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1.
C. M. Laluraj K. K. Balachandran P. Sabu S. U. Panampunnayil 《Marine Geophysical Researches》2006,27(4):283-288
This study delineates the formation of a warm pool (>34°C) of air to the west (downwind) of the active volcano of the Barren Island during October–November 2005. Barren Island is located in the Sumatra–Andaman region, about 135 km east of Port Blair, and lies within the Burma microplate, the southern tip of which experienced a submarine earthquake (M
w 9.3) causing a tsunami in December 2004. Barren Island is the only volcano, which has shown sustained eruptive activity since shortly after the Great Sumatran Earthquake of December 2004. Our observations require further corroboration to relate how submarine earthquakes activate volcanoes and how far these thermal emissions influence climate changes. Because it links global warming and climate changes to the frequent emissions from a volcano activated by submarine earthquakes, this case study is of special interest to the earth-ocean-atmosphere sciences community. 相似文献
2.
K. K. Balachandran 《Estuarine, Coastal and Shelf Science》2004,59(4):589-598
Coastal waters off the southwest coast of India draw special attention because of the occurrence of mud banks at certain locations during southwest monsoon period. The present study puts forward a hypothesis of a subterranean flow, which could be a plausible mechanism to initiate the mud banks. The subterranean flow is believed to be coupled with activated trending faults and originate from the adjacent watershed (Vembanad Lake) separated from the sea by a narrow strip of land where submerged porous lime shell beds are present. When the lake water injection occurs through the fault, the mud/clay gets excited by its thixotrophic properties (as the overlying water looses its electrolyte) and transforms into a flowing fluid. The lowering of salinity due to the introduction of fresh water keeps the mud suspension in the water column for longer duration, leading to the formation of mud banks. The idea of subterranean flow through lime shell beds initiating formation of mud banks may apply globally to any coastal regions hugged by wetlands and of similar geological conditions. 相似文献
3.
Joereen Miranda K.K. Balachandran R. Ramesh Mohideen Wafar 《Estuarine, Coastal and Shelf Science》2008
Nitrification rates, as oxidation of 15N-labelled ammonium and loss of nitrite from N-Serve treated samples, were measured in Kochi backwaters during three seasons. Nitrification rates ranged from undetectable to 166 nmol N L−1 h−1 in the water column and up to 17 nmol N (g wet wt)−1 h−1 in sediments. Nitrification rates were higher in intermediate salinities than in either freshwater or seawater end. Within this salinity range, nitrification rates could be related to ammonium concentrations. As shown by the relation between ammonification and nitrification rates, it is also likely that nitrification is more regulated by renewal rates, rather than by in situ concentrations, of substrate. Among other environmental parameters, temperature and pH may have an influence on nitrification. Potential nitrification rates calculated from loss of nitrite from N-Serve treated, nitrite-enriched samples were about 800 nmol N L−1 h−1 in the water column and 40 nmol N (g wet wt)−1 h−1 in sediments. While these rates are in balance with those of biological ammonium production they may be inadequate to mitigate ammonium pollution in this estuary. 相似文献
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5.
Since the 1970s, the Solar-Terrestrial Environment Laboratory, Japan, has been publishing synoptic maps of solar wind velocity prepared using the technique of interplanetary scintillation. These maps, known as V-maps, are useful to study the global distribution of solar wind in the heliosphere. As the Earth-orbiting satellites are unable to probe regions outside the ecliptic, it is important to exploit the scope of interplanetary scintillation to study the solar wind properties at these regions and their relation with coronal features. It has been shown by Wang and Sheeley that there exists an inverse correlation between rate of magnetic flux expansion and the solar wind velocity. The NOAA/Space Environment Center daily updated version of the Wang and Sheeley model has been used to produce synoptic maps of solar wind velocity and magnetic field polarity for individual Carrington rotations. The predictions of the model at 1 AU have been found to be in good agreement with the observed values of the same. The present work is a comparison of the synoptic maps on the source surface using the interplanetary scintillation measurements from Japan and the NOAA/SEC version of the Wang and Sheeley model. The two results agree near the equatorial regions and the slow solar wind locations are consistent most of the times. However, at higher latitudes within ±60°, the wind velocities differ considerably. In the Wang and Sheeley model the highest speed obtained is 600 km s–1 whereas in the IPS results velocities as high as 800 km s–1 have been detected. The paper discusses the possible causes for this discrepancy and suggestion to improve the agreement between the two results. 相似文献
6.
