Heavy metal pollution and soil magnetic susceptibility in urban soil of Beni Mellal City (Morocco)

The assessment of anthropogenic impact in the urban environment can be evaluated according to heavy metal contents of soils such as Pb, Cu, Zn, Cd and Fe. These elements have more affinity to establish metallic bond with ferrous material leading to enhancement of soil magnetic susceptibility. The objective of this study was to undertake joint magnetic and geochemical investigations of road-side urban soil materials to address the environmental pollution of Beni Mellal city that has been subjected to environmental stress, due to population overpressure and related urbanization. Twenty three soils magnetic susceptibility profiles were made along 5 km peripheral national road (N8) in Beni Mellal. The magnetic survey reported here for the first time on this City’s topsoils tries to establish the link between magnetic properties and the content of heavy metals. High magnetic susceptibility values and high contents of heavy metals were found near the paved edge of the road and within the place reserved as large engine park. Magnetic extracts of highly polluted areas and unpolluted soil (olive plantation) were analyzed by SEM coupled with RDX in order to discriminate anthropogenic magnetic spherules and pedo-lithogenic magnetite-like minerals. Magnetic mineralogy determined by Mössbauer spectroscopy suggests the presence of hematite, magnetite and goethite in highly polluted areas. The iron oxides and especially goethite are efficient in incorporating and/or adsorbing foreign ions.     

Microbial load from animal feces at a recreational beach

The goal of this study was to quantify the microbial load (enterococci) contributed by the different animals that frequent a beach site. The highest enterococci concentrations were observed in dog feces with average levels of 3.9 × 10⁷ CFU/g; the next highest enterococci levels were observed in birds averaging 3.3 × 10⁵ CFU/g. The lowest measured levels of enterococci were observed in material collected from shrimp fecal mounds (2.0 CFU/g). A comparison of the microbial loads showed that 1 dog fecal event was equivalent to 6940 bird fecal events or 3.2 × 10⁸ shrimp fecal mounds. Comparing animal contributions to previously published numbers for human bather shedding indicates that one adult human swimmer contributes approximately the same microbial load as one bird fecal event. Given the abundance of animals observed on the beach, this study suggests that dogs are the largest contributing animal source of enterococci to the beach site.     

Radioactive occurrence in sediments of Cenozoic age near Bandha village,Jaisalmer district,Rajasthan

The radioactivity is dependent on the isotope and their concentration in the mineral such as potassium (K), uranium (U) and thorium (Th). In this paper the presence of a 3 to 5 m thick uranium and thorium bearing sediment of Cenozoic age is reported above Goru Formation of Jaisalmer basin. Gamma ray log response of Well-1 which falls under the study area has marked with very high GR (gamma ray) readings ranging from 350-1488 API coupled with high uranium and thorium content from spectral gamma ray log ranging from 92-178 ppm and 60-80 ppm respectively at the depth of 50 m from ground surface (-110m above MSL). Further studies are required to delineate the lateral thickness variation for mining purpose which may be a radioactive source.     

Sr–Nd isotopes and geochemistry of the infrastructural rocks in the Meatiq and Hafafit core complexes, Eastern Desert, Egypt: Evidence for involvement of pre-Neoproterozoic crust in the growth of Arabian–Nubian Shield

Abstract Meatiq and Hafafit core complexes are large swells in the Eastern Desert of Egypt, comprising two major tectono‐stratigraphic units or tiers. The lower (infrastructure) unit is composed of variably cataclased gneissose granites and high‐grade gneisses and schists. It is structurally overlain by Pan–African ophiolitic mélange nappes (the higher unit). The two units are separated by a low‐angle sole thrust, along which mylonites are developed. Major and trace element data indicate formation of the gneissose granites in both volcanic arc and within‐plate settings. Nevertheless, all analyzed gneissose granites and other infrastructural rocks, exhibit low initial ratios (Sr_i) (<0.7027), positive ε_Nd(t) (+4.9 to +10.3) and Neoproterozoic Nd model age (T_DM) (592–831 Ma for the gneissose granite samples). Although these values are compatible with other parts of the Arabian– Nubian Shield considered to be juvenile, the ε_Nd(t) values and several incompatible element ratios of the gneissose granites are too low to be derived from a mantle source without contribution from an older continental crust. Our geological, Sr–Nd isotopic and chemical data combined with the published zircon ages indicate the existence of a pre‐Neoproterozoic continent in the Eastern Desert that started to break up at ca 800 Ma. Rifting and subsequent events caused the formation of oceanic crust and emplacement within‐plate alkali basalts in the hinterland domains of the old continent. The emplacement of basaltic magma might have triggered melting of lower crust in the old continent and resulted in emplacement of the within‐plate granite masses between 700 Ma and 626 Ma. The granite masses and other rocks in the old continent have been subjected to deformation during the over‐thrusting of Pan–African nappes, probably because of the oblique convergence between East and West Gondwanaland. Rb–Sr isotopes of the gneissose granites in both Meatiq and Hafafit core complexes defines an isochron age of 619 ± 25 Ma with Sr_i of 0.7009 ± 0.0017 and mean squares of weighted deviates = 2.0. We interpret this age as the date of thrusting of the Pan–African nappes in the Eastern Desert. Continued oblique convergence between East and West Gondwanaland could have resulted in the formation northwest–southeast‐trending Meatiq and Hafafit anticlinoriums.     

