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Deep-sea floors act as reservoir for various marine mineral deposits rich in strategic metal resources important to growth of nation’s economy, national security and the emerging blue economy. Central Indian Ocean Basin (CIOB) is a region with vast marine mineral deposits with a congregation of metals in the form of nodules known as polymetallic nodules (PMN). Government of India signed a 15-year contract with International Seabed Authority (ISA) for exploration of PMN from CIOB. Extensive survey and other scientific developmental activities have been carried out in 75,000km2 area retained by India in CIOB. To conduct mining activities prior to assessment of impact on environment would remark an unwise undertaking. Deep sea mining operation will inevitably impact the surrounding ecosystem due to removal and separation of nodules from soft sediments and increases in suspended finer particles from the altered deep-sea sediment. Disturbances to sediments will have impact on the speciation (labile/inert complexes) of sedimentary metal complexes and may increase metal mobility and bioavailability in marine ecosystem. Study on the possible impact of deep-sea PMN mining requires systematic scientific investigation.This study presents kinetic speciation of metal in surface sediments and their downcore profile.To understand the stability and lability of metals, kinetic speciation study is carried out using ethylenediaminetetraacetic acid (EDTA) as the extracting reagent. Kinetic fractionation studies were performed from two sediments core collected from Test mining site (TMS) and Reference mining site (RMS) in CIOB to determine the metal-sediment complexes and their fate, mobility and bioavailability. Concentration of labile metals complexes and their dissociation rate constant in deep sea sediment can be an index for their bioavailability. It was found that total concentration of Cu and Co gradually decreases, whereas Ni increases in the study area The observed results suggest that the stability of metals-sediment complexes for Cu, Ni, and Co with respect to the depth of the sediment cores gradually increased in the study area. This study suggests that disturbances of deep-sea sediments during PMN mining may not increase labile metals complexes at water-sediment interfaces in the surrounding marine ecosystem. However, results obtained from two sediment cores from Test mine site and Reference mine site respectively may not satisfy representation of the entire 75,000km2 CIOB. Further study is recommended to provide better understanding of the impact of mining activities on marine ecosystem.

Understanding mercury (Hg) dynamics in an estuarine system is vital because of its potential toxicity to the ecosystem. India is the second largest producer of atmospheric Hg, and the dynamics of Hg are poorly understood in tropical estuarine systems. This study describes the distribution, speciation and mobility of Hg in a monsoon-fed tropical estuarine system in India (Mandovi estuary, East coast of India) during dry period (November-March) when the pollutants stay for a long time within the estuary due to negligible river discharge.This study presents the impact of changing physicochemical parameters of water column (such as pH, dissolved oxygen, salinity) and sediment [such as texture, sedimentary organic matter (SOM), molar carbon to nitrogen ratio and chemical characterisation of SOM] on distribution and speciation of Hg in the surface sediments, porewater and water column along the length of the estuary (from upstream to downstream). There was a significant increase in concentration of sedimentary methylmercury (MeHg)(a neurotoxin) with an increase in total sedimentary Hg concentration in the estuary. However, concentration of sedimentary MeHg was found to decrease with increasing concentration of SOM depend on the nature of SOM. Results from an equilibrium-based model (Visual MinteQ) showed that a significant concentration of Hg was associated with type-II fulvic acid, and reduction of Hg(II) was more in presence of type-II humic acid.This study showes that the reduction and methylation process of Hg control Hg distribution in the study area, and estuarine sediment is one of the primary sources of dissolved Hg in the water column.

Sedimentary organic matter (SOM) plays an important role in hosting and reducing HgII in marine/estuarine sediment. This study provides a better understanding on the influence of nature of SOM, in regulating sedimentary mercury (Hg) and elemental mercury (Hg0) distribution, and speciation in the Zuari and Mandovi Estuaries that are representative of monsoon fed tropical estuaries, located in the central west coast of India. Salinity of the overlying water column controlled the physical and chemical characteristics of SOM in the estuarine systems. The high molecular weight (MW) SOM dominated at the mid and upstream (low salinity region) of the estuaries, whereas, the low MW SOM prevailed at the downstream (high salinity region). Sediment Hg showed more affinity towards the SOM of high MW. Increasing MW of SOM increased total sedimentary HgT in both the estuaries. SOM with low MW in the estuarine sediment displayed a negative relationship with the sediment Hg concentration. Distribution of Hg0 concentration in the estuarine sediment suggests that reduction of HgII in presence low MW SOM was a dominant process. It was also found that distribution and speciation of Hg0 in the estuarine sediment depends on the quantity, quality of the SOM, and the total sediment Hg loading. This study demonstrated that the competition between Hg-SOM complexation and HgII reduction by SOM controls HgII/Hg0 distribution in tropical estuarine sediment systems.

There is limited knowledge regarding seawater intrusion on Hg distribution in monsoon fed tropical estuarine systems during dry season (February to May). This study examined the influence of resuspension of estuarine sediment and intrusion of Hg bound SPM (HgSPM) (by the tide) from the outside of an estuary in controlling distribution, mobility, and bioavailability of Hg within the estuarine systems during the dry season. This investigation was carried out in the Mandovi estuary, a monsoon fed tropical estuary from the central west coast of India. Total Hg concentrations in the water column showed an increasing trend from upstream to downstream of the estuary. The concentration of Hg in the water column of the estuary was much below the concentration recommended by the EPA for aquatic life ambient water quality. Dissolved Hg (HgDissolved) was found to associate mainly with the higher molecular weight fraction of dissolved organic matter (DOM). A significant portion of the total Hg in the water column was present as HgSPM. The average bio-accumulated Hg concentration in edible oyster was high (collected from the estuary) during the dry season compared to the wet season (June to September). This study reveals that resuspension of Hg associated finer sediment particles and intrusion of HgSPM from the outside of the estuary may increase bioavailability of Hg in the Mandovi estuarine systems during the dry season. It is suggested that Hg bioaccumulation in commercially important biological species from different tropical estuarine system may increase during the dry season. The outcome of this research can be useful for policy making and to take proper decision to reduce and control Hg/toxic metals pollution (if any) in tropical estuarine system.

