Zinc is Natural
Zinc is constantly transported around our environment by nature through a process called natural cycling. Rain, snow, ice, solar heat and wind erode zinc-containing rocks and soil. Wind and water carry minute amounts of zinc to lakes, rivers and the sea, where it collects as sediment or is transported further. Natural phenomena such as volcanic eruptions, forest fires, dust storms and sea spray all contribute to the continuous cycling of zinc through nature.
During the course of evolution, all living organisms have adapted to the zinc in their environment and have used it for specific metabolic processes.
The amount of zinc present in the natural environment varies from place to place and from season to season. For example, the amount of zinc in the earth’s crust ranges between 10 and 300 milligrams per kilogram, and zinc in rivers varies from less than 10 micrograms per liter to over 200 micrograms. Even falling leaves in autumn lead to a seasonal increase in zinc levels in soil and water.
The zinc industry has supported numerous studies in aquatic, terrestrial and atmospheric systems to further the understanding of the natural variations of zinc in the environment. Consideration of background zinc concentrations has assisted environmental risk assessment efforts by providing a context for biological acclimation and adaptation.
Zinc Emissions to the Environment
Sea salt and the movement of soil dust particles in the air are the principal sources of natural zinc emissions in the atmosphere. Forest fires and volcanoes also contribute in a minor way to zinc’s natural cycling. It is estimated that these natural emissions of zinc amount to 5.9 million metric tonnes each year.
By comparison, anthropogenic emissions of zinc to the atmosphere – those that result from man’s activities, such as metal production, waste disposal and fossil fuel combustion - are estimated at only 57,000 metric tonnes each year.
For more information, please visit http://www.zinc.org/sustainability.