Sulfur is a key nutrient for all living creatures. It is an essential nutrient that we often overlook. For many years sulfur was free. It was being emitted by coal burning power plants, diesel fuel vehicles and other sources. This sulfur was caught in the clouds and returned to the earth by rainfall. However, this rain was acidic due to the sulfur dioxide and Nitric acid. The acid rain was causing negative side effects in lakes and water ways killing fish and reptiles in lakes and ponds. Also killing some types of trees and other vegetation. With acid rain causing environmental problems the EPA made laws and set restriction on sulfur and nitric acid emissions reducing the sulfur levels.