Biochar effects on metal bioaccumulation and arsenic speciation in alfalfa (<Emphasis Type="Italic">Medicago sativa L</Emphasis>.) grown in contaminated soil

Mining and geogenic activities can lead to elevated concentrations of potentially toxic elements in soil. Biochar amendment to soil is a cost-effective technology and environmentally friendly approach to control soil pollution, improve phytoremediation and mitigate health risks due to agricultural products. Greenhouse pot experiments were conducted to investigate the effects of rice husk biochar on alfalfa biomass, metal bioaccumulation and arsenic speciation. Results indicated that rice husk biochar amendments to contaminated soil increased plants biomass by improving soil fertility and available nutrients. Biochar also increased soil cation change capacity, dissolved organic carbon, while decreased available concentrations of potentially toxic elements (except for arsenic). The accumulation of nickel, lead, cadmium and zinc (except for chromium and arsenic) significantly (P ≤ 0.05) decreased as compared with unamended control plants. In addition, increases were observed for inorganic arsenite and arsenate. Current findings demonstrate that rice husk biochar can be used as a beneficial amendment for contaminated soil. However, further field experiments are needed to validate its long-term effectiveness where environmental factors are diverse and complex.     

<Superscript>1</Superscript>H NMR-based serum metabolic profiling of <Emphasis Type="Italic">Carassius auratus gibelio</Emphasis> under the toxicity of Pb<Superscript>2+</Superscript> and Cd<Superscript>2+</Superscript>

Lead and cadmium are the two widely recognized toxic metals, with known ecological risk to freshwater fish in contaminated ecosystems. However, their effect at environmentally realistic level in a mixture has been rarely investigated. In the present study, serum metabolic responses of Crucian carp exposed to Pb (30 µgL^?1), Cd (100 µgL^?1) and Pb+Cd (30 + 100 µgL^?1) for 21 days were investigated by ¹H NMR-based metabolomics. The metabolic responses were compared to control by multivariate techniques (PCA, PLS-DA and OPLS-DA), and metabolites that significantly contributed to the variation were identified. Metal dependent metabolic responses revealed a decline of alanine, lysine and tyrosine in Pb exposed fish, indicating changes in neurotransmitters, and amino acid metabolism, while fish exposed to Cd showed significant decrease in lysine, isoleucine, leucine, alanine and increase in 3-hydroxybutyrate, acetone, lactate, choline, inosine, guanosine and threonine. The coexposure of Pb and Cd had additive effect on metabolic profile with increase in pyruvate, guanosine and inosine. The overall metabolic changes due to Pb and Cd were characterized by disturbed energy metabolism, impaired osmotic regulation and a shift from aerobic to anaerobic respiration. Moreover, ¹H NMR-based metabolomics was proved to be a powerful tool in elucidating the toxic effects of environmental pollutants and underlying mechanism.     

Numerical modeling of the geomechanical behavior of Ghawar Arab-D carbonate petroleum reservoir undergoing CO<Subscript>2</Subscript> injection

Sedimentary porous rocks can be used for long-term subsurface containment of CO₂. Before injecting CO₂ to sedimentary reservoirs, it is necessary to perform stability analysis of the reservoir and to estimate the maximum sustainable pore fluid pressures. In order to avoid the reservoir damage during the CO₂ injection, the effective stresses in the reservoir should be evaluated. In this paper, numerical modeling techniques are used for the evaluation of stresses and deformations in a naturally fractured carbonate sedimentary reservoir. The developed numerical modeling scheme couples the behavior of the CO₂ injection and the change in the geomechanical behavior of the sedimentary carbonate reservoir for a case study from Saudi Arabia. The present investigation extends the previous studies by considering the sorption-based deformation during the injection of the compressed CO₂ fluid into the Arab-D naturally fractured carbonate reservoir. The change in permeability during the injection of CO₂ is evaluated. The adopted CO₂ injection scenario was shown to be within the safe maximum occupancy, and that the increase in the pore pressure does not result in the reservoir failure.     

Bela oceanic lithosphere assemblage and its relation to the Réunion hotspot

The Bela ophiolite of Pakistan contains a complete ophiolite-accretionary wedge-trench sequence emplaced onto the Indian continental margin during the northward drift of India-Seychelles over the active Réunion hotspot. A structurally higher ophiolite overlies an accretionary prism, which is thrust over a foreland basin. Shear-sense determinations in peridotite mylonites in the ophiolite footwall and imbrication structures in the underlying accretionary wedge indicate an ESE emplacement. Sedimentary rocks in the accretionary wedge indicate Aptian-Albian pillow lavas, initially deep water conditions, and increasing influence from the continent until the Maastrichtian. The ophiolite emplacement was predated and accompanied by Fe-tholeiitic and alkaline magmatism related to the Réunion hotspot and continuous incorporation of trench sediments into the accretionary wedge. ³⁹Ar/⁴⁰Ar dating shows that the ophiolite formed around 70 Ma. Intraoceanic subduction initiated between 70 and 65 Ma, obduction onto the Indian passive margin occurred during the formation of the Deccan traps at ≈ 66 Ma, and final thrusting onto the continental margin ended in the early Eocene (≈ 50 Ma). The ophiolite emplacement occurred during the counterclockwise separation of Madagascar and India-Seychelles which caused shortening and consumption of oceanic lithosphere between the African-Arabian and the Indian-Seychelles plates.     

