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Author(s): Jadhav, Harshal; Fulke, A.B.; Dasari, L.N.; Dalai, A.; Haridevi, C.K.
Source: Bioresource Technology, vol.391, Pt.A; 2024; Article no: 129952
Impact Factor: 11.400
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9164
Abstract: Bio-mitigation of plastics by microorganisms generates carbon dioxide (CO2) that can be utilized for algal biomass generation. Pseudomonas mendocina ABF786, reportedly the most efficient plastic-degrading bacteria, was screened using the modified most probable number technique. This study highlights the use of an integrative prototype for the production of microalgal biomass (Chlorella vulgaris) in combination with bio-mitigation of plastics, which serves a dual purpose: (i) increased plastic-degradation capability by microorganisms (53%-85% increase in plastic weight loss) due to removal of CO2 feedback inhibition and (ii) increased algal biomass generation (200%-237%) due to supply of extra CO2 from plastic degradation to the algal cultivation flask. Whole-genome sequencing and functional annotation confirmed that all the genes involved in the mineralization of plastic to CO2 are present within the genome of P. mendocina ABF786. Using two or more microbial cultures for remediation may increase the process efficiency.
Microplastics in the sediments along the eastern Arabian Sea shelf: Distribution, governing factors and risk assessment
Author(s): Gupta, Priyansha; Saha, M.; Suneel, V.; Rathore, Chayanika; Chndrasekhararao, A.V.; Gupta, G.V.M.; Junaid, C.K.
Source: Science of The Total Environment, vol.910; 2024; Article no: 168629
Impact Factor: 9.800
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9165
Abstract: Despite the omnipresence of microplastics (MPs), the studies around the western continental shelf of Indian Ocean (Eastern Arabian Sea-EAS) are uncovered and understudied. Thus, the present study was focused to understand the spatial distribution, characterization and risk assessment of MPs in sediment across seven coastal transects (10 to 50 m) all along the EAS shelf. The highest MPs concentration (MPs/kg d.w.) was detected in the northern EAS (NEAS; 2260 1050) followed by central (CEAS; 1550 1012) and southern (SEAS; 1300 513) shelves. Among all distinct locations, the highest concentration of MPs (2500 1042) was detected in the north coastal sediments off Mumbai, followed by off Mangalore (1480 1169) in the center and off Kochi (1350 212) in the south. MPs were found in the form of fibres, fragments and films with a predominance of fibres (~7080 %). Approximately 74.6 % of the total MPs were in the size range of 300 m to 5 mm. The surface of detected MPs was rough, irregular, and mechanical weathering features such as pits, grooves also observed and spotted with bacterial community structures. Polypropylene (PP; 34 %), polyisoprene (PIP; 19 %), butyl rubber (18 %), and low-density polyethylene (LDPE; 13 %) were dominant polymers. The pollution load index highlighted minor risk while the polymer hazard index exhibited a hazard level of V. Litter discharge, fishing activities, and active marine navigation are among the many high-risk sources of plastic contamination in this region. Due to the prevailing winds, currents, low sea surface height, and high precipitation, the conditions in the EAS are favorable for the accumulation of both sea-based and land-based particles. Hence, this study provides novel insights into the potential risks posed by MP to the IO rim and associated marine ecosystem which will enhance our knowledge of the ecological implications and consequences of MP pollution, ultimately aiding in developing effective management and mitigation strategies
Environmental variables and its association with faecal coliform at Madh Island beaches of megacity Mumbai, India
Author(s): Fulke, A.B.; Panigrahi, J.; Eranezhath, S.; Karthi, J.; Dora, G.U.
Source: Environmental Pollution, vol.341; 2024; Article no: 122885
Impact Factor: 8.900
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9168
Abstract: The abundance of fecal-indicating bacteria in water bodies are said to be influenced by environmental conditions. The effect of environmental parameters on the changing microbial population plays an important role in coastal water quality assessment. It's crucial to comprehend these patterns in order to support management initiatives for pollution control. There are studies on faecal bacteria contamination of surface water and how environmental conditions affect it, however majority of them are based on large river basins and temperate regions of developed countries. In this paper, we study the different physicochemical and physical factors of the five recreational beaches in Mumbai, India and examine how these environmental factors affect the levels of faecal indicating bacteria, namely, coliforms in the region. A relatively high number of coliform was identified from the water and sediment samples of Marve Beach (>1600 MP N/100 ml or g), followed by Erangal Beach and Danapani Beach (150350 MP N/100 ml or g), exceeding the normal standard limits of <100 MP N/100 ml set by the Central Pollution Control Board (CPCB) of India. Of the physiochemical parameters examined, BOD showed to have a strong positive correlation with the coliform bacteria. The nutrients and heavy metal concentrations did not show any major effect on the microbial population. The MIKE CMAP predicted tide, MIKE3 Flow Model FM simulated coastal current, ERA5 hourly wind, as well as SWAN model simulated nearshore wave together considerably exhibit alliance of microbial behavior in the beaches with ambient physical processes. This study reveals that Mumbai's coastal water contain significant concentrations of faecal bacteria, which, if not monitored regularly could have future consequences on the recreational activities of the region, thereby on public health. This assessment might help in simulation of water quality prediction, and for optimizing the coastal zone management and development across recreational beaches.
