The U.S. Celebrates Earth Day     The United States is celebrating an anniversary, too. Saturday is Earth Day, marking 30 years since the movement led to much needed reforms. Since 1970, the U.S. has initiated laws to protect the air, land, water, and endangered species. Perhaps, not the least of which is mankind. And now, an area of concern is the ozone shield that protects the earth's atmosphere. Washington is using electric power generated by biodegradable fuels during its Earth Day celebration.