Biological monitoring of heavy metal pollution

A simple, inexpensive technique is described for detailed monitoring of airborne metal pollution using Sphagnum moss suspended in fine nylon hair-nets from natural vegetation. The technique was employed to monitor pollution, month by month, at forty-seven sampling points over a large area around a Zn and Pb smelting complex at Avonmouth, near Bristol. Maps of the area were constructed by computer, depicting the levels and patterns of distribution of Zn, Pb, and Cd collected by the moss-bags. The results are related to wind data, localised climatic conditions and topography. The reliability and practical significance of this simple biological monitoring technique is discussed, with particular reference to the collection and retention of metals by natural vegetation. Comparison is made between moss-bags and other standard monitoring devices.