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Acacia auriculiformisis an agro-forestry species in India with application in paper industry. The species is saline intolerant and fails to establish. Experiments were conducted to induce saline tolerance in callus cultures ofA. auriculiformison Murashige & Skoogs medium supplemented with different concentrations of NaCl+CaCl2–––(2:1; 50, 100, 150, 200, 250 or 300 mM). Calli were trained for eight sub-culture generations. The genome from saline-tolerant calli was extracted by modified cetyl trimethyl ammonium bromide method and subjected to polymerase chain reaction-based random amplified polymorphic DNA technique. The polymorphic DNA bands were eluted and cloned toEscherichia coliwith the help of pTZ57R/T. The transformed plasmid DNA was sequenced and subjected to BLAST at National Center for Biotechnology Information. Results indicated that saline training of calli resulted in the expression of tolerance to 100 and 150 mM saline concentration after eight sub-cultures. Both the saline concentrations produced conspicuous bands in trained calli. Three nucleotide sequences were similar to those ofBacillus amyloliquefacienssub sp.plantarumand BLAST search result indicated high homologies to ThiT thiamine transporter, YuaG flottilin type band 7, and U32 class peptidase protein genes in bacterial genome. The annotation of these protein genes in saline tolerance was discussed. The study suggested that the endophyticB. amyloliquefacienssub sp.plantarummight be inducing saline tolerance inA. auriculiformis. [ABSTRACT FROM AUTHOR]

This paper describes the existence of high salinity in an inland aquifer system of a limited extent located in the granitic terrain of south India. Salinity levels observed in 55 water samples collected pre- and post-monsoon are discussed. Limited repeat sampling during the two seasons shows no significant change in hydrochemistry, probably due to the prevailing drought conditions during the study period (2017–18). As per the salinity classification based on total dissolved solids (TDS), only one sample indicates freshwater while ~ 40% of the samples are slightly saline, and the remaining have moderate salinity. All the high TDS samples are located over a limited area, and most show the water type as Ca–Mg–Na–Cl–SO4. Hydrochemical data indicate a gradual increase in salinity from west to east. Mainly two distinct processes (1) reverse ion exchange and (2) evaporation are likely to have influenced the groundwater chemistry. Variation in water chemistry between granite and gneiss formations indicates the influence of geology on hydrochemistry. Insignificant changes in hydrochemistry for the limited repeat sampling during pre and post-monsoon periods show a meagre recharge due to failed monsoon. However, depleted stable isotope values with reference to high TDS suggest faster recharge conditions in the granitic region than in the gneissic region. Accumulation of high salinity in the groundwater is restricted to the granitic area. We postulate that the presence of Hornblende Biotite Gneiss along the southern parts of the granitic region may be acting as a boundary for accumulating saline groundwater in a limited area in this region. However, it needs confirmation through further detailed geological and geophysical studies. [ABSTRACT FROM AUTHOR]

Developed coastal regions are the hotspots for contaminated groundwater discharge, affecting sensitive marine ecosystems. The present study aims to identify submarine groundwater discharge (SGD) locations and quantify the contaminant load reaching to the western coast of India (Gujarat coast) using stable isotopes, seepage meter, heat and solute transport model. The coastal aquifers are highly enriched in trace metals due to various active natural processes and anthropogenic activities across the coast. Terrestrial and recirculated SGD was a significant contributor to flow and metal load, which ranged from 1.04 to 181.1 m 3 .year -1 and 0-77.41 kg.year -1, respectively. The highest estimated SGD in the Gujarat coast was relatively less than the SGD reported in the Bay of Bengal and comparable to the South Chennai coast. The order of metal flux found in the study was Zn > Fe > Cr > Pb > Ni > Cu > Mn, whereas the highest flux of Zn (77.41 kg. year -1 ) was reported at Fansa beach, which was 7x Fe-flux and 45 x Cr-flux, respectively. Higher micronutrients (Fe and Zn) load in the southern coast leads to increased vulnerability of eutrophication, algal blooms and biotic ligand formation in aquatic species. This enrichment of micronutrients in the coastal ecosystem was evident by the growth of seaweeds on the seabed at SGD identified locations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Salinity is an environmental phenomenon that affects the world's arid and semi-arid regions, where it causes soil degradation and problems for agriculture. Salinity began to attract serious attention in the irrigated districts of the Murray Valley in south-eastern Australia in the 1960s. However, observations that the south-eastern Australian landscape was affected by naturally occurring salts predates this period of awareness by more than half a century. Drawing on documentary history, the present paper reveals what soil chemists in New South Wales in the 1890s already understood of the potential dangers of salinity. These scientists were aware of the experience of their colonial colleagues in British India, where the seriousness of the problem had been recognised by the 1870s. Using evidence from India and south-eastern Australia in the nineteenth and early-twentieth centuries, the paper outlines the opposing worldviews of scientists and engineers in New South Wales about the potential dangers of intensive irrigation. It offers an explanation as to why that understanding was insufficient to prevent the growth of the problem. [ABSTRACT FROM AUTHOR]

In response to abundant freshwater input from rainfall and river discharge, the northern Bay of Bengal (BoB) is featured by low sea surface salinity (SSS) and strong intraseasonal variability (ISV). This study investigates the characteristic and dynamic mechanisms of SSS ISV in the northern BoB based on satellite observations and the output of Simple Ocean Data Assimilation (SODA). The strong SSS ISV is mainly concentrated near the mouth of the Ganges–Brahmaputra River and along the east coast of India, where the horizontal salinity gradient varies greatly. SSS ISV in the northern BoB is notably in phase with freshwater transport, which peaks from July to November. The contribution of riverine freshwater is significant both geographically and temporally. The SSS budget analysis indicates that the horizontal advection plays a dominant role in SSS ISV. Once currents cross the salinity field, large horizontal advection anomalies become important and favor SSS ISV. Altered SSS patterns can impact water density, potentially influencing the strength and direction of currents. This, in turn, may have cascading effects on local and regional climate patterns. [ABSTRACT FROM AUTHOR]

India has a power capacity of 4,02,817 MW, with over half coming from coal-based thermal power plants like the Kolaghat Thermal Power Plant (KTPP), West Bengal, India. These plants produce harmful fly ash, requiring safe disposal. KTPP alone generated 0.5921 million tons of fly ash in 2020-21, managed using ash ponds. Concerns have arisen regarding contamination of nearby agricultural fields, impacting rice cultivation. The objective of the study was to understand how fly ash affects soil and seed germination and emphasizes the importance of making careful decisions when using industrial residues in agriculture to ensure sustainable and responsible practices that prioritize environmental health and plant well-being.Samples were collected from areas near KTPP, and plant growth substrates were prepared by mixing control soil with varying fly ash concentrations. The study was conducted between 15 February and 19 May 2023 in PnaskuraBanamali College (Autonomous), Purba Medinipur, West Bengal, India. The physical and chemical properties of these substrates were analyzed, and rice seed germination studies were carried out over 30 days. The subsequent transplantation and growth assessments included measuring shoots and roots, analyzing leaf chlorophyll and carotenoids, and conducting statistical evaluations. The experiments were triplicated, and statistical analyses using SPSS 16 indicated statistical significance at p < 0.05.The study helps to understand how fly ash affects soil and seed germination, revealing both positive and negative effects on soil properties and plant growth. It emphasizes the need for careful decision-making when using industrial residues in agriculture to ensure sustainable and responsible practices that prioritize both environmental health and plant well-being. [ABSTRACT FROM AUTHOR]

