Working Group on Terrestrial Mercury Cycling

Abstract

The behavior of Hg in the terrestrial environment has been discussed by several authors at recent international meetings. Many of these papers are presented in volumes edited by Lindqvist (1991), Watras and Huckabee (1994), and Huckabee et al. (1995). The Terrestrial Mercury Cycling group identified six important achievements as a result of this and other recent work which serve to highlight our state of knowledge on Hg in terrestrial systems. These include (1) the discovery of measurable concentrations of MeHg in terrestrial compartments and in waters draining terrestrial systems, (2) the recognition based on both new data and modelling that dry deposition is the dominant input process to forests, (3) micrometeorological and chamber data which indicate that Hg emission and reemission from forested systems may be significant, (4) measurements in forests which suggest that the Hg flux in throughfall plus litterfall can provide a simple and cost-effective estimate of total annual Hg deposition to forests, (5) the discovery of a significant downward trend in the concentration of Hg in air and rain in Europe between 1990 to 1995, and (6) the documentation of significant areas of Hg contamination due to industrial and mining activities in countries of the former eastern block.