Assessment of sources and distribution metals in groundwater of Pondicherry region, India

The proposed study investigates the seasonal variation in the concentration and the source of the heavy metals like Mn, Cu, Pb, Zn and Fe in the groundwater samples of Pondicherry region. The study results reveal that, the heavy metal concentration is high during South West Monsoon season (SWM) compared to that of North East Monsoon season (NEM). The pH was near neutral and metal load representing most of the samples were low during NEM. Statistical analysis shows that the 63.7 % of the total variance is observed during NEM and 68.9% during SWM. Geographic information system (GIS) tool was considered for the study to understand the environmental pollution status of the groundwater systems of the study area and to identify the groundwater quality parameters. The multivariate statistical analysis explains that the source of trace metal in the groundwater is derived from natural origin except copper and lead as these contaminants were derived from anthropogenic activities. Based on the output of WATEQ4F, several species of heavy metals exist, in which the dominant species are Mn, CuCl2, PbCO3, Fe and Zn

Strengthening of Load Bearing Masonry Wall Panels with Externally Bonded Precast Textile Reinforced Concrete Laminate

241-245Textile Reinforced Concrete (TRC) has gained worldwide popularity as a strengthening material for masonry structures in the recent years. As of today, the application of TRC for masonry strengthening is either by cast-in-place methodology or by spraying method. The present work is a first-of-its kind study, which explores the feasibility of using externally bonded precast TRC laminate for strengthening of load bearing brick masonry wall panels. The binder used in TRC itself is used as adhesive for adhering the TRC laminate to masonry wall panels. Experimental investigations were carried out on unstrengthened and strengthened brick masonry wall panels under axial compression and combined axial compression and shear loading. The influence of TRC strengthening system is assessed by examining the performance indicators such as strength, stiffness and deformation. Based on the investigations, the use of externally bonded precast TRC laminate is found to be a feasible solution to strengthen brick masonry walls to have the required structural adequacy

A study on the defluoridation in water by using natural soil

Removal of excess fluoride (F−) from the water has been attempted by several authors by using different materials both natural and artificial. The main aim of this paper was to attempt the fluoride removal by using the locally available red soil adopting column method. The red soil was mixed in different proportion with sand in order to increase the porosity and permeability property of the medium. It was optimized for 4:1 ratio of red soil to sand and it was used for the following experiment. The experiment was conducted in 11 batches for a period of about 9,213 min. Fresh standard solution of F was used in each batch, prepared from Orion 1,000 ppm solution. The samples were collected and analyzed for pH, EC (Electrical Conductivity) and HCO3. Rate of flow of water and efficiency of adsorption were calculated and compared with the fluoride removal capacities of the medium. The medium used for the fluoride removal was subjected to FTIR analysis before and after the experiment. The variation of IR spectrum before and after treatment signifies the changes in the OH bonding between Al and Fe ions present in the soil. The variation in pH decreased during the course of defluoridation. Higher F removal was noted when flow rate was lesser. An attempt on the regeneration of the fluoride adsorbed soil was also made and found to be effective

Age-dependent favorable visual recovery despite significant retinal atrophy in pediatric MOGAD: how much retina do you really need to see well?

BACKGROUND To investigate age-related severity, patterns of retinal structural damage, and functional visual recovery in pediatric and adult cohorts of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) optic neuritis (ON). METHODS All MOGAD patients from the 5 participating centers were included. Patients with initial manifestation 0.5) visual impairment. Independent of retinal atrophy, age at ON onset significantly correlated with visual outcome. CONCLUSION Pediatric MOGAD ON showed better visual recovery than adult MOGAD ON despite profound and almost identical neuroaxonal retinal atrophy. Age-related cortical neuroplasticity may account for the substantial discrepancy between structural changes and functional outcomes

Variable Stars in Galactic Globular Clusters

Based on a search of the literature up to May 2001, the number of known variable stars in Galactic globular clusters is approximately 3000. Of these, more than 2200 have known periods and the majority (approximately 1800) are of the RR Lyrae type. In addition to the RR Lyrae population, there are approximately 100 eclipsing binaries, 120 SX Phe variables, 60 Cepheids (including population II Cepheids, anomalous Cepheids and RV Tauri) and 120 SR/red variables. The mean period of the fundamental mode RR Lyrae variables is 0.585, for the overtone variables it is 0.342 (0.349 for the first-overtone pulsators and 0.296 for the second-overtone pulsators) and approximately 30% are overtone pulsators. These numbers indicate that about 65% of RR Lyrae variables in Galactic globular clusters belong to Oosterhoff type I systems. The mean period of the RR Lyrae variables in the Oosterhoff type I clusters seems to be correlated with metal abundance in the sense that the periods are longer in the more metal poor clusters. Such a correlation does not exist for the Oosterhoff type II clusters. Most of the Cepheids are in clusters with blue horizontal branches.Comment: 45 pages, 10 figures, to be published in AJ November 200