Trait-based classification and environmental drivers of phytoplankton functional structure from anthropogenically altered tropical creek, Thane Creek India
Author(s): Hardikar, R.; Haridevi, C.K.; Deshbhratar, S.
Source: Marine Pollution Bulletin, vol.198; 2024; Article no: 115767
Impact Factor: 5.800
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9163
Abstract: The present study on variability in phytoplankton functional structure through a trait-based approach described the species-trait-environmental relationship and its possible impact on ecosystem functioning. Based on trait similarities 102 phytoplankton species were clubbed into 14 distinct functional groups. Among others, FGs-XI and XII (small size, chain-forming species with medium to high SA:V ratio and space between cells in chain) were the most dominant due to their competitive advantage in resource utilization and avoidance of loss processes. The morphological traits space between cells and cellular protrusion along with temperature and ammonia played a decisive role in their seasonal succession. Eutrophication in Thane Creek favors the dominance of anti-grazing traits which increases the phytoplankton biomass through efficient resource acquisition but can encumber the energy transfer efficiency. The dominance of HAB species impedes ecosystem functioning which raises public health concerns. The strong correlation of environmental variables with phytoplankton functional structure reinforces the practical implementation of a trait-based approach for understanding phytoplankton community dynamics under varying environmental conditions.
Toxigenic Escherichia coli with high antibiotic resistance index recovered from sands of recreational beaches of Mumbai, India
Author(s): Maloo, A.; Fulke, A.B.; Sukumaran, S.
Source: Marine Pollution Bulletin, vol.198; 2024; Article no: 115837
Impact Factor: 5.800
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9162
Abstract: Mumbai, India's seven-island city, is known for its sandy beaches as a major tourist attraction, but urbanization and industrialization have weakened the environment. Unregulated sewage disposal and untreated effluents off the coast have made the beach environment vulnerable. Therefore, monitoring water and sand quality at beaches should be mandatory. This study was thus designed to determine the microbiological status of selected sandy beaches, viz. Versova, Juhu, and Girgaon. The study found fecal coliforms in the sand, with stx1 and stx2 genes specific for Shiga toxin-producing E. coli pathotypes in 5.5 % of isolates, whereas the presence of eaeA gene specific for enteropathogenic E. coli pathotype was detected in 12.2 % of isolates, and the presence of the LT and ST genes specific for enterotoxigenic E. coli pathotype was detected in 6.6 % of isolates. Multiple antibiotic-resistant indices indicated high-risk contamination sources. The study suggests routine monitoring of pollution levels at coastal cities' beaches.
Land subsidence studies in the Godavari Delta regions of the East coast of India using ALOS and Sentinel 1 data
Author(s): ManiMurali, R.; Reshma, K.N.; SanthoshKumar, S.; Agrawal, Ritesh; Ratheesh, Ramakrishnan; Sreejith, K.M.; Rajawat, A.S.
