Modeling the underwater light field fluctuations in coastal oceanic waters: Validation with experimental data     

Balasubramanian Sundarabalan  Palanisamy Shanmugam  Yu-Hwan Ahn 《Ocean Science Journal》2016,51(1):67-86

Modeling of the wave-induced underwater light fluctuations at near-surface depths in coastal oceanic waters is challenging because of the surface roughness and strong anisotropic effects of the light field. In the present work, a simple and computationally efficient radiative transfer model is used for the wind-driven sea surface for simulating underwater light fields such as downwelling irradiance (E_d), upwelling irradiance (E_u), and upwelling radiance (L_u) in a spatial domain. It is an extension of our previous work that essentially combines the air–sea interface of the wind-driven sea surface with transmittance and reflectance along with the diffuse and direct components of the homogenous and inhomogeneous water column. The present model simulates underwater light fields for any possible values of absorption and backscattering coefficients. To assess the performance of the model, the E_d, E_u, and L_u profiles predicted by the model are compared with experimental data from relatively clear and turbid coastal waters. Statistical results show significantly low mean relative differences regardless of the wavelength. Comparison of the simulated and in-situ time series data measured over rough sea surfaces demonstrates that model-observation agreement is good for the present model. The Hydrolight model when implemented with the modified bottom reflectance and phase function provides significantly better results than the original Hydrolight model without consideration of the bottom slope and vertically varying phase function. However, these results are non-spatial and have errors fluctuating at different wavelengths. To further demonstrate the efficiency of the present model, spatial distribution patterns of the underwater light fields are simulated based on the measured data from a coastal station for different solar zenith angles (under sunny condition). Simulated wave-induced fluctuations of the underwater lights fields show a good consistency with in-situ data for a few near-surface depths. The present model also provides a reasonable approximation for simulating wave-induced effects on the downward irradiance field and its anisotropic conditions caused by the surface roughness, wavelength and angle of incidence.  相似文献   

Mine Burial in the Shoaling Zone: Scaling of Laboratory Results to Oceanic Situations     

Testik  F.Y. Voropayev  S.I. Fernando  H.J.S. Balasubramanian  S. 《Oceanic Engineering, IEEE Journal of》2007,32(1):204-213

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Geochemical and statistical approach for evaluation of heavy metal pollution in core sediments in southeast coast of India   总被引：6，自引：2，他引：4  

B. R. R. Seshan M.Phil.  U. Natesan Ph.D.  K. Deepthi M.Sc. 《International Journal of Environmental Science and Technology》2010,7(2):291-306

Industrialization coupled with urbanizaton has led to stress in the Buckingham Canal which runs parallel to Bay of Bengal at a distance of around 1 km from the coastline. 4 sediment cores were collected along Ennore — Pulicat stretch to determine acid leachable trace metal concentration. Core samples were collected using gravity corer. The cores were sliced horizontally at 2.5 cm to determine the grain size, sediment composition, pH, organic matter, calcium carbonate, acid leachable trace metals; cadmium, chromium, copper, lead, zinc. The trace metals were extracted using acid mixture containing hydro fluoric acid, nitric acid and sulphuric acid and analysed by atomic emission spectrophotometer. In an attempt to infer anthropogenic input from geogenic input, several approaches including comparison with sediment quality guidelines — ecotoxicological sense of heavy metal contamination and classification by quantitative indexes such as geoaccumalation index, anthropogenic factor, enrichment factor, contamination factor and degree and pollution load index was attempted. Grain size analysis and sediment composition of core samples shows Ennore is sandy in nature having a neutral pH. Organic matter enrichment is observed to a higher extent in core 3. Core 2 at a depth of 5 cm shows organic matter of 9.4 %. calcium carbonate is totally absent at the surface sediments in core 2. Cores collected within the canal showed a higher heavy metal concentration than the cores collected from Pulicat lagoon and 2 km into the Ennore Sea. The trace metal concentration for cadmium, lead and zinc in Ennore does not pose a threat to the sediment dwelling fauna whereas chromium and copper are likely to pose a threat. Quantitative indexes place Ennore under moderately polluted. Ennore is likely to face a serious threat of metal pollution with the present deposition rates unless stringent pollution control norms are adopted.  相似文献   

