Overpumping groundwater in coastal areas can cause ________ to move into aquifers, making the water undrinkable.
saltwater
Sinkholes can occur when ________.
excessive water use lowers a water table and weakens the substrate
Only about 2.5% of all the water on our planet is freshwater, however, ________.
most of this is in polar ice caps, glaciers, and underground aquifers and is not easily accessed for human use
You want to maintain a healthy pond at your school site. Last year another pond became eutrophic; to avoid that, you want to ________.
avoid increasing phosphorus runoff into the limnetic zone
We build dams to ________.
generate electricity, prevent flooding, and provide irrigation and drinking water
The primary effect of thermal pollution on aquatic ecosystems is ________.
depleting dissolved oxygen
In thermohaline circulation of global current systems, surface water is ________.
less salty, less dense, and warmer
Frog eggs are usually attached to vegetation or rocks near the surface of a pond. Tadpoles can use essentially all areas of a shallow pond, or the top few feet of a deeper pond or lake. Adult frogs can live on land or in the water. A frog's life would be
benthic zone
The exceptionally strong warming of the eastern Pacific is referred to as ________.
El Ni�o
Of the following, ________ best describes floodplains.
a region of land that is periodically flooded when a river overflows
The area that underlies the shallow water bordering continents is called the ________.
continental shelf
Freshwater wetlands provide important ecosystem services, including ________.
recharging aquifers
slowing runoff
filtering pollutants
reducing flooding
Of the following, ________ characterize(s) an oligotrophic lake or pond.
high oxygen concentrations
low nutrient levels
What happens as you descend from the ocean surface to the deeper layers of the ocean?
The temperature decreases.
Zooxanthellae are ________.
symbiotic algae that provide energy to many species of corals
Upwelling ________.
brings benthic nutrients to the ocean surface promoting high primary productivity
Ocean water is 96.5% water by mass. Most of the remainder consists of __________.
ions from dissolved salts
All of the following are examples of point sources of pollution except ________.
a large farm
Salt marshes are ________ ecosystems, while mangroves are ________.
temperate intertidal; found on subtropical and tropical shorelines
In which of the following units is pore space partially saturated with water?
zone of aeration
Pathogens and waterborne diseases enter drinking water supplies from ________.
poorly treated wastewater or from animal wastes from feed lots
Water bodies where rivers flow into the oceans, mixing fresh water with saltwater, are called ________.
estuaries
Of the following, ________ is one of the major pollutants of groundwater.
fertilizers from agricultural fields
Data indicate that the present rate of freshwater consumption in most developed countries is ________.
unsustainable
Recent research that analyzed the content of commercial bottled water indicates that ________.
bottled water is no safer or purer than most samples of tap water
The pair of mallard ducks in the figure eats floating plants such as duckweed, seeds of shoreline plants, and very small organisms at or near the surface. They would be most affected by any change to the ________.
littoral or limnetic zones