Source: Ecological Informatics, vol.78; 2023; Article no: 102373
Impact Factor: 5.100
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9155
Abstract: Subsidence in coastal deltas is a challenging issue globally, influenced by both climate and anthropogenic pressures. Owing to its rich economic value, the Godavari Delta on the east coast of India attracts the human population and is therefore a hub of developmental activities. We quantified the line of sight (LOS) rate of land deformation in the Godavari Delta, India, for two different periods using the time series interferometric analysis of Advanced Land Observing Satellite Phase Arrayed L-band Synthetic Aperture Radar (ALOS PALSAR) (20072011) and C-band Sentinel-1A (20172020) datasets. This approach was based on the Small Baseline Subset (SBAS) algorithm, which constructed 76 (ALOS) and 333 (Sentinel-1A) pairs of interferograms. The results indicated that the majority of deltas had varying LOS deformation rates in both periods. The southern and northern coastline of the deltas showed subsidence (-10 to -20 mm/yr) and uplift (5 mm to 7 mm/yr), respectively, from 2007 to 2011. The uplift (11 mm/yr) during 20172020 was attributed to coastal erosion and accretion during the study period. Statistical analyses showed that the majority of the coastline experienced erosion from 2006 to 2011, ranging from 0 30 m/yr. Conversely, during 20172019, accretion ranging from 0-30 m/yr was dominant. The Kakinada spit has recently experienced an uplift of 8 mm/yr. Many factors contributing to deformation, such as groundwater fluctuations, rainfall, land use and land cover (LULC) changes, and water quality, were explored. Groundwater level variations were strongly correlated with the rate of deformation. A direct relationship was also observed between water recharge through rainfall and the ground deformation rate. The subsidence rate was estimated as 0 to 8 mm/yr from 2007-2011 and -10 to -20 mm/yr for 20172020 in the Godavari Delta. Increased urban areas and land conversion from the LULC analysis were the causative factors of subsidence in this region. Thus, the Godavari Delta will become highly vulnerable, as the region has shown various LOS deformation rates. Studies on land subsidence are highly relevant for effective coastal management planning and management
High waves measured during tropical cyclones in the coastal waters of India
Author(s): SanilKumar, V.; Anusree, A.
Source: Ocean Engineering, vol.289 (Pt.1); 2023; Article no: 116124
Impact Factor: 5.000
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9157
Abstract: The high waves in the ocean generated by tropical cyclones cause ship accidents and damage to offshore structures. This study examines the characteristics of high waves from the measured half-hourly directional wave data using waverider buoys during five cyclones in the coastal waters of India at 15-50 m water depth. The highest wave height measured in different cyclones varied from 8.1 to 13.5 m. At all locations, the influence of the cyclone on wave heights lasted for a short period only (3 days). The average increase in wave height with time due to the influence of cyclones is ~0.17 m/h. The maximum crest height and the maximum height of the extreme waves are 0.90 and 1.75 times the significant wave height, respectively. When the cyclone reaches its peak intensity, the highest significant wave heights associated with Phailin and Kyarr are found to be in the right front and right back quadrants relative to the cyclone heading, whereas, for Thane, Hudhud and Tauktae, they are located in the right back quadrant. The significant wave height obtained from the time series is smaller than that obtained from the corresponding wave spectrum.
On the simulations of latent heat flux over the Indian Ocean in CMIP6 models
Author(s): Soumya, M.; Ruchith, R.D.
Source: Climate Dynamics, vol.61(11-12); 2023; 5573-5595
Impact Factor: 4.600
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9148
Abstract: The historical simulations of latent heat flux (LHF) over the Indian Ocean (IO) region in 46 climate models participating in the phase 6 of Coupled Model Intercomparison Project (CMIP6) have been evaluated against the ERA5 dataset for the period 19752014. The multimodel mean (MMM) captures the observed spatial pattern of LHF climatological mean state to a great extent, but there are large biases in magnitude, especially over the region north of 20S and south of 40S, and these biases are common to more than 70% of the individual CMIP6 models. The origins of these biases are due to overestimated surface winds and vertical humidity gradients in the models. The simulated trend values of LHF are largely underestimated and are highly inconsistent in individual models. The basin-wide increase of surface saturation specific humidity (Qs) is largely compensated by a similar increase in near-surface saturation specific humidity (Qa) trend, which leads to reduced vertical humidity gradient for the latent heat transfer to take place at the air-sea interface. The long-term trend of sea surface temperature (SST) and Qs are found to be reasonable in CMIP6 models. One of the reasons for the underestimated LHF trend in CMIP6 models is the faster rate of increase of Qa and very slow rate of increase of surface wind speed compared to the ERA5 dataset.
Hydrothermal amorphous silica, barite and orpiment from the crater area of seamount (SM-13) off Nicobar island, Andaman sea: Indications for the development of a new hydrothermal field
Author(s): Peketi, A.; Sriram, G.; Mazumdar, A.; Dewangan, P.; Zatale, Anjali; Rajurkar, V.; Shirodkar, G.; Mahale, V.; Yatheesh, V.