Discovery of antler from a new site in the Pinjor Formation (Pleistocene) of Pakistan

Partially complete right antler from the Pinjor Formation (Pleistocene) of the Upper Siwalik Subgroup is identified, described and its phylogenetic relationship is discussed. The fossil antler is compared with other known fossil records of family Cervidae as well as with the extant species, on the basis of which it can be attributed to Axis punjabiensis. This species has not been reported previously from this fossil site.     

http://www.sciencedirect.com/science/article/pii/S1674987111001289

The disastrous M_w 9.3(seismic moment 1.0×10³⁰ dyn/cm) earthquake that struck northwest Sumatra on 26 December 2004 and triggered～30 m high tsunami has rejuvenated the quest for identifying the forcing behind subduction related earthquakes around the world.Studies reveal that the strongest part（elastic core） of the oceanic lithosphere lie between 20 and 60 km depth beneath the upper （～7 km thick） crustal layer,and compressive stress of GPa order is required to fail the rock-layers within the core zone.Here we present evidences in favor of an intraplate origin of mega-earthquakes right within the strong core part（at the interface of semi-brittle and brittle zone）,and propose an alternate model exploring the flexing zone of the descending lithosphere as the nodal area for major stress accumulation. We believe that at high confining pressure and elevated temperature,unidirectional cyclic compressive stress loading in the flexing zone results in an increase of material yield strength through strain hardening, which transforms the rheology of the layer from semi-brittle to near-brittle state.The increased compressive stress field coupled with upward migration of the neutral surface（of zero stress fields） under noncoaxial deformation triggers shear crack.The growth of the shear crack is initially confined in the near-brittle domain,and propagates later through the more brittle crustal part of the descending oceanic lithosphere in the form of cataclastic failure.     

Seismogenic sources in the Bay of Bengal vis-à-vis potential for tsunami generation and its impact in the northern Bay of Bengal coast

Geodynamic status, seismo-tectonic environment, and geophysical signatures of the Bay of Bengal do not support the occurrence of seismogenic tsunami. Since thrust fault and its intensity and magnitude of rupture are the key tectonic elements of tsunamigenic seismic sources, the study reveals that such characteristics of fault-rupture and seismic sources do not occur in most of the Bay of Bengal except a small segment in the Andaman–Nicobar subduction zone. The inferred segment of the Andaman–Nicobar subduction zone is considered for generating a model of the deformation field arising from fluid-driven source. The model suggests local tsunami with insignificant inundation potential along the coast of northern Bay of Bengal. The bathymetric profile and the sea floor configuration of the northern Bay of Bengal play an important role in flattening the waveform through defocusing process. The direction of motion of the Indian plate makes an angle of about 30° with the direction of the opening of Andaman Sea. The opening of Andaman Sea and the direction of plate motion of the Indian plate results in the formation of Andaman trench where the subducting plate dives more obliquely than that in the Sunda trench in the south. The oblique subduction reduces significantly the possibilities of dominant thrust faulting in the Andaman subduction zone. Further, north of Andaman subduction in the Bengal–Arakan coast, there is no active subduction. On the otherhand, much greater volume of sediments (in excess of 20 km) in the Bengal–Arakan segment reduces the possibilities of mega rupture of the ocean floor. The water depth (≈1,000 m) along most of the northern Bay of Bengal plate margin is not optimum for any significant tsunami generation. Hence, very weak possibility of any significant tsunami is suggested that based on the interpretation of geodynamic status, seismo-tectonic environment, and geophysical signatures of the Andaman subduction zone and the Bengal–Arakan coast.     

Cervid remains from the middle Siwaliks of Hasnot (Late Miocene), Pakistan

The late Miocene-early Pliocene fossil deposits of Hasnot in northern Pakistan have yielded a very rich vertebrate fauna. In this paper we describe the remains of Cervidae from six of these localities. By dental remains, at least four species of cervids are documented. These remains significantly widen the time distribution of the cervids and draw back the first appearance of cervids in the Dhok Pathan Formation of the Siwaliks. The data indicate a diverse set of coexisting ungulates in the area, subsisting within a mosaic of habitats.