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The temporal variations in electrical conductivity and the stable isotopes of water, δD and δ18O, were examined at Chhota Shigri Glacier, India, to understand water sources and flow paths to discha...

Groundwater chemistry of mining region of East Singhbhum district having complex contaminant sources were investigated based on heavy metals loads and other hydrochemical constituents. This study aimed to identify the degree of heavy metals exposure and their potential health risk to local population. The results of hydrochemical analysis showed that Na+, K+, and Ca2+ ions are the dominant cations in the groundwater, while HCO3−, F− and Cl− ions dominate the anionic part of the groundwater. The weathering process was considered the dominant factor to determine the major ionic composition in the study area. Compositional analysis for heavy metal has identified that groundwater of the study area is contaminated by Cd, Pb and Cr elements. Source of these metals have been identified as an anthropogenic inputs from mining activities and mineral processing units. Health risk analysis of individual heavy metal for chronic daily intake (CDI) and hazard quotient (HQ) was found in the order of Cr > As > Cd > Pb which is indicating high health risk for the population. In addition, Hazard Index (HI) analysis for heavy metals was found significantly high (>1) which is considered as a threat for human population because they have the tendency to accumulate in the body and cause variety of diseases like kidney problem, dysfunction of liver and renal cortex as well as cancer.

This investigation was carried out with the objective to understand the impacts of landfill leachate on groundwater quality. This study also explained the movement of trace metals in groundwater by using Visual MODFLOW/MT3D. It also delineates the various factors controlling the suitability of groundwater for domestic, agriculture and drinking purpose. The statistical assessment shows ~ 60.09% groundwater are in good condition, ~ 35.38% in poor condition and 4.53% in very poor condition. The spatial distributions of water quality index (LWQI) around landfills indicate landfills are in depleted condition. Hydrogeochemical classification indicates ~ 90.91% groundwater shows Ca–Na water-type cation facies and Cl− water-type anion facies. While 9.09% groundwater shows Ca–Na water-type cation facies and Cl−–SO42−–HCO3− anion hydrogeochemical facies. The mineral equilibrium diagram of groundwater has revealed that it is in equilibrium with silicate minerals and favors kaolinite formation. The saturation index indicates chrysotile (Mg3Si2O5(OH)4) (2.84), dolomite (CaMg(CO3)2) (0.45), ferric hydroxide (Fe(OH)3) (1.97–3.58), goethite (FeOOH) (7.86–9.47), hematite (Fe2O3) (17.73–20.95), hydroxyapatite (Ca5(PO4)3OH) (2.38–4.62), jarosite-K (KFe3(SO4)2(OH)6) (0.22–1.92), cerussite (PbCO3) (0.39), vivianite (Fe3(PO4)2·8H2O) (0.39) and willemite (Zn2SiO4) (0.35) are reactive mineral in groundwater aquifer of study area. The seasonal and temporal variation indicates anthropogenic influence. The calibration and validation of model show > 90% models correct with 95% confidence. The contaminant transport simulated in groundwater aquifer with the high accuracy (estimated standard error 0.049 m) for the large area (~ 300 km2). The trends of contour lines of trace metals concentration indicate; it will contaminate study area within few years of its release through the landfill.

Spatiotemporal variations of dissolved nutrients were studied along Gautami-Godavari mangrove ecosystem to delineate their sources and fate. Average values of nitrate (NO3-), dissolved silica (DSi) and phosphate (PO43-) is 2.09 mg/l, 12.7 mg/l and 0.16 mg/l in wet season and 0.47 mg/l, 6.96 mg/l and 0.29 mg/l in dry season respectively. In wet season river discharge has significant influence on NO3- and DSi. In dry season, NO3- and PO43- are controlled by groundwater discharge, benthic exchange and various in situ processes owing to sediment redox condition. Mixing model shows net addition of phosphate in Coringa mangroves (95%) and Lower estuary (13%) and net removal of nitrate (24.79%) in Coringa mangrove and in estuary (58.9%). Thus present mangrove acts as net source for phosphate and net sink for nitrate and DSi. Nutrient ratio shows seasonal switching between potential Phosphorus and Nitrogen limitation in wet and dry season respectively.

Comparative study of trace metals distribution in the surface sediment of Sundarban mangrove ecosystem in India and Bangladesh is one of the primary baseline study done so far. Trace metal distribution assessment covering lower salinity zone to higher salinity zone was done along Matla River (tidal river) in Indian side and freshwater zone to higher salinity zone along Passur River in Bangladesh side of Sundarban; representing anthropogenic influenced area, agricultural area, tourist site and pristine area. Trace metals distribution in the surface sediments of Sundarban mangrove ecosystem shows relatively higher value of trace metals, Co, Cr, Cu, Fe, Ni, Pb and Zn in Indian part when compared to Bangladesh. Enrichment factor shows the highest enrichment of Pb in both parts of Sundarban mangroves. Co, Cr, Cu, Pb and Zn show EF>1 indicates sediment contamination from anthropogenic activities. Cr, Ni and Pb were found to have moderate accumulation in geoaccumulation index with Fe showing high accumulation. Normalized data of trace metals shows 87.5% from Indian site and 80% of Bangladesh site as outlier, indicating anthropogenic influence. Out of total sampling site 50% of Indian and 40% of Bangladesh site show trace metal values enriched more than predicted value of trace metals indicating Indian part have more polluted sites than Bangladesh side of Sundarban, which is also confirmed by enrichment factor, I-geo and normalization values in both the sides.

