1. MARINE POLLUTION:
Heavy Metals
M. Nadeem Ashraf

2. What is marine pollution?
According to the UN Group of Experts on the
Scientific Aspects of Marine Pollution
(GESAMP):
Marine pollution is the introduction by man,
directly or indirectly, of substances or energy to
the marine environment resulting in deleterious
effects such as:
hazards to human health;
hindrance of marine activities, including fishing;
impairment of the quality for the use of seawater,
and reduction of amenities.

3. What is contamination?
Contamination is caused when an input
from human activities causes the increase
of a substance in seawater, sediments, or
organisms above the natural background
level for that area and for those
organisms.

4. Measuring contamination?
Contamination is usually measured as
parts (of pollutant) per million (ppm) = µg.g-1
or parts per billion (ppb) = ng.g-1 = µg.kg-1
it is measured as “wet weight”
(e.g. contamination in moist water containing tissues)
or as “dry weight”
(e.g. contamination in dehydrated tissues)
as water content can vary a lot
– dry weight is a better measure

5. Heavy metal pollution
High atomic weight metals (mercury, lead etc.)
Sometimes the term trace elements is used to
include non-metal and lower atomic weight
elements
Many of these elements are essential to the
body in very low concentrations:
 Iron – essential for hemoglobin
 Copper - essential for hemocyanin (in invertebrates)
 Cobalt – in vitamin B 12
 Zinc – essential component of many enzymes

6. Heavy metal pollution
But in high concentrations these can be
toxic.
e.g. one asprin 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

7. Clark (2001)
Toxicity of metals can vary according the their valency
(e.g. 2+ or 3+) and their combination with other elements
LC50: contaminant concentration level required for 50% of the test species to die

8. Bioaccumulation
Pollutants like heavy metals are CONSERVATIVE
pollutants – i.e. they aren’t broken down by bacteria etc
and are effectively permanent
Most plants and animals can regulate their metal
content to a certain point – but metals that can’t
be excreted build up in an organism over its
lifetime
= BIOACCUMULATION

9. Biomagnification
Animals feeding on bioaccumulators take in a higher
level of contaminants, which bioaccumulate within
themselves
Those animals feeding on them gain even higher
inputs of contaminants, and bioaccumulate even
greater concentrations
and so on… with animals at the highest trophic
level obtaining highest concentrations
= BIOMAGNIFICATION
i.e. long-living, top predators bioaccumulate and
biomagnify the highest contaminant levels

11. Sources of heavy metal pollution
ATMOSPHERIC
 Forest fires
 Volcanic activity
 Dust particles
 Anthropogenic emissions
 coal fired power stations
 car exhausts

12. Clark (2001)

13. Sources of heavy metal pollution
ATMOSPHERIC
Metals can be transferred by the atmosphere in gas or
particle form (aerosol)
 Particles can fall from the atmosphere onto the land or sea =
dry deposition
 Also precipitation can carry particles or dissolved gases =
wet deposition
 Gaseous state elements (Boron, Mercury, Selenium) can also dissolve
at the surface of water bodies (gaseous exchange)
 Bubbles breaking the surface of the sea can release salt
particles containing metals
– can travels from sea to atmosphere as well as atmosphere to sea

14. Clark (2001)

15. Sources of heavy metal pollution
RIVERS
 Erosion of rocks containing metals
 Surface runoff sweeps up naturally formed
and anthropogenic metal particles
Metals often bind with sediments and are
deposited on the seabed
– but these can enter the marine environment
again is there is:
 Dredging
 Trawling
 Severe weather

16. Sources of heavy metal pollution
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

18. Clark (2001)

19. Clark (2001)

20. Islam & Tanaka (2004).

21. MERCURY (Hg)

23. Toxic effects of mercury
 Mercury can cause neurological damage,
immune system suppression and can
cause fetal abnormalities in mammals
[Clarkson (1987); von Burg and Greenwood (1991) ]
 In humans it has been associated with
various neurological effects, abnormal
development and heart damage
[Guallar et al., (2002); Clarkson et al., (2003); Murata et al. (2004); Grandjean et al. (2004) ]

