Mycorrhizal Colonization Affects the Survival of Vetiveria zizanioides (L.) Nash Grown in Water Containing As(III)

The presence of arsenic (As) in water is of great public concern. Arsenic exists in three common valence states viz., As(0) metalloid arsenic, As(III) (arsenite) and As(V) (arsenate). Arsenite [As(III)] is the most toxic form among arsenicals which, predominates in anaerobic conditions, generally in flooded soils and in the water with high BOD. Experiments were conducted to investigate the effect of As(III) on the mycorrhization in vetiver (Vetiveria zizanioides (L.) Nash) grass in hydroponics. Studies showed significant alteration in the mycorrhizal colonization in the roots of vetiver exposed to higher concentrations of As(III) starting from 1.0, 2.0, 3.0, 4.0 to 5.0 mg/L prepared in 5% Hoagland nutrient solution without addition of phosphate ions. Considerable reduction in the mycorrhizal intensity (M) was observed in all the treatment sets as compared to the control suggesting a negative impact of the As(III) on the mycorrhizal association. Simultaneously, the study also showed that, As(III) is toxic to the vetiver plants having mycorrhizal association however plants with non‐mycorrhizal (cleansed) roots were found to be able to survive for a longer period exposed to As(III).     

Finite Element and Reliability Analyses for Slope Stability of Subansiri Lower Hydroelectric Project: A Case Study

The partly constructed and excavated power house slopes of Subansiri Lower Hydroelectric Project experienced extensive collapses through complex mode of failure. A detailed study is attempted in this paper to understand the reasons for the failure and assess the stability of the existing constructed slopes using limit equilibrium and FEM solutions and also to propose modified design for rebuilding the slopes. To take into account the uncertainty associated with the rockmass and soil properties, probability and reliability analyses have also been carried out. Based on the field observations and stability analyses of the natural and cut slopes, suitable support systems such as slope flattening with various angles, weldmesh, shotcrete, rockbolts and drainage holes have been considered to meet the stability requirements. In this study, it is demonstrated that the probabilistic approach when used in conjunction with deterministic approach helps in providing a rational solution for quantification of stability in the estimation of risk associated with the power house slope construction.     

Relationship between interplanetary (IP) parameters and geomagnetic indices during IP shock events of 2005

In the present study, we investigate the possible relationship of IP parameters of solar wind and interplanetary magnetic field with ground-based geomagnetic indices. To carry out the study, we take all the IP shock events listed by Proton Monitor onboard Solar and Heliospheric Observatory (SOHO) during 2005, and plot the time variations of all the IP parameters and geomagnetic parameters (±5 days), centered at the shock arrival time. Next, we obtain scatter plots of absolute values of solar wind parameters such as Vsw, Nsw and Interplanetary Magnetic Field (IMF) components Bx, By, Bz and total B with the values of geomagnetic parameters such as Dst, Kp indices, dayside Magnetopause (MP) distance and Cosmic-Ray Neutron Monitor count (CRNM). The scatter plots show that before the IP shock, the pattern is random with no clear relationship. Following the shock, a clear pattern emerges with a type of relationship being seen — clear for SHARP shocks and less clear for DIFFUSE shocks. A total of 10 shock events for 2005 have been studied. Typical examples of this behaviour are the shock events of January 21, 2005 and May 15, 2005. Our study suggests a definite correlation between changes in the solar wind and interplanetary magnetic field parameters and ground-based geomagnetic response. We are trying to obtain quantitative relationships between these for shock events of 2005.     

Energy dependence of near-relativistic electron spectrum at geostationary orbit during the SEP events of 2005

In view of the renewed interest in the study of energetic particles in the outer radiation belt of the earth, we feel it will be helpful in looking for the energy dependence of the electron energy spectrum at geostationary orbit. This may give us some insight into how we can safeguard geostationary satellites from functional anomalies of the deep dielectric charging type, which are caused by charge accumulation and subsequent discharge of relativistic electrons. In this study we examine whether there is any energy dependence in relativistic electron enhancements at geosynchronous altitudes during solar energetic proton events of 2005.     

NUMERICAL METHOD OF PUMPING TEST ANALYSIS USING MICROCOMPUTERS

Abstract. This paper describes how a numerical method of pumping test analysis, which has proved to be useful in many practical situations, can be run on microcomputers. Full details of a program in BASIC and a test problem are provided. The need to perform all the calculations to a sufficient accuracy is stressed, and the choice of suitable mesh spacings and time steps is discussed.     

Effective Removal of Microorganisms and Biostimulants of Wastewater by the Application of Various Electrolytes

A variety of electrolytes FeCl₃, CaCl₂, CuSO₄, Al₂(SO₄)₃, and LaCl₃ was investigated for their efficiency in removing biostimulants (phosphorous and nitrogen) to improve the water quality. Results show that the removal of PO₄^3– was achieved below the detection limit (BDL) by two electrolytes, CuSO₄ and Al₂(SO₄)₃, and up to 1.0 ± 0.0 mg/L by LaCl₃ from a value of 15.0 mg/L, of the concentration of PO₄^3– in amended water. The turbidity was found to be removed significantly by FeCl₃, CuSO₄, and Al₂(SO₄)₃ by about 5.8 ± 2.6, 9.7 ± 1.0, and 5.4 ± 1.1 nephalometric turbidity unit (NTU), respectively. The removal of the members of Enterobacteriaceae viz., Escherichia coli, Enterobacter spp. Pseudomonas fluorescence, and Pseudomonas spp. was found almost in all the chemical precipitants but their removal was more significant in the water samples treated with CuSO₄, Al₂(SO₄)₃, and LaCl₃. To achieve a complete removal and to sustain the after effects of precipitation, such as recurrence of algal growth, the combination of CuSO₄ and Al₂(SO₄)₃ was investigated. Reduction in the turbidity from 30.83 to <2 NTU, phosphate ion from a value of 1.28 mg/L to BDL and ammonia ion from a value of 44.71 to 36.48 mg/L of natural pond water were observed after the treatment with CuSO₄ and Al₂(SO₄)₃ in combination.     

Mineralogy and geochemistry of picro-dolerite dykes from the central Deccan Traps flood basaltic province,India, and their geodynamic significance

Mineralogy and Petrology - Constituent mineral compositions and whole rock major element geochemistry of picro-dolerite dykes from the central part of the Deccan flood basalt province are presented...