Module 4: Environmental Studies 

Module 4: Environmental Studies 

Human influences on the environment: 

What makes up the environment? 

  • The place where an organism lives is known as a habitat
  • Conditions in a habitat can be both abiotic and biotic
  • Abiotic: Temperature, humidity, light, water
  • Biotic: Living organisms
  • Abiotic and biotic make up the environment/support life

 

What makes an environment sustainable?

  • Sustainable environment is achieved by using natural resources at a controlled rate so they do not run out/ damage the environment
  • Physical resources: Land, water, air
  • Biological resources: Forms of plants/animal life
  • Sustainable development: Development of industry, agriculture, housing – improving the quality of life without damaging the earth’s renewable resources
  • Ecological balance, economic growth, social responsibility must all work together

Natural resources: The resources produced by nature that are useful or necessary for life 

 

How are humans affecting the environment?

Pollution: 

  • Addition of any elements (a pollutant) into an ecosystem – causes damage to the living organisms/ the environment
  • Three main sources of pollution are industry, agriculture, domestic
  • We will look at three elements where pollution has greatly impacted human health
  • Air (Atmosphere)
  • Water (Hydrosphere)
  • Land (Lithosphere)


Air Pollution: 

  • Abiotic factor
  • Vital for the survival of all living organisms
  • Air pollutants made up of gases, liquids, solids present in the atmosphere – high levels harm living organisms
  • Primary pollutants: Substances given off directly into the atmosphere – carbon dioxide from burning fossil fuels
  • Secondary pollutants: Substances that are formed in the air from the reaction of primary pollutants – sulfuric acids


What causes air pollution? 

  • Increase in the amount of energy needed for industry, transportation and domestic use
  • Coal-fired power stations: Generate more electricity by burning more coal
  • Motor vehicles and aeroplanes: Burning petrol and diesel; releasing more exhaust fumes
  • Wood: Cooking and heating homes; releasing more smoke and fumes
  • Grass and forest fires: Releasing more smoke and gases into the air


PM: Complex mixture of extremely small solid/ liquid particles suspended in the air

Hydrocarbons: Chemical compounds that are made up of hydrogen and carbon atoms. Naturally occur in petroleum, natural gas, coal, wood


How do pollutants impact on the environment? 

All the processes mentioned release gas into the atmosphere – harming the environment/ human health

  • Increase in gas: Sulfuric dioxide (SO2) and Nitrous Oxide (NOx) can cause acid rain
  • Increase in chlorofluorocarbons (CFCs) destroys ozone in the stratosphere – causing the thickness of the ozone layer to decrease
  • Increase in the amount of CO2 and methane in the atmosphere leads to
  • Global warming: Increased temperatures, erratic rain, droughts world-wide
  • Smog: Restricts sunlight from reaching the earth – prevents plants from photosynthesizing

Acid rain: Acids that form in the air from SO2 and NOX

  • Chemicals react with water vapour/oxygen in the atmosphere to form sulphuric acid/ nitrate acid
  • Reduces the pH of water, increased acidity causes the death of invertebrates


Smog: Mixture of ozone, smoke and fumes dispersed in fog

  • Brownish yellow cloud
  • Temperature inversion/ a lot of smoke in the air from fires

How does air pollution affect human health? 

  • Major cause of respiratory/ cardio-vascular system diseases (Emphysema, asthma)
  • Lungs damaged – more vulnerable to lung diseases caused by pathogens (pneumonia, TB, Chronic Bronchitis)
  • Depletion of the ozone layer allows more ultra violet radiation – causes skin cancer/ destroys phytoplankton – basis of marine food chains
  • Radiation from nuclear reactors, uranium mines, X-Rays – cause leukaemia, bone tumours, genetic abnormalities
  • Brain diseases – Parkinson’s, motor neuron disease, dementia, Alzheimer’s 


How can air pollution be reduced? 

  • Replacement of the combustion of carbon-based fossil fuels – renewable alternative sources of energy (wind turbines, solar, hydroelectric, wave generated power)
  • Catalytic converters: Fitted to all exhaust systems – reduce emissions such as nitrous oxide
  • Conversion of vegetation as plants absorb carbon dioxide/ release oxygen
  • Control the burning of vegetation
  • Save energy in every possible way – install solar panels
  • Reduce gas emissions by: Making public transport more efficient – reduce number of                        
  •                                               cars on the road
  •                                               Controlling gas emissions
  •                                               Enforcing laws ensure emissions are filtered from industrial                    
  •                                               sites to reduce toxic pollutants

Water Pollution: 

  • Water pollutants: Organic waste, sediments, minerals, nutrients, thermal pollution, chemicals


The following causes water pollution: 

