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11.
Syed Hilal Farooq Pintu Prusty Raj Kumar Singh Subhajit Sen Dornadula Chandrasekharam 《Arabian Journal of Geosciences》2018,11(22):709
The contamination of aquifers by fluoride and arsenic is a major cause of concern in several parts of India. A study has thus been conducted to evaluate the extent and severity of fluoride contamination and also its seasonal variability. Two blocks (Purulia-1 and Purulia-2) were considered for this purpose. Twenty groundwater samples (in each season) were collected from tube wells during the pre-monsoon and post-monsoon seasons. In addition to fluoride, groundwater samples were also analyzed for major cations, anions, and other trace elements. The concentration of fluoride shows significant seasonal variation and ranges between 0.94–2.52 and 0.25–1.43 mg/l during the pre-monsoon and post-monsoon seasons, respectively. In pre-monsoon season, more than 40% of the water samples show fluoride concentrations higher than the WHO limit. However, during the post-monsoon season, none of the groundwater sample shows fluoride concentrations higher than the WHO limit. Lesser concentration during the post-monsoon season is attributed to the dilution effect by the percolating rainwater, which has also been reflected in the form of a decrease in concentrations of other elements. The petrographic studies of the rock samples collected from the study area show that the rocks are mainly composed of plagioclase, orthoclase, and quartz with abundant biotite. The weathering and dissolution of biotite plays an important role in controlling the fluoride concentrations in the groundwater of the study area. 相似文献
12.
Mahfuzur Rahman Chen Ningsheng Golam Iftekhar Mahmud Md Monirul Islam Hamid Reza Pourghasemi Hilal Ahmad Jules Maurice Habumugisha Rana Muhammad Ali Washakh Mehtab Alam Enlong Liu Zheng Han Huayong Ni Tian Shufeng Ashraf Dewan 《地学前缘(英文版)》2021,12(6):16-35
Bangladesh experiences frequent hydro-climatic disasters such as flooding.These disasters are believed to be associated with land use changes and climate variability.However,identifying the factors that lead to flooding is challenging.This study mapped flood susceptibility in the northeast region of Bangladesh using Bayesian regularization back propagation(BRBP)neural network,classification and regression trees(CART),a statistical model(STM)using the evidence belief function(EBF),and their ensemble models(EMs)for three time periods(2000,2014,and 2017).The accuracy of machine learning algorithms(MLAs),STM,and EMs were assessed by considering the area under the curve-receiver operating char-acteristic(AUC-ROC).Evaluation of the accuracy levels of the aforementioned algorithms revealed that EM4(BRBP-CART-EBF)outperformed(AUC＞90％)standalone and other ensemble models for the three time periods analyzed.Furthermore,this study investigated the relationships among land cover change(LCC),population growth(PG),road density(RD),and relative change of flooding(RCF)areas for the per-iod between 2000 and 2017.The results showed that areas with very high susceptibility to flooding increased by 19.72％between 2000 and 2017,while the PG rate increased by 51.68％over the same period.The Pearson correlation coefficient for RCF and RD was calculated to be 0.496.These findings highlight the significant association between floods and causative factors.The study findings could be valuable to policymakers and resource managers as they can lead to improvements in flood management and reduction in flood damage and risks. 相似文献
13.
Karin Şeşetyan Laurentiu Danciu Mine B. Demircioğlu Tümsa Domenico Giardini Mustafa Erdik Sinan Akkar Levent Gülen Mehdi Zare Shota Adamia Anooshiravan Ansari Avetis Arakelyan Ayşegül Askan Mher Avanesyan Hektor Babayan Tamaz Chelidze Raffi Durgaryan Ata Elias Hossein Hamzehloo Khaled Hessami Doğan Kalafat Özkan Kale Arkady Karakhanyan Muhammad Asif Khan Tahir Mammadli Mahmood Al-Qaryouti Mohammad Sayab Nino Tsereteli Murat Utkucu Otar Varazanashvili Muhammad Waseem Hilal Yalçın Mustafa Tolga Yılmaz 《Bulletin of Earthquake Engineering》2018,16(8):3535-3566
The Earthquake Model of Middle East (EMME) Project aimed to develop regional scale seismic hazard and risk models uniformly throughout a region extending from the Eastern Mediterranean in the west to the Himalayas in the east and from the Gulf of Oman in the south to the Greater Caucasus in the North; a region which has been continuously devastated by large earthquakes throughout the history. The 2014 Seismic Hazard Model of Middle East (EMME-SHM14) was developed with the contribution of several institutions from ten countries. The present paper summarizes the efforts towards building a homogeneous seismic hazard model of the region and highlights some of the main results of this model. An important aim of the project was to transparently communicate the data and methods used and to obtain reproducible results. By doing so, the use of the model and results will be accessible by a wide community, further support the mitigation of seismic risks in the region and facilitate future improvements to the seismic hazard model. To this end all data, results and methods used are made available through the web-portal of the European Facilities for Earthquake Hazard and Risk (www.efehr.org). 相似文献
14.
