The water cycle
How do substances get into the water? Water, our planet’s most precious and life giving resource, has a continuous movement on, above and below the surface of the Earth and changes different states from liquid, solid (ice) and vapour. This constant move from one state to another, and the travel of water through its different form, can impact the quality of water by numerous factors: the presence of minerals such as limestone and dolomite, the agricultural pollution with fertilizers and pesticides, various contamination like oil residues and solvents, and industrial emissions, mainly exhaust gases and dust.
- Condensation – Water vapour in the air is changed into liquid water, forming clouds. Clouds may produce rainfall, which is the first route for water to return to the earth’s surface within the water cycle.
- Rainfall – Precipitation is the water release from clouds to Earth. Rain, sleet, snow, or hail are hence several primary connections in the water cycle that provides to deliveries of atmospheric water to the earth. Cloud systems can travel immense distances and therefore be potentially a source of atmospheric pollution.
- Leaching – Soluble materials in the soil, like salts, nutrients, pesticide, hormones and contaminants, are washed through a lower layer of soil or are dissolved and taken away by the water.
- Ground water bed – This is a layer made of sedimentary rocks and mineral particles, an impermeable bed adjacent to the aquifer. This layer delays the movement of the water, because of its low hydraulic conductivity. The ground water can also be influenced by sea water intrusion, what happens in the Nordic countries.