Biopolymer-biocement composite treatment for stabilisation of soil against both current and wave erosion

Acta Geotechnica - Increased frequency of extreme weather events has made the conservation of riverbanks and coastlines a global concern. Soil stabilisation via microbially induced calcite...     

Lamprey (Geotria australis; Agnatha) reddening syndrome in Southland rivers,New Zealand 2011–2013: laboratory findings and epidemiology,including the incidental detection of an atypical Aeromonas salmonicida

From 2011, lamprey (Geotria australis) populations in Southland, New Zealand have been affected by reddening along the length of the body and increased mortalities, termed lamprey reddening syndrome (LRS). Molecular testing, bacteriology, histopathology and epidemiology were used to determine if an infectious agent was present and to increase the understanding of this syndrome. An atypical Aeromonas salmonicida was detected from affected lamprey in 2011. This organism has not previously been reported from New Zealand. Investigative molecular testing indicated the organism was an uncharacterised, unculturable, atypical A. salmonicida and a likely incidental finding. Histopathology did not indicate an infectious process was involved, but suggested the reddening may be due to blunt trauma. Epidemiological investigation found the Mokoreta River had a significantly higher prevalence of LRS than others in the Southland region, but there was no clear reason why. To date, no infectious aetiology for this syndrome has been identified.     

Deformation of the rocks of Simla Hills

Simla Hills form a part of Lesser Himalaya. Metamorphic rocks of this area (Pre-Cambrian), forming Chail-Jutogh nappe, are thrust over a series of mostly unfossiliferous rock formations ranging in age from Palaeozoic to Eocene. The rocks of the area are characterised by meso-structures belonging to three phases of deformation. The second phase structures, both in the allochthon as well as in the para-autochthon units are synchronous with the nappe formation. The third structure in the para-autochthon unit has been related with the movement of nappe. A model explaining the probable kinematics of thrusting in the Simla Hills has been suggested.

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Zusammenfassung Die Simla-Berge sind ein Teil des Lesser Himalaya. Metamorphe Gesteine dieses Gebietes (Präkambrium), die die Chail-Jutogh-Decke bilden, sind über einer Serie vorwiegend fossilfreier Formationen (Paläozoikum bis Eozän) überschoben. Die Gesteine dieses Gebietes sind durch Meso-Strukturen, die zu drei Phasen der Deformation gehören, gekennzeichnet. Die Strukturen der zweiten Phase, zu der allochthone sowie para-autochthone Einheiten gehören, sind gleichaltrig mit der Anlage der Deckenbildung. Die Strukturen der dritten Phase in der para-autochthonen Einheit hängen mit der weiteren Bewegung der Decke zusammen. Ein Modell, das die wahrscheinliche Kinematik der Überschiebung in den Simla-Bergen erklärt, wird vorgeschlagen.

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Résumé Les monts Simla représentent une partie du « Lesser Himalaya ». Les roches métamorphiques de cette région (Précambrien), formant la nappe du « Chail-Jutogh », ont glissé par-dessus une série de formations (du Paléozoique à l'Eocène) en majorité dépourvues de fossiles. Les roches de cette région sont caractérisées par des interstructures appartenant à trois phases de la déformation. Les structures de la 2^e phase, auxquelles appartiennent les unités allochtones et para-autochtones se sont formées en même temps que la nappe. Les structures de la 3^e phase, dans l'unité para-autochtone, sont en rapport étroit avec le déplacement postérieur de la nappe. Une possibilité d'explication de la cinématique probable du glissement dans les monts Simla est proposée.

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Simla Lesser Himalaya. — —, Chail-Jutogh, , - . -, . - , - , . - . , , , .

