a water table depth of 85?m, indicating the presence of a layered aquifer. Finally, it was concluded that a shallow bore well drilled up to a depth of 50?C60?meters would be able to tap the water resources of shallow water-bearing horizon discovered at the second site during the survey; however, the yield of the bore well might not be sustainable over a longer period of time. The survey at the first site did not show any promising groundwater potential up to the investigated depth which was around 70?m. The study confirms the usage of ERT surveys for exploring sources of freshwater supplies in arid regions.     

无人艇载水陆一体化测量系统集成优化技术

为提高水陆一体化测量系统的作业精度和性能,开展无人艇载水陆一体化测量系统集成优化技术研究。借助仿真分析手段,对艇型及设备布置进行优化研究,并开展多传感器集成、时间同步、盲区无缝和实时拼接技术研究,设计并集成了无人艇载水陆一体化测量系统。实验表明,无人艇载水陆一体化测量系统获得的水上水下数据的平均垂直误差为0.12m。所提出的无人艇载水陆一体化测量系统集成优化技术是可行的,可为测绘艇和水陆一体化测量系统集成提供理论依据。     

Biodegradation of toxic chemicals in Guayanilla Bay,Puerto Rico

Studies were conducted to assess the factors that may influence the rate and extent of biodegradation of biphenyl, naphthalene, phenanthrene, pentachlorophenol (PCP) and p-nitrophenol in water samples collected from the Guayanilla Bay (18 degrees N; 67.45 degrees W), southwest of Puerto Rico. In vitro studies mediated slow degradation of biphenyl, naphthalene and phenanthrene substrates by natural microbial flora present in the Bay. Addition of KNO(3) as a source of inorganic N greatly enhanced the degradation of phenanthrene but not of naphthalene, suggesting that effects on degradation due to nutrient limitation were compound specific. The rate and extent of degradation of naphthalene and PCP were higher in water samples collected closer to the source of contamination, i.e. the petrochemical complex. The identity of a phenanthrene degrading bacterium, previously identified by conventional phenotypic method (Zaidi et al., Utilizing Nature's Advanced Materials, Oxford Unviersity Press, 1999) as Alteromonas sp., was confirmed by partial DNA sequencing of the small subunit rRNA gene.