Confirming Ground Geophysical Survey for Mineralization in Al Bayda Area,Yemen

1IntroductionThe study area lies in the northern part of Al Jarra village in Di Naim-Al Bayda District (Fig. 1). The area under investigation is characterized by rugged topography and generally covered by base-ment rocks. The northern part of the study ar…     

Effects of land use and climate variability on the main stream of the Songhua River Basin,Northeast China

ABSTRACT

In this study, three representative concentration pathways (RCPs) and 15 general circulation models of the Coupled Model Intercomparison Project Phase 5 were used to assess the behaviour of precipitation (P) and surface air temperature (SAT) over part of the Songhua River Basin. The Water Evaluation and Planning (WEAP) model linked with SAT and P was used for monthly simulation of streamflow to assess the influence of land use/land cover and climate change on the streamflow. The results suggest that, under RCP2.6, RCP4.5 and RCP8.5, the SAT over the study area may increase in the 21st century by 1.12, 2.44 and 5.82°C, respectively. Moreover, by the middle of the 21st century, streamflow in the basin may have decreased by 19%. The decrease in streamflow may be due to changed land use conditions and water withdrawal, having critical implications for management and future planning of water resources in the basin.     

Facies Analysis, Sequence Stratigraphy and Diagenetic Studies of the Jurassic Carbonates of the Kohat Basin, Northwest Pakistan: Reservoir Implications

The present study deals with the depositional facies, diagenetic processes and sequence stratigraphy of the shallow marine carbonates of the Samana Suk Formation, Kohat Basin, in order to elucidate its reservoir quality. The Samana Suk Formation consists of thin to thick-bedded, oolitic, bioclastic, dolomitic and fractured limestone. Based on the integration of outcrop, petrographic and biofacies analyses, the unit is thought to have been deposited on a gentle homoclinal ramp in peritidal, lagoonal and carbonate shoal settings. Frequent variations in microfacies based sea-level curve have revealed seven Transgressive Systems Tracts (TSTs) and six Regressive Systems Tracts (RSTs). The unit has undergone various stages of diagenetic processes, including mechanical and chemical compaction, cementation, micritization, dissolution and dolomitization. The petrographic analyses show the evolution of porosity in various depositional and diagenetic phases. The fenestral porosity was mainly developed in peritidal carbonates during deposition, while the burial dissolution and diagenetic dolomitization have greatly enhanced the reservoir potential of the rock unit, as is further confirmed by the plug porosity and permeability analyses. The porosities and permeabilities were higher in shoal facies deposited in TSTs, as compared to lagoonal and peritidal facies, except for the dolomite in mudstone, deposited during RSTs. Hence good, moderate and poor reservoir potential is suggested for shoal, lagoonal and peritidal facies, respectively.     

Rock Physics Modeling and Reservoir Characterization to Estimate Hydrocarbon Zone of Cretaceous and Paleocene Strata and Subsurface Stratigraphic Correlation of Sulaiman Fold Belt to Sulaiman Depression

Doklady Earth Sciences - The research work involves rock physics modeling and reservoir characterization of Suliman fold belt to sulamain fold depression. This area is a brighter zone for...     

DNA adducts in hematopoietic tissues and blood of the mummichog (Fundulus heteroclitus) from a creosote-contaminated site in the Elizabeth River, Virginia.

Hydrophobic DNA adducts were examined in liver, anterior kidney, spleen, and blood of tumor-prone mummichog (Fundulus heterclitus) from the creosote-contaminated Atlantic Wood (AW) site (Elizabeth River, Virginia). DNA adducts eluted in a diagonal radioactive zone, characteristic of polycyclic aromatic hydrocarbon exposure, in all examined tissues of AW fish. Mummichog demonstrated significantly higher levels of DNA adducts in spleen (394 +/- 109 nmol adducts/mol nucleotides) than in liver (201 +/- 77 nmol adducts/mol nucleotides) or anterior kidney (211 +/- 68 nmol adducts/mol nucleotides; P = 0.036). The levels of DNA adducts in the pooled blood (pool of four) were 142 nmol adducts/mol nucleotides. DNA adducts were not detected in the liver, anterior kidney, spleen and blood of fish collected from the reference site (< 2 nmol adducts/mol nucleotides). The high levels of DNA adducts detected in tissues of AW mummichog may be linked to the increased cancer incidence and immunosuppression in this population.     

