MARINE POLLUTION:Heavy Metals BIO 508-001 EVPP 505-001
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
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
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
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 ppmdry weight[Parsons (1999)] • Striped dolphins (Stenella coeruleoalba) 485 ppmwet weight (~ 1600 ppmdry weight)[Honda et al., (1983)] • Bottlenose dolphins (Tursiops truncatus) 13,156ppmdry weight[Leonzioet 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
U.S. Anthropogenic Mercury Emissions~ 158 Metric Tons Sources • 87% combustion • 33% coal fired power • 19% burning municipal waste • 10% burning medical waste • 10% manufacturing • 3% all other sources Mercury emissions 6% Mercury production 15% • 2/3 deposited outside US • ~53 tons deposited inside US • + 35 tons deposited in US from outside sources Data & Images: Moore (2002)
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)
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, • cancer [Kostial (1986); Stoeppler (1991)] • 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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