Trace metal research in the Amazon: A four-decade bibliometric analysis of trends and emerging perspectives

• Forty years of Amazon trace metal research mapped with bibliometric analysis • Rapid increase in studies reflects escalating Amazon metal-related impacts • Thematic networks reveal evolving priorities across environmental matrices • Shift from Hg-focused studies to Pb and Cd risks and ecosystem recovery • Scalable framework linking geochemistry, ecology, and health research Background: Trace metal contamination is a persistent environmental challenge in the Amazon, where mining, land-use change and hydrological alterations intensify metal mobility and ecological risks. Despite growing scientific attention, no comprehensive synthesis has assessed how research on this topic has evolved over the last four decades. Purpose and methodology: This study analyzes trends, collaboration networks, and emerging research fronts in Amazonian trace metal studies from 1984 to 2023. A total of 511 articles indexed in Scopus were examined using a PRISMA filtering strategy. Temporal patterns were evaluated through Price’s Law, the Price Index, and a third-order polynomial growth model. VOSviewer was applied to map co-authorship structures and keyword co-occurrence clusters, highlighting thematic evolution and recent research priorities. Observations: Scientific production increased exponentially over the 40-year period, with a pronounced surge in the last decade. The Price Index (45.9%) indicates a dynamic and expanding research field. Three major collaborative clusters were identified, reflecting distinct lines of inquiry related to geochemistry in mining areas, mineralogical characterization, aquatic contamination, and ecotoxicology. Keyword analyses revealed a historical focus on mercury associated with gold mining that has progressively shifted toward multi-metal contamination, ecological risk assessment, and organism-level metabolic responses. Recent trends emphasize Pb and Cd research, revegetation and rehabilitation of mining landscapes, and integrated approaches linking environmental quality and ecosystem recovery. Conclusions: Amazonian trace metal research is transitioning toward multidisciplinary. Strengthening collaboration, harmonizing monitoring strategies, and integrating geochemical, ecological, and health approaches will be essential for advancing predictive and risk-informed environmental management in the region.