Browsing by Author "Jitendra Pandey"

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Alkaline phosphatase as a bio-indicator of phosphorus-eutrophy in freshwater ecosystems: A review
(Elsevier B.V., 2023) Madhulika Singh; Jitendra Pandey
Limnologists have greatly advanced the understanding of indicators of phosphorus (P)-eutrophy in surface waters. Biotic variables such as macro-invertebrates, fish, zooplankton, benthic algae, and diatoms are extensively used for bio-assessment of eutrophy. New concepts highlight the importance of bed-sediment based “response” variables predicting functional shifts during eutrophication. A cross analysis of studies reveals that alkaline phosphatase (ALP), which serves as a proxy of P-deficiency, and also as an indicator of benthic anoxia/hypoxia-driven feedbacks, can be an easy to measure, cost-effective and reliable tool to assess changes in nutrient stoichiometry, trophic status, and ecological functioning at the sediment–water interface. Here, the issues discussed in this paper are highly relevant to explore new domains of research and “response” based ecosystem models for potential eutrophication management decisions. Because ALP is used in molecular cloning and fingerprinting studies, it is suggested that approaches based on the “omics” technologies need to be used to explore more intricate connections to empirically address ALP-P-eutrophy linkages to track eutrophication in freshwater ecosystems. © 2023
Alternative alert system for Ganga river eutrophication using alkaline phosphatase as a level determinant
(Elsevier B.V., 2017) Jitendra Pandey; Amita Yadav
Short-term variations in phosphorus (P) concentrations must be considered while assessing the long-term changes in trophic status and estimating the P load and export. Furthermore, given the challenges of conventional monitoring of river systems, a sediment-specific biomonitoring tool may be more successful inferring P related human controls. In this study, conducted along a 37 km river channel representing up-and downstream urban control, and through a trajectory from a major point source (Assi drain), we tested the patterns of concordance between alkaline phosphatase (AP) activity and soluble reactive-P (SRP) and between AP activity and trophic status in the Ganga River. To validate data comparison, we selected a reference site at Dev Prayag, situated ∼1130 km upstream to the main study stretch. Samples were collected for three consecutive year (March 2013 to February 2016) with respect to atmospheric deposition, surface runoff, point source loading, river water and sediment analysis. For trajectory analysis, samples were collected from 15 locations starting from the drain outlet (zero distance) upto 1.5 km downstream with sampling location 100 m away from the preceding one. We found marked spatial and temporal variations in P concentrations which could be traced by quantifying the AP activity. The AP activity, recorded highest at reference site, declined with increases in P; and at drain mouth it was close to zero reflecting strong influence of P level on alkaline phosphatase activity in the river. We used canonical correlation analysis (CCorA) to test the degrees of concordance and similarity in different variables. Most of the environmental variables and indicators of eutrophy appear largely clustered at one side of the coordinate separating AP activity and dissolved oxygen towards opposite side of the axis. The dynamic fit function relating AP activity with different variables showed significant positive correlation with DO (R2 = 0.67; p < 0.001) and negative correlations with BOD (R2 = 0.82; p < 0.001), Chl a biomass (R2 = 0.52; p < 0.001) and trophic status index (R2 = 0.54 (Chl a), 0.96 (DRP); p < 0.001). Furthermore, the enzyme activity did not show significant negative correlation with heavy metals in sediment. Because anthropogenic activities continue to enhance P loads; AP is inhibited directly by P availability; and eutrophy feedbacks sediment P release, our observations on P-AP activity relationship provide a valuable alternative means for detecting P related controls on water quality, trophic status and biogeochemical feedbacks in human impacted rivers. © 2017 Elsevier Ltd