Ballast water transport is considered as one of the major vectors for dispersal of microplastics around the global oceans. In this commentary, a simple, inexpensive solution has been proposed to reduce microplastic pollution and its mobility via ballast water. A screening chamber (with stainless steel three layered mesh) is proposed to be attached to the existing Ballast Water Treatment Systems (BWTSs) in cargo ships to filter back-flushed sea water from BWTSs. The three layered screens (500, 300 and 100 μm) will not only avoid clogging and easy separation of different size groups of microplastic particles but also help in smooth discharge of water to the sea. This technique is expected to remove a large number of microplastic particles (ranging from 0.0015 to 1020 million) from a single voyage. The proposed chamber may help to collect 0.0003-204 metric tons of particles/day, depending upon the geographical location of ballast intake in the global ocean. These estimations were made by considering a daily turnover of 0.033 billion tonnes of ballast water globally. This proposed screening chamber attached to the existing BWTSs in cargo ships, along with other region-specific ocean cleaning initiatives, will help in mitigating microplastic pollution in the global ocean.

Objectives The modified Naranjo algorithm assesses the physician assigned cause-effect relationship for homeopathic medicines. It is being adopted in homeopathy researches, but not yet validated systematically. We intended to validate the modified Naranjo algorithm by examining its psychometric properties. Methods An online survey sought agreement of 25 experts on the 10 items of the tool on 5-point agreement scale. Next, 285 responses from collected prospectively from chronic cases enrolled under the clinical verification program of the council in 2018 were subjected to testing of construct validity using exploratory principal component analysis (PCA). Confirmatory factor analysis (CFA; n=150) was performed to verify the goodness-of-fit of the model. Reliability was tested using internal consistency, test–retest reliability, and inter-rater reliability by kappa statistics. Results Experts’ responses mean values were 4 or higher (i.e. responses were relevant) and standard deviations were less than 1 (i.e. less heterogeneous). In PCA using varimax, all the items loaded above the pre-specified value of 0.4 and identified 4 components explaining 64.1% of variation. The goodness-of -fit of the 4-component CFA model was acceptable (chi-square 89.253, p Conclusions Statistical evaluations indicate that the modified Naranjo algorithm is useful, but needs improvement.

Geochemical fractionation study of cadmium (Cd) in combination with equilibrium based chemical speciation modelling (visual MINTEQ) in finer sediment samples (silt and clay portion), provided a better description of Cd bioavailability for sessile organisms (like oysters) in the Zuari estuary, west coast of India. A substantial fraction of total Cd in the finer sediment samples was present as water soluble, exchangeable and carbonate/bicarbonate forms and showed a strong positive relationship with Cd-bioaccumulation in oysters (Magallana sp.) from the study area. Cadmium bioaccumulation (ranged from 2.4–7.9 mg·kg−1) in soft tissues of the edible oyster was high (higher than the maximum permissible limit for human consumption) throughout the study period of one year. Equilibrium based speciation modelling suggest that sedimentary CdCl2, CdCl+ and Cd2+ were responsible for Cd bioaccumulation in the oysters. This study describes that combination of geochemical fractionation study of metals in finer sediments and equilibrium based speciation modelling can be very useful in comprehending link between sedimentary metal speciation and its bioaccumulation in sessile organisms.

This is the first study to comprehend copper (Cu)-dynamics in a monsoon fed Indian estuarine system (the Mandovi estuary from the central west coast of India). Distribution and speciation of Cu in estuarine sediment, pore water, suspended particulate matter (SPM) and water column was used to understand geochemical cycling of Cu in the estuary. Geochemical fractionation study reveals that sedimentary organic carbon (Corg) was the major hosting phase for non-residual Cu in the sediments. Experimental analysis and chemical speciation modelling suggests that leaching of sedimentary Cu2+, CuCO3 and a fraction of Cu-Corg complexes increased Cu-concentrations in the pore water towards the downstream of the estuary. Dissolved Cu concentration in overlying water column was observed to increase with increasing Cu concentrations in the pore water. This study suggests that chemical speciation of sedimentary Cu play key role in controlling its distribution and dynamics in the tropical estuarine system during dry period.

Accumulation of toxic metals and indigenous bacteria in oyster, (Saccostrea cucullata) and their impact on antioxidant enzyme activities in the biological system was studied and used to provide snapshot of environmental condition in different tropical estuarine systems. The sedimentary Cd, Pb, and Hg concentration varied from 0.1 to 1.8, 22.0 to 98.0, and 0.03 to 0.11 mg kg−1 (dry wt.) respectively. The bioaccumulated Cd, Pb, and Hg concentration in the oysters ranged from 3.6 to 9.0, 0.03 to 8.0, and 0.06 to 0.1 mg kg−1 (dry wt.) respectively. In the oyster, the Cd concentration was well above the safe limit whereas the Pb and Hg concentrations were below the safe limit recommended by the European Commission (EC No. 1881/2006) for human consumption. The MPN value in the raw oyster for fecal coliforms (33–110 × 103/100 g) exceeded the United States Food and Drug Administration (USFDA) approved limits. Increase in antioxidant enzymes (catalase, superoxide dismutase, glutathione-s-transferase, and metallothionein) activities with increasing pollutants loading was observed. The activities of antioxidant enzymes in the oyster were found to be very useful tool for evaluating environmental condition in any tropical estuarine systems.