Source: Marine and Petroleum Geology, vol.160; 2024; Article no: 106606
Impact Factor: 4.200
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9167
Abstract: The Andaman sea characterized by trench-arc-backarc elements (Andaman-Nicobar island-arc, the Andaman back-arc spreading center, the seamount complex, and the back-arc basin) is a complex active basin and is known for hydrothermal activity in some of the seamounts (subaerial and submarine) of the volcanic arc. In the present study, 13 submarine seamounts (SM1- SM13) in the southern Andaman volcanic arc, extending from 647N: 9443E to 7 56 N: 94 2.47E, were surveyed onboard RV Sindhu Sadhana (November 2021) to find the evidences for the hydrothermal activity. Out of the 13 seamounts, at one crater seamount (SM-13) we have observed evidence for hydrothermal activity characterized by plumes rich in dissolved gases (mainly CO2) in the water column, live chemosymbiotic organisms (Bathymodiolus species), and neoforming minerals such as amorphous silica, barite and orpiment. We observed two plumes rich in dissolved gases (mainly CO2), called GP1 and GP2, in the water column at two different water depths i.e. 400 and 380 mbsl respectively. Geochemical analysis of the water samples shows enhanced TCO2 concentrations within the plumes rich in dissolved gases (mainly CO2) observed in sub-bottom profiler data, however, the dissolved methane concentrations do not show any enrichment when compared with ambient seawater concentrations. Apart from the enhancement in the TCO2 concentrations, pH and total alkalinity data also show fluctuations within the same depth zone which may be attributed to the hydrothermal plume exhausting from the crater seamount. The occurrence of live chemosymbiotic organism Bathymodiolus species indicate an active and continuous supply of H2S. The precipitation of neoforming hydrothermal minerals such as amorphous silica, tabular barite, and orpiment on the surface of the rock samples further supports the hydrothermal activity. Previous studies carried out in 2007 have reported hydrothermal ferromanganese oxides precipitated from low-temperature hydrothermal fluids (Surya prakash et al., 2012) and inferred SM-13 as a dormant submarine volcano (Kamesh Raju et al., 2012). However, after 14 years, we observe volatile emissions to the water column, hydrothermal mineral precipitation and live chemosymbiotic organisms from the same seamount. These observations of the present study infer development of a new hydrothermal field in the least explored Andaman Sea. This study adds up a new active site to the global hydrothermal inventory which may allow better estimation of global hydrothermal flux and its role in oceanic elemental cycle
Variation of amino acid in the sinking particulates in the northeastern Arabian Sea and the northern Bay of Bengal
Author(s): Apsara, P.V.; Kurian, S.; Joseph, D.; Megha, D.; Kankonkar, H.; Khandeparker, R.; Karapurkar, S.; Methar, A.
Source: Progress in Oceanography, vol.219; 2023; Article no: 103168
Impact Factor: 4.100
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9160
Abstract: Sediment traps are widely used to get insight into how particulate matter forms and settles in the water column. Earlier studies in the Northern Indian Ocean have shown that the sinking flux depends mainly on surface primary production and varies seasonally and inter-annually. In the case of the Bay of Bengal, river runoff plays a significant role in the sinking flux. As a part of the SIBER-INDIA program, a mooring consisting of sediment traps was deployed at three depths (495 m, 1205 m, and 2915 m) in the Arabian Sea (Northeastern Arabian Sea sediment trap, NEAST; 16.87N, 67.77E) and at 580 m, 1110 m, and 1635 m in the Bay of Bengal (Bay of Bengal sediment trap, BoBST; 18.21N, 89.63E). We present here data on total fluxes, concentrations of particulate carbon and nitrogen, biogenic opal, and amino acid composition for the period 20172018 in both basins. Particle flux in the Arabian Sea was influenced by monsoon-related processes with higher flux during the northeast monsoon (NEM) and southwest monsoon (SWM) seasons, whereas the flux was higher in BoB during SWM. Particulate nitrogen (PN), particulate organic carbon (POC), and total hydrolysable amino acid (THAA) mostly decreased with depth in all traps due to the decomposition of labile organic constituents in the sinking flux. Changes in the decomposition of organic matter with depth were further reflected in the POC/PN molar ratios, which increased with depth in the Arabian Sea. A low POC/PN molar ratio associated with the higher THAA concentration in most of the shallow traps indicates the presence of fresher organic matter. Among the THAA, Glycine (Gly) was the dominant amino acid in all the samples followed by Aspartic acid (Asp), Glutamic acid (Glu), Serine (Ser), and Alanine (Ala). The amino acid-based degradation index (DI) reveals the degradation of labile organic matter with depth in the NEAST. However, the middle trap in the BoB showed a different trend with higher total and lithogenic fluxes, POC, PN, and DI values compared to the shallow trap indicating lateral advection in the bay. Monsoonal changes and mesoscale eddies make these basins distinct from one another and influence their sinking fluxes and biogeochemical settings.
