Browsing by Author "Tripathy S."

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Geochemical characterization of coal and waste rocks from a high sulfur bearing coalfield, India: Implication for acid and metal generation
(2014) Sahoo P.K.; Tripathy S.; Panigrahi M.K.; Equeenuddin S.
An integrated study on coal and mine wastes from the Jaintia Hills coalfield of Meghalaya, India involving mineralogy, acid base accounting (ABA), and net acid generation (NAG) potential and sequential leaching was undertaken to examine their potential in controlling the acid mine drainage (AMD). Mineralogical study revealed that pyrite is the major sulfide mineral in coal and mine waste, being more abundant in sandstone and carbonaceous shale; while, dolomite and calcite are abundant in a few shale and siltstones, and Fe and Al copiapites are enriched in sulfate salts. During the ABA test, all coals and > 50% of mine waste showed paste pH < 4, implying their acid generating nature. Further, the relations between net neutralization potential (NNP) and acid producing ratio (APR) revealed that blocky pyrite, pyritiferrous sandstone and efflorescent salts contribute acid much higher than coal, siltstone and carbonaceous shale. This inference is consistent with the NAG test. Partitioning of metals in mine waste indicates high proportions of them in the blocky pyrite being bioavailable than from other rocks. While Mn is highly bioavailable, major portions of Pb and Zn are in the reducible and oxidizable fractions. In efflorescent sulfate salts, >. 80% of metals are available in water soluble fraction; thus these minerals can be considered as the highest polluting residue in the mining environment. These minerals easily precipitate from AMD solution in dry periods and can re-dissolve under rain events because of their high solubility; therefore, they can play an important role in controlling the chemistry of mine drainage in regard to local climate change. In the case of coal, only small fractions of Mn, Ni, Zn, Cd, and Pb are released to the environment, though high proportions of them can become bioavailable under oxidizing conditions besides their other bioavailable forms. � 2014 Elsevier B.V.
Green practices adopted by the mining supply chains in India: A case study
(2016) Muduli K.; Barve A.; Tripathy S.; Biswal J.N.
Growing public awareness regarding mining environmental issues has put mining industries under a lot of pressure lately from everyone including government and their investors. In response to these pressures, mining industries worldwide have taken various green initiatives [for example, green supply chain management (GSCM)] to minimise their wastes and emissions and enhance performance and economic front. However, a large number of Indian mining industries are blamed for poor GSCM performance. The reason being unavailability of sector specific implementation guidelines or/and inadequate information regarding the factors that influence GSCM adoption. Hence, cases of three mining sectors and the green practices adopted by them are investigated in this research and it was found that apart from challenges suffered by small scale industries the green attempts made by large scale industries have been successful. Few policy suggestions recommended by the study helps validate the barriers of GSCM implementation and improve performance of mining industries particularly the smaller ones upon adoption. Copyright � 2016 Inderscience Enterprises Ltd.
A Grey Relation Approach for Selection of Industrial Robot
(2018) Muduli K.; Pumwa J.; Yadav D.K.; Kumar R.; Tripathy S.
The necessity of robots in industries, especially, manufacturing, logistics, and similar applications has reached the zenith. Therefore, in a manufacturing environment, a crucial problem is to select a mechanized robot for carrying out certain industrial tasks. The latest development in automation has enhanced the use of robots with distinctive abilities, attributes, and requirements. The competitiveness of a company in relation to productivity and quality of products is unfavorably affected through inappropriate choice of robots. For decision makers, it is hard to decide the most suitable robot reflecting on the numerous contradictory qualitative and quantitative criteria. Hence, Grey relational analysis (GRA) is an effective estimation approach, which is internationally employed in multi criterion decision making (MCDM) problems, mainly owing to ambiguity in decisions that has been proposed in this research. A few robot selection parameters were considered, and GRA was employed to evaluate the best robot as per grey relational grade. � 2018 IEEE.
Impact of Rapid Urbanization on the City of Bhubaneswar, India
(2017) Swain D.; Roberts G.J.; Dash J.; Lekshmi K.; Vinoj V.; Tripathy S.