Impact of varying concentrations and counts of toxic metals and indigenous bacteria on antioxidative defense system in edible oyster, Saccostrea cucullata, collected from four tropical estuarine systems of Goa (west coast of India), are presented in this study. Relatively high abundance of bacteria was estimated from the oysters especially during monsoon season (June–September). Density of total and fecal coliforms were about 24 times higher in the organism than the surrounding water (average TC: 4360 and FC: 3475 MPN 100 ml−1). Sedimentary Cd, Pb, and Hg concentrations varied from 0.12 to 0.48, 19.28–102.48, and 0.03–0.13 mg kg−1 (dry wt.) while, bioaccumulation of Cd, Pb, and Hg in the oysters ranged from 5.17 to 10.6, 0.18–7.99, and 0.06–0.22 mg kg−1 (dry wt.) respectively. Higher degree of pollution and moderate ecotoxicological risks with increasing toxicity (36–37%) was observed in two of the tropical estuaries. Biomarker response in the oysters was somewhat inconsistent with pollution load in the estuarine systems. Elevated environmental stress was observed during pre-monsoon (March–May) followed by the monsoon period. Sedimentary metals were identified as predominant inducers of antioxidative defence system in oysters from the study areas. This study suggests that, biomarker can be useful in assessing the combined effects of metal and bacterial contaminations on native oysters and in evaluating environmental quality in tropical estuarine systems.

Two independent analytical methods (kinetic and sequential extraction protocols) were used to understand the distribution, stability, and lability of Pb-sediment complexes in Indian continental shelf. The concentrations of sedimentary Pb varied from 12.0±0.6 to 30.4±0.1mg·kg-1 and 15.9±0.3 to 36.7±0.4mg·kg-1 in the western and eastern shelf of India respectively. The kinetic extraction study showed that higher proportion of labile Pb-complexes were present in the eastern shelf sediments (~24% of total Pb) than the western shelf sediments (~14% of total Pb). The sedimentary organic matter was found to regulate lability of sedimentary Pb complexes. The sequential extraction study suggested that Fe/Mn oxyhydroxide were the primary hosting phase for labile Pb complexes. This study showed that water soluble, exchangeable, carbonate/bicarbonate-Pb complexes in the sediments was labile. This study provides a better physicochemical description of stability or lability of Pb complexes in the coastal sediment of India.

India is an industrial giant with one of the fastest growing major economies in the world. Primary energy consumption in India is third after China and the USA. Greater energy production brings the burden of increasing emissions of mercury (Hg). India ranks second for Hg emissions. Rising atmospheric Hg release, high Hg evasion processes, and increasing monomethylmercury (highly neurotoxin) accumulations in marine food products increase the potential for human and ecosystem Hg exposure. Hg has been identified to increase the risk of getting Alzheimer's disease (AD). There are increasing reports of AD and dementia in different age groups in India. The relationship between increasing Hg exposure and increasing neurodegenerative disorder in India is not known. This commentary points to the need for better understanding of the relationship between Hg release and AD in India, and other countries, and how to protect human health and the environment from the adverse effects of Hg.

Highlights • India is industrializing rapidly with significant releases of Pb. • Increase in anthropogenic Pb input to Indian shelf occurred over last 40 years. • Sediment leachate Pb isotopes used to assess anthropogenic Pb inputs • Sources of Pb in eastern and western shelves of India were different. • Inland coal combustion and heavy industries are major sources of Pb. India is industrializing rapidly and with this there comes higher releases of contaminants into the environment. Change in Pb deposition over the last century on the eastern (off Andhra Pradesh) and western (off Karnataka) shelves of India was investigated based on the data extracted from two sediment cores covering the past ~114 and ~145 yrs. The variations of the total Pb content, its enrichment factor, and concentrations of non-residual Pb in both the sediment cores document that there was a gradual increase in anthropogenic Pb input into the coastal sediments of India over the last century. Sediment leachates were used to monitor the increase in anthropogenic Pb input and its Pb isotope composition. The anthropogenic end member composition of the western shelf sediment location (206Pb/207Pb: 1.105; 206Pb/208Pb: 2.149) was significantly less radiogenic than the eastern shelf isotopic composition (206Pb/207Pb: 1.145; 206Pb/208Pb:2.120). A binary mixing model suggests that Pb emitted from the heavy industries (e.g., ore mining, Pb processing and smelting plants) of India has been the major source of anthropogenic Pb to the sediments of western continental shelf. In contrast, the isotopic signatures suggest that coal combustion is responsible for elevated anthropogenic Pb levels in the sediments from the eastern shelf of India.

Influences of post depositional changes of sedimentary organic matter (SOM) on chromium (Cr) speciation in continental slope sediments from the east and west coast of India are presented in this study. Average concentrations of total sedimentary Cr (CrT) in the slope areas of both the coasts were not elevated and ranged from 56.8 to 163 mg·kg−1 (avg. 97.3 ± 28.3 mg·kg−1). The geology of adjacent land masses influenced sedimentary Cr concentration in the slope areas. Geochemical fractionation study showed that a major fraction (51.6–159 mg·kg−1; avg. 89.6 ± 24.3 mg·kg−1) of the total sedimentary Cr was present in residual part of the sediments. Prime hosting phase for non-residual sedimentary Cr was oxidizable binding phase (SOM) (1.4–23.9 mg·kg−1; avg. 6.7 ± 6.3 mg·kg−1) followed by reducing binding phase (Fe/Mn-oxyhydroxide phase) (0.1–1.7 mg·kg−1; avg. 0.7 ± 0.3 mg·kg−1). Concentration of Cr (VI) in the slope sediments, varied from 0.2 to 8.3 mg·kg−1 (avg. 1.2 ± 1.0 mg·kg−1), was also predominantly associated with the SOM. The δ13Corg values of the SOM (ranged from −19.4 to −21.4‰; avg. −20.3 ± 0.5‰) suggests that they were derived from marine sources. Based on molar C/N ratio (ranged from 6.3–12.9; avg. 9.0 ± 2.0), the SOM were classified as labile organic matter. Increasing molar C/N ratio in the studied sediments was used as a proxy to reflect post depositional changes of the SOM. Association of normalized Cr (VI) (with respect to CrT) increased with increasing SOM concentration by 0.008 mg·kg−1. One unit increase of sedimentary molar C/N ratio was found to increase normalized Cr (VI) (w.r.t. CrT) by 0.003 mg·kg−1 in the sediments. This study suggests that post-depositional changes of SOM may increase Cr binding capacity and control its speciation and mobility in marine sediment system.