24. Mercury toxicity
 In human adults mercury toxicity symptoms include:
 Visual field constriction
 Behavioral changes, memory loss, headaches
 Tremor, loss of fine motor control, spasticity
 Hair loss
 If fetuses / infants are exposed to mercury:
•Mental retardation
•Seizures
•Cerebral palsy
•Blindness and deafness
•Disturbances of swallowing, sucking, and speech
•Hypertonia - muscle rigidity
[Clarkson et al., (2003)]

25. Toxic effects of mercury
 Mercury in the marine environment
identified as a health risk for humans –
Minamata disease
 In 1952 a factory in Minamata Japan was
using mercury as a catalyst
– mercury washed into bay
 In 1953 fishermen and farmers showed
symptoms – neurological damage and
fetal deformity etc.

26. Minamata disease
 Disease diagnosed in 1956
– linked to fish consumption
 1957 fishing banned in area
 1959 – mercury identified as cause
1960 source identified

– factory effluent
 2000 cases – 41 deaths and 700 permanent disabilities
fish: 10-55 ppm (dry weight); bivalves 10-39 ppp (dry weight)

27. Toxic effects of mercury
 In the US an estimated 650,000 newborns a
year are at risk from developmental and
neurological damage due mercury [Mahaffey (2004)]
 The source of this mercury is
contaminated seafood
 Around the world seafood with mercury
levels over 0.5 to 1.0 ppm are considered
unsafe for human consumption

28. Mercury in fish
 Most fish species have mercury levels of
approximately 0.15 ppm in muscle tissue
 However cod have been found with levels of
1.29 ppm in Sweden and Denmark
 Tuna highly contaminated [Adams (2004)]
 Blackfin tuna (Thunnus atlanticus) up to 2ppm
 81% more contaminated than 0.5 ppm health regulation
 Little tunny (Euthynnus alletterus) up to 3.4ppm
 75% more contaminated than 0.5 ppm health regulation
 Recreational fish - Red drum (Scaenops ocellatus) also
contaminated: up to 3.6 ppm; 95% >0.5 ppm health limit
[Adams & Onorato (2004)]

29. Adams (2004)
Yellowfin tuna are pelagic and have lower levels of Hg.
Blackfin tuna are primarily near-shore species and show elevated Hg concentrations

30. Mercury in marine mammals
 As long-lived top predators marine mammals
accumulate very high concentrations of mercury
 Indo-Pacific humpback dolphins (Sousa chinensis)
900 ppm dry weight [Parsons (1999)]
 Striped dolphins (Stenella coeruleoalba)
485 ppm wet weight (~ 1600 ppm dry weight)
[Honda et al., (1983)]
 Bottlenose dolphins (Tursiops truncatus)
13,156 ppm dry weight [Leonzio et al., (1992)]

31. Mercury in marine mammals
 Toxic effects reported in marine mammals
include:
 Lesions in the liver and other tissues; decrease nutritional
state and fatty degeneration
[Rawson et al., (1993); Siebert et al., (1995)]
 High mercury (and other heavy metal) levels
have also been associated with disease
-induced mortality
i.e. mercury may damage the immune
system [Bennett et al., (2001)]

32. Mercury in whale meat
Recent research has
shown that cetacean
meat being sold in
Japan for human
consumption had
extremely high levels
of mercury
Mean contamination levels in cetacean red meat were 22 and 18 times
higher than levels permitted by the Japanese government for total mercury
(0.4 ppm)
Levels were exceeded by up to 200x
Mercury levels in boiled liver were even higher: 1,980 ppm (wet weight).
Rats fed contaminated meat showed signs of kidney abnormalities after a
single dose Endo et al., (2002; 2003a; 2003b; 2004)

