Rare Earth Elements (REE) play an important role in deciphering the nature of source rock and identifying neotectonic activity; therefore, the present study focused on investigating the distribution of REE in Gomati River sediments and the impact of subsurface tectonism in the Ganga alluvial plain. Twenty-nine bedload sediments and four biotite samples were analysed by ICP-MS. The total REE concentrations range from 53.72 to 676.44 µg/g (average 186.04 µg/g), whereas cerium (Ce: 299.92 µg/g) is the most abundant REE in the Gomati river sediments. The highest REE value (676.44 µg/g) was observed in the middle segment, where the sand fraction was converted into the fine clay content due to upliftments of the subsurface Faizabad Ridge. The chondrite-normalization of the sediment samples shows that the light REE (LREE) enrichment and flat heavy REE (HREE) pattern are very similar to those of the Ganga River sediments in the Himalayan region. LREE comprised approximately 92

Nearly 500 million people in India's Ganga Alluvial Plain (GAP) depend on groundwater for drinking and irrigation. However, excessive extraction is depleting shallow aquifers, and increasing urbanization and agricultural demand are expected to intensify this stress. Seasonal variations and weather anomalies further exacerbate groundwater pressure. This study focuses on the Gomati River, a major groundwater-fed tributary of the Ganga in the GAP, to quantify the seasonal contributions of groundwater and rainfall to river flow. Time-series river water and groundwater samples were collected at Chandwak near Ghazipur, and rainwater at Lucknow, within the central GAP from June 2009 to June 2010. Stable isotopes of oxygen and hydrogen (518O, 5D) were analyzed, and 518O values were used as tracers in a newly developed, season-specific two-component geochemical mixing model employing a Monte Carlo framework. Results indicate average groundwater contributions of 62 f 11% (n = 9), 52 f 30% (n = 12), and 97 f 34% (n = 14) during the pre-monsoon (April-June), monsoon (July-October), and non-monsoon (November-March) seasons, respectively. The highest groundwater input (100 f 0.0%, n = 3) occurred in January, while the lowest (33 f 20%, n = 3) was in October. These results reveal pronounced seasonal variability in groundwater-surface water interactions, showing that the Gomati River is largely sustained by groundwater during dry months and demonstrating how monsoondriven hydroclimatic variability controls river flow in densely populated alluvial basins, with direct implications for sustainable groundwater management.

Riverine floods are severe natural disasters that cause massive socioeconomic and human losses, especially in densely populated regions of India. Accurate and trustworthy hydrological data are required to effectively mitigate these recurring catastrophes and for water resource management. The aim of this study is to identify the most suitable distribution model for the Gomati River, a tributary of the Ganga River system, based on the Lucknow-based gauging station. The annual peak discharge data from 1969 to 2011 were obtained from the Central Water Commission. The Mann-Kendall test shows a decrease in the magnitude of annual peak flood for the gauging station. In this analysis, the Log-Pearson type III, Gumbel Max, Lognormal, and Normal probability distribution models are used to estimate flood magnitudes for 2, 5, 10, 25, 50, 100, and 200-year return periods. Based on the Goodness-of-Fit tests, the Nash-Sutcliffe efficiency test and the root mean square error-observations standard deviation Ratio test, the Log-Pearson type III was found to be the best fit model. Estimated flood magnitudes for 2-, 5-, 10-, 25-, 50-, 100-, and 200-year return periods are 433.7, 805.6, 1147.9, 1715.1, 2253.3, 2907.0 and 3699.1 m³/s, respectively. These values are useful for designing safe hydraulic structures- such as dams and major bridges with a 100-year return period, and culverts or infrastructure with a 50-year return period- as well as for planning embankments, mapping flood hazard zones, and preserving riverine ecosystems in Lucknow.

