Relationships between sagittal otolith size and body size of Terapon jarbua (Teleostei,Terapontidae) in Malaysian waters

Journal of Oceanology and Limnology - Length-weight relationship provides basic information of a fish’s condition while the morphometric data of otolith has been traditionally used to...     

Geochemical study of peridotites from the Manipur Ophiolite Complex,Northeast India with special reference to their PGE concentration

The peridotites of the Manipur Ophiolite Complex (MOC) have been examined based on mineral chemistry, major elements and PGE contents. They represent high-magnesian cumulates with Mg# > 0.90 (Mg/Mg+Fe) in olivine and Cr# > 0.12 (Cr/Cr+Al) in spinel. High Mg* contents of the olivine show that these rocks are most likely derived from partial melting of the residual upper mantle. The peridotites contain higher concentration of Palladium Group PGE (PPGE) (Rh=4.4−6.6ppb; Pd=336−458ppb and Pt=14.6−36.4ppb) than the Iridium Group PGE (IPGE) (Os=2.4−5.8ppb; Ir=3.2−4.16ppb and Ru=5.2−7ppb). These are characterized by overall enrichment of PGE concentration (σPGE=365.8 − 516.6 ppb) and high ratio of (Pt+Pd)/(Os+Ir+Ru). This suggests that the rocks are formed by partial melting and crystal fractionation of olivine-rich (picritic) magma.     

Modeling forest fire risk in the northeast of Iran using remote sensing and GIS techniques

Fire in forested areas can be regarded as an environmental disaster which is triggered by either natural forces or anthropogenic activities. Fires are one of the major hazards in forested and grassland areas in the north of Iran. Control of fire is difficult, but it is feasible to map fire risk by geospatial technologies and thereby minimize the frequency of fire occurrences and damages caused by fire. The fire risk models provide a suitable concept to understand characterization of fire risk. Some models are map based, and they combine effectively different forest fire–causing variables with remote sensing data in a GIS environment for identifying and mapping forest fire risk. In this study, Structural Fire Index, Fire Risk Index, and a new index called Hybrid Fire Index were used to delineate fire risk in northeastern Iran that is subjected to frequent forest fire. Vegetation moisture, slope, aspect, elevation, distance from roads, and vicinity to settlements were used as the factors influencing accidental fire starts. These indices were set up by assigning subjective weight values to the classes of the layers based on their sensitivity ratio to fire. Hot spots data derived from MODIS satellite sensor were used to validate the indices. Assessment of the indices with receiver operating characteristic (ROC) curves shows that 76.7 % accuracy of the HFI outperformed the other two indices. According to the Hybrid Fire Index, 57.5 % of the study area is located under high-risk zone, 33 % in medium-risk zone, and the remaining 9.5 % area is located in low-risk zone.     

The influence of negatively charged heavy ions on the kinetic Alfven wave in a cometary environment

Kinetic Alfven waves are important in a wide variety of areas like astrophysical, space and laboratory plasmas. In cometary environments, waves in the hydromagnetic range of frequencies are excited predominantly by heavy ions. We, therefore, study the stability of the kinetic Alfven wave in a plasma of hydrogen ions, positively and negatively charged oxygen ions and electrons. Each species was modeled by drifting ring distributions in the direction parallel to the magnetic field; in the perpendicular direction the distribution was simulated with a loss cone type distribution obtained through the subtraction of two Maxwellian distributions with different temperatures. We find that for frequencies w^* < w_{cH ⁺}\omega^{*} < \omega_{c\mathrm{H}^{ +}} (ω ^∗ and w_{cH ⁺}\omega_{c\mathrm{H}^{ +}} being respectively the Doppler shifted and hydrogen ion gyro-frequencies), the growth rate increases with increasing negatively charged oxygen ion densities while decreasing with increasing propagation angles, negative ion temperatures and negative ion mass.     

Assessment of genotoxic and humoral immune system alterations in silica exposed workers from pottery industries in South India

Chemicals, especially silica, have been suspected to cause genetic alterations in pottery industry workers. The present study aims to analyze the frequency of chromosomal aberrations (CA), micronucleus (MN) and DNA damage (comet assay) in the peripheral blood lymphocytes and the immunological alterations workers chronically exposed to silica and in control subjects. In our study, 50 silica exposed workers and 35 control subjects were recruited and silica level was measured by respirable dust and respirable quartz concentrations of badge dosimeter. The serum immunoglobulins (IgM, IgG, and IgA) of all the subjects were measured by using ELISA method. The individuals exposed to silica have a significant increase in the frequency of CA, MN and the total DNA damage (p < 0.05). Immunoglobulin elevation on silica exposed workers was statistically significant (p < 0.05) on comparison with their respective controls. Investigation of the smoking and alcohol habitats coupled with silica exposure in exposed and control subjects represents alcohol consumption and smoking as additional risk factors and must be avoided. Multiple linear regression analysis obtained for CA, MN and comet assay confirm these tests as biomarkers for silica exposed pottery workers. Some confounding factors also showed significant influence on exposed subjects. These results indicate the mutagenic risk in the working environment has a high probability of association with the silica dust exposure in pottery industries. Nevertheless, the present study will create awareness and public concern not only among the silica exposed workers but also to the welfare of their progeny.     

