Germination and growth of six plant species on contaminated soil with spent oil

Effects of contaminated soil with spent oil on germination, above ground height and biomass of six herbaceous plant species were investigated by conducting a general phytotoxicity test and growth inhibition assessment. Six local plant species were used in order to investigate plant’s ability to germinate and survive in a gradient of contaminated soil with spent oil. The species selected for this experiment include one species of Fabaceae (Medicago truncatular), four species of Gramineae (Bromous mermis, Secal seral, Triticum sativa and A gropyron deserterum) and one species of Linaceae (Linum ussitasimum). Inhibitory effect of contaminated soil on germination, height of young seedling and dry weight were measured. In this study an artificial soil with a light texture included 85% sand, 10% silt and 5% clay was used. The exposure to the contaminated soil carried out using four consecutive concentrations (25, 50, 75, 100 g/kg). Results obtained from the current investigation indicate that all species perform dose-dependent responses to the contaminated soils. Reduction in germination, above ground height and biomass for all species were significantly (P < 0.05) different when compared to their controls, however, Medicago truncatular performed the highest and Linum ussitatisimum the lowest inhibitory effect for germination, above ground height and dry weight of seedling.     

Time-domain two-dimensional site response analysis of non-homogeneous topographic structures by a hybrid BE/FE method

In this paper, an advanced formulation of the time-domain, two-dimensional hybrid finite element–boundary element method (FEM/BEM) is presented, and applied to carry out site response analysis of homogeneous and non-homogeneous topographic structures subjected to incident in-plane motions. Seismic responses of half-plane, horizontally layered site, alluvial valley and ridge sections subjected to incident P and SV waves are analyzed in order to demonstrate the applicability and efficiency of the presented method. The numerical results show that hybrid BE/FE methods require smaller time steps than those needed by BEM schemes. They also show that in case of surface irregularities with height to half-width ratio of up to one, the topography effect could be noticeable, if incident waves have wavelengths of less than approximately eight times the width.     

Response of a 2-story test-bed structure for the seismic evaluation of nonstructural systems

A full-scale, two-story, two-by-one bay, steel braced-frame was subjected to a number of unidirectional ground motions using three shake tables at the UNR-NEES site. The test-bed frame was designed to study the seismic performance of nonstructural systems including steel-framed gypsum partition walls, suspended ceilings and fire sprinkler systems. The frame can be configured to perform as an elastic or inelastic system to generate large floor accelerations or large inter story drift, respectively. In this study, the dynamic performance of the linear and nonlinear test-beds was comprehensively studied. The seismic performance of nonstructural systems installed in the linear and nonlinear test-beds were assessed during extreme excitations. In addition, the dynamic interactions of the test-bed and installed nonstructural systems are investigated.     

Local Ionospheric Modeling Using the Localized Global Ionospheric Map and Terrestrial GPS

global ionosphere maps are generated on a daily basis at CODE using data from about 200 GPS/GLONASS sites of the IGS and other institutions. The vertical total electron content is modeled in a solargeomagnetic reference frame using a spherical harmonics expansion up to degree and order 15. The spherical Slepian basis is a set of bandlimited functions which have the majority of their energy concentrated by optimization inside an arbitrarily defined region, yet remain orthogonal within the spatial region of interest. Hence, they are suitable for decomposing the spherical harmonic models into the portions that have significant strength only in the selected areas. In this study, the converted spherical harmonics to the Slepian bases were updated by the terrestrial GPS observations by use of the least-squares estimation with weighted parameters for local ionospheric modeling. Validations show that the approach adopted in this study is highly capable of yielding reliable results.     

The effect of mineralization on the ratio of normal to tangential compliance of fractures

The effect of a fracture on the propagation of seismic waves can be represented in terms of the normal compliance B_N and tangential compliance B_T of the fracture. If   B_N / B_T = 1  for all fractures, the effective elastic stiffness tensor of an isotropic background containing an arbitrary orientation distribution of fractures is orthotropic (i.e., has three orthogonal planes of mirror symmetry) in the long-wave limit. However, deviations from orthotropy may occur if   B_N / B_T   differs significantly from unity and this can cause the principal axes of the P -wave NMO ellipse and of the variation in the PP -reflection amplitude as a function of azimuth, to deviate from the fast and slow polarization direction of a vertically propagating S -wave. Simple models of a fracture in terms of a planar distribution of cracks suggest that   B_N / B_T ≈ 1  for dry fractures. However, naturally occurring fractures often exhibit mineralization in the form of bridges between opposing faces of the fracture. The presence of such bridges leads to significant departures of   B_N / B_T   from unity.     

Determination of the optimum sealing method for Azad pumped storage dam considering seepage analysis

Seepage analysis of the upper reservoir of the Kurdistan Azad pumped storage dam with a volume of 3.8E+5 m³ is a key step for selection of the optimized sealing method. More than 60% of the Lugeon test results show very permeable behavior for the pit and abutments of the reservoir. In this study, regarding the permeability value of the reservoir abutments and pit obtained by means of Lugeon tests, seepage rate was computed using various analytical and numerical methods. Reservoir total seepage discharge was computed in steady-state regime by means of analytical and numerical methods (SEEP/W finite element software) as 1.14E+05 and 1.15E+05 m³/day, respectively. Distinct element method (UDEC software) showed variable behavior for the seepage flow. In the reservoir initial impounding stages, the amount of seepage was very high (1.70E+06 m³/day). Then, the seepage rate decreased gradually and reached to a constant value (1.12E+05 m³/day). For the reservoir 3D modeling, Seep3D commercial software was used and has shown water seepage discharge of about 1.18E+05 m³/day, means 3% of total reservoir volume. Based on the above-mentioned results and regarding behavior of seepage in the initial impounding stages, sealing element is necessary to prevent from seepage phenomenon. Clay blanket, concrete lining, asphaltic concrete, and geosynthetic are the proposed methods in a large water reservoir. After a feasibility study on various sealing methods, geomembrane was suggested as the best sealing method with the reasonable implementation cost.     

