Search

The current research work represents the first calcareous nannofossil biostratigraphic record of the upper Eocene Rashrashiyah Formation in northern Saudi Arabia. The Rashrashiyah Formation is an Eocene carbonate sedimentary unit, exposed adjacent to the Jordanian border, and yielded rich and diverse nannofossil assemblages. The Rashrashiyah Formation overlies the Paleogene rocks of the Umm Wu'al Formation and is unconformably topped by the Neogene (Miocene) Sirhan Formation. Our nannofossil biostratigraphic data recognized 44 species belonging to 21 genera. These taxa indicate a Priabonian age based on the presence of Chiasmolithus oamaruensis, and the recognition of bioevents in concordance with the global Priabonian zonations. Three comparable major zones and zonal boundaries (CP14b/CP15, NP18, and CNE17) were recognized in the study section indicative of a late Eocene age. The Base common (Bc) of Reticulofenestra erbae was detected at the same level as the top of Chiasmolithus grandis, supporting the bioevent reliability in the Tethys realm. A single and more isolated occurrence of Isthmolithus recurvus was observed within Zones CP15 and NP18 at the maximum increase abundance of R. erbae. Our calcareous nannofossil biostratigraphy from the Rashrashiyah Formation has coincided with the assignment for units 2 and 3 of the Wadi Esh-Shallalah Formation in Qa' Faydat ad Dahikiya in the eastern desert Jordan. [ABSTRACT FROM AUTHOR]

Groundwater quality in the Basin of Dhamar (Yemen) has been studied using geographic information system (GIS), principal component analysis (PCA) and correlation technique. A geographic information system is a tool for mapping and analyzing spatial data and is also used to retrieve groundwater quality information. For this study 26 wells were selected, for each well thirteen physicochemical parameters were analyzed including electrical conductivity, Calcium (Ca2+), Magnesium (Mg2+), Sodium (Na+), potassium (K+), bicarbonate (HCO3-), Chloride (Cl-), Sulphate (SO42-), Nitrate (NO3-), Iron (Fe2+), Fluoride (F-) and Total Hardness (TH). The collected groundwater was evaluated for its suitability for both drinking and irrigation purposes. Correlation and PCA have been utilized to analyze the parameters. Cartographic maps of the study area have been generated using multivariate statistical tools and GIS approach Inverse Distance Weighting (IDW) for all the above parameters. The created maps can be used to visualize, analyze, and understand the relationship among all locations. Most of the wells are found to be within the permissible limit except one well and this is due to the anthropogenic pollution received by human activities. Correlation and principal component analysis can help in selecting the most significant parameters to determine the status of water quality. The tools available in the GIS environment supported the study in the integration of data with very different data structures, i..e. point, 2D and 3D, towards spatial modeling of processes relevant to the assessment of groundwater resources. [ABSTRACT FROM AUTHOR]

The objective of this study is to evaluate economically the passive solar heating system. Data collected from tomato greenhouses in the Agriculture Research Center of Northern Greece was analyzed. For Comparison, two other conventional heating systems were used: the traditional anti-frost system and the diesel-fired furnace system. Models have been constructed to assess each heating method and several approaches of appraisal such as net present value, internal rate of return, benefit/cost ratio and payback period were measured in order to fulfill the assessment. The importance of the passive solar system was revealed not only as an energy-saving method but also as a significant contributor to farmer’s income and an appropriate system avoiding the risk of high initial investment, which is generally associated with unconventional systems. Meanwhile, it was indicated that the diesel-fired furnace system is ineffective compared to the passive solar system, this ineffectiveness is particularly due to its high fuel consumption and relatively high initial investment. Finally, sensitivity analysis highlighted the importance of the product price in affecting benefits and indicating that income will increase dramatically with earlier production. [ABSTRACT FROM AUTHOR]