Rapid and unplanned urbanization of cities has been a cause of great concern world over. Increased urbanization has immensely altered the Land Use pattern of several Indian cities, thereby altering the physical properties of the land surface. The pronounced effect of urban heat island (UHI) apart from the acute stress on limited natural resources are consequences of this rapid urbanization. UHI effect manifests as unexpected rise in city temperatures when compared to their surrounding areas, thus making them unfriendly for habitation over time. The present work analyses the effect of UHI on Bhubaneswar, an Indian city undergoing rapid urbanization in recent times, utilizing land use and land cover (LULC) change data from Landsat over a 25�km radius about the city and MODIS land surface temperatures (LST) at 1�km2 spatial resolution for a period of 15�years (2000�2014). From the study, significant changes in LULC through over-exploitation of natural resources and the related spatio-temporal variations in LST has been identified as one major factor responsible for changes in the UHI effect over Bhubaneswar. Owing to rapid urbanization (83% increase in 15�years), the city has undergone major changes in LULC aggregating to a massive ~�89% decrease in dense vegetation and ~�83% decrease in crop fields over this time period. Analyses of the changes in the urban energy balance and resulting UHI effect across many such Indian cities undergoing rapid urban growth is quite essential for mitigating the negative impacts of urbanization for a long-term sustainability. � 2017, The National Academy of Sciences, India.
Impact of rapid urbanization on the microclimate of Indian cities: A case study for the city of Bhubaneswar
(2016) Swain D.; Roberts G.J.; Dash J.; Vinoj V.; Lekshmi K.; Tripathy S.
The impact of rapid urbanization in cities on their microclimate is at present a great cause of global concern. One of the major consequences is the unexpected rise in temperatures in the cities compared to their surrounding areas, termed as the Urban Heat Island (UHI) effect. Over the past many years, several Indian cities are under severe stress owing to such extreme anomalous changes in their micro-meteorological conditions making them unfriendly for habitation. Presented here is a case study on Bhubaneswar - one such city on the east coast of India undergoing rapid urbanization in recent times. In this study, Land Surface Temperatures (LST) from MODIS Terra and Aqua instruments at 1 km2 spatial resolution along with the Land Use and Land Cover (LULC) change data from Landsat was used over a 25 km radius about the city for a 15 years' period from 2000 to 2014. Preliminary analyses indicate spatio-temporal changes in LULC to be one of the primary and significant factors responsible for changes in the UHI effect over the city. Investigations on the spatio-temporal variations in LST across the city and its relationship with vegetation cover indicate that overexploitation of various resources demanded by a fast growing population has led to significant changes in LULC patterns in the last few years. Analysis of the changes in the urban energy balance and resulting UHI effect across the city under various urban growth scenarios and different proportions of green urban area are in progress. � 2016 SPIE.
Influence of different fractions of heavy metals on microbial ecophysiological indicators and enzyme activities in century old municipal solid waste amended soil
(2014) Tripathy S.; Bhattacharyya P.; Mohapatra R.; Som A.; Chowdhury D.
The ratios of microbial parameters/organic carbon indicated that inhibition of microbial growth. The study was carried out on an municipal solid waste dumping site, more than hundred year old, located on the outskirts of Kolkata metropolitan city in India to determine the concentrations of different forms of selected metals (Zn, Cu, Pb, Cr, and Ni), their effect on microbial ecophysiological parameters (microbial biomass, microbial metabolic quotient, microbial respiration quotient), fluorescein diacetate hydrolyzing activity and enzyme activities in solid waste amended soils. A sequential extraction technique was used to quantify water soluble, exchangeable, carbonate bound, Fe/Mn oxide bound, organic bound, and residual fractions of metals. Metal concentrations in the two most labile fractions (i.e. water soluble and exchangeable fractions) were generally low. The concentrations of different forms of metals, microbial ecophysiological parameters and enzyme activities were found to be significantly higher in solid waste amended soils compared to the normal background soil around the study area. Significant positive correlations were observed between the microbial parameters and organic carbon content of the waste amended soil. The contents of microbial biomass C, fluorescein diacetate and enzyme activities did not necessarily decrease with increasing heavy metal content, reflecting the importance of other environmental factors, e.g. differences in organic C content. The ratios of different microbial parameters with organic C were significantly negatively correlated with metal concentrations while inhibition increased with increased bioavailability of metals. Although the waste amended soils had significantly higher microbial biomass and activities than the background soil, due to higher organic matter content, the ratios of microbial parameters/organic carbon indicated that inhibition of microbial growth and activities had occurred due to metal stress. This indicates that the use of municipal solid wastes in agriculture would lead to destruction of soil quality in the long run. � 2014 Elsevier B.V..