  • Toxins in waterways from agriculture
  • Pathogens in sewage
  • Accelerated eutrophication
  • Pollutant discharged into the sea


Toxins in water: 

  • Pollutants enter waterways directly through runoff from the land
  • Groundwater, rivers, dam – all polluted by toxins

Pesticides used in agriculture: 

  • Chemical insecticides – kill pests
  • Chemical Herbicides – kill weeds
  • Agriculture activities tend to be concentrated near rivers – river overflows; pesticides may get washed into local streams, rivers lakes, groundwater
  • Chemicals can be absorbed by aquatic organisms – fish, shellfish are no longer safe to eat because they have been contaminated


How can the use of pesticides be reduced: 

  • Farmers must stop using persistent pesticides
  • Biological control is a much safer way of controlling pests – this involves using a natural predator – keeps the pest’s population low
  • Using biological control has an advantage of being cheaper, not causing pollution, only killing pests


Heavy metals from mining/industry: 

  • Factories use water from rivers to power machinery/ cool down machinery
  • Dirty water containing chemicals is put back in the river (zinc, cadmium, lead)
  • If chemicals occur in high concentration they kill fish, other fauna immediately
  • Humans can be affected by drinking contaminated water/ eating fish/ other aquatic organisms; pollutant accumulated in their tissues


How can the effects of toxins be limited?

Government/ municipalities must create waste management – prevent waste from seeping into waterways

  • Monitoring emissions from industries: Regulations governing the release of dangerous chemicals – they are not strictly enforced
  • Providing incentives: Encourage mines/ factories to adopt cleaner production processes – reducing the amount of waste


Pathogens in sewage: 

  • Common water pollutants are pathogens found in sewage

Pathogens: Organisms that cause disease

What is sewage?

  • Sewage is waste water from houses/ industries which contains many other substances – urine, faeces, toilet paper, detergents

 

What effect does untreated sewage have on human health? 

  • World’s leading diseases – pathogens either breed in or spread by water
  • Drinking water/ food contaminated with untreated sewage can cause gastrointestinal diseases (Dysentery, cholera, typhoid)


How can sewage pollution be reduced: 

  • Good sanitation is very important
  • Water should be recycled – done in water waste treatment plants or in a septic tank system
  • More toilets must be built – in rural areas/ informal settlements

Composting/urine diversion toilets are practical and inexpensive. Urine is separated from the faeces so the latter can dry out, decompose quickly/ be used for compost


Accelerated eutrophication: 

  • One of the damaging results of social/ economic development in the country has been the increase in the amount of nutrients from various sources, washed into rivers/ water reservoirs causing eutrophication
  • Eutrophication has become a widespread environmental problems of inland/ marine waters

Eutrophication: Enhanced growth of algae due to too many nutrients, mainly phosphates/ nitrates

Where do these nutrients come from?

Nutrients that cause eutrophication come from:

  • Runoff of inorganic fertiliser
  • Natural runoff of nutrients from the soil/ the weathering of rocks
  • Runoff of manure from farms
  • Waste from abattoirs/feedlots
  • Discharge of detergents (with phosphate)
  • Discharge of untreated sewage


What are effects of excess nutrients? 

  • Nutrients encourage excessive growth of aquatic weeds/ blue-green algae (cyanobacteria)
  • Forms a thick, green scum – surface of the water known as algal bloom
  • Blooms can occur in marine, estuarine, fresh water – those occurring in fresh water are the biggest concern
  • Blooms cause the clear water to become cloudy so light cannot penetrate – plants below cannot photosynthesize = dead plants; this increases the dead plant biomass
  • Bacteria/ fungi decompose the dead organic matter and multiply rapidly – using much of the oxygen in the water. Causes the death of many fish/ other aquatic organisms – may result in a dead rive or dam

Eutrophication can severely degrade water quality/ threaten human health


How can eutrophication be prevented: 

Prevent leaching of nutrients, fertilizers should not be applied:

  • In excess
  • To empty fields
  • Just before rain
  • Near streams/ rivers

Pollutants discharged into the sea: 

Marine pollution is a growing environmental challenge

  • Discharge of untreated sewage
  • Coastal mining
  • Bad farming
  • Contaminated storm water

Oil spills – oil tankers accidently running aground/ illegally discharging ballast/ bilge water containing toxic compounds

Oil floats on the surface poisoning/ killing fish, marine animals, seabirds

Fishing lines/ plastic packaging entangle and kill marine animals

What can be done to limit marine pollution? 

  • Legislate against sewage, chemicals, other toxins being discharges into rivers/ coastal rivers
  • Oil tankers – regularly serviced
  • Legislation limiting the amount of oil tankers might transport
  • Prosecute ships owners for discharging oil from ships
  • Travel routes of oil tankers – better monitored by aircraft patrolling shipping lanes


What can you do to keep our waterways clean? 