In the northern part of India, the 900-km long Gomati River drains the central Ganga Alluvial Plain and transports its water and sediments to the Ganga River, one of the world’s largest fluvial system. The basin experiences a humid, sub-tropical climate characterised with the monsoon season of heavy precipitation. In the distal part of the river basin, hydrological data were collected from Maighat gauging station located at Chandwak for the present stage-discharge relationship study. With increasing fresh water demands from the ever growing human population in the Ganga Alluvial Plain, the Gomati River Basin has been facing acute crises of water resources and environmental degradation. Thus, the primary aim of the present study is (1) to analyse the stage-discharge relationship of the Gomati River, to detect its seasonal characteristics and (2) to elucidate the reliable stage-discharge rating curve for water resource management and environmental conservation. Findings of the present study indicated that the stage-discharge relationship displayed better correlation coefficient during the summer (R2=0.9881, N = 23) and the post-monsoon (R2=0.9166, N = 18) seasons than the winter (R2=0.8907, N = 27) and the monsoon (R2=0.8925, N = 36) seasons. The seasonal stage-discharge rating curves are discussed with particular reference to predict the accurate discharge variability for the low-gradient single-channel alluvial river. Based on detailed analysis and goodness-of-fit criteria, the linear stage-discharge rating curve was found to be the best for the Gomati River, and demonstrates good predictive accuracy (R2=0.9712, n = 66) with discharge condition of <250 m3/s. The application of results has a great importance due to practicality in water resource management in the densely populated and the highly agricultured alluvial plain of the Gomati River Basin. This is for the first time that the present hydrological rating curve study, based on the real time-series data, has been conducted so far. It is necessary to advance our understanding of the stage-discharge relationship in future studies under the climate change scenario.

Rare Earth Elements (REE) are the industrial "Vitamins" because of the high-technology based modern uses and their anthropogenic inputs in natural environment, this study mainly focused on Geogenic variability and anthropogenic imprints of Light Rare Earth Elements (LREE), in the recently deposited sediments of the Ganga Alluvial Plain. All the Sediment samples were analyzed by using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). LREE comprises about similar to 91% of total REE in the Gomati River Sediments and Cerium (300 mu g/g) was the most abundant LREE in the bedload sediments. Average LREE concentrations in bedload (170 mu g/g) and suspended load (184 mu g/g) sediments of the Gomati River were observed higher than the Average Sediments and the World Major Rivers Suspended Sediments and therefore, characterizing the LREE contamination in sediments. This contamination level assessed on the basis of Potential Ecological Risk Assessment (PERI), Contamination Factors (CF), Degree of Contamination (CD) and Geo-accumulation Index (Igeo), the trend of element contamination showed that Sm>La>Pr>Ce>Nd and PERI shows that LREE pose moderate to strong ecological risk, mostly by Pr and Sm in the study area. The spatial and temporal enrichment of LREE in sediments were observed in the Basin since last two decades. This paper mainly highlights the effects of socio-economic development linked modern high-tech processes on LREE contamination in the river sediments and cycling by the sub-tropical fluvial environment of southern Asia; where rivers supply similar to 30% of the global sediment input to the world's ocean.

This preliminary study highlights the vulnerability of water resources to mercury (Hg) contamination in the northern Indian plains, the global hotspot of atmospheric Hg emission. The total dissolved Hg in the river, lake and groundwater samples ranged from 5 to 1414 ng/L (n = 13). The dissolved Hg concentration increased by two orders of magnitude in the Gomati River due to the untreated effluent inputs from Lucknow urban center and by three fold in the Ganga River due to economic development during the last two decades. The dissolved Hg concentration in water resources was reported several folds high during the monsoon season and above the prescribed drinking water standards of World Health Organization. Atmospheric deposition was predominantly identified as source of Hg in the Karela Lake water (364 ng/L). The present study underscores the significance of monsoon-controlled anthroposphere-to-aquatic Hg transfer in the alluvial plain that acts as the caterer of 7% of the world's population.

This study explores 'Indicator Kriging' approach for assessment of health risk from exposure to trace elements concentration (delta(te)) in drinking water resources of the Central Ganga Alluvial Plain (CGAP), northern India. The estimates for delta(te) were generated using analysis of groundwater samples (n = 100) collected from the Lucknow monitoring area to map the predicted area of health risk. The predicted probability maps have reclassified into a unified scale to generate Trace Element Risk Index (TERI), which has further integrated with human population count data to generate Health Risk Index of Lucknow. The results indicate that the risk is potentially alarming in urban areas as relatively high delta(te) there are referring to the local (point) sources of contamination. Approximately 23.15% human population residing in about 69.77% of the total area is at moderate-to-high health risk probability. The findings of this study could help planning substantial remediation measures on long-term basis.

