From Rivers to Oceans

Which factor has the greatest effect on a community’s stores of fresh water?

• the location of the nearest ocean

• the average annual rainfall

• the abundance of macroinvertebrates

• the average winter temperature

The model shows how water flows in two drainage basins. Identify the labeled features in the drainage basin on the left.

• 1—watershed; 2—river; 3—tributary

• 1—watershed; 2—tributaries; 3—river

• 1—divide; 2—tributaries; 3—river

• 1—divide; 2—river; 3—tributary

A small city gets its drinking water from the river running through its center. This river is fed by rivers that flow down the mountains nearby. How would excessive rainfall in the mountains most likely affect the turbidity of this local water source?

• Heavy rainfall would decrease the turbidity of the river downstream.

• Heavy rainfall would increase the turbidity of the river downstream.

• Heavy rainfall would increase the turbidity of only rivers upstream.

• Heavy rainfall would decrease the turbidity of only rivers upstream.

Which factors can have the greatest effect on the health of a river system?

• type of soil and salinity

• nitrate levels and turbidity

• human consumption and pH

• natural disasters and tidal changes

Which best determines the health of a lake used as a source of freshwater?

• its depth and width

• its temperature and pH

• its location and depth

• its temperature and depth

Turbidity measurements were taken at different distances from the shore of a lake.

Which best explains why the turbidity increases as water samples are taken closer to the shore?

• Shoreline erosion causes sediment to wash into the lake.

• Sediment is carried from the middle of the lake to the shore by wind.

• Swimmers stir up sediment by splashing in the water near the shore.

• Fish stir up sediment while feeding on plants that grow close to the shore.

Which will occur if humans continue to overload water systems with excess nutrients?

• chemosynthesis

• eutrophication

• nitrification

• photosynthesis

Which does an increase in eutrophication indicate to scientists studying a body of water?

• an increase in fertilizer runoff

• a decrease in pollutants from farm runoff

• an increase in the health of the body of water

• an increase in oxygen levels in the body of water

Which aspect of fertilizer pollution would have the greatest negative impact on an aquatic ecosystem?

• Nitrates poison the water that fish breathe through their gills.

• Microorganisms in the water absorb all the oxygen, suffocating animals.

• Aquatic animals increase, adding producers to the food chain and feeding fish.

• Algal blooms deplete the oxygen and block the sunlight from penetrating a body of water.

Which would most affect the health of fish in a local pond?

• The daily release of hot water into the pond from a local factory.

• A storm temporarily stirring up water and sediments in the pond.

• The occasional erosion of sediments into the pond from a nearby field.

• A slight increase in the number of people who fish in the pond for food.