4.4 water pollution

water pollution

contamination of water bodies by harmful substances making them unsafe for humans, wildlife, ecosystems

types of pollution

1. chemical (pesticides, heavy metals)

2. microbial (pathogens)

major sources of water pollution

1. sewage

2. agricultural run-off

3. industrial effluent

4. urban run-off

5. solid waste disposal

6. oil spills

sewage

untreated sewages introduce pathogens , organic matter into water bodies

→ leads to eutrophication and disease outbreaks

agricultural run-off

fertilisers and pesticides wash into rivers, lakes

causes:

• eutrophication

• biodiversity loss

industrial effluent

factories discharge heavy metals and PCBs into water these pollutants bioaccumulate in food chains.

urban-run off

rainwater (gravity movement) washes pollutants from roads and cities into waterways (oils and grease, road salts, heavy metals)

solid waste disposal

plastics and other waste clog waterways

• breaks down into micro plastics which enter food chains through the primary producer

oil spills

LONG TERM IMPACT on fisheries and tourism

coast marine life reducing oxygen levels devastating ecosystems

Harm caused by ocean plastic

1. ingestion - blockages, starvation, malnutrition

2. entanglement - injury, restricted movement

3. coral reef damage - prevent growth

to humans:

• microplastics enter food chain

• chemical contaminates

Impacts of water pollution

1. eutrophication

2. hypoxia - decomposition of algae depletes oxygen creating dead zones

3. bioaccumulation and biomagnification affect top predators, humans

4. spreads diseases (cholera)

5. reduce fish stocks

6. increases costs for water treatment and damages tourism

bioaccumulation

buildup of harmful chemicals in an organism over time

biomagnification

increase of harmful chemicals as they move up the food chain

how do plastics accumulate in ocean gyres

Plastics are carried by ocean currents and become trapped in gyres—large circular current systems in major ocean basins.

how do micro plastics enter food chain?

They are ingested by plankton, fish, and shellfish, entering the food chain at its lowest levels

• bioaccumulation

• biomagnification

managing plastic pollution

1. bans on single use plastic

2. eco-friendly alternatives

3. extended producer responsibility

4. ocean cleanup projects

5. microplastic filtration technology

6. public awareness and policy action