Previous studies have hypothesized that climatologically thick salinity-stratified barrier layers (BLs) in the north Indian Ocean (NIO) influence the upper ocean heat budget, sea surface temperature (SST), and monsoons. Here, we investigate how state-of-the-art Coupled Model Intercomparison Project phase 6 (CMIP6) climate models simulate the NIO barrier layer thickness (BLT). CMIP6 models generally reproduce the BLT seasonal cycle and spatial distribution, but with shallow November–February (NDJF) biases in regions with thick observed BLT: the eastern equatorial Indian Ocean (EEIO), Bay of Bengal (BoB), and southeastern Arabian Sea (SEAS). We show that the intensity of the CMIP6 equatorial easterly wind bias controls the EEIO shallow isothermal layer depth (ILD) and BLT biases. It also controls the BoB shallow BLT bias, both through the propagation of the EEIO shallow ILD bias into the NIO coastal waveguide and because it is linked to the BoB dry and cold bias through the Bjerknes feedback, hence also controlling the mixed layer depth (MLD) deep bias there. Finally, the SEAS shallow BLT bias is due to a too-deep MLD, in response to subdued monsoonal currents around India, which do not bring enough BoB low-salinity water. The BL insulating effect mentioned in literature does not seem to dominate in CMIP6. Rather, the CMIP6 salinity-related deep MLD biases diminish the BoB cooling rate by winter upward surface heat fluxes, reducing cold SST biases. This suggests that salinity effects alleviate the easterly equatorial wind, cold, and dry BoB biases that develop through the positive Bjerknes feedback loop in CMIP6. [ABSTRACT FROM AUTHOR]

Aggressive cultivation practised across the Indian subcontinent to meet the growing food demands results in the groundwater at many places being severely affected by salinity, and this is a recognised hazard of agricultural belts. Evaluating spatial variations of salinity hazards is important for managing agricultural activity and implementing suitable and timely remedial measures. A precise representation of spatial variations of groundwater salinity using electrical conductivity (EC) can help identify potential sources and evaluate their severity and spatial impact. Simple spatial interpolation schemes, viz., inverse distance weighted (IDW) and trend surface analysis (TSA) are evaluated with over 250 EC measurements in groundwater during two seasons from saline-impacted regions of northwest India. Considering the three performance metrics, namely, correlation coefficient, root mean square error and mean absolute error, IDW scheme was adjudged better than TSA for both seasons. Interpolation by TSA and contour plot using OriginLab® software resulted in unrealistic (negative) values of EC, whereas IDW was free from such limitations. Errors associated with IDW-based interpolated EC values for this site would be 320–415 μS/cm for pre-monsoon and 630–800 μS/cm during post-monsoon seasons. Refined EC map generated using seasonal IDW interpolation scheme would facilitate timely and cost-effective remediation of salinity hazard, impact assessment of point and non-point sources on salinity hazard. Research highlights: Simple algorithms were examined for spatial interpolation of groundwater EC; IDW was adjudged better over TSA. Seasonal influence on interpolation parameters for EC was highlighted. IDW parameters ascertained from systematic search in this study are different from reported default values in commercially available software. Whereas TSA or default interpolation with OriginLab® resulted in negative(unrealistic) EC values, IDW results were consistent. Refined EC map generated using seasonal IDW interpolation scheme would facilitate: timely and cost-effective remediation of salinity hazard; impact assessment of point and non-point sources on salinity hazard. [ABSTRACT FROM AUTHOR]

The present study led to setting up a grid-based soil fertility map along with the best fit model in the coastal regions based on soil physical (coarse, sand, silt, clay, bulk density), chemical (CEC, pH, and soil organic carbon), topographic (elevation), and nutrient elements (P2O5, K2O, Na, Zn, B) in the active Ganga deltaic region of Sundarban Biosphere Reserve, India. Soil samples have been collected from 30 soil grids, and 0–15 cm soil depth was preferred for fertility analysis because most essential soil chemical and nutrient elements affecting soil fertility are concentrated in this depth range. We have used the fuzzy-AHP-Delphi (FAHP) and fuzzy logic-Delphi (FL) methods to determine the soil fertility zone. The rules are generated on the MATLAB interface in the text form; the words "IF," "THEN," "IS," "AND," etc., are used to complete the mode-building process. The weights and the desirable limits for each criterion were set based on the expert opinions and existing literature. The kriging interpolation method and natural break classification were used to represent the soil fertility maps into five classes, namely very high fertility (0.80–1.0), high fertility (0.60–0.80), moderate fertility (0.40–0.60), low fertility (0.20–0.40), and very low fertility (0.00–0.20) respectively. Both the models show that soil fertility is respectively higher near the Hooghly River bank. In many cases, the results obtained from FAHP and FL are quite similar but huge dissimilarity has been noticed in grid numbers G2, G3, G4, F1, and F2. Since the FAHP method has been used for the weight of each criterion, therefore, it only prefers those more important parameters over others. The overall accuracy of the soil fertility map was 82.16% for the fuzzy logic model, and 79.62% for the FAHP model and the kappa coefficient value was determined as 0.82 for the fuzzy logic model and 0.79 for the FAHP model. The soil fertility map was validated using the success rate curve under the ROC technique, and the area under curve (AUC) was calculated as 84.02% for the fuzzy logic model and 81.60% for the FAHP model. Since the standard limits for each criterion were known, therefore, fuzzy logic was found to best fit the model for analyzing soil fertility for each grid. [ABSTRACT FROM AUTHOR]

This paper deals with a systematic hydrogeological, geophysical, and hydrochemical investigations carried out in SIPCOT area in Southern India to demarcate groundwater pollution and saline intrusion through Uppanar River, which flows parallel to sea coast with high salinity (average TDS 28, 870 mg/l) due to back waters as well as discharge of industrial and domestic effluents. Hydrogeological and geophysical investigations comprising topographic survey, self-potential, multi-electrode resistivity imaging, and water quality monitoring were found the extent of saline water intrusion in the south and pockets of subsurface pollution in the north of the study area. Since the area is beset with highly permeable unconfined quaternary alluvium forming potential aquifer at shallow depth, long-term excessive pumping and influence of the River have led to lowering of the water table and degradation of water quality through increased salinity there by generating reversal of hydraulic gradient in the south. The improper management of industrial wastes and left over chemicals by closed industries has led surface and subsurface pollution in the north of the study area. [ABSTRACT FROM AUTHOR]

The biochemical composition of red seaweeds, Catenella repens was investigated in this present study along with subsequent analysis of relevant physico-chemical variables. In this study, the relationship between the nutritive components of this species and the ambient environmental parameters was established. Protein content varied from 2.78 ± 0.30% of dry weight (stn.3) to 16.03 ± 0.96% of dry weight (stn.1) with highest values during monsoon. The protein levels were positively correlated with dissolved nitrate content and negatively correlated with water temperature (except stn.3) and salinity. Carbohydrate content of this species varied significantly (p < 0.05) during pre-monsoon between stations and the values showed positive relationship with salinity and surface water temperature. In contrast to carbohydrate, lipid concentration was lowest in values and varied very slightly between seasons and stations. Astaxanthin content of the seaweed species was greater in pre-monsoon than monsoon and post-monsoon in all the selected stations. Compared with the three seasons, samples of red seaweed collected in pre-monsoon has high carbohydrate-astaxanthin in contrast to protein-lipid which showed high values during monsoon. Statistical analysis computed among the environmental and biochemical parameters suggests the potential role played by the abiotic parameters on biosynthetic pathways of seaweed. This paper also highlights the influence of the nutritional quality of water that can be used for mass cultivation of Catenella repens. [ABSTRACT FROM AUTHOR]

Hydrochemical study had been carried out on the groundwater resources of Potharlanka Island, Krishna delta, India. Groundwater samples were collected and analyzed at 42 sites in December 2001 and October 2006. A comparative study of hydrochemical data indicates: groundwater is mildly alkaline with a pH of 7.0–8.2; electrical conductivity (EC) varies from 605 to 5,770 μS/cm in December 2001, and 652–5,310 μS/cm in October 2006. More than 62% of the groundwater samples in 2006 have TDS value <2,000 mg/l, which is within permissible limit of potable water, but 57% of the samples in 2001, are higher than the maximum permissible limit. Extremely low HCO3/Cl and variable high Mg/Ca (molar ratios) had been indicated the transformation of the fresh groundwater aquifer systems to saline in 2001. Groundwater of this Island is mainly classified as Na–Cl and mixed types. A high percentage of Na–Cl type of these waters indicates the possibility of seawater ingression/intrusion process during 2001 and comparatively mixed water type indicates the dilution activities of groundwater. Excessive withdrawal of groundwater has caused the increase of saline water intrusion. Improvement of groundwater quality in this Island due to artificial recharge structures made by NGRI under RGNDWM project and affects of the flood due to heavy rainfall of the months of September–October 2005 are discussed in this paper. [ABSTRACT FROM AUTHOR]

