The plasma condensation region in the coma of Halley's Comet

The cometary images taken on 1986 January 8.590 and 8.638 UT (R-0.9 AU, ~ 1.29 AU) at Gurushikhar, Mt. Abu, India (24 °39 N, 72 °43 E alt: 1700 m) show distinct condensation region in the tail direction. The size of the condensation region is 4 × 10³ km. The condensation region showed up strongly in the blue emission, implying the abundance of CO⁺. It was inferred to be moving with a velocity of 37 ± 3 km/s relative to the comet at a distance of 2.3 × 10⁵ km from the nucleus in the tailward direction.The analysis show that the condensation was a result of rapid ionization mechanism, with a time scale of \~10³ to 10⁴ sec. The most probable mechanism for producing the ionization region was found to be the discharge of cross tail electric current passing through the neutral sheet in the near nucleus region followed by an outburst observed in IR wavelengths at 8.1 UT. It was accelerated by J × B drift at a rate of ~24 cm/sec² to the position observed by us.This feature, most probably is the precursor of the first dramatic Disconnection Event (DE) observed in Halley's Comet at Jan.10.375 UT. This supports the conjecture that the tail features originate in the coma with a velocity of ~20–40 km/s.     

Dissolved Organic Carbon in Multilayered Aquifers of Pondicherry Region (India): Spatial and Temporal Variability and Relationships to Major Ion Chemistry

Carbon, which is an essential element found in rocks and minerals, is used by biologically diverse life forms as a source of energy. Natural organic carbon is mainly derived from decomposing vegetation and other organic matter in the soil zone. Dissolved organic carbon (DOC) is an important component in biogeochemical cycling of elements characterized by high susceptibility to leaching. The significance of DOC was studied in layered coastal aquifers of the Pondicherry region during four different seasons. Pondicherry region has varied geological setup ranging from Cretaceous to Recent formations. A total of 324 groundwater samples were collected from various aquifers, namely Alluvium, Tertiary, Cretaceous, and Mixed formations, during different seasons of pre-monsoon, southwest monsoon, northeast monsoon, and post-monsoon. The samples were analyzed for major ions and DOC. The range of DOC in the study area is 0–10 mg/l. Very high DOC concentrations were measured in most of the samples from Alluvium and Upper Cuddalore Formation and in few samples from the Lower Cuddalore Formation. The relationships of DOC with other ions in this study indicate that the hydrochemistry of groundwater was controlled by both aerobic and anaerobic environments in the different formations of the study area.     

A package for digital processing and automatic contouring of aeromagnetic data

Aeromagnetic data processing refers to the processing of magnetic data acquired through airborne surveys. The total magnetic field at various points along the predetermined flight path is recorded using the on board cesium magnetometer. At each of these points, the positional information in terms of latitude, longitude obtained from Inertial Navigation System (INS) and attitude, time and date are also recorded. The track flown by the aircraft while data acquisition is also recorded using video flight path camera. A software package has been developed to process this data and generate outputs in a form amenable to visual interpretation. It is developed on a VAX 11/780 system using VAX FORTRAN and PLOT 10 GKS software. This paper gives an outline of the various functions available in this package and also highlights the problems encountered in choosing the most appropriate techniques/methods to be used in the gridding and contouring of the data.     

Heavy metal contamination in sediments of Balanagar industrial area,Hyderabad, Andra Pradesh,India

