4. Metals
A metal is a solid material (an
element, compound, or alloy )
that is typically hard, opaque,
shiny and features good electrical
and thermal conductivity.
6. Heavy
metals
The term heavy metal refers to
any metallic chemical element
that has a relatively high
density and is toxic or poisonous
at low concentrations.
7. Heavy
metals
Macro-nutrient
elements
• Cobalt(Co), copper(Cu), Zinc(Zn), iron(Fe)
Micro-nutrient
elements
• Copper(Cu), nickel(Ni), chromium(Cr), iron(Fe)
Highly toxic elements
• Cadmium(Cd), lead(Pb), silver(Ag), mercury(Hg)
Precious elements
Precious elements
• platinum, silver(Ag), gold
11. Minamata
disaster
•
1932Minamata
Sewage containing mercury is released by Chisso's chemicals works
into Minimata Bay in Japan. The mercury accumulates in sea
creatures, leading eventually to mercury poisoning in the population.
•
1952Minamata Syndrome
In 1952, the first incidents of mercury poisoning appear in the
population of Minimata Bay in Japan, caused by consumption of fish
polluted with mercury, bringing over 500 fatalities. Since then, Japan
has had the strictest environmental laws in the industrialised world.
13. Sandoz
chemical
spill
The Sandoz chemical spill was a major
environmental disaster on November 1,
1986 caused by a fire at a chemical factory
Sandoz near Basel, Switzerland, sending
tons of toxic chemicals into the nearby river
Rhine and turning it red. The chemicals
caused a massive mortality of wildlife
downstream, killing among other things a
large proportion of the European
eel population in the Rhine, although the
situation subsequently recovered within a
couple of years. The stored chemicals
included, beside urea and fluorescent
dye, organophosphate insecticides,mercury
compounds and organochlorides.
14. Spill mining
wastewater
Spain 1998
In april 1998 a sudden burst in
a chemical reservoir send a
stream of water contaminated
by, zinc, lead and cadmium
into the Guadiamar river
system.
Experts estimate that Europe's
largest bird sanctuary, as well
as Spain's agriculture and
fisheries, will suffer
permanent damage from the
pollution
15. Itai-itai
itai-itai disease was the documented case
of mass cadmium poisoning in Toyama
Prefecture, Japan starting around 1912.
The cadmium poisoning caused softening
of the bones and kidney failure. The
disease is named for the severe pains
caused in the joints and spine.
The cadmium was released into rivers by
mining companies in the mountains. The
mining companies were successfully sued
for the damage. Itai-itai disease is known as
one of the Four Big Pollution Disease of
Japan
The term "itai-itai disease" was coined by
locals
16.
17. Respiratory Absorption
a. Metal may be inhaled as vapor or aerosol (fume or dust particulate) Fume or vapor
of some metals & compound are readily absorbed in from alveolar space
(cadmium, mercury, tetraethyl lead)
b. Large particles trapped in upper respiratory tract, cleared by mucociliary transport
to pharynx and swallowed (equivalent to oral exposure)
c. Small particles may reach alveolar/gas exchange. Water soluble metal aerosols are
rapidly absorbed from alveoli into the blood
18. Gastrointestinal Absorption
1)Metal may introduce into GI tract through food, water, mucociliary
clearance.
2)Metal are absorbed into the cells lining the intestinal tract by:
Passive or facilitated diffusion
Specific transport process
Pinocytosis
It depends on many factors
Solubility of metal in fluids of the intestinal tract
Chemical forms of metal (lipid soluble methyl mercury is completely
absorbed compare to inorganic mercury – poorly absorbed)
Presence and composition of other materials in GI tract
Composition for absorption sites between similar metals (zinc &
cadmium or calcium & lead)
Physiological state of the person exposed (Vitamin D enhance the
absorption of lead)
19. Kidney - Important route of excretion
1)
Metals in blood plasma are bound to plasma
proteins and amino acids
2) Metals bound to low molecular weight
proteins and amino acids are filtered in
glomerulous into fluid of the renal tubule
3) Some metals (Cd & Zn) are effectively
resorbed by tubular epithelia before they reach
the urinary bladder where very little resorption
occur.
20. Excretion
Enterohepatic Circulation
Absorbed metal may also excreted into intestinal tract in bile,
pancreatic secretion or saliva
Minor Pathways
Hair (Hg, Zn, Cu and As)
Nails
Saliva
Perspiration
Exhaled air
Lactation
Exfoliation of skin
30. Phytoremediation
Phytoremediation is the use of plants to clean up a contamination from soils,
sediments, and water. This technology is environmental friendly and potentially
costeffective. Plants with exceptional metal-accumulating capacity are known as
hyperaccumulator plants . Phytoremediation takes the advantage of the unique
and selective uptake capabilities of plant root systems, together with the
translocation, bioaccumulation, and contaminant degradation abilities of the
entire plant body.
31. Mechanism of heavy metal uptake by plants through phytoremediation technology
1) Phytostabilization
2) Rhizodegradation
3) Phytodegradation
4) Phytoextraction
5) Phytovolatilization
