1980 - National Institute of Oceanography

4. Monitoring activities in and around Goa
Monthly monitoring activities of several environmental parameters have been
initiated in the rivers Mandovi and Zuari. Four stations extending from the salt water
to the fresh water zones in both the rivers were sampled at mid-depth. The parameters
monitored were: pH, O2, temperature, salinity/chlorinity, Ca 2+ , Mg 2+ , SO4 2- , F - ,
PO4 3- -P, NO3 - -N, Hg, Mn and Fe. The last three parameters were monitored in all
the three phases (dissolved, particulate and sediments)
Monitoring activities were continued in the Velsao Bay also for the different
forms of nitrogen compounds.
5. Pollution monitoring along the Kerala coast
Studies carried out under this investigation are reported separately under
Section 3.8.1.
6. Marine environmental monitoring along the Bombay coast.
The details of this investigation are given under Section 3.8.2.
3.2.4 Characteristics of the estuarine regions of major rivers of India
A new multi-disciplinary project to survey the environmental features in the
estuarine region of 7 major Indian rivers was initiated during the year. One set of
observations has been completed in September, 1980 in the estuarine region of the
river Hooghly, from Diamond Harbour to Sandheads (a distance of approximately
60 nautical miles) and also at a station off the mouth of the river Mahanadi.
Each station was worked over a tidal cycle of 12 hours to measure temperature,
salinity, current speed, current direction, dissolved oxygen, phosphate-phosphorus,
nitrate-nitrogen, ammonia.-nitrogen and suspended solids. The nutrients, dissolved
oxygen and suspended solids were measured at individual collection every 3 hours
at 3 depths. A composite sample at mid-depth over the tidal period was also collected.
Current direction at the Diamond Harbour was SE-NNW (134°-344°) turning
210° over the tidal cycle. The values at Haldia were SE-ENE (222°-071°) turning
151° and at Sagar SW-SSE to N-NNE (192°-011°) turning 179° over the tidal cycle.
This shows that the currents turned almost 180° at all the stations. At the Diamond
Harbour and Haldia, salinity values were 0.09 and 0.8l%o respectively, while at Sagar
during the ebb tide, a layer of low salinity water of about 8%o was observed in
the upper 7 metres. Similarly a layer of a higher salinity water of about 14%o upto
15 metres depths was observed.
Comparing the nutrient values with tidal fluctuation, it was observed that in
general, at all the 3 stations, the values were higher during the ebb tide and lower
during the flood tide indicating a net transport of the nutrients seawards. However,
a proportionate increase of these values was not observed at the Sandheads station. This
probably indicates that a major portion of the nutrients along with the enormous
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