Assessment of Atmospheric Mercury Deposition in the Vicinity of Artisanal and Small-Scale Gold Mines Using Glycine max as Bioindicators

Abstract

Artisanal and Small-scale Gold Mining (ASGM) is one of the main sources of global Hg emissions and is present over a wide territorial in the southern Amazonia. In this region, there is a rapid approximation between agricultural and livestock activities and the impact of this close proximity having little or no evaluation. Thus, we have determined the Hg concentration in soybean plants in an area with ASGMs activities. The concentration of Hg in plants was higher in the vicinity of the ASGMs, where the Hg leaf concentration was three times higher, suggesting a higher atmospheric metal deposition in this area. It is estimated that atmospheric Hg deposition in the vicinity of ASGMs of up to 6.94 g km−2 during the contact time between leaves and atmosphere. The translocation and bioaccumulation factors reinforce the effect of atmospheric Hg deposition, mainly, in the leaves. No impact was observed on the edible part of the plant due to the proximity of the ASGMs. It can be inferred that our results point to considerable rates of Hg emissions in the southern Amazon region and indicate the need to monitor these emissions so as to facilitate the taking of pollution mitigation actions. Soybean plants have a potential use as a bioindicator species of Hg contamination from ASGM, and the proposed method consists of an viable alternative, which can be used for the biomonitoring of long-term Hg emissions.