1.7.1 Man-Environment Interaction
The study of environmental science will stress the understanding of the natural system and the processes of the earth, their implication on man, and their impact on man, as well as the impact of man on these processes. Two areas of interaction between natural systems and man have been recognised within environmental science. Geo and eco-science. In geoscience, interaction is in the realm of physical phenomena. Here, we are concerned with the components and processes of the atmosphere, lithosphere and hydrosphere. In Eco-Science, interaction is in the realm of biological phenomena. The emphasis is on the function and components of the biosphere. The interaction of man with the natural systems can be looked at from two viewpoints:
- The impact of natural environmental forces on man. For example, floods, earthquake and landslides
- The impact of man upon the environment. For example, the air and water pollution, the extinction of certain species of animals, and the accelerated rate of erosion. In the broadest sense, the environment, which is the focus of study of environmental science, consists of all matter and energy capable of influencing life
1.7.1.1. Man and the Lithosphere INTERACTION
Man interacts with the lithosphere in several ways, and the result of the interaction may be positive or negative. As far as man is concerned, the lithosphere provides the resources as well as the resistance and environmental hazards. On the other hand, man modifies the lithosphere in many ways. Unfortunately, most of the impacts of man on the lithosphere are destructive. As far as the resources provided by the lithosphere are concerned, they are either in the form of minerals or in the form of land or processes which man can take advantage of. For example, the lithosphere provides man with minerals, soil, and water stored in water-bearing rocks. The minerals provided by the lithosphere can be divided into three (3) types:
(1) Metallic ferrous minerals, e.g. Iron, and Bauxite.
(2) Precious minerals like gold, silver and diamond
(3) Non-metallic minerals, especially the structural materials, building sands, stone, gravel, etc.
Apart from these, there are also salts like sulphur salts, chlorides and phosphate, even fossil fuels such as coal, liquid petroleum and gas. In some parts of the world, we have nuclear fuel such as Thorium and Uranium. In addition, the lithosphere also provides the non- renewable resources. These are resources whose rate of exploitation is several times greater than the rate of replenishment.
Most of these non-renewable minerals continue to increase every day. Perhaps the most important resource provided by the lithosphere is the soil. Soil is formed from weathered materials, organic matter, air and water. It is the medium of plant growth, and is therefore very crucial to man’s food supply. The physical, chemical and biological characteristics of soil determine three important qualities of land.
(1) It determines the ability of land to provide nourishment to plants and animals.
(2) It also determines the ability of land to provide water for plants, lakes and streams.
(3) Also, the ability of land to give mechanical support to plants, animals and buildings.
(4) These characteristics provide materials for construction purposes.
As far as the landforms are concerned, the landforms provided by the lithosphere have aesthetic value, and very good educational resources, e.g. Volcanoes, mountains, warm springs, icebergs, rivers, waterfalls, etc. Despite all these resources provided by the lithosphere, it also provides resistance. For example, mountains, gullies, waterfalls and gorges are most of the time obstacles to the movement of communication lines. Similarly, earthquakes, mudflows, landslides, and floods are environmental hazards where they occur. Finally, as far as man’s impact is concerned, we discover that most of their impacts are largely negative.
(1) Man extracts minerals from the lithosphere, and this may result in serious environmental consequences. For example, it could lead to what is known as the despoliation of the land surface. Scars are created on the landscape when minerals are exploited.
(2) Extraction of minerals may also lead to subsidence, which may eventually lead to mudflow.
(3) Extraction could also lead to water stream channels.
When minerals are exploited by sophisticated means, it can lead to air pollution. In some cases, when extraction is very near the sea, like the extraction of fossil fuels, it could lead to ocean pollution. Finally, man is an agent of erosion when he carries out deforestation for cultivation or building purposes. These are the complex interrelationships between man and the lithosphere.
1.7.2 Man and Ecosystem Interaction
An ecosystem is any area on the earth’s surface consisting of organisms interacting with one another and with the physical environment. Most ecosystems consist of plants and animals interacting with one another and with the physical environment in such a way that there is a circulation of nutrients between the living and nonliving components of the ecosystem and a flow of energy through the entire system.
Ecosystems have two basic components: (a) the non-living or abiotic component, and
(b) The living or biotic component. The living or biotic components can be divided into three, namely (i) the producers, (ii) the consumers, and (iii) the decomposers. The producers are those organisms that can manufacture food from simple organic substances and energy from sunlight in a complex process known as photosynthesis. They are mainly green plants. The Consumers -These are all the organisms which depend on the producers for food, either directly or indirectly.
Man, or for that matter, any other living organism must interact properly with the rest of the ecosystem because they are an integral part of that ecosystem. Some of the man’s activities, like hunting various animals, disrupt the food chains in which these animals normally take part. This disruption of one food chain affects the numerous other food chains operating in the food web. The shortening of food chains due to man’s activities, such as hunting, leads to an imbalance in the functioning of an ecosystem and ultimately in the functioning of the whole biosphere. A natural ecosystem is a delicately balanced system. If the man does not disturb this ecosystem, then the organisms like grass/producers, consumers and decomposers keep a natural balance which benefits them all and gives us a healthy environment. Natural resources are resources supplied by nature that are used by humans. These resources are classified as renewable/replaceable and recyclable in the natural system. Human being intervenes and break this cycle and changed as exhaustible resources. The other group of resources are none renewable, and human being the most accountable for the depletion of resources due to overconsumption of these resources. This is summarised by the picture.
Human activities
Agriculture Industry
Overuse of natural resources and ecosystem services
Lead to: 1. Deforestation
- Overfishing
- Pollution
These causes of soil erosion, flooding, desertification and climate change disturb the food chain/web/, nutrient cycle, and exhaust the non-renewable resources