Coastal waters receive large amounts of nutrients and pollutants from different point and nonpoint sources through bays and estuaries. Excess supply of nutrients in coastal waters may have detrimental effects, leading to hypoxia and anoxia from eutrophication. Reduction in concentrations of excess nutrients/pollutants in bays/estuarine system is must for healthy coastal ecosystem functioning. Conservations of bays, estuaries and coastal zones are must for sustainable development in any maritime country. Excellent ability of oyster in removing and controlling the concentrations of nutrients, pollutants, suspended particulate matters from bays and estuarine waters stimulated me to provide a viewpoint on oyster reef restoration in controlling nutrient/heavy metals fluxes and marine coastal pollution around India. Oyster reefs restoration may decrease nutrient and heavy metals fluxes in coastal waters and reduce the intensity of oxygen depletion in the coastal Arabian Sea (seasonal) and Bay of Bengal. However, extensive research is recommended to understand the impact of oyster reef restoration in controlling coastal pollution which is essential for sustainable development around India.

This study investigated the influences of varying dissolved oxygen (DO) levels in overlying bottom water, sediment grain size, total sedimentary organic carbon (C org ), and total sedimentary sulfide concentrations on the distribution and speciation of mercury (Hg) and methylmercury (MeHg) in coastal sediments from a transect across the oxygen minimum zone (OMZ), in the Arabian Sea, off the west coast of India. The C org concentration increased with the increasing finer particulate in the sediments and decreasing DO level of the overlying bottom water. Increasing concentrations of C org (under suboxic overlying water) increased accumulation of Hg in the sediments. However, depleted DO level of the overlying bottom water did not enhance the concentration of MeHg in the underlying sediments. The concentration of sedimentary MeHg decreased with the increasing C org and total Hg concentrations in the sediments. The nature of the C org played a key role in controlling the distribution and speciation of Hg in the sediments. This study suggests that increased concentrations of inert C org (with C/N > 11) increased Hg-C org complexation and decreased the net methylation rate of Hg in the sediments from the study area. Overall, the nature of C org controlled Hg-methylation in the surface sediments of the OMZ in the Arabian Sea.

Competing ligand exchange method (CLEM) in conjunction with direct mercury analyzer (DMA) was found to be a useful method for kinetic speciation study of (mercury–humic acid) Hg–HA complexes in aqueous systems. Ambersep GT74 (containing a thiol functional group) was used as a suitable competing ligand for this study. The CLEM/DMA was used to estimate lability and dissociation rate constant of Hg–HA complexes in aquatic systems. Influences of pH, metal loading and varying major cation (Ca2 +) concentrations on Hg–HA complexes were investigated. Concentration of dynamic Hg–HA complexes gradually increased with increasing Hg loading in the system. The dissociation rate constant (kd1) of labile Hg–HA complexes were found to vary from 4.3 × 10− 3 s− 1 to 9.2 × 10− 3 s− 1 with increasing Hg loading from 1.0 × 10− 8 M to 1.42 × 10− 7 M. The concentrations of Hg–HA complexes with low thermodynamic stability were found to be similar at pH 4 and 5 (~ 59% and 58% of the total Hg with kd1 values of ~ 2 × 10− 3 and 1.7 × 10− 3 s− 1, respectively). The complexation of Hg with HA was found to increase with increasing pH from 4 to 7. The concentration of inert complexes (c2) with dissociation rate constant (kd2) gradually increased with increasing pH. Increasing concentration of Ca2 + in the model solutions increased the concentrations of Hg–HA dynamic complexes in the system. This finding suggests that the Hg–HA bond is predominantly ionic in nature. It suggests that Ca2+ ions screen out Hg2+ ions from undergoing complexation reaction with HA.

Recommender systems help customers to choose right product or service from large number of alternatives available on Internet. In recent time, trust becomes an important issue in designing effective recommender systems. In this paper we have studied the role of trust and distrust in designing recommender systems. General Terms E-Commerce, Information Retrieval, Web Mining.

Metal speciation study in combination with major element chemistry of deep sea sediments provided possible metal enrichment pathways in sediments collected from environmentally different locations of Central Indian Ocean Basin (CIB). Metal speciation study suggests that Fe–Mn oxyhydroxide phase was the major binding phase for Ni, Cu and Pb in the sediments. The second highest concentrations of all these metals were present within the structure of the sediments. Easily reducible oxide phase (within the Fe–Mn oxyhydroxide binding phases) was the major host for all the three metals in the studied sediments. Major element chemistry of these sediments revealed that there was an increased tendency of Cu and Ni to get incorporated into the deep sea sediment via the non-terrigenous Mn-oxyhydroxide fraction, whereas, Pb gets incorporated mostly via amorphous Fe-hydroxides into the sediment from the CIB. This is the first attempt to provide an insight into the mechanism of metal enrichment in sediment that host vast manganese nodule.

Sedimentary organic matter (SOM) plays an important role in hosting and reducing Hg

Context: Clinical verification is an ongoing research program of the Council that verified many rare homoeopathic drugs. Aim: This study was carried out to clinically verify the "symptomatology" of Cynodon dactylon and to ascertain the prevalence of symptoms in the "improved" and "not improved" groups. Materials and Methods: The study was a multicenter, open, observational study. A total of 462 patients were enrolled after matching with the available symptom, compendium of the drug, and eligibility criteria in seven units/institutes of the Council. The medicine was prescribed in 6C, 30C, 200C and 1M potencies as per the need of each patient, following homoeopathic principles and the protocol developed by the Council. The collected data were presented in terms of descriptive statistics. Prevalence of the symptoms in the responding and nonresponding population was compared using Chi-square test or Fisher′s exact test, as appropriate. Results: A total of 340 complete cases were analyzed; male/female was 204/136; mean age was 29.7 years. There were "clinical successes" in 274 (80.6%) cases and "failures" in 66 (19.4%), judged subjectively by the physicians. A minimum of two prescriptions was considered for pick-listing each symptom as per protocol. The number of symptoms verified was as follows: proving symptoms (n = 43), symptoms from other literature (n = 10), and new clinical observations (n = 57). Conclusions: A total of 53 recorded symptoms were verified and 57 new clinical symptoms were identified. Further replication and estimation of likelihood ratio in general practice settings are crucial for confirmatory inclusion of the symptoms in homoeopathic literature.