Inhibition of acid mine drainage from a pyrite-rich mining waste using industrial by-products: Role of neo-formed phases
(2013) Sahoo P.K.; Tripathy S.; Panigrahi M.K.; Md Equeenuddin Sk.
In the present study, the potential use of the industrial waste residues, such as coal fly ash and clinker dust, was evaluated in inhibiting acid mine drainage generation from pyrite-rich wastes using non-saturated column experiments. Two columns (B and C) were filled with a mixture of industrial residues over pyrite-quartz sand (PS), while one column (A) used as the control was solely filled with PS. Artificial irrigation was maintained in each column by pouring Milli-Q water (pH 6.5). The leachate chemistry and the precipitation of neo-formed phases in the columns were examined. Based on the pH and concentration of SO4 2- in the effluent collected over a period of time, it can be inferred that pyrite dissolution was dominant in column A. In columns B and C, the addition of industrial waste produced a near neutral to alkaline leachate. At this pH, Fe released from pyrite oxidation was immediately depleted by precipitating into Fe-oxyhydroxide phases that likely coated the pyrite grains (termed as microencapsulation) which inhibited oxidation. This was supported from the scanning electron microscope observation and the geochemical modeling results. In addition, the precipitation of other neo-formed phases such as calcium carbonate and gypsum, along with the pozzolanic reactions of industrial wastes, possibly increased the cementation of fly ash particles leading to the development of a compact material, which prevented further oxidation by restricting infiltration and oxygen contact to the pyrite surface. This occurred best in column B; thus, it produced better quality of leachates than column C, though at the end both columns showed a significantly decreased concentration of Fe (up to 99.9 %) and other metals such as Cu, Cr, Pb, Zn, and Mn (lower values than the WHO permissible limits of drinking water) compared to control. � 2013 Springer Science+Business Media Dordrecht.
Interpretive structural modelling for critical success factors of R&D performance in Indian manufacturing firms
(2013) Tripathy S.; Sahu S.; Ray P.K.
PurposeIn order to enhance the performance of R&D in manufacturing organizations, the R&D managers need to identify the internal as well as the external factors that affect the R&D performance of manufacturing organizations in India. They need to understand the inter-dependencies of these factors. This paper seeks to identify the critical success factors for R&D in Indian manufacturing firms. Design/methodology/approachThere may be a number of factors that are critical for achieving acceptable R&D performance and these factors have been identified by a number of instruments or means, such as questionnaire surveys, brainstorming, and consolidation by Principal Component Analysis (PCA). A total of 14 factors have been identified by using principal component analysis and finally we have developed a structure of interrelationship among the identified critical success factors using an interpretive structural model. FindingsThe results show that R&D vision and direction and R&D oriented culture are the most important critical success factors (CSFs) and they have a great influence on the other CSFs. Though R&D vision and direction and R&D oriented culture are the short-term objectives, Indian manufacturing firms should be equipped with proper R&D management strategy to achieve the long-term objectives, such as achievement of revenue and profitability within a quick time frame. Practical implicationsAlthough R&D managers of Indian manufacturing firms are aware of various critical success factors, a systematic approach is required for identifying them, and as these factors may have complex interrelations between them for analyzing R&D performance in a manufacturing firm, it is essential that such an approach is in place. The hierarchy based ISM further defines those factors which are really critical and need more focus on the root causes of the success. In addition to that, the proposed ISM model acts as a good guideline in order to improve the performance of the manufacturing R&D organizations in India. Originality/valueThe paper provides an interpretive structural model to develop a map of the complex relationships and magnitude among identified critical success factors. � 2013, � Emerald Group Publishing Limited.
Investigation of influential factors of green supply chain management in Indian mining industries: An empirical study
(2017) Muduli K.; Biswal J.N.; Satapathy S.; Barve A.; Tripathy S.
Green supply chain management (GSCM) focuses on reduction of the adverse impacts of supply chain activities as well as a minimisation of energy and material usage. A successful implementation of GSCM is important for industries to increase economic-environmental performances. However, the GSCM adoption rate in Indian companies, particularly in the mining sector is not encouraging. There exists a set of factors that enhances GSCM adoption while others offer resistance to it. An attempt has been made to empirically test the relationship of various factors on GSCM implementation considering data collected from 144 respondents working in Indian mining industries, in which it was found that there is no difference in perception regarding the barriers of GSCM implementation. GSCM adoption in mining industries is initiated by factors like: 'society pressure', 'regulative pressure', 'investors' pressure'and 'eco-literacy among supply chain partners'. Further, practices like 'organising', 'initial environmental review' and 'continuous improvement' enhance GSCM effectiveness. Copyright � 2017 Inderscience Enterprises Ltd.
