Question

1. which of the following is most likely to cause conflict between two countries that share a river?

a. the upstream country drills a large number of new water wells.
b. the upstream country builds a series of new dams.
c. the downstream country uses an increasing amount of water for irrigation.
d. new industries dump pollutants into the river near the delta where the river empties into the ocean.

1. some communities have banned detergents containing high levels of phosphates because

a. phosphates cause chemical reactions that raise the temperature of river and lake water, disrupting ecosystems.
b. phosphates are not efficient cleansers.
c. excessive phosphates in lakes may begin a process that causes fish to suffocate and die.
d. phosphates kill algae and disrupt normal food webs in lakes

Explanation:

• For question 18: All the options (a, b, c) are known consequences of plastic trash in the ocean. Turtles do mistake plastic bags for jellyfish, sea - birds can be strangled by six - pack rings, and sea mammals can get entangled in fishing lines. So, option d is correct.
• For question 19: When an upstream country builds dams, it can control the water flow downstream. This can lead to water shortages in the downstream country, which is a major cause of conflict. Drilling water wells (a) is more of a local water - use issue. The downstream country using water for irrigation (c) is its own water use. Pollutants near the delta (d) is more of a pollution issue rather than a conflict - causing water - quantity issue.
• For question 20: Phosphates are nutrients. Excessive phosphates in water (eutrophication) can cause algal blooms. When the algae die and decompose, the decomposition process consumes oxygen, which can lead to fish suffocating and dying. Phosphates do not raise water temperature (a), they are efficient cleansers (b is wrong), and they do not kill algae but rather can cause excessive growth (d is wrong).

Answer:

1. d. all of the above
2. b. The "upstream" country builds a series of new dams.
3. c. excessive phosphates in lakes may begin a process that causes fish to suffocate and die