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Microplastic (MP) is a contaminant presently causing a significant environmental risk. The present study aims to extract, measure, and classify MP in sediment samples from two seasons (monsoon and summer) in Noyyal River, South India. Microplastic was separated from sediments using the Sediment Microplastic Isolation technique. Microplastics were detected in four forms: foams, films, fragments, and fibres. Dominant polymer types during monsoon are Polystyrene (29%), Polycarbonate (13%), Nylon (13%), and Ethylene Vinyl Acetate (13%). Throughout summer, Polystyrene (17%) was the prevalent polymer type, followed by Nylon (14%), Polycarbonate (11%), and Polyvinyl Chloride (9%). Scanning Electron Microscope (SEM) demonstrated that MPs exhibit diverse surface morphologies, including foamy, fibrous, and granular nature. It also shows tearing and fracturing of MPs and aging, indicating substantial summer degradation. Using Polymer Hazard Index (PHI) and Pollution Load Index (PLI), MP vulnerability in sediments indicates that despite lesser PLI, the MPs pose an extreme danger threat to the environment during the summer season compared to the monsoon. The study thus provides insight into the seasonal variation of MPs and their threat in Noyyal River sediments, which will aid in formulating guidelines for the minimization of MPs in river systems. [ABSTRACT FROM AUTHOR]

Study undertaken to find the structural arrangement of scales in similar coloured regions within butterfly wings of different species revealed their scale structure was architecturally different. The scales under scanning electron microscope showed difference among butterflies. Scales of Papilio polymnestor (Cramer) had high concentration of windows, Pareronica ceylanica (Felder) with beads and other species such as Talicada nyseus (Guerin Meneville), Atraphaneura aristolochiae (Fabricius), Junonia heirta (Fabricius), Neptis hordonia (Moore), Acrae violae (Fabricius) and Danus chrysippus (Linnaeus) had network and lamina. Tonality of colours showed differences in the arrangement of scales. [ABSTRACT FROM AUTHOR]

River sand samples have been collected from Ponnai river, Tamil Nadu, India for characterization of minerals and heavy metals by different spectroscopic techniques. Initially, the samples were subjected by Fourier Transform-Infra Red (FT-IR) spectroscopic technique and infra-red absorption bands values are observed in the range of 515–520, 695–700, 775–780 cm−1 which shows the presence of quartz in all the samples. Similarly, infra-red peaks were absorbed for feldspar, kaolinite, calcite, gibbsite and organic carbon and confirmed by X-Ray diffraction (XRD) technique. Additionally, zircon, aragonite, magnetite and kyanite minerals were identified in the samples using only the XRD method. The concentration of heavy metals such as Pb, Cr, Zn, Ni, Hg, As, Mn, Cu has been determined by flame atomic absorption spectrometry (FAAS). An average metal concentration measured in mg kg−1 were: Pb 0.12, As 0.15, Hg 0.13, Cu 2.80, Zn 10.15 Cr 12.70, Ni 2.86 and Mn 104.94 and hence found in the order of Mn > Cr > Zn > Ni > Cu > As > Hg > Pb. These average values do not exceed the world average value and hence potentially do not affect the quality of sand in the river. In addition to that, presences of heavy metals are confirmed by scanning electron microscope equipped with energy dispersive X-ray spectrometry (SEM/EDS) analysis. In order to understand the possible natural and anthropogenic sources of heavy metals, multivariate statistical techniques such as Pearson correlation, principal component and cluster analysis were performed. Results obtained from the statistical techniques were good agreement with each other. [ABSTRACT FROM AUTHOR]

