(a) Effects on the environment - reduction of biodiversity as the world population steadily rises

People in poorer underdeveloped countries, unsurprisingly, want the same material standard of living as people living in richer more developed countries.

So consumer demand and rising population are presenting us, and the rest of nature, with rather a lot of issues to try and sort out as we put increasing pressure on the environment by our methods of land use and extracting minerals (coal, oil, gas , metals) that we want to survive and increase our standard of living..

When the world's population was smaller, the problems were not as great and the effects of human activity were much more localised.

 

The graphs shows the acceleration of the world's population and their corresponding energy use.

Surely you would expect a similar acceleration of waste from domestic and industrial human activity?

AND, much of this is having a negative effect on the environment of our planet.

There is an increasing demand for a higher standard of living ranging from greater quality of food, consumer goods to transport and recreation facilities.

So we need more raw materials from the natural resources of the land and sea to sustain our way of life - food and consumer goods etc.

But, we also need more energy (see 2nd graph above) to sustain our desired higher standard of living - so we are continuing to exploit coal, oil and gas reserves - despite an increasing use of renewable energy resources like wind turbines, solar power and hydroelectric power.

So, overall, we are taking increasingly larger quantities of many things from the Earth's resources at an ever increasing rate!

If we continue to extract and consume these natural resources at an even faster rate, we might just run out of some important resources and be unable to meet the demands of an ever increasing world population.

 

All of this human activity is creating a lot of waste and spreading pollution locally and around the world.

e.g.  pollution of 'local' land, lakes, streams and river systems from overuse of fertilisers, sewage-human effluent, factory effluent,

and now plastic waste is found all over our oceans! Pollution has gone global!

Any pollution affects one or more food chains with negative 'knock on' effects on other organisms in the complex food webs of any ecosystem - so biodiversity decreases.

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(b) Reduction of biodiversity - sources of waste and pollution and their management

Introduction - sources of the biodiversity problem

As our ever increasing world-wide consumer society demands more and more and use more and more of the Earth's resources, so we create more and more waste from producing and consuming food, plastics, metals and burning fossil fuels for energy.

We need to minimise the formation of polluting gases and chemical waste to minimise the harmful polluting impact on the environment and its fragile ecosystems-biodiversity - its unlikely we will reduce this impact to zero, but we can try a lot more effectively!

Ideally we should try to reduce waste and pollution by recycling materials, but this isn't always possible, but we can try to minimise pollution of the atmosphere, water and land, all of which has a negative effect on biodiversity!

 

Air pollution and reduction of biodiversity

(i) Burning fossil fuels emits acidic gases like sulfur dioxide and nitrogen oxides - all of which are harmful to us and other organisms the environment.

Trees and fish are especially sensitive to acidic water after the acidic gases dissolve in rain which falls into lakes and rivers (I've measured rainwater pH as low as 3.5). See acid rain project

In this UK (NE England) based project we have monitored acid rain from UK fossil fuel power stations (thankfully much decreased now in 2020), but we have monitored acidic rain carried in air masses from continental Europe - even as far as from Eastern European countries like Poland and the Czech Republic,  which still rely very heavily on coal.

Acid rain has several damaging environmental impacts e.g.

The leaves and roots of plants are damaged by acid rain, inhibiting photosynthesis (making food) and uptake of nutrient ions (deficiency).

Acid rain washes out nutrient mineral ions from the soil, another cause of mineral deficiency in plants.

Acid rain also washes out from soil/rocks harmful ions like aluminium (Al³⁺), which end up in lakes and rivers. Aluminium affects the gills of fish, results can be fatal.

Most fish and other aquatic organisms are affected if the pH of water falls below 4 and many cannot survive the acidic conditions.

You can operate desulfurisation processes in power stations to reduce sulfur dioxide emissions and use catalytic converters in road vehicles to reduce nitrogen oxides.

 

(ii) Road vehicles are also emitting carbon (soot) and hydrocarbon (C_xH_y) particulates which are being taken in and absorbed by our bodies.

We are just learning how so many particulates are getting into our bloodstream and organs, potentially having harmful effects - its an important current area of scientific research.

Many countries have strict anti-pollution laws to minimise polluting air emissions - also regulations to control toxic waste chemicals, use of landfill sites and treatment of sewage.

For more details on certain aspects of air pollution see ...

