Corroboration of arsenic variation over the Indian Peninsula through standardized precipitation evapotranspiration indices and groundwater level fluctuations: Water quantity indicators for water quality prediction.

The contamination of groundwater with arsenic (As) as a result of geo-morphological and hydrogeochemical factors has been the subject of comprehensive research. However, there has been limited exploration of the spread of As under the influence of dynamic elements such as floods, droughts, and rapidly declining groundwater levels. Moreover, the utilization of rapidly changing natural forces, including hydroclimatic extremes and declining groundwater levels, in conjunction with standard climate indices such as the Standard Precipitation Index (SPI) and the Standard Precipitation Evapotranspiration Index (SPEI), for the purpose of elucidating As distribution has been minimal. Accordingly, this study specifically addresses these water quantity indicators, along with Gravity Recovery and Climate Experiment (GRACE) derived groundwater levels, to expound on As contamination at a Pan-Indian scale. Significant correlations were delineated between SPI, SPEI, GRACE-derived groundwater levels, and arsenic concentrations. Clustering results unveiled the grouping of states according to agro-climatic zones, thereby underscoring the similarities in water quantity dynamics across the Indian peninsula. The study additionally computed the Saturation Index (SI) for aragonite and deliberated on the potential future saturation of this pivotal mineral. The primary contribution of this study lies in the successful demonstration of a methodology for prognosticating As distribution based on available precipitation and climatic indices, groundwater withdrawal, and the geological prospects of agroclimatic zones. The insights derived from the analysis of SPI, GRACE data, and As concentrations furnish valuable input for water resource management vis-à-vis strategies for mitigating As contamination.

Indian and global scenarios of Bisphenol A distribution and its new analogues: Prevalence & probability exceedance.

We compare, the prevalence, fate, and sources of Bisphenol A both globally and in India. India has the highest concentration of BPA and Bisphenol S(BPS) in general, with vegetables, particularly corn, beans, strings, and raw or canned vegetables, being the largest contributors. Among all the matrices, bisphenols (BPs) are found in the highest concentration in food, followed by surface water, wastewater, and indoor dust. BPA, BPS, and BPF are the most commonly reported analogues in India, with BPA being the most dominant category used worldwide. The highest concentration of BPs is observed in Uttar Pradesh, Punjab and Haryana that are three major agricultural states of India however, there is still a research gap regarding the dietary exposure to BPs on an individual level. Environmentally detected BPA occurs in a range of below detection to 10636 ng. L-1, with significant geographic variations. Interestingly, the order of abundance in India was maximum for BPS, which is contrary to the global average, where BPA is observed as most abundant. BPS is found to be the most common BPs analogue in surface water worldwide, with limited removal efficiency by both naturally remediation and conventional treatment methods. Similar patterns were observed in the US-India and Japan-Korea regions in terms of their source-sink-prevalence-fate dynamics. The probability of exceeding safe concentrations of BPs is higher in India and Korea, suggesting that these countries are more vulnerable to high prevalence concentrations and the subsequent public health hazards.

Prevalence of pharmaceuticals and personal care products, microplastics and co-infecting microbes in the post-COVID-19 era and its implications on antimicrobial resistance and potential endocrine disruptive effects.

The COVID-19 (coronavirus disease 2019) pandemic's steady condition coupled with predominance of emerging contaminants in the environment and its synergistic implications in recent times has stoked interest in combating medical emergencies in this dynamic environment. In this context, high concentrations of pharmaceutical and personal care products (PPCPs), microplastics (MPs), antimicrobial resistance (AMR), and soaring coinfecting microbes, tied with potential endocrine disruptive (ED) are critical environmental concerns that requires a detailed documentation and analysis. During the pandemic, the identification, enumeration, and assessment of potential hazards of PPCPs and MPs and (used as anti-COVID-19 agents/applications) in aquatic habitats have been attempted globally. Albeit receding threats in the magnitude of COVID-19 infections, both these pollutants have still posed serious consequences to aquatic ecosystems and the very health and hygiene of the population in the vicinity. The surge in the contaminants post-COVID also renders them to be potent vectors to harbor and amplify AMR. Pertinently, the present work attempts to critically review such instances to understand the underlying mechanism, interactions swaying the current health of our environment during this post-COVID-19 era. During this juncture, although prevention of diseases, patient care, and self-hygiene have taken precedence, nevertheless antimicrobial stewardship (AMS) efforts have been overlooked. Unnecessary usage of PPCPs and plastics during the pandemic has resulted in increased emerging contaminants (i.e., active pharmaceutical ingredients and MPs) in various environmental matrices. It was also noticed that among COVID-19 patients, while the bacterial co-infection prevalence was 0.2-51%, the fungi, viral, protozoan and helminth were 0.3-49, 1-22, 2-15, 0.4-15% respectively, rendering them resistant to residual PPCPs. There are inevitable chances of ED effects from PPCPs and MPs applied previously, that could pose far-reaching health concerns. Furthermore, clinical and other experimental evidence for many newer compounds is very scarce and demands further research. Pro-active measures targeting effective waste management, evolved environmental policies aiding strict regulatory measures, and scientific research would be crucial in minimizing the impact and creating better preparedness towards such events among the masses fostering sustainability.

Demystifying the decadal shift in the extent of groundwater in the coastal aquifers of Gujarat, India: A case of reduced extent but increased magnitude of seawater intrusion.

