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Freshwater lakes and sediments need to be monitored continuously for environmental assessment and geochemical explorations. Lake sediments are major sinks for organic matter and for all geochemical elements. In the present study, total organic matter (TOC), nitrogen (TN), and geochemical analysis of major oxides was carried out on Yercaud Lake surface sediments, located at a higher elevation in South India to infer sediment distribution pattern and source for organic matter. Particle size distribution of lake surface sediments suggests that the sediments are predominantly silty sand and sandy silt, poorly to very poorly sorted and symmetrically skewed. TOC/TN ratio (6.54–12.65) reveal that the organic matter (OM) is derived from the in situ lake sources particularly from the vascular plants and lake biota accumulation. Weathering indices that fall from [chemical index of alteration (CIA)] 88.59–93.08 values and A‐CN‐K plot reflects intense chemical weathering of the bedrock exposures in the source area, which was accelerated under warmer and humid climate conditions in the sub‐tropical regions. Al2O3/TiO2 ratio (6.94–26.62) indicates weathering particularly of the exposed charnockite rocks around the lake basin. [ABSTRACT FROM AUTHOR]

Optical bleaching of quartz may be incomplete due to decreased daylight intensity and narrower wavelength spectrum in water column, leading to age overestimation in young fluvial sediments. This hypothesis was tested on a low energy slack water deposits from Kaveri Basin in south India using the SAR protocol. Various tests suggest successful application of SAR on quartz from the study area despite low sensitivity and few numbers of bright grains. Partial bleaching can be ruled out if using SAR on small aliquots. The results suggest a uniform residual luminescence and a common sedimentary condition in this area. Due to partial bleaching, the lowest values of palaeodoses should be considered in preference to the average values. [ABSTRACT FROM AUTHOR]

Detailed description, analysis and interpretation of bio-mineral formations are fundamental to an understanding of their growth and origin. Study of morphology at the macro-level can be supplemented by examining the specimen under the microscope using thin sections prepared from undisturbed samples. Until recently the main emphasis in urological research on kidney stones (uroliths), has been to assist with biological interpretation using biological microscope supported by physical, X-ray diffraction (XRD), and scanning electron microscopy (SEM) studies. However, polarizing microscope studies have not been carried out to identify the mineral composition of the biologically formed uroliths. Biologically formed kidney stones offer an excellent material to study their microstructures and features under the optical microscope supplemented by SEM analyses to decipher and hierarchically understand its development of formation. In the present study thin sections of uroliths have been examined under a polarizing microscope (Nikon Eclipse E200) supported by SEM. [ABSTRACT FROM AUTHOR]