Annual emissions of anthropogenic Hg to the atmosphere in different regions of the world during the last decade show an interesting dichotomy: the emissions in the developed countries increased at the rate of about 4.5–5.5% yr−1 up to 1989 and have since remained nearly constant, while in developing countries the emissions continue to rise steadily at the rate of 2.7–4.5% yr−1. On a global basis, however, the total anthropogenic emissions of Hg increased by about 4% yr−1 during the 1980s, peaked in 1989 at about 2290 t and are currently decreasing at the rate of about 1.3% yr−1.

A proper inventory of atmospheric emissions from natural sources is basic to our understanding of the atmospheric cycle of the trace metals (and metalloids), and is also needed for assessing the extent of regional and global pollution by toxic metals1. It is generally presumed that the principal natural sources of trace metals in the atmosphere are wind-borne soil particles, volcanoes, seasalt spray and wild forest fires2–6.

Calculated loading rates of trace metals into the three environmental compartments demonstrate that human activities now have major impacts on the global and regional cycles of most of the trace elements. There is significant contamination of freshwater resources and an accelerating accumulation of toxic metals in the human food chain.