     

Depositional environment of mudflats and mangroves and bioavailability of selected metals within mudflats in a tropical estuary

Four sediment cores representing adjacent mudflat and mangrove sub-environments of middle estuary (Shastri) were analyzed for sand, silt, clay, and organic carbon. Total metal concentration of iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn), chromium (Cr), copper (Cu), cobalt (Co), and lead (Pb) and chemical speciation of Fe, Mn, and Co on selected samples was also carried out on mudflat cores. The sediments in the upper middle estuary were found to be deposited under highly varying hydrodynamic energy conditions; whereas lower middle estuary experienced relatively stable hydrodynamic energy conditions with time. The tributary joining the river near the upper middle estuary is found to be responsible for the addition of enhanced organic carbon and metal concentrations. Speciation study indicated Fe and Co are from natural lithogenic origin while Mn is derived from anthropogenic sources. Higher Mn and Co than apparent effects threshold can pose a high risk of toxicity to organisms associated with these sediments.     

Comparison of a simple logarithmic and equivalent neutral wind approaches for converting buoy-measured wind speed to the standard height: special emphasis to North Indian Ocean

The difference between the transferred wind speed to 10-m height based on the equivalent neutral wind approach (U _n) and the logarithmic approach (U _log) is studied using in situ observations from the Indian, Pacific, and Atlantic Oceans, with special emphasis given to the North Indian Ocean. The study included U _n ? U _log variations with pressure, relative humidity, wind speed, air temperature, and sea surface temperature (SST). U _n ? U _log variation with respect to air temperature (T _a) reveals that U _n ? U _log is out of phase with air temperature. Further analysis found that U _n ? U _log is in phase with SST (T _s) ? T _a and varies between ?1.0 and 1.0 m/s over the North Indian Ocean, while for the rest of the Oceans, it is between ?0.3 and 0.8 m/s. This higher magnitude of U _n ? U _log over the North Indian Ocean is due to the higher range of T _s ? T _a (?4 to 6 °C) in the North Indian Ocean. Associated physical processes suggested that the roughness length and friction velocity dependence on the air–sea temperature difference contributes to the U _n ? U _log difference. The study is further extended to evaluate the behavior of U _n ? U _log under cyclonic conditions (winds between 15 and 30 m/s), and it was found that the magnitude of U_n ? U _log varies 0.5–1.5 m/s under the cyclonic wind conditions. The increasing difference with the wind speed is due to the increase in the momentum transfer coefficient with wind speed, which modifies the friction velocity significantly, resulting in U _n higher than U _log. Thus, under higher wind conditions, U _n ? U _log can contribute up to half the retrieval error (5 % of the wind speed magnitude) to the satellite validation exercise.     

Determination of the particle load based on detailed suspended sediment measurements at a hydropower plant

Suspended sediment particles contained in inflows of water systems of hydropower plants (HPPs) cause hydro-abrasive erosion of the hydraulic turbines and structures leading to significant maintenance costs, efficiency reductions, and downtime. Relevant parameters such as suspended sediment concentration (SSC), particle size distribution (PSD), shape, and mineralogical composition were measured with an online multi-frequency acoustic instrument and based on manually taken samples from the end of the sand trap of the Toss HPP in the Himalayan region, India. In the laboratory, the samples were analyzed using the gravimetric method, laser diffraction, turbidity, dynamic digital image processing, scanning electron microscope, petrography analysis, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The online instrument and the samples provided measurement results at a single point. To investigate vertical gradients in concentration and particle sizes, additional samples were collected 9 times at 7 relative water depths. The SSC, most particle sizes, and particle shape were found to be evenly distributed over depth except d90, i.e. the diameter which is not exceeded by 90% of the particle mass. d90 measured at 76% of the water depth was in the range of fine sand and was multiplied by 1.05 to obtain an average value representative for the entire depth. Improved methodologies to quantify both particle shape and size in an analytical model for hydro-abrasive erosion are proposed. Also, the PSD measuring performance of laser diffraction and dynamic imaging was studied and similar values of the median particle sizes were obtained from both instruments. Further, multi-frequency acoustic, turbidity and laser diffraction techniques were found suitable for SSC measurement at the test case HPP.     

