HEAVY METALS AND ITS BIOACCUMULATION

1. TOPIC BIO-ACCUMULATION OF HEAVY
METALS
Definition .
Accumulation of heavy metals in different
organisms like in humans and animals etc is called bio-
accumulation of heavy metals .
These heavy metals maybe lead ,
cadmium , mercury , cobalt , nickel , arsenic , cesium
and antimony etc .
All these metals are toxic . Heavy metals are not
micronutrients and not macronutrients . In humans ,
animals and plants , these heavy metals cause
diseases .

2. Major source of heavy metals release are ,
 Natural source like rocks , volcanic eruption , dust
particles , aerosols and sea spray etc .
 Agricultural source like inorganic fertilizers , pesticides ,
waste water , fungicides and sewage sludge etc .
 Industrial source like thermal power , industrial waste ,
mining industry , refineries and chemical industry .
 Domestic source like organic waste , inorganic waste ,
biomass burning , used filters and used batteries .
 Miscellaneous like landfills , medical waste , traffic
emissions etc .
The upper discharge of heavy metals is in
the form of liquid , gas and solid .

3.  Effect of bio-accumulation in aquatic organism .
 Heavy metals in the fishes disturb their growth and reproduction.
 And heavy metals cause the alternation in the gills , skin , liver ,
spleen and kidneys of fishes
 In some cases , their survival chances also decreases due to
accumulation of heavy metals .
For example ,
Shell-fish does not have any mechanism to prevent
the accumulation of heavy metals .That is the reason that shell-fish
is used as the indicator to determine the heavy metals ratio in a
certain area by the scientists .
Still much work is needed to be done to develop the reliable methods of
detecting the presence of unacceptable level of heavy metals .

4. Effect of bio-accumulation in humans .
1. Lead , Cadmium , Co , Ni and Hg in human affect the formation of blood
cells .
2. It also causes the malfunctioning of the liver , kidneys and circulatory
system .
3. Heavy metals also affect the movement of nerve signals .
4. Heavy metals in human also play a role in the development of various
cancers .
5. Mercury in the form of methyl-mercury is very dangerous because it
affects liver and brain . In some cases birth defects .
Eating tuna
In Japan , 121 people were poisoned after eating tuna fish which
was contaminated with mercury . 46 people out of 121 died . Their
symptoms were ,

5. Lack of coordination
Paralysis
Difficulty in swallowing
Brain damage ..