The Garbage (垃圾) Project started at the University of Arizona in 1973. Since then, the students and teachers in it have studied the modern garbage in different cities.
To study the garbage, the students had to travel to landfills (填埋场) , the places where cities bury (填埋) their garbage. While the students were studying the garbage they wore special clothes. Students were very careful when they opened bags of garbage.
One important thing the students have learned from studying the garbage is that the garbage in landfills disappears very slowly. That was surprising to both the students and many scientists who had thought that about 70 % of the garbage in landfills would disappear quickly. Even in cities where it rains a lot, the students found newspapers from 1948, 40-year-old hot dogs, and vegetables from 1970. And the students also found many more empty bottles of cola than they expected.
How to dispose of our garbage well depends on what kind of garbage it is: regular(普通的) garbage, dangerous materials, or recyclable materials, such as newspapers and glass bottles. Regular garbage goes to regular landfills. Dangerous materials are harmful to people's health and the environment. They shouldn't go into regular landfills.
Homes are full of dangerous waste. One kind of the dangerous waste in homes is batteries. When batteries are buried directly（直接地）in a landfill, they often break open. The poison inside them moves through rain water to the bottom of the landfill. Then it can pollute the natural water in the ground.
Another dangerous waste from homes is motor oil. When people pour old motor oil on the ground or throw it in the garbage, it pollutes the environment.
Our garbage problem is not new, but as the world's population continues to grow, it will become a bigger and bigger problem.