An ecological response index for simultaneous prediction of eutrophication and metal pollution in large rivers
(Elsevier Ltd, 2019) Deepa Jaiswal; Jitendra Pandey
The ecological responses of riverine ecosystems are strongly influenced by anthropogenic perturbations. However, high-resolution quantitative shifts in the ‘ecosystem responses’ to multiple human pressures in riverine ecosystems are not well understood. Given that, in most of the anthropogenically impacted rivers, eutrophy and metal pollution occur simultaneously, we explored FDAase activity, microbial quotient, and a sum of six heavy metals in an empirical relationship to develop an ‘ecological response index’ (ERI). The FDAase, a measure of fluorescein diacetate hydrolytic activity, and microbial quotient, the proportion of microbial biomass-C to the total organic carbon (Cmic/TOC) were used to address ‘ecosystem responses’ to C-eutrophy and metal pollution. We analyzed 1404 water samples and 2808 sediment samples collected from the land-water interface (LWI) and riverbed sediment (50 m reach) of 24 sites along a 528 km main stem and from 30 sites downstream two point sources of the Ganga River. The index was compare to Carlson's trophic state index (TSI) to quantify eutrophy and Håkanson's risk index (RI) and modified ecological risk index (MRI) for metal pollution. The ERI showed strong correlation with TSI (R2 = 0.70–0.97; p < 0.001), RI (R2 = 0.76–0.94; p < 0.001) and MRI (R2 = 0.76–0.96; p < 0.001). The ERI developed here is the first ‘response index’ against multiple human pressures, able to quantitatively predict C-eutrophication and metal pollution simultaneously in large rivers. © 2019 Elsevier Ltd
Anthropogenic drivers shift diatom dominance-diversity relationships and transparent exopolymeric particles production in River Ganga: Implication for natural cleaning of river water
(Indian Academy of Sciences, 2017) Usha Pandey; Jitendra Pandey; Anand V. Singh; Abha Mishra
We studied the relationships among diatom biodiversity, transparent exopolymeric particles (TEP) and water quality at the confluences of four tributaries of River Ganga (Yamuna, Assi, Varuna and Gomti) during low flow. Diatom abundance changed with concurrent shifts in water chemistry with dominance- diversity curves markedly skewed from a log-normal pattern. Canonical correspondence analysis segregated chloride-loving and calcifilous species from N- and P-favoured taxa. Despite pollution-induced reduction of diatom diversity, TEP production continued to rise plausibly due to dominance transference of TEP producers. However, with further increase in nutrient pollution, TEP declined. Since TEP enhances sedimentation removal of carbon, nutrients and heavy metals, the present study confirms one of the fundamental mechanisms that underline the self-purification capacity of River Ganga and has relevance from a biodiversity/river conservation perspective.
Anthropogenic-induced shifts in salinity and nutrient status of two freshwater tropical lakes in India
(2017) Anuya Verma; Jitendra Pandey
An understanding of ongoing changes in salinity and nutrient status, as influenced by anthropogenic forcing factors, is important for integrated lake basin management (ILBM) and conservation of water resources in dry tropical regions. This study analysed a range of water quality attributes, including salinity, nitrate (NO3 −), ammonia (NH4 +), phosphate (PO4 3−) and dissolved organic carbon (DOC) in two freshwater lakes in Rajasthan, India for three consecutive years (2000–2002). Between-lake comparisons indicated marked differences in most of the water quality variables. The pH in both study lakes remained above neutral. Water hardness, salinity and concentrations of total dissolved salts (TDS), chlorides, NO3 −, NH4 +, PO3 3− and DOC were high in Lake Udaisagar, which received inputs from agricultural drainage and urban–industrial releases. The DOC in Lake Baghdara, which drains a woodland catchment, was similar to that for Lake Udaisagar, indicating the role of allochtonous inputs in the build-up of DOC. The results of this study indicated that increasing human interferences have increased the nutrient concentrations in Lake Udaisagar. This factor, coupled with extended periods of dryness, drives these two freshwater lakes towards a high salinity. This study provides evidence of a human-induced salinity increase and has relevance for ILBM and for the conservation of freshwater resources in dry regions. © 2017 John Wiley & Sons Australia, Ltd