Aims: This study was done to clinically verify the symptomatology of Formic acid by ascertaining the symptoms improved during verification and to incorporate new findings (if any) to the known symptomatology of Formic acid. Methods: A multicentric observational clinical verification study was conducted at nine research centers of Central Council for Research in Homoeopathy to verify the proving symptoms of rarely used medicine, Formic acid. Two hundred and seventy participants having symptomatological similarity with Formic acid were included and prescribed in 6C, 30C, 200C, and 1M potencies, as per need of each case. The data were compiled in a specially designed Excel spreadsheet for further analysis. The collected data were presented in terms of descriptive statistics. Prevalence of the symptoms in the responding and nonresponding population was compared using Chi-square or Fisher's exact test. Results: Out of 266 followed up patients, 215 cases responded (80.8%) with 95% confidence interval of 0.75-0.85. The number of symptoms verified was as follows: proving symptoms (n = 11) and new observations (n = 22). The widely emerged new general symptoms, i.e., clean tongue, disturbed sleep, loose stool, tastelessness, and profuse sweat may be worth consideration during prescription of Formic acid. Conclusions: The proving symptoms of Formic acid could be verified clinically, but the correlation of patient-specific symptom needs cautious interpretation. Further replication on larger sample and estimation of likelihood ratio in real-time clinical practice are needed.

A linkage between Cd speciation in sediments and its bioaccumulation in edible oyster (Crassostrea sp.) from a tropical estuarine system was established. Bioaccumulation of Cd in edible oyster increased with the increasing lability and dissociation rate constants of Cd-sediment complexes in the bottom sediments. Total Cd concentration in sediment was not a good indicator of Cd-bioavailability. Increasing trace metal competition in sediments increased lability and bioavailability of Cd in the tropical estuarine sediment. Low thermodynamic stability and high bioavailability of Cd in the estuarine sediment were responsible for high bioaccumulation of Cd in edible oysters (3.2-12.2mgkg(-1)) even though the total concentration of Cd in the bottom sediment was low (0.17-0.49mgkg(-1)).

Distribution of metals in different binding phases of estuarine sediments provides chemically significant description of metal-sediment interactions. This study describes the influences of ligand field stabilization energy (LFSE), Jahn-Teller effect, and water exchange rate (k-w) on metal distribution in different binding phases of estuarine sediments. It was found that Cu had highest affinity for organic binding phases in the studied sediments followed by Ni and Pb. However, Pb showed strong association with Fe/Mn oxide phases followed by Ni and Cu. Faster k-w of Cu (II) (1 × 10(9) s(-1)) increased the rate of complex formation of Cu(2+) ion with ligand in the organic phases. The Cu-ligand (from organic phase) complexes gained extra stability by the Jahn-Teller effect. The combined effects of these two phenomena and high ionic potential increased the association of Cu with the organic phases of the sediments than Ni and Pb. The smaller ionic radii of Ni(2+) (0.72 Å) than Pb(2+) (1.20 Å) increase the stability of Ni-ligand complexes in the organic phase of the sediments. High LFSE of Ni(II) (compared with Pb(2+) ions) also make Ni-organic complexes increasingly stable than Pb. High k-w (7 × 10(9) s(-1)) of Pb did not help it to associate with organic phases in the sediments. The high concentration of Pb in the Fe/Mn oxyhydroxide binding phase was probably due to co-precipitation of Pb(2+) and Fe(3+). High surface area or site availability for Pb(2+) ion on Fe oxyhydroxide phase was probably responsible for the high concentration of Pb in Fe/Mn oxyhydroxide phase. Increasing concentrations of Cu in organic phases with the increasing Cu loading suggest that enough binding sites were available for Cu in the organic binding phases of the sediments. This study also describes the influence of nature of sedimentary organic carbon (terrestrial and marine derived OC) in controlling these metal distribution and speciation in marine sediment.

Organic matter (OM) was found to play an important role in controlling mercury (Hg) distribution and speciation in estuarine sediment of the Vembanad Lake. The sedimentary organic carbon (OC) from the northern part of the lake was influenced mainly by marine in situ biological production. However, the sedimentary OC was mainly of terrestrial origin in the southern part of the lake. The average concentrations of Hg in the sediments were relatively higher in the northern part (ranging from ~ 6.5 to 172.0 μg/kg, with an average concentration of 59.6 μg/kg) than the southern part of the lake (ranging from ~ 6.8 to 114.0 μg/kg with an average concentration of 49.7 μg/kg). This study suggests that nature and source of sedimentary OC probably control Hg speciation in the Vembanad Lake system. Speciation study of Hg suggests that a major part (55–90%) of the total Hg was mainly associated with organic phases in the sediment. The variation in concentrations of organic matter bound Hg with the increasing Hg/TOC ratio suggests that more Hg binding sites were available in the sediment from the northern part of the lake but not in the southern part of the lake. Anthropogenic activities were responsible for the higher Hg content in the sediment collected from the northern part of the lake. It is suggested that the strong affinity of sedimentary total nitrogen (TN) for Hg is independent of its source. The sedimentary OM was found to control Hg distribution in different size fraction of the estuarine sediment.

Sequential extraction study was performed to determine the concentrations of non-residual metal-complexes in the mangrove sediments from the Divar Island, (west coast of India). Accumulation of metal in the mangrove roots (from the same location) was determined and used as an indicator of bioavailability of metal. An attempt was made to establish a mechanistic linkage between the non-residual metal complexes and their bioavailability in the mangrove system. The non-residual fractions of Cu and Ni were mainly associated with Fe/Mn oxyhydroxide and organic phases in the sediments. A part of these metal fractions were bioavailable in the system. These two phases were the major controlling factors for Ni speciation and their bioavailability in the studied sediments. However, Cu was found to interact more strongly with the organic phases than Ni in the mangrove sediments. Organic phases in the mangrove sediments acted as buffer to control the speciation and bioavailability of Cu in the system.

