Chandramohanakumar, N; Renjith, K R; Manju, Mary Joseph(Springer, May 7, 2010)
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Abstract:
Phosphorus fractionation was employed
to find the bioavailability of phosphorus and its
seasonal variations in the Panangad region of
Cochin estuary, the largest estuarine system in
the southwest coast of India. Sequential extraction
of the surficial sediments using chelating agents
was taken as a tool for this. Phosphate in the
water column showed seasonal variations, with
high values during the monsoon months, suggesting
external runoff. Sediment texture was found to
be the main factor influencing the spatial distribution
of the geochemical parameters in the study
region. Similarly, total phosphorus also showed
granulometric dependence and it ranged between
319.54 and 2,938.83 μg/g. Calcium-bound fraction
was the main phosphorus pool in the estuary.
Significant spatial variations were observed for
all bioavailable fractions; iron-bound inorganic
phosphorus (5.04–474.24 μg/g), calcium-bound inorganic
phosphorus (11.16–826.09 μg/g), and acidsoluble
organic phosphorus (22.22–365.86 μg/g).
Among the non-bioavailable phosphorus, alkalisoluble
organic fraction was the major one (51.92–
1,002.45 μg/g). Residual organic phosphorus was
K. R. Renjith (B) · N. Chandramohanakumar · M. M. Joseph
Department of Chemical Oceanography, School
of Marine Sciences, Cochin University of Science
and Technology, Kochi 682016, Kerala, India
e-mail: renjithaqua@gmail.com
comparatively smaller fraction (3.25–14.64% of
total). The sandy and muddy stations showed
distinct fractional composition and the speciation
study could endorse the overall geochemical character.
There could be buffering of phosphorus,
suggested by the increase in the percentage
of bioavailable fractions during the lean premonsoon
period, counteracting the decreases in
the external loads. Principal component analysis
was employed to find the possible processes
influencing the speciation of phosphorus in the
study region
Chandramohanakumar, N; Renjith, K R(Taylor & Francis, August 9, 2007)
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Abstract:
Geochemical characteristics of surficial sediments in the Panangad region of Cochin estuary, the largest
brackish-water humid ecosystem in the south-west coast of India, were analysed. Temporal variations
in nutrient stoichiometry, seasonal characteristics of redox elements Fe and S, and the phosphorus geochemistry
were employed for the purpose. The stoichiometric analysis pointed towards autochthonous
origin of organic matter, possibility of nitrogen limitation, and allochthonous modification of redox
conditions. Seasonal variations were not statistically significant for all the geochemical parameters,
whereas significant spatial variations were observed with lower values at sandy stations, suggesting
that the texture of the sediments is the main factor influencing the sediment geochemistry. Significant
inter-relations between the geochemical parameters also suggest a common control mechanism. Based
on these geochemical characteristics, the study region can be effectively categorized into two distinct
zones, viz. (1) erosion and transportation and (2) deposition zones
Description:
Chemistry and Ecology
Vol. 23, No. 4, August 2007, 337–345