Multivariate statistical approach to identify significant sources influencing the physico-chemical variables in Aerial Bay,North Andaman,India

Aerial Bay is one of the harbor towns of Andaman and Nicobar Islands, the union territory of India. Nevertheless, it is least studied marine environment, particularly for physico-chemical assessment. Therefore, to evaluate the annual spatiotemporal variations of physico-chemical parameters, seawater samples collected from 20 sampling stations covering three seasons were analyzed. Multivariate statistics is applied to the investigated data in an attempt to understand the causes of variation in physico-chemical parameters. Cluster analysis distinguished mangrove and open sea stations from other areas by considering distinctive physico-chemical characteristics. Factor analysis revealed 79.5% of total variance in physico-chemical parameters. Strong loading included transparency, TSS, DO, BOD, salinity, nitrate, nitrite, inorganic phosphate, total phosphorus and silicate. In addition, box-whisker plots and Geographical Information System based land use data further facilitated and supported multivariate results.     

Developing a biosorbent from <Emphasis Type="Italic">Aegle Marmelos</Emphasis> leaves for removal of methylene blue from water

Dried, mature leaves of Aegle Marmelos tree were converted to a powder, which was used as a biosorbent for dyes in water with methylene blue as a case study. The biosorbent had a surface area of 52.63 mg/g, and FTIR spectra showed the presence of –COOH, –NH₂, –R–SC=O (thioester) and R1–S(=O, =O)-N(–R2, –R3) groups on the surface. The particles were found to be porous in nature from scanning electron micrographs, and EDX measurements showed the elements C, O, Na, Mg, K, Ca and Fe on the surface. Batch adsorption experiments showed that the adsorption of the dye was preferred at near-neutral conditions. Adsorption equilibrium was achieved in ~120 min with maximum dye uptake of 19.9 mg/g. Investigation into the kinetics of adsorption indicated that second-order kinetics gave the best fit to the experimental data, and a rate coefficient of 8.0 × 10^?2 to 32.3 × 10^?2 g mg^?1 min^?1 was obtained.     

Delineation of groundwater potential zones and electrical resistivity studies for groundwater exploration

The electrical resistivity method is widely used in groundwater exploration studies. The method is particularly well suited to carry out groundwater studies in hard-rock terrains. The popular Schlumberger method of electrode configuration was applied in the study area. In all, 112 vertical electrical soundings (VESs) were carried out at different locations in the study area. VES interpretations were used to generate a top-layer contour map and a depth-to-basement map. Finally, a groundwater quality/potential map for the study area was generated using the depth-to-bedrock map, a water-level fluctuation map, and the second-layer thickness. Furthermore, this groundwater potential map was classified into three sectors, i.e. poor, moderate and good zones with respect to the prospects of finding groundwater in the study area. This map has a practical value, as it provides guidance to farmers in selecting favourable well sites, thereby avoiding unnecessary financial losses.     

Modelling of 2016 Kumamoto earthquake by integrating site effect in semi-empirical technique

Natural Hazards - The 2016 Kumamoto earthquake (MJMA7.3) struck central area of Kyushu Island, Japan. The presence of near surface low velocity layer greatly amplified the ground motions and caused...     

Geospatial modelling for identification of potential ecological corridors in Orissa

Development of forest connectivity and corridors are critical for biodiversity conservation and also ensures energy and genetic exchange across greater spatial extent. A model has been developed to geospatially identify the potential ecological corridors based on the vegetation type and land cover data in association with spatial disturbance profile. The model formulates the route of least impedance due to (1) disturbance (a function of fragmentation, juxtaposition, Interspersion & proximity to roads/settlements) and (2) vegetation type and land cover. This is because the movement of genetic information and materials follow the path of least resistance across a landscape. The paper explores the utility of the approach to spatially generate ecological corridors connecting 14 protected areas of Orissa. The model has been able to identify the potential route connecting the different protected regions with 85–87% of the corridor in the natural areas. Of the 14 protected areas, only 12 could be connected by the model as they confirm to the criteria for the corridor establishment.