Pollution by fly ash: Vijayawada outskirts faced with the problem of highly radioactive isotopes of Radon 226, Thorium 228 and Potassium 40

By Syed Akbar
Hyderabad: People living within a radius of 10 km from
Vijayawada Thermal Power Station are exposed to highly radioactive
isotopes of Radon (R 226), Thorium (Th 228) and Potassium (K40) and
heavy metals like lead, mercury and cadmium.

Latest research studies on ground water and soil samples collected
from habitation within a radius of 10 km of the fly ash pond of the
thermal power station revealed that a cocktail of dangerous
radionuclides and heavy metals makes its way into the soil and the
ground water table. The Krishna River, which flows in the vicinity,
also carries a portion of these harmful substances downstream. The
VTPS is now in search of a new pond to pump in fly ash as the existing
pond is almost filled to the brim.

Harmful substances like sodium, sulphates, arsenic, selenium,
molybdenum, chromium and lead are found in higher quantities in areas
affected by fly ash pollution than in non-polluted places. Some of
these substances exceed the safe upper limit prescribed by the World
Health Organisation. There was leaching of zinc, lead, and iron from
the VTPS ash pond into the ground water. The problem gets worse during
rainy season when the leaching of ions is relatively higher due to
ground water recharge.

“Water samples within a distance of 10 km around the thermal power
station showed an increase in total dissolved solids, calcium
hardness, magnesium, total hardness, chlorides and alkalinity. These
substances also made their way to plants through a process called
bio-accumulation,” points out a research study conducted by the Centre
for Ecological Sciences (CES), Indian Institute of Science, Bengaluru.
The energy and wetlands research group of the CES conducted studies on
various thermal power plants in the country including VTPS.

The CES researchers said leachate from fly ash ponds into the ground
water table has genotoxic potential and may lead to adverse effects on
vegetation and on the health of exposed human populations. They damage
the delicate DNA in the blood cells. Damage to DNA was also observed
in plants.

Studies near the VTPS fly ash dumpsites showed the contamination
increased in the case of toxic ions with the passage of time. The fly
ash, a waste product obtained from coal burning in thermal power
stations, also contains substances like polycyclic aromatic
hydrocarbons, which cause cancer in human beings. The radionuclides of
radon, thorium and radioactive potassium were found to be in the range
of 40.7 to 151.7 Becquerel per kilogram, 96.2 to 177.7 and 148 to 840
Becquerel per Kg respectively. This is quite higher than the
permissible limits.