Anthropogenically enhanced sediment oxygen demand creates mosaic of oxygen deficient zones in the Ganga River: Implications for river health
(Academic Press, 2019) Deepa Jaiswal; Jitendra Pandey
Dissolved oxygen (DO) plays a major role in sustaining aquatic communities; its concentration and regulatory determinants are considered a key node predicting eutrophy, ecosystem health, and biogeochemical feedbacks. Here we report the status of dissolved oxygen deficit (DOD; hypoxia), and its mechanistic links with sediment oxygen demand (SOD) in the Ganga River. We conducted two independent but interlinked studies during summer low flows of three consecutive years (2016–2018) considering: 1) a 518 km middle segment of the Ganga River between Kanpur upstream and Varanasi downstream; and 2) trajectory analyses downstream two point sources, one flushing industrial effluents (Wazidpur drain) and the other with urban sewage (Assi drain). The concentration of DO at sediment-water interface (DO sw ) did appear < 2.0 mg L −1 (hypoxia) at Jjmu; and up to 600 m and 800 m downstream Assi and Wazidpur drain respectively. The DOD at sediment-water interface (DOD sw ) was highest at Jjmu and did not show a significant decrease up to 300 m downstream to point sources. The SOD which varied between 2.03 and 13.16 (main river stem); 4.39 and 16.81 (Wazidpur drain); and between 2.00 and 13.50 g O 2 m −2 d −1 (Assi drain), was found to be a major contributor of DOD. Principal component analysis (PCA) and non-metric multi-dimensional scaling (NMDS) separated DO and alkaline phosphatase (AP) opposite to oxygen-consuming processes and sediment-P release. Using a dynamic fit model, we tested the dependence of sediment-P release on DO sw and DOD sw . A large increase in the sediment-P release with increasing DOD sw and decreasing DO sw indicated that the system may compromise its resilience in long-term future in terms of self-fertilization and P-eutrophy if the similar magnitude of anthropogenic pressure is continued. The study advances our understanding towards DOD associated habitat fragmentation, ecosystem resilience and niche opportunities useful for recovery and management of the Ganga River. © 2019 Elsevier Inc.
Anthropogenically induced shifts in N:P:Si stoichiometry and implications in Ganga River
(Libertas Academica Ltd., 2016) Jitendra Pandey; Shraddha Tripathi; Usha Pandey
Human-induced N:P:Si imbalances and associated shifts in nutrient limitation in Ganga River remain relatively uncertain despite recent studies highlighting its importance. The goal of this watershed-scale study was to investigate the nutrient-limiting status of Ganga River, as influenced by atmospheric deposition (AD) and catchment runoff together with urban–industrial development. AD was highest in middle watershed, where AD of NO3− ranged from 10.56 to 28.93, AD of NH4+ from 4.26 to 15.42, and AD of PO43− from 1.82 to 2.94 kg ha−1 year−1. The results showed that ADcoupled catchment runoff is an important factor, in addition to direct urban–industrial release, causing N:P:Si imbalances that lead to N over P limitation (N:P < 16:1) and Si over N limitation (Si:N < 1) in the river. The skewed N:P:Si ratios observed here may have important effects on phytoplankton/diatom growth and trophic cascades and consequently on river ecology. This study that forms the first report on changing atmosphere–land–water N:P:Si linkages suggests that the current policy on Ganga rejuvenation needs to focus more strongly on cross-domain drivers of stoichiometric imbalances and approaches to minimize them. © the authors, publisher and licensee Libertas Academica Limited.
