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| Articles
by
Lopa Ghosh |
Total Records (
4 ) for
Lopa Ghosh |
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Lopa Ghosh
,
G.N. Tiwari
,
Tribeni Das
and
Bikash Sarkar
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An analytical model is presented to study the effectiveness
of a low cost arch shape greenhouse used for heating the fishpond during
extreme winter. The model was solved for the climatic conditions of New
Delhi (Latitude-28° 35/ N, Longitude-77° 12/
E and an altitude of 216 m above mean sea level). Parametric studies involved
the effects of different greenhouse fishpond related parameters including
depth of pond water, transmissivity of greenhouse cover and number of
air changes in the greenhouse on water heating in the fishpond. The thermal
performance of fishpond was assessed in terms of thermal load leveling.
A 4.76-5.83°C rise in water temperature could be achieved as compared
to open pond of the day. The maximum heat gain and loss are around 14:00
to 17:00 and 1:00 to 7:00 h of the day, respectively. From production
point of view greenhouse fish pond showed better performance compared
to open pond. |
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Lopa Ghosh
and
G.N. Tiwari
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This study presents modeling of dissolved
oxygen performance in a greenhouse fishpond. A short-term Disolved Oxygen
(DO) fluctuation of a fishpond was developed by using various simple equations
and continuous measurement of DO, temperature and solar intensity. Numerical
computation has been performed for a typical winter day at the month of
January, 2007. Components considered in the DO model include the production
of DO by phytoplankton and consumption of oxygen by phytoplankton, fish,
water column and sediment. Numerical equations were solved with Excel
soft ware to predict DO in the pond. Initial slope (α) and Pmax
were calculated from DO production Vs. solar radiation curve. The amount
and distribution of oxygen production in the water column depend on solar
intensity and penetration as well as phytoplankton concentration. A parametric
study has been performed to represent the effects of pond depth, SDD,
extinction coefficient, water temperature and fish yield changes on DO
regimes in fish pond. Dissolved oxygen concentrations in the pond varied
with both pond depth and SDD. By increasing the depth of the pond and
of the SDD and maintaining phytoplankton chlorophyll-a concentration at
232 μg L-1, the overall oxygen production was increased.
The low DO values in the shallow pond (0.5 m) with a high SDD (0.5 m)
when compared to other ponds with SDD equal to their pond depths, was
the result of low overall oxygen production relative to the demand by
sediment and fish which were same for all depths of pond. Predicted and
experimental DO concentrations exhibited fair agreement with correlation
coefficient of R = 0.99 and root mean square percent deviation e = 3.73%.
Such correlation between predicted and experimental data indicates that
the assumption inherent in the computer model of the processes is valid
for the DO production and consumption in the pond. |
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Lopa Ghosh
,
S. Adhikari
and
S. Ayyappan
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The present investigation deals with the distributions of three heavy metals, lead (Pb), cadmium (Cd) and chromium (Cr) in sediment and their availability in tissues of Labeo rohita (Hamilton) fingerlings. This study showed that Cd was available in exchangeable and carbonate fractions of the sediment, where as Pb and Cr was mainly existed in organic and residual organic fractions. This study revealed that Pb and Cr were more in gill tissues, while Cd was mainly concentrated in viscera. Significant relationships (p<0.05) between metals in different chemical fractions (exchangeable, carbonate, Fe-Mn oxide, organic and residual) of sediment and metals in fish organs (Pb in all organs, Cd in muscle, skin and viscera and Cr in muscle and gill) were found. |
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