Present study shows suspended sediment dynamics in the meltwater of Chhota Shigri glacier, Himachal Pradesh, India for different melt seasons during the period 2011-2014. Maximum suspended sediment concentration in the meltwater was found during the month of July 2011, 2012 and 2014 constituting to 55.2%, 48.3% and 46.9%, respectively. Whereas in 2013, maximum suspended sediment concentration was observed in August accounting for 46.1% of the total. On the other hand, maximum suspended sediment load was monitored in the month of July 2011, 2012 and 2014 constituting 59.5%, 63% and 55.7% of the total, respectively. Whereas in 2013, maximum suspended sediment load was observed in the month of August accounting for 49.8% of the total suspended sediment load. Annual distribution of suspended sediment concentration (SSC) and suspended sediment load (SSL) in the Chhota Shigri glacier shows higher value of SSC and SSL during the study period 2012 and 2013, which may be due to the presence of high glacial runoff and negative mass balance of the studied area during these time periods. Marked diurnal variation has been observed in the SSC of meltwater. Strong correlation was observed between SSC and SSL with discharge. On the other hand, SSC and SSL also showed strong exponential correlation with air temperature of the studied area. Sediment yield from the catchment of Chhota Shigri glacier is high during the peak melt season (July and August) and low during the late melt season (September and October). The average value of erosion rate for Chhota Shigri glacier basin during the study period 2011-2014 was calculated to be 1.1 mm/yr, which is lower than the average erosion rate of other Himalayan glaciers such as Rakiot, Chorabari and Gangotri glaciers, which may be caused by its geological setting containing high erosion resistant rocks such as granite, granite gneiss and porphyritic granite.

In this study, glacier ice thickness distribution and storage volume has been modelled for two glaciers viz., Vestre Broggerbreen and Feiringbreen situated across the Kongsfjorden around Ny-Alesund in Svalbard. These two high Arctic glaciers are being monitored through the ongoing efforts of the Indian Arctic Program. Here, the capability of a glacier specific shape factor parametrization approach was evaluated when paired with a parsimonoious, simple stress-driven, slope-dependent ice thickness estimation model called Glacier bed Topography2_Indian Institute of Technology Bombay version (GlabTop2_IITB). The modelled average thickness of ice for Vestre Broggerbreen and Feiringbreen Glaciers was 59 m and 92 m respectively during the study period. The obtained ice thickness estimates were found to be reliable when compared with the recent field estimates obtained through a Ground Penetrating Radar (GPR) survey. Moreover, the modelled results of both the glaciers were in good agreement with the consensus estimates of ice thickness reported in a recent study. The obtained results suggest that the modelling approach presented here can be an alternative to complex models, which requires lot of other data such as surface mass balance, surface velocity etc. Based on the modelled ice thickness distribution pertained to the year 2015, the total volume of the glacier-stored ice estimated for Vestre Broggerbreen Glacier and Freingbreen Glacier was 0.29 ± 0.04 km3and 0.65 ± 0.09 km3, respectively.

The present study aims at the assessment of environmental quality of the most polluted stretch of river Yamuna along the megacity of Delhi. The study was conducted in order to examine toxicity and health hazards associated with persistent pollutants present in the fluvial ecosystem. Eighty four sediment and 56 vegetable samples from same locations were collected from the Delhi segment of river Yamuna flood plain in order to examine 20 organochlorine pesticides (OCPs) and 9 heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn). Both the organic and inorganic groups of persistent toxic substances were monitored and analysed for the extent of eco-toxicological as well as dietary health risks posed to the local population. Eco-toxicological assessment was done based on sediment quality guidelines, enrichment factor, geo-accumulation index, degree of contamination and Pollution Load Index. The dietary-risk was assessed with the help of translocation factors (TF) of these pollutants in vegetables. Carcinogenic and non-carcinogenic health risks from consumption of vegetables were also investigated. The level of concern for heavy metals was greater than that of OCPs as per the sediment quality guidelines. DDT, Cd, Pb and Zn had maximum concentrations corresponding to level 3 of concern, while Cr and Ni reached up to the highest i.e., 4th level of concern. Sediment samples were found to be enriched and contaminated significantly with Cd and moderately with Pb, as represented respectively by enrichment factors and contamination factors (CF). CF for metals lied in order Zn > Cd > Cr Ni > Pb Cu. Pollution load index was highest at the location lying on the exit point of Yamuna in Delhi. TF values greater than 1 were observed in majority of samples analysed for Ni, Cr, Cu and Zn. Spinach topped among vegetables in terms of metal contamination. Cd, Ni and Pb accumulated more in the roots, as against Mn, Zn, Cu and Cr which had higher accumulation in the shoots. Translocation factors were substantially high in vegetables for most of the OCPs, clearly indicating bioaccumulation and potential health risk to the consumers. Health risk to humans was assessed for non-carcinogenic and carcinogenic potentials from ingestion of vegetables. Hazard Quotient (HQ) > 1 due to radish (roots and leaves) and cauliflower consumption in children indicated non-carcinogenic risk. Hazard Index (HI) beyond 1 for all the vegetables (except onion leaves) confirmed substantial cumulative risk. Lifetime cancer risk (LCR) revealed moderate (spinach, radish, beet root and cauliflower) to low (all the others) levels of carcinogenic risk to humans. Cancer risks from γ-HCH, β- HCH, Hept, Hept Ep, Ald, p,p’-DDT, and Cr exposure through the food chain could be well established.

