Water an essential requisite of an ecosystem for the sustainability of life on earth. Hydrological parameters, important
components of water are essential for the analysis of water quality that provides information about the changes caused
by anthropogenic activities and also by different seasons throughout the year. The two lakes, Vengaiah lake (Lake A) and
Yellamalappa Chetty lake (Lake B) taken for the study are located in Bangalore city, important for charging the groundwater
and also are the source of livelihood for local fishing community. The aim of present investigation was to assess the water
quality of the two selected lakes, by determining their physicochemical parameters, such as temperature, turbidity, acidity,
alkalinity, TDS, TSS, DO, BOD, COD, nutrients (total phosphorus and nitrate) and trace metals. These parameters were assessed
seasonally for their pollution and trophic status. The data revealed eutrophic condition of lake A due to the presence of high
concentration of turbity, conductivity, TDS, TSS, alkalinity, total phosphorus & BOD since it received domestic sewage from
the adjacent storm water drain whereas lake B showed statistically significant variation in the levels of all physico-chemical
parameters when compared to standard values. Presence of trace metals such as copper, zinc and iron and heavy metals such
as aluminum, cadmium, lead and mercury due to contamination caused by human interference and discharge of partially
treated and untreated industrial effluents from neighboring pharmaceutical industry into the lake B was recorded and such
changes were prominent during the summer, rainy and winter season. Consequently, lake B showed a high level of pollution
when compared to that of lake A, which may be due to the level of trace metals more than the standard BIS permissible limits
and low levels of dissolved oxygen. Standard values for freshwater bodies given by BIS: 10500-1991 (revised 2003) were used
for the comparison of water quality in general. |