Environmental geochemical studies were carried out to find out the extent of contamination in sediments due to heavy metals in Balanagar industrial area, Hyderabad, Andhra Pradesh, India. The industrial area consisting of 350 small and large industries manufacturing battery, steel planting, pharmaceutical chemicals, metal plating, etc. The present study was undertaken on sediment contamination in Balanagar industrial area, to determine extent and distribution of heavy metals (Cu, Cr, Ni, Pb, Zn, As) and to delineate the source. There is no treatment plant in the industrial area, and many industries release the effluents into nearby nalas and lakes. Solid waste from the industries is also being dumped along the roads and near the open grounds due to which heavy metals migrate from solid waste to the groundwater. The sediments samples were collected from the study area in clean polythene covers and were analyzed for their heavy metals by X-ray fluorescence spectrometry. The concentration ranges of different heavy metals were Cr, 96.2–439.6 mg/kg; Cu, 95.7–810 mg/kg; Ni, 32.3–13,068.2 mg/kg; Pb, 59.2–512 mg/kg; Zn, 157.1–4,630.5 mg/kg; Co, 1.8–48.3 mg/kg; and V, 35.2–308.5 mg/kg. High concentration of heavy metals in sediments can be attributed to some pharmaceutical and metal industries in the study area. Based on the results obtained, suitable remedial measures can be adopted such as phytoremediation and bio-remediation for reduction of heavy metals in sediments.     

A study on the high fluoride concentration in the magnesium-rich waters of hard rock aquifer in Krishnagiri district, Tamilnadu, India

Excess fluoride in groundwater affects the human health and results in dental and skeletal fluorosis. Higher concentration of fluoride was noted in hard rock terrain of the south India, in the Krishnagiri district of Tamilnadu. The region has a complex geology ranging from ultra basic to acid igneous rocks, charnockite and gneissic rocks. Thirty-four groundwater samples were collected from this study area and analysed for major cations and anions along with fluoride. The order of dominance of cations is Na⁺?>?Mg²⁺?>?Ca²⁺?>?K⁺ and the anions in the following order HCO₃ ^??>?Cl^??>?NO₃ ^??>?SO₄ ^2?. It is found that nearly 58 % of the samples have more fluoride ranging from 1 to 3 mg/L. It is also noted that high fluoride waters correspond to magnesium water types. This is due to the release of fluoride from the magnesium-bearing minerals like, biotite, hornblende, etc., or weathering of apatite/hydroxyapatites found in charnockites.     

Identification of the geochemical processes in groundwater by factor analysis in hard rock aquifers of Madurai District,South India

A study was carried out in the Madurai district of Tamil Nadu, India to identify the hydrogeochemical processes using factor analysis as a predictive tool. It also focuses on characterizing the samples of these factors with respect to standard geochemical plots. In order to obtain a synoptic view of the statistics and the geochemical processes, a total of 53 groundwater samples are collected representing the entire district. The major ions were analyzed; the order of ion dominance are Ca²⁺?>?Na⁺?>?Mg²⁺?>?K⁺?=?Cl^??>?HCO^? ₃?>?H₄SiO^? ₄?>?NO^? ₃?>?SO^2? ₄?>?P^3? ₄. The samples are classified according to three factors. Factor 1 shows strong positive loadings of Cl^?, Ca²⁺, Mg²⁺, and NO^? ₃ with 36.98 % of the total variance (TV); factor 2 accounts for 13.72 % of TV with high loadings of Na⁺, K⁺, and HCO^? ₃; and factor 3 shows strong positive loadings of PO^3? ₄ and SO^2? ₄ with TV of 13.1 %. In the Piper plot, few samples fall in the mix region as evidenced by the mixing proportion of two samples using AQUACHEM software. The results suggest that different hydrogeochemical processes, like weathering, ion exchange processes, and anthropogenic activities (like sewage infiltration and agriculture), has predominant impact in the study area. Thus, the study highlights the factor analysis technique as a predictive and effective tool for groundwater evolution.     