Catastrophic increase in urbanisation and industrialisation along the coastal region leads to increased stress on groundwater reservoirs worldwide. As a growing economy, India faces extreme water crises due to rising water demand and escalating salinisation, specifically in the coastal districts. Therefore, this study shows the implication of a comprehensive modelling approach to assess the spatiotemporal changes in hydrogeochemical processes in the coastal aquifer of the Surat district. Using a multi-model assessment approach, the present study focuses on the decadal evolution in groundwater quality of the coastal aquifers of Surat, Gujarat. Fifty-one groundwater samples were collected for 2008, 2012, and 2018 to assess the spatio-temporal shift in groundwater quality. Piper diagram revealed a shift of hydrogeochemical facies from Mg2+-HCO3- type to Ca2+-Mg2+-Cl- type, indicating the increased salinisation over a decade. The result suggests that rock-water interaction, seawater intrusion mechanism, and anthropogenic activities (intensive agricultural activities and improper waste management) govern the hydrogeochemical processes in the coastal aquifer. A shift of dominance of carbonate weathering to silicate weathering with the dissolution of calcite, dolomite, and gypsum, changing the hydrogeochemistry, was observed over the last decades. This shift leads to the increasing hardness of groundwater. The enrichment of nutrients in groundwater during 2018 (NO3- = 2 to 85 mg. L-1) compared to 2008 (NO3- = 1 to 36 mg.L-1) indicates the increasing imprints of agricultural fertilizer application and human organic waste through sewage contamination on the coastal aquifer. The seawater mixing index model demonstrates that extent of seawater intrusion reduced in 2018 compared to 2012, but the magnitude increased near the coastal talukas (SMI =9.5). The present study helps to understand the increasing anthropogenic activities over a decade leading to increased salinisation and groundwater contamination in the aquifer system. This work can help local stakeholders, water resource managers, and the state government manage the groundwater resources and the future potential threat of aquifer contamination.

Application of remote sensing techniques to deal with scale aspects of GRACE data to quantify groundwater levels.

Groundwater has become an indispensable source of irrigation and drinking water. Industrial dependence on groundwater has also increased drastically. This has led to the rapid exploitation of groundwater. There is accelerating concern about the depletion of groundwater water levels and the deterioration of groundwater quality due to geogenic and anthropogenic causes. The availability of groundwater data is a huge concern, as it requires both time and capital. GRACE satellite project has become a very important tool for groundwater data access. The latest version of GRACE data provides terrestrial water storage, which is the sum of surface and groundwater. The present study details the method to access GRACE satellite data and prepare a spatial map for analysis. It also discusses how to handle data at different resolutions to quantify meaningful correlations. Further, groundwater data is correlated with nitrate data (both are at different grid resolutions) to throw light on the relationship between the important anthropogenic contaminant (nitrate) and groundwater levels. This provides insights into the linkage of quantity with quality. In brief, the important contributions of the paper are: • To provide the methodology to access GRCAE data and prepare spatial maps. • To handle the variables at different grid resolutions. • To correlate two GIS maps at different spatial resolutions.

Climate indices and hydrological extremes: Deciphering the best fit model.

The present work comprehensively reviews all the pertinent large-scale climate indices used to analyse the hydrological extremes in India; along with various non-linear models, which have utilized long-term past precipitation data, and global climate indices to produce forecasts at different temporal scales. We specifically enumerated various statistical operations that may provide better precision at modelling efficiency. Further, in the quest to discover the best-fit modelling technique for the Indian scenario, we compared various modelling techniques applied to decipher hydroclimatic tele-connections between extreme hydrological variables and the large-scale climate indices. Our analyses suggest that the global atmospheric phenomena have performed better than the traditional geospatial models pertaining to the accurate prediction of precipitation extremes for India. We also confirmed that the use of large-scale climate indices to predict the local scale hydrological dynamics had been steadily increasing owing to the advantage associated with it. We conclude that wavelet-based non-linear models are a better fit, and large-scale climate indices based hydrological extremes prediction is an essential requirement for deciphering the esoteric nature of the Indian monsoon. The present work aims to contribute towards efficient water resources management under the pre-text of Indian hydrological extremes, which will be crucial and critical day by day for boosting Indian rain-dependent agriculture, as well as water supply and security.

Isotopic and hydrogeochemical tracking of dissolved nutrient dynamics in the Brahmaputra River System: A source delineation perspective.

The Brahmaputra river system (BRS) produces the largest discharge in India, supplying water to more than 62 million inhabitants. The present study aims to quantify the environmental elements that affect the spatio-temporal variation of nutrients in the Brahmaputra river system (BRS). The association of physico-chemical characteristics of floodplain sediments with the distribution pattern of P during wet and dry periods in different depths were also studied. The seasonal variation suggest that the average dissolved inorganic nitrogen and dissolve inorganic phosphorus are found higher in monsoon while the average dissolve silica were higher in post-monsoon. The spatial variation of dissolve inorganic phosphate and nitrate concentration suggests both the nutrient are higher in upstream sites. The DiS concentrations tended to be higher in downstream. In 70% of the sampled tributaries, the average molar ratio for dissolved inorganic nitrogen/dissolved inorganic phosphorous (DIN/DIP) was greater than 16:1, which indicates phosphate limited biological productivity. In contrast, an average molar ratio of dissolved inorganic silica/DIN (DSi/DIN) of 3.8 ± 3.0 favoured diatom growth in those tributaries where DSi/DIN molar ratio was lower than 1, indicating eutrophication. The BRS transported 24.7, 5.93, and 312 × 104 tons/year-1 of DIN, PO4-P and SiO2-Si, respectively. The depth-wise variation of P-fraction during monsoon suggests that the authigenic phosphorus was most abundant followed by Fe-bound, exchangeable, detrital and organic. In the post-monsoon, Fe-bound P was found at a higher concentration followed by authigenic phosphorus. High nutrient concentrations with more δ18O depleted water implied precipitation being the major source of nutrients in the BRS.