Initial phase of the West Scotia mid-oceanic ridge opening     

Al. A. Schreider  A. A. Schreider  J. Galindo-Zaldivar  A. Maldonado  Y. Martos-Martin 《Oceanology》2012,52(4):540-544

The first map illustrating the position of anomaly C12 extending in the NE-SW direction (25°) in the eastern peripheral part of the West Scotia Ridge is presented. Calculations of the paleomagnetic anomalies show that the spreading initiated in the period corresponding to Chron C12r (31.116?C33.266 Ma ago). Chron C11r (30.217?C30.627 Ma ago) was marked by a 200 km northwestward jump of the spreading axis. The calculation of the Euler poles and the rotation angles made it possible to reconstruct the zone of the initial breakup between South America and the Antarctic Peninsula along the western periphery of the continental Terror Rise.  相似文献   

Virtual dipole moment variations through the Proterozoic-Phanerozoic eons     

A. A. Schreider  Al. A. Schreider  P. Varga  C. Denis 《Oceanology》2012,52(4):545-549

The international bank of virtual dipole moment (VDM) data, combined with materials from recent publications (3384 values in total), served as a basis for the analysis of the VDM??s distribution through the Proterozoic and Phanerozoic eons (0?C2.6 Ga). The VDM distribution obtained by the method of a moving average exhibits a positive linear trend from 3.7 × 10²² Am² 2.6 Ga ago to 5.8 × 10²² Am² at present. Against the background of this linear growth, fluctuations with a periodicity of approximately 390 Ma are defined. The obtained data substantially specify the available data on the behavior of the magnetic field during the Proterozoic and Phanerozoic eons and should be taken into consideration for modeling the physical processes in the development of the Earth in the geological past and predicting its ecological and energetic evolution in the future.  相似文献   

Supercritical Fluid CO2 Technique for Destruction of Pathogenic Fungal Spores in Solid Clinical Wastes          下载免费PDF全文

Efaq A. Noman  Nik N. N. A. Rahman  Mohammad Shahadat  Hideyuki Nagao  Adel Al‐Gheethi  Tengku N. T. Lah.  Abdul K. M. Omar 《洁净——土壤、空气、水》2016,44(12):1700-1708

  相似文献   

Hazards resulting from hydrological extremes in the upstream catchment of the Prut River     

F. Corduneanu  D. Bucur  S. M. Cimpeanu  I. C. Apostol  Al. Strugariu 《Water Resources》2016,43(1):42-47

Taking into account the fact that during the last decades domestic readers were poorly familiar with the hydrology of this region, it was considered appropriate to study the extreme situations within the Prut basin. By means of very simple mathematical calculation we have highlighted the role of reservoirs in change of relationships between extreme rainfall and floods/droughts, estimate the confidence degree of these estimations, etc. The Prut watershed is characterized by a temperate-continental climate with excessive influences in the middle and lower parts. Probabilistic analysis of the annual maximum flow indicates high values in the summer. The high flows recorded in 2005, 2008, and 2010 were caused by the most serious floods for the last 35 years. The maximum flow values had an exceeding probability of 2–10%, which explained the frequency of the phenomenon. Only the historical value (4240 m³ s^–1) at Radauti-Prut exceeded the flow rate with 1% probability. The results obtained for the hydrometric station located downstream underlined the role of Stanca–Costesti Accumulation Lake in flood protection. Simple linear regression identified the strength of the relationship between the predictor variable (total monthly rainfall) and the criterion variable (average monthly flow). The indicator used in this study to highlight the size effect, R ² (the regression coefficient), is based on the degree of association between variables and describes the percentage of variability explained by each variable in relation to the other. The results indicated a large effect size at the Radauti–Prut station that decreased gradually downstream, as a result of the flow regularization function played by the reservoir. The minimum flow study revealed 7 consecutive years with drought, from 1982–1988. In the current period, the extremely severe drought began in the late autumn of 2011 and was maintained at the end of the winter, summer, and autumn of 2012.  相似文献   

Monitoring of 45 pesticides in Lebanese surface water using Polar Organic Chemical Integrative Sampler (POCIS)     

Al Ashi Aisha  Wael Hneine  Samia Mokh  Marie-Hélène Devier  Hélèn Budzinski  Farouk Jaber 《Ocean Science Journal》2017,52(3):455-466

