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The present work was carried out to evaluate subsurface water quality for drinking purposes in the coastal region of Andhra Pradesh, India. The samples were collected from 80 locations covering in pre-monsoon season (PRM) and post-monsoon season (POM) during 2018–2019. The groundwater mainly consists of Na-Mg-Cl-HCO3and Na-Cl-HCO3type explaining the influence of seawater intrusion, marine sediments, and leaching of minerals in clay horizons. The result of principal component analysis (PCA) revealed Na+and Cl−have positive loads on both PC 1 and PC 2 corroborating reverse ion exchange and the anthropogenic activities. Evaporation dominance and dissolved carbonates of clay soils in the groundwater are indicated by Gibbs plots. PCA scores were taken into consideration in developing a groundwater quality index (GWQI) to classify water quality as excellent to good (4%), poor to very poor (92% in PRM and 70% in POM), and unfit (4% in PRM and 30% in POM) for drinking. Geospatial techniques have been used in preparing spatial and temporal distribution maps for various water quality parameters. The integrated approach adopted in the study are a cost-effective and time saving tool involved in assessing environmental problems more precisely. This study is expected to provide reliable information for stakeholders in understanding various types of pollutants in groundwater chemistry.

A correlation of the morphology of the Krishna-Godavari twin delta region with the tectonic framework of its basement along the east coast of India revealed that the Kolleru Lake in the inter-delta region is situated over a basement graben known as Gudivada Sub-basin, while the vast mudflat to the south of the lake coincides with the Bantumilli Sub-basin. The 8-km-wide beach ridge complex that separates the Kolleru and the southern mudflat largely coincides with the Kaja-Kaikaluru Ridge (horst) that lies in between the Gudivada and Bantumilli Sub-basins (grabens). The anomalous landward meandering of the Vasishta and Vainateyam distributaries close to the coastline and the three-fold widening during the past four decades of the Nilarevu estuary in the Godavari delta are in line with the Matyapuri-Palakollu Fault. Similarly, the 70-km-long straight segment of the delta-front coast between the Gautami and Vasishta distributary mouths in the Godavari delta, which is rather anomalous for a prograding delta, coincides with the landward boundary of the Ravva offshore sub-basin. Swerving of the Krishna River course throughout its deltaic reaches and the clock-wise bending of the active Krishna delta lobe into the Nizampatnam offshore sub-basin appear to be associated with the Krishna Cross Trend fault. Furthermore, the elongated nature of the Krishna delta and its visibly greater seaward bulge than its bigger neighbour (Godavari delta) in spite of the fact that the latter receives higher sediment loads and water discharges, might also be due to tectonic influence. Although the connection between the surface morphology and basement framework is hard to establish for want of detailed shallow subsurface data, the landform anomalies point to the possible influence of neotectonics in shaping the morphologies of the Krishna-Godavari deltas.

The kinetics of oxidation of DAA by Ce(IV) in dilute sulphuric acid medium has been studied and the reaction was found to obey a second order rate law. This DAA — Ce(IV) redox system has been used for the polymerization of acrylonitrile and the rate of polymerization was found to be proportional to[Ce(IV)]0.5, [DAA]0.5 and [M]1.5. Based on these results a probable mechanism for initiation and termination has been proposed. The chain lengths of the polymers were found to increase with [M] and decrease with both [Ce(IV)] and [DAA].

A comprehensive rock magnetic and absolute archaeointensity (AI) investigation was carried out on baked bricks from the east coast of India with an aim to obtain a set of well-defined palaeointensity (PI) data. The new PI data from India comprise a significant first step to improve the regional intensity reference curve, which can be used as reliable dating tool mainly for archaeomagnetic material. Standard Thellier-Coe experiments were applied on 12 independent brick samples collected from a Buddhist monument at Adurru in the Godavari delta and a Medieval Fort at Kolleti Kota site situated on an island in the Kolleru Lake. The samples thus collected represent two different archaeological periods, one around the 3rd century BCE and the other between the 4th and 7th centuries CE respectively. The data obtained from thermal demagnetization of Saturation Isothermal Remanent Magnetization (SIRM), temperature dependent magnetic susceptibility (χ–T), Isothermal Remanent Magnetization (IRM) acquisition curves, and hysteresis measurements showed that the primary carriers of Natural Remanent Magnetization (NRM) are fine-grained Pseudo-Single Domain (PSD) (Stable Single Domain (SSD) + Superparamagnetic (SP)) titanomagnetite with various titanium contents. This implies that the samples had significant stable Thermoremanent Magnetization (TRM), and, therefore, good candidates for PI analysis. Strict selection and quality-control criteria for detecting magnetomineralogical alteration and intensity data corrected for anisotropy and the cooling rate effects on TRM acquisition, offer high quality PI determinations with respect to the previous available data that missed such corrections.