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Graded series of concentrations of the Paper mill effluent was prepared for

toxicity studies with nutrient medium as the diluents. Pure algal cultures were inoculated in
to control and exposed flasks in a Laminar air flow to maintain aseptic conditions. The

effluent was initially UV irradiated. After 15days of exposure, the toxicity values were
deduced for all the three algae tested. Approximately 3.85% effluent concentration was

selected (sub-lethal dose) for the experimental purpose. All the three selected algae were
inoculated and allowed to grow for 15days and after 15days, the algae were harvested and

one set was taken for metal analysis and the second set was taken for pigment studies.

Table-3: Showing the changes in pigment content of three algae exposed to paper mill
effluent collected from station S3 and residual accumulation of mercury and cadmium

after 15days of exposure in laboratory controlled conditions. Values in parentheses indicated

percent decrease in parameters, when compared to its respective control values.
[UC=Uncontaminated (Control), E=Exposed, ND=Not detected].

Laboratory experimental study: (Exposure period 15days)
BGA studied Status Residual Residual Total Total Total

mercury cadmium chlorophyll phaeophytin carotene

-1
-1 -1 (mg l ) (mg l ) (mg l )
-1
-1
(mg g (mg g
dry wt ) dry wt )
Anabaena UC ND ND 24.8±6.2 26.6±9.4 16.8±7.3

cylindrica, E Lemm 4.1±0.9 5.1±1.1 6.2±5.4 7.8±6.1 3.4±1.8

(-75.0) ( -70.7) ( -79.8)

Nostoc UC ND ND 26.6±9.2 29.4±6.8 17.2±5.6

muscorum, E 3.9±1.2 4.2±0.8 9.4±2.2 8.2±2.9 1.8±0.6

C.Agardh ( -64.7) ( -72.1) ( -89.5)

Westiellopsis UC ND ND 28.4±9.2 29.2±5.8 17.4±9.2

prolifica, E Janet 3.8±1.3 4.6±1.1 7.6±2.6 8.1±3.8 2.8±1.1

( -73.2) ( -72.3) ( -83.9)

During exposure to the effluent of the paper mill, the algal cells initially could not grow
normally but after 3 rd day of exposure, the growth was normal. Anabaena, Nostoc and

Westiellopsis accumulated mercury to the tune of 4.1±0.9 mg g dry wt; 3.9±1.2 mg g dry
-1
-1

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