Chilika Lagoon (19°28′-19°54′N, 85°06′-85°36′E), on the Orissa coast, India, is one of the world's unique ecospheres. It is the largest brackish water lagoon with estuarine character. Because of its rich biodiversity and socioeconomic importance, it was designated as a "Ramsar site"--a wetland of international importance--in 1981. Interest in detailed analysis of the circulation, biotic, and abiotic factors affecting the lagoon and its limnology is a result of the opening of the new mouth on 23 September 2000 to resolve the threat to its environment from various factors--eutrophication, weed proliferation, siltation, industrial pollution, and depletion of bioresources. This paper describes the development of a two-dimensional depth-averaged hydrodynamic model for Chilika Lagoon and the resulting simulation of currents and salinity corresponding to (i) the Southwest and Northeast monsoon seasons and (ii) pre- and post-mouth-opening conditions. Numerical experiments are performed to understand the different factors--wind, tides and freshwater influx--and their independent and collective roles. Comparison of results obtained with one or both of the openings is made to quantify and validate the changing salinity pattern, which has improved the productivity of the lagoon. Our study shows the salinity levels to be much lower during the southwest monsoon compared to the northeast monsoon, which is validated by observations. The decrease in salinity is attributed to more freshwater influx during the southwest monsoon. There is a significant increase (14%-66%, depending on the sector) in salinity after opening of the new mouth, the maximum change being observed in the channel that connects the lagoon to the sea. The constriction in the lagoon that blocks the tidal effects entering the lagoon is found to be responsible for maintaining the main body of the lagoon with low salinity. The dynamic model will be an important input for our on going work in seasonal study of the ecology of Chilika Lagoon. [ABSTRACT FROM AUTHOR]

This paper reviews the past and present conditions and management of Chilika Lagoon, the largest lagoon on India's eastern coast. Spatial and temporal salinity gradients, because of freshwater river inflow and seasonal seawater influx, have created unique characteristics of an estuarine ecosystem, and exercised a continuous, selective influence on the biota. Unfortunately, its biodiversity and the livelihoods that depend on it were being lost at a fast rate because of a blockage of the lagoon's mouth by silt coming from upstream catchments, as well as oceanic long-shore transport. Projects to restore the dynamic characteristics of the lagoon included dredging a new mouth to the ocean, as well as prevention of soil erosion in upstream areas. Management efforts resulted in a dramatic revival of this ecosystem, and contributed to a sharp rise in the incomes of fisherfolk. The institutional aspects of implementing such large-scale policy changes also are discussed, and the remaining issues and lessons learned are presented. [ABSTRACT FROM AUTHOR]

In the irrigated areas of semi-arid regions, especially in northwest India, a considerable recharge to the groundwater leads to waterlogging and secondary salinization. In several sub-areas groundwater is mined, water tables fall, and salts are added to the root zone because a high proportion of irrigation water is derived from pumped groundwater of poor quality. Out of 1 million hectares of irrigation induced waterlogged saline area in northwest India, approximately half a million hectares are in the state of Haryana. Taking a homogenous physical environment as a starting point, the way and the extent to which farmers’ activities will affect the salinity and sodicity situation depend on farming and irrigation practices. In the past, soil salinity was mainly associated with high groundwater tables, which bring salts into the root zone through capillary rise when water is pumped. But nowadays, increasing exploitation of groundwater for irrigation purposes has led to declining groundwater tables and a threat of sodification and salinization due to use of poor quality groundwater. Farmers in northwest India are facing a situation in which they have to deal with salt volumes that are harmful for water uptake of crops. They are also facing the problem of sodicity, which has an adverse effect on the physical structure of the soil, causing problems of water intake, transfer and aeration. To mitigate the adverse effect of soil salinity on crop yield, the farmers irrigate frequently, either mixing canal water and groundwater, or alternately using canal water and groundwater. Due to differences in environmental parameters in the farming systems, such as groundwater quality, soil types and uneven distribution of irrigation water, income losses to the farming community are not uniform. This paper highlights the economic loss due to environmental degradation through the twin problems of waterlogging and soil salinity, which threaten the sustainability of agricultural production in Haryana state. Our analysis shows that the net present value of the damage due to waterlogging and salinity in Haryana is about Rs. 23,900/ha (in 1998–1999 constant prices). The estimated potential annual loss is about Rs. 1669 million (about US$ 37 million) from the waterlogged saline area. The major finding of the paper is that intensification per se is not the root cause of land degradation, but rather the policy environment that encouraged inappropriate land use and injudicious input use, especially excessive irrigation. Trade policies, output price policies and input subsidies all have contributed to the degradation of agricultural land. [Copyright &y& Elsevier]

Globally, small temporarily closed estuaries are the least considered for fisheries assessment and management due to a low scientific priority and regional importance. However, these ecosystems are highly exposed to anthropogenic pressures and may deteriorate without assessing its aquatic resources. In this study, fish diversity and guild structure of Chettuva—a temporarily closed tropical estuary in the western coast of India—was investigated. A total of 70 fish taxa belonging to 32 families were recorded with the quantitative predominance of families; Mugilidae, Cichlidae, and Leiognathidae. Family Carangidae had the highest species diversity (seven species), followed by Clupeidae and Mugilidae (five species). Ecological guild assessment revealed that the immigrating marine fish species (marine estuarine opportunist (34 species) and marine estuarine dependent (13 species)) dominated the guild structure over the estuarine resident species (seven species). The marine species were found all along the saline gradient and throughout the sampling period indicating the salinity ingress towards the estuarine zone throughout the year. Carnivores and omnivores were the major feeding mode functional guilds in terms of diversity, whereas detritivores dominated in numerical abundance throughout the salinity gradient. The major environmental drivers of the fish assemblages in the estuary were salinity and chlorophyll a. The distribution of freshwater fishes and estuarine resident species was connected with the rising primary productivity as the majority of fishes rely on the algae for feeding, whereas marine estuarine dependent and marine estuarine opportunist species occurred in areas with the highest salinity concentrations. [ABSTRACT FROM AUTHOR]

Previous studies suggest that the winter surface freshening in the southeastern Arabian Sea (SEAS) contributes to the development of very high Sea Surface Temperatures (SST) thereby influencing the following summer monsoon onset. Here, we use forced and coupled simulations with a regional ocean general circulation model to explore the SEAS Sea Surface Salinity (SSS) variability mechanisms and impact on the monsoon. Both configurations capture the main SEAS oceanographic features, and confirm that the winter SSS decrease results from horizontal advection of Bay of Bengal freshwater by the cyclonic circulation around India during fall. A coupled model sensitivity experiment where salinity has no effect on mixing indicates that the salinity stratification reduces the SEAS mixed layer cooling by vertical processes by 3 °C seasonally. Salinity however enhances mixed layer cooling by a similar amount through concentrating negative winter surface heat fluxes into a thinner mixed layer, resulting in no climatological impact on SST and summer monsoon rainfall. The Indian Ocean Dipole (IOD) is the main driver of the winter SEAS SSS interannual variability (r ~ 0.8). Salty anomalies generated in the western Bay of Bengal during fall by positive IOD events are indeed transported by the cyclonic climatological coastal circulation, reaching the SEAS in winter. By this time, warm IOD-induced SST anomalies in the SEAS are already decaying, and the SEAS SSS anomalies hence do not contribute to their development. Overall, our model results suggest a weak climatological and interannual impact of the SEAS winter freshening on local SST and following monsoon onset. [ABSTRACT FROM AUTHOR]

