MERCURY LEVELS IN ALTO-PANTANAL - A SCREENING STUDY

Mercury (Hg) levels in soil, sediment, fish and bird feathers from nin e sites in the Alto Paraguay River Basin were determined with a hydrid e-generator coupled to an AAS. Large quantities of Hg, used in goldmin ing, are dispersed directly into the air and the rivers running into P antanal. The Pantanal ecosystem is of importance not only to the peopl e who live, fish, and raise cattle here, but also to citizens in faraw ay cities, who eat fish from the region or benefit from the economic s urplus generated by foreign tourists to Pantanal. Local, commercially important, catfish (Pseudo-platystoma coruscans) had a Hg content abov e the limit for human consumption (0.5 ppm w.w.), and significantly ab ove the natural background level. Mercury content in bird feathers als o indicated biomagnification. No statistically significant accumulatio n of Hg was found in soil and sediment samples. Evidently, Hg originat ing in the amalgamation process has a higher bioavailability than Hg n aturally present in soil minerals. Techniques for recycling the Hg use d in gold mining have not succeeded in decreasing the dispersion of Hg . Restrictions on the international trade of Hg would probably reduce Hg pollution significantly.