Latent heat flux variability over the tropical Indian Ocean
Author(s): Soumya, M.; Ruchith, R.D.; Rahul, S.; Shanas, P.R.
Source: International Journal of Climatology, vol.43(13); 2023; 6225-6242
Impact Factor: 3.900
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9150
Abstract: The seasonal evolution and interannual variability of latent heat flux (LHF) over the tropical Indian Ocean (TIO) region is examined for the period 19802019. The seasonal distribution of LHF is dominated by the winter pattern of each hemisphere in the TIO. Climatologically high LHF is mostly confined to the Arabian Sea and Bay of Bengal regions in the north Indian Ocean and the zonal belt between 10oS and 25oS in the south Indian Ocean. Warm and cold phases of El-Nio Southern Oscillation, Indian Ocean Dipole (IOD), and their co-occurrence events leave distinct LHF signatures over the TIO. The LHF anomalies during these events are more profound than pure events with enhanced latent heat loss when the La Nia and negative IOD events coincide. The LHF anomalies associated with the wind-evaporation-SST feedback is prominent when positive IOD co-occur with the El-Nio event. Both the vertical humidity gradient and wind speed changes play substantial roles in driving LHF anomalies during the co-occurring events of NIOD and La Nia
Control of source-to-sink processes on the dispersal, fractionation, and deposition of magnetic minerals in a tropical mesotidal estuarine system
Author(s): Badesab, F.K.; Kadam, N.; Gullapalli, S.; Dewangan, P.; Gaikwad, V.; Satelkar, N.P.; Khalap, S.; Venkateshwarlu, M.; Sahoo, R.K.; Fernandes, Walsh; Dahake, P.; Banerjee, Deblina
Source: Geochemistry, Geophysics, Geosystems, vol.24(11); 2023; Article no: e2023GC011178
Impact Factor: 3.500
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9152
Abstract: This study aims to elucidate the control of source-to-sink processes on the sediment dynamics of a complex mesotidal tropical estuarine system using rock magnetic, sedimentological, mineralogical, and geochemical methods. Integration of multiproxy data of catchment rocks, riverbank and hinterland soils, and bedload sediments from various depositional environment of Mandovi estuary revealed a marked change in the magnetic mineral composition and accumulation pattern. The magnetic mineralogy mainly comprised ferri- (magnetite, titanomagnetite) and antiferromagnetic (hematite, goethite) minerals. Higher accumulation of coarser magnetic particles in the catchment area followed by a systematic trend of progressive fining of magnetic grain size in the down reaches of the estuary can be attributed to the decrease in transport energy. Enhanced accumulation of coarser magnetic particles in the estuarine region can be reconciled with the strong tidal and wave-induced bottom currents, which preferentially favored mineral-density selective fractionation resulting in higher deposition of heavy (magnetic) particles. A clear trend of loss of fluvial-derived fine silt-size clastic sediments and selective retention of coarser and heavy magnetic particles within the estuary can be attributed to the hydrodynamic driven sediment partitioning regime, which inhibited the permanent settling of fine sediment fraction and are therefore frequently flushed out to the sea. A marked drop in S-ratio in different zones of the estuary can be linked to the increased input of high coercive magnetic particles derived from pedogenic soils along eroding riverbanks. We further demonstrate that the S-ratio is an effective parameter to track the riverbank erosion in an estuarine system.
Dynamics of nitrous oxide and methane in the southeastern Arabian Sea
Author(s): Arya, K.S.; Gireeshkumar, T.R.; Vignesh, E.R.; Muraleedharan, K.R.; Jaleel, A.K.U.; Razaque, Abdul M.A.; Furtado, C.M.; Sudheesh, V.; Nair, T.M.B.; Krishnamohan, K.S.
