Air pollution, 49(11), 52(146), 214(42), 239(89), 387(32), 465(47), 532(68)
Beach erosion, 518(41), 533(89)
Forest fire, 52(150)
Insecticide DDT, 385(66), 394(52)
Lake pollution, 106(58), 532(74)
Nuclear power plant discharge, 177(89)
Oil spill, 26(47), 70(), 83(71), 653(55, 56, 57, 58), 654(51, 52, 53, 54)
Organic pollution, 652(41, 42, 43, 44)
Ozone layer, 401(89)
Recycled cars, 49()
River flow, 48(), 52(144)
Stream pollution, 42(50)
Water supply testing, 651(17, 18, 19, 20)