The Sutlej River basin of the western Himalaya (study area), owing to its unique geographical disposition, receives precipitation from both the Indian summer monsoon (ISM) and the Westerlies. The characteristic timing and intensity of the ISM and Westerlies, leaves a distinct footprint on the sediment load of the River. Analysis with the last forty years data, shows an increasing trend for temperature. While for precipitation during the same period, the Spiti watershed on the west has highest monthly accumulated precipitation with long term declining trend, in contrast to the other areas where an increasing trend has been observed. Thus, to probe the hydrological variability and the seasonal attributes, governed by the Westerlies and ISM in the study area, we analyzed precipitation, temperature, snow cover area (in % ), discharge, suspended sediment concentration (SSC) and suspended sediment load (SSL) for the period 2004 - 2008 . To accomplish the task, we used the available data of five hydrological stations located in the study area. Inter-annual shift in peak discharge during the monsoon period is controlled by the variation in precipitation, snow melt, glacier melt and temperature. Besides seasonal variability has been observed in generation of the sediments and its delivery to the river. Our analysis indicates, dominance of the Westerlies footprints in the hydrological parameters of the Spiti region, towards western part of the study area. While, it is observed that the hydrology of the Khab towards eastern part of the study area shows dominance of ISM. Further downstream, the hydrology of Nathpa station also shows dominance of ISM. It also emerged out that the snowmelt contribution to the River flow is mostly during the initial part, at the onset of the monsoon, while for rest and major part of the summer monsoon season, the River flow is augmented by the precipitation, glacial melt and some snow melt. We observed, that the SSC increases exponentially in response to increase in temperature and correlates positively with River discharge. The average daily SSL in the summer monsoon is many times more than that in the winter monsoon. The downstream decrease in steepness of the sediment rating curve is attributed to either a change in the River-sediment dynamics or on account of the anthropogenic forcing. The top 1 % of the extreme summer monsoon events (only 4 events) in our study area contribute up to 45 % of SSL to the total sediment load budget. It has also been observed that the River-sediment dynamics in the upstream catchments are more vulnerable and sensitive to the extreme events in comparison to the downstream catchments. The present study for the first time gives a holistic insight in to the complex dynamics of the hydrological processes operational in the study area. The research findings would be crucial for managing the water resources of the region and the linked water and food security.

An attempt has been made to study the subsurface groundwater discharge (SGD) in the coastal Cuddalore region of south east India. Measurement for Radon, water level, Electrical Conductivity (EC) and pH in surface water for a total of twenty hours by hourly interval has been attempted and further correlated with tidal values calculated by WX Tide 32 software. The SGD measurements were made by using a modified seepage meter. The study reveals a match with water level variation and tide with minor variation due to influx of surface water. Saline discharges, fresh groundwater discharges and surface water mixing processes were identified along the coast. Lower SGD (37.24–79.16 cm/day) was observed during fresh groundwater discharge.

The diverse habitat of the mangrove ecosystems all over the globe are under continuous threat of conversion for immediate and/or short-term economic benefits. Nonetheless, the emission of climatically relevant greenhouse gases increases with the disturbance of the mangrove sediment −this might undermine the credible reservoir of carbon within the sediment. This article attempts to estimate the environmental (carbon emission) and economic consequences of converting mangrove to cropland (especially rice paddy) based on field-scale study at three different sites (Khola, Gupti and Damra) within the Bhitarkanika mangrove for two consecutive years. The study suggests that the cumulative methane (CH4) emission was significantly higher from the rice paddy (211.3 kg ha−1) compared to the mangrove sediment (50.8 kg ha−1), while the average nitrous oxide (N2O) emission was significantly higher from the later (2.1 kg ha−1). Multivariate statistical analysis suggests that the land use was the prime controlling factor for variation in CH4 and N2O emission. Total carbon equivalent emission (CEETOT) from the rice paddy was significantly higher than mangrove during the study period. The study suggests that the economic value of the mangrove ecosystem was several folds higher than that of the rice paddy. The CEETOT of the Bhitarkanika mangrove has increased approximately 212 Gg over last few decades due to the conversion of the mangrove area to the rice paddy. Such studies are imperative in developing effective regional climate change adaptation strategies. The study advocates urgent need to educate and aware people about the benefits of the mangrove compared to the cropland.

Hamtah and Chhota Shigri are two nearby, well monitored glaciers of western Himalaya, lying in the same climatic zone and driven by the same climatic conditions. In this study, topographical characteristics of both the glacier have been explored to understand the role of topography in controlling the glacier response. Further, their topographical characteristics and possible response towards climatic variations have been compared with each other and also with that of the other glaciers in the basin to find out the suitability of these two glaciers to be considered as representative of the region. Multi sensor and multi temporal remote sensing data have been used to carry out to fulfill the objectives. It is found that being in the same climatic zone, the mean accumulation area ratio of Chhota Shigri is 54% and Hamtah is 11% between 1980 and 2014. In comparison to Hamtah, Chhota Shigri glacier has a small upslope area, low compactness ratio indicating the ability of the glacier to receive direct precipitation and solar radiation. The analysis revealed that the Chhota Shigri glacier has a closer resemblance with the other glaciers in the region than Hamtah glacier. Also, the topographical settings of Chhota Shigri glacier are suitable for recording and reflecting year-to-year climatic variations. (C) 2016, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V.

Mountain front recharge (MFR) is the contribution of mountains to recharge the aquifers in the adjacent basins. The estimation of MFR is essential to obtain a detailed investigation of recharge of the groundwater at the mountain front. This study summarises the current understanding of recharge processes by comparing daily groundwater fluctuation to daily rainfall and identifies the recharge rates. The recharge rates vary with time due to difference in water table depth and travel time. Thus to understand the MFR along the foothills of Courtallam, a total of 14 surface water, rainwater and groundwater samples were collected and measured for stable isotopes. The isotopic data were used to investigate the recharge process and to identify the elevations to recharge. The study findings also suggest that predominantly rainfall along the foothills contributes recharge to the riparian zone (basin block region), whereas foothill regions receive recharge from rainfall over mountain block.

The present study aims at assessing water quality of river Yamuna in one of the world's most polluted and populated megacities, Delhi. Conductivity, salinity and sodium content were within the permissible categories. Chloride concentration exceeded acceptable levels of drinking water guidelines. Water quality was poor at all locations with respect to heavy metal contamination, especially along the lower section of the Delhi stretch. Heavy metal concentrations were manifold higher than the acceptable limits of drinking water according to the BIS guidelines and reached similar to 29, 4.9, 10, 31, 27, 83, 7.3 and 27 times higher, respectively, for metals aluminum, copper, chromium, cadmium, iron, lead, manganese and nickel. The Najafgarh and the Shahdara drains are major point sources. Low oxidation-reduction potential reflected high organic loads and traces of eutrophication together with significant levels of nitrate and total phosphate. Discharges from agriculture, sewage and power plants could be important sources of high metal concentration. This calls for urgent measures to be taken for prevention of metal contamination in the river, through both, technology as well as implementation of regulations in order to sustain huge populations in megacities like Delhi. Waste water treatment from point sources needs tremendous improvement on the city. Treatment of the entire waste generated up to the tertiary level is required for minimizing dissolved solids, especially toxic metals, and rendering reuse in agriculture suitable. Treatment plants need proper operation, maintenance, uninterrupted power supply and regular monitoring. Various measure and programmes need to be undertaken to ensure safe reuse of wastewater.