Basin analysis study of block 10 in the Say'un-Masilah Basin, Yemen, using a 1D backstripping method
Geohistory analysis was carried out on block 10 in the Say??un-Masilah Basin. The present study is based on the analysis of the well logs of six exploration wells. In the Middle Jurassic to the Middle Eocene, Say??un-Masilah Basin exhibited a complex subsidence history over a period of about 155?Ma. Backstripped subsidence curves are constructed by removing the effects of decompaction to the water column and sediment loads. In the Middle Jurassic, slow subsidence was driven under the effect of sediment load as Kuhlan and Shuqra Formations were deposited as pre-rift deposits. The average total subsidence value of the basement during the deposition of Shuqra Formation was 276?m. The highest subsidence rates during this time are observed northeast of the study area. Rapid subsidence initiated in the Upper Jurassic driven by mechanical extension of the rift, resulting in the deposition of Madbi and Safer Formations, or the so-called Syn-rift deposits. The average tectonic subsidence value of the basements during the deposition of Madbi Formation was 368?m. The highest subsidence rates during this time are observed southwest of the study area. Mechanical extension ceased at about 145?Ma, being replaced by a phase of post-rift subsidence, resulting in more widespread uniform sedimentation, with reduced tectonic subsidence rates forming post-rift deposits represented by Nayfa Formation, Sa??ar Formation, Biyad Formation, and Mahra Group. The total subsidence value of the basement during the deposition of the post-rift sediments increases gradually due to the increase of the sediment load as the rate of deposition was high especially northeast of the area. 相似文献
15.
Tamer Coskun Asuman Yildirim Cigdem Balcik Neslihan Manav Demir Eyup Debik 《洁净——土壤、空气、水》2013,41(5):463-468
In the following study, two methods were employed in which olive mill wastewaters were treated by using reverse osmosis membranes (BW30 and XLE). In the first, wastewater was centrifuged and then passed through the reverse osmosis whereas in the second, an ultrafiltration was placed between the centrifuge and the reverse osmosis. The reverse osmosis experiments were conducted under 10, 15, 20, and 25 bar. The chemical oxygen demand (COD) removal efficiencies under 25 bar were found to be 97.5% for both BW30 and XLE membranes. The highest conductivity removal rates obtained under 25 bar for BW30 and XLE membranes were found to be 95.6 and 96.2%, respectively. As for the highest permeation flux values obtained under 25 bar, they were separately determined for BW30 and XLE as 15.3 and 21.2 L m?2 h?1, respectively. The performances of the membranes were also evaluated in terms of their mass transfer coefficients. According to this, all mass transfer coefficients were found to be <1 and also in proximate to one another; this clearly reflects the results as COD and conductivity removals were approximate and there was a lack of any significant difference, whether ultrafiltration was applied or not. 相似文献
16.
In this study uranium and thorium contents and depositional characteristics of ay rhan bituminous shales（ BS）, west of Ankara（central Anatolia）, are investigated. Samples used were collected from boreholes opened by Park Holding Ltd. A total of 25 samples were taken from bituminous shale levels in boreholes drilled at 6 different locations in the study area. The H rka formation which hosts bituminous shale deposits is a volcanosedimentary sequence and all lithofacies indicate that a lacustrine environment where the water level was continuously changed. In addition to hydrocarbon generation potential, bituminous shales also accumulate significant amount of radioactive elements such as uranium and thorium. The average uranium and thorium concentrations of BS（1.83/2.62 ppm） are much lower than averages of UC, NASK and PAAS（uranium： 2.70/2.66/3.10 ppm; thorium： 8.50/12.30/14.60 ppm）. Low uranium contents in comparison to those of similar lacustrine environments might be attributed to that waters of depositional environment of BS contain low concentration of dissolved uranium and redox conditions were of oxic and dioxic character. Correlation data indicate that U and Th have a similar source and are associated predominantly with clays and phosphates and dominantly with organic material. Radioactive elements in the basin might be derived from Paleozoic granites and metamorphites（e.g. gneiss, schist） which comprise the basement and volcanism which was active in the region throughout the Miocene period. These elements are probably associated with uraniferous phosphate minerals（e.g. autunite, torbernite） which occur in granite, gneiss and schist. BS with average TOC content of 10.96 % shows very good/perfect source rock potential. Positive correlations between Gamma-Ray values and U, Th and K concentrations imply that radioactivity might be originated from these three elements. 相似文献
17.