Environmental aspects in Dalli-Rajhara iron ore mine area,M.P. using digital image processing techniques     

A Jeyaram  R Balasubramanian  Y Vxxx N Krishna Murthy  R L Karale  Balbhir Singh 《Journal of the Indian Society of Remote Sensing》1993,21(3):167-177

Landsat MSS (1982) and IRS LISS-II (1989) data have been used to study the land use/land cover changes in Dalli-Rajhara iron ore mine area. Supervised classification has been performed on the temporal data to generate land use/land cover maps. Land use/land cover categories generated from IRS LISS-II data of 36 m resolution has been resampled to 80 m and areal statistics have been computed for 2, 4, 8 and 10 km wide strips around Dalli-Rajhara iron ore mine. The environmental impact due to on-going mining activities in the area has been analysed. The results of this study indicate that due to increase in mine-related and agricultural activities, forests have been degraded and also forest areas have been reduced considerably.  相似文献   

Application of Landsat and aerial data for evaluating the hydrogeologic conditions of Pambar River Sub-Basin,Tamil Nadu     

P. Radhakrishnamoorthy  A. Perumal  T. Balasubramanian 《Journal of the Indian Society of Remote Sensing》1983,11(2):39-45

Landsat Falsle-Colour composites of 250,000 scale were used for evaluating the hydrogeologic conditions of Pambar River Sub-Basin. The region studied is comprised of crystalline metamorphic rocks. Oval features and Lineaments suspected to be the potential zones for ground water exploration were mapped from Landsat images. These areas were studied in detail using aerial photographs of 1:60,000 scale followed by field checks. Integrating the geology, geomorphology, landuse and geophysical data a final hydrogeologic conditions of the area was evaluated. The study indicates that the oval features mapped from Landsat images are the structural basins. Though many wells are located on the linear features, the yields of the wells are low due to mineralization. Against the general view that the sturcltural basins will have good ground water potential, it is interesting to note that the basins located within Pambar River Sub-Basin does not show good potential possibilities. The favourable geomorphic units such as buried channels, buried pediments, etc., are the only potential reservoirs available in this area.  相似文献   

International Emission Trading and the Cost of Greenhouse Gas Emissions Mitigation and Sequestration   总被引：1，自引：0，他引：1  

Michael J. Scott  James A. Edmonds  Natesan Mahasenan  Joseph M. Roop  Anthony L. Brunello  Erik F. Haites 《Climatic change》2004,64(3):257-287

The deployment of carbon capture and sequestration (CC&S) technologies is greatly affected by the marginal cost of controlling carbon emissions (also the value of carbon, when emissions permits are traded). Both the severity and timing of emissions limitations and the degree to which emissions limitation obligations can be traded will affect the value of carbon and thereby the timing and magnitude of CC&S technology deployment. Emissions limits that are more stringent in the near term imply higher near-term carbon values and therefore encourage the local development and deployment of CC&S technologies.Trade in emissions obligations lowers the cost of meeting any regional or global emissions limit and so affects the rate of penetration of CC&S technologies. Trade lowers the marginal value of carbon and CC&S penetration in high cost regions and raises the marginal value of carbon and CC&S penetration in low cost regions. The net impact on the world CC&Stechnologies depends on whether their increased use in low-cost regions exceeds the reduced use in high-cost regions.In the long term, CC&S technologies must not only remove carbon but permanently sequester it. If reservoirs are not permanent, then the emissions and costs of control are merely displaced into the future. The paper presents quantitative estimates for the impacts of trade in emissions limitation obligations on the timing, magnitude, and geographic distribution of CC&S technologies and the marginal and total costs of carbon control.  相似文献   