The aim of this study is to assess the dissolved concentration of 45 pesticides in the surface waters of the Lebanese Republic using Polar Organic Chemical Integrative Sampler "POCIS". All of the sampling sites are located in the major agricultural land areas in Lebanon. POCIS (n = 3) were deployed at Ibrahim River, Qaraoun Lake and Hasbani River for a duration of 14 days. The total concentration of pesticides ranged from not detected (nd) to 137.66 ng.L^-1. Chlorpyrifos, DDE-pp, diazinon and Fenpropathrin were the most abundant compounds. Qaraoun Lake and Hasbani River were found to be more polluted than Ibrahim River, since they receive large amounts of waste water derived from nearby agricultural lands and they had the lowest dilution factor. The aqueous average concentration of the target compounds were estimated using sampling rates obtained from the literature. Comparison between Time Weighed Average concentrations "TWA" using POCIS and spot sampling is presented. Results showed that POCIS TWA concentrations are in agreement with spot sampling concentrations for Ibrahim and Hasbani Rivers. The toxicity of the major detected pesticides on three representative aquatic species (Daphnia magna, Scenedesmus quadricauda and Oncorhynchus mykiss) is also reported.  相似文献   

<Emphasis Type="Italic">Suraqalatia brasieri</Emphasis> n.gen., n.sp. (larger foraminifera) from the Maastrichtian of Sulaimani area in northern Iraq     

M. Görmüş  F. A. Ameen Lawa  Q.A.M. Al Nuaimy 《Arabian Journal of Geosciences》2017,10(16):365

Suraqalatia brasieri n.gen., n.sp. from the family Dicyclinidae Loeblich and Tappan 1964 occurs on the Maastrichtian carbonate platform of northern Iraq. The new genus is recognizable by its large very compressed conical test, up to 55–70 mm in diameter, to 0.3–1.6 mm in thickness, planspiral cooling having very small proloculus in the initial part and later circular chambers including numerous chamberlets with an agglutinated wall. Suraqalatia brasieri n.gen., n.sp. is associated with textulariids, miliolids and rotaliids as Loftusia elongata Cox, L. morgani Douvillé, Orbitoides medius d’Archiac, O. megaloformis Papp & Kupper, O. gruenbachensis Papp, O. apiculatus Schlumberger, Omphalocyclus macroporus (Lamarck), Siderolites calcitrapoides Lamarck, Sirtina orbitoidiformis Brönnimann & Wirz. The associated macrofauna comprises large and rich giant rudists (Preradiolites sp.), other bivalves (Gryphaea sp. and Glycymeris sp.), gastropods (Acteonella sp.), echinoderms and corals. The fauna indicates shallow marine carbonate platform conditions within the Maastrichtian green house. It is also worth mentioning that the new genus has only been recorded from the Maastrichtian age.  相似文献   

Illuminating and optimising a three‐dimensional model of an oil shale seam and its volume distribution using the transient electromagnetic induction method,central part of Jordan          下载免费PDF全文

Jafar Sadi Abu Rajab  Eid Al Tarazi 《Geophysical Prospecting》2018,66(3):603-625

The oil shale exploration program in Jordan is undertaking great activity in the domain of applied geophysical methods to evaluate bitumen‐bearing rock. In the study area, the bituminous marl or oil shale exhibits a rock type dominated by lithofacies layers composed of chalky limestone, marls, clayey marls, and phosphatic marls. The study aims to present enhancements for oil shale seam detection using progressive interpretation from a one‐dimensional inversion to a three‐dimensional modelling and inversion of ground‐based transient electromagnetic data at an area of stressed geological layers. The geophysical survey combined 58 transient electromagnetic sites to produce geoelectrical structures at different depth slices, and cross sections were used to characterise the horizon of the most likely sites for mining oil shale. The results show valuable information on the thickness of the oil shale seam at 3.7 Ωm, which is correlated to the geoelectrical layer between 2‐ and 4 ms transient time delays, and at depths ranging between 85 and 105 m. The 300 m penetrated depth of the transient electromagnetic soundings allows the resolution of the main geological units at narrow resistivity contrast and the distinction of the main geological structures that constrain the detection of the oil shale seam. This geoelectrical layer at different depth slices illustrates a localised oil shale setting and can be spatially correlated with an area bounded by fold and fault systems. Also, three‐dimensional modelling and inversion for synthetic and experimental data are introduced at the faulted area. The results show the limitations of oil shale imaging at a depth exceeding 130 m, which depends on the near‐surface resistivity layer, the low resistivity contrast of the main lithological units, and the degree of geological detail achieved at a suitable model's misfit value.  相似文献   

Status of Water Quality in King Talal Reservoir Dam,Jordan     

Ahmed A. Al-Taani  Nazem M. El-Radaideh  Wesam M. Al Khateeb 《Water Resources》2018,45(4):603-614

