Sujatha, C H; Anu, Gopinath; Neema, Joseph; Nair, S M(Taylor & Francis, September 14, 2010)
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Abstract:
The distribution of three important dissolved forms of nitrogen, viz. nitrate, nitrite and urea in the surface and bottom
water samples collected from 27 selected hydrographic profiles, in the Arabian Sea, along the west coast of India is
described. Of the three forms, nitrate concentrations were the highest and comparatively higher concentrations were
observed in the bottom water. Decomposition of organic matter resulting in the release of the thermodynamically
stable nitrogen species, i.e. nitrate, may be the major factor resulting in higher nitrate concentrations at these
depths, where the water is also characterized by low values of dissolved oxygen and temperature. The significant
positive correlation between A.O.U. and nitrate of the bottom water samples emphasizes the role of oxidative
decomposition of organic matter which plays an active role in reducing the oxygen concentrations below the
theoretical values since at this depth ( 200 m) the net production is taken to be zero. This is also evidenced by
the negative correlation of nitrate with dissolved oxygen and temperature, for the bottom samples
Description:
Chemistry and Ecology, 2002, Vol. 18(3–4), pp. 233–244
Sujatha, C H; Nify, Benny; Ranjitha, Raveendran; Fanimol, C L; Samantha, N K(December , 2009)
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Abstract:
Distribution and chemistry of major inorganic forms of nutrients along with physico-chemical parameters were
investigated. Surface sediments and overlying waters of the Ashtamudi and Vembanad Lakes were taken for the study,
which is situated in the southwest coast of India. High concentrations of dissolved nitrogen and phosphorus compounds
carried by the river leads to oxygen depletion in the water column. A concurrent increase in the bottom waters along with
decrease in dissolved oxygen was noticed. This support to nitrification process operating in the sediment-water interface of
the Ashtamudi and Vembanad Lake. Estuarine sediments are clayey sand to silty sand both in Ashtamudi and Vembanad in
January and May. Present study indicates that the sediment texture is the major controlling factor in the distribution of these
nutrient forms. For water samples nitrite, inorganic phosphate was high in Vembanad in January and May compared to
Ashtamudi. For sediments, enhanced level of inorganic phosphate and nitrite was found in Vembanad during January and
May. It had been observed that the level of N and P is more in sediments. A comparative assessment of the Ashtamudi and
Vembanad Lake reveals that the Vembanad wetland is more deteriorated compared to the Ashtamudi wetland system
Description:
Indian Journal of Marine Sciences
Vol. 38(4), December 2009, pp 451-456