The current study was performed to estimate the amount of inorganic forms [arsenite, As(III) and arsenate, As(V) of arsenic (As) present in groundwater (n = 18) and agricultural soils from eleven locations in the central Gangetic basin, India. Water samples were speciated using a disposable cartridge, while a microwave assisted method was used to obtain As species in agricultural soil samples. The estimation of As species concentration was performed using ion chromatography (IC) coupled with inductively coupled plasma mass spectrometer (ICP-MS) in solution matrix. Approximately 73% of the groundwater samples (n=18) show As(III) as the dominant species, while 27% reveals As(V) was the dominant species. Groundwater (80%) samples exceeded the World Health Organization (WHO) guideline value (10 μg L−1) of As. The concentration of As(III) in agricultural soil samples varies from not detectable to 40 μg kg−1 and As(V) was observed as the major species (ranging from 1050 to 6835μg kg−1) while the total As concentration varied from 3528 to 14,690 μg kg−1. Arsenate (V) species dominate in oxygen-rich environments and well-drained soils, whereas in the reducing conditions, such as regularly flooded soils, As(III) is the stable oxidation state.

To study hydrological regime over Marshyangdi (area: 3006.77 km2) and Tamor River basins (area: 4005.22 km2), an integrated approach was performed in particular to emphasize glacio-hydrological model development. Glacio-hydrological degree-day model (GDM) version 1.0, a physical-based gridded glacio-hydrological model, developed on C-Sharp (C#) and Python-programming language is developed. GDM is calibrated for the period 2004–2007 for Marshyangdi River basin (MRB) and from 2001 to 2005 for Tamor River basin (TRB) with Nash–Sutcliffe Efficiency (NSE) of 0.81 and 0.64, respectively. Furthermore, the model is validated for the period 2008–2009 for MRB and from 2006 to 2010 for TRB with NSE of 0.84 and 0.68, respectively. The snow and ice melt contribution to total discharge in MRB during calibration period is found to be 12.3% and 11.2%, respectively, whereas, during validation period, it is 9.9% and 11.8%, respectively. In case of TRB, contribution during calibration period is found to be 14.5% and 7.3%, respectively, and during validation period 12.9% and 10.6%, respectively. The highest rate of increment in minimum temperature trend over TRB and MRB is 0.027 °C/year and 0.008 °C/year. In case of maximum temperature trend, both basins show an increment rate of 0.018 °C/year. The morphometric analysis shows low drainage densities and length of overland flows of 3.66 km and 3.73 km over MRB and TRB, respectively. In Representative Concentration Pathways (RCPs) 4.5 scenario for the period 2021–2050, an average decrease in simulated discharge as − 0.087 m3/year and − 0.366 m3/year for MRB and TRB, respectively, is seen.

Stable isotopes of water (δ2H, δ18O) and δ13CTIC were used as a tool to trace the recharge processes, natural carbon (organic and inorganic) source and dynamics in the aquifers of the central Gangetic basin, India. Stable isotope (δ2H, δ18O) record of groundwater (n = 105) revealed that the groundwater of Piedmont was recharged by meteoric origin before evaporation, while aquifers of the older and younger alluvium were recharged by water that had undergone evaporation loss. River Ganges and its tributaries passing through this area have very little contribution in recharging while ponds play no role in the recharging of adjacent aquifers. The connectivity of shallow aquifers of aquitard formation (comprised of clay/sandy clay with thin patches of fine grey sand), i.e. 25–60 m below ground level (bgl) with the main upper aquifer (at a depth of >120 m bgl) was found to be higher in older and younger alluvium. Negative values of δ13CTIC (median −9.6 ‰; range −13.2 to −5.4 ‰) and high TIC (median 35 mM; range 31–46 mM) coupled with low TOC (median 1.35 mg/L; range 0.99–1.77 mg/L) indicated acceleration in microbial activity in the younger alluvium, especially in the active floodplain of river Ganges and its proximity.

This paper presents a review of Late Quaternary climatic changes and glacier variability in the Himalaya and East Africa, focusing on the role of Indian Summer Monsoon (ISM), East African monsoon, and Westerlies monsoons. Multi-proxy studies which are based on five different archives (lakes, peat bogs, speleothems, marine sediments, and ice cores) including sixty-six records from India and nearby regions, particularly in the Himalaya and in addition to six archives from the equatorial Eastern part of Africa encompasses with high-resolution published and unpublished records for the last 50 ka BP. The proxy data is discussed towards REMO-ESM model Coupled Model Intercomprasion Project phase 5 (CMIP5 Project) results. Our results indicate that both Western Himalaya and East Africa had undergone mega-droughts from ~17.0–15.0 ka BP, and precipitation had increased during the Early Holocene (10.0–7.0 Ka BP) during the time span when the Westerlies dominated regions. The model results suggest that the Westerlies monsoon has significantly contributed to the Northwestern Himalaya and somewhat to a lesser degree to the Western Himalaya and lower solar insolation in the winters did support the glacier advance during the LGM. The time series from the proxy data are compared with glacier fluctuations in different valleys to understand the response of the aforementioned monsoon system including other forcing factors which drive these variabilities. The review results indicate that the Westerlies was the main driver of the climate and glacier fluctuations in Northwestern Himalaya during the Late Quaternary. The Early and Late Holocene glacier fluctuation was mainly controlled by Westerlies precipitation in Northwestern Himalaya and the ISM controlled the glacier fluctuations in the Western Himalaya during Late Quaternary.