Fossil fuel air pollution - incomplete combustion, carbon monoxide & soot particulates

and Fossil fuel air pollution - effects of sulfur/nitrogen oxide gcse chemistry notes

 

Water pollution and reduction of biodiversity

(i) Overuse of fertilisers (agrichemicals), some of the material runs off with rain into streams, rivers and lakes so the water contains too much nitrates and other nutrients in excess of what aquatic organisms need.

This causes an overgrowth of choking algae and weeds that block light reaching life below the water surface - the effect is called eutrophication.  The plants can't synthesise and die and begin to decompose.  The decomposer microorganisms respire and multiply using up any remaining oxygen in the water.

This deoxygenation of the water kills most other aquatic life requiring oxygen for respiration e.g. fish and crustaceans, so food chains/webs badly affected - far less biodiversity in the aqueous habitat.

Synthetic fertilisers should be used to the minimum required and in a pellet form that slowly releases the nutrients, hopefully absorbed by plants with no excess run-ff into water systems. See also Use of NPK fertilisers and environmental problems

(ii) Oil spills from broken pipelines on land or tanker accidents at sea lead to destruction of wildlife, particularly of aquatic organisms like seabirds and other animals in the sea.

A large and costly clean-up operation must then be put in place.

Pollution, Accidents and Economic Aspects of the Petrochemical Industry

(iii) Domestic sewage contains pathogens that can kill aquatic life.

Sewage also contains all sorts of chemicals we have used in household products.

No domestic effluent should be allowed to flow into water systems untreated.

Untreated sewage entering waterways may carry polluting chemicals, parasites and microbial pathogens.

Microorganisms that decompose sewage use dissolved oxygen water in respiration, threatening the life of aquatic organisms.

(iv) Anti-pest agents used in agriculture - agrichemicals (water and land pollution)

The overuse of toxic pesticides, fungicides and herbicides has had a dreadful effect on non-harmful organisms such as wild flowers and insects like bees - important pollinators.  They pollute both land (contaminated) and water (washed into by rain).

Toxic pesticides can be washed of farmland into water courses and these can increase in concentration up a food chain or they can accumulate in soil.

Food chains are affected - animals rely on plants or other animals for their survival, and ecosystems imbalanced and biodiversity is considerably reduced. Pollutants enter the food chain and passed on from one trophic level to the next, with increasing concentration - animals like top predators suffer the most e.g.

Cabbage ==> butterflies lays eggs - resulting caterpillars feed off cabbage ==> butterflies eaten by blue/great tit birds ==> bird of prey eg kestrel, catches smaller birds eg blue/great tits.

In this pyramid of biomass: 1 = cabbage, 2 = caterpillar, 3 = blue tit bird, 4 = bird of prey (raptor).

BUT, up the food chain, herbicides or pesticides can increase in concentration and often affect the top (apex) predator the most.

Before being banned in many countries, the insecticide DDT was being passed up the food chain - it is soluble in fat and reached dangerous levels in birds of prey. It affected the thickness of egg shells, so the eggs were easily broken prematurely and chicks unable to hatch out and survive in a healthy state.

A classic example of build up of poisons like pesticides in a simple food chain:

treated crops ==> eaten by small birds ==> birds of prey, predate on small birds

If the crops, eaten by birds, are treated with pesticides (herbicide or insecticide) the poison can concentrate in fatty tissue and then concentrates in the next organism in the food chain, with devastating effects on the population of top predators.

The overall process of increasing toxin concentration is called bioaccumulation.

 

(v) Chemicals from industry

Waste from chemical processes must be carefully dealt with and not allowed to leak out and pollute water courses - streams, rivers and lakes.

Certain metal compounds and chemicals used in manufacturing plastics all have very detrimental effects on organisms.

 

(vi) Fish farming

Fish can be in large enclosed nets in the open water of a lake or in sheltered bay of sea water. The adult fish can be regularly harvested and replaced with smaller younger fish.

Unfortunately there are environmental issues which reduce biodiversity.

(a) Food is added to the enclosed nets to feed the fish, who then produce large amounts of waste.

The waste can leak out causing eutrophication and death of wild species - the waste contains pathogens.

(b) Fish farms are breeding grounds for parasites, again these can escape and threaten wild species.

(c) Predators like seals and sea lions are attracted this food resource, but can get trapped in the nets and die.