Assessment of energy generation potentials of MSW in Delhi under different technological options
(2013) Monojit Chakraborty; Chhemendra Sharma; Jitendra Pandey; Prabhat K. Gupta
Municipal solid waste (MSW) is an important source of methane emission which is a greenhouse gas (GHG) and has high potential for its use as energy source. A study has been carried out to find out the energy generation potential of MSW being dumped in Delhi's three landfills viz. Ghazipur (GL), Bhalswa (BL) and Okhla (OL). Five technologies for waste to energy generation, namely biomethanation, incineration, gasification/pyrolysis, refused derived fuel (RDF) and plasma arc gasification have been evaluated for computation of possible energy (WTE) generation potential of MSW under ideal conditions using the MSW specific characteristic parameters. Bulk waste with and without pre-segregation of reusable high carbonaceous materials have been considered to develop range of energy generation potentials under two scenarios of with and without segregation of MSW. USEPA-LandGem model version 3.02 has been used to get LFG generation potential of Delhi's landfills. The potential of biomethanation process for producing energy has been found to be in the range of 3-10, 3-8 and 2-8 MW/day from the MSW deposited in GL, BL and OL respectively. The energy generation potentials of the MSW deposited in GL, BL and OL have been found to be in the range of 8-24, 7-22 and 7-19 MW/day for incineration process; 17-32, 16-29 and 11-25 MW/day from gasification/pyrolysis process; 9-19, 8-18 and 6-15 MW/day for RDF process; and 17-35, 16-32 and 11-28 MW/day for plasma arc gasification process respectively. The lower values in these ranges depict the energy generation potential for segregated waste while the higher values are for the bulk waste. These values are based on theoretical ideals and help in identifying the optimal WTE technique. © 2013 Elsevier Ltd. All rights reserved.
Assessment of environmental gene tags linked with carbohydrate metabolism and chemolithotrophy associated microbial community in River Ganga
(Elsevier B.V., 2019) Bhaskar Reddy; Jitendra Pandey; Suresh Kumar Dubey
The microbial community mediated biogeochemical cycles play important role in global C-cycle and display a sensitive response to environmental changes. Limited information is available on microbial composition and functional diversity controlling biogeochemical cycles in the riverine environment. The Ganga River water and sediment samples were studied for environmental gene tags with reference to carbohydrate metabolism, photoheterotrophy and chemolithotrophy using high throughput shotgun metagenomic sequencing and functional annotation. The diversity of environmental gene tags specific microbial community was annotated against reference sequence database using Kaiju taxonomic classifier. The metagenomic analyses revealed that the river harbored a broad range of carbohydrate and energy metabolism genes. The in-depth investigation of metagenomic data revealed that the enzymes associated with reverse TCA cycle, Calvin-Benson cycle enzyme RuBisCO, starch and sucrose metabolism genes were highly abundant. The enzymes associated with sulfur metabolism such as EC:2.7.7.4 (sulfate to ammonium per sulfate), EC:1.8.1.2, EC:1.8.7.1 (sulfite to H 2 S) were prevalent in both the class of samples. The principal component analysis of the functional profiles revealed that the water and sediment samples were clustered distinctly suggesting that both the sites had variable abundance of functional genes and associated microbiota. The taxonomic classification showed abundance of Proteobacteria, Actinobacteria and Bacteroidetes phyla. Also, the metagenomic study showed the presence of purple sulfur bacteria viz. Thiodictyon, Nitrosococcus and purple non-sulfur bacteria viz. Bradyrhozobium and Rhodobacter. The study demonstrates that the Ganga River microbiome has prevalence of functional genes involved in carbohydrate anabolism and catabolism, and CO 2 fixation with great prospects in cellulose and sulfide degrading enzyme production and characterization. © 2019