On computation of strain‐dependent permeability of rocks and rock‐like porous media

Determination of transport properties of geomaterials is an important issue in many fields of engineering analysis and design. For example, in petroleum engineering, in situ permeability of an oil reservoir may be crucial in establishing its viability for exploitation, whilst prevention of leakage from underground storage facilities for oil and gas, nuclear waste as well as viability of CO₂ sequestration projects crucially depends on its long‐term values. Permeability is indirectly related to the porosity, pore‐size distribution and pore architecture of the porous media. These parameters evolve when a strain field is imposed. Physical measurement of permeability under a strain field in laboratory conditions is difficult, expensive and prone to a number of uncertainties. In the past, pore network models have been used to compute permeability of materials under stress/strain‐free conditions. In this paper, we propose an enhanced pore network model to compute permeability of rocks and rock‐like porous media under a stress/strain field. Data of pore‐size distribution obtained from mercury intrusion porosimetry are used to compute permeability of rock samples from various unspecified oilfields in the world. It is shown that the two permeabilities can be predicted from the model with sufficient accuracy. A hypothesis for change in porosity, pore‐size distribution and pore architecture as a result of imposed mechanical strains is then proposed. Based on this, permeability is computed again for one of the rock samples under uniaxial and triaxial compressive and tensile strain fields. It is shown that depending on the state of strain field imposed, permeability evolves in an anisotropic manner. Permeability under tensile strain field increases dramatically compared with the reduction that takes place under compressive strain field of the same magnitude. Copyright © 2014 John Wiley & Sons, Ltd.     

Biochemical‐genetic variation in a wild and a cultured population of the greenshell mussel,Perna canaliculus

A wild and a cultured greenshell mussel (Perna canaliculus) population were compared for biochemical genetic variation at seven polymorphic and four monomorphic allozyme loci. Significant heterozygote deficiencies were observed for all polymorphic loci (La—1, La—2, Lap, Lgg—1, Lgg— 2, Pgi, and Pgm) for both populations (except the Pgi locus of the wild mussel population). Genotypic disequilibrium was calculated for both populations: genotypic frequencies were significantly non‐random at three pairs of loci among the wild mussels, and significantly non‐random at three different pairs of loci among the cultured mussels. All six pairs of loci which exhibited significant genotypic disequilibrium involved amino‐peptidases, suggesting that these loci form a linkage group, and that neither the Pgi nor the Pgm loci are associated with this group. Exact tests for population differentiation based upon population‐specific allele distributions indicated that four of the polymorphic loci were significantly heterogeneous among the two populations, whereas the remaining three polymorphic loci were not. Based upon the private allele system, the number of migrants (N _m) between the populations was estimated to be 2.009, which, according to the private allele system, represents a high level of gene flow. These findings are discussed with regard to the population biology and genetic structure of this species.     

Radioactive quartz-pebble conglomerates from western margin of Bonai granite pluton,Sundargarh district,Orissa — A new find

Several radioactive quartz-pebble conglomerate (QPC) occurrences at the western margin of Archaean Bonai granite and overlying Iron Ore Group (IOG) rocks have recently been located over a total strike length of 8–10 km intermittently in a NE-SW to E-W trend with steep dips due north-west to north in parts of Sundargarh district of Orissa. The QPC samples have analysed up to 0.039% U₃O₈ and 0.035% ThO₂ with high concentration of Y (74 to 518 ppm), La(<100 to 880 ppm), Cr ( 126 to 633 ppm), Zr (137 to 1250 ppm) and Pb (31 to 581 ppm). Cellulose Nitrate (CN) film studies of few QPC samples indicated adsorbed uranium over goethite and infiltrated ferruginous material (limonite), secondary uranium as encrustation and fracture filling and discrete sub-rounded grains of monazite, zircon, allanite and rare xenotime in the matrix of QPC as radioactive phases. Higher content of Th over U, elevated concentration of Y and La in QPC eliminates the possibility of its low temperature product by epigenetic processes. Poor correlation of U with elements like Pb, Y, Zr, La and Cr can be explained due to surficial leaching of uranium from QPC after its deposition as reflected by adsorbed U over iron-oxides and low U/Th ratio in QPC in the area.     

Irrotational motion in quiescent prominences

On the basis of Kippenhahn and Schlüter's magnetohydrostatic model of a quiescent prominence, an attempt has been made to study the effect of irrotational motion existing in the prominences on the magnetic field pattern in it, introducing an irrotational velocity field. It is found that, under such a condition, the magnetic field geometry in the model does not change.