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HEAVY METAL POLLUTION

M.MOHAMMED KISHORE (10E621)

B.MUTHUKANNAN (10E622)

P.MUTHUKUMARAN (10E623)

B.NAVEEN KUMAR (10E624)

M.NEELABHARATHY (10E625)

S.SABARINATHAN (11E910)

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The term heavy metal refers to any metallic chemicalelement that has a relatively high density and is toxic or

poisonous at low concentrations.High atomic weight metals (mercury, lead etc.)

Sometimes the term trace elements is usedto include non-metal and lower atomic weight

elements Many of these elements are essential to thebody in very low concentrations:

Iron essential for hemoglobin

Copper - essential for hemocyanin (ininvertebrates)

Cobalt in vitamin B12Zinc essential component of many enzymes

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But in high concentrations these can be toxic.

e.g. one aspirin tablet is a useful medicine

but 100 tablets are lethal

Some heavy metals have no essential function in the

body (e.g. mercury, lead) and any concentrations can be

harmful

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are natural components of the Earth's crust they cannot be degraded or destroyed to a small extent they enter our bodies via food,

drinking water and air

as trace elements, some heavy metals (e.g. copper, selenium, zinc) are essential to maintain the

metabolism of the human body however, at higher concentrations they can lead to

poisoning

heavy metal poisoning could result, for instance, fromdrinking-water contamination (e.g. lead pipes), highambient air concentrations near emission sources, orintake via the food chain

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SOURCES

Mercury

Lead

chromium,

Cadmium

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RIVERS

Erosion of rocks containing metals

Surface runoff sweeps up naturally formed and

anthropogenic metal particlesMetals often bind with sediments and are deposited onthe seabed

but these can enter the marine environment again is

there is:Dredging

Trawling

SOURCES

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GROUNDWATER SEEPAGE

Dissolved substances are carried via ground

water movement contamination in soil may

be picked up by the moving waters

DELIBERATE DISCHARGE

Contaminated waste dumping

Industrial discharges

Sewage

SOURCES

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MERCURY EFFECTS

Visual field constriction

Behavioral changes, memory loss, headaches

Tremor, loss of fine motor control, spasticity

Hair loss

In human adults mercury toxicity symptoms include:

If foetuses / infants are exposed to mercury:

Mental retardation

Seizures

Cerebral palsy

Blindness and deafness

Disturbances of swallowing, sucking, and speech

Hypertonic - muscle rigidity

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INPUTS OF MERCURY

6000-7500 tons a year

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CADMIUM (Cd)

Cadmium was used in:

Electroplating, solder and as a pigment for plastics But less frequently now due to health concerns

Main sources of current production:

By product of zinc mining

Nickel-Cadmium battery production

Other sources:

Burning coal (0.25-0.5 ppm) and oil (0.3ppm)

Wearing down of car tyres (20-90 ppm)

Corrosion of galvanised metal (impurity: 0.2% Cd)

Phosphate fertilisers (phosphate rock 100 ppm Cd)

Sewage sludge (30 ppm)

Input of Cadmium into oceans: 8000 tons/year - 50%

anthropogenic

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CADMIUM (Cd)

TOXIC EFFECTSHigh cadmium levels can lead to:

depressed growth,

kidney damage,

cardiac enlargement, hypertension,

foetal deformity,

cancer

In humans cadmium concentrations above 200-400 ppm in

kidney tissue can lead to renal damage

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Kidney dysfunction has

been reported in

cetaceans when liver

concentrations of

cadmium exceed 20

ppm wet weight.

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LEAD (Pb)

Lead is used in:

Battery casings, pipes, sheets etc

43 million tons produced a year

10% of lead production is for lead-based additives for

gas (e.g. tetraethyl lead)

High levels of lead have been found in marine life near areas

of high car density

- e.g. 10 ppm in fish caught 300 miles off California coast - High levels of lead in UK cetaceans were attributed to

lead additives in fuel

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The toxic effects of lead include:

anaemia,

kidney damage,

hypertension,

cardiac disease,

Immune system suppression (antibody inhibition)

neurological damage

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Aluminium

Arsenic

Copper

chromium

Iron

Silver

Nickel

Zinc linked with decreasing health in porpoises

OTHER HEAVY METALS OF

CONCERN