Estimation of radioactive leakages into the Pacific Ocean due to Fukushima nuclear accident

High concentrations of several radionuclides were reported in the sea near the Fukushima Daiichi Nuclear Power Station (FDNPS) in Japan due to the nuclear accident that occurred on 11 March 2011. The main source of these concentrations was leakage of highly radioactive liquid effluent from a pit in the turbine building near the intake canal of Unit-2 of FDNPS through a crack in the concrete wall. In the immediate vicinity of the plant, seawater concentrations reached 68 MBq m^?3 for ¹³⁴Cs and ¹³⁷Cs, and exceeded 100 MBq m^?3 for ¹³¹I in early April 2011. These concentrations began to fall as of 11 April 2011 and, at the end of April, had reached a value close to 0.1 MBq m^?3 for ¹³⁷Cs. Following the nuclear accident, the Tokyo Electric Power Company (TEPCO) had initiated intense monitoring of the environment including the Pacific Ocean. Seawater samples were collected and the concentrations of few radionuclides were measured on a wide spatial and temporal scale. In this study, the measured concentrations of different radionuclides near the south discharge canal of the FDNPS were used to estimate their leakages into the Pacific Ocean. The method is based on estimating the release rates that reproduce the concentration of radionuclides in seawater at a chosen location using a two-dimensional advection–dispersion model in an iterative manner. The radioactive leakages were estimated as 5.68 PBq for ¹³¹I, 2.24 PBq for ¹³⁴Cs and 2.25 PBq for ¹³⁷Cs. Leakages were also estimated for ^99mTc, ¹³⁶Cs, ¹⁴⁰Ba and ¹⁴⁰La and they range between 0.02 PBq (^99mTc) and 0.53 PBq (¹⁴⁰Ba). It was estimated that about 11.28 PBq of radioactivity in total was leaked into the Pacific Ocean from the damaged FDNPS. Out of this, ¹³¹I constitutes 50.3 %; ¹³⁴Cs 20 %; ¹³⁷Cs 20 %; ¹⁴⁰Ba 4.6 %; ¹³⁶Cs 2.6 %; ¹⁴⁰La 2.3 % and ^99mTc 0.2 % of the total radioactive leakage. Such quantitative estimates of radioactive leakages are essential prerequisites for short-term and local-scale as well as long-term and large-scale radiological impact assessment of the nuclear accident.     

Strain estimation from single forms of distorted fossils — A computer graphics and MATLAB approach

Most of the existing methods of strain analysis can estimate strain in a single form of distorted brachiopod, or trilobite provided independent evidence, such as the association of the fossil with cleavage and/or stretching lineation is available for inferring the direction of maximum principal strain. This article proposes a simple computer graphics based method and its MATLAB code that determine the minimum amount of strain in a single distorted fossil form even if data for inferring the maximum principal strain direction are lacking. Our method is a rapid computer-graphics alternative to some of the existing analytical methods. In a distorted fossil form of original bilateral symmetry, the relative senses of angular shears along the hinge line and the median line are mutually opposite to each other. It follows, therefore, that the maximum principal strain direction lies within the acute angle between the hinge and the median lines in the plane of the fossil. Using this principle, our method performs several simulations such that each simulation retrodeforms the distorted fossil by assuming a particular orientation, lying within the acute angle between the hinge line and the median line, as the potential direction of the maximum principal strain. Each simulation of retrodeformation yields a potential strain ratio. The distribution of all the potential strain ratios, obtained by assuming different orientations as the potential directions of the maximum strain, is typically a parabola-like curve with a distinct vertex that corresponds to the minimum amount of strain in the distorted fossil. An entirely computer graphical approach is somewhat time-intensive because it involves a large number of retrodeformational simulations. We, therefore, give a MATLAB code, namely, the Minstrain, that rapidly retrodeforms the fossil and determines the minimum strain with precision.     

Pseudo-Dynamic Active Response of Non-Vertical Retaining Wall Supporting c-Φ Backfill

Knowledge of seismic active earth pressure behind rigid retaining wall is very important. In this paper, the pseudo-dynamic approach, which considers the effect of both compression and shear wave propagation, is adopted to calculate the seismic active force supporting c-Φ backfill. Considering a planar rupture surface, the effect of wide range of parameters like inclination of retaining wall, wall friction and soil friction angle, shear wave and compression wave velocity, horizontal and vertical seismic coefficients are taken into account to evaluate the seismic active force. Results are presented in terms of seismic coefficients in tabular form and variation of pressure with depth.     