Ismail Hilal Jamal Eddine Stitou El Messari Jesus Gabriel Moreno Navarro Mohamed Draoui 《Arabian Journal of Geosciences》2017,10(8):197
Preventive protection of surface waters against pollution and the guarantee of the best quality water are the major challenges to provide a sustainable supply of drinking water for the future generations. In this article, we present a hazard mapping application for water contamination of the dam “9 April 1947” located in the northwest of Morocco. This study was motivated by the proliferation of many pollution sources in the study area knowing that the dam feeds the region of Tanger-Asilah that has over 3 million inhabitants. The methodology used was applied for the first time in the city of Freiburg-Ebnet in Germany under the TECHNEAU project funded by the European commission and based on weighting of the different sources of contamination according to three indices: the toxicity index, quantity index, and probability index. The multiplication of the three indices has given us a hazard index named HI varying between 0 and 120 depending on the harmfulness of hazard; the later index has been used to create the final contamination hazard map. The hazard map shows 65% of the watershed area is witnessing a very low danger, 22% of the watershed area is witnessing a low danger, 10% of the watershed area is witnessing a the high danger, and 3% of the watershed area is witnessing a moderate. 相似文献
18.
Osman A. E. Abdalla Mubarik Ali Khalifa Al-Higgi Hilal Al-Zidi Issa El-Hussain Said Al-Hinai 《Hydrogeology Journal》2010,18(6):1437-1445
Seawater intrusion and its spreading rate are the challenging problems in over-pumped coastal aquifers of arid zones like the Batinah region of Oman. The study delineates the saline plume, identifies saline/freshwater zones, and estimates the migration rate of the plume in the Al Khabourah area of the Batinah coast. Time domain electromagnetic surveys, aided by vertical electrical sounding surveys, and seismic refraction methods have defined the locus of the saline/freshwater interface in the area. The current (2007) interface position, when compared with that determined during 2002, indicates a prominent recession in the saline plume and suggests an average annual recession rate of 120 m. This recession may be attributed mainly to the recharging dam of Wadi Al Hawasinah, constructed in 1995, and the enforcement of new water resources legislation. This study reveals the shielding role of the recharging dam to counter advancing saline intrusion. 相似文献
19.
Neogene-Quaternary post-collisional volcanism in Central Anatolian Volcanic Province (CAVP) is mainly characterized by calc-alkaline
andesites-dacites, with subordinate tholeiitic-transitional-mildly alkaline basaltic volcanism of the monogenetic cones. Tepekoy
Volcanic Complex (TVC) in Nigde area consists of base surge deposits, and medium to high-K andesitic-dacitic lava flows and
basaltic andesitic flows associated with monogenetic cones. Tepekoy lava flows petrographically exhibit disequilibrium textures
indicative of magma mixing/mingling and a geochemisty characterized by high LILE and low HFSE abundances, negative Nb–Ta,
Ba, P and Ti anomalies in mantle-normalized patterns. In this respect, they are similar to the other calc-alkaline volcanics
of the CAVP. However, TVC lava flows have higher and variable Ba/Ta, Ba/Nb, Nb/Zr, Ba/TiO2 ratios, indicating a heterogeneous, variably fluid-rich source. All the geochemical features of the TVC are comparable to
orogenic andesites elsewhere and point to a sub-continental lithospheric mantle source enriched in incompatible elements due
to previous subduction processes. Basaltic monogenetic volcanoes of CAVP display similar patterns, and HFS anomalies on mantle-normalized
diagrams, and have incompatible element ratios intermediate between orogenic andesites and within-plate basalts (e.g. OIB).
Accordingly, the calc-alkaline and transitional-mildly alkaline basaltic magmas may have a common source region. Variable
degrees of partial melting of a heterogeneous source, enriched in incompatible elements due to previous subduction processes
followed by fractionation, crustal contamination, and magma mixing in shallow magma chambers produced the calc-alkaline volcanism
in the CAVP. Magma generation in the TVC, and CAVP in general is via decompression melting facilitated by a transtensional
tectonic regime. Acceleration of the extensional regime, and transcurrent fault systems extending deep into the lithosphere
favoured asthenospheric upwelling at the base of the lithosphere, and as a consequence, an increase in temperature. This created
fluid-present melting of a fluid-enriched upper lithospheric mantle or lower crustal source, but also mixing with asthenosphere-derived
melts. These magmas with hybrid source characteristics produced the tholeiitic-transitional-mildly alkaline basalts depending
on the residence times within the crust. Hybrid magmas transported to the surface rapidly, favored by extensional post-collision
regime, and produced mildly alkaline monogenetic volcanoes. Hybrid magmas interacted with the calc-alkaline magma chambers
during the ascent to the surface suffered slight fractionation and crustal contamination due to relatively longer residence
time compared to rapidly rising magmas. In this way they produced the mildly alkaline, transitional, and tholeiitic basaltic
magmas. This model can explain the coexistence of a complete spectrum of q-normative, ol-hy-normative, and ne-normative monogenetic
basalts with both subduction and within-plate signatures in the CAVP. 相似文献
20.
Gonca Gen?alio?lu Ku?cu 《Bulletin of Volcanology》2012,74(1):303-304