Impact of pH variation of overlying water column on transport and transformation of Cu-sediment complexes in the bottom mangrove sediments was investigated by using different metal extraction studies. The total Cu concentration in the studied sediments varied from ~64 ± 1 to 78 ± 2 mg·kg−1. The sequential extraction study showed that a major part of the sedimentary Cu (85–90% of the total sedimentary Cu) was present within the structure of the sediments with minimum mobility and bioavailability. The redistribution of non-residual Cu among the different binding phases of the sediments was observed at different pH. It was found that Cu shifted from the different non-residual binding phases to the organic binding phase of the sediments at higher pH. Partial leaching of sedimentary Cu-SOM complexes (with increasing stability as determined by kinetic extraction study) was observed at higher pH. This study infers that increase in pH of overlying water column may release Cu-SOM complexes and increase the mobility of Cu-complexes in mangrove systems.

This study investigated the linkage between mercury (Hg) speciation in the surficial sediments from a mangrove ecosystem of the Zuari Estuary, west coast of India, with Hg bioaccumulation in gastropods collected from the same area. Multiple operationally defined protocols and methods were used for determination of Hg speciation study in the mangrove sediments. Moderately low concentrations of Hg were observed in the sediments, ranging from 37.3 ± 1.9 to 79.6 ± 4.0 µg/kg. Geochemical fractionation showed that a significant part of sedimentary Hg was present within the structure of the sediment (residual fraction) and not bioavailable. Non-residual Hg was primarily associated with oxidizable (sedimentary organic matter (SOM) or sulfide) binding phase of the sediments, and ranged from 9.2 ± 0.3 to 78.5 ± 3.9 µg/kg. Concentration of methylmercury (MeHg) (a neurotoxin) in the sediments varied from 1.7 ± 0.1 to 4.4 ± 0.1 µg/kg. l-Cysteine, a suitable complexing ligand, extractable Hg concentration in the sediments ranged from 4.3 ± 0.1 to 15.9 ± 0.3 µg/kg. Statistical analysis suggested that MeHg was adsorbed on Fe/Mn oxyhydroxide phases in the sediments. l-Cysteine was found to extract sedimentary MeHg and thermodynamically less stable Hg-SOM complexes from the sediments. Concentrations of bioaccumulated Hg in soft tissues of the gastropod, Pirenella cingulata, ranged from 57.6 ± 4.4 to 224.4 ± 7.2 µg/kg. Positive correlations existed between the concentration of bioaccumulated Hg in the gastropods and the concentrations of Hg associated with the oxidizable phase, sedimentary MeHg and l-Cysteine extracted Hg in the sediments. This study indicated that operationally defined Hg species can be useful in estimating bioavailable Hg to obligatory deposit feeder in tropical mangrove systems.

This is the first study to describe distribution and speciation of Hg in coastal sediments from the central east coast of India. The concentrations of Hg in the studied sediments were found to be much lower than the Hg concentration recommended in coastal sediments by the United State Environmental Protection Agency and the Canadian Council of Ministers of the Environment for the protection of aquatic life. This study suggests that the interactions between Hg and coastal sediments are influenced by particle size (sand, silt and clay) of the sediments and the total organic carbon (TOC) content in the sediments. It was found that the coastal sediments from the central east coast of India could act as a sink for Hg. The availability of strong uncomplexed-Hg binding sites in the coastal sediments was observed.

Interactions of mercury (Hg) with different molecular weight fractions of humic substances (HS) play an important role in controlling distribution, diffusion, speciation, and bioavailability of Hg in natural systems. This study suggests that Hg prefers to associate with higher molecular weight fractions of HS and this association particularly predominates at low pH and high ionic strengths of the medium. The concentrations of aggregated HS (with higher molecular weight) become high at lower pH (acidic condition) and high ionic strength. Molecular weight of HS gradually decreases with the increasing pH (basic condition) and low ionic strength of the medium. The disaggregation property of HS which involves the release of monomers from the surface of the aggregates produces HSs of different intermediate molecular weight with different Hg complexing capacity. Distribution of Hg in different molecular weight fractions of HS is dependent on aggregational and disaggregational properties of HS in aquatic medium. Association of Hg with high molecular weight fraction of HS may alter distribution and bioavailability of Hg in a system as the bioreactivity of organic matter decrease along a continuum of size in aquatic medium.

Mercury (Hg) reduction by humic substances (HS) in the aquatic medium under the dark condition is a poorly understood but important process in Hg biogeochemical cycling. In this study, an effort was made to provide a better understanding of Hg(II) reduction by well-characterized humic substances under dark condition. Reduction of Hg(II) by dissolved HS in aquatic systems increases with increasing Hg loading. However, Hg(II) reduction gradually decreases with the increasing total S content and oxygen containing functional groups in the dissolved HS under dark condition. Increasing major cation concentration decreases the rate of Hg(II) reduction in aquatic systems. High concentration of Ca2+ ion slows down the intermolecular electron transfer from HS to Hg(II) and inhibits the formation of Hg0 in absence of light. This study indicates that complexation of Hg(II) and HS is essential for Hg reduction under dark condition.

The combination of ultrafiltration technique with competing ligand exchange method provides a better understanding of interactions between Ni and different molecular weight fractions of humic acid (HA) at varying pH in aquatic environment. This study suggests that the concentration of aggregated HA (HA with higher molecular weight) becomes high at acidic condition (lower pH) and the molecular weight of HA gradually decreases with the increasing pH. The disaggregation property of HA which involves the release of monomers from the surface of the aggregates produces HAs of different intermediate molecular weights with different Ni complexing capacity. It is observed that Ni prefers to form strong complexes with HAs of lower molecular weight at higher pH and weak complexes with HA of higher molecular weight.