33. Mercury in whale meat
Another study in the
Faeroe islands looked
at the effects on the
population of eating
contaminated long-
finned pilot whale
meat
Effects linked with mercury contamination included mental retardation,
neurological abnormalities and brain stem damage in children
Abnormal heart activity also linked to mercury contamination
Prenatal exposure to mercury was believed to be causing irreversible
neurological damage
[ Murata et al. (2004); Grandjean et al. (2004) ]

34. Imputs of Mercury
6000-7500 tons a year

35. Clark (2001)

36. U.S. Anthropogenic Mercury
Emissions
~ 158 Metric Tons
Sources
 87% combustion MercuryEmissions
Mercury emissions
 33% coal fired power
 19% burning municipal Global
6%
waste US
 10% burning medical
waste
Mercury production
 10% manufacturing Mercury Production 1996
 3% all other sources
15%
• 2/3 deposited outside US
•~53 tons deposited inside US Data & Images:
Moore (2002)
+ 35 tons deposited in US from outside sources

37. Mercury trends
 Over past 100 years there’s been a 20 x
increase in the deposition of mercury
 70% of this mercury has been from
anthropogenic sources
 Over past 10 years – deposition has declined
– BUT deposition rate is still 11x higher than in
the pre-industrial era
Schuster (2002)

38. Schuster (2002)

39. CONTROVERSIAL: Mercury and US Policy
 During the Clinton Administration the Environmental
Protection Agency conducted research on the impacts of
mercury and the role of coal-fired power plants in mercury
emissions.
 The EPA introduced a plan in which mercury emissions from
coal-fired power plants would be reduced by 90% by 2008.
 The Bush Administration altered these plans: emissions
would be lowered by only 70% by 2018.
“Under the Bush plan, you will have seven times more mercury released
into the waters than if we just simply followed the Clean Air Act as it is
written today. There will be no overall reduction in mercury. Every other
major source of pollution has been subject to the requirements of the
Clean Air Act, until now. The Bush Administration has simply decided
that the coal-fired power industry will be exempt.”
Felice Stradler of the National Wildlife Federation
 Several states decided the Bush Administration plan is insufficient and
are attempting to follow the original Clinton Administration plan is too
lenient and they will follow the original.

40. 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

41. CADMIUM (Cd)
TOXIC EFFECTS
High cadmium levels can lead to:
 depressed growth,
 kidney damage,
 cardiac enlargement,
 hypertension,
 foetal deformity, [Kostial (1986); Stoeppler (1991)]
 cancer
In humans cadmium concentrations above 200-400
ppm in kidney tissue can lead to renal damage
Piotrowski & Coleman (1980)

42. Kidney dysfunction has
been reported in
cetaceans when liver
concentrations of
cadmium exceed 20
ppm wet weight.
Fujise et al. (1988)

43. 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
(up to 4.3 ppm wet weight ~ 14 ppm dry weight) [Law et al., (1992)]

44. LEAD (Pb)
 The toxic effects of lead include:
 anaemia,
 kidney damage,
 hypertension,
 cardiac disease,
 Immune system suppression (antibody inhibition)
neurological damage
Quaterman (1986)

46. OTHER HEAVY METALS OF
CONCERN
 Aluminium
 Arsenic
 Copper
 chromium
 Iron
 Silver
 Nickel
 Zinc – linked with decreasing health in porpoises
(Das et al., 2004)
 Tin….

47. Superfund site in Tacoma: a copper smelter deposited slag containing lead
and arsenic along the shoreline from 1890 to 1985.
In 1980 (Carter Administration) the Superfund system was
established to cleanup old waste sites that may pose an
environmental or human health threat – including heavy metal
contaminated sites
- over 900 sites have been cleaned to date.

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SLIDE IMAGES:
Moore, C. 2002. Historical background of mercury in the environment.
Paper presented at the Mercury Forum, Mercury Forum, May 20-21, 2002, Mobile, TX.
<http://www.masgc.org/mercury/ppt/Moore-ppt_files/frame.htm>