1. Topic:
Metals uptake by
organisms
By
Maryum Atique
M. Phill chemistry
University of
Agricylture, FSD

2. 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.

3. Properties
• 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, from
drinking-water contamination (e.g. lead pipes), high
ambient air concentrations near emission sources, or
intake via the food chain

4. Bioaccumulation
• Bioaccumulation is the “build-up of
chemicals or heavy metals in living
organisms”.
• The chemical accumulates because it
does not break down easily (decomposers
can’t break them down)
• The chemicals get stored in fat-cells of
organisms and can cause serious
problems...

6. Mercury
Hg
• Mercury is the only common metal which
is liquid at ordinary temperatures. It rarely
occurs free in nature and is found mainly
in cinnabar ore (HgS) in Spain and Italy.
• It alloys easily with many metals, such as
gold, silver, and tin - these alloys are
called
amalgams.
Its
ease
in
amalgamating with gold is used in the
recovery of gold from its ores.

7. •
•
•
•
Health effects of mercury
Disruption of the nervous system
Damage to brain functions
DNA damage and chromosomal damage
Allergic reactions, resulting in skin rashes,
tiredness and headaches

8. • Acidic surface waters can contain significant
amounts of mercury
• When the pH values are between five and
seven, themercury concentrations in the water
will increase due to mobilisation of mercury in
the ground
• Once mercury has reached surface waters or
soils microorganisms can convert it to methyl
mercury, a substance that can be absorbed
quickly by most organisms and is known to
cause nerve damage

10. Cadmium
Cd

11. Sources of Cadmium
 Cadmium is used as an electrode in
“nicad” batteries
 Cadmium is used as a pigment in
paints(yellow color)
 It is also used in photovoltaic devices and
in TV screens
 Cigarette smoke
 Fertilizers and pesticides
Note: The greatest proportion of our
exposure to cadmium comes from our
food supply- seafood, organ meats,
particularly kidneys, and also from
potatoes, rice, and other grains.

12. HEALTH EFFECTS
• Human uptake of cadmium takes
place mainly through food
• Diarrhoea, stomach pains and
severe vomiting
• Bone fracture
• Damage to the central nervous
system
• Damage to the immune system
• Psychological disorders
• Possibly DNA damage or cancer
development

13. Environmental effects of cadmium
• Cadmium can be transported over great
distances when it is absorbed by sludge
and can pollute surface waters as well
as soils
• Cadmium strongly adsorbs to organic
matter in soil
• When cadmium is present in soils it can
be extremely dangerous, as the uptake
through food will increase
• Soils that are acidified enhance the
cadmium uptake by plants
• This is a potential danger to the animals
that are dependent upon the plants for
survival – Cadmium can accumulate in
their bodies, especially when they eat
multiple plants. e. g: cow

14. Chromium - Cr
• Chromium(III) is an essential nutrient for
humans and shortages may cause heart
conditions, disruptions of metabolisms and
diabetes
• But the uptake of too much chromium(III)
can cause health effects as well, for
instance skin rashes

15. HEALTH EFFECTS
• When it is a compound in leather products, it can
cause allergic reactions, such as skin rash
• After breathing it in, chromium(VI) can cause
nose irritations and nosebleeds
• Upset stomachs and ulcers
• Respiratory problems
• Weakened immune system
• Kidney and liver damage
• Alteration of genetic material
• Lung cancer
• Death

16. Environmental effects of chromium
• Most of the chromium in air will eventually settle
and end up in waters or soils
• Chromium in soils strongly attaches to soil
particles and as a result it will not move towards
groundwater
• In water chromium will absorb on sediment and
become immobile

17. Lead - Pb
• Foods such as fruit, vegetables, meats, grains,
seafood, soft drinks and wine may contain
significant amounts of lead
• Cigarette smoke also contains small amounts of
lead

18. Lead sources
•
•
•
•
application of lead in gasoline
fuel combustion
industrial processes
solid waste combustion

19. Health effects of lead
• Disruption of the biosynthesis of
haemoglobin and anemia
• A rise in blood pressure
• Kidney damage
• Disruption of nervous systems
• Brain damage
• Diminished learning abilities of children
• Behavioural disruptions of children, such
as aggression, impulsive behaviour and
hyperactivity

20. Environmental effects of lead
• Soil functions are disturbed by lead
intervention, especially near highways and
farmlands, where extreme concentrations
may be present
• Also soil organisms are suffered from lead
poisoning

21. Arsenic
• Arsenic oxides were the
common poisons used for
murder and suicide from roman
times through to the middle
ages
• Arsenic compounds were used
widely as pesticides before the
organic chemicals era
• Arsenic is very much similar to
phosphorous

22. Sources of Arsenic
 Pesticides
 Mining, smelting of gold, lead, copper
and nickel
 Production of iron and steel
 Combustion of coal
 Leachate from abandoned gold mines
 Used as a wood preservative
 Herbicides
 Tobacco smoke
 Wallpaper paste and pigments in
wallpaper

23. Health effects
 Birth defects
 Carcinogen:
Lung cancer results from the inhalation of
arsenic and probably also from its ingestion. Skin
and liver cancer, and perhaps cancers of the
bladder and kidneys, arise from ingested arsenic
 Gastrointestinal damage
 Severe vomiting
 Diarrhea
 Death
•Causes arsenic keratosis
of skin

24. Arsenic in drinking water in
US

25. General sources of heavy metals in
residential houses
• Infiltration from outside, along with
the dust carried on shoes and
clothes
• Indoor sources include old-lead
and latex based paints, domestic
water supply, burning of wood,
and tobacco smoke
• Pesticides and fungicides are
major sources of arsenic and
mercury indoors

26. Methods for measurement of trace
metals
 Most common method of collecting particulate matter is
through filters
 Identification and concentration of individual trace
metals like lead, cadmium, arsenic, mercury and
chromium is determined by
 Atomic absorption
spectrophotometer
 X-ray fluorescence
 Atomic absorption spectrophotometry is a
destructive method and requires at least 1 to 2
ml of solution
 X-ray fluorescence is a nondestructive method
and works independent of the chemical state of the
sample.

27. Control strategies

28. Control methods
• Periodic vacuuming of the house can be effective
in removal of these pollutants
• Replacement of wood-burning by an equivalent
gas or electrical appliance
• Removal of old lead and mercury-based paints
• The effective method for removal of mercury
vapors is by the use of packed bed of absorbents
• Gold-coated denuder can also be used for the
removal of mercury from air