Every living thing depends on water for life. Over two thirds of the planet Earth is covered by sea water and there are also numerous freshwater habitats. Yet essential though all water is, humans continue to pollute it at an alarming rate. Here's how...
Freshwater - rivers, streams, lakes and ponds
One of the biggest threats to water purity comes from chemicals. Fields are often sprayed with pesticides and herbicides. Rain washes them off the crops into nearby streams and rivers and the bacteria which normally break down the remains of dead animals and plants in the water cannot deal with the chemicals. Animals and plants are immediately poisoned and the balance of life is seriously affected.
Artificial fertilisers containing nitrates and phosphates, "slurry" (liquid animal manure), combined with phosphates from domestic effluent such as washing powders, can also be washed into water ways. These do not poison water life directly but cause the water plants, particularly algae, to grow rapidly. The algae uses up so much oxygen that there is none left for the plants and animals. The growth also blocks out sunlight, leading to the death of underwater life. Eventually the algae itself dies, leaving a stinking, decaying mass. This problem of excess fertilisers in water is called eutrophication.
Factories, often built beside rivers so that water can be used, may discharge poisonous chemical waste into the water so killing the river-life.
Sewage works clean waste water from our homes and then discharge it back into the rivers. Bacteria in the filter beds digest the organic waste matter but if the water contains chemicals, such as bleach, the bacteria die and polluted water is often returned to the rivers. The water is also so depleted of oxygen that the animals cannot live in it.
Power Stations use water and when returned to the river it is often so warm that animals may die and plants grow so quickly that they may die too. Acid Rain, as described under "air pollution" is often concentrated strongly enough in rivers to kill fish.
Finally, the dumping of rubbish causes enormous damage. Streams, ponds and rivers are regularly used for dumping anything from old cans to cars. Landfill sites are the burial grounds for dangerous chemicals and metals such as cadmium and mercury from batteries. They can seep through the soil and find their way into rivers.
The pollution described above can easily end up in sea water simply by being transported there by rivers. River estuaries and coastal waters are particularly affected. In addition, a lot of waste is deliberately dumped in the open sea. The most serious problem is radioactive waste which began to be disposed of after the second World War. Some of the containers have leaked and we are still not sure of the long-term impact on marine life.
Enormous quantities of sewage, often untreated, containing dangerous chemicals and bacteria, are discharged into the oceans. Spills from oil tankers are another major hazard to marine life.
PCBs (polychlorinated biphenyls) have numerous uses in industry and can be scattered in smoke or washed into waterways. They almost all end up in the sea and can become extremely concentrated as they travel along marine food chains. Back in 1969 in the Irish Sea, thousands of guillemots were killed as a result of PCB poisoning. Since then it has been discovered that other animals such as polar bears, seals and whales have accumulated high concentrations of PCBs in their bodies. It is believed that their reproduction could be affected, thus leading to their eventual extinction.
Oceans are connected to each other and because of this, the pollutants are carried in currents and tides and spread around the world. The pollutants enter the food chains in the oceans working their way up from the phytoplankton to the higher animals. Some of the pollutants may end up on our dinner plates!
It is obvious from the information that you have just read that we are producing far too much waste! The earth simply can't cope with all this pollution. We are at least now becoming aware of the problems of pollution - But is anything Being done to control it?
Scientists have discovered that under the microscope water samples taken from beaches show tiny bits of plastic, also known as microplastic. This microplastic shouldn't be here so where has it come from?
Researchers took 18 samples from beaches around the globe including the UK, US, India and Singapore. They found that all the samples contained this tiny plastic pollutant which could be causing harm to our marine environments, and also making its way into the food chain.
Plastics such as polyester, acrylic and nylon were among the major finds across the samples, do you recognise these names? Take a look at a clothes label and you will very often find that it is made out of one of these synthetic fibres. Man-made fibres account for 68% of fibres used worldwide but how do these plastics end up on our beaches? Through our washing machines.
The researchers discovered that just one garment released up to 1,900 microplastic particles per wash! On a washing cycle when the machine is finished all the dirty water flows into sewers before being treated and flushed out to sea or in rivers. The microparticles aren't filtered out by water treatment, so make it out to sea.
These particles are swallowed by animals and can become lodged in their cells. In 2004 scientists tested plankton samples right back to the 1960s and found that the levels of microplastics had increased significantly over time. The nature of plastic is that it stays around for a long time, taking hundreds if not thousands of years to break down, and it is thought that microscopic plastics will never entirely disappear or decompose.
It is not yet known what the long term effects of this kind of pollution may be. But what we do know is that this plastic pollution will only increase as the production of synthetic fibres rises. In 2010, worldwide production of man-made fibres amounted to a whopping 53 million tonnes.
A UK ban on the sale of products containing micro beads came into force in 2018 as part of a plan to prevent these harmful pieces of plastic entering the marine environment.Read More: What can be Done About Pollution?