In this study, groundwater irrigation potential zones are identified by measuring an integrated irrigation water quality index using a GIS platform in the Vishwamitri River Basin (VRB) region, Gujarat, India. Classification of different irrigation potential zones is about the collective paraphernalia of thematic maps, namely, electrical conductivity (EC), sodium adsorption ratio (SAR), Na+, Cl−, and HCO3−, which principally regulate the groundwater quality for irrigation. The EC, SAR, and chloride values are > 3000 µS/cm, > 9 meq/L, and > 10 meq/L, respectively, indicating 98.78%, 41.78%, and 84.88% of the total area, respectively, belong to groundwater both hazardous and unsuitable for irrigation. Similarly, 39.55% of the total area is unsuitable for irrigation due to its high Na+ concentration. The permeability, porosity, and infiltration risk usually appear when excessive sodium ions reduce the rate of flow of irrigation water which moves in the lower soil zones. Similarly, high bicarbonate and chloride concentrations have been denoted to hamper the development of several crops causing symptoms analogous to lime-induced chlorosis due to toxic effects of the salt. The final irrigation potential map is marked by four levels, such as "most suitable," "moderately suitable," "moderately unsuitable," and "unsuitable for irrigation." Approximately, 56.69% of the total VRB region are covered with unsuitable for irrigation purposes. In such areas, irrigation must be avoided in usual conditions, and the halophytes, namely, Khati palak (Atriplex stocksii), Lamb's quarters (Chenopodium album), and Rudravanti (Cressa cretica) should be recommended with high soil permeability and proper drainage facilities. The soil must be highly permeable for groundwaters with high salinity and sodicity. Based on this study, policymakers and environmental managers can estimate the resource implications for drinking and irrigation. [ABSTRACT FROM AUTHOR]

Hooghly River, a ~460 km long distributary of the Ganga River, passes through a highly industrialized Metropolis-Kolkata in West Bengal, India, and eventually empties into the Bay of Bengal at Gangasagar. To determine the patterns and drivers of planktonic community, spatiotemporal variations in water quality and micronutrient content and planktic prokaryotic and microeukaryotic abundance and diversity across the salinity gradient (0.1 to 24.6 PSU) in the Hooghly River estuary (HRE) were studied. Plankton and water samples were collected at six sites during October 2017, February 2018, and June 2018. The biotic parameters—phytoplankton (Chlorophyll a), total bacterial abundance (cfu), and copepods—were significantly higher in the downstream estuarine sites than in the upstream riparian sites; conversely, rotifer and cladoceran abundances were significantly higher at upstream stations. The most culturable bacterial strains were isolated from the two freshwater sites and one at the confluence (estuarine) and are characterized as Bacillus subtilis, Pseudomonas songnenesis, and Exiguobacterium aurantiacum. Among zooplankton, rotifers (0.09 ± 0.14 ind L−1) and cladocerans (5.4 ± 8.87 ind L−1) were recorded in higher abundance and negatively correlated with bacterial concentrations at upstream stations. On the temporal scale, February samples recorded lower proportions of bacterivorous zooplankton at the three upstream stations. Cluster analysis separated samples on the basis of seasons and water mass movement. The February samples showed distinct spatial characteristics, as three freshwater (FW) stations grouped together and segregated at second 2nd hierarchical level, whereas the three estuarine stations formed a separate cluster at the 50% similarity level. Samples collected in October 2017 and June 2018 exhibited mixed attributes. June samples recorded higher influence of freshwater discharge. The zooplankton abundance showed significant negative correlation with Chl a. Our results demonstrate the relative role of river continuum, land-driven lateral discharge, and seawater intrusion in shaping community structure, which needs to be considered in management and conservation planning of aquatic ecosystems, especially in highly productive and overexploited HRE. [ABSTRACT FROM AUTHOR]

Observations in the Mandovi estuary, located on the central west coast of India, have shown that the salinity field in this estuary is remarkably time-dependent and passes through all possible states of stratification (riverine, highly-stratified, partially-mixed and well-mixed) during a year as the runoff into the estuary varies from high values (∼1000 m 3 s −1 ) in the wet season to negligible values (∼1 m 3 s −1 ) at end of the dry season. The time-dependence is forced by the Indian Summer Monsoon (ISM) and hence the estuary is referred to as a monsoonal estuary. In this paper, we use a three-dimensional, open source, hydrodynamic, numerical model to reproduce the observed annual salinity field in the Mandovi. We then analyse the model results to define characteristics of residual estuarine circulation in the Mandovi. Our motivation to study this aspect of the Mandovi's dynamics is derived from the following three considerations. First, residual circulation is important to long-term evolution of an estuary; second, we need to understand how this circulation responds to strongly time-dependent runoff forcing experienced by a monsoonal estuary; and third, Mandovi is among the best studied estuaries that come under the influence of ISM, and has observations that can be used to validate the model. Our analysis shows that the residual estuarine circulation in the Mandovi shows four distinct phases during a year: a river like flow that is oriented downstream throughout the estuary; a salt-wedge type circulation, with flow into the estuary near the bottom and out of the estuary near the surface restricted close to the mouth of the estuary; circulation associated with a partially-mixed estuary; and, the circulation associated with a well-mixed estuary. Dimensional analysis of the field of residual circulation helped us to establish the link between strength of residual circulation at a location and magnitude of river runoff and rate of mixing at the location. We then derive an analytical expression that approximates exchange velocity (bottom velocity minus near freshwater velocity at a location) as a function of freshwater velocity and rate of mixing. [ABSTRACT FROM AUTHOR]

The present paper examines the nature of salt movement by the influence of landscape position and development of secondary salinity in Indira Gandhi Nahar Pariyojana command area of hot arid India. Soil samples were collected along 20 km transect across landscapes of upland, medium land, lowland and wetland. Soil properties, electrical conductivity of saturated extract (ECe), soluble ions in saturated extracts, exchangeable sodium percentage (ESP) and sodium adsorption ratio were determined. Results showed that cation exchange capacity, organic carbon and CaCO3 were significantly increased in lowland and wetland while soil pH, salinity indicators (ECe and ESP) and exchangeable cations and anions such as chloride and sulphate were increased significantly (P < 0.05) in the wetland. The mean exchangeable Na was increased while exchangeable Ca, Mg, and K decreased from upland to wetland landscape. It was found that Cl− imposed an existing and potential threat to sensitive crops in medium to wetland, where Cl− concentrations were greater than 106 me L−1. Principal component analysis helped in the identification of the parameters responsible for soil salinity variation, and the first factor indicated that soil ECe and ESP had a major role in the development of salinity and sodicity, respectively. Cluster analysis grouped four sampling sites into three clusters and members of the third cluster (lowland and wetland) were in close proximity. Under the prevalent arid conditions, improving the management of irrigation water should be the indispensable one to conserve and sustain the already fragile agricultural soils in the hot arid regions of India. [ABSTRACT FROM AUTHOR]

Soil salinity is one of the major abiotic stresses that strongly affect seed germination in agriculture. In order to fulfill the need of demand in agriculture, seed priming is one of the promising techniques that enhance seed germination and uniformity. Isabgol, one of India's important medicinal crops, has a low germination rate. In Gujarat state, Isabgol has considered a cash crop, serving as a source of income to the farmers. Gujarat state faces many challenges, and seawater ingress is one of the major issues creating salinity in the soil, affecting seed germination. This research was carried out to study the effects of seed priming on seed germination behavior of Gujarat Isabgol variety 4. The method where KNO3 was used for priming with two different salinity levels, 0 dS/m, and 5.3 dS/m. The experiment was a completely randomized design. In this experiment, germination traits like germination percentage, Mean Germination Time, plumule length, radicle length, seed vigour, and fresh weight were measured. Data were analyzed by using SPSS software. The present study shows that halopriming with KNO3 at a lower concentration was quite an effective treatment since it significantly increased some of the germination traits of Gujarat Isabgol variety 4. [ABSTRACT FROM AUTHOR]

