Impact of industrial effluents on groundwater around Pali city, Rajasthan using field and satellite data

Groundwater pollution due to industrial effluents from textile units around Pali city area is the major concern to the local villagers and the district administration. Indiscriminate discharge of these effluents in the past two decades caused severe damage to the agricultural land and groundwater resources within 3 km buffer zone of the Bandi river. Remote Sensing and GIS techniques are found to be better tools in assessing the damage in agricultural crops during 1997 and 2006 with the help of high resolution satellite images. Groundwater fluctuation trend with annual rainfall pattern during 1985 and 2005 indicate good recharge in the study area. Detailed analysis of groundwater quality parameters (TDS, Cl and SO₄) and heavy metals (Cu, Pb, Zn, Fe, Cd and Cr) for 1997–98 indicates maximum concentration around Chatelao village and Dholera Jagir in the downstream direction of Bandi river. However, temporal analysis of groundwater samples collected in January, 2009 shows marginal decrease in concentration of TDS, Cl, SO₄, Pb and Cu in both groundwater as well as river effluents. Slight improvement in water quality especially heavy metals in the last 12 years (1998–2009) may be attributed to the appropriate measures (treatment of wastewater and solid waste disposal) taken by the establishment of three Common Effluent Treatment Plants (CETP) in Pali city area. However, a few stringent actions may be taken to avoid direct discharge of the effluents into Bandi river.     

Taxonomy and affinity of Early Mesoproterozoic megascopic helically coiled and related fossils from the Rohtas Formation, the Vindhyan Supergroup, India

A well preserved assemblage of compressed, straight, circular to sinuously coiled megascopic and helical carbonaceous fossils and other varied megascopic morphoforms are known from the Early Mesoproterozoic Rohtas Formation, Semri Group within Vindhyan Supergroup exposed in Katni district of central India. These megascopic remains are preserved as impressions, compressions, partially mineralized remains, and/or epi-relief. Some of the forms are typical filamentous empty sheaths and others are trichomes, with cell like entities under various stages of degradation. This study, based on fresh collections and also of the topotype material of the helically coiled megascopic fossils, straight forms and related fossilized remains occurring as epi-relief from Katni indicate that the two morphotaxa are distinct entities and possibly appear to be prokaryotes. Grypania spiralis and Katnia singhii are most likely of cyanobacterial origin. Spirally coiled and circular fossils, with epi-relief, and which probably represents a tissue grade organism, are considered as Spiroichnus beerii Mathur, 1983. Linear sheet-like carbonaceous solitary form has been placed in the morphotaxon Proterotainia and described as P. katniensis n. sp. Certain rare circular, carbonaceous forms are considered as Chuaria sp. A few circular disc-like forms found in the assemblage are treated as dubiofossils.     

Record of carbonate preservation and the Mid‐Brunhes climatic shift from a seamount top with low sedimentation rates in the Central Indian Basin

In the present investigation, an age model of carbonate‐rich cores from a seamount top in the Central Indian Basin (CIB) was constructed using both isotopic (²³⁰Th_excess, AMS ¹⁴C, oxygen isotopes) and biostratigraphic methods. The chronologies using the two methods are in good agreement, yielding a record of the late Middle Pleistocene to the Pleistocene–Holocene transition (550 to 11.5 ka). The first appearance datum (FAD) of the radiolarian Buccinosphaera invaginata (180 ka) and coccolith Emiliania huxleyi (268 ka) and the last appearance datum (LAD) of the radiolarian Stylatractus universus (425 ka) were used. A monsoon‐induced productivity increase was inferred from carbonate, organic carbon and δ¹³C records in response to the Mid‐Brunhes Climatic Shift (MBCS), consistent with an increased global productivity. While the coccolith diversity increased, a decrease in coccolith productivity was found during the MBCS. At nearly the same time period, earlier records from the equatorial Indian Ocean, western Indian Ocean and eastern Africa have shown an increased productivity in response to the influence of westerlies and increased monsoon. The influence of easterlies from Australia and the intensification of aridity are evidenced by increased kaolinite content and clay‐sized sediments in response to the MBCS. An increased abundance of Globorotalia menardii and other resistant species beginning from marine isotope stage (MIS) 11 and the proliferation of coccolith Gephyrocapsa spp. indicate increased dissolution, which is consistent with the widespread global carbonate dissolution during this period. The relatively high carbonate dissolution during the transition period of MIS 3/2 and glacial to interglacial periods (MIS 6, 7 and 8) may be due to the enhanced flow of corrosive Antarctic Bottom Water (AABW) into the CIB.     