Impact of sealevel rise along Goromandal coast using GIS     

Usha Natesan 《Journal of the Indian Society of Remote Sensing》2005,33(1):69-73

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ANN application for prediction of atmospheric nitrogen deposition to aquatic ecosystems   总被引：1，自引：0，他引：1  

Palani S  Tkalich P  Balasubramanian R  Palanichamy J 《Marine pollution bulletin》2011,62(6):1198-1206

The occurrences of increased atmospheric nitrogen deposition (ADN) in Southeast Asia during smoke haze episodes have undesired consequences on receiving aquatic ecosystems. A successful prediction of episodic ADN will allow a quantitative understanding of its possible impacts. In this study, an artificial neural network (ANN) model is used to estimate atmospheric deposition of total nitrogen (TN) and organic nitrogen (ON) concentrations to coastal aquatic ecosystems. The selected model input variables were nitrogen species from atmospheric deposition, Total Suspended Particulates, Pollutant Standards Index and meteorological parameters. ANN models predictions were also compared with multiple linear regression model having the same inputs and output. ANN model performance was found relatively more accurate in its predictions and adequate even for high-concentration events with acceptable minimum error. The developed ANN model can be used as a forecasting tool to complement the current TN and ON analysis within the atmospheric deposition-monitoring program in the region.  相似文献   

Breeding and mass scale rearing of clownfish Amphiprion percula: feeding and rearing in brackishwater     

DHANEESH Kottila Veettil  AJITH KUMAR Thipramalai Thankappan  SWAGAT Ghosh  BALASUBRAMANIAN Thangavel 《中国海洋湖沼学报》2012,30(4):528-534

Breeding and mass scale larval rearing of clownfish Amphiprion percula is very limited in brackishwater. We designed an indoor program of A. percula culture in brackishwater with a salinity of 24±1, during which the impacts of feed type, water temperature, and light intensity, on the efficiency of its reproduction, were revealed. The fish were accommodated along with sea anemones in fibre glass tanks to determine the influence of brooder diet on breeding efficiency. Higher reproductive efficiency [number of eggs laid (276 22.3 eggs)] was observed when fish were fed live Acetes sp. rather than clam (204 16.4 eggs), trash fish (155 12 eggs) and formulated feed (110 10 eggs). The spawning rate was increased during September and October (water temperature, 28.74 0.55°C) on average of 2.4 spawning per month; and low spawning rate was in January (water temperature, 24.55 0.45°C) on average of 1 spawning per month. Among three light intensities (100, 500, and 900 lx) set to evaluate larval survival rate, larvae showed the highest survival rate (65.5%) at 900 lx. The breeding method specifically in brackishwater developed in the present study is a new approach, will help the people from the regions of estuary and backwater to enhance their livelihood and it will lead to reduce the exploitation from the wild habitat.  相似文献   

Influence of enzymatic lime on clay mineral behavior     

Greeshma Nizy Eujine  Sreedharan Chandrakaran  Natesan Sankar 《Arabian Journal of Geosciences》2017,10(20):454

Atterberg Limit Tests, unconfined compressive strength tests, and California Bearing Ratio Tests were conducted on the two minerals—kaolinite and bentonite—after subjecting them to stabilization with lime, enzyme, and enzymatic lime. The purpose of the study was to evaluate the effectiveness of enzymatic lime as a stabilizer over lime and enzyme. Results establish that enzymatic lime stabilization is the better stabilizer in terms of strength development. The unconfined compressive strength and California Bearing Ratio values of enzymatic lime stabilized samples have increased up to 5 and 30 times in the case of kaolinite mineral, but to only less than 1.5 times in the case of bentonite mineral. The study thus indicates that enzymatic lime stabilization is predominantly effective for clays containing kaolinite minerals.  相似文献