Land use and land cover change effect on surface temperature over Eastern India
(2019) Gogoi P.P.; Vinoj V.; Swain D.; Roberts G.; Dash J.; Tripathy S.
Land use and land cover (LULC) change has been shown to have significant effect on climate through various pathways that modulate land surface temperature and rainfall. However, few studies have illustrated such a link over the Indian region using observations. Through a combination of ground, satellite remote sensing and reanalysis products, we investigate the recent changes to land surface temperature in the Eastern state of Odisha between 1981 and 2010 and assess its relation to LULC. Our analysis reveals that the mean temperature of the state has increased by ~0.3 �C during the past three decades with the most accelerated warming (~0.9 �C) occurring during the recent decade (2001 to 2010). Our study shows that 25 to 50% of this observed overall warming is associated with LULC. Further we observe that the spatial pattern of LULC changes matches well with the independently estimated warming associated with LULC suggesting a physical association between them. This study also reveals that the largest changes are linked to changing vegetation cover as evidenced by changes to both LULC classes and normalized difference vegetation index (NDVI). Our study shows that the state has undergone an LULC induced warming which accounts for a quarter of the overall temperature rise since 2001. With the expected expansion of urban landscape and concomitant increase in anthropogenic activities along with changing cropping patterns, LULC linked changes to surface temperature and hence regional climate feedback over this region necessitates additional investigations. � 2019, The Author(s).
The may 21st, 2014 bay of Bengal earthquake: Implications for intraplate stress regime
(2015) Rai A.K.; Tripathy S.; Sahu S.C.
The northeastern part of the Indian Ocean, i.e. the Bay of Bengal (BoB) is located near some of the most complicated tectonic zones on the Earth. An earthquake of magnitude -6.0 occurred on 21 May 2014 near the coast of Odisha. Occasional moderate to large earthquakes in BoB highlight the need to study precise hypocentre locations, and focal mechanisms to understand the cause of intraplate seismicity in BoB. It is also important for seismic hazard and tsunami risk evaluation along the eastern coast of India. We present an analysis of the digital data of this earthquake recorded by regional and global networks of seismic stations. Our analysis of travel-times of P-and S-waves indicates that the epicentre of the earthquake is located between the Eighty Five East and Ninety East ridges. The focus of this earthquake was at a depth of -61 km, well below the lower boundary of the oceanic crust. The focal mechanism determined by modelling long period P-and SH-waveforms suggest an strike-slip motion along a NW-SE or NEE-SWWdirected fault or fracture. We interpret that the upper part of the BoB lithosphere is abnormally strong and brittle.
Metal behavior in sediment associated with acid mine drainage stream: Role of pH
(2013) Equeenuddin S.M.; Tripathy S.; Sahoo P.K.; Panigrahi M.K.
Metal mobilization from sediments in streams, which are severely impacted by the acid mine drainage (AMD), around Makum coalfield in North-eastern India was studied. Sediments in stream close to the collieries show low pH (up to 2.5) and very high electrical conductivity (up to 1816 ?S/cm). The stream sediments mainly consist of quartz, clay minerals, plagioclase with minor amounts of schwertmannite, goethite and jarosite. Concentrations of Cd, Cr, Mn, Ni and Zn exceed their respective crustal abundances in most of the areas. Fractionation study of metals reveals that in moderate to slightly acidic sediments, Cd and Cu are mainly associated with exchangeable and organic fractions respectively; Zn fractionated into Fe-Mn oxyhydroxides while Cr, Ni, Mn, Pb mostly into residual part. Higher concentrations of all metals are available in exchangeable fraction under strongly acidic environment; partitioning of Mn, Ni, Pb, Cu and Zn into exchangeable part is significantly controlled by pH. More Mn and Ni get partitioned into carbonate and Fe-Mn oxyhydroxides phases with increase in pH up to near-neutral value. Cadmium appears to be the most mobile elements. Apparent mobility and potential bioavailability of metals are in the order of Cd. > Pb. > Mn. > Ni. ? Zn. > Cu. > Cr. � 2012 Elsevier B.V.
