Water quality assessment with reference to heavy metals in surface and sub-surface water of “Urban Delhiâ€
Student name: Ms Shoobhangi Tyagi
Guide: Dr Vinay Kumar Tyagi
Year of completion: 2016
Host Organisation: Department of Environmental Studies, University of Delhi
Supervisor (Host Organisation): Dr Chirashree Ghosh
Abstract: Globally, water pollution has become one of the major area of concern these days. Several
biodegradable and non- biodegradable pollutants (such as heavy metals) entering into the water
body from different anthropogenic sources are responsible for the deteriorating water quality.
From the water body metals are adsorbed by the sediments which further gets bio accumulated
by the plants and enters into the food chain. The undertaken study aimed to envision the water
quality of sub surface and surface water of Urban Delhi with respect to Heavy metal
contamination by computing Heavy Metal Pollution index (HPI) and Water Quality Index
(WQI). Special focus has been given to mercury toxicity and its bio availability in plants and
sediments which was determined by calculating the Bio Accumulation factor (BAF) of mercury
along the urban stretch of river Yamuna. The impact of water pollution on the bio- diversity of
this region was also estimated using Sequential Comparison Index (SCI). To understand
people’s perception regarding heavy metal pollution a community survey using questionnaire
has been conducted in 11 districts of Delhi.
The analysis reveals that the HPI values were much closer to the critical value of 100 and the
WQI values were greater than 50 suggesting that both surface and sub – surface water of urban
Delhi are of poor quality. Further it can be seen that the quality of water degrades as one moves
from the upstream of the river to downstream owing to impact of various anthropogenic sources
and input from urban drainage system. The mercury concentration in the water was exceeding
the permissible limit of less than 1ppb and the bio accumulation factor of mercury was found to
be quite high suggesting that human health is at risk of Hg toxicity. The impact of metal
contamination on the bio diversity of the region can be realized by seeing the high values of SCI
across the Yamuna floodplain. Moreover from the survey analysis it can be seen that most of the
people are ignorant regarding metal pollution and its related health impact. The results from
this study suggests that there is an immediate requisite to take strict action for the prevention
and mitigation of metal contamination in water.
Keywords: Heavy metal pollution index, Water Quality Index, Sequential Comparison Index,
Mercury toxicity, Bio accumulation factor.
