Mercury fluxes in a natural forested Amazonian catchment Serra do Navio, Amap´a State, Brazil/

Mercury Hg total. fluxes were calculated for rainwater, throughfall and stream water in a small catchment located in the northeastern region of the Brazilian Amazon Serra do Navio, Amap´a State., whose upper part is covered by a natural rainforest and lower part was altered due to deforestation and activities related to manganese mining. The catchment area is 200 km from the nearest gold mining garimpo.. Minimum and maximum Hg concentrations were measured monthly from October 1996 to September 1997 and were 3.5]23.4 ng ly1 for rainwater, 16.5]82.7 ng ly1 for throughfall March]August 1997. and 1.2]6.1 and 4.2]18.8 ng ly1 for stream water, in natural and disturbed areas, respectively. In the natural area, the inputs were 18.2 mg my2 yeary1 in rainwater and 72 mg my2 yeary1 in throughfall. This enrichment was attributed to dry deposition. The stream output of 2.9 mg my2 yeary1 indicates that Hg is being recycled within the forest as other chemical species or is being retained by the soil system, as confirmed by the cumulative Hg burden in the 0]10 cm surface layer, which was 36 480 mg my2. When the disturbed area of the catchment was included, the stream output was 9.3 mg my2, clearly indicating the impact of the deforestation of the lower part of the basin on the release of mercury. The Hg burden in the disturbed area was 7560 mg my2 for the 0]10 cm surface layer.