Human and his role in the environment.

         Human has always exploited the Earth's resources to satisfy his needs. Indeed, he knew how to exploit various capitals of his planet in assets such as energy reserves. Let us cite coal, iron, uranium mines and even oil slicks. However, it appears that these reservoirs are not inexhaustible.

        By developing the territory, human modifies his natural environment: he sometimes destroys living environments. However, he gradually becomes aware of the dangers he poses to the planet and begin to restore environments that it has transformed.

        To understand the relationship and role of man with his environment, we must first know how man has modified and altered his environment? What means are implemented to preserve the natural balance and avoid pollution?

I. Changes to the environment

         Due to the increase in the population of cities, we must build new homes, new communication routes (roads and highways, railways, etc.). The earthworks caused by the construction of these connections between major cities are impressive, the volumes of rocks displaced are considerable. The topography of the land changes: millions of tonnes (of cubic meters) of materials are extracted, transported and then deposited in other places. The landscapes are therefore totally transformed.

II. Harmful actions

1. Discharge of waste:

• The increase in domestic or industrial waste released by humans modifies environments and sometimes makes them unfit for life. The diversity of animal and plant species is reduced.

• Industrial waste is discharged, most of the time, into river water. We are also witnessing fallout of pollutants through the atmosphere (rain acids). The most dangerous pollutants are heavy metals like mercury, lead, etc. The waters can be clear and, despite everything, polluted by these heavy metals. Thus, at Minamata in Japan, hundreds of people died because they ate fish caught in waters polluted by mercury released by a chemical factory.

2. Oil spills:

   Oil spills, due to oil tanker accidents (the Erika in 1999), also represent real ecological disasters. Birds, for example, are very affected by these oil spills. Their feathers, stuck by the black oils, no longer allow them to fly: they are condemned to die. On the coasts affected by these disasters, the fauna and flora are destroyed. It then takes a lot of time and work to allow this environment to regain its natural appearance and population.

3. Intensive fishing:

• Due to the population explosion in the 1950s, the need for animal food increased. For example, fishing was developed and fish reserves were drawn on without control until the 1970s.

• Although fishing is sometimes regulated, current fishing techniques and gear remain extremely efficient. Satellites help fishermen navigate to the waters with the most fish. On boats, schools of fish are spotted using sonars. Trawlers have increasingly large nets, which allows very significant fishing, sometimes devastating for the marine environment. Man is therefore responsible for the significant decrease in the number of individuals of different species.

III. Favorable actions

The creation of wastewater treatment plants:

• Aware of the damage caused by the discharge of waste into nature, human builds treatment stations which allow wastewater to be treated after its use.

• The wastewater is, firstly, cleared of solid waste by screening (larger materials), by desanding (heavier materials) and by degreasing (lighter materials). The elimination of organic pollution dissolved in water can, moreover, be carried out using bacteria which digest the polluting materials and transform them into sludge. A decanter collects the sludge which is recycled. We can thus return purified water to nature.

* Solid waste recycling:

        The recovery of waste by recycling makes it possible to save on raw materials and contribute to safeguarding the environment. Thus, car batteries provide almost half of the recycled lead. Agricultural residues from tree pruning and lawn maintenance on sports fields represent a very significant volume. These residues are crushed, transformed into compost and used to fertilize the soil for crops.

* The creation of nature reserves:

         Forests have undergone significant modifications due to human action. This is why nature reserves were created. These demarcated territories are regulated with a view to safeguarding all the animal and plant species that live there. Hunting is, of course, prohibited.