Quantification and classification of ship scraping waste at Alang-Sosiya, India

Alang–Sosiya located on the Western Coast of Gulf of Cambay, is the largest ship recycling yard in the world. Every year on average 365 ships having a mean weight (2.10 × 10⁶ ± 7.82 × 10⁵ LDT) are scrapped. This industry generates a huge quantity of solid waste in the form of broken wood, rubber, insulation materials, paper, metals, glass and ceramics, plastics, leather, textiles, food waste, chemicals, paints, thermocol, sponge, ash, oil mixed sponges, miscellaneous combustible and non-combustible. The quantity and composition of solid waste was collected for a period of three months and the average values are presented in this work. Sosiya had the most waste 15.63 kg/m² compared to Alang 10.19 kg/m². The combustible solid waste quantity was around 83.0% of the total solid waste available at the yard, which represents an average weight of 9.807 kg/m²; whereas, non-combustible waste is 1.933 kg/m². There is not much difference between the average of total solid waste calculated from the sampling data (96.71 MT/day) and the data provided by the port authorities (96.8 MT/day).     

Role of crustal heterogeneity beneath Andaman–Nicobar Islands and its implications for coastal hazard

The Andaman–Nicobar (A–N) Islands region has attracted many geo-scientists because of its unique location and complex geotectonic settings. The recent occurrence of tsunamis due to the megathrust tsunamigenic north Sumatra earthquake (Mw 9.3) with a series of aftershocks in the A–N region caused severe damage to the coastal regions of India and Indonesia. Several pieces of evidence suggest that the occurrence of earthquakes in the A–N region is related to its complex geodynamical processes. In this study, it has been inferred that deep-seated structural heterogeneities related to dehydration of the subducting Indian plate beneath the Island could have induced the process of brittle failure through crustal weakening to contribute immensely to the coastal hazard in the region. The present study based on 3-D P-wave tomography of the entire rupture zone of the A–N region using the aftershocks of the 2004 Sumatra–Andaman earthquake (Mw 9.3) clearly demonstrates the role of crustal heterogeneity in seismogenesis and in causing the strong shakings and tsunamis. The nature and extent of the imaged crustal heterogeneity beneath the A–N region may have facilitated the degree of damage and extent of coastal hazards in the region. The 3-D velocity heterogeneities reflect asperities that manifest what type of seismogenic layers exist beneath the region to dictate the size of earthquakes and thereby they help to assess the extent of earthquake vulnerability in the coastal regions. The inference of this study may be used as one of the potential inputs for assessment of seismic vulnerability to the region, which may be considered for evolving earthquake hazard mitigation model for the coastal areas of the Andaman–Nicobar Islands region.     

Multi-scale assessment of invasive plant species diversity using Pléiades 1A,RapidEye and Landsat-8 data

We used a full remote sensing-based approach to assess plant species diversity in large and inaccessible areas affected by Lantana camara L., a common invasive species within the deciduous forests of Western Himalayan region of India, using spectral heterogeneity information extracted from optical data. The spread of L. camara was precisely mapped by Pléiades 1A data, followed by comparing Pléiades 1A, RapidEye and Landsat-8 OLI – assessed plant species diversities in invaded areas. The single plant species analysis was improved by Pléiades 1A-based diversity analysis, and higher species diversity values were observed for mixed vegetation cover. Furthermore, lower Coefficient of Variation and Renyi diversity values were observed where L. camara was the only species, while higher variations were observed in areas with a mixed spectral reflectance. This study was concluded to add a crucial baseline to the previous studies on remote sensing-based solutions for rapid estimation of biodiversity attributes.     