Assessment of groundwater quality with special emphasis on nitrate contamination in parts of Varanasi City, Uttar Pradesh, India
(Springer Verlag, 2018) Arif Ahamad; Sughosh Madhav; Pardeep Singh; Jitendra Pandey; A.H. Khan
In the current study, an effort was made to assess the geochemistry of groundwater by random collection of the samples from 15 different borewells located in various parts of Varanasi City, Uttar Pradesh, India. Geology of the study region is dominated by Quaternary alluvial sediments of Pleistocene to recent times where the younger alluvium receives fresh deposits of silt, clay and loam from periodic flood events. Ca–Mg–HCO3was inferred as major hydrogeochemical facies from Piper trilinear diagram. Ca–Mg type and HCO3− type were the dominating cation and anion facies, respectively. Hydrogeochemistry reveals that the cation abundance follows the order Na+> Mg2+ > Ca2+ > K+ and anion abundance HCO3− > Cl− > NO3− > SO42− > F−. As per Gibb’s plot, chemical weathering of rock minerals is affecting the quality of groundwater. Overall, most of the samples for majority of parameters lie within the allowable limits as set by WHO (guideline for drinking water quality, fourth edn, WHO, Geneva, p 340, 2004) except nitrate, which varied in the range of 40.32–78.97 mg/l. 80% of the groundwater samples in which nitrate exceeded beyond acceptable limit (50 mg/l), as per WHO standard, which may be due to poor sewerage, human excreta leakage from septic tanks, poorly maintained disposal of solid waste locally, agricultural activities, wastewater irrigation and irrigation runoff. The Water quality index (WQI) value of the study region depicts that 93% samples lie in the category of excellent water and 7% in good water category. Good positive correlation of NO3–Cl (r = 0.60) and Na–NO3 (r = 0.55) signifies an anthropogenic input of these ions into the subsurface water of the study region. The various indices such as electrical conductivity (EC), salinity, percent sodium, sodium absorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), Kelly’s ratio and magnesium ratio are used to check the fitness of ground water for irrigation uses which shows that groundwater samples of the study region is good to permissible for agricultural uses. © 2018, The Author(s).
Assessment of heavy metal pollution in water and surface sediment and evaluation of ecological risks associated with sediment contamination in the Ganga River: a basin-scale study
(Springer Verlag, 2019) Ekabal Siddiqui; Jitendra Pandey
We investigated eight heavy metals (Cr, Cd, Cu, Ni, Pb, Zn, Mn, and Fe) in water and bed sediment at 9 study sites along with 2320 km stretch of the Ganga River. Principal component analysis (PCA) and indices such as geo-accumulation index (I geo ), contamination factor (CF), enrichment factor (EF), pollution indices, and sediment quality guidelines were used to assess source apportionment and magnitude of contamination. Concentrations of Cr, Cd, Pb, Ni, Cu, and Fe in water have exceeded their respective standards in the middle and lower reaches of the river. Sediment Cr and Ni have reached probable effective concentration (PEC) at Kannauj, imposing likely threats to sediment dwellers. Highest I geo values were recorded for Cr, Cd, and Pb at Kannauj, Rajghat, and Howrah. We further tested ecological risks (E r ) and potential ecological risks (PERI) to assess individual and cumulative effects and found the Kannauj, Rajghat, and Howrah sites under the high-risk category. The modified pollution index (MPI) and the modified degree of contamination (mCd) also revealed the middle and lower river reaches under moderately to the heavily polluted category. Our study provides the first detailed watershed-scale database on heavy metal concentration in water and bed sediment, the magnitude of contamination, and likely ecological risks to aquatic organisms in the Ganga River. Given that the Ganga water is used for drinking and irrigation and the river harbors a diversity of habitats for fisheries, the study merits attention from a human health perspective as well. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.