Concentrations of inorganic forms [arsenite, As(III) and arsenate, As(V) of arsenic (As) present in groundwater, agricultural soils and subsurface sediments located in the middle Gangetic plain of Bihar, India were determined. Approximately 73% of the groundwater samples (n = 19) show As(III) as the dominant species while 27% reveals As(V) was the dominant species. The concentration of As(III) in agricultural soil samples varies from not detectable to 40 μg/kg and As(V) was observed as the major species (ranging from 1050 to 6835 μg/kg) while the total As concentration varied from 3528 to 14,690 μg/kg. Total extracted concentration of As was higher in the subsurface sediments (range 9119–20,056 μg/kg in Methrapur and 4788–19,681 μg/kg in Harail Chapar) than the agricultural soil, indicating the subsurface sediment as a source of As. Results of X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) revealed the presence of hematite and goethite throughout the vertical section below while magnetite was observed only in the upper oxidized layer at Methrapur and Harail Chapar. Alteration of Fe-oxides and presence of fibrous goethite indicating presence of diagenetic sediment. Siderite plays a crucial role as sinks to the As in subsurface sediments. The study also concluded that decomposition of organic matter present in dark and grey sections promote the redox conditions and trigger mobilization of As into groundwater.

This manuscript discusses about the solute acquisition processes controlling hydrogeochemistry and suspended sediment characteristics of meltwater of the Batal glacier, Western Himalaya, India. The predominance of anions and cations in meltwater follows the order: SO4 2− > HCO3 − > Cl− > NO3 − and Ca2+> Mg2+> Na+> K+, respectively. High excess of (Ca + Mg) over (Na + K), high input of (Ca + Mg) to the TZ+ (total cations) and very low input of (Na + K) to the total cations (TZ+) demonstrate that meltwater chemistry of Batal glacier is predominantly regulated by carbonate type weathering along with minor input from silicate type weathering. Sulphide oxidation is the dominant mechanism responsible for delivery of hydrogen ions (protons) for weathering in the glacier environment, which is revealed by C-ratio of meltwater. The Piper trilinear plot indicates that Ca–SO4 is the prevalent water type in the study area with dominancy of (Ca + Mg) (alkaline earth metals) over (Na + K) (alkali metals) and dominancy of (SO4 + Cl) (strong acid) over (HCO3) (weak acid). Interrelation among the different chemical constituents of meltwater and various factor regulating meltwater chemistry of the Batal glacier are evaluated by multivariate statistical analysis. Average suspended sediment concentrations in meltwater of the study area for August and September 2014 were computed to be 706 and 98.3 mg/l, respectively. These results show that in August suspended sediment concentrations is high and in September its concentration is low.

The occurrence of arsenic in drinking water and its detrimental effects have drawn much attention in recent years. Several studies have been conducted in the deltaic plains of River Ganga, NE part of the India, and in other countries, but no systematic study was conducted in South India on occurrence of arsenic in groundwater. The main aim of this study is to determine the level of arsenic in groundwater and to understand the relation with other geochemical parameters of groundwater in the south-eastern coastal aquifer at Kalpakkam region, India. This region is represented by three different lithologies, viz. charnockites, flood plain alluvium and marine alluvium. Twenty-nine representative samples of groundwater were collected and analysed for major ions, metals and isotopes such as 2H and 18O. In addition, geophysical method was also attempted to understand the subsurface condition. The spatial variation in arsenic (As) indicates that higher concentration was observed around the landfill sites and irrigated regions, which was supported by geochemical, statistical and isotopic inferences. The variation in the As with depth, lithology and sources has been clearly brought out. Though the values of As does not exceed the drinking water permissible limit (10 mg/l), it has reached a near permissible level of 8.7 ppb. Hence, it is essential to understand the geochemical behaviour of As for a proper future management of the water resource in the study area.

The expedited advent of urbanization and industrialization for economic growth has adversely affected the biological diversity, which is one of the major concerns of the developing countries. Microbes play a crucial role in decontaminating polluted sites and degrades pollution load of textile effluent. The present study was based on identification of microbial diversity along the Noyaal river of Tirupur area. River water samples from industrial and non-industrial sites and effluent samples of before and after treatment were tested and it was found that microbial diversity was higher in the river water at the industrial site (Kasipalayam) as compared to the non-industrial site (Perur). Similarly, the microbial populations were found to be high in the untreated effluent as compared to the treated one by conventional treatment systems. Similar trends were observed for MBR treatment systems as well. Pseudomonas sp., Achromobacter sp. (bacterial species) and Aspergillus fumigates (fungal species), found exclusively at the industrial site have been reported to possess decolorization potential of dye effluent, thus can be used for treatment of dye effluent. The comparison of different microbial communities from different dye wastewater sources and textile effluents was done, which showed that the microbes degrade dyestuffs, reduce toxicity of wastewaters, etc. From the study, it can be concluded that the microbial community helps to check on the pollutants and minimize their affect. Therefore, there is a need to understand the systematic variation in microbial diversity with the accumulation of pollution load through monitoring.

Glaciers have a high impact in the socio-economic sectors including water supply, energy production, flood and avalanches. A high precision digital elevation model (DEM) is required to monitor glaciers and to study various glacier processes. The present study deals with the qualitative and quantitative evaluation of the DEM generated from the bistatic TanDEM-X data by comparing it with GPS, Ice, Cloud, and land Elevation Satellite (ICESat) data and standard global DEMs such as Shuttle Radar Topography Mission (SRTM) and Advanced Space-borne Thermal Emission and Reflection Radiometer Global DEM (ASTER GDEM). The study area consists of highly undulating glaciated terrain in western Himalaya, India. The results reveal that TanDEM-X is slightly better than SRTM both qualitatively and quantitatively, whereas ASTER GDEM showing maximum discrepancy among the three DEMs. The Root Mean Square Error (RMSE) of the TanDEM-X DEM with respect to GPS is 3.5m at lower relief and 11.9m at glaciated terrain, against 6.7 and 12.5m for SRTM and 9.3 and 19.8m for ASTER GDEM, respectively, for the same sites. On an average, for the whole study area, the RMSE of TanDEM-X is 7.9m, SRTM is 9.3m and ASTER GDM is 14.2m. The RMSE of TanDEM-X, SRTM and ASTER GDEM with respect to ICESat are 16.3, 19.9 and 101.1m, respectively. It is evident from the analysis that though SRTM is closer to TanDEM-X in terms of accuracy in the mountainous terrain, however, TanDEM-X will be more useful for studying glacier dynamics and topography.