Rare earth elements (REE) are emerging as modern high-technology-related novel micro-contaminants in freshwater aquatic systems and are therefore attracting global attention due to their potential human health risks. The Gomati River (a tributary of the Ganga River) sediments were analyzed for REE concentrations to establish REE contamination and to identify biotite mica mineral as a geoindicator. Chondrite-normalized REE pattern of the river sediments and biotite mica mineral were similar and depict a strong light REE (LREE) enrichment and relatively flatter heavy REE (HREE). The maximum total REE (∑REE) concentration increased from 323 µg/g in 2012 to 673 µg/g in 2019. In the ∑REE, LREE contribution was > 80%, because of anthropogenic inputs, mainly petroleum-cracking catalysts and other high-technology-based products. The XRD analysis and the geochemical signature of the Gomati River sediments reveal the meaningful existence of biotite mica mineral. A distinct downstream REE enrichment pattern was identified in biotite from the mica-rich bedload sediments. The scanning electron microscopy-energy dispersive X-ray (SEM-EDX) mapping images of biotite also revealed the precipitation of Lanthanum, at the weathered edges, during the early stage of mineral weathering. Biotite mica was identified as a geoindicator for the assessment of REE contamination in the Gomati River and the Hindon River Basin of the Ganga Alluvial Plain. Future research is needed for the application of biotite mica mineral as a geoindicator that can help the environmental scientists to contribute more effectively to the interdisciplinary efforts in River Science.

We studied trace element mobility in the Gomati River (an alluvial tributary of the Ganga River in northern India) Basin by analyzing thirty-six time series water samples for their dissolved concentration of trace elements. Sodium-normalised elemental mobility indices vary over a wide range of the six orders of magnitude from 102 (Cd) to 10–4 (Zr). The highly mobile elements are B, As, Se, Sr, Mo and Cd. The moderately mobile elements are Al, P, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb and Pb. Titanium, Fe and Al, commonly assumed to be immobile at global level, are identified as moderately mobile elements. High trace element mobility in the Gomati River Basin had the geogenic factor associated with the chemical weathering of biotite mica mineral. For the river water quality assessment, the concentration of B, Cr, Cu, Zn, As and Pb lies below the desirable limits; while the concentration of Al, Fe and Se are above the WHO permissible limits of drinking water. At global scale, the Gomati River Basin contributes dissolved flux in significant proportions, namely Al (5.8%), Ti (4.4%), Fe (1.1%), Ni (1.2%), Se (21.5%) and Pb (1.7%) of total riverine flux. The proposed system model may provide means of qualify and quantify the environmental effects of trace elements mobility.

The continuous increase of the Sr-87/Sr-86 isotopic ratio in the seawater since last 40 Ma has been correlated with the rise of the Himalaya. The Ganga-Brahmputra Fluvial System drains the Himalaya along with the Ganga Alluvial Plain (GAP) and the northern Indian Craton regions. Under the humid subtropical climatic condition, the rivers of the alluvial plain contribute a significant (similar to 50%) in the water discharge. Previous studies have identified the Himalayan Rivers as a potential source for the steady increase of marine Sr budget; overlooking the contribution of alluvial rivers. We attempt to constrain the role of GAP as a source for Sr. The Gomati River, a 900 km-long tributary of the Ganga River, drains about 30,437 km(2) of the GAP with 7,390 x 10(6) m(3)/a water discharge and provides an ideal opportunity to understand the role of GAP in contribution of the global Sr-87 budget. A total of 44 river water, 33 groundwater, 6 rainwater, 3 lake water, and 13 alluvial sediment samples were analyzed for Sr-87/Sr-86 isotopic ratio to determine sources and mixing relationships of the rainwater, groundwater and river water within the GAP. In the Gomati River Basin, the average Sr isotopic ratio of the river water (0.7292) is higher than that of the average Ganga River water (0.7246) and much higher than that of world seawater (0.7119) and modern seawater (0.7092). The average Sr isotopic ratio of the shallow groundwater and rainwater was 0.7242 and 0.7139, respectively. The Gomati River drains the GAP having alluvial sediments with more radiogenic Sr isotopic ratio ranging from 0.7655 to 0.7244. Due to this, the river water displays strong seasonal variability with lower Sr isotopic ratio than groundwater during the monsoon season (0.7184). Our data indicate that the high water discharge contribution with reasonably higher Sr isotopic values from GAP river water makes it an important additional source of high radiogenic Sr in addition to the Himalayan source. The chemical weathering of alluvial sediments in GAP under the monsoon-controlled climatic condition is likely to make significant contributions to the evolution and budget of Sr isotope in the global sea.