  • Do: Teach your family/ friends to keep water clean
  • Do not: Urinate/ defaecate near a source of water
  • Throw rubbish into streams/ rivers
  • Use dirty containers to collect water
  • Contaminate water sources with soap/ detergents
  • Pour chemicals down the sink/ storm water drains


Land Pollution: 

What is land pollution? 

  • Degradation of the earth’s land surface that could otherwise be used constructively


What causes land pollution? 

  • Misuse of the soil – poor agricultural
  • Mineral exploitation
  • Industrial waste dumping
  • Indiscriminate disposal of urban waste
  • It incudes – visible waste, litter, pollution of soil


How does land pollution affect humans? 

  • If waste is not disposed of – accumulates into unsightly, smelly piles
  • Accumulation of organic matter – vermin, flies, mosquitoes, associated diseases
  • Release of toxic chemicals/ harmful effluent from agriculture/ industry – making soil unfit for plant growth (land is taken out of circulation)

How can land pollution be reduced? 

  • Municipalities to improve the quality of the environment – better waste management
  • Mining companies to clean up mines/ restore the landscape after the mine is spent
  • Farmers use less harmful, persistent pesticides/ herbicides
  • Farmers to practice organic farming – reduce the use of pesticides
  • Recycle house hold waste as much as possible
  • Reduce litter that is unsightly; lowers the value of properties – discourages tourists
  • Buy biodegradable products
  • Avoid buying packaged items


Local, national, global issues:

Ozone depletion:

  • Ozone (O3): Colourless gas, harsh odour. It is an unstable form of oxygen – three oxygen atoms

What is the ozone layer? 

  • Ozone layer is a renewable layer of ozone in the stratosphere
  • Ozone molecules are constantly being formed, broken down, reformed
  • Layer of ozone absorbs 99% of the harmful incoming ultraviolet radiation
  • Ozone layer acts as a shield and protecting life from the harmful effects of the UV radiation
  • Thickness of the ozone layer has been decreasing


What is causing the depletion of ozone? 

  • Human activities are causing the depletion of the ozone layer
  • Chemicals (Chlorofluoro-carbons) were manufactured to be used in refrigerators, air conditioners, propellants in aerosol 
  • Billions of CFC molecules have been released into the air

CFCs: Manufactured chemicals made up of chlorine, fluorine, carbon


How do CFCs break down ozone?

  • CFCs are released into the atmosphere – remain unchanged in the lower part of the atmosphere (they are stable and non-reactive)
  • Gradually diffuse up to the stratosphere – ultraviolet radiation breaks them down into chlorine atoms react with the ozone molecules
  • Chlorine atoms react with the ozone layers – ozone is breaking down faster than it is being formed, causing the ozone layer to become thinner
  • Less natural protection from harmful ultraviolet radiation


What are the consequences of ozone depletion? 

  • If the ozone layer is depleted a lot more ultraviolet radiation will reach earth
  • Increased exposure to ultraviolet radiation, higher incidents of skin cancer/ cataracts
  • Destroys phytoplankton: Less food will be produced/ Oxygen levels will be reduced


How can ozone depletion be decreased? 

  • Don’t buy aerosol products with chlorofluorocarbons
  • Repair refrigerators, freezers, air conditioning units immediately
  • Use eco-friendly household cleaning products
  • Use compact fluorescent light bulbs


Greenhouse effect/ global warming: 

  • Earth’s atmosphere contains several different gases – act as a blanket, which keeps earth warm (Known as the greenhouse gases)
  • Water vapour/carbon dioxide – two of the most important greenhouse gases
  • Methane is another important greenhouse gas


What is the natural greenhouse effect? 

  • Allow solar radiation – shortwave radiation (visible light); sun to pass freely through the atmosphere. These rays are partly absorbed by the ground, sea, air, this makes the earth’s surface warm
  • Long wave – Infrared radiation (light that cannot be seen) is given off from the surface of the earth
  • These rays leave earth’s atmosphere – go into space
  • Some of these rays cannot pass through the greenhouse gases, they become trapped within the lower part of the atmosphere – reflected back to earth
  • This results in the earth heating up – this process is called the natural greenhouse effect
  • Sufficient heat is trapped around earth to sustain life
  • Radiant energy is used for various life processes (photosynthesis)


What is the enhanced greenhouse effect? 

  • Human activities: burning fossil fuel; releasing more greenhouse gases (carbon dioxide/ methane)
  • Increased concentration of greenhouse gases will trap more infrared radiation – reflected back to earth