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What are the Main Causes of Water Pollution?There are many causes of water pollution, some of them natural, some man-made and some natural but exacerbated by human activity. Here are some basic facts about water pollution from industry, agriculture and domestic sources.
Although industry and agricultural factors are huge, our domestic waste products have a considerable and increasing effect upon water pollution. Water companies are having to be more and more pro-active to deal with the deluge of bathroom and kitchen chemicals we use on a daily basis! This page focuses mainly on the industrial and agricultural causes of water pollution. Read on to learn more. Click here to read about what we can do to prevent domestic water pollution. Here is some reading about water pollution and some of the solutions
Picture above: Willows with their roots in water at the margins of a reservoir. Many rural bodies of water can be affected by water pollution, especially from agricultural run-off Natural organic wastes and soil can be one of the biggest causes of water pollution in some areas. Sediments build up over time in rivers and lakes as rain water washes soil, silt and organic debris< from the land. This process may lead to local problems for fish and other water-based living creatures. This natural process is made far worse when humans add an extra burden of wash-off from activities such as logging, construction and agriculture. The main causes of water pollution: Industrial discharges cause many, many water pollution incidents. Some stretches of river in the UK used to have no fish at all because the water was so polluted from factories routinely disharging effluent into them. Thanks to tighter controls most are now much cleaner; even the Thames now has fish once again. But this pattern of industrial pollution is being repeated in many countries. Some rivers in the east of Europe are now very heavily polluted. The Yellow River in China is now one of the most polluted waterways in the world; stretches of the river are now so toxic that animals drinking the water may die and many nearby communities are blighted by high levels of cancers. Industrial causes of water pollution are becoming more closely monitored and controlled in many countries.
The main causes of water pollution: Groundwater in underground aquifers (underground water sources) can also become polluted. This can happen even from household use of weed killers. A study in 1996 of groundwater wells in Iowa, USA, found that over half of them were polluted by chemicals from weed killers.
The main causes of water pollution:
Farmers' use of chemical fertilisers can also affect surface waters such as lakes and rivers and eventually end up in groundwaters too. Agricultural run-off often causes algae in the water to "bloom" or reproduce at an artificially fast rate, until the water is choked with organisms, which then tend to suffocate and die as there is not enough oxygen in the water to support them. When this happens, local fish stocks are affected too. Fish and other water organisms often find it hard to survive in the polluted waters.
By the lake near where I live there are notices put up every year warning people of the dangers of toxic blue-green algae (see picture below). These are an example of algal blooms. They happen because of the routine use of chemical fertilisers on the nearby wheat crops. 
The problem is especially bad where years of poor farming practice has led to dusty soils without enough structure to hold nutrients in place until they can be used by plants. If organic matter has been regularly returned to the soil a complex, rich soil structure is maintained and run-off is less likely to happen. Some of these problems can arise with organic fertilisers too, though they should be easier to avoid. Problems can occur as a consequence of poor farming practices, where organic manure is stored too close to water sources. Organic fertilisers (properly composted,) are less prone to causing agricultural run-off once they have been applied to the land because they help build soil structure. They are also generally less quickly dissolved by rainfall than many commercial fertilisers.
For more on organic growing methods please see Organic Gardening If there are too many nitrates (from fertilisers) in the drinking water supply this can lead to Blue Baby Syndrome a potentially fatal disease affecting newborn babies. Pesticides are one of the more important causes of water pollution.
Fungicides are used frequently on crops such as wheat to prevent fungi such as ergot. (Ergot is a real menace: it can cause a kind of mania.) Pesticides are often routinely used to prevent damage by airborne insects. A study by the National Geological Society (US) showed that 90% of the water sources tested were contaminated by pesticides from agriculture and other industries. Pesticide pollution is a growing concern world-wide. There are other ways in which farming affects ground and surface waters. Animals which are kept indoors or in small pens create manure which has to be disposed of carefully. If this is not done properly there may be contamination by run-off seeping into water supplies. The waste materials may carry harmful bacteria and will almost certainly have a polluting effect, bringing too many concentrated nutrients into local streams or ponds. This causes them to lose oxygen, ultimately stifling the organisms which would normally live there. Many people in the world still do not have access to clean, safe water. Sign this petion to help change that: Water Treaty
Other environmental pollutants such as petrochemicals and soot from industry or domestic fires may find their way into water systems. Soot may simply blow into water, carried on the wind. Petrochemicals residues and debris from tyres are washed down storm drains besides roads. The water coming off the surface of roads can contain a hazardous cocktail of chemicals. This can be a very significant source of water pollution, so much so that fish have been known to die after unusually heavy rain washes such residues away suddenly into nearby rivers. Also, some motorists still dump used engine oil into a nearby drain when carrying out an oil change and this finds its way into the water supplies. Petrochemical waste is one of the main causes of water pollution in urban areas.
Sewage is another human product which often ends up as a major pollutant of water sources. While this is not routinely a problem in the developed world, in developing countries there is often a serious lack of proper facilities for disposing of human waste. The United Nations estimated in 2000 that just under half the population of the earth (44%) was living with unsatisfactory sewage disposal systems. So sewage can be one of the main causes of water pollution for some people. Sewage also becomes more of a problem when there is a crisis, for example when flood waters swamp drains. In the developed world sewage can also pose other problems. For example, the birth control pill is getting into water supplies through its presence in urine flushed down the toilet. It has been shown to affect fish, causing feminisation and reproductive problems.
So what can we do to reduce some of these causes of water pollution? Water pollution is an issue which needs good co-ordination between government bodies and other public authorities to solve. But there are a few things we can do at home. Here are a few suggestions for ways to prevent water pollution from domestic sources.
There is not much you can do (in the short term) to stop the local farmer from using chemical fertilisers on his or her land and all the other industrial causes of water pollution are largely outside of our control. These problems are clearly political in scope. In order to effect change political lobbying and action are needed. This web site is non-political but there are plenty of organisations which are campaigning for more effective controls on polluters. Please consult the links page for pointers. However, you can take steps to ensure your own water supply is pure and fit to drink! Here's a website which has lots of good information on home water treatment methods and options For more on the importance of obtaining pure water please see this page
From The Causes of Water Pollution back to Green Earth
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Devra Davis looks at the consequences of unregulated industries and the blighting of people's lives and health by pollution. She is an epidemiologist who takes a scalpel to some of the political aspects of the issues, exposing how industrialists have deceived politicians, public and scientists alike. There is a first hand account of the pollution of her home town Donora by the coal, steel and zinc industries. A testament to all those who have pushed for better regulation and continue to do so.
The inspiring story of Chad Pregracke who set out to clean up the Mississippi - one of the largest rivers in the world. Not content with just that, he has gone on to found a movement to clean up all of America's rivers, involve and educate thousands of people and plant thousands of trees.
Marq De Villiers writes about the looming water crisis. Water is probably the earth's most precious and undervalued resource. This book is both an enjoyable travelogue and a disquieting appraisal of the scope of the world water shortage.
The amazing nature of water explained and explored for children with enquiring minds. Walter Wick presents fascinating insights to delight and intrigue - through photographs and the text. Around 9 - 12 year olds.
