Problems and Concerns caused by Human Influences on the Environment

Water Pollution

Industries produce waste products which find their way into river water. One of the most serious pollutants of river water is hot water. Hot water increases the temperature of river water when the two are mixed. The result of this mixing is warm water which does not contain as much dissolved oxygen as cold water. This means, that many organisms are unable to survive in the warm water because they cannot respire efficiently.

Chemical wastes from industry and agriculture also find their way into rivers. At one time, even sewage was pumped directly into rivers. Sewage is the name given to human waste, both faeces and urine. All of these pollutants destroy much of the plant and animal life in rivers. The rivers which are most affected by pollution are those which flow through big cities, such as the Seine, the Rhine and the Thames.

Fortunately, because many people protested about polluted river water and polluted beaches, governments and local councils have started to make an effort to clean up the rivers. Industries are no longer allowed to put all of their waste products into river water. Sewage is treated in special "sewage farms" to make it harmless before it joins the river. There is still much to do, but on many stretches of once polluted rivers we can see fishermen, a sure sign that life has returned to the river waters.

FACT 1	The EEC has made laws stating the maximum concentrations of certain chemicals which can be allowed in drinking water. For nitrates, this is 5Omg/dm3. One problem with nitrates is that 100kg/ha are used each year by farmers to help fertilize arable land. These nitrates drain away with the rain water. If the land is ploughed more nitrates are released into the water. Too much nitrate in the drinking water can cause stomach cancer and affect the health of newborn babies.
FACT 2	Aluminium is another pollutant. The EEC allows a maximum concentration of 200µ/dm3. At high levels in the body, aluminium can cause arthritis, diarrhea and nausea. The EEC has limited the amount of lead in drinking water to 100µ/dm3. Although the drinking water contains safe levels of lead when it leaves the reservoirs, it is passed through old lead pipes before it reaches many homes. There are 10 million homes in Great Britain which still have lead water pipes. If the water which is flowing through these pipes is soft water, (soft water is slightly acidic), some of the lead in the pipes dissolves in the water. Too much lead in the body causes high blood pressure and heart disease. Lead also affects the brain.
FACT 3	Many people prefer to drink bottled water. There are some bottled waters, however, which have a greater concentration of certain chemicals, such as nitrates, than the EEC allows in drinking water. Also, when drinking water and bottled water were both tested for the presence of bacteria, the, bottled water was found to contain far more bacteria than the sample of tap water.

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© Paul Billiet, Shirley Burchill, Alan Damon and Deborah James 2009