Dispersion Pattern of PGE and Ag in Chromiferous Ultramafic Suite of Rocks in Sukinda Valley,India

Potential chromite ore deposits of India are situated in Sukinda, Odisha, which may also be considered as a potential resource for platinum group elements (PGEs). This paper reports on PGE geochemistry in twenty six samples covering chromite ores, chromitites and associated ultramafic rocks of the Sukinda ultramafic complex. Platinum group element contents range from 213 to 487 ppb in the chromite ore body, from 63 to 538 ppb in rocks that have chromite dendrites or dissemination and from 38 to 389 ppb in associated olivine–peridotite, serpentinite, pyroxenite and brecciated rocks. The PGEs are divided into two sub‐groups: IPGE (Ir, Os, and Ru) and PPGE (Pd, Pt, and Rh) based on their chemical behaviour. The IPGE and PPGE in these three litho‐members show a contrasting relationship e.g. average IPGE content decreases from chromite to chromitite and associated rocks while PPGE increases in the same order. Appreciable Ag in chromitite (270–842 ppb) is recorded. Positive correlation between IPGE with Cr₂O₃ and with Al₂O₃ is observed while these are negatively correlated with MgO. Covariant relationships between Au and Mg in rocks devoid of chromite and between Ag and Fe in chromitite sample are observed. Chromite in all seams and some chromitite samples exhibit an IPGE‐enriched chondrite normalized pattern while PPGE are highly fractionated and show a steep negative slope, thereby indicating that PGE in the parental melt fractionates and IPGE‐compatible elements prefer to settle with chromite. The rocks devoid of chromite and rocks containing accessory chromite exhibit a nearly flat pattern in chondrite‐normalized PGE plots and this suggests a limited fractionation of PGE in these rocks. Variation in the distribution pattern of PGE and Ag in three typical litho‐members of the Sukinda Valley may be related to multiple intrusion of ultramafic magma, containing variable volume percentage of chromite.     

Modelling forest resilience in Hindu Kush Himalaya using geoinformation

Resilience is the capacity of an ecosystem to absorb disturbance and undergo change while maintaining its essential structure, functions, identity and feedbacks. The forests of the Hindu Kush Himalayan (HKH) region are vulnerable to both natural and anthropogenic changes, and the forest land conversion and degradation. Using satellite-derived tree canopy cover percent data and precipitation as the explaining variable, we studied the forest cover resilience in a geospatial framework employing the logistic regression and polynomial equation fitting. Out of the \(4.3\,\hbox {million km}^{2}\) geographical areas, \(873{,}650\,\hbox {km}^{2}\) (20.20%) was under the forest in 2000 and experienced loss of \(11{,}250\,\hbox {km}^{2}\) during 2000–2010. We could model the forest cover and treeless areas fairly than the scrub and grassland owing to the variation in precipitation pattern. The majority of the forest cover (59.3%) has been estimated to have less resilience owing to the receipt of <1650 mm of total annual precipitation, whereas only \(375\,\hbox {km}^{2}\) forest area could change to scrub that shows the least resilience. About 94.4% of treeless areas were estimated to be stable, while only 1% \((25{,}200\,\hbox {km}^{2})\) area could accommodate the grassland. The resilient forest areas estimated and observed, owing to the mapping and modelling protocols used in this study, shall be useful in conservation planning in the HKH region.     

Neotectonic activity of the Bomdila Fault in northeastern India from geomorphological evidences using remote sensing and GIS

One of the major geological structures across the Brahmaputra valley, which stretches from the Eastern Himalayas up to the Naga Hills, is the Bomdila Fault. Parts of the courses of the rivers – the Brahmaputra, Dhansiri (south-S), Bargang and many others – are aligned along this structure. The influence of this structure on the courses of these rivers has been studied in detail using topographic maps, satellite data and field evidences. The signatures obtained such as: (a) an unusually linear course of the lower part of the Dhansiri (S) river from Golaghat up to Dhansirimukh, (b) the abandonment of the westerly course of the earlier Dhansiri (S) river (flowing through Kaziranga) towards the present NW direction by avulsion, (c) knick bends in the MBT–MCT and Naga Thrust of Belt of Schuppen, (d) a linear 15 m high topographic scarp on the left bank of the Dhansiri (S) near Numaligarh and (e) an anomalous SE–NW trending course of the Brahmaputra from Dhansirimukh up to Hartamuli along with the parts of the rivers Buroi and Bargang on the north in the same trend infers the influence of a fault-type structure. Since all these linear segments of the rivers align along the NW–SE trending Bomdila Fault, it infers the influence of the later on the courses of these rivers. The neotectonic activity along this fault might have caused the linear high scarp and abandonment of earlier river courses.     