Human health is “at risk” from exposure to sub-lethal elemental occurrences at a local and or regional scale. This is of global concern as good-quality drinking water is a basic need for our wellbeing. In the present study, the “probability kriging,” a geostatistical method that has been used to predict the risk magnitude of the areas where the probability of dissolved mercury concentration (dHg) is higher than the World Health Organization (WHO) permissible limit. The method was applied to geochemical data of dHg concentration in 100 drinking groundwater samples of Lucknow monitoring area (1222 km2) located within the Ganga Alluvial Plain, India. Threefold (high to extreme risk) and twofold (moderate risk) higher dHg concentration values than the WHO permissible limit were observed in all of the groundwater samples. The generated prediction map using the probability kriging method shows that the probability of exceedance of dHg is the highest in the northwestern part of the Lucknow monitoring area due to anthropogenic interferences. The hotspots with high to very high probability are potentially alarming in the urban sector where 32.4% of the total population is residing in 6.8% of the total area. Interpolation of local estimates results in an easily readable and communicable human health risk map. It may help to consider substantial remediation measures for managing drinking water resources of the Ganga Alluvial Plain, which is among the anthropogenic mercury emission–dominated regions of the world.

In the present study, continuity of coal seams was established in the area adjacent to the existing open cast coal mine at Talabira, Odisha situated close to Hirakud reservoir. Water tightness of the strata in the zone between the reservoir and the mine needs to be verified to prevent inundation by subterranean seepage and ensure safety. Multi electrode resistivity imaging technique was used to establish continuity of coal seams and verify water tightness. From the studies conducted in and around the mine along 13 profiles, coal seams with relatively high resistivity ranging from 500 to 1500 Ohm-m at depths varying from 10 to 31 m were delineated. The intervening strata between the reservoir and the open cast mine was found to be fairly tight without any significant zone susceptible to seepage.

Aluminium (Al), an environmentally abundant and immobile element, has been studied for its mobility in the Gomati River Basin, a part of the Ganga Alluvial Plain, northern India. The dissolved Al concentrations in the Gomati River water and the Lucknow groundwater range over three orders of magnitude, from 14 to 77,861 ppb. In the Gomati River water, Al is classified as a moderately mobile element. Nearly 19% of Lucknow groundwater samples and all the Gomati River water samples have Al values above the permissible limit (200 ppb) recommended by the World Health Organization. Systematic multi-disciplinary study is urgently required to understand the geological association of high Al mobility with human health in the Ganga Alluvial Plain, one of the densely populated regions of the world.

An investigation using environmental isotopes (δ18O and δD) was conducted to gain insight into the hydrological processes of the Ganga Alluvial Plain, northern India. River-water, shallow-groundwater and lake-water samples from the Gomati River Basin were analyzed. During the winter season, the δ18O and δD compositions of the Gomati River water ranged from −1.67 to −7.62 ‰ and −25.08 to −61.50 ‰, respectively. Deuterium excess values in the river water (+0.3 to −13 ‰) and the lake water (−20 ‰) indicate the significance of evaporation processes. Monthly variation of δ18O and δD values of the Gomati River water and the shallow groundwater follows a similar trend, with isotope-depleted peaks for δ18O and δD synchronized during the monsoon season. The isotopically depleted peak values of the river water (δ18O = −8.30 ‰ and δD = −57.10 ‰) can be used as a proxy record for the isotopic signature of the monsoon precipitation in the Ganga Alluvial Plain.

Though water and land pollution is very dangerous, air pollution has its own peculiarities, due to its transboundary dispersion of pollutants over the entire world. Air pollution is one of the serious problems faced by the people globally, especially in urban areas of developing countries like India. All these in turn lead to an increase in the air pollution levels and have adverse effects on the health of people and plants. Variations in biochemical parameters can be used as indicators of air pollution. Analysis data reveals that SPM and RSPM level were exponentially higher during winter season. The concentration of SO2 and NOx was greatly influenced by the automobile emission. Higher concentration of SO2 and NOx was found in commercial area as well as heavy traffic street area while NOx concentration was found higher than SO2. The content of chlorophyll in all the seasons in plants was higher in residential area than commercial area and heavy traffic street area. The average pheophytin content in plant leaves at all the location in winter was higher than chlorophyll content, which indicates the conversion of chlorophyll to pheophytin or reduced biosynthesis. Carotenoids content was maximum in monsoon and minimum in winter at all locations. Protein content was highest in both plants species in monsoon at all the locations, and the minimum reduction was found in both plants in winter at all the locations where the pollution level was comparatively high. POD activity was lowest in monsoon and highest in winter at all the locations. An increase in POD activity was observed at commercial and heavy traffic street location comparison to residential locations. This study observed the effect of air pollution on Peepal (Ficus religiosa) and Ashok (Polyalthia longifolia) as well as the suitability of selected plants as intermediate tolerant species to pollution.