Elevated mercury exposure in bird communities inhabiting Artisanal and Small-Scale Gold Mining landscapes of the southeastern Peruvian Amazon

Abstract

Artisanal and Small-Scale Gold Mining (ASGM) represents a signi cant source of anthropogenic mercury release into ecosystems, with potentially severe implications for avian biodiversity. In the Madre de Dios department of the Southern Peruvian Amazon, ASGM activities have created landscapes marred by deforestation and post-mining water bodies (mining ponds) with notable methylation potential. While data on Hg contamination in terrestrial wildlife remains limited, this study measures Hg exposure in bird communities, using feathers as bioindicators. Total Hg (THg) levels in feathers from birds near water bodies, including mining ponds and oxbow lakes, were analyzed. Our results showed signi cantly higher Hg concentrations in birds from ASGM sites (3.14 ± 7.97 µg/g, n = 312) compared to control sites (0.47 ± 0.42 µg/g, n = 52). Factors such as trophic guilds, ASGM presence, and water body area signi cantly in uenced feather Hg concentrations. Notably, one measurement (72.7 µg/g) exceeded known concentrations that affect reproductive success in birds and is among the highest ever reported in South America. This research quanti es Hg exposure in avian communities in Amazonian regions affected by ASGM, highlighting potential risks to regional bird populations.

ASGM Mercury Discharges in Tropical Basins: Assessment of the Criticality of Their Geographical Distribution

“…Despite this, there is still no correct regulation regarding environmental pollutants, and also where standards exist, they are not considered and/or applied [41]. Here, the focus has been placed on the largest hydrographic basin because of the effects Hg discharges from ASGM can have on biota living in the mining areas [16]. Hg can also be discharged directly into water, accumulating in river sediments, where it can be converted to MeHg and rapidly incorporated into the aquatic biota [42].…”

“…Indeed MeHg is highly toxic for humans [13,14], and the areas where ASGM is practiced further represent an ethical problem due to the great presence of pregnant women and children [15]. Further, "post mining water bodies" have great methylation potential, exposing the ecosystems to biodiversity losses [16].…”