Global scale evaluation of coastal fresh groundwater resources

This paper presents a simplified approach to assess the effects of global warming on global coastal groundwater resources over the next century based on the smallest but necessary number of elements such as rainfall, temperature, hydraulic conductivity of the aquifers, and population changes regarding the consumption of groundwater. The positive aspect in this approach is that there is availability of the above elements in the majority of the planet. Methodology includes a sharp interface concept model and simplified estimation of groundwater recharge using limited climate data. The evaluation shows that the future climate changes would decrease fresh groundwater resources in Central American, South American, South African and Australian regions whereas most of the areas in Asia, except South-East Asia. Combinations of fresh groundwater loss and global population are considered to state the vulnerability of future fresh groundwater supply. Vulnerability assessment shows that South Asia, Central America, North Africa and the Sahara, South Africa and the Middle East countries are highly vulnerable whereas, Northern Europe, Western part of South America, New Zealand and Japan are less vulnerable with respect to future fresh groundwater supply. Further, this paper highlights the necessity Integrated Coastal Management (ICM) practices in these vulnerable coastal regions to ensure the sustainable development in coastal regions.     

Polar wandering path for India during the Precambrian

Summary The recent radiometric dating on some Precambrian formations of India and the available paleomagnetic data have enhanced the possibility of deducing the Polar wander path for India during the remote past. The data indicate that India was in the northern hemisphere during the Precambrian times. This inference has also been substantiated by the paleoclimatic evidences.     

Glacial-interglacial changes in the surface water characteristics of the Andaman Sea: Evidence from stable isotopic ratios of planktonic foraminifera

Stable carbon and oxygen isotopic analyses of the planktonic foraminifera (Globigerinoides ruber) from a deep sea sediment core (GC-1) in the Andaman Sea show high glacial-to-Holocene δ¹⁸O amplitude of 2.1%o which is consistent with previously published records from this marginal basin and suggest increased salinity and/or decreased temperature in the glacial surface waters of this region. A pulse of¹⁸O enrichment during the last deglaciation can be attributed to a Younger Dryas cooling event and/or to a sudden decrease of fresh water influx from the Irrawady and Salween rivers into the Andaman Sea. High δ¹³C values observed during the isotopic stages 2 and 4 are probably due to the enhanced productivity during glacial times in the Andaman Sea.     

Accelerated expansion of the universe in a non-trivial extra-dimensional topology

The recent observational available data for an accelerated expansion state of the present universe, obtained from distant SNeIa gave strong support to the search of alternative cosmologies. Recently, there have been a number of different attempts to modify Einstein’s gravity to yield accelerated expansion at late times. Unfortunately, many of the theoretical models discussed in the literature are plagued with theoretical problems, in particular the singularity problem at the origin of time. In the present work we have analyzed a multidimensional spacetime Friedmann–Robertson–Walker (FRW) model with a decaying cosmological constant and a varying gravitational constant. Many interesting consequences are revealed, in particular the behavior of the scale factor and the shape of the universe in terms of the number of extra dimensions.     

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.     

Dynamics of energy sector and GHG emissions in Saudi Arabia

The energy sector is the main contributor to GHG emissions in Saudi Arabia. The tremendous growth of GHG emissions poses serious challenges for the Kingdom in terms of their reduction targets, and also the mitigation of the associated climate changes. The rising trend of population and urbanization affects the energy demand, which results in a faster rate of increase in GHG emissions. The major energy sector sources that contribute to GHG emissions include the electricity generation, road transport, desalination plants, petroleum refining, petrochemical, cement, iron and steel, and fertilizer industries. In recent years, the energy sector has become the major source, accounting for more than 90% of national CO₂ emissions. Although a substantial amount of research has been conducted on renewable energy resources, a sustainable shift from petroleum resources is yet to be achieved. Public awareness, access to energy-efficient technology, and the development and implementation of a legislative framework, energy pricing policies, and renewable and alternative energy policies are not mature enough to ensure a significant reduction in GHG emissions from the energy sector. An innovative and integrated solution that best serves the Kingdom's long-term needs and exploits potential indigenous, renewable, and alternative energy resources while maintaining its sustainable development stride is essential.

Policy relevance

The main contributor to GHG emissions in Saudi Arabia is the energy sector that accounts for more than 90% of the national CO₂ emissions. Tremendous growth of GHG emissions poses serious challenges for the Kingdom in their reduction and mitigating the associated climate changes. This study examines the changing patterns of different activities associated with energy sector, the pertinent challenges, and the opportunities that promise reduction of GHG emissions while providing national energy and economic security. The importance of achieving timely, sustained, and increasing reductions in GHG emissions means that a combination of policies may be needed. This study points to the long-term importance of making near- and medium-term policy choices on a well-informed, strategic basis. This analytical paper is expected to provide useful information to the national policy makers and other decision makers. It may also contribute to the GHG emission inventories and the climate change negotiations.     

Depositional Environments and Diagenesis of the Kuldhar and Keera Dome Carbonates (Late Bathonian–Early Callovian) of Western India

This paper describes 11 microfacies types in late Bathonian–Early Callovian carbonates of the Kuldhar Member of the Jaisalmer Formation (Rajasthan) and the Keera Golden Oolite Member of the Chari Formation (Kachchh Mainland) western India. The different microfacies associations reported in this study reflect an ideal shallowing upward sequence, representing a system of bioclastic bars developed on the lower ramp, evolving into an oolitic bar-to-bank system separating restricted lagoonal—from lower ramp environment. Four main types of cements, i.e. bladed, fibrous, syntaxial overgrowth and blocky cement (characterized in a few cases by ferroan calcite and anhydrite II) occur in these carbonates. The study also reveals that chemical compaction followed the two phases of early mechanical compaction that largely governed porosity of these limestones. However, micritization and neomorphism also contributed significantly in this respect. Diagenetic signatures in these carbonates suggest that marine phreatic and fresh water phreatic environments dominated, but deep burial diagenesis also played its role in shaping these rocks. The early and late diagenetic changes have been controlled by the depositional facies evolving in a basin riddled with rifting in an extensional tectonic regime forcing regional-scale sea level fluctuations.     

Malachite Green Adsorption onto Chitosan Coated Bentonite Beads: Isotherms,Kinetics and Mechanism

The removal of Malachite green (MG) from aqueous solutions by cross‐linked chitosan coated bentonite (CCB) beads was investigated and the CCB beads were characterized by Fourier Transform Infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and X‐ray diffraction (XRD) analysis. Solubility and swelling tests were performed in order to determine the stability of the CCB beads in acidic solution, basic solution and distilled water. The amount of MG adsorbed was shown to be influenced by the initial pH of the solution, contact time and the initial MG concentration. A kinetic study indicated that a pseudo‐second‐order model agreed well with the experimental data. From the Langmuir isotherm model, the maximum adsorption capacity of MG was found to be 435.0 mg g^–1. Desorption tests were carried out at different concentrations of EDTA, H₂SO₄ and NaOH. However, all desorbing solutions showed zero recovery of MG at all concentrations.