Atmospheric deposition and land-surface runoff driven nutrient flushing in Ganga River (India)
(Taylor and Francis Ltd., 2020) Jitendra Pandey; Usha Pandey; Anand V. Singh; Deepa Jaiswal; Ekabal Siddiqui; Kavita Verma
Disproportionate addition of nutrients can alter the nutrient stoichiometric balance of surface water bodies. In the present study, we investigated the atmospheric deposition (AD) and runoff-induced nutrient enrichment and N:P stoichiometric shifts in the Ganga River along a 35 km stretch of Varanasi city. The region receives 8–42 kg ha−1 of reactive-N (NO3− + NH4+) and 0.40–3.10 kg ha−1 of PO43- through AD annually. The most polluted Rajghat Site receives ~770.50 tons of reactive-N (Nr) and ~64.50 tons of PO43- annually as AD input in the sub-watershed; and ~25.10 tons of Nr and 2.09 tons of PO43- directly on the water surface. Concentrations of nutrients in surface runoff increased with AD input irrespective of land use. Among land use categories, the runoff nitrate was highest from agricultural catchment while NH4+ and PO43- were highest from urban areas. The study showed that the AD-runoff coupled with additional supplies could substantially alter the overall load and stoichiometric ratios of critical nutrients with a consequent effect on ecological functioning of the river in long-run. © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
Atmospheric deposition coupled terrestrial export of organic carbon in Ganga River (India): linking cross-domain carbon transfer to river DOC
(Springer Verlag, 2015) Jitendra Pandey; Anand V. Singh; Rachna Singh; Pooja Kaushik; Usha Pandey
The atmosphere–land–water connectivity of dissolved organic carbon (DOC) is not altogether accounted in major rivers of India despite recent researches highlighting its importance. We studied the coupled effect of atmospheric deposition (AD) and local land use on DOC buildup in Ganga River for a period of 6 years. The AD-OC input increased consistently over time and there was over 1.5- to 1.8-fold increase in 2012 relative to 2007. Microbial activity and water soluble organic carbon (WSOC) in sub-catchment and DOC in land surface runoff increased consistently over time along the gradient of AD input. The river DOC showed positive correlation (R2 = 0.24–0.84; p < 0.001) with AD-OC and runoff DOC and WSOC showed positive correlation (R2 = 0.96; p < 0.001) with soil microbial activity. Principal component analysis segregated study sites into four groups demarcating source relationships. Our study, that forms the first report on atmosphere–land–water transfer of organic carbon in Ganga River, suggests that future climate models should include region-specific time series data on changing state of atmosphere– land–water connectivity and associated shift in carbon balance of major rivers for more accurately predicting the climate change drivers. © 2015, The Author(s).
Atmospheric deposition of nutrients shifts carbon capture and storage trends in freshwater tropical lakes in India
(Biotron Institute, 2014) Jitendra Pandey; Usha Pandey
An understanding of ongoing changes in biogeochemistry of carbon (C) as influenced by increasing atmospheric deposition (AD) of nutrients is important for integrated water resource management and for exploring options for balancing C sink and fluxes. To determine whether AD-nutrients would increase phytoplankton production and catchment carbon flushing in lakes, we analyzed NO3-, NH4+ and PO4-3 in atmospheric deposits, microbial biomass and activity in catchment, nutrient and dissolved organic carbon (DOC) in runoff and, phytoplankton production and sediment-C in six freshwater lakes from 1999 to 2008. Although N: P stoichiometry of AD did not change over time, there was over 1.5 fold increase in AD-NO3-, NH4+ and PO4-3overtime. Microbial biomass and activity in catchments and, DOC and nutrients in runoff increased consistently over time. Lake nutrients, DOC, gross primary productivity, chlorophyll a biomass and sediment-C also showed positive relationship with AD-nutrients. The study indicates that rising input of AD-nutrients steer freshwater lakes towards greater productivity, whereas such inputs in catchment enhance microbial processes and consequently runoff DOC flush and the-coupled effects of these may cause long-term shift in water quality and C balance of these ecosystems.