The present study highlights that seasonal salinity variability plays a significant role in meiobenthic distribution with special reference to nematode assemblages. Sediment and water samples were collected from Pulicat Lake, a hypersaline lake along the southeast coast of India during two seasons (Southwest Monsoon (SWM) and Northeast Monsoon (NEM)). Based on the salinity distribution, the lake is categorized into four regions, viz., southern inlet, central region, middle inlet, and northern inlet. Meiobenthic abundance was higher during SWM (226–12,206 Ind/10 cm2) than in NEM (640–10,424 Ind/10 cm2). The meiofaunal abundance was high in the central region during both the seasons, followed by the southern, northern, and middle inlet. The nematode was the dominant meiobenthic group, followed by copepod, polychaete, and foraminifera. Due to high organic matter, the central region was dominated by deposit feeding nematode species like Halalaimus longicaudatus and Terschellingia longicaudata. The southern and northern regions were dominated by free-living nematodes Rhabditis olitoria, Mesorhabditis capitata, Mononochus bastian, Paramononchus sp., Piranchulus sp., and Diploscapter cylindricus. Oncholaimus sp., a hypersaline indicator species, was reported from the middle inlet location. Statistical analysis suggests salinity as a critical parameter for the distribution and diversity of nematodes. [ABSTRACT FROM AUTHOR]

The atmospheric methane (CH4) concentration has increased in recent years due to natural and anthropogenic causes. Hence, it is essential to quantify the potential sources of CH4 to understand the factors responsible for its fluxes on a local to regional scale through in situ observations. Coastal wetlands, particularly the mangrove ecosystems in the tropical and subtropical coasts, are significant sources of CH4. In this study, we used an eddy covariance-based technique to measure the CH4 fluxes in a mangrove ecosystem in Pichavaram, South India. The daily mean CH4 flux ranged from 12 to 26 nmol m−2 s−1 during the wet season and from 6 to 20 nmol m–2 s–1 during the dry season. The monthly mean flux during the wet period was between 0.8 and 1.8 g CH4 m−2 month−1, and in the dry season, it was between 0.4 and 0.6 g CH4 m−2 month−1. The visual correlogram and structural equation modelling technique revealed that air temperature, creek water dissolved oxygen, soil organic carbon, and redox potential are important factors that control the CH4 fluxes. The results suggest that the Pichavaram mangrove wetland acts as a source for CH4. Our results also indicate that tidal inundation and seasonal variations in atmospheric temperature and water salinity are key factors affecting the CH4 flux in the Pichavaram mangrove ecosystem. [ABSTRACT FROM AUTHOR]

Increasing salinity is one of the most significant and widespread forms of groundwater pollution in coastal areas. This paper presents the causes and impacts of saline water intrusion in coastal areas. Various causes of salt water intrusion, and approaches for the determination of its extent and various measures to control the salt water intrusion are described. An aquifer performance test (APT) approach is presented to identify the extent of existing salt water intrusion in the study area located in the southwest coastal region of Gujarat State (India). A resistivity based experimental technique is used to identify the quality of the groundwater available at different depths. A methodology is presented to assess the extent of available fresh and saline groundwater and to find out the limit up to which lower saline groundwater can be withdrawn for industrial purposes without affecting the upper fresh water layer which can be made available for domestic purposes. [ABSTRACT FROM AUTHOR]

Commercial aquaculture in India has come under attack for having caused negative agricultural and environmental impacts. This paper formulates an interactive model of non-renewable and renewable resources to characterize land allocations between aquaculture and agriculture in ecologically and economically sustainable fashion. Through an empirical application, various economic and policy circumstances that affect the optimal land allocation mix are evaluated. The aquaculture industry must address two economic effects: off-site negative effects on renewable food and other coastal resources, and on-site self-pollution of shrimp ponds. Current regulatory and land-use policies are inadequate to address these effects. [ABSTRACT FROM AUTHOR]

The halotolerant phosphate-solubilizing fungus Penicillium sp. NAUSF2 was isolated from rhizospheric soil in coastal regions of South Gujarat, India, and identified on the basis of morphological characteristics and internal transcribed spacer gene sequence (ITS1 and ITS4). The isolate solubilized rock phosphate up to 843 µM. There was drop in pH with the secretion of gluconate (31.7 mM) and oxalate (3.2 mM) mediated by the high glucose oxidase and oxaloacetate acetylhydrolase activities, respectively. This fungus also demonstrated plant growth-promoting activities such as indole-3-acetic acid (127.82 g/L) and siderophore production. Inoculation of Penicillium sp. NAUSF2 to Vigna radiata (mung bean) significantly increased plant P uptake and growth parameters. It showed reduced disease severity index due to increased levels of antioxidative enzymes and jasmonic acid when treated with the leaf spot pathogen Xanthomonas axonopodis pv. V. radiata. These results suggest the potential of Penicillium sp. NAUSF2 as a biotechnological tool to help plants to cope up with stress in saline soils and broaden the spectrum of phosphate solubilizers available for field application. [ABSTRACT FROM AUTHOR]

This study correlated the abundance of five jellyfish species in the south-west coast of India, South-eastern Arabian Sea, Crambionella orsini, Lychnorhiza malayensis, Chrysaora caliparea, Netrostoma coerulescens and Cyanea nozakii, with hydrographic parameters. Partial least square (PLS) analysis suggested strong correlations between jellyfish abundance and phosphate, silicate and chlorophyll-a content in water and showed a significant positive relationship with the first PLS component, while pH and sea surface temperature showed a significant negative correlation with the first PLS component, indicating that the abundance of four species, C. caliparea, C. nozakii, L. malayensis and N. coerulescens, increases with phosphate, silicate and chlorophyll-a content and decreases with pH and sea surface temperature. In contrast, the abundance of C. orsini increased with an increase in sea surface salinity and decreased with an increase in dissolved oxygen; except for this species, the abundance of jellyfish in the South-eastern Arabian Sea was positively affected by phosphate content of the water. The continuous decline in abundance of jellyfish from 2016 to 2019 in the south-west coast of India could be due to the influence of regional environmental changes or due to the specific ecological strategies of the jellyfish species in the upwelling zone subjected to high fishing pressure. [ABSTRACT FROM AUTHOR]

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Inland athalassohaline solar salterns provide unique opportunity to study microbial successions along salinity gradients that resemble transition in natural hypersaline lakes. We analyzed for the first time 16S rRNA gene amplicon sequences of bacteria (V1–V2) and archaea (V4–V5) in saltern brines of India's largest inland hypersaline Sambhar Lake. Brines of the salterns (S1–S4) are alkaline (pH 9.5–10.5) with salinities of 130, 170, 280 and 350 gL−1 respectively. 16S rRNA gene copy-number of archaea outnumbered that of bacteria in all salterns. Their diversity also increased along S1 through S4, while that of bacteria decreased. Brines of S3 and S4 were dominated by specialized extreme halophilic bacterial (Halanaerobiales, Rhodothermaceae) and archaeal (Halobacteriales, Haloferacales) members with recognized salt-in strategy for osmoadaptation. Microbial assemblages positively correlated to saltern pH, total salinity, and ionic composition. Archaea in S1 and S2 were unprecedentedly represented by poorly known as-yet uncultivated groups, Woesearchaeota (90.35–93.51%) and Nanohaloarchaeota that belong to the newly proposed nano-sized superphylum DPANN. In fact, these taxa were identified in archaeal datasets of other athalassohaline salterns after re-analysis using latest RDP database. Thus, microbial compositions in hypersaline lakes are complex and need revisit particularly for their archaeal diversity to understand their hitherto unknown ecological function in extreme environments. [ABSTRACT FROM AUTHOR]

Major parts of agricultural lands in arid and semi-arid regions of India are affected by soil salinity and waterlogging in canal command area and outside. Waterlogging is caused by a rising water table and poor drainage conditions. Stress due to waterlogging and salinity are serious to plants in all stages from seed germination to active growth and maturity. Unmanaged affected agricultural lands turn into low productive marshlands in the long run. Physical provision of surface or sub-surface drainage structures can rescue in such a situation. Yet, high skill and investment are required in the installation and maintenance of such structures. Alternatively, biodrainage method has been evolved as an effective method recently world over. In biodrainage, plants are raised over a larger area, which can transpire and remove an enormous amount of water from the soil. Plants having adequate adaptive traits and tolerance mechanisms are desirable to mitigate waterlogging and salinity. Biodrainage is suitable in rainfed and irrigated conditions. Planting of right plant species in optimum population and geometry decides the efficiency of biodrainage. Further, combining biodrainage with the conventional drainage can improve land and water productivity. Eucalyptus is the most suitable tree species for biodrainage as it has well performed in versatile environments. It possesses appreciable tolerance to salinity, sodicity and waterlogged conditions of the soil. Fast-growing with a straight trunk, deep rooting ability, low shading effect and high transpiration capacity are promising characteristics of this tree. Prominent woody species like Acacia nilotica, Dalbergia sissoo, Hardwickia binata can also be grown for high profit. [ABSTRACT FROM AUTHOR]