(d) The farmed fish can escape and compete with indigenous species of fish for food resources AND may hybridise with indigenous species, this dilutes the natural genes of the natural native fish, weakening them (reduces their fitness) to survive in our seas and oceans.

(e) Fish tank farms only contain one species and are therefore low on biodiversity - they are also kept free of any plants or predators, the parasites and microorganisms are usually killed.

Many countries have strict anti-pollution laws to regulate the control of chemical toxic waste, use of landfill sites and treatment of sewage.

 

Introduction of non-indigenous species

Reminder: An indigenous species is one that occurs naturally in a given environment i.e. it is not there by accident or deliberate introduction into an area.

A non-indigenous species is one that does NOT naturally live in a particular habitat (not native to an area) and they maybe beneficial or harmful to an environment. Their occurrence may be accidental or deliberate introduction. The main problem they cause is out competing native species e.g. grey squirrels outcompete red squirrels, an example of reducing biodiversity of native species.

Non-indigenous species will compete with naturally occurring indigenous species.

If they can out-compete, a non-indigenous species can reduce the population of an indigenous species e.g. in the UK grey squirrels can out-compete the native red squirrels for food and territory.

They be introduced deliberately for food or hunting.

They can also enter a habitat accidentally e.g. a plant or animal on the cargo of a ship.

Non-indigenous species can 'accidentally' introduce new pathogens, causing disease to spread through indigenous populations.

 

Change in use of land - how the landscape is changing

There are significant changes going on in the way that we manage land.

Deforestation of many of the world's greatest forests in South America and Asia is happening now and at an alarming rate.  Large areas of forest are being destroyed in favour of removing trees to clear the land to raise cattle and grow crops - often amounting to monoculture - just one principal animal or plant product.

In agriculture intensive farming for one particular crop is replacing more traditional crop rotation methods.

The land of natural habitats is being used for factories, houses, mining and quarrying and motorways etc.

However needed these are, they all considerably decrease biodiversity.

 

Land pollution and reduction of biodiversity

(i) Domestic waste is becoming an increasingly worrying problem as the world's population increases along with  rising standard of living - both contribute to the waste problem.

Much of our household waste is dumped in landfill sites ('rubbish dumps') from which pollutants can leach out.

Organic material in dumps is anaerobic ally decomposing giving off methane gas - a powerful greenhouse gas - much more so than carbon dioxide, which is also given off from aerobic respiration.

Decomposer organisms can respire both aerobically and anaerobically, but landfill sites tend to have low oxygen levels below the surface, which encourages decomposers to respire anaerobically, hence the emission of methane gas rather than carbon dioxide. This means landfill site decomposition contributes more to global warming than the natural decomposition in the carbon cycle.

Cattle 'farting' is a notable producer of methane gas from the action of anaerobic decomposing bacteria in the cow stomachs.

Water saturated fields, especially where the soil is very compact, inhibits the diffusion of air (oxygen) into them, encouraging the action of anaerobic decomposing bacteria to produce methane.

Recycling things like plastic, metals and garden waste can help reduce the burden of landfill sites.

Landfill sites use up space once occupied by wildlife, the less space we need the better and existing landfill sites need to monitored for pollution effects and eventually, after their useful life, the land restored to a good ecological state and the local biodiversity greatly improves!

Many supermarket chains and other retail businesses are moving away from plastic packaging to returning to use recyclable paper.

 

(ii) Overuse of anti-pest chemical agents on farm land - see water pollution

 

(iii) Oil spillages contaminate both land and water - see above in water pollution.

Pollution, Accidents and Economic Aspects of the Petrochemical Industry

 

(iv) Nuclear waste is buried underground or stored in tanks of water.

Highly radioactive waste from nuclear power reactors is highly toxic (cancer forming) and must be processed (at great cost) to separate what can be re-used in nuclear reactors and what must be safely stored.

Unfortunately the half-life of some radioisotopes is in the region of thousands of years - so that's a long term storage and management problem - no leaks into the environment is acceptable, but thy happen!

See also in gcse chemistry and physics revision notes

Dangers of radioactive emissions - health and safety issues

Half-life of a radioisotope - how long is it radioactive? implications!

Reminder: Many countries have strict anti-pollution laws to regulate the control of chemical toxic waste, use of landfill sites and treatment of sewage, and of course the processing and storing of nuclear waste.

