How polluted is the Hussainsagar lake in Hyderabad? The lake bed as well as surface water is highly polluted

Syed Akbar
Hyderabad:  Everyone knows that Hussainsagar surface water is
polluted but what many do not know is that the bed of the historic
lake too is highly polluted making it environmentally poisonous for
aquatic life and birds.

City researchers Prof M Vikram Reddy and Dr A Vijay Kumar collected
samples of Hussainsagar water and its sediment and conducted analysis
for harmful elements before and after the Ganesh immersion ceremony.
The surface water of the lake is less polluted as compared to its bed
surface.

They found that the pH, which determines the quality of water, has
increased to 8.35 (alkaline) after immersion of Ganesh idols from 7.40
before immersion. The electric conductivity has almost doubled from
2.535 to 4.750 while the total dissolved solids increased from 1534 to
2695 mg/l.

The concentration of chlorides increased from 25.50 mg per litre to
73.15 mg/l, while the content of lead went up from 0.376 to 0.575
mg/l. Similarly, manganese concentration went up from 18.50 mg/l to
24.56. Nitrogen concentration increased from 5.23 mg/l to 18.56.

"About 20,000 tonnes of plaster of Paris and coloured chemicals, 300
tonnes of iron and 100 tonnes of wooden planks are immersed in the
lake every year. The immersion of thousands of multi-coloured idols of
various sizes have significant effect altering the water quality of
the lake," said Dr A Vijay Kumar.

The content of calcium, iron, magnesium, molybdenum and silicon in the
surface water of the lake exceeds the standards fixed by the BIS and
ICMR. The concentration of most of these elements in several orders of
magnitude is higher in the bottom sediment of the littoral zone of the
lake than in the overlying surface water.

The team noticed that some elements like chromium, cobalt, nickel,
copper, zinc, cadmium, lithium, boron and selenium have vanished and
the concentration of manganese and sulphur dropped considerably from
the surface water following Ganesh idol immersion. The disappearance
of these elements following idol immersion can be attributed to the
absorption processes of the dissolved metal oxides metal ions by the
materials, particularly the coloured chemical hydrous metal oxides
used in paintings, varnishes and water colours on the idols.

"We have recorded significantly higher concentrations of all these
elements in the surface sediment of the lake compared to that of
surface water. Japan Bank for International Cooperation has consented
to fund cleaning of the lake. But, it is foolish to think about the
purification of water when we continue to pollute them knowingly," he
pointed out.