Central Tamil Nadu Research Articles

Selection of Optimum Enhancement Technique for the Discrimination of Alkali Granites and Syenites around Suryamalai Batholith of Central Tamil Nadu, India

Image processing techniques such as Band Ratio, Principal Component Analysis, Supervised, Unsupervised classification and Reclassification techniques are generally used as an enhancement technique for alteration zone demarcation and lithological discrimination in geosciences environment. In the present study, Landsat OLI satellite imagery has been utilized to produce various combinations of image enhancement to discriminate alkali syenite and alkali granite of Proterozoic age. These techniques were also used to differentiate three phases of granites reported in Suryamalai Batholith which is very difficult to map by conventional method due to its rugged topographic nature. 12 types of enhancement techniques were applied to differentiate rock alkali syenite from granite, however only few methods such as Kaufmanns ratio, ratio of 5/7, 3/1 and 3/5 and supervised classification were found to be suitable for the discrimination of those rocky types. Band ratio 5/7, 3/1 and 3/5, Crosta analysis and thermal reclassification techniques significantly brought to light the difference between the metamorphic rocks such as fissile hornblende biotite gneiss and hornblende biotite gneiss of Archaean age. Similarly, phase I and phase III granites were perfectly discriminated from all the image enhancement techniques. It is differentiated mainly based on its grain size and mineral variation between these two rock types. Study revealed that standard digital image processing technique can be effectively used for lithological mapping.

The past and current distribution of the lesser-known Indian endemic Madras Hedgehog Paraechinus nudiventris (Mammalia: Eulipotyphla: Erinaceidae)

The Madras Hedgehog Paraechinus nudiventris (Horsefield, 1851) is a species endemic to a few isolated patches in southern India threatened by habitat loss and direct take. Little is known about its historical distribution or present climatic needs, both of which could provide important baselines for conservation and habitat restoration. The current distribution of Paraechinus nudiventris was modelled using occurrences collected in the field and from community reports. Based on the current climatic niche estimated from Maxent, Madras Hedgehog distribution was projected into southern India during the last interglacial gap (120,000–140,000 YBP), and last glacial maximum (22,000 YBP) and mid-Holocene (~6,000 YBP). During the (Last Interglacial Gap) LIG the suitable habitat was restricted to the Palghat gap in the southern Western Ghats mountains and a small region in south Sri Lanka, although it is unclear whether the suitable climates in Sri Lanka were occupied and then extirpated, or never colonized. The present climatic niche of the species is confined to lower elevations and semi-arid plains of southern and central Tamil Nadu in India. The contemporary models can be used to update the IUCN range map for P. nudiventris in India, as well as identify suitable habitats for this species to guide local conservation strategies.

Distribution and Characterization of Heavy Mineral Placer Deposits along the Central Tamil Nadu Coast, India

Distribution and Characterization of Heavy Mineral Placer Deposits along the Central Tamil Nadu Coast, India

A Cross-Sectional Study on Knowledge, Attitude, Practice of COVID-19 Vaccines among General Population in Central Tamilnadu

A Cross-Sectional Study on Knowledge, Attitude, Practice of COVID-19 Vaccines among General Population in Central Tamilnadu

An economic appraisal of cultivation of korai grass in Central Tamilnadu

An economic appraisal of cultivation of korai grass in Central Tamilnadu

Correlation of stagnant wetland depths and their ecological status in the Central Tamil Nadu District, Tamil Nadu.

The wetland stagnation is the premise of the wetland depth (WD) but is lacking in detail. The research looks into the correlation of stagnant wetland's depth and their ecological status in the Central Tamil Nadu District (CTND) because of few studies. Seventy-five chosen stagnant wetlands are hydrologically isolated; depths were categorized into less than 5 ft., 6 to 10 and above 10 ft., surveyed by the range of methods from districts such as Karur (KD), Namakkal (ND) and Tiruchirappalli (TD). The human disturbance score (HDS) is categorized as least impacted (0-33), moderately impacted (33-67) and highly impacted (67-100). The impacts of land use and land cover (LULC) changes over 9years (2010-2019) through the maximum likelihood method. Overall, 54% of wetland depths (WD) were less than 5 ft.; 25.6% were 6-10 ft. and 20.2% were 100 ft. District-wise, wetland degradation was the utmost in the TD, followed by ND and KD. Except in KD, the remaining district wetlands were of MI category with diverse HDS. The correlation test revealed a positive relationship between WD against the alteration of the buffer zone, habitat, hydrology and HDS. However, it is a negative relationship between landscape alteration and wetland pollution. The impacts of land use and land cover (LULC) changes confirm that severe decline in wetlands habitat and water bodies' area is due to built-up area, cultivated land expansion and increasing population. Our study provided evidence that the WD is connected to wetland conditions that have a quantitative influence, and the ramifications of the findings were examined in the context of local development planning. Additional research will be needed due to limited surveyed wetlands with similar geographical locations.

