There are four main sources of river pollution. The first
source is agriculture. Farmers put fertilizers and pesticides on ___1___
crops so that their crops grow better. However, these
fertilizers and pesticides can be washed away by rain to end up
in rivers.
Apart from that, factories ___2___
water from rivers to power machinery or to cool down machinery.
Dirty water ___3___
chemicals is released into rivers. The water used by factories
for cooling is ___4___
than the river itself, and this is also a form of pollution.
Waste water from old tin, coal and lead mines is another
source of pollution. When the mines were in use, there were
pumps ___5___
the mines dry. Now, water drips through the old mine shafts and
fills tunnels. The water reaches the surface by way of springs
after coming into contact ___6___
rusty machinery.
Another great ___7___ of
pollution is people. People are sometimes careless and throw
rubbish directly into rivers. Many seem to treat rivers as a big
garbage dump. They do not realize that they are polluting their
own drinking water. |