Salinity stress is the most prominent stress impacting rice productivity worldwide. In the past, several quantitative trait loci (QTLs) for salinity tolerance had been identified in rice, however their utilization in rice breeding programs is largely confounded due to the unwanted linkage drag associated with the QTL region. Thus, it is strongly desirable to delimit the QTL region to a least possible chromosomal interval minimising any unwanted association. Addressing this, we have evaluated 68 recombinant inbred lines (RILs) derived from a cross between a salinity tolerant parent 'Kolajoha' and a salinity sensitive parent 'Ranjit' for identification of QTL(s) involved in imparting salinity tolerance at seedling stage. Genotyping by sequencing approach (GBS) was followed for SNP identification at genome wide scale. Around 3649 SNPs were identified by GBS method initially at 20% minor allele frequency. After filtering of SNPs with polymorphism with less than 10–15% of missing data, a total of 1248 SNPs were mapped to 1247 recombination points and the genetic map was constructed with a total map length of 1201.21 cM and resolution of 0.95 cM between markers. For 10 traits, a total of 23 additive QTLs were identified of which only 1 was a major QTL and 22 were minor QTLs. The average QTL interval size is about 2945 kb. Epistatic QTL mapping had identified one pair of QTLs that contribute significantly in the phenotypic variation of traits among the RILs. Total 1895 genes were identified in the QTL intervals, majority of them are located in Chr1 of rice genome between 22.09 and 38.29 Mb region. Although, this region is not very narrow, some of the genes falling in this region can be utilized for validation of QTLs in future. One differentially methylated region was found to be colocalized within the QTL intervals determined in Chr2 which indicates their potential role in epigenetic modifications in improving stress tolerance in rice. [ABSTRACT FROM AUTHOR]

A preliminary hydrogeochemical investigation of groundwater quality for spatially distributed habitations of Chandel district of Manipur was carried out with an objective to assess the suitability of groundwater for different anthropogenic uses. Altogether, eighteen (18) physico-chemical parameters including in situ parameters and major ions were analysed for classification and hydrogeochemical characterisation of groundwater resources of the study area. Some of the anions such as Cl− and SO42− were found in exceeding concentrations. Similarly, 23.1% samples exceed fluoride (F−) concentration beyond the permissible limit of 1.5 mg/l. The water quality index of the groundwater samples of the habitations was found to be influenced by the elevated concentrations of water quality parameters such as F−, EC, TDS, salinity, Cl− and SO42−. The geochemical analysis reveals that the majority of geochemical facies of the groundwater samples are dominated by Na+–Ca2+–Mg2+–Cl−–HCO3−–SO42− type of water resulting from rock-weathering geochemical process. Bivariate and multivariate analysis indicates the influences of hydrogeochemical interactions in the aquifer on the overall water quality. The irrigational water quality indices demonstrate that the water qualities of most of the sources are within the acceptable range except for few samples with high salinity and alkali hazards. [ABSTRACT FROM AUTHOR]

Shoots of ten day old seedlings of nineteen wheat genotypes were evaluated for proline metabolism, H2O2, thiobarbituric acid reactive substances (TBARS) and 2,2 diphenyl-picrylhydrazyl (DPPH) radical scavenging activity under water deficit, water withholding and salinity stress conditions. Principle component analysis demarcated four groups: i.e. drought tolerant (Excalibar, Krichauff, Babax, Drysdale, Gladius and C306), salt tolerant (Kharchia, Type11, Krl 1-4 and Krl 19), low stress tolerant (C273, C518 and C591) and susceptible (HD2967, PBW621, WH1105, HD3086, PBW660 and PBW175). Salt stress treatment affected the length, fresh weight and dry weight of seedlings of all studied genotypes in comparison to water deficit and water withholding condition which may be due to higher contents of TBARS. Shoots of salt and drought tolerant genotypes possessed higher proline content and DPPH radical scavenging activity alongwith reduced content of TBARS in parallel with decreased H2O2 content under water stress conditions. The activities of proline synthesizing enzymes i.e. pyrroline-5-carboxylate synthetase (P5CS) and pyrroline-5-carboxylate reductase (P5CR) were significantly higher than proline degrading enzyme viz. proline dehydrogenase (PDH) under water stress as compared to salinity stress conditions. Overall, results indicated that P5CS, P5CR and PDH activities led to higher build up of proline under water stress, which might play a significant role in improving membrane stability by increasing radical scavenging activity and finally imparting stress tolerance in specific wheat genotypes. [ABSTRACT FROM AUTHOR]

Trichodrema is considered to be the most beneficial fungal genus for protecting crops in organic systems. The present study focuses on isolation, screening and identification of salinity tolerant Trichoderma isolates from eastern Uttar Pradesh, India. Among all the Trichoderma isolates, BHUT6 and BHUT8 were highly salt tolerant under in vitro condition and showed good growth up to 1400 mM NaCl concentration. The highest salinity tolerant Trichoderma BHUT8 isolate was selected for further study. This isolate was identified as Trichoderma asperellum (accession number KU533735). T. asperellum BHUT8 also possessed temperature tolerance showing good growth up to 38 °C. The BHUT8 isolate also showed biocontrol potential against major soilborne phytopathogens namely Scletotium rolfsii, Fusarium oxysporum, Colletotrichum capsici, Rhizoctonia bataticola, and Sclerotinia sclerotiorum in dual culture assay. Amylolytic, proteolytic and chitinolytic activities of BHUT8 were also high, and produced IAA, HCN, siderophore and solubilised phosphate. [ABSTRACT FROM AUTHOR]

Salinity is a major abiotic factor that affects rice cultivation in the world along the coastal areas. The salt affected areas in India is estimated to be around 8 to 10 million hectares that causes significant reduction in rice growth and yield. In order to improve the rice cultivars for salt tolerance, selection of the suitable genotypes is necessitated. Hence, in this experiment ninety seven rice genotypes including traditional landraces were collected and subjected to screening under salt stress by hydroponics system on Yoshida nutrient solution of EC 8 dSm-1and 12 dSm-1 with 4 replications. The genotypes were scored on 15th day after sowing based on standard evaluation scoring system of IRRI. Among the 97 rice genotypes scored, 5% were tolerant, 21% were moderately tolerant, 54% genotypes were susceptible and 18% were highly susceptible. The rice genotypes viz., Pokkali, FL478, Kuliyadichan, Gurukot and IR12L-107 revealed significant level of tolerance to salt stress. The rice genotypes, Pokkali and FL478 showed no symptoms at 8 dSm-1 and leaf rolling alone at 12dSm-1. Kuliyadichan, Gurukot and IR12L-107 showed leaf rolling at 8dSm-1 and leaf rolling and leaf tip burning at 12dSm-1. Screening of the rice genotypes for salinity tolerance only by visual symptoms is not reliable and hence the selected rice genotypes will further be characterized based on the morphological and biochemical parameters under salt stress in order to select elite salt tolerant rice genotypes for use in developing salinity tolerant somaclones by in vitro culture. [ABSTRACT FROM AUTHOR]

