A Statistical appraisal to hydrogeochemistry of fluoride contaminated ground water in Nayagarh district, Odisha

Seasonal variation of ground water in Nayagarh district, Odisha is determined by analysing both pre and post monsoon water samples. The high fluoride content is an endemic problem in the area and special attention was attached to the point. The chemical compositions of the ground water of the area are dominated by CaCl, NaCl and mixed CaMgCl types in pre-monsoon and CaHCO₃-mixed CaMgCl type in post-monsoon. This is largely due to chemical weathering of Eastern Ghats Mobile Belt rock types. Increasing alkalinity vis-a-vis F concentration in pre-monsoon is associated with sodium-bicarbonate water types having high pH (>7) and low calcium and magnesium contents. The percentage of total high fluoride containing water samples is nearly double in pre-monsoon than in post-monsoon. During both the seasons, pH values indicate mildly alkaline to weakly acidic nature of the water samples. Fluoride concentration has good correlation with pH in pre-monsoon whereas in post-monsoon it shows good correlation with Fe. Facies analysis indicates that water is becoming predominantly Ca-Na cation and Cl-SO₄-HCO₃ anion type in premonsoon than Ca-Mg type and HCO₃-Cl-SO₄ type in post-monsoon. The seasonal variations in concentrations of anthropogenic components demonstrate that the groundwater system is very less liable to pollution by human activities.     

http://www.sciencedirect.com/science/article/pii/S1674987113000546

In the eastern part of the Indian shield,late PaleozoiceMesozoic sedimentary rocks of the Talchir Basin lie precisely along a contact of Neoproterozoic age between granulites of the Eastern Ghats Mobile Belt(EGMB)and amphibolite facies rocks of the Rengali Province.At present,the northern part of the basin experiences periodic seismicity by reactivation of faults located both within the basin,and in the Rengali Province to the north.Detailed gravity data collected across the basin show that Bouguer anomalies decrease from the EGMB(wt15 mGal),through the basin(w 10 mGal),into the Rengali Province(w 15 mGal).The data are consistent with the reportedly uncompensated nature of the EGMB,and indicate that the crust below the Rengali Province has a cratonic gravity signature.The contact between the two domains with distinct sub-surface structure,inferred from gravity data,coincides with the North Orissa Boundary Fault(NOBF)that defnes the northern boundary of the Talchir Basin.Post-Gondwana faults are also localized along the northern margin of the basin,and present-day seismic tremors also have epicenters close to the NOBF.This indicates that the NOBF was formed by reactivation of a Neoproterozoic terrane boundary,and continues to be susceptible to seismic activity even at the present-day.     

Removal of Arsenic from Simulated Groundwater Using GAC‐Ca in Batch Reactor: Kinetics and Equilibrium Studies

This paper deals with kinetics and equilibrium studies on the adsorption of arsenic species from simulated groundwater containing arsenic (As(III)/As(V), 1:1), Fe, and Mn in concentrations of 0.188, 2.8, and 0.6 mg/L, respectively, by Ca²⁺ impregnated granular activated charcoal (GAC‐Ca). Effects of agitation period and initial arsenic concentration on the removal of arsenic species have also been described. Although, most of the arsenic species are adsorbed within 10 h of agitation, equilibrium reaches after ～24 h. Amongst various kinetic models investigated, the pseudo second order model is more adequate to explain the adsorption kinetics and film diffusion is found to be the rate controlling step for the adsorption of arsenic species on GAC‐Ca. Freundlich isotherm is adequate to explain the adsorption equilibrium. However, empirical polynomial isotherm gives more accurate prediction on equilibrium specific uptakes of arsenic species. Maximum specific uptake (q_max) for the adsorption of As(T) as obtained from Langmuir isotherm is 135 µg/g.     

Determination of Q β(f) in Different Parts of Kumaon Himalaya from the Inversion of Spectral Acceleration Data

This paper presents the results of a modified two-step inversion algorithm approach to find S wave quality factor Q _β(f) given by Joshi (Bull Seis Soc Am 96:2165–2180, 2006). Seismic moment is calculated from the source displacement spectra of the S wave using both horizontal components. Average value of seismic moment computed from two horizontal components recorded at several stations is used as an input to the first part of inversion together with the spectra of S phase in the acceleration record. Several values of the corner frequency have been selected iteratively and are used as inputs to the inversion algorithm. Solution corresponding to minimum root mean square error (RMSE) is used for obtaining the final estimate of Q _β(f) relation. The estimates of seismic moment, corner frequency and Q _β(f) from the first part of inversion are further used for obtaining the residual of theoretical and observed source spectra which are treated as site amplification terms. The acceleration record corrected for the site amplification term is used for determination of seismic moment from source spectra by using Q _β(f) obtained from first part of inversion. Corrected acceleration record and new estimate of seismic moment are used as inputs to the second part of the inversion scheme which is similar to the first part except for use of input data. The final outcome from this part of inversion is a new Q _β(f) relation together with known values of seismic moment and corner frequency of each input. The process of two-step inversion is repeated for this new estimate of seismic moment and goes on until minimum RMSE is obtained which gives final estimate of Q _β(f) at each station and corner frequency of input events. The Pithoragarh district in the state of Uttarakhand in India lies in the border region of India and Nepal and is part of the seismically active Kumaon Himalaya zone. A network of eight strong motion recorders has been installed in this region since March, 2006. In this study we have analyzed data from 18 local events recorded between March, 2006 and October, 2010 at various stations. These events have been located using HYPO71 and data has been used to obtain frequency-dependent shear-wave attenuation. The Q _β(f) at each station is calculated by using both the north-south (NS) and east-west (EW) components of acceleration records as inputs to the developed inversion algorithm. The average Q _β(f) values obtained from Q _β(f) values at different stations from both NS and EW components have been used to compute a regional average relationship for the Pithoragarh region of Kumaon Himalaya of form Q _β(f)?=?(29?±?1.2)f ^{(1.1 ± 0.06)}.     

