This document discusses heavy metal uptake by organisms. It defines heavy metals as relatively dense, toxic metals found naturally in small amounts in soil, water and air. Some heavy metals like zinc and copper are essential nutrients in small amounts but become toxic at higher concentrations. Heavy metals can accumulate in organisms and biomagnify up the food chain. Specific heavy metals discussed include mercury, cadmium, chromium, lead and arsenic. For each, sources, health effects on humans and environments, and control/remediation strategies are summarized. Measurement methods for heavy metals include atomic absorption spectrophotometry and x-ray fluorescence.

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