M. Suresh Gandhi

Trace element concentration in surface sediments of Palk Strait, southeast coast of Tamil Nadu, India

The present work was carried to decipher the trace element accumulation in surface sediments of Palk Strait, southeast coast of Tamil Nadu, India. The elemental concentration and correlation results suggest that fine fractions with CaCO3 content followed by organic matter (OM) of the surface sediments control the trace element accumulation in the study area. In addition, Fe and Mn concentration is chiefly contributed from riverine process and controlled by the mangrove ecosystem. The other elements are derived into marine environment through confluence of untreated industrial pollutants into the river system. The EF result shows that the studied marine sediments are enriched by Ni, Mn, Cu, Pb, Cd, Cr, followed by Zn. The order of the pollution intensity with respect to geo-accumulation index suggests the following ascending order: Ni>Mn>Fe>Cu>Pb>Cd>Cr>Zn. Pollution Load Index (PLI) values reveal that all the samples are falling under moderately to unpolluted category.

Coastal Placer Deposits of Central Tamil Nadu, India

ABSTRACT Placer mineral exploration has been undertaken along the beach of Central Tamil Nadu coast from Pondicherry to Vedaranyam. On the basis of the drainage network, geomorphology, and the coastal environment, the study area has been grouped into three sectors, North, Central, and South. Heavy mineral by Wt% shows a slightly higher abundance in the Northern sector, an enrichment of opaques in the Central sector from stations between Poompuhar and Karaikal, and a total depletion in the Southern sector. An abundance of heavies in the Northern sector is considered to be the result of a higher wave energy, and the cymatogenic downwarping of the basin during the present transgression. An enrichment of heavies in the Central sector from Poompuhar to Karaikal is attributable to the reworking of the beach ridges, which were submerged during the present transgression, and to the role of density sorting. A depletion of heavies in the Southern sector is accounted for by the absence of a terrigenous supply and the prevalence of wave shadow conditions throughout the year. The nature of the heavy mineral assemblage reflects the derivation of sediments principally from khondalites, granites, metamorphic rocks and paleo-sediments. Factor analysis also supplements the predominant role of a density factor in the segregation of heavy minerals in the study area. A five-stage model is proposed for the formation of placer deposits in the study region. The present study has disclosed rich concentrations of ilmenites in the central sector between Poompuhar and Karaikal that can be commercially exploited.

Assessment of Heavy Metal Contamination in Marine Sediments of East Coast of Tamil Nadu Affected by Different Pollution Sources

The aim of this study was to determine the concentration of heavy metals in the sediments of Periyakalapet to Parangipettai coast, east coast of Tamil Nadu, by using energy-dispersive X-ray fluorescence (EDXRF) technique. The average heavy metal concentrations in the sediment samples were found in the order Al>Fe>Ca>Ti>K>Mg>Mn>Ba>V>Cr>Zn>La>Ni>Pb>Co>Cd>Cu. The average heavy metal concentrations were below the world crustal average. The degree of contamination by heavy metals was evaluated using pollution indices. The results of pollution indices revealed that titanium (Ti) and cadmium (Cd) were significantly enriched in sediments. Pearson correlation analysis was performed among heavy metal concentrations to know the existing relationship between them. Multivariate statistical technique was employed to identify the heavy metal pollution sources.

Heavy mineral distribution and geochemical studies of coastal sediments between Besant Nagar and Marakkanam, Tamil Nadu, India

Abstract The main objectives of the present study are to understand the heavy mineral distribution, trace elemental distribution and to study the variation, if any, between the grain size and trace elemental distribution within the beach. Totally 20 stations have been collected and weight percentage of heavy minerals are identified. In the present study area most of the sands are fine and medium grained, indicates beach environment and most of the grains are positively skewed. The study area contained a high percentage of orthopyroxene (hypersthene) and garnet, rounded and broken zircons inferred to have been derived from charnockites and granulite gneiss of the study area. Overall from the geochemistry studies, it is observed that the Ni and Cr are more dominant and higher concentration in Panayar (station no. 2), Mahabalipuram (station no. 6), Kalpakkam (Station no. 7) and Perunthuravu (station no. 8). The present study has clearly indicated the multiple roles of tectonically controlled coastal blocks and their geomorphological influence in redistributing the sediments with favourable NE–SW configuration and wave energy conditions must have contributed to the formation of heavy minerals in a particular zone.

Benthic foraminifera and geochemical studies with influence on pollution studies along the coast of Cuddalore, Tamil Nadu-ITS, India

Foraminifers, being sensitive to minute changes, either undergo morphological changes or even disappear from the area completely due to pollution or under unfavourable conditions. The characteristics of foraminifers to incorporate the signature of presence of pollutants are considered to be an effective tool for temporal pollution monitoring studies. Totally, 12 offshore samples (both sediment and water) were taken along a normal profile along the coast of Cuddalore for pollution studies. Apart from foraminiferal studies, geochemical studies of the sediments collected are also undertaken to correlate and substantiate the findings. The near-shore area has a higher concentration of trace elements. If these concentrations exceed or go below permissible limits, it is collateral for the marine community and for those who consume these marine resources. The concentration of trace elements like lead, zinc, manganese, copper, chromium and nickel was illustrated to give an idea of the trace element concentration of the study area. The sedimentological studies reveal the organic matter and calcium carbonate content of the samples, and the bottom water measurements reveal the temperature, salinity and dissolved oxygen of sample locations. These are used to determine whether the conditions prevailing could sustain life. The ratio of living to dead species is also determined and correlated with sedimentological and geochemical parameters. Pollution studies have given way to identify morphological abnormalities in the species mainly in Spiroloculina, Quinqueloculina, Elphidium, etc. but we could not find many effects among the faunal assemblages because of the nature of the sediments found in that area.