Remote Sensing applications in agricultural practices are comprehensively reliable and cover a multidisciplinary fundamental interest on a local as well as on a regional level. Significantly, vegetation indices are foremost essential remote sensing applications in agricultural activities related to vegetation and/or water, particularly in an arid environment. Adequate water resources management plans are based on better fulfilment of water demand and supply equation. In arid environments, this equation is barely achieved due to water resources limitations. Remote sensing techniques improve the water resources management schemes using five different water radiometric indices of Sentinel-2. Each of them plays a specific role in the quantification of soil/plant water content based on the interpretation of map surface water features and monitors the dynamic of surface water. The study area is located within the main agricultural region of Wadi As-Sirhan, Saudi Arabia. The area is characterized by flourishing agricultural activities. Remote Sensing data acquired by Sentinel-2 proved to be statistically sufficient to estimate soil water content in two different climatic conditions. Statistically, winter estimated indices are a better fit than summer indices. MNDWI and NDWI-2 were best to fit winter soil water content estimations. Meanwhile, RMSE shows no differences between NDWI and NDTI in both climatic conditions. [ABSTRACT FROM AUTHOR]

Decontamination of heavy metal polluted soil and water by plants is called phytoremediation. Succulent plant species such as Aloe vera (L.) are considered for the current study to investigate their ability to accumulate heavy metals and their uptake rate of different heavy metals are tested. This study aimed to measure the concentration of toxic heavy metals (As, Cd, Cr, Cu, Pb, Hg, and Ni) in arid contaminated soils of Saudi Arabia. The soil was contaminated with 1500 ppm of each element. During a year of the experiment, 4 samples were taken on a trimester basis. All samples were digested to measure heavy metal content in soil and plant. Metal Transfer Factor (MTF) and Translocation Factor (TF) were calculated from the examined data. This study showed that the A. vera has the ability to decontaminate heavy metals from polluted soil. The greatest accumulation was detected from As but the accumulation was declined after 9 months. Hg accumulation showed no significant results of heavy metal uptake by A. vera. The greatest MTF was of Cd elements and counted for 1.3404 and the lowest was of Cr and counted for 0.1292. Cd TF was the maximum (2.8538) but Pb TF was the minimum (1.2191). [ABSTRACT FROM AUTHOR]

Phrygana is a widespread vegetat type in the eastern Mediterranean, mainly represented by Sarcopoteriwn spinosum dominated formations in the Aegean islands and Crete. The effects of overgrazing and frequent burnings on phrygana are relatively known by scientists, but limited attention has been paid to the functioning of these communities when grazing and fires are suppressed. The aim of this study is to investigate post-fire vegetation and fuel dynamics in an ungrazed S. spinosium dominated phrygana in northwestern Crete. Fuel was first analyzed according to shrub, herb, litter, and total load; then live and dead materials; and finally, 0-0.5 cm and 0.6-2.5 cm of leaf diameter classes. Vegetation was analyzed based on cover and life form composition and dynamics. Also, species richness, diversity, and dynamics were investigated. One-way ANOVA was used to test for fuel and vegetation differences among sites, and Shannon-Wiener and Equitability indices were used to assess both diversity and evenness. Results showed a rapid reestablishment of both the vegetation (cover, life form, species richness and diversity) and fuel, as early as the 3rd and the 6th post-fire year, respectively. Fuel and vegetation were tremendously dominated by unpalatable and highly flammable dwarf shrubs, which smothered herbaceous plants. Species diversity was relatively low, indicating that few species crushingly structured the community by their high cover, while the remaining species were poorly abundant. The implications of the results in the context of a rational management planning of phryganic ecosystems are discussed. [ABSTRACT FROM AUTHOR]

This study aimed at determining the transpiration characters of Juniperus macrocarpa in a close to 40-year-old even-aged stand categorized into three classes based on canopy size, over a two-year period (2011-2012). The site is located in Palaiochora, 77 km south of Chania, on the southwest coast of Crete. Sap flow techniques (Granier-type) were used to determine water use. Annual trends in sap flow were generally bell-shaped, and varying significantly between seasons and canopy classes. Winter sap flow was minimal but trees were active when temperatures were above freezing point and trees depended on deep water (below 60 cm) for transpiration. Rates increased from 1.46 Ld-1 in winter to 3.32 Ld-1 in the spring, irrespective of tree canopy class, because of improvement in weather conditions. Maximum transpiration rates were observed during the growing season with an average of 134.42 Ld-1 for dominant trees and 8.68 Ld-1 for suppressed ones. The daily variations in photosynthetically active radiation, vapor pressure deficit, air temperature, and surface soil water were the principal drivers for transpiration during the growing season. The findings have shown that climate in Crete does not limit the expansion of J. macrocarpa and that this expansion will have potentially significant impacts on the ecohydrology of the system. [ABSTRACT FROM AUTHOR]