Environmental Science Chapter 12

What percentage of Earth's water is fresh and available for drinking?

2.5%. Very little of all Earth's water is freshwater and available to the living organisms of Earth for drinking.

What percentage of Earth's surface is ocean?

71%. This area varies over geologic time.

Which is the correct term to describe fish and other ocean organisms that are caught accidentally along with the targeted fish?

Bycatch. Bycatch is the accidental capture of nontarget species.

If the captain of a fishing fleet wanted to catch fish over a vast expanse of ocean, which of the following would be an effective method to do so?

Driftnets. These nets are held vertically near the surface of the ocean using floats at the top and weights at the bottom.

Which of the following is the name for water that has been used by humans and then treated for release back into the environment?

Effluent. Treated water (called effluent) is often piped into rivers or the ocean after primary and secondary treatment.

Which of the following is a systematic shift in atmospheric pressure, sea surface temperature, and ocean circulation patterns in the tropical Pacific Ocean that alters weather patterns on a worldwide scale?

El Niño-Southern Oscillation (ENSO). These cycles are periodic but irregular, occurring every 2-8 years.

Which of the following statements about China's Three Gorges Dam is true?

It will generate enough power to replace dozens of coal and nuclear plants. One of the main reasons that the dam was built is to provide hydroelectric power.

Which of the following statements about ocean water is true?

Oceans have a high heat capacity and change temperature slowly. High heat capacity enables ocean water to absorb a tremendous amount of heat from the air. By absorbing heat and releasing it to the atmosphere, the oceans help regulate Earth's climate.

What is the spatial relationship between the distributions of water and people?

Populations and water resources too often have an inverse relationship (lots of people where there is little water). Canada and the Amazon basin have abundant freshwater but very low population densities, while Pakistan, Iran, and Egypt have high population densities and little freshwater.

Dams create a __________ from which we can get water for human use.

Reservoir. Reservoirs are artificial lakes that store water for human use.

Why are benthic organisms NOT a bycatch of longline fishing?

The long lines are dragged behind the boat on floats and do not generally scrape the ocean floor. Ocean bottom, or benthic, organisms are generally not harmed by this method of fishing.

What happens as you descend from the ocean surface to the deeper layers of the ocean?

The temperature decreases. The upper layer is heated by the sun, but in all oceans the temperature drops to just above freezing below 1,000 meters.

Which term describes a regular periodic change to the ocean's height due to the gravitational influence of the moon and the sun?

Tides. Tidal cycles occur on, roughly, a monthly basis.

What is the direct cause of death for aquatic animals during eutrophication?

a loss of dissolved oxygen in the water. Eutrophication occurs when excess nutrients cause a bloom of algal growth that then is decayed by bacteria, which use up all of the oxygen.

What is the most cost-effective solution for groundwater depletion and land-level subsidence?

allowing no more water to be withdrawn from an aquifer than is naturally recharged. This would be a water conservation measure that would solve both problems with minimal expense.

What is a marine protected area?

any portion of the ocean that is protected from some human activities but may be open to others, such as the laying of cables and some fishing. The area is a marine protected area, rather than an area of preservation.

A(n) __________ is a water-bearing unit that is confined by less permeable or impermeable rock or soil.

artesian aquifer. A confined aquifer is also called an artesian aquifer. The pressure from the layers of rock or clay above forces the water out of a well dug down to this layer, making an artesian well. (In an unconfined aquifer, the water must be actively pumped out.)

Which of the following fishing methods involves dragging weighted nets across the ocean floor in an attempt to catch groundfish?

bottom-trawling. Bottom-trawling involves dragging weighted nets across the ocean floor.

Which of the following would make flooding worse?

building dikes and levees to hold water in channels. These force water to increase in volume, building up enormous amounts of energy and leading to catastrophic overflow events.

What technology is used to extract freshwater from ocean water?

desalinization. This technique is expensive and tends to be utilized only in wealthy, oil-rich nations within desert biomes.

What type of coastal feature experiences fluctuations in salinity with daily and seasonal variations?

estuaries. Estuaries are where rivers flow into the ocean; this is where ocean water mixes with freshwater.

Which of the following is a non-consumptive use of water as a resource?

hydroelectric power. Water flows through turbines at hydroelectric dams and is passed on downstream intact.

According to a comprehensive review of data from marine reserves in 2001, how can marine reserves benefit ecosystems?

increased biomass of organisms. This is one benefit that marine reserves provide. Others are average size of organisms, increased species diversity, and increased size of organisms.

Ocean water is 96.5% water by mass. Most of the remainder consists of

ions from dissolved salts. These run off from the land and are concentrated through the evaporation of water.

The region of a lake where plants are able to attach to the bottom and still reach above the surface is known as the

littoral zone. This region contains nutrient-rich edges of a water body, with shallow water and lots of invertebrates that are prey for fish, birds, turtles, and amphibians.

Why is primary production and animal life concentrated at the surface in pelagic regions of the open-ocean?

nutrient upwellings. These supply productivity to the surface with nutrients from beneath the pelagic zone.

What caused the Aral Sea, the fourth largest lake on Earth, to lose four-fifths of its volume in 40 years?

overconsumption by cotton farmers. Water for irrigating cotton, a crop with very high water demands, was the major cause of the Aral Sea disappearing.

What is one of the chemical properties of water that scientists and technicians use to assess water quality?

pH. pH measures the acidity or basicity of water.

Which of the following types of pollution is most responsible for large numbers of deaths worldwide because of unsafe drinking water?

pathogen pollution. Biological organisms that exist in the water of many developing countries can make people sick, and the diseases that come from them are a leading cause of death worldwide.

Which of the following pollutants does not occur naturally in groundwater?

petroleum products. Petroleum from natural seeps can occur in groundwater, but petroleum products are created by human activity.

What type of farming has led to the destruction of mangroves?

shrimp. Shrimp farming converts mangrove forests to fish farms.

What is the pollution that occurs when human activities raises water temperatures called?

thermal pollution. When we withdraw water from a river, use it to cool an industrial facility, and return the heated water to the river, or when we remove streamside vegetation, water temperature increases.

Which of the following wetland environments only occurs for a short period of time each year?

vernal pools. Vernal pools are formed from snowmelt or spring rains and typically dry out by the end of the summer.

What is an area of land in which all freshwater converges into the largest stream, ultimately draining into the largest body of water?

watershed. The area of land drained by a river and all its tributaries is that river's watershed, which is also called a drainage basin.

In which of the following units is pore space partially saturated with water?

zone of aeration. Water is under tension due to the presence of air in the zone of aeration, or vadose zone, near Earth's surface.