Mineralogy of Fe-Precipitates and Their Role in Metal Retention from an Acid Mine Drainage Site in India [Die Mineralogie von Eisenablagerungen und deren Rolle in Metallr�ckhalteverm�gen auf einem durch saures Grubenwasser belasteten Gel�nde in Indien]
(2012) Sahoo P.K.; Tripathy S.; Panigrahi M.K.; Equeenuddin S.M.
Iron-rich precipitates from acid mine drainage (AMD) sites around the Jaintia Hills coalfield, India, were investigated. The ochreous precipitates mainly consist of schwertmannite, goethite, and jarosite. Sorption affinities suggest that Ni, Mn, Cr, Cd, Pb, and Zn are more significant in schwertmannite-bearing ochre than in more crystalline jarosite- and goethite-bearing ochres. The lower crystallinity and higher surface area of schwertmannite-bearing ochreous precipitate result in higher metal retention potential. Fe and Mn concentrations in water may also influence the sorption of metals in the precipitates. The results of the sequential extractions showed that metal mobility is mainly controlled by Fe and Mn oxyhydroxide phases. This information may aid understanding of the natural attenuation of trace metals by ochreous precipitates in AMD-contaminated water. � 2012 Springer-Verlag.
Multidimensional grid aware address prediction for GPGPU
(2019) Tripathy S.; Sahoo D.; Satpathy M.
GPGPUs are predominantly being used as accelerators for general purpose data parallel applications. Most GPU applications are likely to exhibit regular memory access patterns. It has been observed that warps within a thread block show striding behaviour in their memory accesses corresponding to the same load instruction. However, determination of this inter warp stride at thread block boundaries is not trivial. We observed that thread blocks along different dimensions have different stride values. Leveraging this observation, we characterize the relationship between memory address references of warps from different thread blocks. Based on this relationship, we propose a multidimensional grid aware address predictor that takes the advantage of SM level concurrency to correctly predict the memory address references for future thread blocks well in advance. Our technique provides a cooperative approach where information once learned is shared with all the SMs. When compared with the CTA-aware technique, our predictor enhances average prediction coverage by 36% while showing almost similar prediction accuracy. � 2019 IEEE.
A novel classification of handwritten digits using compressive sensing technique
(2016) Tripathy S.; Panda G.
This paper proposes a novel method of feature extraction for English digit recognition using compressive sensing. Compressive sensing provides the advantage of capturing the image by taking few measurements. These few measurements are capable of perfectly reconstructing the original image. Perfect reconstruction occurs because those few measurements capture the essence of the image. Hence, we used those few measurements as the features for digit recognition. Finally, we train two classifiers namely Support vector machine (SVM) and k-nearest neighbor (k-NN) with the resulting features and obtained performance of 95.0535% and 94.9300% respectively for both the classifiers on MNIST database. The purpose here is not to achieve a better accuracy than the other existing methods but to show that compressively sensed samples can be used as a feature for multiclass classification with more than 95% accuracy. After that we performed the same task by adding noise to the training images to show the robustness of compressively sensed features. At last we concluded that capturing the full image and then extracting features is as good as compressively sensing the image and perform pattern recognition on that compressed measurement. The results are quite good but on a new paradigm. � 2016 IEEE.
Response of trace metal redox proxies in continental shelf environment: The Eastern Arabian Sea scenario
(2015) Acharya S.S.; Panigrahi M.K.; Gupta A.K.; Tripathy S.