A geochemical assessment of seasonal dynamics in the groundwater chemistry of the National Capital Territory (NCT), Delhi, was attempted through geochemical modelling, mineral precipitation sequences with rainfall and water evaporation cycle. Saturation indices calculated using PHREEQC indicated that the degree of water–rock equilibrium changes significantly from pre-monsoon to post-monsoon. The schematic model of SI change with water table fluctuation showed that during monsoon, as rainwater percolates through the soil, partial pressure of CO2 becomes higher than that of the atmospheric value and led to the formation of more carbonic acid that react with the carbonate minerals to produce $${{{\text{HCO}}_{3}^{-} }}$$ , Mg2+ and Ca2+. The thermodynamic stability relationships of water chemistry in the Na, K, Ca and Mg silicate systems showed that for the samples with higher EC equilibrium between clay and primary minerals is not likely to be the main processes controlling variation in the groundwater chemistry. Chloro-alkaline indices (CAI) are positive when the groundwater level is high and become negative with the lowering of water level, i.e. when water level is high, reverse ion exchange is dominant. In case of pre-monsoon season, lower and negative value of CAI-1 and CAI-2 indicates dominance of ion exchange process and increases dissolved solid concentration in groundwater. The conceptual geochemical model depicted that water table fluctuation resulting from heavy pumping/withdrawal and recharge in association with the variation in DO, $${{{\text{HCO}}_{3}^{-} }}$$ and Fe regulates the water–mineral equilibrium. The conceptual geochemical model explained the hydrogeochemical processes and their variations with water table fluctuation and, thus, highlighted the descriptive capabilities of PHREEQC. The study suggested that in the subsurface environment, complex interactions are simultaneously functioning, and hence, significant seasonal variations are likely to be very influential due to monsoonal recharge and subsequent changes in the saturation states of the water.

Ensuring the water availability with better quality and quantity for all through sustainable management of it by the year 2030 is one of the top priorities of the United Nations Sustainable Development Goals (SDGs). With having proper knowledge about drivers causing water quality deterioration at right time will help policy makers to take right measures to retrieve the quality back to normal or at least stop further degradation. With the above theme, this work tries to give insight about the factors affecting water quality/quantity and strategy or action plan needed to overcome the challenges by enhancing community resilience for lake Baikal and Baikal basin. Main factors affecting water quality include anthropogenic activities well supported with lack of proper law enforcement, quality monitoring and climate variability.

The hydrochemical study of meltwater draining from a catchment dominated by snowmelt in a cold-arid trans-Himalayan region of Ladakh, India, was carried out for an entire melting season (May–September) during the year of 2010. Cation concentration in the meltwater shows a consistent trend of Ca > >Mg > Na > K for this period. Carbonate weathering has been identified as the dominant process controlling the dissolved ion chemistry of meltwater in the study area. There are indications that atmospheric aerosols contain alkaline dust, sea salt and anthropogenic aerosols like NO3 and SO4 that might have also added some solute to the system. Meltwater chemistry has been showing an intra-annual variation with highest concentration for most of the dissolved solutes during the late melt period, pointing towards the contribution of ground ice melt to the catchment runoff. The lowest concentration during the peak melt period is due to higher contribution from snow melt which has less residence time to interact with rock. Cationic denudation rate for this catchment has been estimated as 778 meq m−2 a−1, while the average total dissolved solids flux for early, peak and late melt period is 0.64 t day−1, 3.02 t day−1, 1.31 t day−1, respectively.

The systematic and comprehensive geochemical analysis of fluoride (F) in twenty agricultural soil samples was carried out to understand spatial variability, mechanism of retention and release, and the areas of potential risk due to high concentrations of F in soil around Sidhi District, Central India. The spatial variations in physico-chemical parameters revealed significant difference in the methods of cultivation due to geomorphological constraints, availability of surface water and ground water etc., in the study area. The north and small pocket in central Sidhi were rich in fertile soils due to availability of surface and ground water. The southern and eastern Sidhi were rainfed areas, hence, the monocropping system by traditional methods showed less impact on the soil physico-chemical parameters. The soil F varied from 366.94 to 1178 mg/kg and 2-4 times greater than the background soil value (320 mg/kg) of the world. The pollution indexes were > 1 indicating prevalence of elevated soil fluorine.

The distribution, enrichment, and ecotoxicity potential of Bangladesh part of Sundarban mangrove was investigated for eight trace metals (As, Cd, Cr, Cu, Fe, Mn, Pb, and Zn) using sediment quality assessment indices. The average concentration of trace metals in the sediments exceeded the crustal abundance suggesting sources other than natural in origin. Additionally, the trace metals profile may be a reflection of socio-economic development in the vicinity of Sundarban which further attributes trace metals abundance to the anthropogenic inputs. A total of eleven surficial sediment samples were collected along a vertical transect along the freshwater-saline water gradient. The sediment samples were digested using EPA 3051 method and were analyzed on ICP-MS. Geo-accumulation index suggests moderately polluted sediment quality with respect to Ni and As and background concentrations for Al, Fe, Mn, Cu, Zn, Pb, Co, As, and Cd. Contamination factor analysis suggested low contamination by Zn, Cr, Co, and Cd, moderate by Fe, Mn, Cu, and Pb while Ni and As show considerable and high contamination, respectively. Enrichment factors for Ni, Pb, and As suggests high contamination from either biota or anthropogenic inputs besides natural enrichment. As per the three sediment quality guidelines, Fe, Mn, Cu, Ni, Co, and As would be more of a concern with respect to ecotoxicological risk in the Sundarban mangroves. The correlation between various physiochemical variables and trace metals suggested significant role of fine grained particles (clay) in trace metal distribution whereas owing to low organic carbon content in the region the organic complexation may not be playing significant role in trace metal distribution in the Sundarban mangroves.

