T. Ramkumar

Environmental magnetic and petroleum hydrocarbons records in sediment cores from the north east coast of Tamilnadu, Bay of Bengal, India

In this study, mineral magnetic properties and petroleum hydrocarbons were statistically analysed in four sediment cores (C1, A1, T1 and K1) from the north east coast of Tamilnadu, India to examine the feasibility of PHC concentrations assessment using magnetic susceptibility. The C1 and A1 cores reveal a clear horizon of increase in PHC above 35 and 50 cm respectively suggesting the excess anthropogenic loading occurred in the recent past. Magnetic properties which were enhanced in the upper part of the sediment cores were the result of ferrimagnetic minerals from anthropogenic sources. Factor analysis confirmed that the input of magnetic minerals and petroleum hydrocarbons in Chennai coastal sediments are derived from the same sources. The present study shows that instead of expensive and destructive PHC chemical methods, magnetic susceptibility is found to be a suitable, cheap and rapid method for detailed study of petroleum hydrocarbon contamination in marine sediments.

Evaluation of hydrogeochemical parameters and quality assessment of the groundwater in Kottur blocks, Tiruvarur district, Tamilnadu, India

A study was conducted to evaluate the water quality of Kottur block, Thiruvarur district, Tamilnadu. Groundwater samples from hand pumps and tube wells of 16 stations were analyzed during postmonsoon and premonsoon (2008) with the help of standard methods of APHA (1995). Dominance of cations are in the following order Na>Ca>K>Mg and Cl>SO4>HCO3>NO3 by anions in both the seasons. The analytical results shows higher concentration of total dissolved solids, electrical conductivity, sodium, chloride, and sulfate which indicate signs of deterioration but values of pH, calcium, magnesium, and nitrate are within permissible limit as per World Health Organization standards. From the Piper trilinear diagram, it is observed that the majority of groundwater samples are Na-Cl and Ca-Mg-SO4 facies clearly indicates seawater incursion. In Wilcox diagram, most of the samples fall in low to very high sodium hazard and low to very high salinity hazard indicates moderately suitable for agricultural activities. Kelly’s ratio and magnesium ratio indicates most of the samples fall in suitable for irrigation purpose.

Heavy metal distribution in surface sediments of the Tirumalairajan river estuary and the surrounding coastal area, east coast of India

Surface sediments collected at the Tirumalairajan river estuary and their surrounding coastal areas were analyzed for the bulk metal concentration. The sediments were collected from post- and premonsoon seasons. Dominances of heavy metals are in the following order: Fe > Mn > Zn > Pb > Cu in both seasons from estuary and coastal area. The results reveal that Fe, Mn, Cu, Pb, and Zn demonstrated an increased pattern from the estuary when compared to the coastal area. The heavy metal pattern of the sediments of the Tirumalairajan river estuary and its surrounding coastal area offered strong evidence that the coastal area was a major source of heavy metals to the estuarine region. For various metals, the contamination factor and geoaccumulation index (Igeo) have been calculated to assess the degree of pollution in sediments. The contamination factor and geoaccumulation index show that Zn, Pb, and Cu unpolluted to moderately pollute the sediments in estuarine part. This study shows the major sources of metal contamination in catchment and anthropogenic ones, such as agriculture runoff, discharge of industrial wastewater, and municipal sewage through the estuary and adjoining coastal area.

Application of remote sensing and GIS analysis for identifying groundwater potential zone in parts of Kodaikanal Taluk, South India

Groundwater potential zones were demarcated with the help of remote sensing and Geographic Information System (GIS) techniques. The study area is composed rocks of Archaean age and charnockite dominated over others. The parameters considered for identifying the groundwater potential zone of geology slope, drainage density, geomorphic units and lineament density were generated using the resource sat (IRS P6 LISS IV MX) data and survey of India (SOI) toposheets of scale 1:50000 and integrated them with an inverse distance weighted (IDW) model based on GIS data to identify the groundwater potential of the study area. Suitable weightage factors were assigned for each category of these parameters. For the various geomorphic units, weightage factors were assigned based on their capability to store ground-water. This procedure was repeated for all the other layers and resultant layers were reclassified. The reclassified layers were then combined to demarcate zones as very good, good, moderate, low, and poor. This groundwater potentiality information could be used for effective identification of suitable locations for extraction of potable water for rural populations.