Major and trace elements (viz. Al, Si, Ca, Na, Fe, Ti, K, S, Mn, V, Cu, Zn, Mo, Ni, Th and U) along with organic carbon and nitrogen content were analyzed in the sediment samples of a gravity core (GC-08/SK-291; 12�34'N: 74�11.47'E) which lies within the upper edge of intense oxygen minimum zone (OMZ) of Eastern Arabian Sea. The aim was to determine how the geochemistry of the redox-sensitive elements (viz. V, Cu, Zn, Mo, Ni, and U) was influenced by the suboxic water column and bottom water condition and whether the sediments show a unique signature of such redox condition. The weathering intensity was also determined and the provenance of sediments has been inferred to discern the uniformity in sediment supply in the studied location. The chemical index of alteration (CIA), Chemical Index of Weathering (CIW) and Al-Ti-Zr ternary diagrams suggest low to moderate source area weathering of granodioritic to tonalitic source rock composition, which is similar to the regional geology of the continental mass nearby. The relative variations of major elements such as Si, Al and Ca suggest that the terrigenous fractions in the studied sediments are diluted by marine carbonates, unlike by biogenic opal, which is the case for most shelf regions of the world experiencing upwelling. The relative distributions of total organic carbon (TOC), total sulfur (TS) and total nitrogen (TN) suggest that the organic matter in the studied sediments is primarily of terrestrial origin irrespective of its presence in the deeper part of the shelf. We adopted the multi-proxy procedure for analyzing the redox condition prevalent during the deposition of sediments (e.g., enrichment of redox-sensitive elements, authigenic U, and ratios of trace metals such as U/Th, V/Cr, V/Mo, Ni/Co and (Cu+Mo)/Zn). The most striking result is a fully oxic signature reflected consistently by all redox proxies despite the occurrence of studied location within the OMZ of Arabian Sea. The redox proxies estimated from the bulk composition as well as the marine fraction of trace metals, do not reveal any significant difference in the depositional condition. The seasonal variation of O2 concentration seems to be the dominant factor which controls the response of the trace metals to the water column anoxia in the studied location. The major implication of the present study is that the trace element redox proxies alone are not always suitable to discern the redox condition of deposition in continental shelf sediments which are characterized by high sediment input from continents and significant seasonal variation of O2 concentration in the water column. � 2015 Elsevier Ltd.
Role of land state in a high resolution mesoscale model for simulating the Uttarakhand heavy rainfall event over India
(2016) Rajesh P.V.; Pattnaik S.; Rai D.; Osuri K.K.; Mohanty U.C.; Tripathy S.
In 2013, Indian summer monsoon witnessed a very heavy rainfall event (>30 cm/day) over Uttarakhandin north India, claiming more than 5000 lives and property damage worth approximately 40 billionUSD. This event was associated with the interaction of two synoptic systems, i.e., intensified subtropicalwesterly trough over north India and north-westward moving monsoon depression formed over the Bayof Bengal. The event had occurred over highly variable terrain and land surface characteristics. Althoughglobal models predicted the large scale event, they failed to predict realistic location, timing, amount,intensity and distribution of rainfall over the region. The goal of this study is to assess the impactof land state conditions in simulating this severe event using a high resolution mesoscale model. Theland conditions such as multi-layer soil moisture and soil temperature fields were generated from High Resolution Land Data Assimilation (HRLDAS) modelling system. Two experiments were conductednamely, (1) CNTL (Control, without land data assimilation) and (2) LDAS, with land data assimilation(i.e., with HRLDAS-based soil moisture and temperature fields) using Weather Research and Forecasting(WRF) modelling system. Initial soil moisture correlation and root mean square error for LDAS is 0.73and 0.05, whereas for CNTL it is 0.63 and 0.053 respectively, with a stronger heat low in LDAS. Thedifferences in wind and moisture transport in LDAS favoured increased moisture transport from ArabianSea through a convectively unstable region embedded within two low pressure centers over Arabian Seaand Bay of Bengal. The improvement in rainfall is significantly correlated to the persistent generation ofpotential vorticity (PV) in LDAS. Further, PV tendency analysis confirmed that the increased generationof PV is due to the enhanced horizontal PV advection component rather than the diabatic heatingterms due to modified flow fields. These results suggest that, two different synoptic systems merged bythe strong interaction of moving PV columns resulted in the strengthening and further amplification of the system over the region in LDAS. This study highlights the importance of better representation of the land surface fields for improved prediction of localized anomalous weather event over India. � Indian Academy of Sciences.
Spatio-temporal variations in ecosystem and CO 2 sequestration in coastal lagoon: A foraminiferal perspective
(2019) Barik S.S.; Singh R.K.; Jena P.S.; Tripathy S.; Sharma K.; Prusty P.