Causes and consequences of recent floods in the Golestan catchments and Caspian Sea regions of Iran

In August 2001, the worst flash flooding event of the Caspian Sea regions in over two centuries claimed over 300 lives after a weekend of heavy rainfall and brought about a devastating disaster in the Mother-Soo catchment, province of Golestan, Iran. As a result of this event, a series of site investigation were carried out to identify the pertinent factors that led to a flood of this magnitude. This paper identifies the fundamental causes of the frequent floods and debris flow occurrence in the area prone to flooding and analyzes the main runoff mechanism of these events. The maximum observed 24-h rainfall depths and maximum peak discharges at the existing gauges were compared with the depths of rainfall and the peak values corresponding to the August 2001 flood respectively. For the majority of the rain gauges, the rainfall depth exceeded those of historical recorded events. In Golestan dam, an increase of 7.5 times the maximum value observed in the past 20 years was noted. The flood height was 10–15 m while passing through the middle subcatchment area of Golestan National Park. The preliminary evaluation indicates the existence of bare soil in the catchment, movable material, steep slopes, high rainfall intensity, deterioration of pasture and forest land, and inappropriate agriculture and development practices as well as climate change were the main factors for the occurrence and the extent of the August 2001 disaster. Finally, due to the likelihood of flooding and debris flow events in future, some countermeasures are proposed.     

Metamorphism and deformation of golpayegan metapelitic rocks, Sanandaj-Sirjan Zone, Iran

The metapelitic schists of the Golpayegan region can be divided into four groups based on their mineral assemblages: (1) garnet-chloritoid schists, (2) garnet schists, (3) garnet-staurolite schists, and (4) staurolite-kyanite schists. Paleozoic pelagic shales experienced progressive metamorphism and polymetamorphism from greenschist to amphibolite facies along the kyanite geotherm. Mylonitic granites are concentrated in the central part of the region more than in other areas, and formed during the dynamic metamorphic phase by activity on the NW-SE striking Varzaneh and Sfajerd faults. The presence of chloritoid in the metapelites demonstrates low-grade metamorphism in the greenschist facies. The textural and chemical zoning of garnets shows three stages of growth and syntectonic formation. With ongoing metamorphism, staurolite appeared, and the rocks reached amphibolite facies, but the degree of metamorphism did not increase past the kyanite zone. Thus, metamorphism of the pelitic sediments occurred at greenschist to lower amphibolite facies. Thermodynamic studies of these rocks indicate that the metapelites in the north Golpayegan region formed at 511?C618°C and 0.24?C4.1 kbar.     

Origin of brine in the Kangan gasfield: isotopic and hydrogeochemical approaches

The Kangan Permo-Triassic brine aquifer and the overlying gas reservoir in the southern Iran are located in Kangan and Dalan Formations, consisting dominantly of limestone, dolomite, and to a lesser extent, shale and anhydrite. The gasfield, 2,900 m in depth and is exploited by 36 wells, some of which produce high salinity water. The produced water gradually changed from fresh to saline, causing severe corrosion in the pipelines and well head facilities. The present research aims to identify the origin of this saline water (brine), as a vital step to manage saline water issues. The major and minor ions, as well as δ²H, δ¹⁸O and δ³⁷Cl isotopes were measured in the Kangan aquifer water and/or the saline produced waters. The potential processes causing salinity can be halite dissolution, membrane filtration, and evaporation of water. The potential sources of water may be meteoric, present or paleo-seawater. The Na/Cl and I/Cl ratios versus Cl^? concentration preclude halite dissolution. Concentrations of Cl, Na, and total dissolved solid were compared with Br concentration, indicating that the evaporated ancient seawater trapped in the structure is the cause of salinization. δ¹⁸O isotope enrichment in the Kangan aquifer water is due to both seawater evaporation and interaction with carbonate rocks. The δ³⁷Cl isotope content also supports the idea of evaporated ancient seawater as the origin of salinity. Membrane filtration is rejected as a possible source of salinity based on the hydrochemistry data, the δ¹⁸O value, and incapability of this process to dramatically enhance salinity up to the observed value of 330,000 mg/L. The overlaying impermeable formations, high pressure in the gas reservoir, and the presence of a cap rock above the Kangan gasfield, all prevent the downward flow of meteoric and Persian Gulf waters into the Kangan aquifer. The evaporated ancient seawater is autochthonous, because the Kangan brine aquifer was formed by entrapment of brine seawater during the deposition of carbonates, gypsum, and minor clastic rocks in a lagoon and sabkha environment. The reliability of determining the source of salinity in a deep complicated inaccessible high-pressure aquifer can be improved by combining various methods of hydrochemistry, isotope, hydrodynamics, hydrogeology and geological settings.