Our understanding on the importance of viral lysis in the functioning of tropical estuarine ecosystem is limited. This study examines viral infection of prokaryotes and subsequent lysis of cells belonging to different morphotypes across a salinity gradient in monsoon driven estuarine ecosystem (Cochin estuary, India). High standing stock of viruses and prokaryotes accompanied by lytic infection rates in the euryhaline/mesohaline region of the estuary suggests salinity to have an influential role in driving interactions between prokaryotes and viruses. High prokaryotic mortality rates, up to 42% of prokaryote population in the pre-monsoon season is further substantiated by a high virus to prokaryote ratio (VPR), suggesting that maintenance of a high number of viruses is dependent on the most active fraction of bacterioplankton. Although myoviruses were the dominant viral morphotype (mean = 43%) throughout the study period, there was significant variation among prokaryotic morphotypes susceptible to viral infection. Among them, the viral infected short rod prokaryote morphotype with lower burst estimates (mean = 18 viruses prokaryote-1) was dominant (35%) in the dry seasons whereas a substantial increase in cocci forms (30%) infected by viruses with high burst size (mean = 31 viruses prokaryote-1) was evident during the monsoon season. Such preferential infections of prokaryotic morphopopulations with respect to seasons can have a strong and variable impact on the carbon and energy flow in this tropical ecosystem. [ABSTRACT FROM AUTHOR]

Lateral submesoscale processes and their influence on vertical stratification at shallow salinity fronts in the central Bay of Bengal during the winter monsoon are explored using high-resolution data from a cruise in November 2013. The observations are from a radiator survey centered at a salinity-controlled density front, embedded in a zone of moderate mesoscale strain (0.15 times the Coriolis parameter) and forced by winds with a downfront orientation. Below a thin mixed layer, often ≤10 m, the analysis shows several dynamical signatures indicative of submesoscale processes: (i) negative Ertel potential vorticity (PV); (ii) low-PV anomalies with O(1-10) km lateral extent, where the vorticity estimated on isopycnals and the isopycnal thickness are tightly coupled, varying in lockstep to yield low PV; (iii) flow conditions susceptible to forced symmetric instability (FSI) or bearing the imprint of earlier FSI events; (iv) negative lateral gradients in the absolute momentum field (inertial instability); and (v) strong contribution from differential sheared advection at O(1) km scales to the growth rate of the depth-averaged stratification. The findings here show one-dimensional vertical processes alone cannot explain the vertical stratification and its lateral variability over O(1-10) km scales at the radiator survey. [ABSTRACT FROM AUTHOR]

Assessment of change in major ion chemistry of groundwater, manifested by hydrochemical facies, is a necessity for sustainable use of the groundwater resources. In this perspective, this article estimates spatial and temporal hydrochemical facies variation in the study area using an integrated approach. The geochemical, isotopic and sedimentary data from the North West Delhi has been used to achieve the objective of the study. It is seen that the spatial groundwater facies variation in the study area correlates with the change in geomorphologic units. Distinct hydrochemical facies for younger and older alluvial plains has been observed. It is seen that geomorphic features such as palaeochannels also influence the groundwater quality of the study area. Further, the temporal hydrochemical facies variations indicate that with time, anthropogenic factors have also impacted the evolution of facies in the study area . [ABSTRACT FROM AUTHOR]

Water quality analysis is prime important to understand the wealth of living organism and environmental condition in water bodies. In GIS, ordinary Kriging interpolation method has been applied for surface analysis of water quality parameters such as temperature, salinity, pH, chlorophyll-a (Chl-a) and suspend sediment (SS), to carried comparison analysis between monsoon and summer season in lagoon at Vedaranyam wetland. Kriging is an approach to mapping the water quality parameters for analyzing the dispersion patterns. The results of the spatial distribution analysis has been indicated in lagoon around salt pan and aquaculture area have high saline condition reach about 36 parts per thousand (ppt) and in monsoon seasons suspended sediment reach maximum due to river runoff in the study area. [ABSTRACT FROM AUTHOR]

Tropical cyclones are extreme random meteorological events that can have profound implications to coastal biodiversities. Given that the frequency, intensity and duration of these events are poised to increase due to the global climate change, understanding the ecological impacts of such erratic occurrences becomes imperative to devise better management strategies. The eventful passage of the tropical cyclone, Phyan, along the northwestern coast of India in November 2009, coupled with the availability of historical data presented a rare opportunity to elucidate the consequences on the polychaete assemblages of the Malvan Marine Sanctuary and their subsequent recovery. This was achieved by comparison of the pre- and post-Phyan seasonal data from four different sites in and around the Sanctuary. MDS analyses and polychaete community parameters suggested conspicuous cyclone related effects on the polychaete community characteristics in the three outer stations off Malvan, whereas the relatively protected bay station remained more or less unscathed. Impacts, attributable to the cyclone apart from seasonal variations, included changes in polychaete composition, reductions in total polychaete density, species diversity, evenness and functional groups. Dominance of the opportunistic polychaete, Paraprionospiopatiens was all pervasive just after Phyan, resulting in poor diversity and evenness values. In the outer stations, diverse feeding modes present prior to the cyclone were replaced by microphagous feeders post the disturbance. However, the study also observed complete recovery as substantiated by the improvement inpolychaete density, diversity indices and re-instatement of multiple feeding guilds in affected areas. This resilience of the coastal waters off Malvan is attributed to its marine protected status, implying that reduced human interference aided rapid revival of damaged ecosystems. [ABSTRACT FROM AUTHOR]

The species composition in the mangrove habitats of India is reviewed and discussed. The review shows that Indian mangroves consist of 46 true mangrove species belonging to 14 families and 22 genera, which includes 42 species and 4 natural hybrids. In other words, about 57% of the world's mangrove species are represented in India. The East coast has 40 mangrove species belonging to 14 families and 22 genera. The West coast has 27 species belonging to 11 families and 16 genera and the Andaman and Nicobar Islands (ANI) have 38 species belonging to 13 families and 19 genera. Among the 13 States/Union Territories having mangroves, diversity is highest in the ANI. Species namely Rhizophora × lamarckii, Lumnitzera littorea, Sonneratia ovata, S. lanceolata, S. × urama and S. × gulngai are restricted to ANI in India. In terms of mangrove diversity, India is the third richest country in the world (after Indonesia and Australia). However, a majority of the Indian mangrove habitats are now threatened by various factors such as reduction in freshwater flow, marine & coastal pollution, siltation, sedimentation and excessive salinity. Periodical floristic surveys are needed to monitor and preserve the rich mangrove plant diversity in India. [ABSTRACT FROM AUTHOR]

Seismic oceanographic studies from various oceans worldwide have indicated that the acoustic reflections are mostly observed along thermal boundaries within the water column. However, the authors present a case study of seismic data from Krishna-Godavari Basin which shows that salinity variations also play an important role in the occurrence of water column reflections. The observed reflection is modeled using the reflectivity series derived from the salinity and temperature profiles from a nearby Conductivity-Temperature-Depth (CTD) location. Sensitivity analysis of temperature and salinity on soundspeed shows that the effect of salinity cannot be ignored for modeling acoustic reflections. The synthetic seismogram matches well with the observed reflection seismic data. Remarkable similarities between the reflection seismic and the salinity profile in the upper thermocline suggest the importance of salinity variations on the water column reflection. Furthermore, impedance inversion of the reflectivity data reveals several thermohaline structures in the water column. The origin of these thermohaline structures is largely unaddressed and may be attributed to the fresh water influx coming from Himalayan and Peninsular rivers or due to the presence of different water masses in the Indian Ocean which warrants a detailed study using concurrent seismic and CTD data. [ABSTRACT FROM AUTHOR]

Inceptisols and Vertisols are two dominant soil orders that support major agricultural production in India. These soils often exist in semi-arid and arid regions. Low precipitation and high evaporation demand leads to salt accumulation in these areas. The problem of salt accumulation is further compounded by the presence of saline/alkaline groundwaters. We evaluated the effect of modified Ca/Mg waters on ionic composition, dispersion, and clay flocculation of sodic Inceptisols, saline-sodic Inceptisols, and normal Vertisols from different parts of India. A completely randomized factorial design with three replications of individual soils were sequentially leached with five pore volumes of deionized, saline water of 60 and 120 me L−1total electrolyte concentration (TEC) at a fixed SAR of 5.0 mmol1/2 L−1/2and Ca:Mg ratio of 2:1, 1:1 and 1:2. Application of saline waters decreased pH and increased EC of the soil leachates after leaching five pore volumes of three Ca/Mg ratios of 60 and 120 me L−1solutions in sodic Inceptisols and normal Vertisols. In saline-sodic Inceptisols, application of saline waters decreased both pH and electrical conductivity (EC) of the soil leachates. Preferential Ca2+holding in soil was only noticed in sodic Inceptisols when leaching process was performed with independent saline waters, but Mg2+has a tendency to hold in soil upon application of independent saline waters for all soils except sodic Inceptisols. Periodic application of deionized water could increase soil dispersion and decreased flocculation of clay particles. Mg2+ion had less flocculating vis-à-vis high-dispersion effect on soil clays than the Ca2+ion. [ABSTRACT FROM AUTHOR]