See also

Metal extraction - economics, environmental Issues and recycling gcse chemistry revision notes

Polymers, plastics, poly(ethene), poly(propene), uses - problems and recycling gcse chemistry

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Key points - Summary of ideas

Based on the syllabus-specifications for students taking the AQA, Edexcel and OCR GCSE level biology examinations (~US grades 9-10).

• Pollution impacts biodiversity negatively.

• Managing waste and pollution reduces habitat destruction and supports ecosystems.

• Strategies include recycling, afforestation, pollution control laws.

• Global cooperation is essential for effective environmental conservation.

Management of Waste and Pollution to Improve Biodiversity

Waste and pollution have significant negative impacts on biodiversity in terrestrial, aquatic, and atmospheric environments.

Managing waste and reducing pollution effectively can help conserve ecosystems and protect diverse species.

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1. Pollution and Its Effects on Biodiversity

Land Pollution

• Causes: Waste disposal (landfills), deforestation, use of pesticides and fertilizers, industrial waste.

• Effects: Habitat destruction, soil degradation, reduced fertility, toxic chemicals harm plants and animals.

• Solutions:

  • Sustainable agriculture – organic farming, crop rotation.

  • Recycling and waste reduction – composting, using biodegradable materials.

  • Proper waste management – regulations on landfill sites and industrial waste disposal.

Air Pollution

• Causes: Vehicle emissions, burning fossil fuels, industrial processes, deforestation.

• Effects: Acid rain, respiratory diseases in organisms, climate change, destruction of habitats.

• Solutions:

  • Use of renewable energy – solar, wind power.

  • Reducing emissions – electric vehicles, catalytic converters in cars.

  • Afforestation & reforestation – planting trees to absorb CO₂.

Water Pollution

• Causes: Sewage disposal, oil spills, agricultural runoff (pesticides, fertilizers), plastic waste.

• Effects: Oxygen depletion (eutrophication), poisoning of aquatic organisms, disruption of food chains.

• Solutions:

  • Water treatment – sewage treatment plants.

  • Reducing agricultural runoff – buffer zones, organic farming.

  • Plastic waste management – bans on single-use plastics, clean-up projects.

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2. Waste Management Strategies for Biodiversity Conservation

Reduce, Reuse, Recycle

• Reduces landfill waste, lowers pollution levels, and conserves natural resources.

• Examples:

  • Reusing materials (glass, plastics).

  • Recycling paper, metals, plastics.

  • Minimizing waste production by reducing consumption.

Biodegradable versus Non-Biodegradable Waste

• Biodegradable waste breaks down naturally (e.g., food scraps, paper).

• Non-biodegradable waste does not break down easily (e.g., plastics, metals).

• Solutions:

  • Encourage use of biodegradable packaging.

  • Reduce single-use plastics.

  • Develop biodegradable alternatives.

Toxic Waste Disposal

• Safe disposal methods prevent contamination of ecosystems.

• Examples:

  • Proper chemical disposal.

  • Using designated hazardous waste sites.

Circular Economy Model

• Aim: To minimize waste by designing reusable and recyclable materials.

• Benefits:

  • Lower environmental pollution.

  • Sustainable production and consumption.

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3. Government Policies and Global Efforts

Environmental Protection Laws

• Governments worldwide enforce regulations to manage waste and pollution.

• Examples:

  • Clean Air Act – Limits industrial emissions.

  • Water Protection Laws – Controls pollutants in rivers and oceans.

  • Plastic Waste Bans – Reduces environmental damage.

International Initiatives

• Kyoto Protocol & Paris Agreement – Targets reducing greenhouse gases.

• UN Biodiversity Agreements – Aims to conserve species and ecosystems.

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4. Impact of Pollution Control on Biodiversity

• Improved air quality → healthier ecosystems & species survival.

• Protected water bodies → sustains aquatic life.

• Reduced land pollution → preserves forests and wildlife habitats.

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Summary of learning objectives and key words or phrases

Be able to describe the various reasons and factors contributing to the fall in biodiversity.

Appreciate that population growth increases the need for more raw materials and natural landscapes being depleted of habitats for wildlife.

Be able to describe the effects of pollution of land e.g. landfill sites, water pollution from fertilisers, chemical industry, sewage and pesticides and air pollution from acid rain and carbon monoxide and hydrocarbon particulates from road vehicles.

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