Summary In this paper the modulation of storm and depression tracks over North Indian Ocean by the Quasi-Biennial Oscillation (QBO)
of zonal winds in the equatorial stratosphere is discussed for the period 1953–1991. It was observed that during post monsoon
season the storms and depressions of Bay of Bengal were mostly confined to south of 17° N and move in west/North-westward
direction during easterly phase of QBO. However during the westerly phase no such similar type influence of QBO on the system
tracks was observed. Also such type of QBO-System tracks association was not observed during pre-monsoon season.
Received February 6, 1998 Revised January 20, 1999 相似文献
7.
Acta Geotechnica - Dry granular materials have been the subject of many investigations, while wet granular materials, which widely exist in many real-world applications, have only received limited... 相似文献
8.
Shoji D. Thottathil K.K. Balachandran G.V.M. Gupta N.V. Madhu Shanta Nair 《Estuarine, Coastal and Shelf Science》2008
Bacterial productivity (BP) and respiration (BR) were examined in relation to primary productivity (PP) for the first time in a shallow tropical ecosystem (Cochin Estuary), India. The degree of dependence of BP (6.3–199.7 μg C L−1 d−1) and BR (6.6–430.4 μg C L−1 d−1) on PP (2.1–608.0 μg C L−1 d−1) was found to be extremely weak. The BP/PP (0.05–8.5) and PP/BR (0.02–7.9) ratios widely varied in the estuary depending on the season and location. There was a seasonal shift in net pelagic production from autotrophy to heterotrophy due to terrestrial organic matter input through rivers which enhanced the bacterial heterotrophic activity and very high pCO2 (106–6001 μatm) levels. The heterotrophic zones were characterized by low PP but high bacterial production and respiration leading to oxygen undersaturation and exceptionally high pCO2. We propose that the CO2 supersaturation caused by increased bacterial respiration (in excess of PP) was a result of bacterial degradation of allochthonous organic matter. This indicates that sources other than planktonic compartment need to be explored to understand the C-cycling in this estuary. These results are of particular relevance to tropical ecosystems in general, where the bulk of world's river discharges occur. 相似文献
9.
M. Nair J. Jacob P. A. Nisha G. D. Martin K. Srinivas P. Sheeba C. M. Laluraj T. Joseph K. K. Balachandran 《Environmental Earth Sciences》2010,61(1):27-35
Temporal and spatial changes in the sediment properties of a mangrove ecosystem (Cochin, southwest coast India) are presented.
The region was freshwater dominated during monsoon (June–September) and seawater dominated during other two seasons. The system
remained eutrophic due to the high inputs of organic matter (OM) during most part of the year. The organic-rich sediments
accumulated high amount of carbohydrates (22% of OM) and proteins (11% of OM) during non-monsoon months as compared to coastal
environments. Principal component analysis showed that the biochemical properties are uniformly influenced by seasonal and
spatial variations. Higher concentrations of sediment protein over carbohydrate indicate an efficient mineralization leading
to the non-availability of aged OM in the system. The dominance of these labile components is generally indicative of the
eutrophic condition of the system. 相似文献
10.
Tidal switch on metabolic activity: Salinity induced responses on bacterioplankton metabolic capabilities in a tropical estuary 总被引：3，自引：0，他引：3
Shoji D. Thottathil K.K. Balachandran K.V. Jayalakshmy G.V.M. Gupta Shanta Nair 《Estuarine, Coastal and Shelf Science》2008,78(4):551
“Biolog” plates were used to study the changes in the metabolic capabilities of bacterioplankton over a complete tidal cycle in a tropical ecosystem (Cochin Estuary) along southwest coast of India. The pattern of utilization of carbon sources showed a definite shift in the community metabolism along a salinity gradient. Multivariate statistical analysis revealed two communities, namely allochthonous bacterioplankton sensitive to salinity and autochthonous bacterioplankton, which are tolerant to wide salinity fluctuations. Regression analysis showed salinity as the most important parameter influencing the physiological profile of bacterioplankton, irrespective of tide. Apart from salinity, limno-tolerant retrievable counts and halo-tolerant retrievable counts also accounted for the metabolic variation of bacterioplankton during low and high tides, respectively. The shift in the substrate utilization from carbohydrates to amino acids appears to be due to the physiological adaptation or nitrogen limitation of bacterial community with increasing salinity. 相似文献