Possible answers might include the following points: ■ Turbidity is
the result of suspended particulate matter in the water, which causes
the water to become “cloudy.” These particulates can consist of
phytoplankton, sediments, algae, air pollutants, and/or particulates
originating from urban runoff. Therefore, cultural eutrophication and
soil erosion can both lead to increased levels of turbidity in the water
bodies.
■ Agriculture, deforestation, road-building, and urban sprawl are
human activities that change the amount of vegetation within a
watershed (an area of land that drains to a particular body of water).
Deforestation has an impact on the quality of water flowing
through the watershed and alters the discharge, chemical, and
physical properties of water.
■ With an increased rate of deforestation, the turbidity of water bodies
around the forested areas can increase as the main purpose of tree
roots is to anchor the soil particles together. When the trees are
removed, the soil particles become loose and soil erosion can
increase because of increased surface runoff. As a result, these soil
particles are washed into the surrounding water bodies.
■ Turbidity affects water quality by increasing soil particulates in the
water. As a consequence, light does not penetrate through the water
and aquatic plants at the bottom of the rivers cannot survive as they
are unable to photosynthesize. This affects the entire food web.
■ Fine particulate material in the water, such as heavy metal ions
released from soil erosion, can bind to gill structures of fishes and
interfere with their intake of calcium ions. This can lead to
bioaccumulation and biomagnification of the heavy metals when
passed on to organisms of higher trophic levels as they feed on the
aquatic plants and the fish.
■ Turbidity can impact, interfere with, and harm the immune system
of some fish, increasing the rate of disease and jeopardizing the
overall health of the ecosystem.(c) (i) 2 points possible. 1 point maximum for the correct definition of
“deforestation” and 1 point maximum for one effect of deforestation
on the hydrologic cycle in the tropical rainforest.
Describe deforestation and its effects on the hydrologic cycle in the
tropical rainforest.