Water pollution

• Water covers over 70% of the Earth's surface and is a very important resource for people and the environment.

• Water pollution affects drinking water in groundwater, rivers and lakes all over the world. This consequently harms human health and the natural environment.

• Water pollution also harms marine ecology inc. fishstocks, sea-birds etc.

http://www.water-pollution.org.uk/

Source: http://ga.water.usgs.gov/edu/earthwherewater.html

Source: http://ga.water.usgs.gov/edu/earthwherewater.html

Where does water pollution come from?

• Point source, directly into water, e.g. oil spill from a ship •Nonpoint source, e.g.

indirectly into water, e.g. fertiliser run-off from farms

Many activities result in water pollution

• Mining• Agriculture – e.g. agro-chemicals; manure• Household cleaning, e.g. phosphates• Sediment, e.g. Land reclamation; erosion• Industrial waste• Oil spillage• Dumping • Sewage• Air pollution settling in water, e.g. mercury (Hg)• Radioactive pollution

Mining

• Exposes heavy metals and sulphur compounds which were previously locked underground

• Discharges contaminated effluent into water• Relies on large quantities of water to process ore• Seepage from waste – leaches aquifers,

contaminating underground water• Each tonne of copper extracted results in 99

tonnes of waste material

Exposure of sulphur in rocks reacts with water and oxygen to form sulphuric acid. Acid is carried off the mine-site by rainwater or surface drainage and deposited into nearby water bodies inc. groundwater. This severely degrades water quality, and can kill aquatic lifeand make water virtually unusable.

Heavy metals from industrial processes can accumulate in nearby lakes and rivers. These are toxic to marine life such as fish and shellfish, and subsequently to the humans who eat them. Heavy metals can slow development; result in birth defects and some are carcinogenic.

Agriculture

• Fertilisers used to increase plant growth contain nitrates and phosphates

• These nutrients end up in water, causing an overgrowth of algae. This is known as eutrophication or algal blooms.-Algae blocks light to deeper waters-As algae dies, its decomposition depletes oxygen from water-Reduces life in water (fish and plants)

Red tides – overgrowth of phytoplankton

Algal bloom / eutrophication

The Salton Sea, California. Massive fish deaths are common here due to poor agricultural

practices (supported by US legislation).

Household cleaners & personal products

• Wash down drain into water system• Nonylphenol (in detergent) disrupts fish

reproduction• Phosphates cause eutrophication

Agriculture-pesticides

• Pesticides are another product resulting in water pollution

• Pesticides are designed to kill unwanted bugs and vermin• They contain hazardous substances• Pesticides in water end up in the human body• Many pesticides are very long-living, and accumulate in

the body• Pesticides cause many health problems inc. hormone

disruption, immuno-suppression, behavioural disorders, infertility, cancer

Sediment• Soil, clay, sand, silt and dead organic (plant &

animal) material can end up in water• These particles make the water murky (unclear).

This limits photosynthesis of water plants and makes it difficult for fish to find food.

• Sediment contaminates drinking water• Sediment can carry nutrients thus causing algal

blooms• Sediment can kill fish (by blocking gills) and

disrupt reproduction

What increases sediment in water?

• Land erosion (from deforestation)• Construction activities• Land reclamation• Dredging• Rain• Stormwater• Hosing of hard surfaces

Industrial processes• By-products of industry such as radioactive

waste, heavy metals, dyes• Much hazardous waste is injected into deep

bedrock (beneath water table). Some of these pollutants have found their way into the underground water

• Discharges (cooling waters) from power plants and factories warm the water, causing fish deaths & coral bleaching

Healthy coral

Bleached coral – caused by sediment &/or increased sea temeperatures

Oil• Oceans are polluted by oil on a daily basis from oil spills, routine

shipping, run-offs and dumping. • Oil spills make up about 12% of the oil that enters the ocean. The rest

come from shipping travel, drains and dumping. • An oil spill from a tanker is a severe problem because there is such a

huge quantity of oil being spilt into one place. • Oil spills cause a very localised problem but can be catastrophic to

local marine wildlife such as fish, birds and sea otters. • Oil cannot dissolve in water and forms a thick sludge in the water.

This suffocates fish, gets caught in the feathers of marine birds stopping them from flying and blocks light from photosynthetic aquatic plants.

• Oil persists for a long time.

Dumping

• http://www.youtube.com/watch?v=8a4S23uXIcM

• Plastic soup - Moving up the food chain• Animals mistake rubbish for food• Marine animals often die after becoming

entangled in fishing nets and other discarded rubbish

• Street litter often ends up in the ocean via stormwater drains

Dumping at sea

• Dumping of litter in the sea can cause huge problems. Plastic is eaten by marine animals and may result in death.

• Cardboard – Takes 2 weeks to degrade. • Newspaper – Takes 6 weeks to degrade. • Photodegradable packaging – Takes 6 weeks to degrade. • Foam – Takes 50 years to degrade. • Styrofoam – Takes 80 years to degrade. • Aluminium – Takes 200 years to degrade. • Plastic packaging – Takes 400 years to degrade. • Glass – It takes so long to degrade that we don’t know the

exact time.

Sewage

• Untreated sewage causes many problems inc.:-Rashes-Gastroenteritis-Hepatitis-Ear infections-Pink eye-Algal blooms

Air pollution

• Airborne mercury (Hg) from fossil fuel burning and chlorine and cement industries settles in water

• This Hg accumulates in fish –the bigger the fish, the greater the amount

• Pregnant women and young children are most at risk from this

Radioactive pollution

• This is a hazardous material and all handling and disposal must be strictly compliant with government legislation

• Radioactive waste is very long-lived and needs “babysitting” for many millennia

Tips for everyday citizens•Conserve water •Be careful about what you throw down your sink or toilet. •Use environmentally household products, such as washing powder, household cleaning agents and toiletries. •Take great care not to overuse pesticides and fertilisers. •Don't throw litter onto streets or into rivers, lakes or oceans. •Limit your purchase of over-packaged items.•Become more aware of the overall impact of the products you buy

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