Inferences on paleo-tsunami from the shoreline of Poompuhar, central Tamil Nadu coast, India through sedimentological and micropaleontological signatures

A 650 cm long sediment core collected from the Poompuhar beach was analyzed for sedimentological and foraminiferal studies. The specific absence of foraminifera and occurrences of coarser sands of low φ value of mean grain size from the bottom of the core up to 200 cm core depth reflects the dominant influence of the Cauvery river in the study area in the geological past. Further, the consistent occurrence of the appreciable number of marine microfossil - foraminifera and greater φ value of mean grain size of finer sands in top 200 cm core depth reflect the strong influence of marine environment indicating the coastal subsidence followed by marine transgression in this region. This distinct break in sedimentological and micropaleontological parameters at around 200 cm core depth could be due to the mega-tsunami events and associated phenomena such as coastal submergence, shifting of the river course, and reduced supply of sediments river in the study area around 1540 ± 25 years ago.

Redox conditions and nature of Pan-African granites from the E–W trending Cauvery Shear Zone, Southern Granulite Terrain of Central Tamil Nadu, India: Constraints from magnetic susceptibility and biotite chemistry

Redox conditions and nature of Pan-African granites from the E–W trending Cauvery Shear Zone, Southern Granulite Terrain of Central Tamil Nadu, India: Constraints from magnetic susceptibility and biotite chemistry

Health Risk Implication and Spatial Distribution of Radon in Groundwater Along the Lithological Contact in South India.

The presence of radioactive elements in groundwater results in high health risks on surrounding populations. Hence, a study was conducted in central Tamil Nadu, South India, to measure the radon levels in groundwater and determine the associatedhealth risk. The study was conducted along the lithological contact of hard rock and sedimentary formation. The concentrations of uranium (U) varied from 0.28 to 84.65µg/L, and the radioactivity of radon (Rn) varied from 258 to 7072Bq/m3 in the collected groundwater samples.The spatial distribution of Rn in the study area showed that higher values were identified along the central and northern regions of the study area. The data also indicate that granitic and gneissic rocks are the major contributors to Rn in groundwater through U-enriched lithological zones. The radon levels in all samples were below the maximum concentration level, prescribed by Environmental Protection Agency. The effective dose levels for ingestion and inhalation were calculated according to parameters introduced by UNSCEAR and were found to be lesser (0.235-6.453 μSvy-1) than the recommended limit. Hence, the regional groundwater in the study area does not pose any health risks to consumers. The spatial distribution of Rn's effective dose level indicates the higher values were mainly in the central and northern portion of the study area consist of gneissic, quarzitic, and granitic rocks. The present study showed that Rn concentrations in groundwater depend on the lithology, structural attributes, the existence of uranium minerals in rocks, and the redox conditions. The results of this study provide information on the spatial distribution of Rn in the groundwater and its potential health risk in central Tamil Nadu, India. It is anticipated that these data will help policymakers to develop plans for management of drinking water resources in the region.

