Population, natural resources
End of the World
Water cycle in the environment
Water cycle in the environment, a hydrological cycle in other words, is a chain of phenomena. Water, an omnipresent element of the environment and the basic building material of all living organisms, undergoes various transformations. We do not know where it comes from or, at least, we are not able to say when and how it appeared on the Earth; however we have two thesis ideas which say about its source. According to one of them first water resources emerged from magma in innumerable volcanic processes. The second thesis says that water is the result of the reaction of hydrogen atoms carried with oxygen atoms by solar wind in the Earth's atmosphere.
Since we do not know the source of water and we are not able to distinguish the beginning of water cycle, let us start from the biggest water bodies - oceans.
Water cycle in the environment is forced by climatic factors: temperature (the Sun) and winds. The Sun heats water in oceans and as the result the water evaporates. Due to air cycle, water vapor accumulates in various levels of the atmosphere creating clouds. Winds and currents make this store of the condensed vapour move freely all over the Earth. After some time, in favourable conditions (e.g. air cooling), molecules of vapour contained in clouds condense more or even freeze and fall on the Earth in the form of precipitation (rain, snow, hail). Some part of the water which does not soak in soil, flows into rivers and with the rivers it flows into seas and oceans whereas the water which soaks in the upper layers of soil feeds plants and, partly filtered through soil, flows into surface water (water bodies) from which it evaporates or returns to oceans. Groundwater which gathers in the lower layers of soil becomes underground streams and flows deeply under the surface of the Earth and, in any event, flows into bigger water bodies and then into oceans.
In every stage of this cycle evaporation takes place and thus not only are oceans responsible for the creation of clouds but also all water bodies and all life and civilization processes associated with water.
Methods of water protection
Data gathered for the purpose of the United Nations in "The report on the condition of water economy in the world" (2003) shows that water resources are decreasing drastically per one inhabitant of the Earth. One of the reasons is the rise in the population of our planet. Although the birthrate has fallen in many rich countries, population is still increasing. According to the report, water consumption has doubled for the last fifty years. Apart from the increase in population (mainly in poorly developed countries), one of the reasons is climate change (its influence is assessed at about 20%) which disturbs water cycle: on one hand, in relatively wet areas the amount of precipitation, the main source of drinking water, increases; on the other hand in dry regions and areas threatened with droughts and considerable decrease in precipitation (the tropics, subtropics) this level is going to fall even more. Finally, another threat is increase in the amount of undrinkable water due to pollution.
So how can we protect water resources so as not to deteriorate the condition of water? First of all, we should become aware of the fact that water is one of natural resources and its amount in water cycle is limited, especially the amount of fresh water (only 4% of water is fresh water whereas salt water constitutes 96% of water resources). Due to unreasonable water economy and pollution, water resources are shrinking and they are not something that can be easily restored. As far as the protection of water is concerned, the most important thing is to use them sensibly, which means:
Harmful and toxic substances in water ecosystems
This is human that is mainly responsible for water pollution, regardless of which direction they emit harmful substances in. Water is polluted directly (sewage) but also, in large measure, indirectly. Water, while circulating, gathers all kinds of pollution from the air and soil (pollution penetrates into ground water).
The main substances which pollute water bodies and which people are responsible for, include: