10.1 - Threats to the Environment

Definition of Environmental Sustainability

Environmental sustainability means the constant condition and quality of the environment for a long period of time. However, the increased in human population has caused conflicts between fulfilling humans' needs and conserving the environment. One of the strategies introduced is the use of the recycle bins to reduce the use of non-renewable resources.

Figure 1 - Blue recycle bins are for recycling papers. Brown recycling bins are for recycling glass. The orange recycle bins are for recycling metals and plastic materials.

Threats to the Environment

Human activities are the main threats to the natural ecosystem. Long-term threats to the environment can bring negative effects to all the living organisms, including us humans.

1. Climate change and global warming

Figure 2 - The greenhouse effect. Naturally, part of the sunlight that enter the Earth's atmosphere will be reflected back into the atmosphere in the form of infrared rays. Most of the heat energy will be absorbed by the greenhouse gases present in the atmosphere such as carbon dioxide, methane, nitrogen dioxide and chlorofluorocarbon. This prevents the heat energy from being reflected back into the outer space. Heat energy that is not reflected gives warmth to the organisms to survive. However, human activities can cause increased greenhouse gases and more heat will be trapped. As a result, the temperature of the Earth rises and leads to greenhouse effect.

Factors leading to greenhouse effect and Greenhouse gases released

• Burning of fossil fuels: Carbon dioxide, nitrogen oxide
• Deforestation: Carbon dioxide
• Animal farming: Methane
• Agricultural activities (nitrogen fertilizer): Nitrogen dioxide
• Usage of cooling substances: Chlorofluorocarbon (CFC)

Figure 3 - The effect of climate change such as El Nino (left) and La Nina (right).

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2. Deforestation and loss of biodiversity Deforestation refers to action of clearing trees in a large scale. This activity is the main cause of biodiversity imbalance. Consequently, various species of flora and fauna will lose their habitats.

Figure 4 - Soil erosion and flash floods as a result of deforestation.

The main cause of loss of biodiversity is global changes caused by environmental pollutions. Illegal hunting also contributes to the decline in species population and extinction. Acid rain causes the soil to become acidic and kills aquatic organisms.

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3. Eutrophication Eutrophication is a process caused by increased growth of algae due to excessive usage of nitrate and phosphate fertilizers. As a result, the quality of air declines and aquatic organisms die.

Factors causing eutrophication:

• Detergent residues, phosphate and untreated sewage from housing areas.
• Treated sewage
• Domestic waste substances from factories
• The use of nitrates and phosphates in farming
• Animal wastes from animal farming
• Nitrates and phosphates from construction sites
• Soil erosion from mining activities

BOD refers to the total amount of oxygen needed by the microorganisms for decomposition of organic substances in the water. Higher BOD means the quality of the water is low due to the higher concentration of organic substances and decomposing microbes. On the other hand, lower BOD signifies that the quality of the water is good and has high oxygen content.

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4. Pollution

• Air pollution
  • Increased in pollutants such as gases, smoke, dust and particles in the atmosphere.
  • Negatively affects the health of humans, animals and plants.
  • Caused by exhaust fumes released from motor vehicles , smoke from industrial factories and open burning.
  • Gases such as carbon dioxide, nitrogen oxide and sulphur dioxide released will combine with water vapor in the atmosphere to form nitric acid and sulphuric acid which then falls as acid rain.

Figure 5 - Acid rain can cause the soil to become acidic (pH value less than 5) and less fertile. Besides, leaves and roots tissues will be damaged. The increased acidity of the water will reduce the population of plankton in the water. This affects the food chain and causes death to many organisms. Acid rain can also lead to skin diseases in humans.

• Thermal pollution
  • Elimination of excess heat into the water.
  • High water temperature formed from the generator in industrial factories and hydroelectric power generator plants flows into the river or lakes.
  • High temperature reduces the oxygen dissolved in the water and the survival of aquatic organisms.
  • The higher temperature also affects the biochemical process of aquatic organisms. For instance, fish eggs may hatch earlier than they should have or fail to hatch.
  • It also promotes the growth of algae and increases the BOD of water.

• Noise pollution
  • Refers to the disturbing noise which can affect human and animal health.
  • For example, the sound of vehicles, construction activities, agricultural and industrial machineries, loud music and others.
  • Can cause health problems such as high blood pressure, cardiovascular diseases, depression and headache.

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5. Human population growth explosion

• Refers to the increases in the total number of humans in a location.
• This causes reduced environmental resources, which leads to deforestation, loss of biodiversity and global warming.
• Consequently, organisms face threats such as environmental pollutions, diseases and species extinction.
• Transporting sources from another location to the demand zones.