Distribution of grain size, clay mineralogy and organic matter of surface sediments from Tirumalairajanar Estuary, Tamilnadu, east coast of India

The aim of this study is to understand the various sources and factors controlling the abundance and distribution of clay minerals, sand, silt, clay and organic matter of the surface sediments of Tirumalairajanar Estuary in two different seasons. The study was undertaken for two seasons, based on ten selected stations all along the estuary, mouth and freshwater zone. Furthermore, along the estuary region, clay and silt were observed and also at few stations in the upstream end. Organic matters in the sediments appeared to be the main mechanisms for the distribution of clay minerals in estuary indicated that the distributions of clay minerals were comparatively higher during postmonsoon than in premonsoon season. The clay mineral assemblage consists mainly of chlorite, kaolinite, montmorillonite, illite and very scarce gibbsite. The clay from the sediments has been separated and studied for mineral identification using X-ray diffraction analysis. The present study also reveals that sediment texture is one of the main controlling factors for the distribution of organic matter.

Identification and characterization of tsunami deposits off southeast coast of India from the 2004 Indian Ocean tsunami: Rock magnetic and geochemical approach.

The December 2004 Indian Ocean Tsunami (IOT) had a major impact on the geomorphology and sedimentology of the east coast of India. Estimation of the magnitude of the tsunami from its deposits is a challenging topic to be developed in studies on tsunami hazard assessment. Two core sediments (C1 and C2) from Nagapattinam, southeast coast of India were subjected to textural, mineral, geochemical and rock-magnetic measurements. In both cores, three zones (zone I, II and III) have been distinguished based on mineralogical, geochemical and magnetic data. Zone II is featured by peculiar rock-magnetic, textural, mineralogical and geochemical signatures in both sediment cores that we interpret to correspond to the 2004 IOT deposit. Textural, mineralogical, geochemical and rock-magnetic investigations showed that the tsunami deposit is featured by relative enrichment in sand, quartz, feldspar, carbonate, SiO 2, TiO 2, K 2O and CaO and by a depletion in clay and iron oxides. These results point to a dilution of reworked ferromagnetic particles into a huge volume of paramagnetic materials, similar to what has been described in other nearshore tsunami deposits (Font et al. 2010). Correlation analysis elucidated the relationships among the textural, mineral, geochemical and magnetic parameters, and suggests that most of the quartz-rich coarse sediments have been transported offshore by the tsunami wave. These results agreed well with the previously published numerical model of tsunami induced sediment transport off southeast coast of India and can be used for future comparative studies on tsunami deposits.

Variations in texture of beach sediments in the vicinity of the Tirumalairajanar river mouth of India

Abstract The distribution of grain size parameters along 11 km stretch of the beach sediments between Karikal and Nagore, reveals that the mean grain size exhibits a marked decreasing trend on either side of the mouth of the Tirumalairajanar River which flow from west to east. The sediments are mainly of medium to coarse grained, moderately sorted, near-symmetrical skewed to fine skewed and leptokurtic to mesokurtic in nature. Interrelationship of various parameters shows bimodal nature of sediments having dominance of medium to coarse sand. The major part of the sediment fall in a coarse to fine grained category (sand and silt). Based on the CM (Coarser one percentile value in micron) pattern, the sediment fall in rolling and suspension field. These factors includes the sediments discharged from the river mixes with offshore sediments and with the sediments eroded from a source rock. The effect of wave sorting, and the northward drifting of sediments by littoral current are understandable. Results indicate that the Tirumalairajanar River is the most important source for modern sediments in the study area. The agitation by waves is an important sorting mechanism in the study area, and the net sediment transport in the study area is northward. The findings are based on the grain sizes and also corroborated by short-term observations of the beach sediment dynamics and transport during the monsoon and summer seasons between Karaikal and Nagore region.

