a) Finnish water environments are spoiled easily because:
the waste water treatment in Finland is not effective enough.
Finnish water environments are shallow and contain relatively little water.
the soil has been polluted.
boat traffic pollutes water environments.

b) Eutrophication is caused by
oxygen and nitrogen
chloride and carbon
calcium and mercury
nitrogen and phosphorous

c) An eutrophicated lake
contains a lot of nutrients.
becomes very clear.
is dominated by floating-leaf and aerial shoot plants.
is home to no birds.
contains a lot of invertebrates.
becomes murky.

d) The lack of oxygen is a problem that
often occurs during the winter.
is caused by acid rain.
causes the amount of perch to increase.

e) To prevent eutrophication, we must:
cut down on fishing.
leave a buffer zone between a lake and an agricultural field.
treat waste water efficiently.