The Radiative-Dynamical Effects of High Cloud on Global Ozone Distribution

Previous studies (e.g., Dessler et al., 1996; Haigh, 1984) have discussed the effect of cloud on modelled ozone distribution through changes in the radiative heating in the lower stratosphere. Here the relationship is investigated using an interactive chemical-radiative- transport 2D model. It is shown that, while similar cooling in the lower stratosphere due to high cloud is found, the effect on ozone is not as previously expected. The inclusion of high cloud is found to bring about a warming of the troposphere, resulting in a net heating in the lower stratosphere. This strengthens the circulation, leading to a decrease in total tropical ozone. Importantly, the effect of the cloud-induced temperature changes on heating rates does not combine linearly with the direct radiative effect of cloud changes. The possibility of a link between the high cloud increases and total ozone decreases observed in some regions during strong El Niño episodes is investigated. The possible impact on ozone of a global trend in high cloud cover is also discussed.     

Spectral properties of shocked accretion flows— a self-consistent study

Magnetized accretion flows around black holes which include standing or oscillating shock waves can produce very realistic spectrum till a few MeV. These shocks accelerate hot electrons which produce power-law spectrum. The post-shock region intercepts soft-photons from an external source, namely, a Keplerian disk and also from distributed sources such as the synchrotron photons emitted from thermal and non-thermal electrons originated in the pre-shock and post-shock flow. These photons are inverse Comptonized by the thermal and the non-thermal electrons present in the CENBOL region. Computations show that the emitted radiation is extended till a few MeV. We include the bulk motion Comptonization as well and discuss its importance vis-a-vis the power-law spectrum produced by non-thermal electrons.      

Testing of photochemical theory with solar occultation data

We have investigated the problem of testing photochemical theory using solar occultation data. We show, simply using a diurnal model, that for many steady-state relationships sunrise and sunset are not good times for performing quantitative tests. Departures should be expected between the true profile of a substance and that derived using a steady-state argument. Critical tests of theory can, however, be made by considering what we call the rate ratio of a species. A rate ratio, ø, is defined as the ratio of the rate of production to the rate of loss of the species under consideration. This is a simple way to quantify departures from steady-state. Using ATMOS data rate ratios for NO₂, ClONO₂. HNO₄ and N₂O₅ have been evaluated. These can then be compared with theoretical (model) predictions of the relevant rate ratio. The tests performed confirm our general understanding of the chemistry controlling these species. To make firm conclusions, the measurement of all the relevant parameters would be required. The usefulness in applying rate ratios to measurements made at occultation times is demonstrated.     

A workflow for decision making under uncertainty

We propose a workflow for decision making under uncertainty aiming at comparing different field development plan scenarios. The approach applies to mature fields where the residual uncertainty is estimated using a probabilistic inversion approach. Moreover, a robust optimization method is presented to optimize controllable parameters in the presence of uncertainty. The key element of this approach is the use of response surface model to reduce the very high number of simulator model evaluations that are classically needed to perform such workflows. The major issue is to be able to build an efficient and reliable response surface. This is achieved using a Gaussian process (kriging) statistical model and using a particular training set (experimental design) developed to take into account the variable correlation induced by the probabilistic inversion process. For the problem of optimization under uncertainty, an iterative training set is proposed, aiming at refining the response surface iteratively such as to effectively reduce approximation errors and converging faster to the true solution. The workflow is illustrated on a realistic test case of a mature field where the approach is used to compare two new development plan scenarios both in terms of expectation and of risk mitigation and to optimize well position parameters in the presence of uncertainty.