Seasonal variability in fresh water influx and ingression of sea water establish a unique transition zone in Asia's largest coastal lagoon � the Chilika lake. The seasonal variability in water and sediment input has significant impacts on the ecosystem influencing the rate of CO 2 sequestration. We have assessed the impact of seasonal variability on CO 2 sequestration using foraminiferal analysis and grain size data end member modeling. Lake floor sediment samples were collected seasonally, besides in situ measurements of physicochemical parameters of the lake bottom water at fixed stations influenced by seasonally variable fresh and saline water influx. Low electrical conductivity, pH of bottom water and absence of calcareous foraminifera suggest that the region proximal to the river mouth has fresh water ecosystem and has very limited role in CO 2 sequestration. The region near to the sea mouth experiences high energy condition and seasonally changes from brackish to marine water ecosystem are ideal for diversification and opportunistic populations of foraminifera, but not ideal for flourishing (high population) of calcareous foraminifera. Inter-mixing of fresh and saline sea water develops fresh to brackish water conditions with medium energy condition in the interior region. These locations are away from the river and sea mouths and have high calcareous foraminifera abundances, but low diversity along with high bottom water pH suggesting seasonal variations in the sinking of CO 2 . Like other shallow coastal areas, Ammonia beccarii and Ammonia tepida are the dominant calcareous species, but their smaller size suggests a seasonal stressed condition. The opening of new and artificial sea mouth has increased the inflow of sea water into the lagoon that maintains its brackish water conditions, suggested by significant increase in calcareous foraminifera abundance. The sinking of these calcareous foraminifera may enhance the rate of CO 2 sequestration and reduce degassing of dissolved carbon carried by the fresh water to the atmosphere. � 2019 Elsevier B.V.
Speciation of phosphorus in the continental shelf sediments in the Eastern Arabian Sea
(2016) Acharya S.S.; Panigrahi M.K.; Kurian J.; Gupta A.K.; Tripathy S.
The distributions of various forms of phosphorus (P) and their relation with sediment geochemistry in two core sediments near Karwar and Mangalore offshore have been studied through the modified SEDEX procedure (Ruttenberg et al., 2009) and bulk chemical analysis. The present study provides the first quantitative analysis of complete phosphorus speciation in the core sediments of the Eastern Arabian shelf. The chemical index of alteration (CIA), chemical Index of Weathering (CIW) and Al-Ti-Zr ternary diagram suggest low to moderate source area weathering of granodioritic to tonalitic source rock composition, despite the intense orographic rainfall in the source area. Due to the presence of same source rock and identical oxic depositional environment, the studied sediments show the same range of variation of total phosphorus (24 to 83 ?mol/g) with a down-depth depleting trend. Organic bound P and detrital P are the two major chemical forms followed by iron-bound P, exchangeable/loosely bound P and authigenic P. The authigenic P content in the sediments near Mangalore coast varies linearly with calcium (r = 0.88) unlike that of Karwar coast. The different reactive-phosphorus pools exhibit identical depleting trend with depth. This indicates that the phosphorus released from the organic matter and Fe bound fractions are prevented from precipitating as authigenic phosphates in the deeper parts of the sediment column. The low concentration of total P, dominance of detrital non-reactive fraction of P and inhibition of formation of authigenic phosphate result in the absence of active phosphatization in the Eastern Arabian Shelf in the studied region. High sedimentation rate (35-58 cm/kyr) and absence of winnowing effect appear to be the dominant factor controlling the P-speciation in the studied sediments. � 2016 Elsevier Ltd.
Utilization of ochre as an adsorbent to remove Pb(II) and Cu(II) from contaminated aqueous media
(2014) Sahoo H.B.; Tripathy S.; Equeenuddin S.M.; Sahoo P.K.
The ability of ochre to remove Pb(II) and Cu(II) from aqueous media has been studied by batch sorption studies varying the contact time, initial metal concentration, initial solution pH and temperature to understand the adsorption behaviour of these metals through adsorption kinetics and isotherms. The pH of the solution and the temperature controlled the adsorption of metal ions by ochre and rapid uptake occurred in the first 30 min of reaction. The kinetics of adsorption followed a pseudo-second-order rate equation (R 2 > 0.99) and the isotherms are well described by the Freundlich model. Adsorption of metals onto ochre is endothermic in nature. Between the two metals, Pb(II) showed more preference towards the exchangeable sites on ochre than Cu(II). This study indicates that ochre is a very effective adsorbent in removing Pb(II) and Cu(II) from the aqueous environment with an adsorptive capacity of 0.996 and 0.628 mg g-1 and removal efficiency of 99.68 and 62.80 %, respectively. � 2013 Springer-Verlag Berlin Heidelberg.