1. The Environment

1.1 Definition: Is all of the external factors affecting an organism. These factors may be other living organisms (biotic factors) or non-living variables (abiotic factors such as temperature, rainfall, day length, wind and ocean currents. The interactions of organisms with biotic and abiotic factors form an ecosystem. Ecosystem refer to organisms living in a particular environment such as forest or a coral reef and the physical parts of the environment that affect them.

1.2 Major Component

The major components of the environment are:

1. The lithosphere i.e. the worlds of rock
   2. The atmosphere i.e. the air
   3. The hydrosphere, i.e. region occupied by water
   4. Biosphere i.e. the living things
   5. Pedosphere i.e. the soil

Note: Environment where all of those worlds interact are often the most complex and productive on earth, i.e. the soil.

2. Soil as Environmental Interface

The importance of soil as a natural body derives in large part from its role as an interface between the worlds of rock, air, water and biosphere. The concept of the soil as interface means different things at different scales. At the scale of kilometres, soil channel waters from rain to rivers and transfer mineral elements from rocks to the oceans. They also run over and supply vast amount of atmospheric gases substantially influencing the global balance of methane and CO₂. At a scale of few meters, soil forms the transition zone between hard rock and air, holding both liquid water and O₂ gas often used by plant roots. It transfers mineral elements from the earths’ crust to its vegetation. It processes or stores the organic remains of terrestrial plants animals and man. At a scale of few millimetres, soil provides diverse microhabitats for air-breathing and aquatic organism, channels water and nutrients to plant roots and provides surface and solution vessels for thousands of biochemical reactions. Finally, at a scale of a few micrometers and less, soil provides ordered and complex surfaces, both mineral and organic that acts as templates for chemical reactions and interacts with water and solutes. Also, at this scale its tiniest mineral particles form micro-zones of electromagnetic charge that attract everything from bacterial cell wall to proteins to conglomerates of water molecules

3. Factors Threatening the Environment

1. Population Growth- As number of people increases, crowding generates pollution, destroys more habitats and uses up additional natural resources. The major problem i.e. growth in population that is not accompanied by proper environmental planning.
   
   
2. Global Warming- Like the glass in a green house, certain gases in the earth’s atmosphere permits the sun’s radiation to heat the earth. At the same time, these gases retard the escape into space. The infrared energy radiated back out by earth. This process is referred to as the green house effect. These gases primarily CO₂, CH₄, N₂O and water vapour insulate earth’s surface, helping to maintain warm temperatures. However, when the concentration of these gases rise, they trap more heat within the atmosphere causing worldwide temperature to rise. Others:
   
   
3. Depletion of the Ozone layer- Ozone layer is a thin band in the stratosphere (layer upper atmosphere) which serves to shield the earth from the sun’s harmful ultraviolet rays.
   
   
4. Habitat destruction and species extinction
   
   
5. Air pollution
   
   
6. Water pollution
   
   
7. Ground water depletion and contamination
   
   
8. Chemical risks- Toxic substances that humans encounter regularly which poses health risks, e.g. 1. Pesticide residue in vegetables and crops; and 2. Mercury and others in fish i.e. Food chain problem.
   
   
9. Environmental Racism- Studies have shown that not all individual are equally exposed to pollution. For example, worldwide toxic waste sites are more prevalent in poorer communities.
   
   
10. Energy production- Typical example i.e. environmental effects of the fossil fuel age. Fossil fuel exploration/production contributes to global warming, air pollution, acid rain, etc
    
    
    NOTE: There are a lot of international treaties to combat these global problems