Abstract: The systematic and scientific study of artifacts reflects technological development and civilizations during the past. The importance of pottery artifacts as indicators of the artistic and technological advances reached by the ancient culture is investigatedby a number of techniques. Spectroscopic studies have been performed on recently excavated archaeological pottery samples from Thiruverkadu, Tamilnadu, India. The clay mineral type and its structural deformation due to firing have been studied from their Fourier transform infrared (FT-IR) spectra. The maximum firing temperature attained during baring, firing conditions (open/reduced atmosphere) and iron mineral phase changes is well established. X-ray diffraction (XRD) is used to identify minerals in the potsherds. Further scanning electron microscope (SEM) studies on potsherds pave the way to microstructural analysis and trace the subsequent development of virtification stages, thereby firing temperature is being confirmed. The results obtained from the different techniques provide the information for understanding the technological conditions implemented for the production of pottery and are found to give useful information about the analytical composition of potteries. [Copyright &y& Elsevier]

Abstract: In the present study, fragmented pottery samples were collected from the recently excavated archaeological site named Salamankuppam near the famous Mahabalipuram in Chennai, Tamilnadu, India. An attempt was made to subject the samples to scanning electron microscope with energy dispersive spectrometer (SEM/EDS) and chemical analysis. Also porosimetry study was done. The result from the analysis provided the chemical composition of the potteries, the firing atmosphere and firing temperature achieved by the artisans at the time of manufacture. The results obtained from different analytical techniques provided information of the firing temperature of the pottery which lies in the range of 800°C–950°C in the oxidizing and reducing atmosphere. Mineral magnetic studies also were performed and proved that all samples were highly magnetically enhanced materials and paleointensity measurements by Thellier method yielded the field intensity value of 42.15±2.0μT. The age of the sample was around 150 BC. [ABSTRACT FROM AUTHOR]

Abstract: An attempt has been made in the present work to estimate the firing temperature of the archaeological pottery shreds excavated from the three archaeological sites namely Maligaimedu, Thiruverkadu and Palur in the state of Tamilnadu in INDIA. The lower limit of firing temperature of the Archaeological pottery shreds were estimated by refiring the samples to different temperatures and recording the corresponding FT-IR spectrum. The firing methods and conditions of firing were inferred from the characteristic absorption positions and the bands observed due to the presence of magnetite and hematite in the samples. In addition, the Scanning Electron Microscopic analysis were carried out to study the internal morphology, vitrification factor and the upper limit of the firing temperature of the potteries fired at the time of manufacture. [Copyright &y& Elsevier]

Cretaceous phosphorites from the onshore of Tamil Nadu have been investigated for their origin and compared with those in the offshore. Cretaceous phosphorites occur as light brown to yellowish brown or white nodules in Karai Shale of the Uttatur Group in the onshore Cauvery basin. Nodules exhibit phosphatic nucleus encrusted by a chalky shell of carbonate. The nucleus of the nodules consists of light and dark coloured laminae, phosphate peloids/coated grains and detrital particles interspersed between the laminae. Scanning electron microscope (SEM) studies reveal trapping and binding activity of microbial filaments. A mat structure with linearly arranged microbial filaments and hollow, cell-based coccoid cyanobacterial mat are present. Nodules contain abundant carbonate fluorapatite, followed by minor calcite, quartz and feldspar. The P2O5 content of the phosphorites ranges from 18 to 26%. The CaO/P2O5, Sr and F contents are higher than that of pure carbonate fluorapatite. Concentrations of Si, Al, K, Fe, and Ti are low. We suggest that the nuclei of the nodules represent phosphate clasts related to phosphate stromatolites formed at intertidal conditions. At high energy levels the microbial mats were disintegrated into phosphate clasts, coated with carbonate and then reworked into Karai Shale. On the other hand, Quaternary phosphorites occur as irregular to rounded, grey coloured phosphate clasts at water depths between 180 and 320m on the continental shelf of Tamil Nadu. They exhibit grain-supported texture. Despite Quaternary in age, they also resemble phosphate stromatolites of intertidal origin and reworked as phosphate clasts onto the shelf margin depressions. Benthic microbial mats probably supplied high phosphorus to the sediments. Availability of excess phosphorus seems to be a pre-requisite for the formation of phosphate stromatolites. [ABSTRACT FROM AUTHOR]