Recent benthic foraminifera and their distribution between Tuticorin and Tiruchendur, Gulf of Mannar, south-east coast of India

Foraminifera have been successful inhabitants of every aquatic environment from deep oceans to brackish water lagoons, estuaries and even rarely in freshwater streams, lakes, etc. In order to know their distribution in different offshore habitats, the present study has been undertaken between Tuticorin and Tiruchendur, wherein 31 bottom sediment and water samples were collected. Benthic foraminiferal taxa belonging to four suborders (Textulariina, Miliolina, Lagenina and Rotaliina), 14 superfamilies, 25 families, 45 genera and 66 species have been identified; three planktonic species (suborder Globigerinina) have also been identified. An increase in total foraminiferal distribution with depth has been observed, except off Tiruchendur. Living/dead ratios range from 1.57% to 10.02%, indicating a low to moderate rate of sedimentation in this region. Off Punnaikayal and Tiruchendur, the rate of sedimentation is more at greater depths; at other stations, however, it is higher at relatively shallower depths. Based on this study, it is concluded that fluctuations in the distribution of foraminifera are mainly controlled by coastal morphology, wave dynamics, bathymetry and environmental parameters.

Assessment of gamma radiation and associated radiation hazards in coastal sediments of south east coast of Tamilnadu, India with statistical approach

Gamma spectroscopy was performed to determine the concentrations of 226Ra, 232Th and 40K in sediment samples collected from Periyakalapet to Parangaipettai, East coast of Tamilnadu. The activity concentrations were determined by direct counting using a hyper pure germanium (HPGe) detector inter phased with a multi channel analyzer (MCA). The average activity concentrations of the corresponding nuclides were 30.81 Bq kg-1 for 226Ra, 85.67 Bq kg-1 for 232Th and 425.72 Bq kg-1 for 40K. The average activity concentration of 232Th and 40K are slightly higher and 226Ra is lower than world average values. The radiation hazard indices namely Radium Equivalent Activity (Raeq) Absorbed Gamma Dose Rate (DR), Annual Effective Dose Rate (HR), Representative Level Index (RLI), Annual Gonadal Dose Equivalent (AGDE), Internal Hazard Index (Hin) and External Hazard index (Hex) are calculated and compared with the previously reported data. The extracted values are comparable to the recommended values and they all fall within the safety limits. Hence harmful radiation effects are not posed to the public and tourists going to the beaches for recreation or to the fishermen involved in their activities in the area as a result of the natural radioactivity of sediments. Multivariate Statistical analyses were carried out between the parameters obtained from the radioactivity to know the existing relations and to study the spatial distribution of radionuclides.

Heavy Minerals and Granulometric Studies in Coastal Sediments from Keelakarai to Periyapattinam, Gulf of Mannar, East Coast of India

In this study, granulometric and heavy minerals analysis were carried out in coastal sediment samples from Keelakarai to Periyapattinam, Gulf of Mannar, east coast of India to examine the feasibility of energy conditions that had prevailed during the deposition and its respective heavy mineral assemblages. Out of 40 samples, the backshore area are fine grained, whereas the foreshore area is enriched with mixed grains ranging from coarse to medium grained in size in the alternate samples. Most of the samples were classified under moderately sorted and moderately well sorted in the backshore area, wherein at the foreshore it is poorly to moderately sorted in nature. Most of the sample falls under leptokurtic curve while few other locations fell under mesokurtic. Fine skewed nature is observed in the foreshore samples. Most of the samples are unimodal and few are bimodal. The unimodality at the location reflects the lack of sediment deposition by the rivers. The bimodality is ascribable due to the discharge of fine sediments from small rivers like Gondar and Vaippar. The presence of fine sediments is the reflection of depositional environment which is corroborated with the strong wave divergence that prevails in this region. The coarse grained nature in the foreshore might be due to the prevailing high-energy environment, where the wave is orthogonally converging. Individual heavy mineral weight percentage is analyzed and it varies from 5.5 to 31.55%. The lowest values were noticed in 9 samples, whereas the highest values were observed in the stations 5, 7, and 15 which receives more than 15% of heavies. Based on the Isodynamic separation studies it is observed that the magnetite and ilmenite were found more at 0.3 A. Further, from the textural analysis, it is clear that the area from Keelakarai to Periyapattinam is generally experiencing the depositional environment as evident from positive skewness with the exception of three locations which are undergoing erosion as evident from negative skewness. This study shows that in the field of placer deposit investigations, it is significant to correlate the techniques like granulometric, Frantz Isodynamic separator and bromoform separation.

Data on Heavy metal in coastal sediments from South East Coast of Tamilnadu, India using Energy Dispersive X-ray Fluorescence (EDXRF) Technique

This article contains the chemical and geographical data and figures for the chemical data in sediments of East Coast (Pattipulam to Dhevanampattinam) of Tamilnadu. The obtained data are related to the research article “Heavy Metal Assessment in Sediment Samples Collected From Pattipulam to Dhevanampattinam along the East Coast of Tamil Nadu Using EDXRF Technique” (Chandramohan et al., 2016) [1]. Chemical data are collected from Energy dispersive X-ray fluorescence spectrometer (EDXRF). Furthermore, the obtained chemical data describes it in more detail in the figures.