Vegetation-associated mercury patterns and biogeochemical signals in a tropical urban mining region

Schneider, Jerusa, Brito, Sheyla dos Santos, Kunifoshita, André Massanobu Ueno, Andrade, Ricardo Lopes Tortorela de, Fostier, Anne-Hélène, Lambert-Smith, James ORCID: https://orcid.org/0000-0003-3522-1009 and Mesquita, Maria José Maluf de 2026. Vegetation-associated mercury patterns and biogeochemical signals in a tropical urban mining region. ACS Omega 10.1021/acsomega.6c07837

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Abstract

To evaluate vegetation-associated mercury (Hg) loading in tropical regions affected by artisanal and small-scale gold mining (ASGM), we quantified total mercury (HgT) in canopy leaves and leaf litter of Licania tomentosa across an ASGM-impacted urban center, Peixoto de Azevedo (PEI), and two lower-exposure reference sites: Nova Santa Helena (ASH) and a native forest fragment (ANM). Canopy leaves reached up to 543 μg kg–1 near gold-buying shops, with probabilistic modeling identifying a high-concentration subpopulation extending to 607 μg kg–1. Leaf litter consistently exhibited higher HgT than paired canopy leaves (RatioC = 1.39–4.70; mean = 3.15), indicating relative enrichment during senescence. Spatial interpolation suggested sharply localized vegetation-associated Hg hotspots within ∼300 m of gold-trading units, superimposed on a heterogeneous urban baseline. The regional baseline was defined using ASH, where HgT concentrations ranged from 6.82 to 35.31 μg kg–1 after excluding a single transport-related outlier. These results demonstrate that gold-trading corridors are plausible localized contributors to elevated HgT in urban vegetation and may produce Hg-enriched biomass that can enter municipal waste streams. This framework provides a high-resolution, low-cost approach for Hg surveillance in tropical ASGM regions and offers chemically grounded insight into vegetation-associated Hg patterns and biogeochemical partitioning in urban environments.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Earth and Environmental Sciences
Publisher:	American Chemical Society
ISSN:	2470-1343
Date of First Compliant Deposit:	22 October 2026
Date of Acceptance:	8 October 2026
Last Modified:	22 Oct 2026 10:45
URI:	https://orca.cardiff.ac.uk/id/eprint/190369

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