E-Commerce recommender systems are vulnerable to different types of profile-injection attacks where a number of fake user profiles are inserted into the system to influence the recommendations made to the users. In this paper, we have proposed three strategies of detecting such attacks with the help of outlier analysis. In all these strategies, the attack-profiles are considered as outliers in the user rating dataset. Firstly, we have used Partition around Medoid (PAM) clustering algorithm in dete cting the attack-profiles. An incremental version of the PAM algorithm has been applied and tested for evaluating the performance of the system in identifying the attack profiles when they come into the system. Experiments show that though PAM is able to d etect attack profiles with larger number of filler items very well, a percentage of attack profiles with smaller number of filler items is not included in outlier clusters-they are included in large clusters. Secondly, we have applied a PAM-based outlier detection algorithm to find these attack profiles in large clusters. Finally, an angle based outlier detection strategy is used for fin ding attack profiles in the database under attack.

Estuarine and Marine Geology (2011-2015)

Arsenic totals and species were found to vary during a one year period in the surface sediments of Godavari estuary (the third largest river in India). This study suggests that increasing salinity of overlying water column of sediments may alter the mobility of arsenic complexes in an estuarine system. The higher salt (NaCl) concentrations result in less arsenic adsorption to the sediment due to formation of weak arsenic complexes because of competition from Cl − ions or due to a reduction in interparticle attraction by the action of Na + . It is suggested that controlled freshwater discharge (from a dam) in an estuary influences the salinity of surface water and can have significant impact on the distribution and speciation of arsenic in the sediments and water column in such system.

Kinetic and sequential extraction methods were used to investigate chemical speciation and distribution of Co, Ni, and Cu in the estuarine and coastal sediments collected from the central east coast of India. The kinetic (single) extraction study provided a chemically significant description of the kinetics of metals–sediment interactions and correctly predicted the influences of ligand field stabilization energy (LFSE) and water exchange rate (k -w ) on the dissociation rate constants of metals–sediments complexes in the natural systems. The results consistently demonstrate that the fast (k d1 ) and medium fast (k d2 ) dissociation rate constants of the 3 d transition metals complexes in the estuarine and coastal sediments follow the trend as predicted from the LFSEs (weak field) (k d 1,2 ,Co(II) d 7 > k d 1,2 , Ni(II) d 8 > k d 1,2 , Cu(II) d 9 ). However, a higher rate coefficient of water exchange (k -w ) of Cu (II) helps them to form more strong inert complexes than predicted from its LFSE alone. Sequential extraction method was used to fractionate these metals depending upon their association with different phases in the studied sediments. The comparison and statistical analysis of the fractionation data obtained by two independent methods indicate that the transition metals formed strong complexes with the organic matter present in the sediments. However, Cu undergoes strong complexation reaction with organic matter within the sediments followed by Ni and Co. This study suggests that the non-residual fractions (obtained from sequential extraction study) may overestimate the bioavailable fraction of metals in a system.

A simple and sensitive spectrofluorometric method has been developed for the determination of arsenic (As) using rhodamine-B as a fluorescent agent. This method is based on the reaction of As(III) with potassium iodate (KIO3) in acid medium to liberate iodine, which decreases the fluorescence intensity of rhodamine-B. This decrease in intensity was used to quantify As(III). A linear decrease in the response was observed with the increasing As(III) concentrations. An R2 value of 0.995 was obtained. As(III) in the concentration range of 0.4 µg mL−1 to 12.5 µg mL−1 showed linearity and reproducibility by this method. The limit of quantitation was found to be 0.4 µg mL−1 of As(III) was the limit of quantitation. This method was successfully used to determine the total concentration of As in coastal and estuarine sediments. This study suggests that the estuarine sediments were more contaminated with As than the coastal sediments and the probable source of high As content in estuarine sediment is agricultural ...

Chemical speciation of lead (Pb) and cadmium (Cd) in the coastal and estuarine sediments along the central east coast of India was studied by applying sequential and kinetic extraction methods. The results of this study suggest that concentrations of non-residual and dynamic complexes (which are good indicators of bioavailability) of these toxic metals gradually increase with increasing total metal loading in sediments. Increase in bioavailability of these toxic metals with increasing total metals concentrations in the sediments can be a potential threat to benthic organisms and aquatic biota in the system. This study shows that total organic carbon (TOC) is one of the key factors which play a crucial role in controlling speciation of these toxic metals in sediments. However, distribution and speciation of these metals are influenced by their total metal loading and trace metal competitions rather than only TOC content in sediments. An attempt was made to identify the key factors which control speciation of these toxic metals in natural system and provides a better understanding to predict and control pollution of Pb and Cd in coastal and estuarine sediments.

Two independent analytical methods (sequential extraction and kinetic extraction methods) were applied in order to understand the distribution and speciation of La in the coastal and estuarine sediments collected from the central east coast of India. Data obtained from sequential extraction study revealed that La was primarily present as inert complexes (~ 50-60% of the total La) in all the sediments. Amounts of ~ 20-30% of the total La in all the sediments were found to associate with the total organic carbon (TOC) in the sediments. The dissociation rate constants of Lasediment complexes obtained from kinetic extraction studies revealed that the concentration of thermodynamically weak complexes of La gradually increased with the increasing La/ TOC ratio in the sediments. The results of this investigation demonstrate that combination of two analytical methods having complementary analytical capabilities can provide a better physicochemical picture of La speciation than either one of the method can do alone. Combination of the data obtained from sequential extraction and kinetic extraction methods suggest that TOC is one of the key factors in controlling speciation and distribution of La in the sediments.

