ICMGP - Conference Presentation

Abstract Information :

Artisanal and Small-Scale Mining (ASGM) in South America is the largest Hg contributor of mercury releases globally. The Madre de Dios region of the Peruvian Amazon is the largest ASGM region in South America with recent estimates of 181 t Hg /y released to the environment, and a total of 123,000 ha deforested through 2020. Satellite analysis of post-mining landscapes show that approximately 40% of these areas have been converted from forests to a network of water-filled mining pits which are evolving into functional wetlands rapidly colonized by biota. This study reports measurements of Hg levels in birds and bats in areas around mining ponds in MDD. We collected feathers from 121 bird species, and fur from 32 bat species captured within a 1 km transect from ASGM mining ponds compared with samples collected from oxbow lakes as controls. In birds, we found that Hg levels from mining ponds were significantly higher than in control sites, a trend consistent across all trophic levels. Highest THg levels were found in mining ponds in piscivores (31.03 ñ 25.25 æg/g) and insectivores (2.64 ñ 3.73 æg/g), including one of the highest THg levels (72.8 æg/g) reported in the literature for the Green Kingfisher (Chloroceryle americana). In bats, the highest levels were measured in insectivores (24.01 ñ 28.09 æg/g) and piscivores (10.72 ñ 3.84 æg/g) in mining ponds. These piscivore measurements were consistent with previous studies that found fish Hg in mining ponds were higher than in oxbows lakes. This finding suggests that mercury is being transfer from the aquatic compartment to the terrestrial compartment via fish and aquatic insects and macroinvertebrates is occurring in these vast novel anthropogenic wetlands. Additional studies are needed to better understand the impact of this Hg transfer on ecosystems and wildlife in the Amazon region.