Poisoning the Fount of Life - Fresh Water Pollution and Its Consequences
Krautz, Joachim, Contemporary Review
HUMAN life is dependent on the presence of fresh water. Of the approximately 1.4 billion cubic kilometres of our planet's water supplies fresh water makes up less than three per cent. Most of this is tied up in glaciers, ice caps and snow fields, particularly in Antarctica. Only a tiny fraction of the Earth's fresh water reservoirs is easily accessible for human use. Lakes, wetlands and rivers, however, do not comprise the remaining major fresh water compartments. The continents of our planet are blessed with more than thirty times as much ground water as surface water.
Public opinion, however, is only too often preoccupied with the more obvious 'visible' surface water sources when it comes to water pollution, counter measures and restoration. This is at least partly due to their recreational value. Over the past few decades, the media in Germany, for example, have focussed especially on the water quality of German lakes and rivers which in some instances has indeed improved substantially. At the same time, the constant deterioration of the quality of ground water as a result of acidification and rising nitrate levels has been neglected almost completely.
Until very recently ground water has been thought of as being a standard of water purity in itself. And to a certain extent this is indeed true. Ground water is precipitation that does not evaporate or run off into a river but percolates through the soil and permeable rocks until it is held back by an impermeable layer of rock or clay. This process, which is called infiltration, along with the constant rising and falling of the water table and the length of time which infiltrated water stays and moves in the ground, all this ensures--under normal conditions--a high degree of purification.
Many modern pollutants, however, are extremely stable and the fact that it takes up to hundreds and thousands of years for aquifers (that is the name for such water-bearing layers) to turn over their water content, has backfired. Once ground water has become contaminated it is extremely difficult, if not impossible, to purify it.
There is still another fresh water reservoir: the atmosphere. Although relatively small it has the most rapid turnover rate. Within the hydrological cycle the atmosphere provides the important mechanism of distributing fresh water and replenishing terrestrial reservoirs. Acid rain is the most common pollution phenomenon with regard to atmospheric water.
Pure water is relatively rare in nature. When it evaporates, it soon becomes 'polluted' with aerosols and gaseous impurities that are present in the atmosphere. Ground and surface water, furthermore, contain dissolved minerals and organic matter. Pollution, however, is more than the presence of mere impurities. Water pollution is defined as any physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired uses. There has always been a natural influx of pollutants into water. Even naturally caused contamination as in the case of poison springs, for instance, took place long before humans started to influence our planet's ecosystems.
Human activities, however, have always led to fresh water pollution. Pollution is simply a question of the degree of dilution. Any substance can become a pollutant threatening an ecosystem if its concentration is too high. The immense increase of human activities during and after the Industrial Revolution has had two major consequences with regard to the environment: first, the release of pollutants has increased tremendously, particularly from the 1950s onwards. Secondly, mankind has begun to release man-made industrial pollutants of a completely different nature, many of which are characterized by high toxicity and slow degradability.
And yet not all human activities result in a direct influx of pollutants into the water cycle. Sometimes they only catalyze or trigger off a natural pollution chain. …