Flooded rice is grown across wide geographic boundaries from as far north as Manchuria and as far south as Uruguay and New South Wales, primarily because of its adaptability across diverse agronomic and climatic conditions. Salt-stress damage, a common occurrence in delta and coastal rice production zones, could be heightened by the interactions between high temperature and relative humidity (vapor pressure deficit - VPD). Using temporal and spatial observations spanning 107 seasons and 19 rice-growing locations throughout India with varying electrical conductivity ( EC), including coastal saline, inland saline, and alkaline soils, we quantified the proportion of VPD inducing salinity damage in rice. While controlling for time-invariant factors such as trial locations, rice cultivars, and soil types, our regression analysis indicates that EC has a nonlinear detrimental effect on paddy rice yield. Our estimates suggest these yield reductions become larger at higher VPD. A one standard deviation ( SD) increase in EC from its mean value is associated with 1.68% and 4.13% yield reductions at median and maximum observed VPD levels, respectively. Yield reductions increase roughly sixfold when the one SD increase is taken from the 75th percentile of EC. In combination, high EC and VPD generate near catastrophic crop loss as predicted yield approaches zero. If higher VPD levels driven by global warming materialize in conjunction with rising sea levels or salinity incursion in groundwater, this interaction becomes an important and necessary predictor of expected yield losses and global food security. [ABSTRACT FROM AUTHOR]

The Asia's largest lagoon, Chilika, is a shallow water estuary and a designated 'Ramsar' site located in the east coast of India. The spatiotemporal diversity of phytoplankton based on the monthly sampling between July 2011 and June 2012 was investigated in relation to physicochemical variables of the surface water column from 13 stations. The salinity was minimum (average 9) during the monsoon which was primarily due to riverine discharge. As the season progressed towards post-monsoon, average salinity of the whole lagoon reached to 10 which further increased to 20 during pre-monsoon season. A total of 259 species of phytoplankton, mostly dominated by the Bacillariophyta (138 species) followed by Dinophyta (38 species), Chlorophyta (32 species), Cyanophyta (29 species), Euglenophyta (18 species), and Chrysophyta (4 species), were recorded in this study. Different ecological sectors of the lagoon (except the northern sector) were dominated by diatoms, while the northern sector due to its freshwater regime supported large population of euglenoids. Based on the multivariate ordination analysis, salinity regime and light availability played important role in determining the distribution, diversity, and composition of phytoplankton communities. Overall, this study documented a very high diversity of phytoplankton and highlighted the importance of taking extensive sampling in getting a clearer understanding of phytoplankton community structure in less-studied environments such as Chilika lagoon. [ABSTRACT FROM AUTHOR]

The intensive use of chemical fertilizers, monoculture and irrigation with surface saline water has resulted in the deterioration of soil health by enhancing the level of salinity in the Eastern Indo-Gangetic Plains of India. Therefore, diversity of halotolerant bacteria adapted to that environment and possessed the ability to produce plant growth hormones was explored, that could be used for salt stress amelioration. The 16S rRNA gene sequencing and fatty acid methyl ester (FAME) were used for diversity analysis of salt-tolerant bacilli. Among the 95 isolates, 55 strains showed plant growth promotion traits, production of industrially important enzymes (amylase, protease and cellulase) and tolerance to more than 4% NaCl. Using partial 16S rRNA sequences and FAME comparisons, 21 different species ofBacillusandBacillus-derived genera were identified, viz.Bacillus megaterium, B. subtilis, B. licheniformis, B. firmus, B. horikoshii, B. pumilus, Bacillussp.,B. safensis, B. thuringiensis, B. simplex, B. agri, B. flexus, B. oceanisediminis, B. cereus, B. arsenicus, Paenibacillus dendritiformis, Lysinibacillussp.,L. sphaericus, B. marisflavi, Terribacillussp., andB. mycoides.These isolates possess the ability to tolerate high salt, form endospores, withstand harsh environments, and also have the potential for plant growth promotion, which could be useful in formulation of new inoculants to enhance the availability of nutrients for crop growth under saline conditions. [ABSTRACT FROM AUTHOR]

Being the only tropical ocean bounded by a continent to the north, the Indian Ocean is home to the most powerful monsoon system on Earth. Monsoonal rains and winds induce huge river discharges and strong coastal currents in the northern Bay of Bengal. To date, the paucity of salinity data has prevented a thorough description of the spreading of this freshwater into the bay. The potential impact of the salinity on cyclones and regional climate in the Bay of Bengal is, however, a strong incentive for a better description of the water cycle in this region. Since May 2005, the National Institute of Oceanography conducts a program in which fishermen collect seawater samples in knee-deep water at eight stations along the Indian coastline every 5 days. Comparison with open-ocean samples shows that this cost-effective sampling strategy is representative of offshore salinity evolution. This new dataset reveals a salinity drop exceeding 10 g kg−1 in the northern part of the bay at the end of the summer monsoon. This freshening signal propagates southward in a narrow (~100 km wide) strip along the eastern coast of India, and reaches its southern tip after 2.5 months. Satellite-derived alongshore-current data shows that the southward propagation of this 'river in the sea' is consistent with transport by seasonal coastal currents, while other processes are responsible for the ensuing erosion of this coastal freshening. This simple procedure of coastal seawater samples collection could further be used to monitor phytoplankton concentration, bacterial content, and isotopic composition of seawater along the Indian coastline. [ABSTRACT FROM AUTHOR]

The most used temperature and salinity climatology for the world ocean, including the Indian Ocean, is the World Ocean Atlas (WOA) (Antonov et al 2006, 2010; Locarnini et al 2006, 2010) because of the vast amount of data used in its preparation. The WOA climatology does not, however, include all the available hydrographic data from the Indian Exclusive Economic Zone (EEZ), leading to the potential for improvement if the data from this region are included to prepare a new climatology. We use all the data that went into the preparation of the WOA ( Antonov et al 2010; Locarnini et al 2010), but add considerable data from Indian sources, to prepare new annual, seasonal, and monthly climatologies of temperature and salinity for the Indian Ocean. The addition of data improves the climatology considerably in the Indian EEZ, the differences between the new North Indian Ocean Atlas (NIOA) and WOA being most significant in the Bay of Bengal, where the patchiness seen in WOA, an artifact of the sparsity of data, was eliminated in NIOA. The significance of the new climatology is that it presents a more stable climatological value for the temperature and salinity fields in the Indian EEZ. [ABSTRACT FROM AUTHOR]

During winter, along the east coast of India, the near-surface flow is characterized by the southward-flowing East India Coastal Current (EICC) which bends around Sri Lanka and enters into the south-eastern Arabian Sea (AS). This current carries cooler, low-salinity waters from the head Bay of Bengal (BoB) into the south-eastern AS. But due to a lack of any direct in situ measurements, it is not clear whether any part of this current that flows through the Indo-Sri Lanka Channel (ISLC) is significant. An attempt is made in this study to look for any observational evidence for the southward flow of cooler, low salinity waters through the ISLC during winter. In the absence of direct in situ measurements on the observed currents in the non-navigable shallow ISLC, the observed high resolution, advanced very high resolution radiometer (AVHRR) sea surface temperature (SST), and sea-viewing wide field-of-view sensor (SeaWiFS) chlorophyll-a and historic sea surface salinity (SSS) data are utilized as tracers to track any southward water flow through the Pamban Pass and Adam's Bridge in the ISLC. The analysis suggests that both the non-navigable shallow Pamban Pass and the Adam's Bridge in the ISLC act as barriers and limit the southward flow of cooler, low salinity waters into the Gulf of Mannar in the south during winter. [ABSTRACT FROM AUTHOR]