Study of star formation in RCW 106 using far-infrared observations

High-resolution far-infrared observations of a large area of the star-forming complex RCW 106 obtained using the TIFR 1-m balloon-borne telescope are presented. Intensity maps have been obtained simultaneously in two bands centred around 150 and 210 μm. Intensity maps have also been obtained in the four IRAS bands using HIRES-processed IRAS data. From the 150- and 210-μm maps, reliable maps of dust temperature and optical depth have been generated. The star formation in this complex has occurred in five linear sub-clumps. Using the map at 210 μm, which has a spatial resolution superior to that of IRAS at 100 μm, 23 sources have been identified. The spectral energy distribution (SED) and luminosity of these sources have been determined using the associations with the IRAS maps. The luminosity distribution of these sources has been obtained. Assuming these embedded sources to be zero-age main-sequence stars and using the mass–luminosity relation for these, the power-law slope of the initial mass function is found to be −1.73±0.5 . This index for this very young complex is about the same as that for more evolved complexes and clusters. Radiation transfer calculations in spherically symmetric geometry have been undertaken to fit the SEDs of 13 sources with fluxes in both the TIFR and the IRAS bands. From this, the r ⁻² density distribution in the envelopes is ruled out. Finally, a correlation is seen between the luminosity of embedded sources and the computed dust masses of the envelopes.     

Singhbhum Shear Zone: Structural transition and a kinematic model

The northern fold belt away from the Singhbhum Shear Zone displays a set of folds on bedding. The folds are sub-horizontal with E-W to ESE striking steep axial surfaces. In contrast, the folds in the Singhbhum Shear Zone developed on a mylonitic foliation and have a reclined geometry with northerly trending axes. There is a transitional zone between the two, where the bedding and the cleavage have become parallel by isoclinal folding and two sets of reclined folds have developed by deforming the bedding—parallel cleavage. Southward from the northern fold belt the intensity of deformation increases, the folds become tightened and overturned towards the south while the fold hinges are rotated from the sub-horizontal position to a down-dip attitude. Recognition of the transitional zone and the identification of the overlapping character of deformation in the shear zone and the northern belt enable the formulation of a bulk kinematic model for the area as a whole.     

Forest cover change prediction using hybrid methodology of geoinformatics and Markov chain model: A case study on sub-Himalayan town Gangtok,India

In the Himalayan states of India, with increasing population and activities, large areas of forested land are being converted into other land-use features. There is a definite cause and effect relationship between changing practice for development and changes in land use. So, an estimation of land use dynamics and a futuristic trend pattern is essential. A combination of geospatial and statistical techniques were applied to assess the present and future land use/land cover scenario of Gangtok, the subHimalayan capital of Sikkim. Multi-temporal satellite imageries of the Landsat series were used to map the changes in land use of Gangtok from 1990 to 2010. Only three major land use classes (built-up area and bare land, step cultivated area, and forest) were considered as the most dynamic land use practices of Gangtok. The conventional supervised classification, and spectral indices-based thresholding using NDVI (Normalized Difference Vegetation Index) and SAVI (Soil Adjusted Vegetation Index) were applied along with the accuracy assessments. Markov modelling was applied for prediction of land use/land cover change and was validated. SAVI provides the most accurate estimate, i.e., the difference between predicted and actual data is minimal. Finally, a combination of Markov modelling and SAVI was used to predict the probable land-use scenario in Gangtok in 2020 AD, which indicted that more forest areas will be converted for step cultivation by the year 2020.     

Characteristics of an open coast tidal flat: Example from Daman,west coast of India

This study highlights lithofacies and biofacies characteristics of the open coast tidal flat near Daman on the eastern flank of Gulf of Khambhat. Sedimentological and biological observation record six facies within the tidal flat area including older beach, beach face, sand flat, mud flat/mixed flat, sand bar and beach rock. Distinct sedimentary structures, foraminiferal assemblage and bioturbation intensity characterize each facies. A wide variety of wave and current generated sedimentary features characterize the sand flat facies. Semiconsolidated sands of older beach running parallel the coastline at a level higher than the present beach face possibly records the latest sea level highstand. The beach rock reflects early cementation of sands in tropical environments. Foraminifera are widely distributed in sand flats, mixed flats and mud flats and grouped into two biofacies — Ammonia-Elphidium-Quinqueloculina biofacies (sand flat and mixed flat) and Trochammina-Miliammina biofacies (mud flats). The beach face and sand bar facies contain forminifera reworked from sand flat and mud/mixed flat. Seasonal variation in depositional style is marked by deposition of fresh mud deposited over large areas of the intertidal flat during monsoon time, most of which is washed away by waves and current actions well before the onset of the next monsoon.