Environmental Engineering Reference
where V 1 is volume of sample bottle after placing the stopper, V 2 is volume of the
part of the contents titrated and V is volume of MnSO 4 and KI added.
( e ) Total calcium (EDTA method): 50 ml of sample water was taken in a conical
flask and 0.1 ml of 8 % NaOH along with few drops of indicator (Murexide indica-
tor) was added to it and the colour changed to pink (Munshi and Munshi 1995 ). This
was titrated with EDTA (0.01 M) till the colour turned purple.
( f ) Total Hardness (EDTA method): 50 ml of sample water was taken in a conical
flask. Added 1 ml of ammonia buffer (Sigma Aldrich - product code 318604) along
with five drops of indicator (Eriochrome black T) (Munshi and Munshi 1995 ).
Above solution turns wine red. Titrated the above solution by EDTA (0.01 M) until
clear blue colour appears.
( g ) Total magnesium hardness = Total hardness - calcium level (Munshi and
Munshi 1995 )
( h ) Total chlorides: Chlorides were estimated by the method of Munshi and
Munshi ( 1995 ). In short about 50 ml of water sample was taken in a conical flask
and 2 ml of potassium chromate indicator was added. The solution was titrated
against standardized silver nitrate (0.01 N) until a brick red colour precipitate of
silver chromate started appearing. The volume of silver nitrate consumed was noted
down and amount of chloride was calculated with following equation:
Free Cl mg L lNof AgNO
1 000 35 5
Electrical conductivity (EC) and total dissolved solids (TDS) (Systronic - soil
and water analysis kit - model director new BC) and turbidity - Nephelometeic
method (Systronic - digital nephlo-turbidity meter 132) were determined using
available electronic instruments.
Fish Population Estimates
Data on fish populations was obtained from sampling sites established during the
original survey. These sites were chosen to capture the existing range of fish com-
munities (e.g., dominated by native fishes vs. exotic fishes) as well as the range of
habitat types and quality. Fish were sampled using a combination of hired fisherman
and other efforts (e.g., three pass depletion technique), and population estimates
were completed based on modified depletion technique (Zippin 1958 ). For fish pop-
ulation estimates, a specifically marked area of 800 m to 1 km was quardened off
with nets and then the sampling was conducted. All the sample collections and
measurements were done from these specifically marked sites.
Statistical comparisons were done using Origin 8.6 software from origin labs.