Long-term spatial and temporal trends in frost indices in Kansas, USA

Frost indices such as number of frost days (nFDs), number of frost-free days (nFFDs), last spring freeze (LSF), first fall freeze (FFF), and growing-season length (GSL) were calculated using daily minimum air temperature (T_min) from 23 centennial weather stations across Kansas during four time periods (through 1919, 1920–1949, 1950–1979, and 1980–2009). A frost day is defined as a day with T_min?<?0 °C. The long- and short-term trends in frost indices were analyzed at monthly, seasonal, and annual timescales. Probability of occurrence of the indices was analyzed at 5 %, 25 %, 50 %, 75 %, and 95 %. Results indicated a general increase in T_min from 1900 through 2009 causing a decrease in nFDs. LSF and FFF occurred earlier and later than normal in the year, respectively, thereby resulting in an increase in GSL. In general, northwest Kansas recorded the greatest nFD and lowest T_min, whereas southeast Kansas had the lowest nFD and highest T_min; however, the magnitude of the trends in these indices varied with location, time period, and time scales. Based on the long-term records in most stations, LSF occurred earlier by 0.1–1.9 days/decade, FFF occurred later by 0.2–0.9 day/decade, and GSL was longer by 0.1–2.5 day/decade. At the 50 % probability level, Independence in the south-eastern part of Kansas had the earliest LSF (6 April), latest FFF (29 October) and longest GSL (207 days). Oberlin (north-western Kansas) recorded the shortest GSL (156 days) and earliest FFF (7 October) had the latest LSF (2 May) at the 50 % probability level. A positive correlation was observed for combinations of indices (LSF and GSL) and elevation, whereas a negative correlation was found between FFF and elevation.     

Assessment of heavy metal contamination in soils around Balanagar industrial area,Hyderabad, India

The concentration of heavy metals such as Ba, Co, Cr, Cu, Ni, Pb, Rb, Sr, V, Y, Zn, Zr were studied in soils of Balanagar industrial area, Hyderabad to understand heavy metal contamination due to industrialization and urbanization. This area is affected by the industrial activities like steel, petrochemicals, automobiles, refineries, and battery manufacturing generating hazardous wastes. The assessment of the contamination of the soils was based on the geoaccumulation index, enrichment factor (EF), contamination factor, and degree of contamination. Soil samples were collected from Balanagar industrial area from top 10–50 cm layer of soil. The samples were analyzed using X-ray fluorescence spectrometer for heavy metals. The data revealed that the soils in the study area are significantly contaminated, showing high level of toxic elements than normal distribution. The ranges of concentration of Cr (82.2–2,264 mg/kg), Cu (31.3–1,040 mg/kg), Ni (34.3–289.4 mg/kg), Pb (57.5–1,274 mg/kg), Zn (67.5–5819.5 mg/kg), Co (8.6–54.8 mg/kg), and V (66.6–297 mg/kg). The concentration of above-mentioned other elements was similar to the levels in the earth’s crust pointed to metal depletion in the soil as the EF was <1. Some heavy metals showed high EF in the soil samples indicating that there is a considerable heavy metal pollution, which could be correlated with the industries in the area. A contamination site poses significant environmental hazards for terrestrial and aquatic ecosystems. They are important sources of pollution and may results in ecotoxicological effects on terrestrial, groundwater and aquatic ecosystems.     

A study on the factors affecting the stable isotopic composition in precipitation of Tamil Nadu,India

Stable isotope measurements in precipitation help us to form the basic inference about the origin and the state of water in different environments. The precipitation samples collected during the South West Monsoon (SWM) during August 2007 from 37 different locations in the state help in deriving the first preliminary local meteoric water line (LMWL) for the Tamil Nadu State. The study reveals that there are three main sources of water vapours, namely South East Arabian Sea (SEAS), Indian Ocean (IO) and evaporation from local water bodies. There are wide variations in the altitude and amount of rainfall received in the state. It is also noted that there is a significant variation in the latitude and the distance from the coast. Hence, an attempt is made in this paper to study the factors controlling the composition of stable isotopes in precipitation with reference to amount of rainfall, latitude, altitude and the continental effect. The altitude and continental effect shows good correlation to the variations in stable isotope composition. Copyright © 2009 John Wiley & Sons, Ltd.