Context: Scientific assessment of proving symptoms or already recorded symptoms in patients refers to Clinical Verification (CV). There are serious shortcomings of existing methods of CV, mostly arising from qualitative observations made on absolute occurrence of symptoms instead of relative ones. This problem can be resolved by the use of the Likelihood Ratio (LR). Aim: This study aims to estimate the prevalence and LRs of general symptoms of 29 less frequently prescribed homoeopathic medicines. Methods: The study was multicentric, open and observational. Patients were enrolled as per pre-specified eligibility criteria. Alongside, presenting complaints and general symptoms were taken into account during prescription. Medicines were prescribed in centesimal potencies. LR calculation of general symptoms was based on clinician-rated outcomes as 'improved' and 'not improved' of presenting complaints and was divided into three sections: (1) when the prevalence of a symptom was available from literature, LR was calculated by assessing the prevalence of that symptom in the responder sample, (2) in the absence of so, calculation was restricted to mean prevalence data from study sample ('confined LR') and (3) 'confined LRs' were not calculated for symptoms whose prevalence were not recorded for at least five medicines and were kept for estimation in future. Results: Of 166 general symptoms of 29 medicines, LRs and confined LRs >1.5 were elicited for 6 and 49 symptoms, respectively. Conclusion: In spite of considerable caveats, it is the first insight into prevalence and LRs of general symptoms of less frequently prescribed homoeopathic medicines. Further research is warranted.

Kinetic speciation of uranium in model solutions containing uranium and humic acid (HA) and in natural waters has been investigated by Competitive Ligand Exchange Method (CLEM). In alkaline freshwaters, most of uranium species were uranium–carbonate species, which were labile in the CLEM experiment. The uranium speciation of every sample was characterized either as “labile” or “non-labile” uranium complexes depending on the dissociation rate coefficients of the complexes. The results showed that as the U(VI)/HA ratio was decreased, the dissociation rate coefficients decreased and the labile fraction decreased as well. When the U(VI)/HA ratio was 0.1, the labile fraction of the U(VI)-HA increased with increasing pH; however, there was no pH effect on the dissociation of U(VI)-HA complexes at lower U(VI)/HA ratios. Chelex-100 had some limitations in its use for the study of dissociation of U(VI)-HA complex at very low U(VI)/HA ratios. By developing an analytical method and procedure for quantitative determination of kinetic parameters for the dissociation of uranium-HA complexes in model solutions and natural waters, this work has made a substantial contribution to analytical chemistry.

Environmental context. The environmental fate and bioavailability of metal ions in natural waters is determined by their thermodynamic stability and kinetic features, both of which are distributed and depend on the metal ion loading of the system. Diffusive gradients in thin film (DGT) is a dynamic technique for metal speciation analysis that measures a certain portion of these complexes as determined by its operational timescale. Reliable interpretation of data furnished by DGT necessitates characterisation of its features for the particular case of heterogeneous complexes. Abstract. Owing to their inherent heterogeneity, the thermodynamic stability of metal ion complexes with natural ligands is characterised by a distribution, and thus is a function of metal-to-ligand ratio. The kinetic features of such metal complexes are also distributed and can be probed by dynamic speciation techniques. The kinetic regime of the metal complex sample can be manipulated via the metal-to-ligand ratio, and the timescale over which kinetic parameters are actually in effect is defined by the window of the chosen technique. Here we detail the kinetic features of diffusive gradients in thin film (DGT), and show that the range of attainable measurement timescales (τ) is rather limited: variation of the gel layer thickness practically allows only one order of magnitude in τ to be scanned. The more effective use of DGT to probe the distribution of dynamic metal species in heterogeneous systems is via variation of the metal-to-ligand ratio in the sample solution. Compilation of the literature DGT data for natural waters shows that by assuming a Freundlich isotherm relationship, the degree of heterogeneity is reflected in the measured DGT concentration as a function of metal ion loading.

Free metal ion concentration is generally considered a useful indicator of a metal’s bioavailability and ecotoxicity to aquatic biota. This article reports the speciation of nickel in mining and municipal effluents from Sudbury (Ontario, Canada), and also in model solutions containing a fully characterized laurentian fulvic acid (LFA) at environmentally relevant concentrations. A column ion exchange technique (IET) using a cation exchange resin (Dowex 50W-X8) was applied to determine free nickel ion concentrations. In model solutions, reasonable correlation was found between the predictions of an equilibrium-based computer speciation code, Windermere Humic Aqueous Model (WHAM) VI, and the results obtained by IET at low nickel-to-fulvic acid ratios. However at higher mole ratios, the WHAM VI predicted higher free nickel ion concentrations than IET. Only three out of six effluent samples showed reasonable agreement between the IET and the WHAM VI results, indicating the need for further development of IET for application to effluent waters.

This study describes the effect of varying bottom-water oxygen concentration on geochemical fractionation (operational speciation) of Cu and Pb in the underneath sediments across the oxygen minimum zone (Arabian Sea) in the west coast of India. Both, Cu and Pb were redistributed among the different binding phases of the sediments with changing dissolved oxygen level (from oxic to hypoxic and close to suboxic) in the bottom water. The average lability of Cu-sediment complexes gradually decreased (i.e., stability increased) with the decreasing dissolved oxygen concentrations of the bottom water. Decreasing bottom-water oxygen concentration increased Cu association with sedimentary organic matter. However, Pb association with Fe/Mn-oxyhydroxide phases in the sediments gradually decreased with the decreasing dissolved oxygen concentration of the overlying bottom water (due to dissolution of Fe/Mn oxyhydroxide phase). The lability of Pb-sediment complexes increased with the decreasing bottom-water oxygen concentration. This study suggests that bottom-water oxygen concentration is one of the key factors governing stability and lability of Cu and Pb complexes in the underneath sediment. Sedimentary organic matter and Fe/Mn oxyhydroxide binding phases were the major hosting phases for Cu and Pb respectively in the study area. Increasing lability of Pb-complexes in bottom sediments may lead to positive benthic fluxes of Pb at low oxygen environment.

Total Hg distributions and its speciation were determined in two sediment cores collected from the western continental marginal high of India. Total Hg content in the sediment was found to gradually increase (by approximately two times) towards the surface in both the cores. It was found that Hg was preferentially bound to sulfide under anoxic condition. However, redox-mediated reactions in the upper part of the core influenced the total Hg content in the sediment cores. This study suggests that probable increase in authigenic and allogenic Hg deposition attributed to the increasing Hg concentration in the surface sediment in the study area.