Productivity of Backwaters and Estuaries
rs.o
c
~4. 0
III
23.0
o
.r.
~2.0
o
.r.
a.
u 1.0
·c
o
e' 0 ......... .,-L ........ ...,-J'-r-....... -'--r-'-.-L.,--L.,.L ........ ...,-J-l
o
D
149
Fig. 11. Average monthly values of organic phosphorus at 2 different depths of the backwater.
Surface: closed circles; bottom: open circles
10. Nitrate-Nitrogen
When the backwater remains marine-dominated the values of N03 - -N are low, but
during the monsoon months the values become suddenly high. The distribution of
N03 - -N remains homogeneous throughout the water column in all the seasons (Fig. 12) .
.::- 30
!....
Fig. 12. Average monthly values of nitrate-nitrogen at 3 different depths of the backwater. Symbols
as in Fig. 5
11. Nitrite-Nitrogen
Pronounced changes in the N02 - -N were noticed during the monsoon months
(Fig. 13) but these were mostly in deeper layers. The water at the surface showed
maximum value in May whereas three peaks of N02 - -N were recorded at mid-depth and
at the bottom (Fig. 13).