Steered migration in hard rock environments

Hard rock seismic exploration normally has to deal with rather complex geological environments. These types of environments are usually characterized by a large number of local heterogeneity (e.g., faults, fracture zones, and steeply dipping interfaces). The seismic data from such environments often have a poor signal‐to‐noise ratio because of the complexity of hard rock geology. To be able to obtain reliable images of subsurface structures in such geological conditions, processing algorithms that are capable of handling seismic data with a low signal‐to‐noise ratio are required for a reflection seismic exploration. In this paper, we describe a modification of the 3D Kirchhoff post‐stack migration algorithm that utilizes coherency attributes obtained by the diffraction imaging algorithm in 3D to steer the main Kirchhoff summation. The application to a 3D synthetic model shows the stability of the presented steered migration to the presence of high level of the random noise. A test on the 3D seismic volume, acquired on a mine site located in Western Australia, reveals the capability of the approach to image steep and sharp objects such as fracture and fault zones and lateral heterogeneity.     

Group velocity dispersion analysis in northern Peninsular Malaysia

The crustal structure beneath three seismic stations over Malaysia has been investigated with the application of the group velocity dispersion analysis of the northern Sumatra earthquake data which occurred on 06 April 2010. Eighteen crustal layer models are constructed to assess the structure. Group velocity dispersions have been computed for the recorded earthquake data using a graphical method and modified Haskell matrix method for the models. Both dispersions have been presented for the interpretation of crustal layers. Findings have shown four major crustal layers having thicknesses of 2.5–4.0, 2.0–5.5, 5.0–8.0, and 8.5–9.0 km, while in Terengganu, it has shown three layers. Density, shear, and compressional wave velocities used in models have suggested that the crustal structure of the northern part of Peninsular Malaysia is crystalline. Major crustal minerals are of quartz, plagioclase, and mica. Most layers seem to have upward directions toward Perak from Kedah and Terengganu.     

Is correlation dimension a reliable proxy for the number of dominant influencing variables for modeling risk of arsenic contamination in groundwater?

The correlation dimension (CD) of a time series provides information on the number of dominant variables present in the evolution of the underlying system dynamics. In this study, we explore, using logistic regression (LR), possible physical connections between the CD and the mathematical modeling of risk of arsenic contamination in groundwater. Our database comprises a large-scale arsenic survey conducted in Bangladesh. Following the recommendation by Hossain and Sivakumar (Stoch Environ Res Risk Assess 20(1–2):66–76, 2006), who reported CD values ranging from 8 to 11 for this database, 11 variables are considered herein as indicators of the aquifer’s geochemical regime with potential influence on the arsenic concentration in groundwater. A total of 2,048 possible combinations of influencing variables are considered as candidate LR risk models to delineate the impact of the number of variables on the prediction accuracy of the model. We find that the uncertainty associated with prediction of wells as safe and unsafe by LR risk model declines systematically as the total number of influencing variables increases from 7 to 11. The sensitivity of the mean predictive performance also increases noticeably for this range. The consistent reduction in predictive uncertainty coupled with the increased sensitivity of the mean predictive behavior within the universal sample space exemplify the ability of CD to function as a proxy for the number of dominant influencing variables. Such a rapid proxy, based on non-linear dynamic concepts, appears to have considerable merit for application in current management strategies on arsenic contamination in developing countries, where both time and resources are very limited.     

Interactive effects of cadmium and benzo[a]pyrene on metallothionein induction in mummichog (Fundulus heteroclitus).

Previous experiments demonstrated that exposure of mummichog to cadmium (Cd) in combination with benzo[a]pyrene (BaP) caused a higher mortality than would be expected from simple additive effects. Experiments are described here that investigated whether BaP exposure inhibits the induction of metallothionein (MT), a major detoxifying protein for Cd, or if reactive BaP metabolites compete with Cd for binding sites on MT. Fish were injected with or without BaP (18 mg/kg) in combination with a low (1 mg/kg) or high (3.2 mg/kg) dose of Cd, and in one treatment BP was dosed 4 days after Cd. The results showed a rapid induction of MT to 1.5 mg/g wet weight liver, 1 day after injecting the low Cd dose. Simultaneous BaP exposure significantly delayed the induction of MT, for both low and high Cd doses, and BaP temporarily lowered the induced MT concentration when dosed 4 days after induction by Cd. To test if binding of BaP metabolites to MT reduces the detoxification potential for Cd, microsomes of CYP1A-induced fish were incubated with MT and radiolabeled BaP. Active metabolism of BaP was observed by high-performance liquid chromatography analysis, but no association of BaP metabolites with MT was found. Neither could this be demonstrated in vivo, in liver MT isolated from mummichog dosed with 3H-BaP and Cd. These results suggest that increased toxicity of Cd in combination with BaP exposure is likely to be caused by inhibited MT synthesis, rather than by interference of BaP metabolites with Cd binding on MT.