Environmental monitoring and assessment of heavy metals in surface sediments at Coleroon River Estuary in Tamil Nadu, India

The combined studies on grain size distribution, organic matter contents of sediments, sequential extraction and bulk concentration of heavy metals, statistical analysis, and ecological risk assessments were carried out to investigate the contamination sources and ecological risks of surface sediments at Coleroon River Estuary in Tamil Nadu, India. The sequential extraction of metals showed that a larger portion of the metals was associated with the residual phase and also in other fractions. The low concentrations of heavy metals were found in exchangeable and carbonate bounds (bioavailable phases). It revealed that sediments of Coleroon River Estuary were relatively unpolluted and were influenced mainly by natural sources. The observed order of bulk concentrations of heavy metals in the sediments was as follows: Fe > Mn > Zn > Cu > Pb > Cr > Ni > Co. Factor analyses represented that the enrichment of heavy metals was mostly resulted from lithogenic origins associated with anthropogenic sources. These sources were reconfirmed by cluster analysis. Risk assessment code (RAC) suggested that all metals were not harmful in monsoon season. However, Fe was in medium risk, and Mn and Cu were in low risk in summer. According to pollution load index (PLI) of sediments, all heavy metals were toxic. Cu might be related with adverse biological effects on the basis of sediment quality guidelines (SQG) in both seasons. These integrated approaches were very useful to identify the contamination sources and ecological risks of sediments in estuarine environment. It is expected that this research can give a useful information for the remediation of heavy metals in sediments.

Distribution of clay minerals in marine sediments off Chennai, Bay of Bengal, India: Indicators of sediment sources and transport processes

Abstract Clay mineralogy, texture size and statistical analyses were carried out on surface sediments from the continental shelf of Chennai, Bay of Bengal, India. The purpose of this study is to characterize the clay mineral distribution and its relation to the hydrodynamics off Chennai to identify the sources and transport pathways of the marine sediments. Characterization of clay minerals in coastal sediments by Fourier Transform Infrared (FTIR) spectroscopy has provided the association of quartz, feldspar, kaolinite, chlorite, illite and iron oxides (magnetite and hematite) derived from river catchments and coastal erosion. Kaolinite, chlorite, illite, iron oxides, and organic matter are the dominant minerals in Cooum, and Adayar region. High quartz and feldspar zones were identified in Marina, which are being confined the sand zone and paralleling the coast. The strong relationships among the wave energy density, sand, quartz and carbonate revealed that wave induced littoral drift system play a dominant role in transportation and deposition of sediments in the Chennai coast. The sediment texture and minerals data are in agreement well with the previous results of hydrodynamics and littoral drift models in this region. Multivariate statistical analyses (correlation, cluster and factor analyses) were carried out and obtained results suggested that clay minerals and organic matter are trapped in silt and clay particles, whereas quartz, feldspar and carbonate are associated with sand particles. Results of sediment sources and transport processes from this study will be useful to predict the fate of the pollutants released from land or the potential change in sediment delivery to coastal areas.

Assessment of groundwater quality using GIS and CCME WQI techniques: a case study of Thiruthuraipoondi city in Cauvery deltaic region, Tamil Nadu, India

AbstractThis research evaluated the groundwater quality of Thiruthuraipoondi city in the southern part of Tamil Nadu, India during summer and monsoon seasons in 2011. Eighteen groundwater samples were collected throughout Thiruthuraipoondi city and its surroundings. This case study represented that the combined analysis of ordinary kriging and CCME WQI in GIS was effective to evaluate the groundwater pollution sources, as well as for the spatial interpolation and assessment of groundwater quality. Groundwater samples evaluated by CCME WQI values belonged to good quality sectors in summer and monsoon, but to poor quality sectors at small patches of south and southeast directions in both seasons. Moreover, the higher concentration of Na and Cl was designated as irrigation waste and also seawater incursion. Based on the Piper plot, most of groundwater samples belong to Ca–Mg–Cl2 type and followed by Ca–Cl2 and Na–Cl types in summer season. In case of monsoon season, most of the groundwater samples dropped in...