Identification of Recharge Processes in Groundwater in Hard Rock Aquifers of Madurai District Using Stable Isotopes

Stable isotopes of H and O are the integral parts of water molecule and serve as ideal tracers to understand the recharge processes in groundwater. Hence, a study has been conducted in hard rock aquifers of Madurai District of Tamilnadu to identify the recharge processes using stable isotopes. A total of 54 groundwater samples were collected representing the entire district from various lithounits during post monsoon. Samples were analysed for pH, EC, Ca2+, Mg2+, Na+, K+, Cl− HCO3−, SO42−, PO43−, H4SiO4, F−, δ18O and δD. Cl− and HCO3− were the dominant ions in groundwater samples. Average values of Cl− and HCO3− ranged from 247 and 244 mg/L in fissile hornblende biotite gneiss, 262 and 268 mg/L in Charnockite, 75 and 185 mg/L in quartzite, 323 and 305 mg/L in granite, 524 and 253 mg/L in floodplain alluvium rock types. Geochemical signatures of groundwater were used to identify the chemical processes that control hydrogeochemistry. Interpretation of δ18O and δD indicates recharge from the meteoric water in charnockite, quartzite, granite and some samples of fissile hornblende biotite gneiss. It is also inferred that recharge take place from evaporated water in floodplain alluvium and fissile hornblende biotite gneiss

Hydrochemical Characteristics and Groundwater Quality Assessment in Krishnagiri District, Tamilnadu, India

The hydrochemical characteristics of groundwater in Krishnagiri district, Tamilnadu have been evaluated based on different indices for drinking, irrigation and industrial uses. Groundwater samples were collected from 34 boreholes and analyzed for chemical parameters. The abundance of the major ions is in order of: Na+ > Mg2+ > Ca2+ > K+ and HCO3- > Cl-> NO3- > SO4 2-. Interpretation of analytical data shows three major hydrochemical facies: Ca-HCO3, Ca-Na-HCO3 and Ca-Mg-Cl. The concentration of Ca2+ and SO4 2- is well within the desirable limit in all the locations. The SAR, RSC and Na% showsthat most of the samples are suitable for irrigation. High values of TH and CR at manylocations restrict its use for industrial purpose

A Study on the Behaviour of Total Carbon and Dissolved Organic Carbon in Groundwaters of Pondicherry Region, India

Organic carbon concentrations can vary considerably, both spatially and temporally, so a large number of analyses are frequently required to produce a representative estimate of concentrations. Natural organic carbon is mainly derived from decomposing vegetation and other organic matter in the soil zone. In this scenario, a baseline attempt was made to study the behaviour of organic carbon content in groundwater by collecting samples from the layered aquifer sequence of Pondicherry. The samples were collected from Recent Alluvium (30), Upper Cuddalore(13), Lower Cuddalore (13), Other Tertiary formation (7), Mixed aquifer (5) and Cretaceous formations (24). The analysis of these samples show that higher concentration of Dissolved Organic Carbon (DOC) was noted in the Alluvial formation and the average concentration was higher in Upper Cuddalore Formation. The samples of these formations were compared with pH, Ionic strength, and log pCO2 and bicarbonate concentration. The alluvial aquifer shows that pH governed dissolution along the coastal tracts and in Upper Cuddalore formation it’s based on interaction between aquifer matrix and groundwater

A multivariate statistical approach to identify the spatio-temporal variation of geochemical process in a hard rock aquifer

A study has been carried out in crystalline hard rock aquifers of Madurai district, Tamil Nadu, to identify the spatial and temporal variations and to understand sources responsible for hydrogeochemical processes in the region. Totally, 216 samples were collected for four seasons [premonsoon (PRM), southwest monsoon (SWM), northeast monsoon (NWM), and postmonsoon (POM)]. The Na and K ions are attributed from weathering of feldspars in charnockite and fissile hornblende gneiss. The results also indicate that monsoon leaches the U ions in the groundwater and later it is reflected in the 222Rn levels also. The statistical relationship on the temporal data reflects the fact that Ca, Mg, Na, Cl, HCO3, and SO4 form the spinal species, which are the chief ions playing the significant role in the geochemistry of the region. The factor loadings of the temporal data reveal the fact that the predominant factor is anthropogenic process and followed by natural weathering and U dissolution. The spatial analysis of the temporal data reveals that weathering is prominent in the NW part and that of distribution of U and 222Rn along the NE part of the study area. This is also reflected in the cluster analysis, and it is understood that lithology, land use pattern, lineaments, and groundwater flow direction determine the spatial variation of these ions with respect to season