A Study on Simulation of Heavy Rainfall Events Over Indian Region with ARW-3DVAR Modeling System

An attempt is made to evaluate the impact of the three dimensional variational (3DVAR) data assimilation within the Weather Research Forecasting (WRF) modeling system to simulate two heavy rainfall events which occured on 26–27 July 2005 and 27–30 July 2006. During the 26–27 July 2005 event, the unprecedented localized intense rainfall 90–100 cm was recorded over the northeast parts of Mumbai city; however, southern parts received only 10 cm. Model simulation with the data assimilation experiment is reasonably well predicted for the rainfall intensity (800 mm) in 24 h and with accurate location over Mumbai agreeing with observation. Divergence, vorticity, vertical velocity and moisture parameters are evaluated during the various stages of the event. It is noticed that maximum convergence and vorticity during the mature stage; at the same time the vertical velocity also follows a similar trend during the period in the assimilation experiment. Vorticity budget terms over the location of heavy rainfall revealed that the contribution of the positive tilting term produced positive vorticity which triggered the convection and negative contribution to vorticity from the tilting term to precede the dissipation of the system. Model simulations from the second rain event, the off-shore trough at sea level along the west coast of India, is well represented after assimilation of observations during day-1 and day-2 as compared to the control simulations; the orientation of the off-shore trough is well matched with that of the observed. The intensity and spatial distribution of the rainfall has considerably improved in the assimilation simulation. The statistical skill scores also revealed that the precipitation forecast during the period has appreciably improved due to assimilation of observations. The results of this study indicate a positive impact of the 3DVAR assimilation on the simulation of heavy rainfall events.     

Simulation of Bay of Bengal Tropical Cyclones with WRF Model: Impact of Initial and Boundary Conditions

An attempt is made to delineate the relative performances and credentials of GFS, FNL, and NCMRWF global analyses/forecast products as initial and boundary conditions (IBCs) to the WRF-ARW model in the simulation of four Bay of Bengal tropical cyclones (TCs). The results suggest that FNL could simulate horizontal advection of vorticity maxima at 850 hPa; hence, the tracks are more realistic with least errors as compared to GFS and NCMRWF. The mean landfall errors for 24-, 48-, and 72-hour forecasts are 73, 41, and 72 km, respectively. The TC intensity is well captured by NCMRWF IBCs, as it could predict 850 hPa vorticity maxima. The 24-hour accumulated rainfall is well simulated with FNL, and equitable threat score is more than 0.2 up to 100 mm with minimum bias.     

Comparative evaluation of performances of two versions of NCEP climate forecast system in predicting Indian summer monsoon rainfall

The operational prediction of climatic variables in monthly-to-seasonal scales has been issued by National Centers for Environmental Prediction (NCEP) through Climate Forecast System model (CFSv1) since 2004. After incorporating significant changes, a new version of this model (CFSv2) was released in 2011. The present study is based on the comparative evaluation of performances of CFSv2 and CFSv1 for the southwest monsoon season (June-July-August-September, JJAS) over India with May initial condition during 1982–2009. It was observed that CFSv2 has improved over CFSv1 in simulating the observed monsoon rainfall climatology and inter annual variability. The movement of the cell of Walker circulation in years of excessive and deficient rainfall is better captured in CFSv2, as well. The observed teleconnection pattern between ISMR-sea surface temperature (SST) is also better captured in CFSv2. The overall results suggest that the changes incorporated in CFSv1 through the development of CFSv2 have resulted in an improved prediction of ISMR.21     

Microtremor survey in Talchir, India to ascertain its basin characteristics in terms of predominant frequency by Nakamura's ratio technique

The Talchir Basin, one of India's oldest basins, has been a subject of interest because of its rich coal deposits. The maximum thickness of the basin is about 1500 m. Beyond the basin is the hard metamorphic rocks of Precambrian age. The ambient noise survey data have been analyzed for the Talchir Basin using Nakamura's technique of horizontal–vertical-spectral-ratio (HVSR) to ascertain the basin structure in terms of the predominant frequency. The predominant frequency varies from 0.25 Hz to 7.8 Hz but a major portion of the basin comes under the range of 0.3 Hz–2.4 Hz while on the metamorphic rocks it is as high as 7.8 Hz. The variation in predominant frequency shows a good correlation with the sediment thickness of the basin. The results have been compared with the previous studies by other researchers and it shows consistency with the northerly dip of the basin. The present study has also been compared with the results of the synthetic seismogram that was performed for the Talchir Basin. The predominant frequency obtained from HVSR technique complements well with the frequency at which the peak response spectra ratio is observed. The present study of the predominant frequency identifies quite well the characteristics of Talchir Basin and is in good agreement with the synthetic ground motion modeling of the region.     

Mesonic stiff fluid distribution in five dimensional Bianchi type space time

In this paper, we have constructed mesonic stiff fluid cosmological models in five dimensional LRS Bianchi type-I and Bianchi type-VI₀ space times in general theory of relativity. Some physical and geometrical properties of the models are discussed.