Toxicity of Phenol,Pentachlorophenol and Sodium Pentachlorophenolate to a Freshwater Teleost Lebistes reticulatus (Peters)

Lebistes reticulatus (Peters) was exposed to various concentrations of phenol, pentachlorophenol and sodium pentachlorophenolate to determine their toxicity, lethal concentrations and slope functions by a static bioassay procedure. Simultaneous controls were also run. The 94h LC₅₀ values were 47.5mg/l (42.04 … 53.68) for phenol, 0.77 mg/l (0.616 … 0.963) for sodium pentachlorophenate and 0.97 mg/l (0.866 … 1.086) for pentachlorophenol. On this basis, the rank order is sodium pentachlorophenolate-pentachlorophenol-phenol. During the treatment, fish showed an abnormal swimming reflex, excessive mucus secretion, haemorrhage near lips, abdomen and basis of fins and loss of equilibrium followed by death.     

Paleomagnetic study of Cambrian Potsdam Group sandstones,St. Lawrence Lowlands,Quebec

We report paleomagnetic results from oriented drill core samples collected at 10 sites (80 samples) from the Covey Hill and 19 sites (96 samples) from the overlying, fossiliferous Cha?teauguay Formations of the gently dipping Late Cambrian Potsdam Group sandstones exposed in the St. Lawrence Lowlands of Quebec. Stepwise thermal demagnetization analyses ave revealed the presence of two predominant groups of coherent magnetizations C-1 and C-2, after simple correction for bedding tilt. The C-1 group magnetization is a stable direction (D=332°, I=+18°) with unblocking temperatures (T_UB) between 550 and 650°C, present in the older Covey Hill Formation; this direction is probably a chemical remanence acquired during the Covey Hill diagenesis and carried predominantly by hematite. The C-2 group magnetization (D=322°, I=+9°) is present at 13 sites of the younger Cha?teauguay Formation; this is probably carried by magnetite and represents a penecontemporaneous, depositional DRM, characterized by T_UB spectra 400–550°C. We believe that C-2 is relatively younger than C-1 based on a combination of arguments such as the presence of opposite polarities, internal consistency, similarity and common occurrence of C-1 and C-2 respectively in the Covey Hill and Cha?teauguay members. The corresponding paleomagnetic poles C-1 (46°N, 149°E; dp, dm=3°, 5°) and C-2 (37°N, 156°E; dp, dm=2°, 5°) are not significantly different from most of the other Late Cambrian (Dresbachian-Franconian) poles derived from sediments exposed in the southern region (Texas) of the North American craton which are also believed to have been deposited during Croixian Sauk sea transgression similar to the Potsdam sandstones. Although adequate faunal control is lacking (in particular for the Covey Hill Formation), this comparison with the Cratonic poles suggests a Late Cambrian age to the Potsdam poles. The agreement between the results also gives the evidence for internal consistency of cratonic poles at least for Late Cambrian.The incoherent C-3 group remanence (D=250°, I=?15°) is commonly present at 7 sites in both the formations; this may not correspond to a reliable paleomagnetic signal. The other remanence C-4 (D=180°, I=+10°) is found only at 3 sites located in the uppermost stratigraphic levels of the Cha?teauguay Formation; the corresponding paleomagnetic pole (40°N, 107°E) does not differ significantly from the Ordovician and some Late Cambrian poles. The present data are insufficient to resolve a problem in apparent polar wander for Middle and Late Cambrian time posed by the existence of high-latitude poles for some strata of Middle Cambrian age and low-latitude poles for some strata of Late Cambrian age.     

Characteristic curves for interpreting gravity anomalies of vertical cylinders and horizontal circular discs

Characteristic curves for the complete interpretation of a wide range of parameters of a vertical cylinder and a horizontal circular disc are presented. It is established that the distance of the inflexion point on the gravity profile of a vertical cylinder from the point of maximum anomaly [i.e. the origin] is approximately equal to the radius of the vertical cylinder, thus enabling one to demarcate the boundary of the vertical cylinder directly from the contour map based on the cluster of contours. Two gravity profiles, one across an anomalous zone in central Alberta, Canada and the other over Borsad area, India are interpreted by the curves presented and the results are shown.     

