mercury pollution

1. Studies of mercury pollution in a lake due to a
thermometer
factory situated in a tourist resort: Kodaikkanal,
India
RAVI KUMAR
2009JE0618

2. • Introduction
• Sources of mercury
• Forms of mercury and method
to detect
• Fick’s Law and its role
• Aquatic Mercury Cycle
• Geochemical characteristics
• Kodaikkanal mercury
pollution
• Conclusion

3. INTRODUCTION
• Non-essential element
with no biochemical or
nutritional function to bio
organisms.
• Mercury is persistent.
• All forms of mercury are
extremely toxic.
• Methylated mercury –
bioaccumulation and
biomagnification.

4. SOURCES OF MERCURY
•Natural Sources- volcanoes, geologic
deposits of mercury, and volatilization from
the ocean.
•Anthropogenic Sources- Alkali and metal
processing, incineration of coal, medical and
other waste, and mining of gold and
mercury.

5. FORMS OF MERCURY AND
METHOD TO DETECT
• FORMS – Hg, Hg(II), MeHg.
• METHOD- Mercury was analysed by
cold vapour atomic absorption
spectrometry (CV-AAS) using a
mercury analyser.

6. FICK’S LAW
• The diffusion first Fick law allows the
estimation of the diffusive fluxes (J) across
water–sediment interface, by constructing a
linear gradient of the solute concentration (C)
in pore water at the 0–0.5cm layer (Z):
Where DAB=Diffusion Constant.

7. Table– Quantities of reactive and non-reactive mercury (nmolm2 (12 h)1 and mmolm2 (12 h)1,
respectively) present in the Largo do Laranjo water column and estimation of the pore waters
contribution to the enrichment of the water column (%)
Zone A Zone B Zone C Zone D
Mercury present in water column
Reactive Hg (nmolm2 (12 h1)) 394 396 318 150
Non-reactive Hg (mmolm2 (12 h1)) 2.99 3.35 2.18 2.34
Contribution of pore waters to enrichment of water column
Reactive Hg (%) 0.016–0.17 0.006–0.12 0–0.012 0.027–0.030
Non-reactive Hg (%) 0.064–0.50 0.010–0.054 0.007–0.033 0.005–0.056

8. GEOCHEMICAL CYCLE

9. GEOCHEMICAL CHARACTERISTICS

10. KODAIKKANAL MERCURY
POLLUTION
• Mercury contamination originating
from a thermometer making factory.
• Present study determined total
mercury and methyl mercury in
water, sediment and fish samples
and compared the values with those
from two other lakes, Berijam and
Kukkal.

12. • Ambient levels of mercury in air of
1.32 mg/m3 were found immediately
outside the factory premises.
• Outside the premises of the factory,
the mercury levels in the lichen and
moss were 7.9 mg/kg and 8.3 mg/kg
respectively.
• Mercury vapour once released into
the air is known to travel long
distances leading to widespread
contamination.

13. • Kodai sediment showed 276-350
mg/kg HgT with about 6% methyl
mercury. Berijam and Kukkal
sediments showed HgT of 189-226
mg/kg and 85-91 mg/kg and lower
methylation at 3-4% and 2%,
respectively.
• HgT in fish from Kodai lake ranged
from 120 to 290 mg/kg.

14. • Analysis of water, sediment and fish
samples from Kodai Lake from the
tourist resort of Kodaikkanal, India,
showed elevated levels of mercury
even 4 years after the stoppage of
mercury emissions from the
thermometer factory that operated
for 18 years and was closed down
subsequently in 2001.
• This shows that mercury is retained