Atmospheric Deposition: An Important Determinant of Nutrients and Heavy Metal Levels in Urban Surface Runoff Reaching to the Ganga River
(Springer, 2022) Ekabal Siddiqui; Jitendra Pandey
Excessive loading of water bodies with surface runoff-driven nutrients and heavy metals has become a serious concern worldwide. We investigated the surface runoff quality for nutrients and heavy metals being flushed to the Ganga River, as influenced by atmospheric deposition (AD). We selected three city sites in India, Haridwar, Varanasi, and Howrah, which differ widely with respect to population density and anthropogenic activities. We found distinct spatio-temporal trends in AD input of nutrients and heavy metal with values being highest in Varanasi region followed by Howrah and Haridwar. The runoff nutrients and metals showed strong synchrony with their respective levels in AD input. The concentrations were higher in the first flush. We found strong correlations (R2 = 0.83–0.93; p < 0.001) between AD metals and nutrients with their respective concentration in runoff. For all the studied metals, except Cd, the major proportions were in particulate form. The Cd was present in almost equal proportions in particulate and dissolved fractions. Metals in runoff were found in order as: Zn > Pb > Cu > Ni > Cr > Cd. In general, the concentrations of metals were higher than those reported in other studies. The contamination factor and geo-accumulation index show that the Cd was a major pollutant in the runoff. The pollution load index (PLI) indicates that all three sites are highly polluted. Our study indicates that there is a need to reduce particulate loads. Furthermore, because of the high concentrations of pollutants in the first flush, strategies may be developed to enhance the efficiency of treatment of the first flush of runoff. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Benthic hypoxia in anthropogenically-impacted rivers provides positive feedback enhancing the level of bioavailable metals at sediment-water interface
(Elsevier Ltd, 2020) Deepa Jaiswal; Jitendra Pandey
We investigated the effect of hypoxic-anoxic range of dissolved oxygen (DO) on metal release/bioavailability at sediment-water interface (SWI) in the Ganga River. Here, we consider eight sites in the main river stem along 518 km; sixty sites downstream two point sources and two tributary confluences covering 630 km; and an incubation experiment to verify these results. We found higher concentrations of metals and bioavailable fractions at SWI at two locations of main stem and up to 700 m, 1000 m, 400 m and 500 m downstream Assi drain, Wazidpur drain, Ramganga confluence and Varuna confluence respectively where DO at SWI (DOsw) was <2.0 mgL−1. The incubation experiment did show higher levels of metal- and P-release and bioavailability under anoxic-hypoxic range of DO. The risk assessment code and eutrophication index indicated high to very high risks of contaminated river sediment and water to aquatic environment at sites with hypoxic-anoxic range of DOsw. Further, the principal component analyses separated metals and bioavailable fractions opposite to FDAase indicating greater risk at these locations. The study, which forms the first report on benthic hypoxia/anoxia-driven metal release, potential bioavailability and risk to the Ganga River ecosystem will help understanding how human-driven perturbations influence geochemical cycling of metals and ecosystem responses in large rivers. This study forms first report on benthic hypoxia/anoxia-driven sediment-metal release/bioavailability and associated shifts in ecosystem response of the Ganga River. © 2019 Elsevier Ltd
Carbon dioxide emission and its regulation at land–water interface downstream of a point source at Ganga River (India)
(Blackwell Publishing Ltd, 2018) Deepa Jaiswal; Ekabal Siddiqui; Kavita Verma; Jitendra Pandey
The streams and rivers are considered hotspots of CO2 exchange; and representative direct CO2 emission measurements are essential for a correct regional estimate. We measured CO2 emission flux at 15 sites at land–water interface downstream of a point source during low flow for three consecutive months for the year 2017. The general range of CO2 efflux observed here was close to the results of regional studies, although values near the point source were disproportionately high (>350 mg/m2/h). CO2 emission flux showed strong dependence on total organic carbon (TOC; R2 = 0.96; P < 0.001), NH+ 4 (R2 = 0.88; P < 0.001), soluble reactive-P (SRP; R2 = 0.91; P < 0.001) and microbial activity measured in terms of fluorescein diacetate activity (FDAase; R2 = 0.92; P < 0.001) and substrate induced respiration (SIR; R2 = 0.96; P < 0.001). Because point source-associated interfaces provide heterogeneous habitats, our study suggests the need for large scale monitoring of CO2 emission at land–water interface of major rivers for more correctly presenting the regional scale CO2 budget. © 2018 CIWEM