We present the updated glaciological mass balance (MB) of Chhota Shigri Glacier, the longest continuous annual MB record in the Hindu-Kush Karakoram Himalaya (HKH) region. Additionally, 4 years of seasonal MBs are presented and analyzed using the data acquired at an automatic weather station (AWS-M) installed in 2009 on a lateral moraine (4863ma.s.l.). The glaciological MB series since 2002 is first recalculated using an updated glacier hypsometry and then validated against geodetic MB derived from satellite stereo-imagery between 2005 (SPOT5) and 2014 (Pléiades). Chhota Shigri Glacier lost mass between 2002 and 2014 with a cumulative glaciological MB of –6.72mw.e. corresponding to a mean annual glacier-wide MB (Ba) of –0.56mw.e. a–1. Equilibrium-line altitude (ELA0) for the steady-state condition is calculated as ~4950ma.s.l., corresponding to an accumulation–area ratio (AAR0) of ~61%. Analysis of seasonal MBs between 2009 and 2013 with air temperature from AWS-M and precipitation from the nearest meteorological station at Bhuntar (1050ma.s.l.) suggests that the summer monsoon is the key season driving the interannual variability of Ba for this glacier. The intensity of summer snowfall events controls the Ba evolution via controlling summer glacier-wide MB (Bs).

The Himalayan Mountains and valley glaciers within it are coupled in such a way that they maintain the ecosystem along the draining stream from the young to old stage. They produce meltwater and nutrient-rich sediments, which serve as precious resources for low-lying areas. Meltwater is assumed to be an important agent of transportation and deposition of sediments in warm-based valley glaciers. Overall, the glacial environment acts as a good erosional system, and the sediments produced form a good-quality aquifer above the hard bedrock in the outwash plain. The glaciofluvial and glaciolacustrine sediments were collected from the Chandra Basin and analysed for the permeability, porosity, density and statistical parameters. Correlation among the different parameters was explained through the regression analysis. The correlation between permeability and mean grain size showed a good regression coefficient, R2 = 0.86 and R2 = 0.97, for glaciofluvial and glaciolacustrine sediments respectively. Correlation between density and porosity was also established against the mean grain size with a good regression coefficient. The physioempirical parameters, effective diameter (D10) and coefficient of uniformity (Cu) were also examined for their dependability on permeability. Hence, this preliminary study attempts to use sediment grain size and texture as a tool to understand the permeability, porosity, density and movement and mobility of water through the glaciofluvial and glaciolacustrine sediments. Also, the correlation study showed that the mean grain size could be used as a factor for predicting the physioempirical model in that region.

This systematic study was carried out with objective to delineate the various sources responsible for $$\hbox {NO}_{3}^{-}$$ contamination and $$\hbox {F}^{-}$$ enrichment by utilizing statistical and graphical methods. Since Central Ground Water Board, India, indicated susceptibility of $$\hbox {NO}_{3}^{-}$$ contamination and $$\hbox {F}^{-}$$ enrichment, in most of the groundwater, $$\hbox {NO}_{3}^{-}$$ and $$\hbox {F}^{-}$$ concentration primarily observed $${>}45$$ and $${>}1.5~\hbox {mg/L}$$ , respectively, i.e., higher than the permissible limit for drinking water. Water Quality Index (WQI) indicates $${\sim }22.81\%$$ groundwater are good-water, $${\sim }71.14\%$$ groundwater poor-water, $${\sim }5.37\%$$ very poor-water and 0.67% unsuitable for drinking purpose. Piper diagram indicates $${\sim }59.73\%$$ groundwater hydrogeochemical facies are Ca–Mg– $$\hbox {HCO}_{3 }$$ water-types, $${\sim }28.19\%$$ Ca–Mg– $$\hbox {SO}_{4}$$ –Cl water-types, $${\sim }8.72\%$$ Na–K– $$\hbox {SO}_{4}$$ –Cl water-types and 3.36% Na–K– $$\hbox {HCO}_{3 }$$ water-types. This classification indicates dissolution and mixing are mainly controlling groundwater chemistry. Salinity diagram indicate $${\sim }44.30\%$$ groundwater under in low sodium and medium salinity hazard, $${\sim }49.66\%$$ groundwater fall under low sodium and high salinity hazard, $${\sim }3.36\%$$ groundwater fall under very-high salinity hazard. Sodium adsorption ratio indicates $${\sim }97\%$$ groundwater are in excellent condition for irrigation. The spatial distribution of $$\hbox {NO}_{3}^{-}$$ indicates significant contribution of fertilizer from agriculture lands. Fluoride enrichment occurs in groundwater through the dissolution of fluoride-rich minerals. By reducing the consumption of fertilizer and stress over groundwater, the water quality can be improved.

A geochemical and speciation study of As, Fe, Mn, Zn, and Cu was performed using sequential extraction and statistical approaches in the core sediments taken at two locations—Rigni Chhapra and Chaube Chhapra—of the central Gangetic basin (India). A gradual increase in the grain size (varying from clay to coarse sands) was observed in both the core profiles up to 30.5 m depth. The concentrations of analyzed elements ranged as follows: 6.9–14.2 mg/kg for As, 13,849–31,088 mg/kg for Fe, 267–711 mg/kg for Mn, 45–164 mg/kg for Cu for Rigni Chhapra while for Chaube Chhapra the range was 7.5–13.2 mg/kg for As, 10,936–37,052 mg/kg for Fe, 267–1052 mg/kg for Mn, 60–198 mg/kg for Zn and 60–108 mg/kg for Cu. Significant amounts (53–95%) of all the fractionated elemental concentrations were bound within the crystal structure of the minerals as a residual fraction. The reducible fraction was the second most dominant fraction for As (7% and 8%), Fe (3%), Mn (20% and 26%), and Cu (7% and 6%) respectively for both the cores. It may be released when aquifers subjected to changing redox conditions. The acid soluble fraction was of most interest because it could quickly mobilize into the water system which formed the third most dominating among all three fractions. Four color code of sediments showed an association with total As concentration and did not show a relation with any fraction of all elements analyzed. The core sediment was observed enriched with As and other elements (Cu, Fe, Mn, and Zn). However, it fell under uncontaminated to moderately contaminate which might exhibit a low risk in prevailing natural conditions. X-ray diffraction analyses indicated the availability of siderite and magnetite minerals in the core sediments in a section of dark grey with micaceous medium sand with organic matter (black).

