48. Hazardous waste is:  

68. What is the major cause of ocean acidification?  

56. What happens when the water table drops below sea level in aquifers near the ocean?  

69. What allows CO2 to mix quickly into the top 100 feet of water from the atmosphere?  

71. What effect do acidic ocean waters have on shells made of calcium carbonate?  

46. Americans produce _____ amount of solid waste produced by most less-developed countries.  

42. Tiny bits of plastic gather in specific areas of the world’s oceans where strong currents circle around areas with very weak, or even no, currents. These regions are called:  

67. What was the dramatic event that helped spur passage of the 1972 Clean Water Act?  

34. The ozone layer is located in the:  

66. The Mississippi River watershed includes land area from: