Systematic Review and Spatiotemporal Assessment of Mercury Concentration in Fish from the Tapajós River Basin: Implications for Environmental and Human Health.

This study reviews the literature on mercury (Hg) pollution in the Tapajós River basin from 1992 to 2022, focusing on the bioaccumulation in fish and the associated health risks to humans via ingesting contaminated species. Variability in Hg bioaccumulation was analyzed from both spatial (sub-basins) and ecological (trophic levels) perspectives. Mercury concentrations in fish muscle tissue and spatial differences in Hg levels were analyzed using nonparametric Kruskal-Wallis ANOVA and mapped with Inverse Distance Weighting. Additionally, a risk assessment of mercury contamination was conducted using the Target Hazard Quotient (THQ) and Maximum Safe Consuming Quantity (MSCQ) indices. Results indicate that Hg contamination is pervasive across the basin, with piscivorous fish showing the highest Hg levels, particularly in the middle Tapajós, upper Tapajs óand Teles Pires sub-basins, identified as contamination hotspots. Piscivorous species exhibited high Target Hazard Quotients (THQ), suggesting health risks for local consumers. The MSCQ values indicated that 75% of the fish species analyzed should be consumed in quantities lower than the current consumption daily average to avoid health risks.