Answer to Question 1
There are four problems with landfills: leachate generation and groundwater contamination, methane production, incomplete decomposition, and settling. Newer landfills are built with leachate collection systems, and groundwater monitoring wells are installed so that continuous monitoring of groundwater will occur. Methane collection systems are being installed as a standard part of the landfill. To improve the cost effectiveness of methane collection systems, decomposition rates are increased by adding moisture. Two additional benefits to speeding decomposition are that leachate production does not continue for the same length of time, and settling is more rapid. If decomposition rates are increased, more material can be buried in the same location because decomposed material occupies less space.
Answer to Question 2
There are seven key issues: (1) Water efficiency must be promoted as the primary strategy for meeting future water needs. (2) Water subsidies need to be reduced or eliminated. (3) Polluters must be charged according to their effluents. (4) Watershed management must be integrated into the pricing of water. (5) Water authorities must regulate dam operations so that river flow is maintained in a way that simulates natural flow regimes. The United States must respond to the global water crisis with adequate levels of international development aid. (6) The United States must take action to reduce the emissions of greenhouse gases that are bringing on global climate change. (7) Much more research and monitoring are needed to provide the basic data for making informed policy decisions.
The process of placing a stent in a blood vessel. (A) A catheter is used to place a collapsed stent
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