This work intends to monitor and assess the current water quality conditions at King Talal Dam (KTD), Jordan, based on vertical profiles and longitudinal surveys. While the surface distribution of water quality parameters in KTD varied spatially, their variations showed no distinct trends. Lateral and horizontal variations in water quality in KTD are probably linked with photosynthesis, sampling period, closeness to Zarqa River and Wadi Rmemeen, and water depths, among other factors. The vast majority of water quality parameters in KTD dammed reservoir showed vertical profiles that either decrease slightly with increasing depth from the surface (temperature and dissolved oxygen) or remain relatively unchanged (major ions, trace elements). These results suggest that water has probably been vertically mixed. Data also demonstrated rock weathering as a dominant process governing the water chemistry of KTD reservoir water. Based on chlorophyll- a classification of Forsberg and Ryding [19], KTD reservoir is in a mesotrophic-eutrophic condition. Evaluation of water quality for irrigation use revealed that KTD reservoir water is suitable for irrigation purposes, except for Na% and total hardness.  相似文献   

Fluvial suspended sediment yields over hours to millennia in the High Arctic at proglacial Lake Linnévatnet,Svalbard          下载免费PDF全文

Erik Schiefer  Darrell Kaufman  Nicholas McKay  Michael Retelle  Al Werner  Steve Roof 《地球表面变化过程与地形》2018,43(2):482-498

Sediment yield can be a sensitive indicator of catchment dynamics and environmental change. For a glacierized catchment in the High Arctic, we compiled and analyzed diverse sediment transfer data, spanning a wide range of temporal scales, to quantify catchment yields and explore landscape response to past and ongoing hydroclimatic variability. The dataset integrates rates of lake sedimentation from correlated varve records and repeated annual and seasonal sediment traps, augmented by multi‐year lake and fluvial monitoring. Consistent spatial patterns of deposition enabled reconstruction of catchment yields from varve‐ and trap‐based fluxes. We used hydroclimatic data and multivariate modeling to examine annual controls of sediment delivery over almost a century, and to examine shorter‐term controls of sediment transfer during peak glacier melt. Particle‐size analyses, especially for annual sediment traps, were used to further infer sediment transfer mechanisms and timing. Through the Medieval Warm Period and Little Ice Age, there were no apparent multi‐century trends in lake sedimentation rates, which were over three times greater than those during the mid‐Holocene when glaciers were diminished. Twentieth‐century sedimentation rates were greater than those of previous millennia, with a mid‐century step increase in mean yield from 240 to 425 Mg km^?2 yr^?1. Annual yields through the twentieth century showed significant positive relations with spring/summer temperature, rainfall, and peak discharge conditions. This finding is significant for the future of sediment transfer at Linnévatnet, and perhaps more broadly in the Arctic, where continued increases in temperature and rainfall are projected. For 2004–2010, annual yields ranged from 294 to 1330 Mg km^?2 yr^?1. Sediment trap volumes and particle‐size variations indicate that recent annual yields were largely dominated by spring to early summer transfer of relatively coarse‐grained sediment. Fluvial monitoring showed daily to hourly sediment transfer to be related to current and prior discharge, diurnal hysteresis, air temperature, and precipitation. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Insight into sediment transport processes on saline rangeland hillslopes using three‐dimensional soil microtopography changes          下载免费PDF全文

Sayjro K. Nouwakpo  Mark A. Weltz  Kenneth C. McGwire  Jason C. Williams  Al‐Hamdan Osama  Colleen H.M. Green 《地球表面变化过程与地形》2017,42(4):681-696

In arid and semi‐arid rangeland environments, an accurate understanding of runoff generation and sediment transport processes is key to developing effective management actions and addressing ecosystem response to changes. Yet, many primary processes (namely sheet and splash and concentrated flow erosion, as well as deposition) are still poorly understood due to a historic lack of measurement techniques capable of parsing total soil loss into these primary processes. Current knowledge gaps can be addressed by combining traditional erosion and runoff measurement techniques with image‐based three‐dimensional (3D) soil surface reconstructions. In this study, data (hydrology, erosion and high‐resolution surface microtopography changes) from rainfall simulation experiments on 24 plots in saline rangelands communities of the Upper Colorado River Basin were used to improve understanding on various sediment transport processes. A series of surface change metrics were developed to quantify and characterize various erosion and transport processes (e.g. plot‐wide versus concentrated flow detachment and deposition) and were related to hydrology and biotic and abiotic land surface characteristics. In general, erosivity controlled detachment and transport processes while factors modulating surface roughness such as vegetation controlled deposition. The extent of the channel network was a positive function of slope, discharge and vegetation. Vegetation may deflect runoff in many flow paths but promoted deposition. From a management perspective, this study suggests that effective runoff soil and salt load reduction strategies should aim to promote deposition of transported sediments rather than reducing detachment which might not be feasible in these resource‐limited environments. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献