Impact of Rainfall Variability on River Hydrology: A Case Study of Southern Western Ghats,India

The Western Ghats plays a pivotal role in determining the hydrological and hydroclimatic regime of Peninsular India. The mountainous catchments of the Ghats are the primary contributors of flow in the rivers that sustains the life and agricultural productivity in the area. Although many studies have been conducted in the past decades to understand long term trends in the meteorological and hydrological variables of major river basins, not much attention have been made to unfold the relationship existing among rainfall and river hydrology of natural drainages on either side of the Western Ghats which host one of the unique biodiversity hotspots across the world. Therefore, an attempt has been made in this paper to examine the short term (last three decades) changes in the rainfall pattern and its influence on the hydrological characteristics of some of the important rivers draining the southern Western Ghats as a case study. The short term, annual and seasonal trends in the rainfall, and its variability and discharge were analyzed using Mann-Kendall test and Sen’s estimator of slope. The study showed a decreasing trend in rainfall in the southwest monsoon while a reverse trend is noticed in northeast monsoon. Correspondingly, the discharge of the west and east flowing rivers also showed a declining trend in the southwest monsoon season. The runoff coefficient also followed the trends in the discharge. The runoff coefficient of the Periyar river showed a decreasing trend, whereas the Cauvery river exhibited an increasing trend. A high-resolution analysis of rainfall data revealed that the number of moderate rainfall events showed a decreasing trend throughout the southern Western Ghats, whereas the high intensity rainfall events showed an opposite trend. The decline in groundwater level in the areas which recorded an increase in high intensity rainfall events and decrease in moderate rainfall events showed that the groundwater recharge process is significantly affected by changes in the rainfall pattern of the area.     

Tectonics and thermal structure of western Satpura,India

Increased seismicity and occurrences of hot springs having surface temperature of 36–58 °C are observed in the central part of India (74–81° E, 20–25° N), where the NE trending Middle Proterozoic Aravalli Mobile Belt meets the ENE trending Satpura Mobile Belt. Earlier Deep Seismic Sounding (DSS) studies along Thuadara-Sendhwa-Sindad profile in the area has showed Mesozoic Sediments up to around 4 km depth covered by Deccan Trap and the Moho depth with a boundary velocity (P_n) of 8.2 km/s. In the present study, surface heat flow of 48 ± 4 mW m^?2 has been estimated based on P_n velocity, which agrees with the value of heat flow of 52 ± 4 mW m^?2 based on Curie point isotherms estimates. The calculated temperature-depth profile shows temperature of 80–120 °C at the basement, which is equivalent to oil window temperature in Mesozoic sediments and around 570–635 °C at Moho depth of 38–43 km and the thermal lithosphere is about 110 km thick, which is comparatively higher than those of adjoining regions. The present study reveals the brittle–ductile transition zone at 14–41 km depth (temperature around 250–600 °C) where earthquake nucleation takes place.     

Transport and mobilization of multiwall carbon nanotubes in quartz sand under varying saturation

In this study, a series of sand packed columns were used to investigate the mobility of multiwall carbon nanotubes (MWCNTs) in unsaturated porous media under unfavorable conditions for deposition. The flow through column experiments were designed to assess water content, flow rate, and grain size effect on the mobility of MWCNTs. It was found that variation in water content had no significant effect on retention of MWCNTs until it was lowered to 16 % effective saturation. Thick water films, high flow rate, and repulsive forces between MWCNTs and porous media made MWCNTs highly mobile. Different porous media grain sizes (D ₅₀ = 150–300 μm) were used in this study. The mobility of MWCNTs slightly decreased in finer grain sands, which was deemed to be an effect of increase in surface area and the number of depositional sites, in combination with low-pore water velocity. However, physical straining was not observed in selected fine-grain sands and aspect ratio of MWCNTs had low impact on mobility. Variations in pore-water velocity were produced by both changes in water saturation and in flow rate. At high pore-water velocities, the MWCNTs were generally mobile. However, for the combination of low-pore water velocity with either low water saturation or small grain size, some retention of MWCNTs was observed. Hence, low velocity in combination with flow through smaller pores increased MWCNT deposition.     

Rapid flash flood calamity in Chamoli,Uttarakhand region during Feb 2021: an analysis based on satellite data

Natural Hazards - The present study investigates the accelerating factors for extreme flash flood at Chamoli district of Uttarakhand on 7 February 2021. The Sentinel-2A and 2B satellite data have...