Pyritized ooids,stringed ooids and reticulate tubular structures from within the black shale at Amjhor,Bihar, India

Carbonate ooids, notionally incompatible with an euxinic environment, and some curious reticulate tubular structures with fibrous carbonate walls are described from intraclasts occurring in Proterozoic black shales containing the pyrite deposit at Amjhor. While some of the tubes are visibly due to coalescence of ooids, others are interpreted as worm burrows on the basis of their strata-transgressive orientation, branching nature and larger diameter than those of the ooids.All stages of pyritization of ooids and tube-cores, displaying truncation of the growth-fabric of calcite grains by growing pyrite crystals, point to a late- or post-diagenetic age of pyritization. The clasts containing ooids and tubes are believed to have been transported from a shallow-bank and/or a nearshore environment into a lagoonal, euxinic basin. An environmental model, consistent with the observed data, is proposed to account for the ooid—black shale association.     

On observing mass ejections in the interplanetary medium

Scattering of radio waves by density fluctuations in the solar wind leads to rapid variation in the intensity of compact radio sources. This phenomenon, known as Interplanetary Scintillation (IPS), provides a simple method to study interplanetary activity in the inner heliosphere. During the solar maximum of cycle 22, we carried out extensive, high-time-resolution IPS observations of fast moving interplanetary plasma clouds (IPCs). The observations were done using the Ooty Radio Telescope (ORT) and covered the region between 0.2 AU and 0.8 AU around the Sun. We detected 33 IPCs having velocities of 600 to 1400 km s–1. A two-component model of scattering by time-varying solar wind was developed to analyse these IPCs. The model enabled us to estimate the mass, energy and geometry of each disturbance and to associate them with solar-geomagnetic activity.Detailed analysis suggests that these IPCs were interplanetary signatures of massive and energetic Solar Mass Ejections (SMEs). The SMEs were found to have average mass and kinetic energy of 5.3×1016 g, 2.4×1032 ergs. The average span and width of the SME was found to be 42° and 8×106 km. Association of these disturbances with solar-geomagnetic activity shows that about 80% of them are associated with Long-Duration X-ray Events (LDXE) and Solar Mass Ejections (SMEs). Only 50% of the events were associated with geomagnetic activity. The present experiment has demonstrated that continuous IPS monitoring is an effective technique to detect mass ejections in the interplanetary medium and to study their evolution through the inner heliosphere.     

Uptake of fluoride by serpentine

Fluoride uptake by serpentine depends on a number of parameters, viz. the chemical composition of serpentine, its particle size, pH of the medium, etc. Exchangeable (OH)^? in serpentine minerals is essential for fluoride uptake. Data are also presented indicating the existence of an equilibrium between the fluoride concentrations in the solution and that taken up by serpentine over a wide range of experimental conditions. The available evidence strongly suggests the proxy of F^? for (OH)^? group as contributing to the principal mechanism of the process.     

Photogeomorphic study of coastal features between visakhapatnam and pudimadaka in andhra pradesh

Journal of the Indian Society of Remote Sensing - In order to uuderstand the origin and disposition of some of the coastal landforms reported earlier by the authors from this area, aerial...     

Geomagnetic induction anomalies along the hyderabad—kalingapatnam profile

Observations of H- and Z-variations made at ten temporary field stations along the Hyderabad—Bhadrachalam—Kalingapatnam (east coast) profile during February–March, 1973, are analyzed and discussed. The results are also compared with those of the Alibag (west coast)—Hyderabad profile, completed in May–July, 1970.It is found that the Z-ranges of quiet daily variations are enhanced one and a half times the Hyderabad value, and the H-ranges only very slightly reduced at the coastal station of Kalingapatnam. This coastal effect of 6γ in Z_r at Kalingapatnam gradually decreases inland and probably exists upto Salur (70 km inland from the coast). At Bhadrachalam, both H- and Z-ranges of quiet daily variations are found to be enhanced, possibly due to induction effects from deep-seated conductors in the Godavari rift valley. The enhancement of both H and Z daily ranges at Jeypore in the eastern “ghats” (hills) is attributed to induced electric currents in conductors arising from the orogeny well below the “ghats”.It is difficult to separate the coastal effect from the orogenic effect, both of which seem to taper off and merge at Salur.