Source: Marine Chemistry, vol.258; 2024; Article no: 104333
Impact Factor: 3.000
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9166
Abstract: This study examined the factors controlling the intra- and inter-seasonal variations of dissolved methane (CH4) and nitrous oxide (N2O) in the southeastern Arabian Sea (SEAS). Time-series measurements of CH4, N2O and allied biogeochemical parameters were carried out during the monthly campaigns in the coastal waters and a seasonal campaign in the shelf waters of the SEAS. The southwest monsoon period (SWM) brought drastic changes in the regional hydrography through the incursion of hypoxic waters due to coastal upwelling, which increased N2O concentrations substantially but reduced CH4 levels. The ranges of N2O and CH4 during the upwelling period were 889 nM and 9165 nM, respectively, and the non-upwelling period was 227 nM and 5271 nM, respectively. The significant positive correlations of N2O with apparent oxygen utilisation (AOU), the sum of dissolved nitrate and nitrite (NO2 + NO3) and excess N2O (N2O), as well as a negative correlation with dissolved oxygen indicates that nitrification is the major process in this region during the non-upwelling period. In contrast, during SWM, N2O did not correlate with NO2 + NO3; however, it exhibited a significant negative correlation with dissolved nitrite (under hypoxia), suggesting the possibility of nitrifier-denitrification as an active process during hypoxia. The high (low) levels of CH4 recorded during the oxic spring inter-monsoon (hypoxic during the SWM) period showed a direct dependency on the changes in the benthic community. The high abundance of the adult macrofauna and active bioturbation resulted in high sedimentary CH4 release, which led to enhanced water column CH4 concentrations (17271 nM) during the spring inter-monsoon period. In addition, the breakdown of methylated organic compounds under nutrient-limited conditions may also support the elevated CH4 levels in surface waters. A low macrofaunal abundance and reduced bioturbation led to a considerable reduction of subsurface CH4 concentrations during hypoxia. Overall, the SEAS is found to be a net source of CH4 and N2O to the atmosphere, with its sea-to-air fluxes ranging from 1.7 to 85.8 M m2 d1 (19.88 22.20 M m2 d1) for N2O and 4756 M m2 d1(133 158 M m2 d1) for CH4.
Efficacy of amorphous TiOx-coated surfaces against micro- and macrofouling through laboratory microcosms and field studies
Author(s): Khandeparker, L.; Desai, D.V.; Mittireddi, R.T.; Panda, Emila; Hede, N.; Mapari, K.
Source: Biofouling: The Journal of Bioadhesion and Biofilm Research, vol.39(8); 2023; 853-866
Impact Factor: 2.700
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9154
Abstract: In this study, Soda Lime Glass (SLG) and Stainless Steel (SS316L) substrata coated with Titanium oxide (TiOx) were tested for their efficacy in the laboratory microcosms and in field against micro- and macrofouling. Laboratory microcosm studies were conducted for five days using natural biofilms, single-species diatom (Navicula sp.), and bacterial biofilms, whereas field observations were conducted for 30days. The TiOx-coating induced change in the mean contact angle of the substratum and rendered SS316L more hydrophilic and SLG hydrophobic, which influenced the Navicula sp. biofilm, and bacterial community structure of the biofilm. Overall, the TiOx-coated SS316L showed minimal microfouling, whereas non-coated SLG exhibited greater efficacy in deterring/preventing macrofouling organisms. Moreover, the reduction in macrofouling could be attributed to high abundance of Actinobacteria. Unraveling the mechanism of action needs future studies emphasizing biochemical processes and pathways
Ocean surface wave dynamics off the southern tip of Indian mainland
Author(s): SanilKumar, V.; Sivakrishnan, K.K.
Source: Dynamics of Atmospheres and Oceans, vol.104; 2023; Article no: 101411
Impact Factor: 1.700
NIO Repository: https://drs.nio.res.in/drs/handle/2264/9161
Abstract: Waves collected in the nearshore waters off the southern tip of the Indian mainland from February 2018 to January 2019 are used to examine the wave spectral characterization. The annual mean of the significant wave height (1.23 m) in this area is slightly higher than that along the waters of the eastern Arabian Sea (0.9-1.1 m), but the maximum value in an annual cycle (3.6 m) is less than that (4.5-5 m) found in those regions. Compared to other coastal locations around India, significant seasonal variations are not observed in the wave height at this location. A maximum of four wave systems are present in the study region. 76% of the surface height variance in the region results from swells from the south-southwest, and the balance is wind-seas from the west to the southeast. In a year, 72% of the time, single peak spectra are observed, majority of them are swell-dominated. The annual mean peak period and the wave energy potential of the area are larger than that available in the rest of the locations around the mainland of India. Also, the area is not subjected to high waves. Hence, it is an ideal location for installing wave energy converters.