Recent patterns of extreme temperature events over Tamil Nadu, India

We investigated the time evolution of heat waves and warm nights over the 7 agro-climatic zones of Tamil Nadu, India, during the period 1951-2016, including the spatiotemporal patterns of concurrent hot day and hot night (CHDHN) episodes and the concurrent warm spells in daytime temperature and drought (CWD) episodes. The research relied upon gridded temperature and rainfall observations from the India Meteorological Department. We used the Heat-Wave Magnitude Index daily to study the warm spells in daytime and nighttime temperature, while the analysis of droughts was based on the Standardized Precipitation Evapotranspiration Index. We observed a considerable increase in the count, intensity and duration of heat waves and warm night episodes across Tamil Nadu between the periods 1951-1983 and 1984-2016. Particularly, the number of heat wave events almost doubled in the second half of the study period. We observed a west-east gradient in the severity of heat waves. The intensity and duration of warm night events increased up to 3-fold in the second half of the study period, especially over central Tamil Nadu. The study recorded a multi-fold increase in the number and frequency of CHDHN episodes and the number of CWD episodes during 1984-2016 compared to the base period 1951-1983. More importantly, the incidence of compound events that coexisted with anomalous phases of sea surface temperatures registered a statistically significant spike in many locations. These changes in temperature-induced extremes pose an exceptional public health threat that can increase morbidity and mortality, disproportionately affecting vulnerable sections of Tamil Nadu’s populace engaged in outdoor work.

Anomalous Concentration of Uranium in Groundwater in Parts of Salem District, Central Tamil Nadu, India

Anomalous concentration of Uranium in groundwater has been identified around Virakkal, Veerapanpalayam, Pakkanadu, Erithottam, Kammampatti, Kumarappalyam, Idappadiand Moolakkadu areas in parts of Salem district, Tamil Nadu. In this study, an area of 970 sq. km from Mettur in the north to Kumarapalayam in the south parallel to the Koratti shear zone has been examined for uranium content in groundwater. Systematic sampling of groundwater (n=78) from bore well, open well and hand pump have been collected. The samples were analysed for uranium concentration using LED Fluorimeter. Analysis resulted higher concentration of uranium along the southern extension of Koratti Shear Zone where the emplacement of younger granites, syenite and carbonatites has been reported. These lithounits might have played a vital role in the contribution of uranium to the groundwater. Based on the result, two areas have been identified such as North Block and South Block for detailed investigation.58 systematic samples from North block and 52 samples from South block have been collected and analysed. Uranium values assayed in these areas are many times higher than the prescribed limit of World Health organisation and Atomic Energy Regulatory Board of 30ppb and 60ppb respectively. In northern block, among 58 samples 18 samples were assayed higher than 30ppb in which the samples from Veerappanpalayam assayed upto 545.81 ppb. Apart from Veerappanpalayam, many areas such as Mosakumarapalayam (273.90), Arasiramani (250.49ppb), Vellarivalli (131.32ppb), Kodarapalayam (106.52ppb), Savuthanur (174.79ppb), Veerapanpalayam-2 (373.43ppb) and Kotamppalayam (100ppb) were assayed more than 100ppb. Similarly, in the southern block, 52 samples were assayed in which 15 samples were higher than the prescribed limit in which Kuppampatti analyzed 402.29ppb, Virakkal and Thannikuttampatti assayed more than 100ppb. Among the total samples (n=188), 28% of samples were falling under non-potable category. The Present study has spatially brought to light significant areas where groundwater enriched by uranium concentration. It is also provided indirect evidences for uranium exploration in the study area.

A Study on Diabetes and Parkinson’s Disease in a Tertiary Care Centre at Central Tamilnadu

A Study on Diabetes and Parkinson’s Disease in a Tertiary Care Centre at Central Tamilnadu

Seasonal changes in groundwater quality deterioration and chemometric analysis of pollution source identification in South India.

Hydrogeochemical understanding of groundwater is essential for the effective management of groundwater. This study has been carried out to have concrete data for the seasonal variations in hydrogeochemistry of groundwater in central Tamilnadu forming a complex geological terrain with a varied lithology. A total of 244 groundwater samples were collected during four different seasons, viz, southwest monsoon (SWM), summer (SUM), postmonsoon (POM), and northeast monsoon (NEM) from bore wells. The physical parameters such as pH, temperature, TDS, ORP, humidity, and electrical conductivity (EC) were measured insitu, whereas major ions were analyzed in the lab adopting standard procedures. Overall, higher EC and NO3 values were observed and exceeded the WHO permissible limit irrespective of seasons, except for NO3 in SWM. Na and HCO3 are the dominant cation and anion in the groundwater irrespective of seasons. The highest average values of Na (65.06mgL-1) and HCO3 (350.75mgL-1) were noted during SWM. Statistical analysis was carried out to elucidate the hydrogeochemistry of the region. Initially, to understand the ionic relationship, correlation matrix was used followed by factor analysis for determination of major geochemical control and later factor scores were derived to understand the regional representations. An attempt hasalso been made to identify the samples influenced by multiple geochemical processes and to understand their spatial variation in the study period. Correlation of geochemical parameters reveals a excellent positive correlation between Ca and NO3 in SUM, SWM, and NEM due to the dominant of anthropogenic sources and minor influence of weathering process. Strongly loaded factor scores are found to be mostly in the following order POM > NEM > SWM > SUM. Principal component analysis of different seasons indicates the interplay of natural weathering and anthropogenic factors. Overall, the predominant geochemical processes in this region, irrespective of seasons are weatheringand, ion exchange and anthropogenic activities.

