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11-Pollution _Heavy metals in Fish_

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					MARINE POLLUTION:
   Heavy Metals
     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.
    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.
   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
           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 B12
   Zinc – essential component of many enzymes
       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
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
            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
           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
 Sources of heavy metal pollution
ATMOSPHERIC
 Forest fires
 Volcanic activity
 Dust particles
 Anthropogenic emissions
   coal fired power stations
   car exhausts
Clark (2001)
  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
Clark (2001)
 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
  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
Clark (2001)
Clark (2001)
Islam & Tanaka (2004).
MERCURY (Hg)
            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) ]
                   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)]
        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.
                   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)
        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
                      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)]
Adams (2004)




Yellowfin tuna are pelagic and have lower levels of Hg.
Blackfin tuna are primarily near-shore species and show elevated Hg concentrations
     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)]
     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)]
                   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)
                  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) ]
Imputs of Mercury




 6000-7500 tons a year
Clark (2001)
      U.S. Anthropogenic Mercury
               Emissions
           ~ 158 Metric Tons
 Sources
  87% combustion                      Mercury emissions
                                      MercuryEmissions
           33% coal fired power
           19% burning municipal                             Global
            waste
                                         6%
                                                              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
           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)
Schuster (2002)
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.
                      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
                 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)
Kidney dysfunction has
been reported in
cetaceans when liver
concentrations of
cadmium exceed 20
ppm wet weight.




             Fujise et al. (1988)
                            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)]
                   LEAD (Pb)
   The toxic effects of lead include:
      anaemia,
     kidney damage,
     hypertension,
     cardiac disease,
     Immune system suppression (antibody inhibition)
      neurological damage
                                    Quaterman (1986)
OTHER HEAVY METALS OF
      CONCERN
   Aluminium
   Arsenic
   Copper
   chromium
   Iron
   Silver
   Nickel
   Zinc – linked with decreasing health in porpoises
                                                        (Das et al., 2004)
   Tin….
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>

				
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