Carbon dioxide emission coupled extracellular enzyme activity at land-water interface predict C-eutrophication and heavy metal contamination in Ganga River, India
(Elsevier B.V., 2019) Deepa Jaiswal; Jitendra Pandey
Ganga, the largest river system in India, has fundamental ecological and social values; and has a large number of monitoring and assessment programs, but is rarely considered to explore the ecological response indicator(s) to identify anthropogenic environmental impacts. This study was targeted to identify a sensitive response indicator that can be used to detect ecosystem changes, on appropriate spatial and temporal scales, as a result of anthropogenic impacts. Intensive sampling was conducted during summer low flow of two consecutive years (2017–2018) on a sub-set of eight study sites along with 518 km main stem; and thirty sites downstream two point sources (one at the mouth and 14 up to 1.4 km downstream each point source). The study shows that CO2 emission at the land-water interface (LWI) can be used as one of the most robust response predictors of C-eutrophication. This predictability, however, is masked at sites containing a high concentration of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn). The total concentration of heavy metals (∑THM ranged from 161.12 to 887.04 μg g−1) and their total bioavailable fractions (∑TBF ranged from 49.96 to 611.71 μg g−1) indicated moderate to high degree of pollution load. The regulatory role of total organic carbon (TOC) to CO2 emission decreased as the metal concentrations tended to increase. The dynamic fit curve of main stem data showed that ∑THM > 347.44 μg g−1 is able to cause detrimental effects on microbial activity and CO2 emission, however, for the site with very high TOC concentration (Asdr mouth) this limit reached to 472.53 μg g−1 indicating the modulatory role of TOC in metal toxicity. Passing from low to high concentrations, a gradual reduction in FDAase, β-D-glucosidase, and protease was observed, and at ∑TBF of 611.71 μg g−1, the FDAase (a measure of overall microbial activity) declined by over 5.34 folds compared to those at ∑TBF of 49.96 μg g−1, the minimal level observed in this study. Our study gives a snapshot of a large river identifying, for the first time, the CO2 emission coupled extracellular enzyme activities at LWI as a ‘response’ predictor of C-eutrophication and potential consequences of heavy metal contamination. © 2018 Elsevier Ltd
Cereals and Phytohormones Under Salt Stress
(Springer Nature, 2022) Varunendra Kumar Singh; Sakshi Pandey; Nidhi Verma; Madhulika Singh; Jitendra Pandey; Sheo Mohan Prasad
Cereal crops are occupying a dynamic part in nourishing the whole population of the world. The development and production of these cereal crops are poorly affected when exposed to different environmental abiotic stresses, among which salinity stress plays a major role. Plants that respond to salt stress involve various complex physiological, molecular, as well as biochemical changes in the plant system. Phytohormones play a crucial role in acquiring some adaptational reactions in a plant's system when exposed to salinity. Gibberellins (GAs), ethylene (ET), cytokinins (CKs), salicylic acid (SA), jasmonates, abscisic acid (ABA), and brassinosteroids (BRs) are important plant hormones that respond to salinity stresses via their signalling attributes. The cellular disturbances caused by salinity stress are potentially removed by exogenous phytohormones in plants. Phytohormones extensively regulate some specific genes to deal with saline conditions. In this chapter, the collective information is mentioned which is focused on the role of phytohormones along with the involved genes in the alleviation of salinity stress in cereal crops. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022
Challenges and knowledge gaps in ecological sciences
(Indian Academy of Sciences, 2018) Suresh Kumar Dubey; Jitendra Pandey
[No abstract available]