A Study on Etiological Profile of Non-Compressive Myelopathies in a Tertiary Care Hospital in Central Tamilnadu

A Study on Etiological Profile of Non-Compressive Myelopathies in a Tertiary Care Hospital in Central Tamilnadu

Clinical Profile and Risk Factors of Massive Middle Cerebral Artery Infarction in a Tertiary Care Centre in Central Tamilnadu

Clinical Profile and Risk Factors of Massive Middle Cerebral Artery Infarction in a Tertiary Care Centre in Central Tamilnadu

An interpretation of wave refraction and its influence on foreshore sediment distribution

To analyze the grain size and depositional environment of the foreshore sediments, a study was undertaken on wave refraction along the wide sandy beaches of central Tamil Nadu coast. The nearshore waves approach the coast at 45° during the northeast (NE) monsoon, at 135° during the southwest (SW) monsoon and at 90° during the non-monsoon or fair-weather period with a predominant wave period of 8 and 10 s. A computer based wave refraction pattern is constructed to evaluate the trajectories of shoreward propagating waves along the coast in different seasons. The convergent wave rays during NE monsoon, leads to high energy wave condition which conveys a continuous erosion at foreshore region while divergent and inept condition of rays during the SW and non-monsoon, leads to moderate and less energy waves that clearly demarcates the rebuilt beach sediments through littoral sediment transport. The role of wave refraction in foreshore deposits was understood by grain size and depositional environment analysis. The presence of fine grains with the mixed population, during the NE monsoon reveals that the high energy wave condition and sediments were derived from beach and river environment. Conversely, the presence of medium grains with uniform population, during SW and non-monsoon attested less turbulence and sediments were derived from prolong propagation of onshore-offshore wave process. These upshots are apparently correlated with the in situ beach condition. On the whole, from this study it is understood that beaches underwent erosion during the NE monsoon and restored its original condition during the SW and non-monsoon seasons that exposed the stability of the beach and nearshore condition.

Technical efficiency of banana production in central TamilNadu

Technical efficiency of banana production in central TamilNadu

Economic appraisal of different varieties of banana plantations in Central TamilNadu

Economic appraisal of different varieties of banana plantations in Central TamilNadu

Morphometric analysis of watershed using remote sensing and GIS—a case study of Nanganji River Basin in Tamil Nadu, India

Morphometric analysis of a river basin is essential to identify and assess seasonal changes in drainage basin characteristics, understand the groundwater potential, and address issues related to management of soil erosion due to flash floods during the high flows. Nanganji River Basin is one of the least studied seasonal river basins in India which carry substantial flows during the monsoon period. In this study, morphometry of Nanganji River Basin, located in the central Tamil Nadu prairies, has been studied using remote sensing and GIS. The interrelationship between the various morphometric factors of the basin has been studied using a correlation matrix. Factor analysis has been applied to group the individual morphometric parameters into a smaller number of factors. Further, these factors have been studied in relation to the sub-basins to understand the existing relation between the factors and the sub-basins. Finally, the study identifies environmental issues of the Nanganji River Basin mostly related to the river flow regime which widens significantly during the monsoon months.

Afterword: Gendering Caste: Honor, Patriarchy and Violence

Introduction The central significance of gender to the operation of caste was vividly highlighted for me during fieldwork on Dalit politics and mobilization in 2012. I visited the offices of the Communist Party of India (Marxist) (CPM) in Madurai (central Tamil Nadu) to interview the local leader Vikraman. He detailed the work of the Tamil Nadu Untouchability Eradication Front, which has documented the many and varied forms of untouchability practiced in contemporary Tamil Nadu. One example c...