The current study was focused on the characterization of recharge, weathering processes and to check the aptness of groundwater for household and agriculture utility in the Chhaprola industrial area located in Gautam Buddha Nagar district of Uttar Pradesh, India. Groundwater samples (n = 33) were analyzed for major cations and anions from which (n = 22) were analyzed for stable isotopic records (δ2H and δ18O). Solute chemistry revealed neutral to moderately basic nature (pH ranged 6.4–8.8) and showed a higher (ranged 552–3130 µS/cm) of electrical conductivity. Isotopic signals ranged from − 8.7 to − 3.3‰ for δ18O and − 60.1 to − 37‰ for δ2 H. Bivariate plot of stable isotopes (δ 18O and δ2 H) showed that majority of the samples fell below the global meteoric water line (GMWL) and local meteoric water line (LMWL) of New Delhi, indicating enrichment of heavier isotopes in the aquifers, which explain that recharging water, has undergone evaporation before recharging the aquifer. Monsoonal precipitation was observed as the major source of aquifer recharge in the surveyed area. Vertical hydraulic connectivity of the aquifer layers was traced with the help of isotopic record which exhibited a more negative intercept for shallow depth tube well than the middle depth tube well. About 76% of the samples exhibited negative Schoeller index thereby indicated cation-anion exchange reactions while the remaining samples depicted the Base Exchange Reactions. Sodium-normalized Ca versus Na-normalized Mg and HCO 3, indicated an equal contribution of silicate and carbonate type weathering on global-average weathering system. About 52% of the groundwater samples fell into the Ca-HCO3- water type while remaining samples fell into 33% and 15% of Na-HCO3 and Mg-HCO3 type, respectively. Water quality indices (viz. residual sodium carbonate, Kelly index, permeability index, magnesium hazard, and Chloroalkaline indices) revealed unsuitability of the groundwater for drinking and irrigation purpose at few locations.

India has a very long coastline compared to other countries in the world and is considered as the backbone of our national economy. One-fourth of the country’s population lies in this region; the most fertile agricultural land is situated in this area, and it occupies the most potential aquifer systems of the country which faces multifaceted complex problems like seawater intrusion, land use/land cover changes, climate change, and human-induced anthropogenic problems like discharge of sewage effluents, agricultural, salt pan, and aquacultural activities. It is also highly vulnerable to extreme events, such as storms, which impose substantial costs on coastal communities. Numerous rivers enter to the coast that tends to form estuaries and mixes with sea which includes a huge complex ecosystem. The population density increases the risks and vulnerability of the coastal states. The anticipated sea level rise by climate changes affects the coastal aquifers which push the freshwater–seawater interface and makes the shallow aquifers saline. Rivers are the major contributory of the pollution in the coast whereas all rivers are polluted due to industrial effluents and sewage disposal. The various studies on different aspects of hydrogeochemical approach explain the degradation of coastal regions and also various mitigations to overcome these problems.

The chapter presents a comparative account of trace metal distribution, their accumulation in sediments as well as in biota across the Indian and Bangladesh estuarine-mangrove complex through published literature. The study shows that trace metals like Fe and Cd show high contamination in most of Indian and Bangladesh mangrove ecosystem whereas other trace metals like Al, As, Cr, Co, Cu, Mn, Ni, Pb and Zn, show variable contamination in different mangrove settings with ‘low’ to ‘moderate’ value. Tsunamigenic sediment shows higher concentration of almost all trace metals due to waste and discharge brought by tsunami wave or sediment from deep shore of ocean. Speciation of trace metals show dominance of Fe, Cd, Cu, Ni, Pb and Zn mostly in residual fraction, thus making it unavailable in prevalent environments. Whereas, Mn can be found in exchangeable fractions that are readily available and potential risks. Trace metals accumulation in fishes shows the following order Cd>As>Ni>Cu>Pb>Cr, with highest accumulation of Cd; pelagic fishes exhibit lower values of heavy metals than the bottom dwelling fishes. Bioaccumulation of Cu and Zn in both gastropods and bivalves was higher than bioavailability. So, due to increased risk of trace metals pollution in the estuarine-mangrove complex and loss of mangrove biodiversity, there is dire need of in-depth study and better management practices in the tropical mangrove ecosystem of India and Bangladesh.

Intense agricultural and mining/industrial activities make groundwater quality vulnerable to contaminants. This study conducted in one of the mining areas of Panna district evaluated the factors influencing the groundwater hydrogeochemistry using water quality parameters and multi-isotopic approach considering the fact that groundwater is the only major source of drinking water. Forty-five water samples comprising both shallow and deep aquifers were collected and analyzed for major ions, δ 18O, and δD. The geochemical data were used to characterize and classify water samples based on a multitude of ion plots and diagrams. The groundwater in the region is found to be contaminated with fluoride and nitrate. The sources for fluoride are mostly geogenic in nature. The alkaline nature of groundwater triggers replacement of the exchangeable fluoride from minerals like biotite/muscovite and results in its enrichment. In addition, it is contributed through leaching of fluorides from granitic rocks, abundantly present in the study area. The weathering of these fluoride-bearing minerals releases fluoride into the groundwater. On the other hand, nitrate enrichment is mainly attributed to leaching from untreated sewerage system and agricultural runoff containing nutrients from excess use of fertilizers. The stable isotopic composition for most of the collected samples was found to be near the local meteoric water line (LMWL), i.e., origin of ground water is meteoric in principle; however, the point away from the LMWL might favor exchange with rock minerals and evaporation processes. This study sets an important background for decision makers to take the suitable countermeasures from the public health perspective for sustainable water resources management.